Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 02/12/07

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
847 PM PST FRI FEB 9 2007 .SYNOPSIS... AN APPROACHING PACIFIC STORM SYSTEM WILL BRING AN INCREASING CHANCE OF RAIN FOR SATURDAY AFTERNOON...WITH RAIN BECOMING LIKELY OVER AND WEST OF THE MOUNTAINS LATE SATURDAY INTO SUNDAY. A SLIGHT CHANCE OF SHOWERS WILL LINGER INTO MONDAY AS THE LOW MOVES EAST. ANOTHER... COLDER LOW PRESSURE SYSTEM WILL BRING A CHANCE OF SHOWERS TUESDAY AND TUESDAY NIGHT. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES. MID AND HIGH CLOUDS CONTINUE TO STREAM IN AHEAD OF A FRONTAL SYSTEM THAT IS STILL ABOUT 900 MILES WEST OF SAN DIEGO. TIME CROSS SECTIONS OF GFS MODEL SHOW MAIN DEEP LEVEL MOISTURE TO REACH ORANGE COUNTY AFTER 2 PM SATURDAY AND AFTER 8 PM IN SAN DIEGO COUNTY. EXPECT HEAVIEST RAINFALL AFTER THESE TIMES. THE NAM MODEL IS DISTINCTLY DRIER AND SLOWER BUT STILL SHOWS A DECENT FRONTAL BAND MOVING THROUGH THE AREA BUT NOT UNTIL SUNDAY MORNING. RAINFALL FORECAST AMOUNTS SHOULD RANGE FROM ABOUT 1/4 TO 1/2 INCH W OF THE MOUNTAINS WITH 1/2 TO 1 INCH ON THE W FACING MOUNTAIN SLOPES. THERE SHOULD BE ABOUT 1/3 INCH IN THE HIGH DESERTS AND LESS THAN A 1/4 INCH IN THE LOWER DESERTS. THIS SYSTEM IS QUITE WARM SO EXPECT SNOW ONLY ON THE HIGHER MOUNTAINS OF SAN BERNARDINO AND RIVERSIDE COUNTY. SHOWERS WILL LIKELY LINGER INTO SUNDAY AFTERNOON. STRONGER WINDS ALOFT AND ONSHORE FLOW WILL CAUSE LOCAL GUSTY WINDS...MAINLY IN THE MOUNTAINS AND DESERTS SATURDAY AND SUNDAY BUT WINDS ARE EXPECTED TO REMAIN BELOW ADVISORY STRENGTH. ANOTHER SYSTEM...A LITTLE COLDER WILL BRING ANOTHER THREAT OF PRECIPITATION LATE MONDAY AND TUESDAY. THIS SYSTEM LOOKS TO BRING ABOUT THE SAME PRECIPITATION AMOUNTS. SHOWERS MAY LINGER INTO WEDNESDAY MORNING. DRIER NW FLOW ALOFT WILL DEVELOP DURING THE DAY WEDNESDAY AND CONTINUE THROUGH THURSDAY. && .AVIATION... THE 00Z NKX SOUNDING AND EARLY EVENING ACARS SOUNDINGS INDICATE THE MARINE LAYER REMAINS QUITE SHALLOW...LESS THAN 500 FEET BUT SHOULD DEEPEN UP OVERNIGHT. MID AND HIGH CLOUDS ARE OBSCURING THE LOWER LEVELS SO UNABLE TO DETERMINE THE EXTENT...IF ANY...OF STRATUS OVER THE COASTAL WATERS. HOWEVER...RECENT METAR FROM KAVX AND KNUC SUGGEST THERE IS SOME STRATUS OUT THERE. EXPECT SOME OF THIS STRATUS TO MOVE ONSHORE LATER THIS EVENING BRINGING BROKEN TO OVERCAST CONDITIONS TO THE COASTAL AIRPORTS. BASES SHOULD BE AROUND 1000 FEET MSL WITH TOPS AROUND 1500 FEET. STRATUS IS EXPECTED TO GO SCATTERED FOR A FEW HOURS SATURDAY MORNING BUT BE REPLACED LATER SATURDAY MORNING BY A STRATOCU LAYER AHEAD OF APPROACHING TROUGH OF LOW PRESSURE. ABOVE THE MARINE LAYER...VARIABLE AMOUNTS OF MID AND HIGH CLOUDS THROUGH TONIGHT...MOSTLY ABOVE 12000 FEET. CLOUDS LOWERING ON SATURDAY AS THE TROUGH APPROACHES WITH LAYERS BETWEEN 4 TO 6 THOUSAND FEET EXPECTED TO MOVE IN DURING THE MORNING. THIS WILL BE ABOVE THE LOWER STRATOCU LAYER MENTIONED ABOVE. SOME LIGHT RAIN IS EXPECTED WITH SOME VISIBILITY RESTRICTIONS OVER THE NORTHERN AREAS LATE IN THE MORNING SPREADING SOUTH AND EAST ACROSS THE AREA THROUGH THE AFTERNOON. && .SGX WATCHES/WARNINGS/ADVISORIES... HIGH SURF ADVISORY SUNDAY THROUGH MONDAY FOR THE ORANGE AND SAN DIEGO COUNTY COASTAL AREAS...SEE LAXCFWSGX. SPECIAL WEATHER STATEMENT...SEE LAXSPSSGX. && $$ PUBLIC...ECC AVIATION...HORTON
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1045 PM EST SUN FEB 11 2007 .UPDATE... UPDATE FOCUSES ON LES TRENDS. LATEST MQT RADAR LOOP SHOWS DOMINANT LES BAND WHICH FORMED ALONG WIND SHIFT LINE HAS SAGGED SE ALONG SHOT POINT-MUNISING LINE. STILL SOME REFLECTIVITIES EXCEEDING 30 DBZ WITHIN THIS NARROW BAND AND WOULD NOT BE SURPRISED IF SNOWFALL RATES ARE EXCEEDING AN INCH/HOUR AS IT PASSES. QUESTIONS FOR OVERNIGHT WILL BE WHETHER OR NOT THIS BAND WILL PERSIST IN INTENSITY OR IF ANOTHER BAND WILL REFORM OVER ERN ALGER AND NRN SCHOOLCRAFT COUNTIES IN AREA OF ENHANCED LOW-LEVEL CONVERGENCE AS DEPICTED BY 00Z MESOSCALE MODELS (RUC13, NAM12, AND WRF-ARW). GIVEN THAT THE BAND APPEARS TO BE DIMINISHING SOMEWHAT ALONG ITS WESTERN EXTENT...IT LOOKS LIKE MESOSCALE MODELS MIGHT HAVE RIGHT IDEA. SO WOULD LOOK FOR CURRENT BAND TO EITHER PROPAGATE BACK EAST OR REFORM OVER ERN ALGER AND NRN SCHOOLCRAFT LATER TONIGHT AS LAND BREEZES HELP FOCUS LOW-LEVEL CONVERGENCE OVER THIS AREA. KEPT IN ADDITIONAL AMTS OF 1-3 INCHES FOR ALGER COUNTY IN THE OVERNIGHT PERIOD. ALSO TRIMMED BACK LES COVERAGE FM NUMEROUS TO SCATTERED ALONG MQT COUNTY LAKESHORE AREA GIVEN THAT BETTER CONVERGENCE WILL TEND TO BE FOCUSED FARTHER E. OTHER CHANGE WAS TO TRIM BACK POPS OVER WRN COUNTIES AS VERY DRY AIR UPSTREAM AND ANTICYCLONIC FLOW HAVE BASICALLY DIMINISHED LES TO FLURRIES THERE AS NOTED ON IR SATELLITE IMAGERY. && .SHORT TERM (TONIGHT AND MONDAY)... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD VORTEX CENTERED IN THE VCNTY OF JAMES BAY AND A RIDGE EXTENDING FROM THE SRN ROCKIES TO THE NE GULF OF ALASKA. RESULT IS NW FLOW DOMINATING THE GREAT LAKES REGION. MAIN FEATURE OF INTEREST IN THE SHORT TERM IS A SHEARED SHORTWAVE DROPPING SE ACROSS MANITOBA/ONTARIO. AT THE LOW LEVELS... CONVERGENT WRLY FLOW OVER WRN LAKE SUPERIOR HAS LED TO MAIN ZONE OF LES ACROSS N HALF OF HOUGHTON COUNTY THIS AFTN. HOWEVER...THE GENERALLY DRY UPSTREAM AIRMASS PER 12Z KINL SOUNDING HAS LARGELY KEPT LES IN CHECK. 