Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 03/20/07

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
200 PM PDT SUN MAR 18 2007 .SYNOPSIS... UPPER LEVEL LOW PRESSURE AND A COASTAL EDDY WILL MAINTAIN A DEEP MARINE LAYER. SKIES WILL BE MOSTLY CLOUDY NEAR THE COAST WITH AFTERNOON SUNSHINE IN THE VALLEYS. IN THE INTERIOR IT WILL BE FAIR AND COOLER. FOG AND PATCHY DRIZZLE IS POSSIBLE WEST OF THE MOUNTAINS IN THE NIGHTS AND MORNINGS. THE LOW PRESSURE WILL MOVE THROUGH THE REGION TUESDAY EVENING AND WEDNESDAY BRINGING SOME SHOWERS AND STRONG WINDS MAINLY TO THE MOUNTAINS AND DESERTS. DRIER NORTHERLY WINDS WILL ARRIVE LATE WEDNESDAY INTO EARLY THURSDAY. IT WILL BE FAIR AND WARMER TOWARD THE END OF THE WEEK UNDER HIGH PRESSURE. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES. STRONGER ONSHORE FLOW AND A COASTAL HAS BEEN RESPONSIBLE FOR THE LACK OF CLEARING NEAR THE COAST AND THE DEEPENING MARINE LAYER UP PAST 2500 FEET. MORE OF THE SAME WEATHER IS EXPECTED MON WITH FULL COASTAL BASIN COVERAGE OF LOW CLOUDS TONIGHT UP TO 3000 FEET. TEMPS WILL NOT CHANGE MUCH EXCEPT IN THE INTERIOR WHERE THE LOW PRESSURE WILL CONTINUE TO BRING TEMPS DOWN. A LOW PRESSURE TROUGH MOVES INTO SOCAL LATE TUE AND EARLY WED AND THIS WILL BRING SHOWERS AND WIND. LATEST MODEL RUNS HAVE ANOTHER SHORTWAVE FROM THE NORTH THAT SLIDES DOWN INTO THE TROUGH AND TURNS IT INTO A SLOW MOVING CUTOFF LOW OVER THE NORTHWEST CORNER OF MEXICO. THIS INTRODUCES MORE UNCERTAINTY IN THE TIMING AND INTENSITY OF ALL WEATHER ELEMENTS. INITIALLY THE LOW WILL WRING OUT HEAVY DRIZZLE AND LIGHT SHOWERS OUT OF THE MARINE LAYER TUE...THEN GENERATE SHOWERS IN ALL AREAS (EXCEPT PROBABLY NOT DESERTS) TUE EVE THROUGH WED. BY WED EVE THE CURRENT SOLUTION SHOVES THE MOISTURE EASTWARD AS THE CUTOFF LOW DEVELOPS...BUT MORE WIND AND COLD AIR ARRIVE TOO. THE BEST CHANCES OF PRECIP ARE TUE EVE THROUGH WED EVE...BUT AMOUNTS REMAIN SMALL AND SHOULD BE BELOW 0.25 INCH. THE STRONGEST WINDS ARE EXPECTED TUE AFTERNOON THROUGH THU MORNING STARTING FROM THE SOUTHWEST AND SHIFTING GRADUALLY NORTH BY WED NIGHT. AS THE LOW DRIFTS EASTWARD...A NICE UPPER RIDGE BUILDS FROM THE WEST AS THE LOW CAMPS OUT IN MEXICO ON THU THROUGH SAT. SO TEMPS WILL REBOUND AND THE MARINE LAYER WILL GET SQUASHED BACK TO ONLY THE COAST. THE JET STREAM OVER THE EASTERN PACIFIC SAGS SOUTHWARD EARLY NEXT WEEK PUTTING CA IN STRONGER ZONAL FLOW...BUT THE MOISTURE REMAINS WAY TOO FAR NORTH FOR ANY CHANCE OF PRECIP IN SOCAL. && .AVIATION... 182100Z...ACARS SOUNDINGS INDICATE THE MARINE LAYER HAD DEEPENED TO ALMOST 3000 FEET SINCE THIS MORNING. A WEAK COASTAL EDDY APPEARS TO BE HELPING TO DEEPEN THE MARINE LAYER. STRATUS...WITH BASES AROUND 1500 FEET MSL...SHOULD PUSH BACK INLAND THIS EVENING AND PENETRATE A LITTLE FURTHER INLAND THAN LAST NIGHT. MOST COASTAL AIRPORTS SHOULD HAVE MVFR CATEGORY CEILINGS WITH SOME IFR CEILINGS EXPECTED AT MESA AND INLAND AIRPORTS TONIGHT. STRATUS SHOULD PULL BACK TO THE COAST...AGAIN...BY EARLY AFTERNOON ON MONDAY. ABOVE THE MARINE LAYER...VFR CONDITIONS SHOULD CONTINUE THROUGH MONDAY WITH VARIABLE AMOUNTS OF CIRRUS ABOVE FL200 AND UNRESTRICTED VISIBILITIES. && .SGX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...MM AVIATION/MARINE...HORTON
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
900 AM PDT SUN MAR 18 2007 .SYNOPSIS... UPPER LEVEL LOW PRESSURE WILL CONTINUE TO BRING FAIR WEATHER THROUGH MONDAY WITH LOW CLOUDS...FOG AND PATCHY DRIZZLE WEST OF THE MOUNTAINS IN THE NIGHTS AND MORNINGS. THE LOW WILL MOVE THROUGH TUESDAY EVENING AND WEDNESDAY MORNING BRINGING A CHANCE OF SHOWERS AND STRONG WINDS MAINLY TO THE MOUNTAINS AND DESERTS. DRIER NORTHWEST FLOW ARRIVES WEDNESDAY AFTERNOON THROUGH THURSDAY. IT WILL BE FAIR AND WARMER TOWARD THE END OF THE WEEK UNDER HIGH PRESSURE. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES. THE LOW CLOUDS FILLED THE ENTIRE COASTAL BASIN UP TO ABOUT 2500 FEET THIS MORNING. PATCHY DRIZZLE WAS AROUND AND DENSE FOG ONLY OCCURRED ON THE INLAND EDGE OF THE CLOUD DECK. THE CLOUDS OVER LAND WILL PROBABLY BE SLOWER TO CLEAR THAN THEY WERE YESTERDAY...BUT THE WEAKER MARINE INVERSION TODAY MAY ALLOW BEACHES TO CLEAR AS WELL. MORE OF THE SAME WEATHER IS EXPECTED MON WITH FULL COASTAL BASIN COVERAGE OF LOW CLOUDS TONIGHT. A WEAK COASTAL EDDY COULD DEVELOP TO ASSIST THE LOW CLOUDS ON THEIR INLAND QUEST. TEMPS WILL NOT CHANGE MUCH EXCEPT IN THE INTERIOR WHERE THE LOW PRESSURE WILL HELP BRING TEMPS DOWN WELL BELOW THE RECENT RECORD LEVELS. A LOW PRESSURE TROUGH SENDS A SHORTWAVE THROUGH SOCAL LATE TUE AND EARLY WED. THIS IS A SLOWER SOLUTION THAN RECENT MODEL RUNS HAD IT. ALSO DIFFERENT IS THAT THE MAIN ENERGY AND JET SEEM TO GO INTO BAJA NOW AND THE UPPER LOW CUTS OFF OVER SONORA AND AZ. THIS ACTION STOPS THE EASTWARD PROGRESSION OF THE LOW...PUTTING SOCAL IN NORTHEAST FLOW LATE WED THROUGH FRI. SO PRECIP NOW APPEARS MOST LIKELY LATE TUE AFTERNOON THROUGH WED AFTERNOON...BUT AMOUNTS WILL STILL BE ON THE LIGHT SIDE BELOW ONE QUARTER INCH. THE STRONGEST WINDS ARE EXPECTED DURING THE SAME TIME STARTING FROM THE SOUTHWEST AND SHIFTING NORTHWEST AND NORTH ON WED AND THU. AN UPPER RIDGE BUILDS NICELY FROM THE WEST AS THE LOW CAMPS OUT IN MEXICO ON THU THROUGH SAT. SO TEMPS WILL REBOUND AND THE MARINE LAYER WILL GET SQUASHED BACK TO ONLY THE COAST. THE JET STREAM OVER THE EASTERN PACIFIC SAGS SOUTHWARD EARLY NEXT WEEK PUTTING CA IN STRONGER ZONAL FLOW...BUT THE MOISTURE WAY TOO FAR NORTH FOR ANY CHANCE OF PRECIP IN SOCAL. && .AVIATION... 181500Z...MORNING ACARS SOUNDINGS AND TOP REPORTS INDICATE THE MARINE LAYER HAD DEEPENED TO AROUND 2500 FEET OVERNIGHT. BASES WERE RUNNING ABOUT 1300 FEET MSL. STRATUS IS THICKER THAN THE PAST COUPLE DAYS SO EXPECT A SLOWER BURN OFF BUT INVERSION ABOVE THE MARINE LAYER IS NOT AS STRONG AS THE PAST COUPLE OF DAYS SO EXPECT BETTER CLEARING NEAR THE COAST. STRATUS SHOULD BEGIN TO BURN OFF BEGINNING ALONG THE EASTERN EDGES WITHIN AN HOUR OR TWO AFTER SUNRISE THEN CLEAR BACK TO THE COAST BY LATE MORNING OR EARLY AFTERNOON. STRATUS SHOULD THEN PUSH BACK INLAND THIS EVENING. A COASTAL EDDY IS EXPECTED TO DEVELOP TODAY WHICH SHOULD HELP DEEPEN THE MARINE LAYER A LITTLE FURTHER THROUGH TONIGHT SO A LITTLE FURTHER INLAND PENETRATION IS EXPECTED. ABOVE THE MARINE LAYER...VFR CONDITIONS SHOULD CONTINUE THROUGH MONDAY WITH VARIABLE AMOUNTS OF CIRRUS ABOVE FL200 AND UNRESTRICTED VISIBILITIES. && .SGX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...MM AVIATION/MARINE...HORTON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
