Forecast Discussions mentioning "ACARS", "MDCRS", or "AIRCRAFT" received at FSL on 03/28/02

...MAIN QUESTION THIS CYCLE WILL BE TEMPERATURES AND THUNDERSTORM POPS IN NORTHEAST ZONES FOR TONIGHT...

THE 12Z DIAGNOSTICS INDICATE A NORTHERN BRANCH BAROCLINIC ZONE FROM THE PACIFIC NORTHWEST INTO THE NORTH CENTRAL PLAINS AND OHIO VALLEY. A SOUTHERN BRANCH CLOSED UPPER LOW WAS WEST OF SOUTHERN CALIFORNIA WITH THE SOUTHERN BRANCH BAROCLINIC ZONE ACROSS NORTHERN MEXICO AND TEXAS AND EASTWARD ALONG THE GULF COAST STATES. SEVERAL SHORT WAVE TROUGHS WERE EVIDENT IN THE NORTHERN BRANCH FLOW. ONE WAS CROSSING THE NORTHERN PLAINS STATES THIS MORNING WITH ANOTHER JUST UPSTREAM MOVING INTO WESTERN MONTANA. H8 AND SURFACE ANALYSIS INDICATE A NORTHERN BRANCH FRONT NOW MOVING INTO NORTHERN UTAH AND NORTHWEST WYOMING HEADED FOR THE CENTRAL PLAINS STATES. THE SOUTHERN BRANCH POLAR FRONT HAD SURGED WILL SOUTH ACROSS THE GULF OF MEXICO AND SOME SHALLOW LOW LEVEL MOISTURE WAS RETURNING UP THE RIO GRANDE VALLEY NORTH OF THE FRONT AS SEEN ON THE SOUNDINGS IN THAT AREA. JET LEVEL ANALYSIS SHOWED 160KTS AT H25 MOVING INTO THE PACIFIC NORTHWEST REGION WHILE UPPER FLOW AROUND THE CLOSED LOW IN THE SOUTHERN BRANCH WAS FAIRLY WELL BALANCED SO THAT THE SOUTHERN BRANCH APPEARS MUCH LESS ACTIVE THAN THE NORTHERN BRANCH. AT THE SURFACE OVER THE HIGH PLAINS A DEVELOPING LEE WARM TROUGH OVER EAST COLORADO HAD PRODUCED STRONG SOUTHWESTERLY SURFACE FLOW ACROSS WEST KANSAS AS THE SURFACE HIGH OVER THE MISSISSIPPI VALLEY CONTINUES ITS EASTERLY TREK.

MODEL INITIALIZATIONS LOOK QUITE REASONABLE THIS MORNING, EVEN OVER THE EAST PACIFIC WHERE SUBSTANTIAL AMOUNTS OF AIREP AND ACARS DATA APPEARS TO HAVE NICELY SAMPLED THE MAIN FEATURES. GIVEN THIS, WILL EXPECT THE MODELS TO DO WELL WITH THE SYNOPTIC SCALE MASS FIELDS WITH THE NGM BEING LEAST HELPFUL AS IT MOVES THE SYSTEMS TOO FAST AND TOO FAR NORTH WITH TIME. MODEL MOISTURE FIELDS ARE A BIT MORE DIFFICULT TO VALIDATE AS THERE REALLY IS LITTLE IN THE WAY OF MOISTURE IN EITHER OF THE BAROCLINIC ZONES TO WORK WITH. WITH TIME THE MODEL FORECASTS ARE VERY SIMILAR IN THEIR HANDLING OF THE LIMITED MOISTURE AVAILABLE AND AM INCLINED TO TRUST THEM IN KEEPING ANY SIGNIFICANT MID OR LOWER TROPOSPHERIC MOISTURE WELL OUT OF MY FORECAST AREA.