19Z TAMDAR SOUNDING FROM KCMX LOOKED MORE SUPPORTIVE OF DECENT LES THOUGH WITH INVERSION AT 830MB (5.4KFT)... SO THERE MIGHT BE SOME LOCALIZED HEAVIER SNOW BURSTS OCCURRING. OVER ERN LAKE SUPERIOR...LES HAS UNDERGONE SOME REORGANIZATION THIS AFTN...AND THE EXPECTED HVY BAND OF LES ALONG WIND SHIFT HAS FINALLY TAKEN SHAPE FROM NEAR THE HURON ISLANDS TO GRAND MARAIS. BAND IS VERY NARROW...BUT 0.5 DEGREE REFLECTIVITY IMAGERY FROM KMQT RADAR IS SHOWING INCREASING AREA OF GREATER THAN 28DBZ ECHOES. SO 1-3 INCH/HR SNOW RATES ARE PROBABLY COMMON IN THIS NARROW BAND OF SNOW. AS SHORTWAVE MENTIONED ABOVE CONTINUES SHEARING SE THIS EVENING... SYNOPTIC ENHANCEMENT TO LES WILL END EARLY THIS EVENING AS INDICATED BY DEEP LAYER QVECTOR CONVERGENCE SHIFTING E OF THE AREA. THIS FORCING LATE AFTN/EARLY EVENING WILL ASSIST THE MAIN BAND OF LES ON WIND SHIFT WHICH IS DROPPING THRU SCNTRL/SE LAKE SUPERIOR ATTM. COULD SEE A QUICK 2-3INCHES OF SNOW FROM THIS LES BAND PROVIDED IT DOES NOT BECOME NEARLY STATIONARY. FEEL CONFIDENT THAT WIND SHIFT WILL PROGRESS STEADILY THRU ERN ALGER/LUCE COUNTIES THIS EVENING WHICH WOULD KEEP BAND ON THE MOVE AND LIMIT ACCUMULATIONS. FARTHER W...WILL NEED TO KEEP AN EYE ON WRN ALGER COUNTY. AS WINDS BECOME NW...LAND BREEZE OFF HURON MOUNTAINS COULD RESULT IN THE TAIL END OF THIS BAND BECOMING STATIONARY FROM AROUND BIG BAY TOWARD THE AREA FROM SHOT POINT TO MUNISING. OTHERWISE...WITHOUT FOCUSED CONVERGENCE...LES THRU THE NIGHT SHOULD BE ON THE LIGHT SIDE (GENERALLY 1-3 INCHES) WITH INVERSION SETTING UP AROUND 4KFT. OUT W...LES SHOULD BECOME SCT OVER THE KEWEENAW AS WINDS VEER NNW WITH ISLE ROYALE LIMITING FETCH. LES SHOULD BECOME FOCUSED FARTHER S INTO ONTONAGON/GOGEBIC COUNTIES. ICE COVER EXTENDS FROM THE APOSTLE ISLANDS TO NEAR THE LOCATION OF WRN LAKE SUPERIOR BUOY. ALTHOUGH THE ICE COVER IS NOT SOLID...IT WILL WORK TO LIMIT HEAT/MOISTURE FLUXES AND WILL HAVE SOME IMPACT ON LES COVERAGE INTO GOGEBIC COUNTY. HAVE THUS CONFINED NUMEROUS SHSN COVERAGE TO ONLY A SMALL PART OF THE COUNTY N OF KIWD. AS FOR TEMPS...LOWERED MINS INLAND TONIGHT A FEW DEGREES WITH A BIT LESS CLOUD COVER THAN ORIGINALLY EXPECTED. WOULDN`T BE SURPRISED TO SEE -10F OR LOWER AT THE USUAL COLD SPOTS OVER THE INTERIOR W HALF. ON MON...WINDS WILL SLOWLY VEER TO A N TO NE DIRECTION AS SFC HIGH PRES RIDGE BUILDS E ACROSS ONTARIO. HOWEVER...THERE IS LITTLE CHANGE WITH RESPECT TO INVERSION HEIGHTS/MOISTURE PROFILES. SO...LES WILL REMAIN ON THE LIGHT SIDE (SUB ADVY ACCUMULATIONS). THOUGHT ABOUT LOWERING POPS INTO THE CHC CATEGORY OVER THE KEWEENAW...BUT WITH WINDS VEERING N...FETCH WILL ACTUALLY IMPROVE. EVEN SO...WITH A N WIND...THERE WILL BE A TENDENCY FOR DIVERGENCE OVER THE KEWEENAW DUE TO LAND BREEZE COMPONENTS OVER LAND. THIS SHOULD AT LEAST KEEP ACCUMULATIONS LIGHTER THAN WHAT WILL OCCUR FROM ROCKLAND TO THE VCNTY OF THE PORCUPINE MOUNTAINS AND OVER NCNTRL UPPER MI. .LONG TERM (MON NIGHT THROUGH NEXT SUN)... NORTHERLY WINDS AND H85 TEMPS NEAR -20C WILL KEEP LES GOING CLOSE TO LK SUPERIOR. WX MAY GET MORE MUDDLED LATER MON NIGHT INTO TUE AS RUC 13 AND LOCAL WRF-ARW INDICATE LAND BREEZES BEGIN TO DOMINATE LOWER LEVEL WINDS. IDEA MAKES SOME SENSE AS TEMPS WILL BE REALLY COOLING OVR FAR EASTERN UPR MI AS WINDS ARE FM NORTHEAST. SOME SCENARIOS EVEN RESULT IN PUSHING ANY LES COMPELTELY OFFSHORE OF NCNTRL AREAS OUT INTO LK SUPERIOR. NOT SURE HOW THIS SETUP WILL PLAY OUT...BUT FOR NOW DID SHOW A RETREATING TREND TO THE LES MON NIGHT INTO TUE AM BEFORE SYNOPTIC FLOW FM N STRENGTHENS AGAIN. AIRMASS IS DRY AS MAIN MOISTURE WILL BE TIED UP TO SIG STORM AFFECTING CNTRL PLAINS INTO OHIO VALLEY DURING THIS TIME. IF THE ASSOCIATED SFC TROUGH WITH THAT LOW COULD PROGRESS FARTHER NORTH...THEN ONGOING LES MAY GET A BOOST. AS IT STANDS NOW...LES SHOULD BE PRETTY MINIMAL WITH INVERSIONS WELL BLO H85. NE WINDS MAKE LES A NON ISSUE OVR LUCE COUNTY...SO LOWERED TEMPS A BIT TO ACCOUNT FOR THE EASTERLY DRAINAGE FLOW OUT OF ONTARIO ALLOWING TEMPS TO PLUMMET. HIGH RESOLUTION GUIDANCE INDICATES TEMPS TOWARD 25 BLO ZERO MON NIGHT OVR FAR EAST. CERTAINLY PLAUSIBLE IN LOCAL COLD SPOTS WHERE SKIES CAN CLEAR AND WINDS BECOME CALM. WHILE LARGE STORM MOVES INTO THE NORTHEAST CONUS...UPR LOW AND POOL OF COLD AIR SINKS ACROSS UPR LAKES BY WED. ON AVERAGE H85 TEMPS FALL TO -20C TO -25C 12Z WED THROUGH 12Z THU. AT SFC...CYCLONIC N/NW FLOW BTWN STRONG LOW OFF OF NEW ENGLAND AND SPRAWLING HIGH OVR CNTRL CANADA INTO PLAINS WILL GENERATE MODERATE LES. LES WILL LIKELY BECOME HEAVY FOR A PERIOD LATER WED INTO THU AS UPR LOW/LARGE SCALE LIFT/10KFT INVERSION/MOISTURE TO 10-15KFT SWEEPS ACROSS UPR GREAT LAKES. NW-N WINDS IN LOWER LAYERS AS ENHANCING FACTORS ARE BOOSTING LES. EXTENDED LIKELY POPS INTO THU NIGHT-FRI NEAR LK SUPERIOR. UPR LOW SHIFTS TOWARD NEW ENGLAND ON FRI WITH WINDS GRADUALLY BACKING TOWARD A WEST DIRECTION BY SAT. CLIPPER SYSTEM LOOKED LIKE IT WAS GOING TO AFFECT UPR LAKES FRI-SAT. NOW...AS MAIN UPR LOW IS TRENDING SLOWER IN EXITING THE CONUS...THAT SYSTEM STAYS WELL TO THE SW OF THE REGION. KEPT SMALL POPS IN AS WEAKER NORTHERN STREAM TROUGH MOVES THROUGH LATE FRI INTO SAT. MORE NW FLOW LES ON SUN. INTERESTING THAT SIGNS ARE BEGINNING TO EMERGE IN LATEST LONG RANGE GUIDANCE THAT A PATTERN CHANGE COULD START TAKING SHAPE 7-10 DAYS OUT. ACCORDING TO GFS/ECMWF LOOKS LIKE MORE TROUGHING DEVELOPS OVR EASTERN PACIFIC AS STRONGER JET SETS UP FARTHER NORTH TOWARD GULF OF AK. THIS LEADS TO RIDGE OVR WEST CONUS AND TROUGH OVR ERN CANADA AND CONUS BOTH BEGINNING TO MOVE EASTWARD. RESULT IS A WARMER PATTERN FOR MUCH OF THE COUNTRY...INCLUDING UPR GREAT LAKES. && .MQT WATCHES/WARNINGS/ADVISORIES... HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. && $$ UPDATE...VOSS SHORT TERM...ROLFSON LONG TERM...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
436 PM EST SAT FEB 10 2007 .SHORT TERM (TONIGHT AND SUNDAY)... H5 HEIGHTS INDICATE A RIDGE OVR WESTERN NORTH AMERICA WITH TROUGHING OVR EASTERN CANADA INTO THE GREAT LAKES AND NORTHEAST UNITED STATES. POLAR VORTEX HAS SUNK INTO NORTHERN ONTARIO WITH H5 HEIGHTS BLO 500 DAM. COUPLE OF SHORTWAVES WEST OF THE GREAT LAKES TODAY WILL SWING TOWARD THE AREA OR JUST TO THE SOUTH INTO SUNDAY. ISENTROPIC LIFT ON THE 280K SFC WILL PROVIDE A GOOD SWATH OF MID CLOUDS INTO SUN...BUT SYNOPTIC PCPN SHOULD REMAIN FARTHER S OVR WI WHERE LOWER LEVEL MOISTENING IS A BIT MORE PRONOUNCED. AS HAS BEEN THE CASE FOR THE LAST WEEK...ANY PCPN OVR UPR MI WILL BE CAUSED BY LK SUPERIOR. LES RIGHT NOW IS PRETTY MUCH NON EXISTENT. INVERSION LOWERING BLO H9 AS SEEN ON 12Z KINL SOUNDING/EARLY AFTN TAMDAR FM CYQT IS CAUSING THIS TREND. TEMPS AT TOP OF INVERSION CONTINUE TO WARM ALSO... NEARING -15C BY 00Z. LOBES OF LARGE SCALE LIFT FM POLAR VORTEX DROPPING TOWARD LK SUPERIOR LATE TONIGHT/APPROACHING SHORTWAVE