Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 04/01/08

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
920 PM PDT MON MAR 31 2008 ...UPDATED AVIATION DISCUSSION... .SHORT TERM (TODAY-THURSDAY)... 04Z ACARS SHOWS LITTLE IN THE WAY OF AN INVERSION AND SATELLITE IMAGERY SHOWS ONLY A FEW CLOUDS SOUTHEAST OF AVALON. STILL EDDY IS LIKELY TO DEVELOP AND WILL BRING CLOUDS UP TO SANTA MONICA. 00Z VBG SOUNDING SHOWS A MARINE LAYER DEVELOPING AND LIKELY CLOUDS WILL FORM IN PLACE WITH THE OVERNIGHT RADIATIONAL COOLING. STILL LOOKING AT UNCERTAINTY WITH THE MID WEEK STORM. SAT SHOWS IT AT 34.5 / 138 AND IT LOOKS NICELY DEVELOPED. RAIN IS LIKELY WITH THIS SYSTEM THE ONLY QUESTION IS WHEN AND HOW MUCH. 00Z MDLS OFFER NO SOLACE TO THE PROBLEM WITH NAM REMAINING SLOWER AND DRIER AND THE GFS QUICKER AND WETTER. CURRENT FORECAST FAVORS THE GFS SOLN WHICH IS SLIGHTLY PREFERRED DUE TO BETTER AGREEMENT WITH THE EC. ...FROM PREVIOUS DISCUSSION... STILL LOOKING FOR A DECENT SYSTEM FOR THIS TIME OF THE YEAR AFFECTING THE AREA ON WED...AS A 552 DM LOW MOVES ASHORE. ALTHOUGH THE SYSTEM IS CLEARLY VISIBLE ON THE SAT AND CURRENTLY SITS FAIRLY CLOSE THE THE CA COAST...TIMING CONCERNS STILL EXIST...AS MODELS CONTINUE TO SUBTLY SLOW THIS SYSTEM DOWN. WEIGHTED FORECAST MORE ON THE GFS SOLUTION...EVEN THOUGH IT IS AN OUTLIER FROM THE OTHER MODELS. THE GFS HAS BEEN THE MOST RUN TO RUN CONSISTENT AND INITIALIZED WELL WITH THE LATEST SAT IMAGES. ADJUSTED TIMING OF POPS...WITH LIKELY CATEGORIES STILL FOR THE WHOLE AREA...BUT DELAYED BY ABOUT 6 HOURS FROM PREVIOUS FORECAST. BULK OF RAIN FOR NORTH OF POINT CONCEPTION LOOKS TO BE ON WED AFTERNOON...THEN WED EVENING TO THE SOUTH. AMOUNTS WERE TRIMMED BACK A BIT AS WELL DUE TO THE QUICK MOVING NATURE OF THIS STORM AND THE LESS FAVORABLE SOUTHERLY TRACK OF THE STORM. LOOKING FOR A QUARTER TO ABOUT A HALF OF AN INCH FOR THE COASTS AND VALLEYS...AND AROUND ONE HALF TO ABOUT AN INCH FOR THE MTNS AND FOOTHILLS. THERE SHOULD BE A DECENT AMOUNT OF COLD AIR ALOFT WITH 500MB TEMPS AROUND -20C. THIS SHOULD HELP SNOW LEVELS TO DROP TO GENERALLY AROUND 6500 FEET...LOWERING TO JUST UNDER 6000 FEET BY THU MORNING...WHEN A FEW SHOWERS WILL PROBABLY BE HANGING AROUND LA AND VTU COUNTY. CURRENTLY EXPECTING MODERATE SNOW ACCUMULATIONS ABOVE 7000 FEET...WITH AROUND 10 INCHES POSSIBLE. MIN TEMPS WILL BE UP A BIT ON WED AND THURS THANKS TO THE INCREASED MOISTURE...BUT MAX TEMPS WILL DIP ABOUT 2 TO 6 DEGREES...THOUGH LA/VTU CO WILL SEE THE SMALLEST CHANGE WITH THE LATER ONSET OF THE SYSTEM. WINDS DO NOT LOOK LIKE A BIG CONCERN AT THIS