955 AM EDT SUN MAR 18 2007 .UPDATE...MINIMAL SHORT TERM UPDATE. RADAR/SATELLITE TRENDS AND WEB CAM FROM MUNISING INDICATE LK EFFECT FLURRIES ARE DONE. INVERSION OFF TAMDAR FM KSAW SHOWED INVERSION AROUND H95 AND TEMPS AT H95 ARE WARMING THROUGH AFTN SO THIS ALONG WITH DISORGANIZED WIND FIELD WILL LEAD TO NO ADDITIONAL LK EFFECT PCPN. NEXT CONCERN ARE WINDS. EXPECT SHARP/SHALLOW INVERSION TO MIX OUT BY LATE MORNING. SFC RIDGE IS STILL OVER EAST HALF OF CWA THROUGH MOST OF AFTN THOUGH. PUT SOME GUSTS INTO WIND GRIDS OVR FAR WEST NEAR KIWD WITH RETURN FLOW BECOMING ESTABLISHED THERE. OTHERWISE...LIGHT WINDS PREVAIL WITH RIDGE IN VCNTY. UPSTREAM...SNOW AND EVEN A BIT OF LGT RAIN IS DEVELOPING QUICKLY ACROSS FAR NORTHERN NORTH DAKOTA AND ADJACENT PORTIONS OF SCNTRL CANADA AHEAD OF SFC LOW OVR SOUTHERN SASKATCHEWAN. 12Z RAOBS SHOW STRONG WARM AIR ADVECTION PATTERN WITH H85 TEMP VARYING FM +18C AT RAPID CITY TO -8C AT INTERNATIONAL FALLS MN. MAIN SHORTWAVE PROJECTED TO HEAD SE SO NO RAIN ISSUES SHOULD DEVELOP HERE. HOWEVER...WE WILL BE LOOKING AT SNOW AMOUNTS WITH THE SYSTEM THIS AFTN. NO CHANGES TO GOING HEADLINES RIGHT NOW. && .PREV DISCUSSION (409 AM EDT)... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED ZONAL FLOW ALONG THE U.S./CANADIAN BORDER INTO SOUTH CENTRAL CANADA...WHICH THEN DIVES SOUTHEAST INTO A LARGE TROUGH COVERING THE EASTERN THIRD OF THE U.S.. WITHIN THE ZONAL FLOW...THERE ARE TWO FEATURES OF INTEREST. THE FIRST IS A SHRTWV MOVING THROUGH WESTERN WASHINGTON STATE. DPVA AHEAD OF THESE SHRTWVS...COMBINED WITH THE DOWNSLOPING UPPER LEVEL FLOW OFF THE ROCKIES...HAS RESULTED IN LOW PRESSURE CENTERS IN SOUTHERN AND NORTHERN SASKATCHEWAN. WARM ADVECTION AHEAD OF THE LOWS HAS HELPED PULL DEWPOINTS INTO THE MID 30S ACROSS THE DAKOTAS...ALONG WITH RAISING 850MB TEMPS AT 00Z TO 0C AT BIS AND 12C AT GGW. 00Z BIS SOUNDING ALSO SHOWS AN INCREASE IN MOISTURE ABOVE THE SURFACE...WITH PRECIPITABLE WATER OF 0.54 INCHES AND DEWPOINT DEPRESSIONS NO MORE THAN 5C. CLOSER TO HOME...BEING NEAR THE INFLECTION POINT ON THE WEST SIDE OF THE EASTERN TROUGH... ANTICYCLOGENESIS CONTINUES AT THE SURFACE. CURRENTLY...A 1025MB HIGH PRES RIDGE EXTENDS FROM NORTHERN ONTARIO DOWN TO NEW ORLEANS. DRY AIR ASSOCIATED WITH THE RIDGE (PRECIPITABLE WATER OF 0.15 INCHES AT GRB) HAS KEPT SKIES MOSTLY CLEAR ACROSS MUCH OF THE AREA...THOUGH A FEW HIGH CLOUDS MOVING THROUGH THE FLOW ARE MOVING INTO THE WESTERN U.P.. A FEW LAKE EFFECT CLOUDS ARE ALSO COMING OFF EASTERN LAKE SUPERIOR TOO. THE CLEARING...LIGHT WINDS AND DRY AIR WITH THE RIDGE HAS ALLOWED TEMPERATURES TO FALL INTO THE SINGLE DIGITS IN THE INTERIOR. MAIN FORECAST CONCERNS ARE SNOWFALL AMOUNTS TONIGHT...THEN SHIFTS TO WIND ON MONDAY...AND FINALLY POSSIBLE HYDRO CONCERNS WITH STRONG WARM ADVECTION MID-WEEK. MODELS...MODEL AGREEMENT REGARDING THE TWO SHRTWVS OF INTEREST...AND THE IMPACTS ON THE QPF FIELDS AND THE SURFACE PATTERN...IS VERY GOOD. THEREFORE PLAN ON FOLLOWING THE NAM FOR DETAILS. TODAY...MUCH OF THE DAY LOOKS TO BE QUIET AS UPPER MICHIGAN IS PROGGED TO REMAIN UNDER THE INFLUENCE OF DRY AIR ASSOCIATED WITH THE SURFACE RIDGE. UPSTREAM...THE CURRENT ZONAL FLOW INTO SOUTH CENTRAL CANADA IS EXPECTED TO AMPLIFY AS A RESULT OF AN EAST PACIFIC TROUGH MOVING TOWARDS THE WEST COAST. THIS AMPLIFICATION WILL CAUSE THE SHRTWV OVER NORTHERN ALBERTA TO DIG INTO CENTRAL MANITOBA BY 00Z...WHILE THE SHRTWV OVER WESTERN WASHINGTON MOVES EAST TO EASTERN NORTH DAKOTA. THE COMBINATION OF DPVA AHEAD OF THE WESTERN WASHINGTON SHRTWV...SOME UPPER LEVEL DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 90 KT JET OVER WESTERN LOWER MICHIGAN AND ISENTROPIC LIFT SHOULD HELP DEVELOP AN AREA OF MODERATE SNOW THIS AFTERNOON ACROSS NORTHERN MINNESOTA...WHICH MAY REACH WESTERN LAKE SUPERIOR LATE IN THE DAY. THE REST OF THE CWA WILL EXPERIENCE AN INCREASE IN MID AND HIGH CLOUDS THROUGH THE DAY. DESPITE THE INCREASE IN CLOUDS...THERE SHOULD STILL BE ENOUGH SUNSHINE TO ALLOW TEMPERATURES TO CLIMB INTO THE 30S AGAIN. WITH A SOUTHERLY WIND DEVELOPING IN THE WESTERN U.P....A FEW SITES THERE MAY GET CLOSE TO 40 THANKS TO DOWNSLOPING. TONIGHT...SHRTWV TROUGH OVER CENTRAL MANITOBA IS PROGGED TO DIG DOWN INTO NW ONTARIO BY 12Z...CAUSING THE SHRTWV OVER EASTERN NORTH DAKOTA TO MOVE INTO UPPER MICHIGAN AFTER MIDNIGHT. THEREFORE...THE MODERATE SNOW AREA OVER NORTHERN MINNESOTA IS EXPECTED TO CROSS UPPER MICHIGAN THROUGH THE NIGHT. SINCE THERE IS GOOD AGREEMENT... AND THAT THE UPSTREAM AIRMASS IS ALREADY FAIRLY MOIST (PARTICULARLY NEAR BIS) WILL RAISE POPS TO CATEGORICAL. IT APPEARS A DRY SLOT MOVING IN WILL HELP END THE PRECIPITATION OVER WESTERN LAKE SUPERIOR AND THE FAR WESTERN U.P. BETWEEN 10-12Z. AS FAR AS AMOUNTS GO...SOUNDINGS LOOK FAVORABLE FOR DECENT SNOWFALL...SHOWING STRONG VERTICAL MOTION INTERSECTING A 2000-3000 FT DENDRITIC GROWTH LAYER (LAYER LOCATED BETWEEN 12000-14000FT)...ALONG WITH A DEEP AGGREGATION LAYER (SURFACE TO 7000 FT). NAM/GFS QPF AMOUNTS SUGGEST AROUND 0.5 INCH...WHICH GIVEN THE FAVORABLE PARAMETERS FOR GOOD SIZE SNOWFLAKES...AT LEAST A 12 TO 1 SNOWFALL RATIO CAN BE USED. THIS RESULTS IN AMOUNTS AT HIGH END ADVISORY. DAY SHIFT WILL NEED TO MONITOR SNOWFALL RATIOS THAT OCCUR UPSTREAM TODAY. IF THE SNOWFALL RATIOS END UP HIGHER THAN FORECAST...OR THERE IS MORE QPF EXPECTED...THE ADVISORIES MAY BE UPGRADED TO WARNINGS. PREVIOUS LOW TEMPERATURE FORECAST LOOKS REASONABLE...ESPECIALLY SINCE ALL THE CLOUD COVER AND A DECENT SOUTHERLY WIND SHOULD KEEP READINGS ABOVE MAV/MET GUIDANCE. ON THE NOTE OF A DECENT SOUTHERLY WIND...NOT ONLY HAVE THE PCPN AMOUNTS INCREASED...BUT ALSO THE WIND SPEEDS. THE NAM SHOWS A 60 KT LOW LEVEL JET AT 3000 FT COMING ACROSS...WHICH RESULTS IN WIND SPEEDS ON EASTERN LAKE SUPERIOR NEAR THE SURFACE BETWEEN 25-30 KT. ALTHOUGH WARM ADVECTION IS OCCURRING...SOME GALES TO 35 KT SHOULD BE POSSIBLE ON EASTERN LAKE SUPERIOR SINCE 850MB TEMPS ONLY CLIMB INTO -5C. MONDAY...SHRTWV TROUGH OVER NW ONTARIO IS EXPECTED TO CONTINUE DIGGING ACROSS NORTHERN ONTARIO...THOUGH ALSO MOVING QUICKLY EAST. 850MB TEMPS QUICKLY FALLING INTO THE -20S C BEHIND THE TROUGH RESULTS IN STRONG