FM THE WEST SHOULD BOOST LES AFT MIDNIGHT. LOWER LEVEL WINDS ALSO BECOME LESS SHEARED FM THE WEST AND CONVERGENCE PICKS UP FM SFC-H9 AS WELL. SO...EXPECT LES TO GET SOMEWHAT BETTER ORGANIZED IN THE OVERNIGHT. LOCAL HIGHER RESOLUTION WRF-ARW AND RUC13 INDICATE GREATEST CONVERGENCE OVR KEWEENAW 09Z-18Z SUN AS NW WINDS OVR LK SUPERIOR MEET THE STUBBORN W/SW FLOW OVR LAND. EVEN WITH THESE POSITIVES...INVERSION HEIGHTS STILL ONLY TOP OUT AROUND H85...SO CONVECTIVE DEPTH DOES NOT LOOK TOO IMPRESSIVE. THIS WAS PRIMARY REASON NOT TO GO WITH WARNING. INSTEAD...WILL ISSUE A LES/BLSN ADVY FOR KEWEENAW PENINSULA. ADDED BLSN AS EXPECT BLYR WINDS TO BE BTWN 20-30 MPH LATER TONIGHT THROUGH SUN. WINDS SHIFTING NW IN MIXED LAYER AFT 18Z SHOULD DIMINISH LES ON KEWEENAW SUN AFTN...SO WILL END ADVY AT THAT TIME. OTHER CONCERN IS OVR FAR NE CWA...WHERE AN ADVY MAY BE NEEDED ON SUN. NOT ISSUING THAT NOW SINCE IT IS STILL LATER IN THE SECOND PERIOD. BACK TO WINDS...MODELS HAVE STRUGGLED LATELY WITH WIND SPEEDS OVR LK SUPERIOR. LAST TWO GALE EVENTS...NAM/GFS HAVE UNDERESTIMATED MAX WINDS BY 5-10KT AND IT IS HAPPENING AGAIN TODAY...WITH GALE FORCE GUSTS OBSERVED MOST DAY ON LK SUPERIOR AND 30 KT AT MOST IN MODEL GUIDANCE. SINCE WINDS ARE PROGGED TO INCREASE THROUGH H85 TONIGHT AHEAD OF SHORTWAVES...WENT WITH GALE WARNING ON LK SUPERIOR THROUGH SUN AM. MOS TEMPS FOR TONIGHT/SUNDAY SEEMED REASONABLE. LOWERED TEMPS OVR INLAND WEST HALF (5 TO 10 BLO ZERO) AS CLEAR SKIES THIS EVENING AND FAIRLY LGT WINDS MAY RESULT IN TEMPS DROPPING QUICKLY TOWARD CURRENT DEWPOINTS. .LONG TERM (SUN NIGHT THROUGH SAT)... COLD FRONT REACHING THE KEWEENAW SUN AFTN WILL EXIT THE FCST AREA SUN EVENING. IN ITS WAKE...850MB TEMPS DROP INTO THE -20 TO -24C RANGE OVER LAKE SUPERIOR BY 12Z MON. ALTHOUGH THERE IS PLENTY OF INSTABILITY FOR LES....NAM HAS COME AROUND TO THE GFS WITH RESPECT TO LOWER INVERSIONS OF 4-5KFT AND A LESS SUPPORTIVE MOISTURE PROFILE. SO...AFTER INTIAL BURST OF SNOW WITH FROPA...LES SHOULD SETTLE DOWN TO A RELATIVELY LIGHT INTENSITY THROUGH SUN NIGHT. VEERING WINDS WITH HIGH PRES BUILDING E THRU MANITOBA/ONTARIO WILL ALSO KEEP BANDS SHIFTING...KEEPING ACCUMULATIONS DOWN. IN ADDITION...LARGE SCALE ANTICYCLONIC FLOW WILL BE ANOTHER NEGATIVE. HOWEVER...THERE ARE INDICATIONS THAT LOCAL CONVERGENCE OR EVEN A MESOLOW WILL DEVELOP OVER SCNTRL LAKE SUPERIOR AS VEERING LARGE SCALE WINDS ARE ENHANCED BY LAND BREEZE OFF ONTARIO TO TAKE ON A MORE ERLY COMPONENT OVER ERN SUPERIOR. WILL NEED TO KEEP AN EYE ON THIS POTENTIAL WHICH COULD LEAD TO LOCAL HVY LES IN MARQUETTE OR ALGER COUNTIES LATE SUN NIGHT. ON MON...WINDS CONTINUING VEERING TO A NE DIRECTION...BUT THERE IS LITTLE CHANGE WITH RESPECT TO INVERSION HEIGHTS/MOISTURE PROFILES. SO...LES WILL REMAIN ON THE LIGHT SIDE (SUB ADVY ACCUMULATIONS). IF A MESOLOW DOES DEVELOP OVER SCNTRL LAKE SUPERIOR LATE SUN NIGHT... SNOW COULD BE LOCALLY HVY THRU MON MORNING OVER A SMALL PART OF NCNTL UPPER MI. ALTHOUGH CORE OF COLDEST AIR PASSES JUST NE OF FCST AREA...TEMPS WILL PROBABLY STRUGGLE TO REACH 10F OVER THE HIGHER TERRAIN OF THE W AND NCNTL FCST AREA WITH 850MB TEMPS HOVERING AROUND -22C. TUE THRU SAT...OTHER THAN LES...THERE WON`T BE MUCH PCPN DURING THIS PERIOD UNDER A GENERAL DRY NW FLOW PATTERN. MAIN FCST ISSUE IS POTENTIAL OF A MIDLEVEL LOW TO DROP INTO THE UPPER GREAT LAKES MIDWEEK. 00Z/12Z FEB9 ECWMF/GFS/GLOBAL CANADIAN RUNS WERE IN GOOD AGREEMENT ON SUCH A SCENARIO. THE 00Z/12Z FEB10 ECMWF RUNS STILL SHOW THIS SOLUTION (JUST SLIGHTLY W AND SLIGHTLY DEEPER THAN FEB9 RUNS). THE 00Z/06Z/12Z GFS RUNS HAVE BACKED AWAY FROM THE MIDLEVEL LOW OVER THE UPPER LAKES AND NOW ONLY SHOW AN OPEN WAVE SWINGING THRU THE UPPER LAKES WED OR KEEP MIDLEVEL LOW N OF LAKE SUPERIOR. THE 00Z GLOBAL CANADIAN SUPPORTS THE ECWMF...BUT WITH HEIGHTS NOT NEARLY AS LOW AS THE ECMWF (500MB HEIGHT WITH MIDLEVEL LOW OVER NE LWR MI 00Z THU IN THE CANADIAN SOLUTION IS 180M HIGHER THAN THE ECWMF). THE 00Z UKMET WHICH HAS SHOWN VERY POOR RUN-TO-RUN CONSISTENCY DOES SUPPORT AN ECMWF/CANADIAN SOLUTION BUT IS ABOUT 24HR SLOWER WITH THE WHOLE PROGRESSION OF MIDLEVEL LOW. 12Z UKMET NOW LOOKS JUST LIKE THE ECWMF WITH TIMING AND DEPTH OF MIDLEVEL SYSTEM. 12Z CANADIAN HAS TRENDED DEEPER AND FARTHER W WITH MIDLEVEL LOW AND JUST DRIFTS IT ACROSS THE WRN GREAT LAKES WED AND THU. AT THIS POINT...DIFFERENCES IN THE DETAILS FOR A SYSTEM 3-5DAYS OUT YET WON`T MAKE TOO MUCH DIFFERENCE IN THE BASIC WEATHER HERE AS ALL SUGGEST A GENERAL NRLY FLOW LES PATTERN TUE/WED WITH LIKELY POPS NEAR LAKE SUPERIOR. IF THE ECMWF SOLUTION WORKS OUT...THERE WOULD BE A SIGNIFICANT LAKE EFFECT/LAKE ENHANCED SNOW EVENT FOR AREAS FAVORED BY NRLY LOW-LEVEL WINDS LATE TUE THRU WED NIGHT. ALTHOUGH NON GFS SOLUTIONS SUPPORT POTENTIAL FOR SIGNIFICANT SNOW... CONFIDENCE IS NOT HIGH ENOUGH RIGHT NOW TO START HIGHLIGHTING POSSIBILITY IN HAZARDOUS WX OUTLOOK. LES WILL WIND DOWN WITH MODERATING AIRMASS AND BACKING WINDS THU AND SHOULD ACTUALLY END FRI AS 850MB TEMPS CONTINUE TO RISE. DESPITE REASONABLE GFS/ECMWF AGREEMENT LATE IN THE WEEK...HAVE LOW CONFIDENCE ON TIMING NEXT SHORTWAVE APPROACHING UPPER LAKES LATE FRI. HAVE INCLUDED LOW CHC POPS FOR -SN FRI NIGHT INTO SAT FOR THIS SYSTEM. TEMPS WILL BE BELOW NORMAL EARLY IN THE PERIOD AND WILL RISE TO AROUND NORMAL BY THE END OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW AND BLSN ADVY 06Z UNTIL 18Z SUN MIZ001-003. GALE WARNING LAKE SUPERIOR. HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. && $$ JLA (SHORT TERM) ROLFSON (LONG TERM)
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