POINT. TEMPS SHOULD REBOUND QUITE NICELY ON THURS AS THINGS CLEAR OUT BEHIND THIS SYSTEM...ESPECIALLY TO THE NORTH AS A RIDGE BEGINS TO NUDGE IN. .LONG TERM (FRIDAY-MONDAY)... TEMPS WILL BE ON THE RISE FRI AND SAT AS A NICE RIDGE BUILDS ALOFT AND LIGHT OFFSHORE FLOW FORMS THANKS TO THE WED SYSTEM MOVING INLAND. LOOKING FOR TEMPS TO GO NEAR AND ABOVE NORMAL BY SAT...WITH SOME VALLEYS GETTING INTO THE LOW 80S. MODELS CONTINUE TO SHOW A CLOSED LOW CUTTING OFF FROM THE JET STREAM OVER THE WEEKEND AND WOBBLING AROUND WELL OFF THE COAST. TO NO SURPRISE...MANY DIFFERING SOLUTIONS EXIST AS TO WHAT THIS LOW WILL DO. THE GFS AND ECMWF HINT AT TRYING TO PUSH IT TOWARD SHORE ON SUN AND MON...WITH THE THE ECMWF TRAILING BEHIND THE GFS BY AT LEAST 12 HRS. THE MORAL HERE IS THAT IT IS WAY TOO EARLY TO TRY TO PEG THIS SYSTEM...SO LEFT THE SLIGHT CHANCE RIDING FOR SUN AND SUN NIGHT...THOUGH THAT WILL LIKELY CHANGE OVER THE NEXT COUPLE OF DAYS. IF THE MODELS ARE CORRECT IN PUSHING IT TOWARD SHORE ON SUN AND MON...REGARDLESS OF WHERE IT IS EXACTLY...IT SHOULD HELP TO SQUEEZE THE RIDGE ALOFT TO THE SOUTH AND COOL THINGS OFF FOR THE BEGINNING OF NEXT WEEK. && .AVIATION... 01/0000Z WEAK MARINE LAYER AT 1300 FEET. CLEAR SKIES AT THE MOMENT. A WEAK EDDY IS FORECAST TONIGHT. MARINE CLOUD FORMATION IS NOT CERTAIN. BEST CHANCES WILL BE KSMX...KLAX...KLGB. .KLAX...LOW CONFIDENCE IN MARINE CLOUD FORECAST BOTH IN TIMING AND HGT. CIGS COULD BE AS LOW AS 015 OR CIGS MIGHT NOT ARRIVE AT ALL. VIS FORECAST LOOKS GOOD. .KBUR...GOOD CONFIDENCE IN FORECAST. A 20 PERCENT CHANCE OF IFR CIGS FROM 14Z-17Z. .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...KITTELL/ASR AVIATION...ASR WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
500 PM PDT MON MAR 31 2008 ...UPDATED AVIATION DISCUSSION... .SHORT TERM (TODAY-THURSDAY)... 04Z ACARS SHOWS LITTLE IN THE WAY OF AN INVERSION AND SATELLITE IMAGERY SHOWS ONLY A FEW CLOUDS SOUTHEAST OF AVALON. STILL EDDY IS LIKELY TO DEVELOP AND WILL BRING CLOUDS UP TO SANTA MONICA. 00Z VBG SOUNDING SHOWS A MARINE LAYER DEVELOPING AND LIKELY CLOUDS WILL FORM IN PLACE WITH THE OVERNIGHT RADIATIONAL COOLING. STILL LOOKING AT UNCERTAINTY WITH THE MID WEEK STORM. SAT SHOWS IT AT 34.5 / 138 AND IT LOOKS NICELY DEVELOPED. RAIN IS LIKELY WITH THIS SYSTEM THE ONLY QUESTION IS WHEN AND HOW MUCH. 00Z MDLS OFFER NO SOLACE TO THE PROBLEM WITH NAM REMAINING SLOWER AND DRIER AND THE GFS QUICKER AND WETTER. CURRENT FORECAST FAVORS THE GFS SOLN WHICH IS SLIGHTLY PREFERRED DUE TO BETTER AGREEMENT WITH THE EC. ...FROM PREVIOUS DISCUSSION... STILL LOOKING FOR