BAROCLINICITY...THUS THE ASSOCIATED SURFACE LOW ENDS UP DEEPENING TO 993MB WHEN IT REACHES HALF WAY BETWEEN WAWA AND JAMES BAY BY 18Z. THEREFORE...WITH THE PASSAGE OF THE COLD FRONT...WINDS WILL CONTINUE TO INCREASE THROUGH THE DAY WHILE TURNING NW. BETWEEN 18-21Z...NW GALES OF 40-45 KT LOOK LIKE A GOOD BET ON EASTERN LAKE SUPERIOR. A WIND ADVISORY MAY BE NEEDED FOR THE KEWEENAW PENINSULA AND ALGER AND LUCE COUNTIES WHICH ARE MORE EXPOSED TO THE NW WIND. AS FAR AS PCPN CHANCES GO...SNOW AHEAD OF THE COLD FRONT OVER THE EASTERN CWA SHOULD QUICKLY MOVE OFF INTO ONTARIO BY NOON. AFTER THAT...THE DRY SLOT MOVING IN...ALONG WITH BEING ON THE SW SIDE OF THE STRONG SHRTWV TO THE NORTH SHOULD PREVENT ANY MORE SYNOPTIC PCPN. ALTHOUGH THE NW WINDS WILL BE ADVECTING IN UNSEASONABLY COLD AIR LATE IN THE DAY...WITH 850MB TEMPS DROPPING TO -15 TO -20C ACROSS THE CWA BY 00Z...THE OVERALL ATMOSPHERE IS PROGGED ON SOUNDINGS TO BE VERY DRY. THEREFORE...LAKE EFFECT SNOW...AND EVEN LAKE EFFECT CLOUDS...MAY TAKE AWHILE TO DEVELOP. IT APPEARS THAT PERHAPS AFTER 18Z WE SHOULD SEE LAKE EFFECT CLOUDS INCREASE...AND ESPECIALLY AFTER 21Z OVER EASTERN LAKE SUPERIOR WITH A LONGER FETCH. MONDAY NIGHT AND TUESDAY...MODELS SHOW THE EAST PACIFIC TROUGH MOVING ONSHORE INTO THE WEST COAST TUESDAY MORNING...RESULTING IN DOWNSTREAM RIDGING AHEAD OF IT INTO THE PLAINS. THIS BUILDING UPPER RIDGE WILL HELP PUSH MONDAYS SHRTWV TROUGH QUICKLY OFF TO THE EAST...ALLOWING A SURFACE HIGH FROM CENTRAL CANADA TO BUILD INTO FAR NORTHERN LAKE SUPERIOR BY 12Z TUE. CONTINUED DRY AIR ADVECTION COMBINED WITH SUBSIDENCE BEHIND THE SHRTWV TROUGH SHOULD GRADUALLY CLEAR THE SKIES OUT...ESPECIALLY AWAY FROM LAKE SUPERIOR. LOWERED TEMPERATURES IN THE INTERIOR WEST HALF TO JUST BELOW ZERO SINCE WINDS ARE PROGGED TO GO LIGHT AND PRECIPITABLE WATER FALLS TO AROUND 0.20 OF AN INCH. ON TUESDAY...THE SURFACE HIGH SLIPS OFF INTO QUEBEC BY 00Z...RESULTING IN WARM ADVECTION AGAIN. IN FACT...THE ADVECTION IS QUITE IMPRESSIVE...WITH 850MB TEMPS WARMING ALMOST 10C. HOWEVER...THIS WARMING IS NOT SEEN AS MUCH AT THE SURFACE GIVEN THAT THE SURFACE FLOW IS OUT OF THE SE...INSTEAD OF SW LIKE AT 850MB. THEREFORE...THE MET GUIDANCE ONLY SHOWS A HIGH OF 20 AT SAW. BELIEVE THIS MIGHT BE A BIT COOL...BUT WITH 850MB TEMPS ONLY BETWEEN -8C WEST AND -12C EAST AND MID CLOUDS PASSING THROUGH IN THE WARM ADVECTION PATTERN...HAD TO LOWER TEMPERATURES ABOUT 5 DEGREES. TUESDAY NIGHT THROUGH THURSDAY...THE PROGGED PATTERN CHANGE IS STILL SHOWN...WITH THE DEVELOPMENT OF A SPLIT WESTERN TROUGH AND A SUBSTANTIAL EASTERN RIDGE. THUS...THE ROLLER COASTER OF WEATHER CONTINUES. MODELS SHOW A FAIRLY STRONG LOW PRESSURE TROUGH DEVELOPING OVER THE PLAINS TUESDAY NIGHT (1000MB) WHICH RESULTS IN A TIGHT PRESSURE GRADIENT TO THE SURFACE HIGH THAT EXITED OUR AREA ON TUE. IN FACT...THERE COULD BE ANOTHER SOUTHERLY GALE ON LAKE SUPERIOR WITH THIS. NONETHELESS...THE BREEZY SOUTHERLY WINDS KEEPING THE SURFACE LAYER MIXED AND 850MB TEMPS RISING TO 6C BY 12Z WED SHOULD PREVENT TEMPS FROM FALLING TUESDAY NIGHT. CONTINUED WARM ADVECTION IS PROGGED THROUGH WEDNESDAY NIGHT UNTIL THE TROUGH CROSSES THURSDAY...THUS TEMPERATURES SHOULD JUST CONTINUE RISING. HOW MUCH IS STILL UNCERTAIN AT THIS POINT. RAIN SHOWERS ALSO LOOK FAVORABLE STARTING WEDNESDAY AFTERNOON AND CONTINUING INTO WEDNESDAY NIGHT AS A WARM FRONT OVER THE OHIO VALLEY LIFTS NORTHWARD ACROSS THE CWA. SHOWALTER INDICIES DROP BELOW ZERO TOO...SO ADDED THE POSSIBILITY FOR THUNDERSTORMS. AS FAR AS AMOUNTS GO...THE GFS SHOWS PRECIPITABLE WATER CLIMBING TO AROUND 1 INCH...WHICH IS AROUND 300 PERCENT OF NORMAL! DEPENDING ON HOW THINGS SET UP...SOME PLACES COULD GET AN INCH OF RAIN. SINCE THERE SEEMS TO BE GREAT AGREEMENT BOTH AMONGST MODELS AND THEIR PREVIOUS RUNS...HAVE RAISED POPS FOR WEDNESDAY NIGHT. QUESTIONS STILL REMAIN ON HOW QUICK THE COLD FRONT WILL CROSS THURSDAY. WILL CONTINUE TO MENTION THE POSSIBILITY OF FLOODING FROM ICE JAMS IN THE HWO. NO CHANGES MADE BEYOND THU. PATTERN CONTINUES TO LOOK SPRING-LIKE. IF THE 00Z ECMWF IS RIGHT...SHOWING EXTRA AMPLIFICATION OF THE RIDGE ON SATURDAY...HIGH TEMPERATURES THAT DAY COULD CLIMB WELL INTO THE 60S. COORDINATED WITH DLH...GRB...APX AND ENVIRONMENT CANADA IN TORONTO. && .MQT WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY 8 PM EDT TONIGHT TO 8 AM EDT MONDAY MIZ001>004-009-010-084. SNOW ADVISORY 11 PM EDT TONIGHT TO 10 AM EDT MONDAY MIZ005-006-011>013. SNOW ADVISORY 1 AM EDT TONIGHT TO 11 AM EDT MONDAY MIZ007-014-085. GALE WARNING WEST HALF LAKE SUPERIOR FOR MONDAY. GALE WARNING EAST HALF LAKE SUPERIOR LATE TONIGHT THROUGH LATE MONDAY NIGHT. && $$ UPDATE...JLA PREV DISCUSSION...AJ
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
300 AM MDT SUN MAR 18 2007 .DISCUSSION... A SLEW OF RECORDS TO BE TIED OR BROKEN AGAIN TODAY STATEWIDE. 08Z SFC ANALYSIS SHOWS A 1009MB LOW PRES CENTER OVER SE CO WITH A LEE TROUGH EXTENDING SW ACROSS THE E PLAINS. WATER VAPOR LOOP SHOWS A LARGE RIDGE MOVING EAST ACROSS THE INTERMOUNTAIN WEST WITH A SHORTWAVE DISTURBANCE EMBEDDED IN THE RIDGE OVER AZ/NM. 400-250MB AIRCRAFT WIND DATA SHOWS VERY LIGHT WINDS IN THE UPPER LEVELS OVER MUCH OF THE DESERT SW EXCEPT FOR A 40-60 KNOT JET IN THE BASE OF THE SHORTWAVE TROUGH OVER AZ. 00Z MREF/03Z SREF IN GOOD AGREEMENT THAT THE SHORTWAVE OVER AZ WILL TRANSLATE SLOWLY EAST BENEATH THE WESTERN CONUS RIDGE THROUGH EARLY MONDAY. WEAK DYNAMICS ALOFT AND STRONG SFC HEATING WILL ACT TO SQUEEZE OUT A FEW ISOLATED SHOWERS/TSTMS IN THE SE LATE THIS AFTERNOON AS THE SHORTWAVE CROSSES THE REGION. LEE TROUGHING IS EXPECTED TO BE STRONGER TODAY THAN SATURDAY SO TEMPS WILL WARM INTO THE MID TO UPPER 80S IN MANY AREAS IN THE EAST DESPITE MID AND HIGH LEVEL CLOUDS. STRONGER MIXING IN THE WEST WILL ALSO RAISE TEMPS INTO THE 70S TO AROUND 80 IN MANY LOCATIONS WITH THE RECORD OF 77F AT KABQ IN JEOPARDY. A WEAK COLD FRONT WILL MOVE ACROSS THE NE PLAINS BEHIND THIS SHORTWAVE SUNDAY NIGHT COOLING TEMPS TO MORE SEASONAL LEVELS MONDAY. ANOTHER SHORTWAVE CURRENTLY OFF THE CA COAST WILL MOVE EAST ACROSS NM MONDAY AND HELP FORCE THE COLD FRONT SOUTH ACROSS THE E PLAINS AS IT PASSES INTO TX MONDAY NIGHT. MODEL PWATS AROUND 0.5 INDICATE SUFFICIENT MOISTURE BEHIND THE FRONT FOR SHOWERS AND TSTMS WITH LIFTED INDICES AVERAGING -1 TO -2C AND 700-500MB LAPSE RATES PUSHING -10C/KM. TEMPS WILL REMAIN ABOVE AVERAGE IN THE WEST MONDAY BUT FALL BACK TO SEASONAL NORMALS TUESDAY WITH INCREASING CLOUDS AHEAD OF A MORE SUBSTANTIAL SYSTEM FOR MIDWEEK. CHALLENGE IN THE EXTENDED WILL BE WHEN THE BEST CHANCE FOR PRECIP DEVELOPS AS MODELS INDICATE LOTS OF UPPER LEVEL ENERGY TO CROSS THE STATE IN SEVERAL DIFFERENT PIECES THROUGH FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 75 37 72 37 / 0 0 0 0 GALLUP.......................... 