335 AM EST SAT FEB 10 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW NW ARCTIC BRANCH FLOW ALF OVER THE GRT LKS BTWN PERSISTENT HI AMPLITUDE RDG OVER WRN CAN AND VORTEX CENTERED IN SE CAN. ONE SHRTWV EMBBEDDED WITHIN THIS FLOW HAS TRACKED ACRS NRN WI INTO NRN LWR MI TNGT WHILE ANOTHER HAS DROPPED SE THRU NW ONTARIO TOWARD ANJ. THE TRACK OF THESE SHRTWVS HAS CAUSED LLVL WINDS TO VEER MORE NW THE LAST COUPLE OF HRS...WHICH HAS RESULTED IN LES THAT WAS MAINLY OVER THE KEWEENAW AND OVER THE OPEN WATERS OF ERN LK SUP TO SHIFT INTO ONTONAGON COUNTY AND INTO ALGER/LUCE/NRN SCHOOLCRAFT COUNTIES. MQT 88D SHOWS HIER REFLECTIVITIES IN THE BANDS TO THE E ARE FAIRLY LIMITED...BUT A FEW RETURNS IN THE 24-28DBZ RANGE NOTED WITHIN THE CLOSER BANDS. NW GALE FORCE WINDS OBSVD AT PILM4/STDM4...AND WIND GUSTS ARND 40 MPH NOTED AT P59. LES APPEARS WEAKER OVER THE WRN ZNS WITH SHORTER FETCH (LIMITED BY SOME ICE COVG) AND CLOSER PROXIMITY TO LO INVRNS ARND H9-925 NOTED ON THE 00Z INL/YPL RAOBS AND 03Z TAMDAR SDNG FM CYQT AS WELL AS DRY SUB INVRN LYR (SFC DWPTS UPSTREAM OF WRN LK SUP IN THE -15C TO -20C RANGE). HOWEVER...INL SDNG DOES SHOW SOME MSTR ABV THE INVRN BTWN H925-825. 00Z APX SDNG/TAMDAR SDNG FM CIU HINT THAT INVRN IN AREAS DOWNSTREAM OF LK MODERATION IS H8-85. OVER THE INTERIOR ZNS...SKIES ARE CLR-PCLDY...AND TEMPS HAVE FALLEN AOB 0F AT A NUMBER OF SPOTS. OTRW...SHRTWV RDGING NOTED BLDG INTO SASKATCHEWAN/MANITOBA BEHIND ONTARIO SHRTWV. 00Z YQD SDNG IS QUITE DRY (PWAT 0.06 INCH) AND EXCESSIVELY STABLE (INVRN BASE H95). MAIN FCST CONCERNS THE NEXT COUPLE OF DAYS REVOLVE ARND LES TRENDS/ AMTS/HEADLINES ASSOCIATED WITH SHRTWVS EMBEDDED IN NW ARCTIC BRANCH FLOW AND DROP SE OVER THE GRT LKS. FOR TDAY...SHRTWV RDGING OVER SCNTRL CAN PROGGED TO DRIFT INTO THE UPR GRT LKS. GFS/NAM FCST SDNGS SHOW INVRN BASE AT ERY DROPPING FM H85 THIS MRNG TO H9 BY 00Z SUN WHILE LLVL FLOW BACKS MORE W. INVRN BASE AT CMX FCST TO DROP FM H875 TO H9 (GFS) OR EVEN H925 (NAM) BY THIS EVNG WITH ARPCH OF RDG. ALTHOUGH MOIST H9-85 LYR ON THE INL SDNG MAY SUSTAIN THE LES THRU THE MRNG...SUSPECT ACTIVITY WL REALLY WANE THIS AFTN WITH ARRIVAL OF DRIER AIR W-NW OF INL AND LOWER INVRN BASE. ALTHOUGH RELATIVELY WEAK RADAR RETURNS OVER THE E/SHIFTING NATURE OF LES BANDS SO FAR HAVE PROBABLY LIMITED SN ACCUMULATION THERE...WL EXTEND LES/BLSN ADVY (BLSN PER GALE FORCE WINDS OBSVD OVER LK SUP) THRU THE MRNG FOR ALGER/LUCE ZNS TO ACCOUNT FOR WINDOW OF BETTER MSTR/FVRBL WIND DIRECTION BEFORE INVRN FALLS/FLOW BACKS TOO WSW LATER IN THE AFTN AND DRIER SUB INVRN AIR ARRIVES. DESPITE POTENTIAL FOR FVRBL DENDRITIC SN GROWTH WITH MIXED LYR TEMPS IN THE -12C TO -20C RANGE...STEADILY SHIFTING WINDS/LLVL CNVGC AFT 15Z SHOULD LIMIT THE POTENTIAL FOR WRNG SN AMTS. OVER THE INLAND ZNS...SKIES SHOULD BE PARTLY-MOSUNNY. CONSIDERING THE HI STABILITY OF UPSTREAM AIRMASS/ MAX TEMPS ON FRI/BETTER RECENT VERIFICATION OF THE LO END OF MOS GUIDANCE...WL TEND TOWARD THE LOWER GFS MOS GUIDANCE FOR HI TEMPS TDAY. TNGT...GFS/NAM SHOW ANOTHER SHRTWV DROPPING INTO THE UPR GRT LKS FM SCNTRL CAN. THIS WAVE IS RATHER SHEARED HOWEVER...SO THE FCST IMPACT ON INVRN HGT APPEARS TO BE RATHER MINIMAL. THE GFS SHOWS SOMEWHAT MORE RESPONSE AT CMX WITH INVRN BASE RISING FM H9 TO H875 WITH SOME LO-MID LVL MOISTENING AS WELL. WITH FLOW BACKING TO A MORE 260 DIRECTION...EXPECT LES OVER THE W TO SHIFT TO MAINLY JUST THE KEWEENAW. IN FACT...RECENT RUC13 SHOWS FLOW ENHANCED BY LAND BREEZE BACKING SUFFICIENTLY THAT MODEL QPF IS ALMOST ENTIRELY N OF CMX. IF UPSTREAM AIRMASS WERE MOISTER/SHRTWV STRONGER/INVRN HIER AND ICE OVER THE SRN PORTIONS OF WRN LK SUP WERE ABSENT...POTENTIAL FOR MORE INTENSE DOMINANT BAND IN LAND BREEZE/SYNOPTIC SCALE WNW FLOW CNVGC RUNNING THE LENGTH OF WRN LK SUP TO CAUSE HEAVY SN WOULD BE HI. HOWEVER... NEGATIVES MENTIONED ABV SUG MORE LIKELY SCENARIO WL BE A SUB ADVY EVENT...WITH UP TO 4 INCHES FCST OVER HIER TERRAIN N OF CMX PER RUC13 QPF ARND 0.15 INCH AND FVRBL SN/WATER RATIO. SINCE TEMPS ARND -15C WITHIN MIXED LYR ARE FVRBL FOR DENDRITIC SN GROWTH... REMAIN WARY OF POTENTIAL FOR ADVY SN WITH PERSISTENT LLVL CNVGC. OVER THE E... INCRSG LAND BREEZE WSW FLOW SHOULD PUSH LINGERING LES INTO THE OPEN WATERS OF ERN LK SUP...BUT WL RETAIN CHC POPS NEAR THE SHORE E OF THE PIX ROCKS IN CASE FLOW ABV SHALLOW ARCTIC. SKIES WL BE MARRED BY ONLY SOME HI CLDS ASSOCIATED WITH THE SHRTWV OVER THE INTERIOR...WITH TEMPS NEAR LO END OF MOS GUIDANCE WITH LAND BREEZE/ SHALLOW ARCTIC AIR DESPITE STEADY W WIND/SOME HI CLD. A MORE IMPORTANT SHRTWV/COLD FNT IS FCST TO APRCH ON SUN WITH DPVA/ H85-5 QVECTOR CNVGC IN ADVANCE OF THIS SYS FCST BY GFS/NAM/CNDN MODELS TO RAISE INVRN BASE OVER THE NW AND E TOWARD H8 AND MOISTEN THE LLVLS. CONSIDERING THE POTENTIAL FOR DECENT SN LATER SAT NGT OVER THE KEWEENAW AND APRCH OF THIS SYS/FVRBL TEMPS FOR DENDRITIC SN GROWTH BEFORE ARRIVAL OF COLDER AIR LATE BEHIND THE COLD FROPA... DECIDED TO ISSUE AN LES WATCH FOR THAT AREA SAT NGT INTO SUN BEFORE SHIFTING WINDS TO A MORE UNFVRBL 330 DIRECTION IN THE AFTN DIMINISH THE ACTIVITY THERE. RUC13 SHOWS WSHFT EARLIER IN THE MRNG...BUT NAM/GFS HOLD ON TO FVRBL 270-280 FLOW LONGER UNDER INCRSG DPVA. HAVE TO ADMIT DOUBTS ABOUT ICE COVER/SHORTER FETCH/UPSTREAM DRY AIR MIGHT CUT BACK ON SN AMTS...BUT CONFIDENT ENUF THAT AT LEAST AN ADVY SN WL OCCUR SAT NGT THRU SUN MRNG. SINCE MAIN SN BAND WL BE OFFSHORE OVER THE E WHEN THE SHARPER DYNAMICS ARRIVE...WL HOLD OFF ON ANY ADDITIONAL HEADLINES THERE ATTM. AS LLVL WINDS SHIFT TO MORE NNW SUN NGT...MORE SGNFT LES WL SHIFT MORE TOWARD IWD/MQT. && .MQT WATCHES/WARNINGS/ADVISORIES... HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. LAKE EFFECT SNOW AND BLOWING SNOW ADVY UNTIL 17Z SAT MIZ006-007. LES WATCH 03Z-22Z SUN MIZ001-003. && $$ KC
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