A DECENT SYSTEM FOR THIS TIME OF THE YEAR AFFECTING THE AREA ON WED...AS A 552 DM LOW MOVES ASHORE. ALTHOUGH THE SYSTEM IS CLEARLY VISIBLE ON THE SAT AND CURRENTLY SITS FAIRLY CLOSE THE THE CA COAST...TIMING CONCERNS STILL EXIST...AS MODELS CONTINUE TO SUBTLY SLOW THIS SYSTEM DOWN. WEIGHTED FORECAST MORE ON THE GFS SOLUTION...EVEN THOUGH IT IS AN OUTLIER FROM THE OTHER MODELS. THE GFS HAS BEEN THE MOST RUN TO RUN CONSISTENT AND INITIALIZED WELL WITH THE LATEST SAT IMAGES. ADJUSTED TIMING OF POPS...WITH LIKELY CATEGORIES STILL FOR THE WHOLE AREA...BUT DELAYED BY ABOUT 6 HOURS FROM PREVIOUS FORECAST. BULK OF RAIN FOR NORTH OF POINT CONCEPTION LOOKS TO BE ON WED AFTERNOON...THEN WED EVENING TO THE SOUTH. AMOUNTS WERE TRIMMED BACK A BIT AS WELL DUE TO THE QUICK MOVING NATURE OF THIS STORM AND THE LESS FAVORABLE SOUTHERLY TRACK OF THE STORM. LOOKING FOR A QUARTER TO ABOUT A HALF OF AN INCH FOR THE COASTS AND VALLEYS...AND AROUND ONE HALF TO ABOUT AN INCH FOR THE MTNS AND FOOTHILLS. THERE SHOULD BE A DECENT AMOUNT OF COLD AIR ALOFT WITH 500MB TEMPS AROUND -20C. THIS SHOULD HELP SNOW LEVELS TO DROP TO GENERALLY AROUND 6500 FEET...LOWERING TO JUST UNDER 6000 FEET BY THU MORNING...WHEN A FEW SHOWERS WILL PROBABLY BE HANGING AROUND LA AND VTU COUNTY. CURRENTLY EXPECTING MODERATE SNOW ACCUMULATIONS ABOVE 7000 FEET...WITH AROUND 10 INCHES POSSIBLE. MIN TEMPS WILL BE UP A BIT ON WED AND THURS THANKS TO THE INCREASED MOISTURE...BUT MAX TEMPS WILL DIP ABOUT 2 TO 6 DEGREES...THOUGH LA/VTU CO WILL SEE THE SMALLEST CHANGE WITH THE LATER ONSET OF THE SYSTEM. WINDS DO NOT LOOK LIKE A BIG CONCERN AT THIS POINT. TEMPS SHOULD REBOUND QUITE NICELY ON THURS AS THINGS CLEAR OUT BEHIND THIS SYSTEM...ESPECIALLY TO THE NORTH AS A RIDGE BEGINS TO NUDGE IN. .LONG TERM (FRIDAY-MONDAY)... TEMPS WILL BE ON THE RISE FRI AND SAT AS A NICE RIDGE BUILDS ALOFT AND LIGHT OFFSHORE FLOW FORMS THANKS TO THE WED SYSTEM MOVING INLAND. LOOKING FOR TEMPS TO GO NEAR AND ABOVE NORMAL BY SAT...WITH SOME VALLEYS GETTING INTO THE LOW 80S. MODELS CONTINUE TO SHOW A CLOSED LOW CUTTING OFF FROM THE JET STREAM OVER THE WEEKEND AND WOBBLING AROUND WELL OFF THE COAST. TO NO SURPRISE...MANY DIFFERING SOLUTIONS EXIST AS TO WHAT THIS LOW WILL DO. THE GFS AND ECMWF HINT AT TRYING TO PUSH IT TOWARD SHORE ON SUN AND MON...WITH THE THE ECMWF TRAILING BEHIND THE GFS BY AT LEAST 12 HRS. THE MORAL HERE IS THAT IT IS WAY TOO EARLY TO TRY TO PEG THIS SYSTEM...SO LEFT THE SLIGHT CHANCE RIDING FOR SUN AND SUN NIGHT...THOUGH THAT WILL LIKELY CHANGE OVER THE NEXT COUPLE OF DAYS. IF THE MODELS ARE CORRECT IN PUSHING IT TOWARD SHORE ON SUN AND MON...REGARDLESS OF WHERE IT IS EXACTLY...IT SHOULD HELP TO SQUEEZE THE RIDGE ALOFT TO THE SOUTH AND COOL THINGS OFF FOR THE BEGINNING OF NEXT WEEK. && .AVIATION... 