74 31 69 30 / 0 0 0 0 GRANTS.......................... 75 32 70 30 / 0 0 0 0 GLENWOOD........................ 82 43 77 42 / 0 0 0 0 CHAMA........................... 65 26 59 28 / 0 0 5 10 LOS ALAMOS...................... 71 37 66 34 / 0 0 5 10 RED RIVER....................... 63 27 55 28 / 0 0 10 30 TAOS............................ 71 30 66 32 / 0 0 10 10 SANTA FE........................ 72 36 69 36 / 0 0 5 10 SANTA FE AIRPORT................ 74 38 70 37 / 0 0 5 10 ESPANOLA........................ 78 36 73 38 / 0 0 5 10 ALBUQUERQUE HEIGHTS............. 78 45 75 45 / 0 0 0 5 ALBUQUERQUE VALLEY.............. 80 41 77 43 / 0 0 0 5 ALBUQUERQUE FOOTHILLS........... 77 43 74 43 / 0 0 0 5 ALBUQUERQUE WEST MESA........... 79 44 76 44 / 0 0 0 5 SOCORRO......................... 84 44 78 42 / 0 0 0 0 SANDIA PARK/CEDAR CREST......... 72 40 68 38 / 0 0 0 5 MORIARTY/ESTANCIA............... 75 35 70 36 / 0 0 0 10 CARRIZOZO....................... 80 45 77 44 / 5 0 0 0 RUIDOSO......................... 71 41 69 39 / 10 0 0 0 RATON........................... 78 34 64 35 / 0 0 10 20 LAS VEGAS....................... 77 39 65 37 / 0 0 10 20 ROY............................. 78 42 67 39 / 0 0 10 20 CLAYTON......................... 80 44 65 42 / 0 0 10 30 SANTA ROSA...................... 83 44 77 42 / 0 0 5 20 TUCUMCARI....................... 85 46 74 45 / 0 0 10 30 FORT SUMNER..................... 86 45 78 44 / 10 0 5 20 CLOVIS.......................... 83 48 75 44 / 10 0 5 20 PORTALES........................ 84 46 78 45 / 10 0 5 20 ROSWELL......................... 87 50 85 47 / 10 0 0 5 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ GUYER
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1032 AM CDT SUN MAR 18 2007 .DISCUSSION... WATER VAPOR LOOP SHOWING SHORT WAVE OVER NORTHERN MT MOVING EAST. UPPER RIDGE AXIS EXTENDED FROM THE WESTERN DAKOTAS TO WESTERN NEB WAS ALSO SHIFTING EAST. TAMDAR SOUNDING INDICATE GOOD LOW LEVEL MOISTURE WITH DEWPOINTS AT 850 HPA AROUND 5 TO 6C AT PIR OR ABOUT 5 OR 6C HIGHER THAN MODEL FORECAST. RADAR SHOWING PRECIPITATION DEVELOPING/MOVING INTO NORTHERN ND. CURRENT TEMPERATURES OVER THE SNOW FIELD ARE HIGHER THAN CURRENT FORECAST AND LOWER THAN FORECAST OVER THE SOUTHERN VALLEY. WILL INCREASE TEMPERATURES OVER SNOW FIELD IN THE NORTH. WINDS WERE BRISK OVER EASTERN ND WITH GUSTS IN THE 20 TO 25 KTS RANGE. WITH HIGHER TEMPERATURES MOVING INTO EASTERN ND AND ADJACENT PARTS OF MN...WILL NOT HAVE SNOW ADVISORY GO ANY FARTHER WEST. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...FLASH FLOOD WATCH UNTIL 1 PM CDT THIS AFTERNOON FOR NDZ053. MN...SNOW ADVISORY FROM NOON TODAY TO MIDNIGHT CDT TONIGHT FOR MNZ009- 017. && $$ HOPPES
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
827 PM CDT MON MAR 19 2007 .DISCUSSION... ANOTHER QUIET NIGHT ACROSS SOUTHEAST TEXAS. THE SURFACE PRESSURE GRADIENT IS STILL A BIT TIGHT SO THINKS WINDS WILL NOT FULLY DECOUPLE OVERNIGHT. 850 MB MOISTURE IS TRAPPED BENEATH A STRENGTHENING TEMP INVERSION LOCATED BETWEEN 850-750 MB. AM EXPECTING LOW STRATUS TO DEVELOP AFTER 06Z. WEAK RIDGING IS EVIDENT AT 250 MB. IR IMAGERY SUPPORTS CIRRUS MOVING OVERHEAD THROUGH 09Z. LONG RANGE PROGS KEEP AN APPROACHING UPPER LEVEL LOW WELL WEST OF TEXAS SO THINK RAIN CHANCES WILL HOLD OFF UNTIL LATE IN THE WEEKEND OR EARLY NEXT WEEK. CURRENT FORECAST HAS A GREAT HANDLE ON THINGS AND AN UPDATE IS NOT REQUIRED. 43 && .PREV DISCUSSION... /ISSUED 754 PM CDT MON MAR 19 2007/ AVIATION... THIS IS A SIMILAR FORECAST PATTERN TO THE PAST TWO NIGHTS SO PERSISTENCE PLAYED HEAVY PART OF THOUGHT PROCESS. MODELS ARE IN BETTER AGREEMENT FOR OVER NIGHT CLOUD COVER...HOWEVER I ANTICIPATE THAT MVFR CIGS WILL REMAIN TO THE NORTH AND WEST OF HOUSTON AREA BECAUSE OF STRONGER ONSHORE WINDS CLOSER TO THE COAST. VSBYS SHOULD REMAIN UNLIMITED FOR NEXT 24 HOURS. VFR SKY CONDITIONS SHOULD PREVAIL UNTIL 06-08Z WHEN LOWER CIGS SHOULD REFORM AND DROP TO MVFR LEVELS AT KCLL...KUTS...AND KCXO. AM FORECASTING CIGS TO REMAIN NEAR VFR/MVFR THRESHOLD AT HOUSTON METRO TAF SITES AND CLOSER TO THE COAST. INLAND TAFS SHOULD ALL RETURN TO VFR FLIGHT RULES BETWEEN 15-18Z WITH DAYTIME HEATING. SOUTHERLY WINDS WILL DECREASE TO 5-10 KNOTS OVERNIGHT BEFORE INCREASING TO 15 TO 20 KNOTS DURING THE DAY WEDNESDAY. NOTE...KUTS ASOS IS REPORTING VRB03 AT 2353Z WHILE NEIGHBORING OBSERVATIONS REMAIN THE 15 TO 20 KNOT RANGE. THE KUTS ASOS GETS BLOCKED BY TREES WHEN WINDS ARE FROM THE SOUTH SO THE HIGHER WINDS IN TAF REFLECT WHAT I ANTICIPATE AIRCRAFT TO ENCOUNTER ON THE RUNWAY. 44 PREV DISCUSSION.../ISSUED AT 410 PM CDT MON MAR 19 2007/ MODELS CONTINUING THE DRIER TREND (OF THE PAST COUPLE OF DAYS) WITH THIS RUN AS WELL. THE UPPER LOW TO DEEPEN/REMAIN WELL OUT TO OUR WEST THROUGH THE WEEK BEFORE SCOOTING OFF ON A MORE NLY TRACK OVER THE WEEKEND. THIS PATTERN TO HELP MAINTAIN A DECENT CAP OVER THE AREA FOR MOST OF THE WEEK (AS THE MID-LEVEL WINDS REMAIN OUT OF THE SW). RIDGING ALOFT OVER THE STATE ALONG WITH THE CAP TO WEAKEN BY THE WEEKEND. SO HAVE LOWERED POPS FOR THE WEEK...AND ONLY KEEPING POPS AOA 20 FOR THE END OF THE FCST PD. PERSISTENT CLOUDS (VIA DISTURBANCES EMBEDDED IN THE SRN STREAM JET) TO MAINTAIN THE WARMISH TEMPS OF LATE...SO NO MAJOR JUMPS OR DIPS WITH TEMPS IN THE OFFING. ALL IN ALL A LOT OF THE SAME COMING UP. 41 PREV MARINE.../ISSUED AT 410 PM CDT MON MAR 19 2007/ SEAS WERE NEAR 5 FEET WITH SOUTHEAST WINDS NEAR 10 KNOTS AT BUOY035 AND NEAR 7 FEET WITH SOUTHEAST WINDS NEAR 15 KNOTS AT BUOY019. WILL LET THE SCEC GO FOR THE BAY WATERS TONIGHT AND EXTEND THE OFFSHORE WATER SCEC OUT TO 20 AND 20-60 NM SCA THROUGH 7 PM TOMORROW NIGHT. LOW PRESSURE OVER WEST TEXAS AND HIGH PRESSURE RIDGE OVER THE SOUTHEAST UNITED STATES PROVIDING A RELATIVELY TIGHT PRESSURE GRADIENT OVER THE COASTAL WATERS THROUGH AT LEAST MID-WEEK. SCEC CRITERIA SHOULD PERSIST IN THE OFFSHORE WATERS THROUGH THE WEEK WITH A MODERATE TO STRONG ONSHORE FLOW PERSISTING THROUGH THE PERIOD. HIGH PROBABILITY OF SMALL CRAFT ADVISORIES FOR THE FAR OFFSHORE WATERS THROUGH THURSDAY AS SWELLS REACH SCA CRITERIA WITH THIS PERSISTENT ONSHORE FLOW. 31 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 64 77 64 77 64 / 10 10 10 10 10 HOUSTON (IAH) 64 76 64 76 64 / 10 10 10 10 10 GALVESTON (GLS) 65 73 65 73 65 / 10 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH TUESDAY EVENING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 7 PM CDT TUESDAY FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...43