THE FORECAST SCENARIO THEN WILL CALL FOR THE DEEPENING LEE LOW OVER COLORADO TODAY TO BE SHUNTED SOUTHEAST INTO OKLAHOMA TONIGHT AS THE NORTHERN BRANCH FRONT SURGES ACROSS KANSAS. HIGHER LEVEL CLOUD IS CURRENTLY EVIDENT IN THE IR IMAGERY WITH THE SHORT WAVE DRIVING THIS SYSTEM BUT NOT A LOT OF IT THUS WILL STICK WITH THE PARTLY CLOUDY WORDING FOR TONIGHT. WITH LITTLE AVAILABLE MOISTURE AND SOMEWHAT LIMITED INSTABILITY TONIGHT WILL OPT TO REMOVE THE SMALL POPS IN MY NORTHEAST ZONES. BRISK SOUTH TO SOUTHWEST FLOW TODAY AHEAD OF THE SURFACE LOW WILL TAPER OFF FROM WEST TO EAST THIS EVENING AS THE SURFACE LOW MOVES FROM SOUTHEAST COLORADO INTO THE OKLAHOMA PANHANDLE BY MIDNIGHT. THEREAFTER, STRONG NORTHWEST WINDS SHOULD DEVELOP TOWARD MORNING AS THE SURFACE FRONT MOVES THROUGH. THE WIND SHOULD QUICKLY DIMINISH TOMORROW MORNING HOWEVER AS THE LOW MOVES OUT AND IS REPLACED BY A SURFACE HIGH OVER KANSAS.

THE SOUTHERN BRANCH CLOSED UPPER LOW SHOULD MAKE LANDFALL IN WESTERN MEXICO DURING THE DAY THURSDAY WITH THE SOUTHERN BRANCH BAROCLINIC ZONE INDUCING LEE TROUGHING FROM SOUTHEAST COLORADO INTO THE TEXAS BIG BEND AREA. THROUGH THE FORECAST, RETURN MOISTURE FROM THE GULF REMAINS CUT OFF BY THE SOUTHERN BAROCLINIC ZONE THOUGH DEVELOPING LOW PRESSURE OVER WEST TEXAS MAY DRAW A LITTLE CLOUD INTO MY SOUTHERN ZONES BY FRIDAY AFTERNOON AS IT WRAPS AROUND THE NORTHEAST QUADRANT OF THE LOW.

FOR TEMPERATURES, THE MOS LOOKS QUITE GOOD THOUGH A BIT TOO WARM ON FRIDAY. IN SHORT. NOT MUCH CHANGE FROM THE GOING FORECAST.

DAYS 3-7... WATER VAPOR SHOWS THE SOUTHERN STREAM SYSTEM MOVING EAST ALONG 26N. A MORE SOUTHERN SOLUTION STILL SEEMS REASONABLE. THE SOUTHERN EDGE OF THE NORTHERN STREAM WESTERLIES WILL LIE ACROSS KANSAS AND NEBRASKA THIS WEEKEND, SUPPRESSING THE NORTHERN EXTENT OF THE PRECIP TO THE SOUTH. THUS A DRY FCST SEEMS APPROPRIATE THROUGH THE EXTENDED. A STRONG NORTHERN STREAM SHORTWAVE TROUGH IS EXPECTED INTO THE PLAINS MONDAY AND TUESDAY, PUSHING A COLD FRONT ACROSS KANSAS. AN EVEN STRONGER NORTHERN STREAM SYSTEM MAY AFFECT THE PLAINS AFTER DAY 7. THERE IS STILL PLENTY OF COLD AIR ACROSS CANADA, SO ANOTHER COLD SURGE IS POSSIBLE BY LATE NEXT WEEK.

PRELIMINARY GUIDANCE FOR COORDINATION ONLY. OFFICIAL FORECASTS ARE CONTAINED WITHIN THE DODGE CITY ZONE FORECAST.

DDC 40 65 38 62 / 0 0 0 0 GCK 38 68 35 65 / 0 0 0 0 EHA 40 73 37 66 / 0 0 0 0 LBL 41 72 39 66 / 0 0 0 0 HYS 39 63 37 65 / 0 0 0 0 P28 45 68 42 66 / 0 0 0 0

.DDC...NONE.

JOHNSON/FINCH



ONLY MINOR CONCERN WITH THIS FORECAST PACKAGE WILL BE WIND SPEEDS AND TEMPERATURES THIS AFTERNOON.