01/0000Z WEAK MARINE LAYER AT 1300 FEET. CLEAR SKIES AT THE MOMENT. A WEAK EDDY IS FORECAST TONIGHT. MARINE CLOUD FORMATION IS NOT CERTAIN. BEST CHANCES WILL BE KSMX...KLAX...KLGB. .KLAX...LOW CONFIDENCE IN MARINE CLOUD FORECAST BOTH IN TIMING AND HGT. CIGS COULD BE AS LOW AS 015 OR CIGS MIGHT NOT ARRIVE AT ALL. VIS FORECAST LOOKS GOOD. .KBUR...GOOD CONFIDENCE IN FORECAST. A 20 PERCENT CHANCE OF IFR CIGS FROM 14Z-17Z. .LOX WATCHES/WARNINGS/ADVISORIES... SMALL CRAFT ADVISORY (SEE LAXCWFLOX). && $$ PUBLIC...KITTELL/ASR AVIATION...ASR WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
930 PM PDT MON MAR 31 2008 .SYNOPSIS...HIGH PRESSURE WILL KEEP THE WEATHER FAIR THROUGH TUESDAY EXCEPT FOR LOW CLOUDS AND FOG WEST OF THE MOUNTAINS DURING THE NIGHTS AND MORNINGS. A LOW PRESSURE SYSTEM IS EXPECTED TO BRING SHOWERS LATE WEDNESDAY. FAIR DURING THE SECOND HALF OF THE WEEK WITH DRY NORTHWEST FLOW ALOFT. && .DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES. .SHORT TERM (TONIGHT-THU)...SKIES WERE CLEAR THIS EVENING EXCEPT FOR PATCHES OF STRATUS NEAR THE COAST AND A FEW HIGH CLOUDS. THE 00Z NKX SOUNDING HAD AN INVERSION BASED NEAR 3400 FT BUT THE LATEST ACARS SOUNDINGS SHOWED A LOWER INVERSION. WSW WINDS ALOFT. WEAKENING ONSHORE GRADIENTS WITH ABOUT 5 MB SAN-IPL. SUBSIDENCE WILL CAUSE A LOWERING MARINE LAYER UNDER A STRONGER INVERSION TONIGHT. ONSHORE FLOW WILL BRING COASTAL LOW CLOUDS AND FOG TONIGHT...EXTENDING INTO MOST SAN DIEGO INLAND VALLEY AND WRN INLAND EMPIRE LATE. OTHERWISE...FAIR AND A LITTLE WARMER TUE UNDER WEAK HIGH PRESSURE. AN UPPER LOW OFF THE NRN CA COAST WILL DROP S TUE AND EARLY WED AND THEN MOVE E ACROSS SRN CA LATE WED. THIS WILL MAKE SHOWERS LIKELY IN MOST AREAS WED NIGHT. PRELIMINARY RAINFALL ESTIMATES ARE FOR LESS THAN HALF AN INCH W OF THE MOUNTAINS WITH ISOLATED ONE INCH AMOUNTS POSSIBLE ON W FACING MOUNTAIN SLOPES. DESERTS WILL HAVE A CHANCE OF GETTING A FEW HUNDREDTH OF AN INCH OF RAIN. THE SNOW LEVEL WILL LOWER TO NEAR 6000 FT AND WINDS WILL INCREASE...ESPECIALLY IN THE MOUNTAINS AND DESERTS. HOWEVER...WINDS ARE EXPECTED TO REMAIN BELOW ADVISORY STRENGTH WITH GUSTS TO AROUND 40 MPH. A CHANCE OF SHOWERS WILL LINGER INTO THU MORNING...ENDING DURING THE AFTERNOON AS THE LOW MOVES E. A LITTLE COOLER WED THEN WARMER THU. && .LONG TERM (FRI-MON)...MODELS CONTINUE TO BE IN POOR AGREEMENT DURING THE EXTENDED PERIOD BUT GENERALLY INDICATE RIDGING FRI AND SAT FOR FAIR EXCEPT FOR MARINE LAYER CLOUDS AND VARIABLE HIGH CLOUDINESS. WARMER FRI AND SAT. THE HIGH SHOULD WEAKEN AND EVENTUALLY GET REPLACED BY A TROUGH SUN AND MON FOR MORE CLOUDS AND COOLING. && .AVIATION... 