AREA FORECAST DISCUSSION...UPDATE AVN/MARINE
NWS HOUSTON/GALVESTON TX
754 PM CDT MON MAR 19 2007 .AVIATION... THIS IS A SIMILAR FORECAST PATTERN TO THE PAST TWO NIGHTS SO PERSISTENCE PLAYED HEAVY PART OF THOUGHT PROCESS. MODELS ARE IN BETTER AGREEMENT FOR OVER NIGHT CLOUD COVER...HOWEVER I ANTICIPATE THAT MVFR CIGS WILL REMAIN TO THE NORTH AND WEST OF HOUSTON AREA BECAUSE OF STRONGER ONSHORE WINDS CLOSER TO THE COAST. VSBYS SHOULD REMAIN UNLIMITED FOR NEXT 24 HOURS. VFR SKY CONDITIONS SHOULD PREVAIL UNTIL 06-08Z WHEN LOWER CIGS SHOULD REFORM AND DROP TO MVFR LEVELS AT KCLL...KUTS...AND KCXO. AM FORECASTING CIGS TO REMAIN NEAR VFR/MVFR THRESHOLD AT HOUSTON METRO TAF SITES AND CLOSER TO THE COAST. INLAND TAFS SHOULD ALL RETURN TO VFR FLIGHT RULES BETWEEN 15-18Z WITH DAYTIME HEATING. SOUTHERLY WINDS WILL DECREASE TO 5-10 KNOTS OVERNIGHT BEFORE INCREASING TO 15 TO 20 KNOTS DURING THE DAY WEDNESDAY. NOTE...KUTS ASOS IS REPORTING VRB03 AT 2353Z WHILE NEIGHBORING OBSERVATIONS REMAIN THE 15 TO 20 KNOT RANGE. THE KUTS ASOS GETS BLOCKED BY TREES WHEN WINDS ARE FROM THE SOUTH SO THE HIGHER WINDS IN TAF REFLECT WHAT I ANTICIPATE AIRCRAFT TO ENCOUNTER ON THE RUNWAY. 44 && .PREV DISCUSSION.../ISSUED AT 410 PM CDT MON MAR 19 2007/ MODELS CONTINUING THE DRIER TREND (OF THE PAST COUPLE OF DAYS) WITH THIS RUN AS WELL. THE UPPER LOW TO DEEPEN/REMAIN WELL OUT TO OUR WEST THROUGH THE WEEK BEFORE SCOOTING OFF ON A MORE NLY TRACK OVER THE WEEKEND. THIS PATTERN TO HELP MAINTAIN A DECENT CAP OVER THE AREA FOR MOST OF THE WEEK (AS THE MID-LEVEL WINDS REMAIN OUT OF THE SW). RIDGING ALOFT OVER THE STATE ALONG WITH THE CAP TO WEAKEN BY THE WEEKEND. SO HAVE LOWERED POPS FOR THE WEEK...AND ONLY KEEPING POPS AOA 20 FOR THE END OF THE FCST PD. PERSISTENT CLOUDS (VIA DISTURBANCES EMBEDDED IN THE SRN STREAM JET) TO MAINTAIN THE WARMISH TEMPS OF LATE...SO NO MAJOR JUMPS OR DIPS WITH TEMPS IN THE OFFING. ALL IN ALL A LOT OF THE SAME COMING UP. 41 && .PREV MARINE.../ISSUED AT 410 PM CDT MON MAR 19 2007/ SEAS WERE NEAR 5 FEET WITH SOUTHEAST WINDS NEAR 10 KNOTS AT BUOY035 AND NEAR 7 FEET WITH SOUTHEAST WINDS NEAR 15 KNOTS AT BUOY019. WILL LET THE SCEC GO FOR THE BAY WATERS TONIGHT AND EXTEND THE OFFSHORE WATER SCEC OUT TO 20 AND 20-60 NM SCA THROUGH 7 PM TOMORROW NIGHT. LOW PRESSURE OVER WEST TEXAS AND HIGH PRESSURE RIDGE OVER THE SOUTHEAST UNITED STATES PROVIDING A RELATIVELY TIGHT PRESSURE GRADIENT OVER THE COASTAL WATERS THROUGH AT LEAST MID-WEEK. SCEC CRITERIA SHOULD PERSIST IN THE OFFSHORE WATERS THROUGH THE WEEK WITH A MODERATE TO STRONG ONSHORE FLOW PERSISTING THROUGH THE PERIOD. HIGH PROBABILITY OF SMALL CRAFT ADVISORIES FOR THE FAR OFFSHORE WATERS THROUGH THURSDAY AS SWELLS REACH SCA CRITERIA WITH THIS PERSISTENT ONSHORE FLOW. 31 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 64 77 64 77 64 / 10 10 10 10 10 HOUSTON (IAH) 64 76 64 76 64 / 10 10 10 10 10 GALVESTON (GLS) 65 73 65 73 65 / 10 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY. SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH TUESDAY EVENING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 7 PM CDT TUESDAY FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
320 AM PDT TUE MAR 20 2007 .SHORT TERM... FORECAST CONFIDENCE HAS DETERIORATED CONSIDERABLY SINCE YDY. VERY WEAK AND DIFFUSE FRONT APPROACHING THE BAY AREA NOW. IT WILL REACH THE CENTRAL COAST THIS AFTERNOON AND AREAS SOUTH OF POINT CONCEPTION LATER THIS AFTERNOON AND EVENING. HOW WELL THE FRONT HOLDS TOGETHER IS SOMEWHAT OF A PUZZLE. GFS IS THE MORE ROBUST MDL BUT 06Z WRF HAS TRENDED A LITTLE WETTER. ACARS SHOWS MARINE LAYER AT 2500 FEET AND WITH A 6 PLUS MB ONSHORE PUSH CLOUDS AGAIN COVER ALL COASTS AND VLYS AND EXTEND DEEP INTO THE MOUNTAIN PASSES. THERE WILL BE A CHANCE OF SOME DRIZZLE IN THE FOOTHILLS AND MOUNTAINS. WHILE ASSIGNING THE EXACT POP VALUE TO THE RAIN IS DIFFICULT FORECASTING THE AMOUNT OF RAIN POTENTIAL IS NOT SINCE THIS IS A FAIRLY DRY AND UNINSPIRED SYSTEM AT MOST A QUARTER INCH WILL FALL AND MORE LIKELY A TENTH. AS USUAL THE CENTRAL COAST WILL HAVE BOTH THE GREATEST CHANCE OF RAIN AS WELL AS THE GREATEST POTENTIAL FOR THE MOST RAINFALL. THE UPPER TROF MOVES OVERHEAD TONIGHT AND WILL BRING A CHANCE OF RAIN WITH IT...ALTHOUGH THE CHANCES FOR THE CENTRAL COAST WILL DIMINISH AFTER EVENING. WEDNESDAY THE UPPER TROF DOES NOT PROGRESS RATHER IT IS FORECAST TO PINCH OFF INTO AN UPPER LOW AND PLUNGE QUICKLY SOUTHWARD. WHAT THIS SCENARIO WILL DO IS SOMEWHAT HARD TO PREDICT, IT LOOKS LIKE THERE WILL BE ENOUGH WRAP AROUND AND DYNAMICS FOR A FURTHER CHANCE OF SHOWERS SOUTH OF POINT CONCEPTION...IF THE UPPER LOW MOVES A LITTLE SLOWER IT WILL INCREASE THE POTENTIAL FOR THUNDERSTORMS AND THIS WILL HAVE TO BE WATCHED. UNDERNEATH THE UPPER LOW LOW LEVEL NORTH FLOW WILL BUNCH CLOUDS UP ALONG THE NORTH SLOPES AND ALSO CREATE A SLIGHT CHANCE OF SHOWERS THERE. THINGS SHOULD CLEAR OUT WEDNESDAY AFTERNOON AS THE LOW MOVES FURTHER SOUTH AND OUT OF REACH OF THE LOX CWA. AS THE LOW SLIDES SOUTH IT ALSO TURNS THE UPPER LEVEL FLOW OFFSHORE. COINCIDENT WITH THIS IS A HIGH MOVING INTO THE GREAT BASIN. BOTH OF THESE WILL COMBINE TO PRODUCE A DECENT OFFSHORE EVENT. IF THINGS GO AS PLANNED WIND ADVISORIES WILL BE NEEDED IN THE MOUNTAINS AND SOME VALLEY LOCATIONS. .LONG TERM... DRY NORTHWEST FLOW TURNS INTO A WEAK RIDGE SATURDAY. FLOW TURNS ONSHORE SO WHILE MOST AREAS WILL WARM EACH DAY THE COASTAL AREAS WILL COOL OR REMAIN ABOUT THE SAME. THE ONSHORE FLOW INCREASES SAT NIGHT AND THE RIDGE SHOULD PROVIDE ENOUGH WARMING ALOFT TO CREATE A DECENT MARINE LAYER SUNDAY. BOTH THE GFS AND EC INDICATE SOME SORT OF STORM ACTIVITY NEXT MON OR TUE. THE EC IN FACT LOOKS PRETTY DECENT ON TUESDAY. TIME WILL TELL HOWEVER ON THIS THE DRIEST YEAR TO DATE AND FOR NOW INCREASED THE CLOUDS AND COOLED THE TEMPS. && .AVIATION... 