405 AM EST MON FEB 12 2007 .SHORT TERM (TODAY)... WATER VAPOR LOOP SHOWS AN UPPER LOW SPINNING OVER THE HUDSON BAY...WITH THE NEXT TROUGH MOVING THROUGH THE ROCKIES. ACARS 400-250MB WIND OBSERVATIONS REVEAL A 100-140KT JET FROM LAKE WINNIPEG SOUTHEAST THROUGH THE MID ATLANTIC...WITH A SECOND 100-140KT JET FROM THE CENTRAL GULF OF MEXICO NORTHEAST PHASING WITH THE FIRST JET OVER THE WESTERN ATLANTIC (WHERE WINDS INCREASE TO 170 KNOTS). A 140-160KT JET EXTENDED FROM THE PACIFIC OCEAN INTO NORTHERN MEXICO. 03Z SURFACE ANALYSIS PLACED A 1028MB CYCLONE ACROSS THE CENTRAL APPALACHIANS...AND A 1027MB ANTICYCLONE OFF THE NORTH CAROLINA COAST (SEPARATED BY A LEE TROUGH). SEVERAL WARM FRONTS WERE DEVELOPING FROM THE PLAINS INTO THE MIDWEST. A COLD FRONT EXTENDED FROM A 1008MB CYCLONE IN WESTERN QUEBEC SOUTHWEST ACROSS THE UPPER MIDWEST. UPPER LEVEL CLOUDINESS IS RAPIDLY DEVELOPING OVERHEAD AS DIFFLUENCE ALOFT INCREASES WITH THE STRENGTHENING PHASED JET ACROSS THE WESTERN ATLANTIC. WARM ADVECTION WILL SERVE TO THICKEN AND LOWER CEILINGS THROUGH THE DAY...WHILE LIGHT PRECIPITATION DEVELOPS DURING THE LATE AFTERNOON TO THE SOUTH AND WEST OF THE BALTIMORE AND WASHINGTON METRO AREAS. THERMAL STRUCTURE AND EVAPORATIONAL COOLING SHOULD SUPPORT MAINLY SNOW ACROSS THE PAN HANDLE OF WEST VIRGINIA/MARYLAND...WITH A RAIN/SNOW MIX FURTHER SOUTH. CHANCES OF ACCUMULATION DURING THE AFTERNOON HOURS ARE IN THE 20-30 PERCENT RANGE...AS ISENTROPIC LIFT ON THE 280-285K SURFACES APPEARS TOO WEAK TO COUNTERACT CONDENSATION PRESSURE DEFICITS. WITH +1C OF WARM ADVECTION BETWEEN 800-950MB ALREADY BETWEEN THE 0440Z DESCENT KIAD ACARS SOUNDING AND THE 00Z KIAD RAOB...FORECAST HIGHS WARMER THAN YESTERDAY. IF ENOUGH EVAPORATIONAL COOLING OCCURS EARLIER THAN FORECAST...TEMPERATURES MAY BE ON THE OPTIMISTIC SIDE. && .MEDIUM TERM (TONIGHT THROUGH TUESDAY NIGHT)... MODELS CONTINUE TO SHOW A HIGH IMPACT STORM AFFECTING THE REGION...MAINLY TUESDAY THROUGH EARLY WEDNESDAY...BUT THEY CONTINUE TO TREND TOWARD A WARMER SOLUTION WHICH WILL FAVOR MORE MIXED PRECIPITATION THAN SNOW OVER THE MID ATLANTIC. WITH THIS WARMER SOLUTION...A SIGNIFICANT FREEZING RAIN EVENT MAY OCCUR OVER OUR CWA. MODELS ALSO CONTINUE TO TREND SLOWER WITH THE ONSET OF PRECIPITATION MONDAY NIGHT. HAVE INITIALLY BACKED OFF ON PRECIPITATION MONDAY EVENING...MAINLY ALLOWING FOR RAIN AND SNOW ACROSS THE POTOMAC HIGHLANDS AND SHENANDOAH VALLEY IN THE EVENING WITH ISENTROPIC LIFT STRENGTHENING WELL AHEAD OF LOW PRESSURE OVER THE LOWER MISSISSIPPI VALLEY. PRECIPITATION WILL EXPAND FROM SOUTHWEST TO NORTHEAST AFTER MIDNIGHT...PER GFS AND NAM ISENTROPIC/OMEGA FIELDS. GIVEN THE PREFERRED GFS TEMPERATURE PROFILES...BELIEVE P-TYPE WILL BE ALL SNOW ACROSS THE NORTHERN HALF OF OUR CWA LATE MONDAY NIGHT INTO EARLY TUESDAY. IN THIS AREA...GFS ALSO INDICATES WEAK H7-H5 VECTOR DIVERGENCE ALONG WITH FRONTOGENETIC FORCING...AND A LIGHT ACCUMULATION OF SNOW MAY RESULT. ACROSS THE SOUTHERN HALF OF OUR CWA...SURFACE/BOUNDARY LAYER TEMPERATURES WILL HAVE COOLED BELOW FREEZING. HOWEVER...A NOSE OF WARM AIR A FEW THOUSAND FEET ABOVE THE GROUND WILL MAKE IT INTO THE POTOMAC HIGHLANDS...CENTRAL VIRGINIA AND LOWER SOUTHERN MARYLAND AREA. THIS WILL ALLOW FOR ANY SNOW TO MIX WITH AND THEN CHANGE TO SLEET AND FREEZING RAIN. THIS TREND OF MIXED PRECIPITATION TILTING NORTH AND WEST WILL CONTINUE THROUGHOUT TUESDAY AS A S/SE 850 MB LOW LEVEL JET INTENSIFIES. HOWEVER...TEMPERATURES NEAR THE SURFACE WONT MOVE MUCH ON TUESDAY...AND WILL REMAIN AT OR BELOW FREEZING PER GFS (AND MET) MOS GUIDANCE. SREFS HIGHLIGHT THE HIGH LIKELIHOOD OF MIXED PRECIPITATION. THE BALDWIN ALGORITHM FAVORS MORE SLEET THAN FREEZING RAIN...YET THE CZYS ALGORITHM INDICATES MOST OF OUR CWA WOULD BE AFFECTED BY FREEZING RAIN. CONCEPTUALLY...THE CZYS SCENARIO LOOKS MORE LIKELY...AND WHEN THE DURATION OF FREEZING RAIN IS COMBINED WITH MODEL QPF...A QUARTER TO HALF INCH OF ICE COULD RESULT. AN EXCEPTION MAY BE ACROSS LOWER SOUTHERN MARYLAND...WHERE BOTH ALGORITHMS AND OPERATIONAL GFS TEMPERATURE PROFILES INDICATE A CHANGEOVER TO RAIN TUESDAY NIGHT. TAKING ALL OF INTO ACCOUNT...WILL CONTINUE WITH THE WINTER STORM WATCH FOR THIS CYCLE...BUT ACCENTUATE THE FACT THAT THERE IS INCREASED CONFIDENCE THAT THIS STORM WILL HAVE PRIMARILY MIXED PRECIPITATION...AND THAT SIGNIFICANT ICE ACCUMULATIONS MAY RESULT. WOULD SURMISE THIS WILL PAVE THE WAY FOR THE NEXT SHIFT TO ISSUE WARNINGS OR ADVISORIES AS NECESSARY. && .LONG TERM (WEDNESDAY THROUGH SUNDAY)... 500MB TROUGH OVER THE OHIO RIVER VALLEY AT THE BEGINNING OF THE PERIOD. THIS FEATURE AND ITS ASSOCIATED SHORTWAVE WILL MOVE OFFSHORE DURING THE DAY ON WEDNESDAY...BUT A LONGWAVE TROUGH SETS UP OVER THE EASTERN SEABOARD THROUGH FRIDAY. THE TROUGH WILL FINALLY MOVE OFFSHORE LATE FRIDAY AS A SHORTWAVE DIVES SOUTH FROM CANADA AND MOVES EAST OVER THE REGION. AT THE SURFACE...A DOUBLE BARRELED LOW HAS FORMED OFF THE MID ATLANTIC COAST WITH THE PRIMARY LOW OVER THE DELMARVA PENINSULA. THIS FEATURE WILL CONTINUE UP THE EASTERN SEABOARD FOR THE REMAINDER OF WEDNESDAY. UPSLOPE SNOWS WILL BEGIN IN THE HIGHER TERRAIN ON THE BACKSIDE OF THE DEPARTING LOW PRESSURE SYSTEM. HIGH PRESSURE BUILDS IN FROM THE WEST ON THURSDAY. THE UPSLOPE PRECIP SHOULD END EARLY ON FRIDAY AS THE RIDGING MOVES OVERHEAD. RIDGING LINGERS THROUGH SATURDAY AS A FRONTAL BOUNDARY MOVES OVER THE CENTRAL PART OF THE COUNTRY AND INTO THE LOWER MISSISSIPPI VALLEY. THIS FRONTAL BOUNDARY IS EXPECTED TO COME THROUGH THE MID ATLANTIC DURING THE LATE WEEKEND. THE MOST DIFFICULT PERIOD FOR THE LONGER TERM FORECAST WAS THE WEDNESDAY TIME FRAME. THIS WILL BE A TRANSITION PERIOD AS THE LOW PRESSURE DEPARTS AND COLDER TEMPERATURES ALOFT WILL BEGIN TO SINK SOUTHWARD ONCE AGAIN. THE HIGHER TERRAIN WILL SWITCH BACK OVER THE ALL SNOW EARLY...WHILE THE CENTRAL CWFA SWITCHES OVER FROM FREEZING RAIN TO A SNOW/SLEET MIXTURE BY MID MORNING...WITH ALL SNOW EXPECTED IN THE AFTERNOON. THE FREEZING RAIN WILL LIKELY HANG AROUND UNTIL THE MID MORNING HOURS ALONG THE NORTHERN BAY....WHILE ALL RAIN CONTINUES OVER LOWER SOUTHERN MARYLAND. EXPECT AREAS ALONG THE WESTERN SHORE TO CHANGEOVER TO ALL SNOW BY THE LATE AFTERNOON. CHANGES TO THE GRIDS WERE MOSTLY CONFINED TO THE WEDNESDAY/THURSDAY TIME FRAME. THE WEATHER/POPS WERE ADJUSTED FOR LINGERING PRECIP ALONG THE WESTERN SHORE AND FOR PTYPE. IN ADDITION...HAVE GONE BELOW MOS FOR HIGH TEMPS ON WEDNESDAY DUE TO ICE/SNOW ON THE GROUND. WINDS SHOULD ALSO BE A FACTOR...AND HAVE INCREASED ON THE BACKSIDE OF THE LOW. OTHERWISE...DIDN`T REALLY DEVIATE FROM GUIDANCE AND MADE NO CHANGES PAST THURSDAY. && .AVIATION... WARM ADVECTION STRATUS WHICH IS NOT BEING HANDLED WELL BY ANY OF THE MODELS CONTINUES TO BUILD SOUTH FROM PENNSYLVANIA UNDERNEATH AN INVERSION NEAR 6KFT ON THE 00Z KIAD RAOB. TREND AFTER SUNRISE SHOULD BE A HALT TO SOUTHERN PROGRESS AND PROBABLY DISSIPATION ON THE SOUTHERN FRINGE DUE TO WARMING AND DIURNAL MIXING. MEANWHILE...UPPER LEVEL MOISTURE WILL BE BUILDING DOWN AND THICKENING THROUGH THE DAY. WARM ADVECTION WILL ALLOW CONTINUED SATURATION OF THE LOWER LEVELS DURING THE EVENING...WITH AREAS OF SNOW (RAIN/SNOW NEAR KCHO) DEVELOPING AS THE EVENING PROGRESSES. && .MARINE... 