010240Z...SKIES WERE CLEAR WITH VFR CONDITIONS AT 02Z. BUT BASED ON SOUNDING DATA...STRATUS BASES SHOULD FORM BETWEEN FL020 AND FL030 SOMETIME TONIGHT AND COULD LOWER TO JUST BELOW FL020 TOWARD DAWN. ONSET OF CIGS IS MORE PROBLEMATIC...BUT EXPECTED AT ALL AIRPORTS WEST OF THE MOUNTAINS BETWEEN 06Z AND 12Z. TOPS WILL BE BELOW FL035. AREAS OF MVFR VIS WILL BE LIKELY BETWEEN 06Z AND 15Z AS WELL WITH LOCAL IFR VIS/CIGS FAR INLAND. EXPECT THE MARINE CLOUDS TO MIX OUT BETWEEN 16Z AND 19Z ON TUE. ABOVE THE MARINE LAYER EXPECT VFR CONDITIONS AND LIGHT WIND THROUGH TUE. && .SGX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...DA AVIATION...JAD
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
900 AM PDT SUN MAR 30 2008 .SYNOPSIS... WEAK UPPER LEVEL LOW PRESSURE WILL BRING CLOUDS AND AREAS OF LIGHT RAIN ALONG AND WEST OF THE MOUNTAINS THIS MORNING WITH GUSTY WINDS IN THE MOUNTAINS AND DESERTS THROUGH THIS EVENING. HIGH PRESSURE WILL BRING FAIR WEATHER MONDAY AND TUESDAY EXCEPT FOR SOME COASTAL LOW CLOUDS AND FOG IN THE NIGHTS AND MORNINGS. ANOTHER LOW PRESSURE SYSTEM WEDNESDAY COULD BRING GREATER RAINFALL AMOUNTS. FAIR WEATHER IS EXPECTED THURSDAY AND FRIDAY UNDER WEAK HIGH PRESSURE. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... THE PRECIP HAS TAPERED OFF THIS MORNING SUCH AS IT WAS AND VERY LITTLE IF ANY ADDITIONAL RAINFALL IS EXPECTED. THE MARINE LAYER HAS DEEPENED AND THE LOWER CLOUDS HAVE CLIMBED UP THE MTN SLOPES TO ABOUT 6000 FEET. A LEGITIMATE FRONT IS SHOWN MOVING THROUGH CENTRAL CA THIS MORNING WITH RAIN HEADING INTO LA COUNTY...BUT THIS APPEARS VERY LIGHT. EVEN SO...THERE MAY BE ANOTHER ROUND OF LIGHT SHOWERS IN ORANGE AND SBD COUNTIES DURING THE LATE MORNING. PARTIAL CLEARING IS EXPECTED THIS AFTERNOON STARTING AT THE COAST. IN THE HIGHER MTNS AND DESERTS IT WILL BE PARTLY CLOUDY TO MOSTLY SUNNY TODAY...BUT WINDS WILL INCREASE IN THE MTNS AND DESERTS AND CONTINUE THROUGH THE EVENING. THE STRONGEST WINDS WILL BE LATE THIS AFTERNOON ALONG THE MTN/DESERT TRANSITION ZONE. AREAS OF LOW CLOUDS WILL CONTINUE IN THE COASTAL BASIN TONIGHT AS THE MARINE INVERSION REDEVELOPS AT A LOWER LEVEL. HIGH PRESSURE WILL BRING FAIR AND DRY WEATHER MON AND TUE...WITH SOME NOCTURNAL CLOUDS NEAR THE COAST. ON WED ANOTHER SHORTWAVE TROUGH WILL ARRIVE IN SOCAL. THIS ONE HAS A DEEPER AND MORE SATURATED