LATEST LOOK AT THE VIS IMAGERY SHOWS VERY LITTLE IF ANY CLOUDS ACROSS THE CWFA THIS MORNING. ON THE HORIZON...THERE ARE SOME HIGH CLOUDS SCOOTING ACROSS WYOMING THIS MORNING...BUT THEY SHOULD NOT AFFECT CWFA UNTIL TONIGHT. IN THE MEANTIME...TEMPERATURES SHOULD RESPOND VERY NICELY THIS AFTERNOON DUE TO GOOD MIXING AND NICE WARM ADVECTION TAKING PLACE IN THE LOW LEVELS. LATEST ACARS SOUNDING FROM ICT DISPLAYED WINDS BETWEEN 20 AND 30KTS IN THE MIXING LAYER THIS MORNING. AS A RESULT...WE ARE GOING TO BUMP UP WIND SPEEDS THIS AFTERNOON TO 20 TO 30 MPH IN CENTRAL KS. LATEST UPPER AIR PLOTS SHOWS 850 TEMPS AROUND +12 DEG C AT DDC. MODELS PROG THIS WARM POCKET TO SHIFT EAST TO CENTRAL KANSAS LATE THIS AFTERNOON. AS A RESULT...WE BUMPED TEMPS UP ONE CATEGORY IN ALL LOCATIONS.

ISC GRIDS HAVE BEEN SENT.

.ICT...NONE

COX



SYNOPSIS...SCATTERED SHOWERS WILL DEVELOP OVER PARTS OF THE MOJAVE DESERT THURSDAY AS AN AREA OF LOW PRESSURE MOVES ONSHORE NEAR SAN DIEGO. SKIES WILL CLEAR AGAIN FRIDAY AS THE DISTURBANCE MOVES ACROSS SOUTHERN ARIZONA. HIGH PRESSURE WILL BRING WARMER TEMPERATURES OVER THE UPCOMING EASTER WEEKEND.

DISCUSSION...THE ETA SOLUTION HAD A SLIGHTLY BETTER FIT TO THE OFFSHORE UPPER LOW POSITION THROUGH 22Z BASED ON WATER VAPOR IMAGERY AND AIRCRAFT REPORTS. BOTH MODELS INDICATE STRONG MID-LEVEL FORCING AND STEEP LAPSE RATES OVER THE HIGH DESERTS AHEAD OF THE LOW BUT THE AVN IS DEEPER AND FARTHER NORTH WITH THE TRAJECTORY OF THE STORM. IF THE AVN IS CORRECT A THREAT OF SHOWERS COULD EXTEND AS FAR NORTH AS THE SPRING MOUNTAINS AND LAS VEGAS VALLEY...WHEREAS THE ETA CONFINES THE BEST FORCING FARTHER SOUTH...CLOSER TO THE MID-LEVEL COLD POOL. PW IS FORECAST TO BE RATHER MEAGER BUT MODEST INSTABILITY AND SOME MOISTENING FROM VERTICAL MOTION SHOULD SUPPORT SCATTERED SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS THURSDAY AFTERNOON AND EVENING FROM SAN BERNARDINO COUNTY CA ACROSS SOUTHERN MOHAVE COUNTY AZ. LINGERING CLOUDS AND SHOWERS SHOULD PERSIST INTO FRIDAY MORNING UNDER AN AXIS OF STRETCHING DEFORMATION AROUND THE NORTHERN PERIPHERY OF THE LOW. RAPID CLEARING IS EXPECTED BY FRIDAY AFTERNOON AS THE CIRCULATION ACCELERATES EASTWARD ACROSS SOUTHERN ARIZONA.

ALL MODELS CONSISTENT IN DEVELOPING A BROAD FLAT RIDGE BEHIND THE UPPER LOW WITH A DRY NORTHWEST FLOW ALOFT OVER THE REGION THROUGH SUNDAY MORNING. DURING THE EXTENDED PERIOD...BOTH THE MRF AND ECMWF CARVE OUT A NORTHERN STREAM TROUGH OVER THE GREAT BASIN MONDAY AND TUESDAY. THE MAIN IMPACT WILL BE SLIGHT COOLING AND LOCALLY BREEZY CONDITIONS EARLY NEXT WEEK.

RUNK

.LAS...NONE.



SURFACE RIDGE OVER THE UPPER TEXAS COAST THIS EVENING. SURFACE WINDS WERE ALREADY SOUTH TO SOUTHEAST...AND EXPECTING HIGHER DEWPOINTS TO ADVECT IN THROUGH THE NIGHT. FORECAST ITEMS FOR CONSIDERATION INCLUDE TEMPERATURES AND SKY COVER.