20/1140 MORNING MARINE LAYER DEPTH RUNNING AROUND 3000-3500 FT...BUT WITH SOMEWHAT DISORGANIZED AREAL PATTERN AS CLOUDS SOCKED IN OVER COASTAL AND VALLEY SECTIONS OF SLO/SBA/VTU COUNTIES BUT LIMITED COVERAGE OVER LAX COUNTY. OVERALL...EXPECT CEILINGS AT ALL COASTAL/COASTAL VALLEY TAFS SITES THIS MORNING WITH CEILING HEIGHTS BETWEEN 2500 AND 3500 FT WHILE VSBYS REMAIN AT 4 MILES OR ABOVE. WITH APPROACHING WEAK FRONTAL SYSTEM PROGGED TO MOVE ACROSS THE AREA TODAY AND TONIGHT... EXPECT MVFR/VFR CEILINGS TO CONTINUE ACROSS THE AREA THROUGH THE EVENING HOURS. ONSHORE FLOW WILL PRODUCE STANDARD ONSHORE WINDS THROUGH THIS AFTERNOON...WITH SOME NORTHWEST/NORTH EXPECTED TONIGHT BEHIND THE FRONT. THESE WINDS COULD CAUSE SOME WIND SHEAR PROBLEMS ESPECIALLY OVER KSBA. AS FOR ACTUAL PRECIP...CHANCES ARE RATHER LOW...20-30% THROUGH TONIGHT. SO...WILL NOT HIT PRECIP THAT HARD IN THE 12Z TAFS. FOR KLAX...EXPECT CEILINGS AROUND 3500 FT THROUGH THE AFTERNOON WITH A SLIGHT CHANCE OF SHOWERS IN THE AFTERNOON. LIGHT WINDS THIS MORNING WILL GIVE WAY TO A SOUTHWEST WINDS 10-15 KTS THIS AFTERNOON AND EVENING. FOR KBUR...EXPECT CEILINGS AROUND 2500 FT THIS MORNING...RISING TO AROUND 3500 FT THIS AFTERNOON AND EVENING WITH A SLIGHT CHANCE OF SHOWERS. A 6-10 KT SOUTHERLY SEA BREEZE IS EXPECTED THIS AFTERNOON. DEVELOPING NORTHERLY FLOW BEHIND FRONT COULD PRODUCE SOME WIND SHEAR PROBLEMS WHICH FUTURE SHIFTS WILL HAVE TO MONITOR. && .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...RORKE AVIATION...THOMPSON WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
416 AM CDT TUE MAR 20 2007 .DISCUSSION... WATER VAPOR SATELLITE LOOPS SHOW A SHORTWAVE SOUTHWEST OF ABILENE AS OF 08Z...MOVING EAST NORTHEAST ACROSS TEXAS. THE 00Z FWD SOUNDING INDICATED THAT WE HAVE A STRONG CAPPING INVERSION... HOWEVER...THE RUC AND NAM FORECAST SOUNDINGS INDICATE THE CAP IS GOING TO WEAKEN. ACARS DATA INDICATES THAT THIS MAY BE HAPPENING. SO FAR RADAR SHOWS SOME ELEVATED REFLECTIVITY RETURNS ACROSS THE WESTERN ZONES BUT HAVE NOT HAD ANY SURFACE REPORTS OF RAIN. HAVE PLACED 20 PERCENT POPS BACK IN THE FORECAST FOR THE NORTHWESTERN TWO-THIRDS OF THE FORECAST AREAS FOR TODAY. WE WILL START OFF PRETTY WARM THIS MORNING WITH LOWS IN THE LOWER TO MID 60S...ONLY A CATEGORY BELOW THE NORMAL HIGHS. WITH CONSIDERABLE CLOUD COVER...THE DIURNAL TEMPERATURE RANGE WILL ONLY BE 10 TO 15 DEGREES. A LARGE UPPER LEVEL TROUGH WILL MOVE INTO THE WEST COAST DURING THE NEXT 24 HOURS. A LOW WILL THEN CUT OFF OVER CALIFORNIA WEDNESDAY...AND THEN DIG SOUTHWARD INTO BAJA CALIFORNIA BY THURSDAY. THE LOW WILL LIFT NORTHEAST INTO NEW MEXICO BY FRIDAY NIGHT...AND THEN INTO THE CENTRAL PLAINS OVER THE WEEKEND. WE WILL SEE AT LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WEDNESDAY AND THURSDAY...WITH THE BEST CHANCES ACROSS THE WEST. RAIN CHANCES WILL IMPROVE AREAWIDE FRIDAY THROUGH THE WEEKEND. #58 THE BEST CHANCE OF RAIN DURING THE NEXT FEW DAYS WILL BE TO THE NORTH AND && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 75 63 75 63 76 / 20 10 20 20 20 WACO, TX 76 63 75 63 76 / 20 10 20 20 20 PARIS, TX 73 62 75 61 74 / 20 10 20 20 20 DENTON, TX 75 62 75 63 74 / 20 10 20 20 20 MCKINNEY, TX 73 62 74 62 73 / 20 10 20 20 20 DALLAS, TX 75 64 75 63 76 / 20 10 20 20 20 TERRELL, TX 74 63 75 62 75 / 20 10 20 20 20 CORSICANA, TX 75 62 75 62 75 / 20 10 20 20 20 TEMPLE, TX 75 62 75 63 76 / 10 10 20 20 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 92/58
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
430 AM PDT TUE MAR 20 2007 .SYNOPSIS... A DEEP MARINE LAYER AND ONSHORE FLOW WILL CAUSE LOW CLOUDS...LOCAL FOG AND DRIZZLE WEST OF THE MOUNTAINS THIS MORNING. UPPER LEVEL LOW PRESSURE WILL BRING VARIABLE CLOUDINESS AND SMALL CHANCES OF MAINLY LIGHT PRECIPITATION AT TIMES THROUGH FRIDAY. THERE MAY ALSO MAY BE A PERIOD OF MODERATE OFFSHORE FLOW WEDNESDAY NIGHT AND THURSDAY. FAIR AND A LITTLE WARMER NEXT WEEKEND UNDER WEAK HIGH PRESSURE. SPRING BEGINS TODAY AT 507 PM PDT. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (TODAY THROUGH THURSDAY)... A TROUGH OF LOW PRESSURE WILL MOVE INLAND ALONG THE CENTRAL CALIFORNIA COAST TODAY. THOUGH NOT IN PERFECT AGREEMENT...MODELS THEN GENERALLY TAKE THIS UPPER TROUGH AND DEVELOP A CLOSED UPPER LOW THAT DRIFTS SLOWLY SOUTHWARD OFF THE SOUTHERN CALIFORNIA AND NORTHERN BAJA COASTS TONIGHT THROUGH THURSDAY. FOR THIS MORNING...A DEEP MARINE LAYER CONTINUES WEST OF THE MOUNTAINS WITH A RECENT ACARS SOUNDING FROM ONT SHOWING THE DEPTH NOW GREATER THAN 5000 FEET. PATCHY DRIZZLE IS POSSIBLE ALONG THE WEST OF THE MOUNTAINS THIS MORNING FROM THIS DEEP MARINE LAYER. SATELLITE IMAGERY ALSO SHOWS A SHORTWAVE TO THE SOUTHWEST ENHANCING MID LEVEL CLOUDINESS OFF THE SOUTHWEST CALIFORNIA AND NORTHERN BAJA COAST. THIS COULD BRING SOME LIGHT PRECIPITATION TO SOUTHWEST CALIFORNIA AT TIMES TODAY...MAINLY ALONG AND WEST OF THE MOUNTAINS. AS THIS LOW CLOSES OFF...THE CHANCE OF MAINLY LIGHT PRECIPITATION WILL CONTINUE ALONG AND WEST OF THE MOUNTAINS THROUGH WEDNESDAY MORNING. DEPENDING UPON THE TRACK AND POSITION OF THE UPPER LOW...THERE COULD BE A PERIOD OF MODERATE OFFSHORE LATE WEDNESDAY NIGHT THROUGH THURSDAY. PRECIPITATION CHANCES MAY DECREASE SOME WEDNESDAY NIGHT THROUGH EARLY THURSDAY...BUT REMAIN DEPENDENT ON THE TRACK OF THE UPPER LOW. && .LONG TERM (FRIDAY THROUGH MONDAY)... FOR THURSDAY NIGHT AND FRIDAY...MODELS CONTINUE TO SHOW SOME POTENTIAL FOR MORE SIGNIFICANT "WRAP AROUND" PRECIPITATION TO SPREAD INTO FAR SOUTHERN SECTIONS OF SOUTHERN CALIFORNIA AS THE UPPER LOW MOVES INLAND ACROSS NORTHERN AND CENTRAL BAJA. WILL CONTINUE SLIGHT CHANCE AND CHANCE POPS WITH HIGHEST POPS SOUTH. FOR THE WEEKEND...WEAK HIGH PRESSURE WILL BRING FAIR AND A LITTLE WARMER WEATHER WITH GREATEST WARMING INLAND. FOR EARLY NEXT WEEK...A STRONGER TROUGH OF LOW PRESSURE MOVING INLAND ALONG THE CALIFORNIA COAST SHOULD BRING COOLING...STRONG GUSTY WINDS IN THE MOUNTAINS AND DESERTS...AND ANOTHER CHANCE OF PRECIPITATION. SOME MODEL SPREAD IN THE TIMING AND INTENSITY...BUT GENERALLY CENTERED ON TUESDAY FOR THE MAIN IMPACT ON SOUTHWEST CALIFORNIA. && .AVIATION... 201120Z...THICK LOW OVERCAST STRATUS WILL CONTINUE TO COVER ALL AREAS WEST OF THE MOUNTAINS THROUGH 20Z WITH BASE AROUND 2500 FT MSL AND TOPS NEAR 4000 FEET. SPOTTY DRIZZLE POSSIBLE. INCREASED ONSHORE FLOW AHEAD OF AN UPPER LEVEL TROUGH WILL BRING INCREASING WEST WINDS THIS AFTERNOON. MOIST FLOW ALOFT WILL CAUSE INCREASING 10K FT ALTOSTRATUS THROUGH THE DAY. A BROKEN LAYER OF 4000 FT STRATOCU WITH ISOLATED TO SCATTERED LIGHT SHOWERS WILL COVER THE AREA LATE THIS AFTERNOON THROUGH WEDNESDAY AS A WEAK TROUGH SETTLES OVER SOUTHERN CALIFORNIA. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...MARTIN AVIATION/MARINE...MACKECHNIE NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