12Z MET/MAV MOS AT THOMAS POINT INDICATE SUSTAINED WINDS 5KT OR LESS TODAY. WITH A COL IN THE SURFACE PRESSURE ACROSS THE WATERS...EXPECT LIGHT WINDS. ICE COVERAGE ACROSS THE EXTREME NORTHERN BAY IS CLOSE TO 7-8 TENTHS. THE GRADIENT WILL BEGIN TO TIGHTEN ON TUESDAY AS SURFACE LOW PRESSURE NEARS THE REGION. HAVE GONE AHEAD AND RAISED A SMALL CRAFT ADVISORY FOR STRENGTHENING NORTHEAST WINDS. HAVE MADE SOME SIGNIFICANT CHANGES TO THE WINDS AND WIND GUSTS ON THE BAY FOR WEDNESDAY AND THURSDAY. WIND GUSTS PROBABLY SAW THE MOST EDITING AS BUFKIT SOUNDINGS DO INDICATE THAT GALES GUSTS ARE LIKELY FOR WEDNESDAY. SINCE WINDS ARE TYPICALLY UNDERDONE BY THE MODELS...HAVE GONE AHEAD AND BUMPED UP THE GUST POTENTIAL TO 40 KT DURING THE DAY ON WEDNESDAY WITH 35 KT FOR WEDNESDAY NIGHT. SCA CONDITIONS ARE LIKELY TO PERSIST THROUGH FRIDAY. SINCE WEDNESDAY/THURSDAY IS STILL A LITTLE FAR OUT FOR A HEADLINE...WILL ONLY HAVE MENTION IN THE SYNOPSIS. && .TIDES... CURRENT TIDAL DEPARTURES ARE A HALF TO THREE QUARTERS OF A FOOT ABOVE ASTRONOMICAL PREDICTIONS. THE LUNAR CYCLE IS WANING TO A QUARTER MOON (32 PERCENT FULL). BOTH THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM AND NOAA EXTRATROPICAL STORM SURGE MODELS HAVE MISSED THE OBSERVED POSITIVE TIDAL DEPARTURES. PRESSURE GRADIENT WILL TIGHTEN AHEAD OF THE STORM SYSTEM TUESDAY...ENCOURAGING TIDAL DEPARTURES TO INCREASE FURTHER. WHILE ASTRONOMICAL TIDES ARE LOWEST FOR THE MONTH...TIDAL DEPARTURES WILL HAVE TO BE MONITORED THROUGH WEDNESDAY MORNING. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR DCZ001. MD...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR MDZ003>007-009>011-013-014-016>018-501-502. VA...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR VAZ021-025>031-036>042-050>057. WV...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR WVZ050>055-501>504. MARINE...SMALL CRAFT ADVISORY FROM 1 PM TUESDAY TO 4 AM EST WEDNESDAY FOR ANZ530>537. && $$ SHORT TERM/AVIATION/TIDES...ROGOWSKI MEDIUM TERM...PELOQUIN LONG TERM...NWL MARINE...ROGOWSKI/NWL
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
1023 AM EST MON FEB 12 2007 .SHORT TERM /REST OF TODAY/... TEMPERATURES AROUND THE REGION AT 15Z ARE ALREADY IN THE LOWER TO MID 30S. HIGH CLOUDS CONTINUE TO SPREAD ACROSS THE MID ATLANTIC AHEAD OF THE H5 TROUGH DEVELOPING IN THE SOUTHERN PLAINS AND FAST ZONAL FLOW ALOFT. HIGHS IN THE 40 TO 45 RANGE IN THE CURRENT FORECAST LOOK GOOD...DESPITE CLOUD COVER. WINDS WILL REMAIN LIGHT THROUGH THE AFTERNOON GIVEN THE VERY WEAK SFC PRESSURE GRADIENT. NO UPDATES TO ZONE FORECAST PACKAGE PLANNED. && .PREV DISCUSSION... /ISSUED 405 AM EST MON FEB 12 2007/ SHORT TERM (TODAY)... WATER VAPOR LOOP SHOWS AN UPPER LOW SPINNING OVER THE HUDSON BAY...WITH THE NEXT TROUGH MOVING THROUGH THE ROCKIES. ACARS 400-250MB WIND OBSERVATIONS REVEAL A 100-140KT JET FROM LAKE WINNIPEG SOUTHEAST THROUGH THE MID ATLANTIC...WITH A SECOND 100-140KT JET FROM THE CENTRAL GULF OF MEXICO NORTHEAST PHASING WITH THE FIRST JET OVER THE WESTERN ATLANTIC (WHERE WINDS INCREASE TO 170 KNOTS). A 140-160KT JET EXTENDED FROM THE PACIFIC OCEAN INTO NORTHERN MEXICO. 03Z SURFACE ANALYSIS PLACED A 1028MB CYCLONE ACROSS THE CENTRAL APPALACHIANS...AND A 1027MB ANTICYCLONE OFF THE NORTH CAROLINA COAST (SEPARATED BY A LEE TROUGH). SEVERAL WARM FRONTS WERE DEVELOPING FROM THE PLAINS INTO THE MIDWEST. A COLD FRONT EXTENDED FROM A 1008MB CYCLONE IN WESTERN QUEBEC SOUTHWEST ACROSS THE UPPER MIDWEST. UPPER LEVEL CLOUDINESS IS RAPIDLY DEVELOPING OVERHEAD AS DIFFLUENCE ALOFT INCREASES WITH THE STRENGTHENING PHASED JET ACROSS THE WESTERN ATLANTIC. WARM ADVECTION WILL SERVE TO THICKEN AND LOWER CEILINGS THROUGH THE DAY...WHILE LIGHT PRECIPITATION DEVELOPS DURING THE LATE AFTERNOON TO THE SOUTH AND WEST OF THE BALTIMORE AND WASHINGTON METRO AREAS. THERMAL STRUCTURE AND EVAPORATIONAL COOLING SHOULD SUPPORT MAINLY SNOW ACROSS THE PAN HANDLE OF WEST VIRGINIA/MARYLAND...WITH A RAIN/SNOW MIX FURTHER SOUTH. CHANCES OF ACCUMULATION DURING THE AFTERNOON HOURS ARE IN THE 20-30 PERCENT RANGE...AS ISENTROPIC LIFT ON THE 280-285K SURFACES APPEARS TOO WEAK TO COUNTERACT CONDENSATION PRESSURE DEFICITS. WITH +1C OF WARM ADVECTION BETWEEN 800-950MB ALREADY BETWEEN THE 0440Z DESCENT KIAD ACARS SOUNDING AND THE 00Z KIAD RAOB...FORECAST HIGHS WARMER THAN YESTERDAY. IF ENOUGH EVAPORATIONAL COOLING OCCURS EARLIER THAN FORECAST...TEMPERATURES MAY BE ON THE OPTIMISTIC SIDE. MEDIUM TERM (TONIGHT THROUGH TUESDAY NIGHT)... MODELS CONTINUE TO SHOW A HIGH IMPACT STORM AFFECTING THE REGION...MAINLY TUESDAY THROUGH EARLY WEDNESDAY...BUT THEY CONTINUE TO TREND TOWARD A WARMER SOLUTION WHICH WILL FAVOR MORE MIXED PRECIPITATION THAN SNOW OVER THE MID ATLANTIC. WITH THIS WARMER SOLUTION...A SIGNIFICANT FREEZING RAIN EVENT MAY OCCUR OVER OUR CWA. MODELS ALSO CONTINUE TO TREND SLOWER WITH THE ONSET OF PRECIPITATION MONDAY NIGHT. HAVE INITIALLY BACKED OFF ON PRECIPITATION MONDAY EVENING...MAINLY ALLOWING FOR RAIN AND SNOW ACROSS THE POTOMAC HIGHLANDS AND SHENANDOAH VALLEY IN THE EVENING WITH ISENTROPIC LIFT STRENGTHENING WELL AHEAD OF LOW PRESSURE OVER THE LOWER MISSISSIPPI VALLEY. PRECIPITATION WILL EXPAND FROM SOUTHWEST TO NORTHEAST AFTER MIDNIGHT...PER GFS AND NAM ISENTROPIC/OMEGA FIELDS. GIVEN THE PREFERRED GFS TEMPERATURE PROFILES...BELIEVE P-TYPE WILL BE ALL SNOW ACROSS THE NORTHERN HALF OF OUR CWA LATE MONDAY NIGHT INTO EARLY TUESDAY. IN THIS AREA...GFS ALSO INDICATES WEAK H7-H5 VECTOR DIVERGENCE ALONG WITH FRONTOGENETIC FORCING...AND A LIGHT ACCUMULATION OF SNOW MAY RESULT. ACROSS THE SOUTHERN HALF OF OUR CWA...SURFACE/BOUNDARY LAYER TEMPERATURES WILL HAVE COOLED BELOW FREEZING. HOWEVER...A NOSE OF WARM