AT 500 MB WINDS WERE WESTERLY OVER SE TX. THE UPPER LOW ADVERTISED TO AFFECT THE STATE LATER THIS WEEK WAS STILL OFF THE CA COAST THIS EVENING. THE MODELS INDICATE A SHORTWAVE TROUGH MOVING OVER THE AREA TONIGHT. THE 00Z SOUNDING AT LCH WAS QUITE DRY...WHILE AT CRP A STRONG CAP WAS IN PLACE AT 750 MB. AT THE MOMENT THE ACARS AND MAPS SOUNDING FOR IAH AT 00Z SHOWED A PROFILE LIKE THE ONE AT LCH...YET FOR PSX THE PROFILE WAS APPROACHING THE ONE AT CRP. WITH THIS IN MIND FEEL THE DEWPOINTS WILL BE ON THE RISE AND THAT THE OVERNIGHT LOW TEMPERATURES MAY BE A CATEGORY HIGHER THAN EARLIER EXPECTED. THE 00Z FWC HINTS AT THIS PROSPECT. THE CLOUD COVER WILL BE ON THE INCREASE AS EARLIER FORECAST.

PL-40 36

.HGX...NONE.



LARGE EDDY TYPE CIRCULATION EVIDENT ON SAT PICS THIS EVENING. THE CYCLONIC CIRCULATION WAS INFLUENCED BY THE PROXIMITY OF AN UPPER LOW NEAR 30N/121W. MARINE LAYER DEPTH HAS INCREASED QUICKLY THIS EVENING OVER VTU/L.A. COUNTIES AND WAS NEAR 5000 FEET DEEP ACCORDING TO LATEST ACARS SOUNDINGS AT LAX AND LGB. THE MARINE LAYER DEPTH WAS MUCH SHALLOWER OVER NORTHERN PARTS OF THE DISTRICT AS THE 00Z VBG SOUNDING SHOWED A DEPTH OF ONLY AROUND 1500 FEET. MARINE LAYER CLOUDS HAVE EXPANDED RAPIDLY IN COVERAGE THIS EVENING AS WAS WELL UP TO THE COASTAL SLOPES. NO REPORTS OF DRIZZLE YET...BUT WITH SUCH A QUICKLY DEEPENING MARINE LAYER THERE SHOULD BE DRIZZLE AND LIGHT SHOWERS DEVELOPING OVER PORTIONS OF THE DISTRICT OVERNIGHT.

UPPER LOW IS FORECAST TO MOVE SLOWLY EAST INTO NORTHERN BAJA BY THU AFTERNOON...THEN FURTHER EAST INTO NEW MEXICO BY FRI AFTERNOON...AS AN UPPER RIDGE BUILDS OFF THE COAST. THE UPPER LOW WILL KEEP THE DEEP MARINE LAYER OVER THE DISTRICT THRU THU...WITH A CHANCE OF MORE LIGHT SHOWERS OVER MUCH OF THE DISTRICT FROM POINT CONCEPTION SOUTHWARD. THE MARINE LAYER WILL SHRINK SOME THU NITE BUT STILL SHOULD AFFECT MUCH OF THE DISTRICT. THE MARINE LAYER SHOULD CONTINUE TO INFLUENCE THE WEATHER ESPECIALLY OVER VTU/L.A. COUNTIES FRI...BUT MOST AREAS SHOULD HAVE PARTLY CLOUDY TO MOSTLY SUNNY SKIES FRIDAY AFTERNOON. TEMPERATURES THRU FRI WILL BE GENERALLY NEAR OR SLIGHTLY BELOW NORMAL...HOWEVER OVER SLO COUNTY AND PORTIONS OF SBA COUNTY AFTERNOON TEMPS SHOULD WARM TO ABOVE NORMAL BY FRIDAY.

FAIR AND WARMER WEATHER IS EXPECTED SATURDAY THROUGH MONDAY. AN UPPER HIGH IS EXPECTED TO PERSIST OFF THE CENTRAL AND NORTHERN CA COAST DURING THE PERIOD...WHILE A WEAK UPPER TROF UNDERCUTS THE UPPER RIDGE AND EXTENDS FROM EXTREME SOCAL OFF THE COAST OF NORTHERN BAJA. SOME LIGHT OFFSHORE FLOW NIGHT AND MORNING HOURS WILL GIVE WAY TO ONSHORE FLOW DURING THE AFTERNOON THRU THE PERIOD. THICKNESSES AND 850 MB TEMPS INCREASE DURING THE PERIOD...AND HIGH TEMPS SHOULD WARM TO ABOVE NORMAL LEVELS OVER MUCH OF THE DISTRICT BY SUN AND CONTINUE MON... ALTHOUGH TEMPS OVER THE COASTAL PLAIN SHOULD REMAIN NEAR NORMAL OR PERHAPS ONLY SLIGHT ABOVE NORMAL.