MOISTURE PROFILE THAN THE SYSTEM TODAY AND GREATER RAINFALL IS EXPECTED...BUT IT WILL NOT BE VERY HEAVY. HIGH PRESSURE RETURNS THU AND FRI. THESE DAYS LOOK JUST LIKE MON AND TUE...A COUPLE DAYS OF FAIR DRY WEATHER IN BETWEEN SYSTEMS...BUT WITH SOME NOCTURNAL LOW CLOUDS NEAR THE COAST. ANOTHER LOW PRESSURE SYSTEM ADVERTISED NEXT WEEKEND SOMETIME HAS BEEN TRENDING TO OCCUR LATER BY RECENT RUNS OF EXTENDED MODELS. FOR NOW THE FRAGILE BEST GUESS IS TO GET SOME RAIN LATE SUN OR MON. && .AVIATION... 301400Z...MARINE LAYER DEPTH THIS MORNING WAS AROUND 4500 FEET BASED ON MDCRS SOUNDINGS. MULTIPLE LAYERS OF BROKEN TO OVERCAST STRATOCU WITH BASES RANGING BETWEEN 1500 AND 2500 FEET MSL WILL CONTINUE OVER THE AREA THROUGH THE THIS EVENING. VISIBILITIES MOSTLY 6 MILES OR BETTER BUT LOCALLY 3 TO 5 MILES IN LIGHT DRIZZLE OR LIGHT RAIN. COASTAL SLOPES OF THE MOUNTAINS WILL REMAIN MOSTLY OBSCURED IN CLOUDS AND PRECIPITATION THROUGH TONIGHT. ABOVE THE MARINE LAYER INCLUDING THE DESERT AREAS...MOSTLY CLEAR SKY WITH UNRESTRICTED VISIBILITIES WILL CONTINUE THROUGH MONDAY. STRONG ONSHORE FLOW WILL PRODUCE GUSTY WEST TO NORTHWEST WINDS ACROSS THE MOUNTAINS AND THROUGH THE BANNING PASS AND PORTIONS OF THE DESERTS THROUGH THIS EVENING. THIS WILL CAUSE AREAS OF BLOWING DUST...STRONG UP AND DOWNDRAFTS...AND SOME MOUNTAIN WAVE/ROTOR ACTIVITY VICINITY KPSP. && .MARINE... INCREASING ONSHORE FLOW WILL RESULT IN 20-25 KT WINDS BY THIS AFTERNOON AND EVENING OVER THE OUTER COASTAL WATERS WITH GUSTS TO NEAR 30 KT AT TIMES. THE STRONGEST WINDS AND ROUGHEST SEAS WILL OCCUR NEAR SAN CLEMENTE ISLAND. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE OUTER COASTAL WATERS FROM 2 PM THIS AFTERNOON THROUGH 10 PM TONIGHT. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...WIND ADVISORY FROM NOON TODAY TO MIDNIGHT PDT TONIGHT FOR APPLE AND LUCERNE VALLEYS-COACHELLA VALLEY-RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY DESERTS-SAN DIEGO COUNTY MOUNTAINS. PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS EVENING FOR WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND. && $$ PUBLIC...MM AVIATION/MARINE...HORTON
AREA FORECAST DISCUSSION
NWS UPTON NY
1056 PM EDT MON MAR 31 2008 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO SLIDE EAST THIS AFTERNOON. A WARM FRONT WILL PUSH NORTH OF THE AREA TONIGHT. A COLD FRONT SWEEPS ACROSS THE AREA TUESDAY NIGHT...FOLLOWED BY HIGH PRESSURE FOR MID WEEK. ANOTHER STORM SYSTEM APPROACHES LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... WARM FRONT APPEARS TO HAVE JUMPED THROUGH THE ENTIRE CWA WITH THE