AIR A FEW THOUSAND FEET ABOVE THE GROUND WILL MAKE IT INTO THE POTOMAC HIGHLANDS...CENTRAL VIRGINIA AND LOWER SOUTHERN MARYLAND AREA. THIS WILL ALLOW FOR ANY SNOW TO MIX WITH AND THEN CHANGE TO SLEET AND FREEZING RAIN. THIS TREND OF MIXED PRECIPITATION TILTING NORTH AND WEST WILL CONTINUE THROUGHOUT TUESDAY AS A S/SE 850 MB LOW LEVEL JET INTENSIFIES. HOWEVER...TEMPERATURES NEAR THE SURFACE WONT MOVE MUCH ON TUESDAY...AND WILL REMAIN AT OR BELOW FREEZING PER GFS (AND MET) MOS GUIDANCE. SREFS HIGHLIGHT THE HIGH LIKELIHOOD OF MIXED PRECIPITATION. THE BALDWIN ALGORITHM FAVORS MORE SLEET THAN FREEZING RAIN...YET THE CZYS ALGORITHM INDICATES MOST OF OUR CWA WOULD BE AFFECTED BY FREEZING RAIN. CONCEPTUALLY...THE CZYS SCENARIO LOOKS MORE LIKELY...AND WHEN THE DURATION OF FREEZING RAIN IS COMBINED WITH MODEL QPF...A QUARTER TO HALF INCH OF ICE COULD RESULT. AN EXCEPTION MAY BE ACROSS LOWER SOUTHERN MARYLAND...WHERE BOTH ALGORITHMS AND OPERATIONAL GFS TEMPERATURE PROFILES INDICATE A CHANGEOVER TO RAIN TUESDAY NIGHT. TAKING ALL OF INTO ACCOUNT...WILL CONTINUE WITH THE WINTER STORM WATCH FOR THIS CYCLE...BUT ACCENTUATE THE FACT THAT THERE IS INCREASED CONFIDENCE THAT THIS STORM WILL HAVE PRIMARILY MIXED PRECIPITATION...AND THAT SIGNIFICANT ICE ACCUMULATIONS MAY RESULT. WOULD SURMISE THIS WILL PAVE THE WAY FOR THE NEXT SHIFT TO ISSUE WARNINGS OR ADVISORIES AS NECESSARY. LONG TERM (WEDNESDAY THROUGH SUNDAY)... 500MB TROUGH OVER THE OHIO RIVER VALLEY AT THE BEGINNING OF THE PERIOD. THIS FEATURE AND ITS ASSOCIATED SHORTWAVE WILL MOVE OFFSHORE DURING THE DAY ON WEDNESDAY...BUT A LONGWAVE TROUGH SETS UP OVER THE EASTERN SEABOARD THROUGH FRIDAY. THE TROUGH WILL FINALLY MOVE OFFSHORE LATE FRIDAY AS A SHORTWAVE DIVES SOUTH FROM CANADA AND MOVES EAST OVER THE REGION. AT THE SURFACE...A DOUBLE BARRELED LOW HAS FORMED OFF THE MID ATLANTIC COAST WITH THE PRIMARY LOW OVER THE DELMARVA PENINSULA. THIS FEATURE WILL CONTINUE UP THE EASTERN SEABOARD FOR THE REMAINDER OF WEDNESDAY. UPSLOPE SNOWS WILL BEGIN IN THE HIGHER TERRAIN ON THE BACKSIDE OF THE DEPARTING LOW PRESSURE SYSTEM. HIGH PRESSURE BUILDS IN FROM THE WEST ON THURSDAY. THE UPSLOPE PRECIP SHOULD END EARLY ON FRIDAY AS THE RIDGING MOVES OVERHEAD. RIDGING LINGERS THROUGH SATURDAY AS A FRONTAL BOUNDARY MOVES OVER THE CENTRAL PART OF THE COUNTRY AND INTO THE LOWER MISSISSIPPI VALLEY. THIS FRONTAL BOUNDARY IS EXPECTED TO COME THROUGH THE MID ATLANTIC DURING THE LATE WEEKEND. THE MOST DIFFICULT PERIOD FOR THE LONGER TERM FORECAST WAS THE WEDNESDAY TIME FRAME. THIS WILL BE A TRANSITION PERIOD AS THE LOW PRESSURE DEPARTS AND COLDER TEMPERATURES ALOFT WILL BEGIN TO SINK SOUTHWARD ONCE AGAIN. THE HIGHER TERRAIN WILL SWITCH BACK OVER THE ALL SNOW EARLY...WHILE THE CENTRAL CWFA SWITCHES OVER FROM FREEZING RAIN TO A SNOW/SLEET MIXTURE BY MID MORNING...WITH ALL SNOW EXPECTED IN THE AFTERNOON. THE FREEZING RAIN WILL LIKELY HANG AROUND UNTIL THE MID MORNING HOURS ALONG THE NORTHERN BAY....WHILE ALL RAIN CONTINUES OVER LOWER SOUTHERN MARYLAND. EXPECT AREAS ALONG THE WESTERN SHORE TO CHANGEOVER TO ALL SNOW BY THE LATE AFTERNOON. CHANGES TO THE GRIDS WERE MOSTLY CONFINED TO THE WEDNESDAY/THURSDAY TIME FRAME. THE WEATHER/POPS WERE ADJUSTED FOR LINGERING PRECIP ALONG THE WESTERN SHORE AND FOR PTYPE. IN ADDITION...HAVE GONE BELOW MOS FOR HIGH TEMPS ON WEDNESDAY DUE TO ICE/SNOW ON THE GROUND. WINDS SHOULD ALSO BE A FACTOR...AND HAVE INCREASED ON THE BACKSIDE OF THE LOW. OTHERWISE...DIDN`T REALLY DEVIATE FROM GUIDANCE AND MADE NO CHANGES PAST THURSDAY. AVIATION... WARM ADVECTION STRATUS WHICH IS NOT BEING HANDLED WELL BY ANY OF THE MODELS CONTINUES TO BUILD SOUTH FROM PENNSYLVANIA UNDERNEATH AN INVERSION NEAR 6KFT ON THE 00Z KIAD RAOB. TREND AFTER SUNRISE SHOULD BE A HALT TO SOUTHERN PROGRESS AND PROBABLY DISSIPATION ON THE SOUTHERN FRINGE DUE TO WARMING AND DIURNAL MIXING. MEANWHILE...UPPER LEVEL MOISTURE WILL BE BUILDING DOWN AND THICKENING THROUGH THE DAY. WARM ADVECTION WILL ALLOW CONTINUED SATURATION OF THE LOWER LEVELS DURING THE EVENING...WITH AREAS OF SNOW (RAIN/SNOW NEAR KCHO) DEVELOPING AS THE EVENING PROGRESSES. MARINE... 12Z MET/MAV MOS AT THOMAS POINT INDICATE SUSTAINED WINDS 5KT OR LESS TODAY. WITH A COL IN THE SURFACE PRESSURE ACROSS THE WATERS...EXPECT LIGHT WINDS. ICE COVERAGE ACROSS THE EXTREME NORTHERN BAY IS CLOSE TO 7-8 TENTHS. THE GRADIENT WILL BEGIN TO TIGHTEN ON TUESDAY AS SURFACE LOW PRESSURE NEARS THE REGION. HAVE GONE AHEAD AND RAISED A SMALL CRAFT ADVISORY FOR STRENGTHENING NORTHEAST WINDS. HAVE MADE SOME SIGNIFICANT CHANGES TO THE WINDS AND WIND GUSTS ON THE BAY FOR WEDNESDAY AND THURSDAY. WIND GUSTS PROBABLY SAW THE MOST EDITING AS BUFKIT SOUNDINGS DO INDICATE THAT GALES GUSTS ARE LIKELY FOR WEDNESDAY. SINCE WINDS ARE TYPICALLY UNDERDONE BY THE MODELS...HAVE GONE AHEAD AND BUMPED UP THE GUST POTENTIAL TO 40 KT DURING THE DAY ON WEDNESDAY WITH 35 KT FOR WEDNESDAY NIGHT. SCA CONDITIONS ARE LIKELY TO PERSIST THROUGH FRIDAY. SINCE WEDNESDAY/THURSDAY IS STILL A LITTLE FAR OUT FOR A HEADLINE...WILL ONLY HAVE MENTION IN THE SYNOPSIS. TIDES... CURRENT TIDAL DEPARTURES ARE A HALF TO THREE QUARTERS OF A FOOT ABOVE ASTRONOMICAL PREDICTIONS. THE LUNAR CYCLE IS WANING TO A QUARTER MOON (32 PERCENT FULL). BOTH THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM AND NOAA EXTRATROPICAL STORM SURGE MODELS HAVE MISSED THE OBSERVED POSITIVE TIDAL DEPARTURES. PRESSURE GRADIENT WILL TIGHTEN AHEAD OF THE STORM SYSTEM TUESDAY...ENCOURAGING TIDAL DEPARTURES TO INCREASE FURTHER. WHILE ASTRONOMICAL TIDES ARE LOWEST FOR THE MONTH...TIDAL DEPARTURES WILL HAVE TO BE MONITORED THROUGH WEDNESDAY MORNING. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR DCZ001. MD...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR MDZ003>007-009>011-013-014-016>018-501-502. VA...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR VAZ021-025>031-036>042-050>057. WV...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR WVZ050>055-501>504. MARINE...SMALL CRAFT ADVISORY FROM 1 PM TUESDAY TO 4 AM EST WEDNESDAY FOR ANZ530>537. && $$ SHORT TERM...