WILL UPDATE THE ZONES BY 10 PM TO ADJUST WORDING FOR THE CLOUDINESS IN THE FIRST PERIOD FOR SEVERAL ZONES...MAINLY TO REFRESH ZONES BASED ON THE RAPIDLY EXPANDING MARINE LAYER. OTHERWISE...BALANCE OF THE ZONES LOOKS GOOD.

LAX 1200. SIRARD.

.LOX...NONE.



SYNOPSIS...SCATTERED SHOWERS WILL DEVELOP OVER PARTS OF THE MOJAVE DESERT THURSDAY AS AN AREA OF LOW PRESSURE MOVES ONSHORE NEAR SAN DIEGO. SKIES WILL CLEAR AGAIN FRIDAY AS THE DISTURBANCE MOVES ACROSS SOUTHERN ARIZONA. HIGH PRESSURE WILL BRING WARMER TEMPERATURES OVER THE UPCOMING EASTER WEEKEND.

DISCUSSION...PER SATELLITE AND RAOB/AIRCRAFT DATA...THE ETA SOLUTION CONTINUES TO HAVE A BETTER FIT TO THE POSITION AND STRENGTH OF OFFSHORE UPPER LOW THROUGH 03Z. THIS WAS NOTED BY THE PREVIOUS SHIFT AND SINCE THIS TREND HAS CONTINUED...IT ADDS SOME CONFIDENCE TO THE CURRENT FORECAST. HOWEVER...IT IS WORTH NOTING THAT SOME UNCERTAINTY REMAINS ABOUT WHETHER OR NOT ANY LIGHT SHOWERS WILL DEVELOP THURSDAY NIGHT FARTHER NORTH THAN FORECAST AS THE LOW MOVES INLAND.

MODELS CONTINUE IN RELATIVELY GOOD AGREEMENT AND HAVE THE MID-LEVEL CIRCULATION TRACKING EAST THURSDAY AND MOVE IT INLAND ACROSS NORTHERN BAJA AND INTO NORTHWEST SONORA THURSDAY NIGHT. AVN CONTINUES SLIGHTLY FARTHER NORTH AND DEEPER THAN THE ETA...BUT GIVEN THE BETTER PERFORMANCE OF THE ETA WOULD TEND TO DISCOUNT THE MINOR DIFFERENCES WITH THE AVN.

BOTH MODELS INDICATE MODERATE TO STRONG MID-LEVEL FORCING AND STEEP LAPSE RATES DEVELOPING OVER THE HIGH DESERTS AHEAD OF THE LOW THURSDAY AFTERNOON. PRECIPITABLE WATER VALUES ARE FORECAST TO BE RATHER MEAGER BUT MODEST INSTABILITY AND SOME MOISTENING FROM VERTICAL MOTION SHOULD SUPPORT SCATTERED SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS THURSDAY AFTERNOON AND EVENING FROM SAN BERNARDINO COUNTY CA ACROSS SOUTHERN MOHAVE COUNTY AZ. POSSIBLE THAT EVEN EXTREME SOUTHERN CLARK COUNTY MIGHT BE ADDED TO THIS AREA AS WELL. THE THREAT FOR SHOWERS REMAINS IN THOSE SAME AREAS THURSDAY NIGHT BUT QUICKLY ENDS FRIDAY MORNING (FROM WEST TO EAST) AS THE LOW PULLS AWAY. AGAIN...BUYING OFF TOTALLY ON THE AVN WOULD MEAN INCLUDING SOUTHERN INYO COUNTY...SOUTHERN NYE COUNTY AND THE REST OF CLARK COUNTY (INCLUDING THE LAS VEGAS VALLEY) FOR THE THREAT OF PRECIPITATION THURSDAY NIGHT. ETA SUPPORTS THE CURRENT FORECAST AND GIVEN THE BETTER PERFORMANCE TODAY WILL STAND BY THIS IDEA.

NEMETH

.LAS...NONE.