EXCEPTION OF ORANGE...PUTNAM AND W PASSAIC COUNTIES WHERE TEMPS ARE STILL IN THE LOWER TO MID 40S. TRENDS OVER THE LAST FEW HOURS WOULD INDICATE IT PUSHING NORTH HERE AS WELL OVER THE NEXT FEW HOURS WITH A 40 TO 50 KT SOUTHERLY JET AROUND THE 1K FT MARK TO HELP IT. ANOTHER BATCH OF SCT LIGHT RAIN MOVING INTO NYC WILL CONTINUE IN A NE DIRECTION ACROSS THE REMAINDER OF THE AREA THIS EVENING. AND WITH YET MORE OVER VIRGINIA...KEPT LIKELYS IN THE FORECAST OVERNIGHT BUT LOW QPF. MAIN ADJUSTMENT TO GRIDS THIS EVE...WAS FOR HOURLY TEMPS AND DEWS WITH THE WARMER/MOISTER AIR MOVING IN FASTER THAN ORIGINALLY THOUGHT. TEMPS MAY CONTINUE TO RISE A FEW DEGREES THROUGH THE EARLY MORNING...BUT THEN SHOULD HOLD STEADY IN THE LOWER TO MID 50S...WITH WARMEST READINGS AWAY FROM THE IMMEDIATE COAST WHERE A S-SW FLOW IS ADVECTING IN COOLER AIR OFF THE WATERS. THE POTENTIAL EXISTS FOR DENSE FOG TO DEVELOP OVERNIGHT AS WELL WITH WARMER AIR MOVING OVER THE COOLER WATERS. NOT CONFIDENT ENOUGH TO PUT UP DENSE FOG ADVSY BUT WILL NEED TO MONITOR CONDITIONS OVERNIGHT. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... STRONG 70KT LL JET SETS UP ACROSS NYC AND POINTS EAST TUES AM. BUFKIT SOUNDINGS SUGGEST THAT WIND ADVISORY STRENGTH WINDS MOST LIKELY AT THE SURFACE AFTER 18Z TUES. THUS...HAVE HELD OFF ON ISSUING A WIND ADVISORY TO ALLOW THE NIGHT SHIFT TO FURTHER ANALYZE. THE OTHER ISSUE IS HOW FAR WEST TO BRING THE ADVISORY...AS IT APPEARS THERE WILL NOT BE A CLEAR DIFFERENTIATION BETWEEN ADV WINDS AND WEAKER WINDS TO THE WETS. AT THIS TIME IT APPEARS A GOOD DEMARCATION WILL BE THE HUDSON RIVER VALLEY...WITH NYC IN THE ADVISORY. WILL ALSO BE LOOKING AT VERY WARM TEMPS WITH THE LL JET DELIVERING 60-65 DEG AIR TO AREAS WITHOUT A MARINE INFLUENCE. ALL THIS WARMTH AND DYNAMICAL FORCING COULD ALSO RESULT IN POTENT CONVECTION...ESPECIALLY IF A SQUALL LINE DEVELOPS. BEST CHANCES FOR DAMAGING WINDS WILL BE FROM NYC NORTH AND WEST...AGAIN AWAY FROM THE COOLER MARINE INFLUENCE. REGARDLESS OF WHETHER THERE IS A PREFRONTAL TROUGH...THE FRONT IS EXPECTED TO WONDER THROUGH IN THE EVENING HOURS...WITH A PERIOD OF POSSIBLE ADVISORY WINDS IN NW FLOW INTO EARLY WED MORNING. STRONG HIGH PRESSURE BUILDS IN WED NIGHT WITH QUIET WEATHER ON THE HORIZON. && .LONG TERM /THURSDAY THROUGH MONDAY/... FORECAST FOR THE PERIOD ON TRACK WITH THE CURRENT FORECAST. ONLY CHANGE WAS TO GO WITH LIKELY PROBABILITIES LATER THURSDAY NIGHT INTO FRIDAY AS CONSISTENCY REMAINS AND BEST CHANCES WILL BE IN THAT TIME FRAME. PRECIPITATION TYPES STILL AN ISSUE LATE THURSDAY NIGHT INTO FRIDAY MORNING ACROSS THE