AREA FORECAST DISCUSSION
NWS MIAMI FL
344 PM EST MON FEB 12 2007 ...A FEW STRONG STORMS POSSIBLE MAINLY EXTREME SE COAST AND ADJACENT WATERS TONIGHT... ...POTENTIAL COLD WEATHER EVENT LATE THIS WEEK... && .DISCUSSION... LATEST SURFACE ANALYSIS CONTINUES TO PLACE SURFACE TROUGH EXTENDING FROM THE YUCATAN PENINSULA ACROSS THE FLORIDA STRAITS JUST SOUTH OF THE KEYS NE ALONG THE GULF STREAM EAST OF THE SE FLORIDA COAST AND WEST OF THE BAHAMAS. AT THE UPPER LEVELS...LATEST AIRCRAFT DATA...GOES HIGH DENSITY WINDS...AND WATER VAPOR LOOP SHOW A NEGATIVELY TILTED S/W TROUGH JUST DUE NORTH NORTHEAST OF THE YUCATAN PENINSULA ACROSS THE CENTRAL GULF OF MEXICO AT THIS TIME WITH PLENTY OF DIVERGENCE TO ITS EAST NORTHEAST ALOFT. HOWEVER...WATER VAPOR LOOP CONTINUES TO SHOW A TREND WHEREBY THE AXIS OF THE S/W IS BECOMING LESS NEGATIVELY TILTED AND ONE WOULD EXPECT UPR LVL DIV TO DECREASE WITH THAT IF THAT TREND CONTINUES. FOR THE TIME BEING HOWEVER, THERE IS STILL ENOUGH TO SUPPORT LARGE SCALE ASCENT FOR CONVECTION...EVEN STRONG CONVECTION LIKE IT IS HAPPENING ACROSS THE KEYS. HOWEVER...WHEN LOOKING AT THE CONVECTIVE PARAMETERS ONE CAN SEE THE LIMITING FACTOR AT THIS TIME CONTINUES TO BE LIMITED CAPE (LESS THAN 1000) WITH TEMP PROFILES THAT LOOK VERY CLOSE TO MOIST ADIABATIC A RESULT OF THE LOW LEVEL MOIST AIR ADVECTION THAT HAS BEEN TAKING PLACE SINCE YESTERDAY AND THE EXTENSIVE CLOUD COVER. THE QUESTION IS WHAT HAPPENS NOW FROM THIS POINT ON. GFS40 HAS NOW COME MORE IN LINE WITH NAM12...RUC...AND LOCAL WRF SOLUTIONS. THIS MEANS TROUGH...WHICH CONTINUES TO BE QUASI STATIONARY ACROSS THE KEYS SHOULD BEGIN A GRADUAL MOVEMENT NORTH TONIGHT AND POSSIBLY BE ACROSS NORTHERN SECTIONS OF CWA POSSIBLY BY TUESDAY MORNING. THE SCENARIO STILL CARRIES PLENTY OF UNCERTAINTY GIVEN THE TREND HAS NOT SHOWN A DEFINITE START. BUT AT LEAST GUIDANCE IS CONVERGING ON THE SOLUTION. ALBEIT WEAKER THERE SHOULD BE PLENTY OF DIVERGENCE ALOFT AHEAD OF THE S/W AS IT MOVES ACROSS THE CWA TONIGHT TO SUPPORT TSTMS. HOWEVER...CAPE CONTINUES TO BE RATHER LIMITED AND IS BEST AS YOU WOULD EXPECT WHERE LOW LEVEL MOISTURE FLUX CONVERGENCE IS BEST WHICH IS ALONG EXTREME SE COAST AND THE ATLANTIC GULF STREAM WATERS. 88D TRENDS SHOWS PCPN SHIELD DRIFTING EVER SO SLOWLY NE ALONG THE BOUNDARY AND I EXPECT THIS TREND TO CONTINUE OVERNIGHT YIELDING BEST CHC OF RAIN ALONG EXTREME SE COAST AND THE ADJACENT COASTAL WATERS. THE BEST POSSIBILITY OF ANY STRONG OR EVEN SEVERE THUNDERSTORM I THINK IS CONFINED AT THIS TIME TO THAT AREA TONIGHT WHERE LOW LEVEL WIND SHEAR PROFILES AS BOUNDARY PUSHES NORTH COULD SUPPORT ROTATING STORMS. IN FACT...LOOKING AT THE W/V LOOP SEQUENCE I THINK THAT IS THE ONLY AREA WHERE THERE IS ENOUGH CAPE FOR THE UPR LVL DIVERGENCE AND ASSOCIATED LARGE SCALE ASCENT TO SUPPORT THIS POSSIBILITY ALSO...ALBEIT REMOTE. SO HAVING SAID THAT...WILL FORECAST SHOWERS WITH A CHC OF TSTMS SE COAST AND THE ADJACENT WATERS WITH RAIN CHC OR LIKELY INTERIOR AND WEST COAST AREAS WHERE MOST PCPN SHOULD CONTINUE TO BE STRATIFORM...ALTHOUGH THERE IS STILL A SLIGHT CHC OF TSTMS IN THOSE AREAS TOO. THIS SOLUTION IS CONSISTENT WITH MOST GUIDANCE NOW. AS THE EVENING EVOLVES WILL CONTINUE TO UPDATE HWO AS THREATS EVOLVE PARTICULARLY IF IT WHERE TO INCREASE BEYOND CURRENT EXPECTATIONS. FOR TOMORROW...UPR LVL S/W CURRENTLY ACROSS NW GULF BEHIND PRIMARY ONE WILL BE MOVING ACROSS THE STATE LATE IN THE DAY AND BEING IN THE WARM SECTOR...THERE WILL BE ANOTHER CHC OF BOTH SHOWERS AND TSTMS. HOWEVER...BEST SHOT AT SEVERE WEATHER AT THIS TIME LOOKS TO BE NORTH OF CWA CLOSER TO THE WARM FRONTAL BOUNDARY. AS THE SECONDARY UPR LVL S/W MOVES THROUGH LATE TOMORROW CHC OF RAIN WILL CONTINUE TO DECREASE WITH FRONT EXPECTED TO MOVES ACROSS SOUTH FLORIDA LATE WEDNESDAY. MODELS ARE ALSO SHOWING SOME ISENTROPIC INDUCED RAIN POSSIBLE THU THROUGH EARLY FRI AS THE HIGH BUILDS IN ACROSS THE AREA. THEN A CANADIAN 1040 HIGH WILL BE DROPPING SOUTH ACROSS THE CENTRAL SECTIONS OF THE CONUS WITH HIGH BUILDING IN ACROSS FL. AT THIS TIME THICKNESS VALUES FOR THE 1000-850 MB LAYER LOOKS LOW ENOUGH TO POTENTIALLY SUPPORT NEAR FREEZING TEMPS IN THE NW INTERIOR PARTICULARLY WITH THE GFS CONTINUING TO SHOW HIGH DROPPING ALL THE WAY OVER THE STATE BY FRIDAY NIGHT. NEEDLESS TO SAY THE UNCERTAINTY OF THIS KIND OF FORECAST IS HIGH AT THIS TIME...BUT THE SYNOPTIC SETTING IS THAT OF A POTENTIAL COLD WEATHER EVENT AND WILL HAVE TO WATCH CLOSELY OVER NEXT FEW DAYS. && .AVIATION... LOW CEILINGS AND PERIODS OF RAIN WILL MAINLY AFFECT THE EAST COAST TAFS DURING THE EVENING CAUSING AT LEAST MVFR CONDITIONS, HOWEVER PERIODS OF HEAVY RAIN AND PERHAPS EVEN A THUNDERSTORM WILL CAUSE EVEN LOWER CONDITIONS. THESE CONDITIONS WILL BE MORE PREVALENT AT TMB, MIA, AND FLL, BUT THESE LOWER CEILINGS AND VIS CONDITIONS WILL STILL BE POSSIBLE AT PBI AND TO A LESSER EXTENT APF. VCSH/VCTS HAS BEEN LEFT IN ALL SITES THROUGH THE PERIOD SINCE THE AREA WILL NOT LIKELY DRY OUT UNTIL TUESDAY NIGHT/WEDNESDAY MORNING. && .MARINE... OTHER THAT SCEC WIND CONDITIONS ACROSS PORTIONS OF THE OFFSHORE GULF AND ATLANTIC WATERS TONIGHT NO MAIN CONCERNS UNTIL MIDDLE TO LATE IN THE WEEK WITH NORTHERLY WINDS MOVING IN BEHIND FRONT AND SEAS BUILDING TO POSSIBLY 7 FEET OR HIGHER MAINLY ACROSS THE GULF STREAM. THE MAIN CONCERN WILL BE SHOWERS AND A FEW STORMS TONIGHT ACROSS THE ATLANTIC WATERS WITH ONE OR TWO POSSIBLY STRONG. && .FIRE WEATHER... NO CONCERNS THROUGH FORECAST PERIOD AT THIS TIME. && .HYDROLOGY... WITH SUSTAINED PERIODS OF MODERATE RAIN CURRENTLY AFFECTING METRO MIAMI DADE AND PORTIONS OF BROWARD...THERE IS THE POSSIBILITY OF MINOR STREET FLOODING IN POORLY DRAINED AREAS AT THIS TIME. BUT NO MAJOR FLOODING IS ANTICIPATED. HOWEVER...IF HEAVIER SHOWERS OR STORMS WERE TO TRAIN OVER THE SAME AREA ACROSS THE METRO AREAS...THE FLOOD POTENTIAL COULD INCREASE ACROSS THESE AREAS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 68 80 64 81 / 90 50 30 10 FORT LAUDERDALE 70 81 67 82 / 90 40 30 10 MIAMI 68 81 66 83 / 90 30 30 10 NAPLES 65 77 69 77 / 70 40 30 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ LONG TERM...52/PS SHORT TERM/AVIATION...04/AT