645 AM CDT TUE MAR 20 2007 .DISCUSSION REGARDING MORNING ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERNS WILL BE ON TEMPERATURES AND PERIODIC CHANCES OF SHOWERS/TSTORMS FROM TONIGHT THROUGH THURSDAY...AND THEN AGAIN FOR THE LATTER PART OF THE WEEKEND. SFC ANTICYCLONE CENTERED ACROSS SOUTHERN ONTARIO THIS MORNING WILL CONTINUE TO TRACK OFF TO THE EAST TODAY ALLOWING FOR WINDS TO CONTINUE TO VEER MORE EASTERLY THIS AFTERNOON. EASTERLY FLOW...WEAK LOW LEVEL THERMAL ADVECTION...AND FAIRLY LOW BASED SUBSIDENCE INVERSION WILL ALLOW FOR COOLER CONDITIONS TODAY. MIXING MODEL 950 HPA TEMPS TO THE SURFACE YIELDS HIGHS FROM UPPER 40S NORTH TO LOWER 50S SOUTH. GIVEN FULL SUN TODAY...MAY SEE TEMPS EVEN A LITTLE WARMER THAN THIS. MID LEVEL WARM ADVECTION CLOUDINESS ACROSS EASTERN DAKOTAS/WESTERN MINNESOTA SHOULD TRACK MAINLY ACROSS NORTHERN WISCONSIN TODAY WHILE LOW CLOUDS FROM THE CENTRAL PLAINS AND LOWER MS RIVER VALLEY ONLY SLOWLY NUDGE NORTHWARD TODAY. ANOTHER STRONG LOW LEVEL JET TONIGHT WILL ALLOW FOR NORTHWARD SURGE TO LOW LEVEL WARM FRONT CURRENTLY ACROSS THE SOUTHERN PLAINS WHERE SFC DEW PTS ARE IN THE UPPER 50S TO LOWER 60S. AN UPPER LEVEL SHORT WAVE ALSO EVIDENT ON WATER VAPOR IMAGERY EARLY THIS MORNING ACROSS THE TEXAS PANHANDLE WILL ALSO TRACK NORTHEAST INTO CENTRAL ILLINOIS BY LATER TONIGHT. ALTHOUGH SOME DISCREPANCIES HAVE EXISTED FROM PREVIOUS MODEL RUNS IN REGARDING TO EXACT TRACK OF THIS VORT MAX...THERE HAS BEEN GENERALLY SOME GOOD RUN TO RUN CONTINUITY WITH THIS FEATURE. STRONG POSITIVE LOW LEVEL THETA-E/MOISTURE ADVECTION WITH THIS LOW LEVEL JET WILL TAKE 850 HPA DEW PTS BACK INTO THE +7 TO +10 DEG CELSIUS RANGE AFTER 06Z WITH PWATS INCREASING TO AROUND 1.25 INCHES OVERNIGHT. MID LEVEL LAPSE RATES/ELEVATED INSTABILITY DO NOT LOOK OVERLY IMPRESSIVE TONIGHT. TAKING A PARCEL BASED FROM 900 HPA IN GFS/WRF FORECAST SOUNDINGS ONLY YIELDS 50-100 J/KG OF ELEVATED INSTABILITY. HOWEVER GIVEN STRENGTH OF LOW LEVEL THETA-E ADVECTION/ISENTROPIC LIFT WILL CONTINUE TO MENTION THUNDER. CURRENT TIMING OF SHOWERS AND THUNDERSTORMS OVERSPREADING THE AREA STILL LOOKS GOOD...POSSIBLY BY LATE IN THE EVENING IN THE FAR SOUTHWEST...AND AFTER MIDNIGHT ACROSS THE REMAINDER OF THE FORECAST AREA. MIN TEMPS TONIGHT WILL BE REACHED IN THE EVENING...WITH SLOWLY RISING TEMPERATURES OVERNIGHT. SHOWERS/STORMS WILL LIKELY EXIT THE AREA BY MIDDAY WEDNESDAY BUT WILL MAINTAIN LOWER CHANCE POPS FOR TSRA WEDNESDAY AFTERNOON WITH CWA ESTABLISHED IN WARM SECTOR. THE PRIMARY INSTABILITY AXIS WILL REMAIN OFF TO THE WEST THROUGH THE DAY WEDNESDAY AS NORTHERN STREAM WAVE TRACKS THROUGH THE GREAT BASIN AND SOUTHERN STREAM UPPER LOW GETS CUT OFF JUST OFF THE SOUTHERN CALIFORNIA COAST. DID NOTCH TEMPS UP A BIT FOR WEDNESDAY...WITH HIGHS GENERALLY IN THE MID TO UPPER 60S AND SFC DEW PTS WELL INTO THE 50S. SHOWERS AND THUNDERSTORMS EXPECTED AGAIN LATE WEDNESDAY NIGHT INTO THURSDAY AS FRONTAL BOUNDARY ASSOCIATED WITH AFOREMENTIONED NORTHERN STREAM VORT APPROACHES WESTERN PORTIONS OF THE FORECAST AREA BY THURSDAY MORNING. MOST IMPRESSIVE INSTABILITY THROUGH THE FORECAST PERIOD WILL BE LATE WEDNESDAY NIGHT INTO THURSDAY JUST AHEAD OF THIS FRONTAL BOUNDARY. UPPER SUPPORT ALSO BECOMES STRONGER WITH MODELS INDICATING 120 KT UPPER SPEED MAX CUTTING THROUGH THE WESTERN LAKES WITH LOT CWA IN A FAVORABLE PROXIMITY TO RIGHT ENTRANCE REGION OF THIS JET. DID CONTEMPLATE ISSUING FLOOD WATCH FOR THESE TWO PERIODS OF ENHANCED PRECIP...BUT CONFIDENCE IN TRYING TO PEG AREAS OF BEST RAINFALL ON THURSDAY SEEMS A BIT TRICKY AT THIS TIME. OVERNIGHT CONVECTION MAY TEND TO WEAKEN THURSDAY MORNING ACROSS NORTHWEST/NORTH CENTRAL ILLINOIS AND INTENSIFY AGAIN THURSDAY AFTERNOON ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA. WILL NEED TO MONITOR THE SITUATION HOWEVER WITH SOME HIGH WATER LEVELS ON AREA RIVERS. NO CHANGES TO THE EXTENDED PORTION OF THE FORECAST...GFS INDICATING NORTHWARD RETURN OF WARM FRONT LATE SATURDAY BUT OTHER MEDIUM RANGE MODELS SUPPORT SLOWER EVOLUTION OF INGESTING SOUTHWEST CONUS UPPER LOW SO HAVE SIDED WITH CONSENSUS AND KEPT MOST OF CWA DRY SATURDAY...WITH RETURN OF CHANCE POPS FOR TSRA ON SUNDAY. MARSILI && .AVIATION... 645 AM CDT SFC HIGH PRESSURE CONTINUES TO BUILD SOUTHEAST ACROSS ONTARIO THIS MORNING...PRODUCING COOL NORTHEASTERLY LLVL FLOW INTO FORECAST AREA. SOME MVFR STRATOCU DVLPG OFF OF LAKE MICHIGAN LAST COUPLE OF HOURS...IN SHALLOW MIXED LAYER BENEATH SIGNIFICANT SUBSIDENCE INVERSION SEEN JUST BELOW 900 HPA IN ACARS SOUNDINGS OUT OF KORD. FCST SOUNDINGS SUGGEST THIS TO BE A FAIRLY SHORT LIVED NUISANCE THIS MORNING...AS INVERSION LOWERS A BIT MORE. HOWEVER...WILL HAVE TO CARRY A FEW HOURS OF SCT/TEMPO BROKEN MVFR FOR KORD/KMDW AND KDPA. SOME GUSTINESS TO NORTHEAST WINDS EARLY THIS MORNING TOO...WITH COMBINATION OF LLVL CAA...SFC PRESSURE RISE MAXIMA AND TIGHTER PRES GRADIENT ON SOUTHERN PERIPHERY OF ANTICYCLONE. WIND EXPECTED TO SHIFT MORE EASTERLY WITH TIME DURG THE DAY...WITH GUSTS SUBSIDING BY LATE MORNING AS GRADIENT RELAXES AND SUBSIDENCE INVERSION LIMITS MIXING DEPTH. GRADIENT WINDS BECOME SOUTHEAST THIS EVENING IN 10-15 KT RANGE. NEXT CONCERN PRESENTS ITSELF TONIGHT...AS S/WV TROF LIFTS FROM SOUTHERN PLAINS AND INDUCES LLVL MOIST/WARM ADVECTION OVER BAROCLINIC ZONE TO OUR SOUTH. FROM TIMING PERSPECTIVE...APPRCHG S/WV AND MOISTURE CONVERGENCE ON 40-50 KT LLVL JET FOCUS BEST FORCING INTO FCST AREA TOWARD 12Z AS WARM FRONT LIFTS TOWARD NRN IL/NWRN IND. FCST SOUNDINGS DO NOT INDICATE SIGNIFICANT ELEVATED INSTABILITY...WITH BUFKIT ANALYSIS OF BOTH WRF/GFS SOUNDINGS DEPICTING LESS THAN 100 J/KG STARTING AT AROUND 900 HPA. THUS ATTM FEEL POINT PROB FOR THUNDER AT ANY GIVEN TERMINAL LOCATION IS PRETTY LOW...THOUGH DO SUSPECT SOME ISOLATED THUNDER ACROSS THE FCST AREA. THUS WILL NOT INCLUDE THUNDER RIGHT NOW...THOUGH WILL INDICATE CB CLOUD TYPES AFTER 08Z OR SO WITH TEMPO SHOWERS. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVSRY THROUGH NOON ALL NEARSHORE ZONES. && $$
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
932 AM CDT TUE MAR 20 2007 .DISCUSSION... 12Z CRP/LCH SOUNDINGS SHOW A MOIST LAYER IN THE LOW LEVELS TRAPPED BETWEEN A SIGNIFICANT CAP IN THE 700-800 MB LAYER. ACARS SOUDINGS SHOW WEAKER CAPPING IN THE LOW LEVELS. CRP SOUDING SHOWED A PW OF 1.31 INCHES. WATER VAPOR IMAGERY SHOWS A WEAK SHORTWAVE NEAR THE RIO GRANDE WHICH MODELS BRING ACROSS SE TX THIS EVENING. THINK WE COULD SEE SOME SPRINKLES OR A FEW LIGHT SHOWERS THIS AFTN/TONIGHT AS THIS SHORTWAVE AFFECTS THE AREA AND HAVE ADDED 20 POPS TO THE FCST. WITH INCREASED CLOUD COVER TODAY...TEMPS SHOULD BE A COUPLE OF DEGREES COOLER THAN YESTERDAY. NO SIGNIFICANT CHANGES TO THE REST OF THE FORECAST. && .PREV DISCUSSION... /ISSUED 309 AM CDT TUE MAR 20 2007/ DISCUSSION...SATELLITE IMAGES AND NAM40 500MB HEIGHT ANALYSIS INDICATED ANOTHER WEAK SHORTWAVE TROUGH MOVING ACROSS CENTRAL TEXAS THIS MORNING. RADAR IMAGES INDICATE NO CONVECTION WITH THIS FEATURE AND WITH MOISTURE CONFINED TO BELOW 850MB...RAIN CHANCES APPEAR LIMITED WITH AN INVERSION AT 850MB KEEPING A CAP ON SHOWERS DEVELOPING TODAY. THE MODELS ARE FAIRLY CONSISTENT WITH THESE WEAK SHORTWAVE TROUGHS MOVING ACROSS THE STATE THE NEXT COUPLE OF DAYS AS A TROUGH DEVELOPS ACROSS THE WESTERN UNITED STATES TODAY. THE 500MB TROUGH ACROSS THE WESTERN U.S. IS PROGGED TO CUT OFF AS A LOW ACROSS SOUTHERN CALIFORNIA/NORTHERN BAJA CALIFORNIA WEDNESDAY AND DRIFT SOUTHWARD THURSDAY. THIS WILL ALLOW A SHORTWAVE RIDGE TO DEVELOP ACROSS SOUTH TX WEDNESDAY AND PERSIST ACROSS EAST TX THURSDAY. THIS FEATURE SHOULD KEEP MOST OF THE CONVECTION WELL TO THE NORTH AND WEST OF THE CWA THROUGH THE REST OF THE WEEK. AS THE 500MB LOW ACROSS NORTHWEST MEXICO FRIDAY BEGINS TO MOVE NORTHEASTWARD SATURDAY...THE 500MB RIDGE ACROSS THE GULF OF MEXICO WILL WEAKEN ACROSS EAST TX ALLOWING LOW TO MID LEVEL MOISTURE TO INCREASE AND PROVIDE A CHANCE OF SHOWERS AND THUNDERSTORMS FOR SOUTHEAST TX THIS WEEKEND...AS THE 500MB LOW OPENS UP AND EJECTS INTO THE CENTRAL AND SOUTHERN PLAINS AS A TROUGH. WILL GO AHEAD AND INCREASE POPS SLIGHTLY SATURDAY AND SUNDAY BUT REMOVE MENTION OF RAIN CHANCES INTO EARLY NEXT WEEK AS THE SOUTHWESTERLY FLOW ALOFT VEERS TO THE NORTHWEST SUN NIGHT WITH THE TROUGH MOVING ACROSS THE MIDDLE AND LOWER MISSISSIPPI RIVER VALLEY. 32 AVIATION... MVFR CIGS THIS MORNING SHOULD GRADUALLY LIFT INTO THE VFR CATEGORY BY LATE MORNING. PLAN ON BUMPING SE WINDS UP TO AROUND 15KT DURING THE AFTERNOON HOURS FOR MOST TERMINALS. PROBABLY SEE A REPEAT OF MVFR CIGS DEVELOPING OVERNIGHT...BUT WINDS SHOULD AGAIN KEEP THEM FROM GOING TOO LOW. 47 MARINE... MODERATE E & SE FETCH BECOMING WELL ESTABLISHED ACROSS THE ENTIRE GULF WITH HIGH PRESSURE ANCHORED OFF THE EAST COAST AND LOWER PRESSURES SITUATED ACROSS THE PLAINS. THIS SAME SCENARIO SHOULD PERSIST INTO THE WEEKEND. WILL KEEP THE CAUTION FLAGS FLYING IN THE 20-60NM GROUP TODAY (AND WILL LIKELY BE NEEDED MOST OF THE WEEK). MAY SEE SOME PERIODS WHERE FLAGS MAY NEED TO BE EXPANDED INTO THE NEARSHORE GROUP AND/OR ADVSY CRITERIA MAY BE MET OFFSHORE...WHICH TYPICALLY HAPPENS IN THE NIGHTTIME PERIODS THIS TIME OF YEAR WHEN WINDS ARE SLIGHTLY HIGHER. NO FRONTS IN SIGHT FOR THE NEXT 10+ DAYS. 47 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 76 64 78 64 76 / 20 20 10 10 10 HOUSTON (IAH) 77 64 77 64 77 / 20 20 10 10 10 GALVESTON (GLS) 75 65 76 65 73 / 20 20 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH WEDNESDAY MORNING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...35
AREA FORECAST DISCUSSION...UPDATED FOR AVIATION
NWS FORT WORTH TX
630 AM CDT TUE MAR 20 2007 .AVIATION... MAIN CONCERN IS CIGS DURING THE NEXT FEW HOURS. A WAVE OF INTENSE MOISTURE ADVECTION IS NOW REACHING THE METROPLEX AND IS RESULTING IN MVFR VIS WITH DRIZZLE AND CIGS NEAR 800 FEET. WILL SHOW IFR CIGS IN A TEMPO GROUP THROUGH 14Z...THINKING THAT THEY WILL LIFT BACK TO MVFR FOR THE REMAINDER OF THE MORNING ONCE THE DRIZZLE MOVES ON THROUGH. SOME ELEVATED SHOWERS WILL ALSO BE POSSIBLE AS SHORTWAVE MOVES THROUGH THIS MORNING. WILL LEAVE THUNDER OUT OF TAF AND OPT FOR JUST VCSH. OTHERWISE...THE MVFR CIGS WILL LIFT TO VFR IN SIMILAR FASHION AS SEEN YESTERDAY AROUND MID AFTERNOON BEFORE COMING DOWN TO MVFR AFTER MIDNIGHT TONIGHT. SOUTH WINDS OF 15 TO 20 KNOTS WILL CONTINUE THROUGH THE PERIOD. TR.92 && .DISCUSSION... WATER VAPOR SATELLITE LOOPS SHOW A SHORTWAVE SOUTHWEST OF ABILENE AS OF 08Z...MOVING EAST NORTHEAST ACROSS TEXAS. THE 00Z FWD SOUNDING INDICATED THAT WE HAVE A STRONG CAPPING INVERSION... HOWEVER...THE RUC AND NAM FORECAST SOUNDINGS INDICATE THE CAP IS GOING TO WEAKEN. ACARS DATA INDICATES THAT THIS MAY BE HAPPENING. SO FAR RADAR SHOWS SOME ELEVATED REFLECTIVITY RETURNS ACROSS THE WESTERN ZONES BUT HAVE NOT HAD ANY SURFACE REPORTS OF RAIN. HAVE PLACED 20 PERCENT POPS BACK IN THE FORECAST FOR THE NORTHWESTERN TWO-THIRDS OF THE FORECAST AREAS FOR TODAY. WE WILL START OFF PRETTY WARM THIS MORNING WITH LOWS IN THE LOWER TO MID 60S...ONLY A CATEGORY BELOW THE NORMAL HIGHS. WITH CONSIDERABLE CLOUD COVER...THE DIURNAL TEMPERATURE RANGE WILL ONLY BE 10 TO 15 DEGREES. A LARGE UPPER LEVEL TROUGH WILL MOVE INTO THE WEST COAST DURING THE NEXT 24 HOURS. A LOW WILL THEN CUT OFF OVER CALIFORNIA WEDNESDAY...AND THEN DIG SOUTHWARD INTO BAJA CALIFORNIA BY THURSDAY. THE LOW WILL LIFT NORTHEAST INTO NEW MEXICO BY FRIDAY NIGHT...AND THEN INTO THE CENTRAL PLAINS OVER THE WEEKEND. WE WILL SEE AT LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WEDNESDAY AND THURSDAY...WITH THE BEST CHANCES ACROSS THE WEST. RAIN CHANCES WILL IMPROVE AREAWIDE FRIDAY THROUGH THE WEEKEND. #58 THE BEST CHANCE OF RAIN DURING THE NEXT FEW DAYS WILL BE TO THE NORTH AND && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 75 63 75 63 76 / 20 10 20 20 20 WACO, TX 76 63 75 63 76 / 20 10 20 20 20 PARIS, TX 73 62 75 61 74 / 20 10 20 20 20 DENTON, TX 75 62 75 63 74 / 20 10 20 20 20 MCKINNEY, TX 73 62 74 62 73 / 20 10 20 20 20 DALLAS, TX 75 64 75 63 76 / 20 10 20 20 20 TERRELL, TX 74 63 75 62 75 / 20 10 20 20 20 CORSICANA, TX 75 62 75 62 75 / 20 10 20 20 20 TEMPLE, TX 75 62 75 63 76 / 10 10 20 20 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 92/58