NORTHERN TIER AS AN EASTERLY FLOW DEVELOPS WITH HIGH PRESSURE MOVING EAST OF THE AREA...POSSIBLY KEEPING COLD AIR IN THE REGION. WILL BE A MARGINAL EVENT SO WENT WITH A MIX OF RAIN AND SNOW. MAINLY FOLLOWED HPC GUIDANCE ALONG WITH A BLEND OF SOME GFS IN THE EARLIER PERIODS AS MODEL DIFFERENCES ACROSS THE EASTERN UNITED STATES NOT YET SIGNIFICANT. DIFFERENCES MORE APPARENT AFTER THE PASSAGE OF THE COLD FRONT FRIDAY NIGHT...AS GFS DEVELOPS LOW OVER THE SOUTHEASTERN STATES SATURDAY ON THE STALLED FRONTAL BOUNDARY. KEPT SLIGHT CHANCE PROBABILITIES SATURDAY THROUGH MONDAY WITH THE UNCERTAINTY. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... TOUGH FORECAST THIS EVENING. WARM FRONT APPEARS TO HAVE JUMPED THROUGH ALL TAF TERMINALS WITH A RETURN TO VFR CONDITIONS EXCEPT AT KSWF...WHERE COLD AIR DAMMING HAS HAMPERED ITS PROGRESS AND IFR CONDITIONS REMAIN. HOWEVER TRENDS OVER THE LAST 2 HOURS ARE INDICATING THAT IT IS GETTING CLOSE. ADVECTION FOG AND STRATUS IS EXPECTED TO DEVELOP TONIGHT AS DEWPOINTS RISE TO AROUND THE 50 DEGREE MARK OVER WATER TEMPS IN THE MID 40S UNDER A SOUTHERLY LOW LEVEL FLOW. NO HINT OF IT AS OF 00Z...BUT THINK BY MIDNIGHT WE SHOULD SEE SOME INDICATION WITH CONDITIONS DROPPING BACK TO IFR/LIFR INTO EARLY TUE MORNING. SOME IMPROVEMENT TO MVFR IS POSSIBLE AFTER 14Z-15Z AT NYC AREA TERMINALS AS WARMER AIR MOVES IN FROM THE SOUTHWEST. S-SW WINDS SHOULD INCREASE DURING THE MORNING TO 15-20 KT WITH GUSTS 20-25 KT AS WELL. KOKX 00Z BALLOON ALREADY INDICATED 53KT WINDS AT 1300FT SO HAVE INCLUDED LLWS IN THE TAFS RIGHT OFF THE BAT FOR KISP...KBDR AND KGON. MODELS NOT HANDLING THE STRENGTH OF THE LLJ WELL AND DID NOT INDICATE LLWS BEING AN ISSUE UNTIL TUE MORNING. ACARS SOUNDING OUT OF KLGA AT 0030Z SHOWS 50KT WINDS ABOVE 2K FT WITH FORECAST SOUNDINGS INDICATING ONLY A GRADUAL INCREASE IN SPEED WITH HEIGHT OVERNIGHT SO HAVE NOT INCLUDED IT AT THE MAJOR TERMINALS. MOST TERMINALS SHOULD SEE IMPROVEMENT TO HIGH-END MVFR OR EVEN VFR DURING TUE AFTERNOON...BUT WITH GUSTY S-SW WINDS CONTINUING AHEAD OF AN APPROACHING COLD FRONT. THE COLD FRONT COULD BE PRECEDED BY A SQUALL LINE WITH BRIEF IFR...THUNDER AND GUSTY WINDS LATE TUE AFTERNOON INTO TUE EVENING BUT ITS TOO EARLY TO INCLUDE ATTM. OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY... CONDITIONS WILL IMPROVE BACK TO VFR BEHIND THE FROPA TUE EVE UNDER A GUSTY W-NW FLOW. SUB-VFR CONDITIONS IN RAIN...POSSIBLY MIXED WITH SNOW AT THE ONSET NORTH OF THE NYC TERMINALS...ARE ALSO LIKELY LATE THU NIGHT INTO FRI NIGHT. ANOTHER SYSTEM APPROACHES FROM THE SE STATES ON SAT WITH SUB-VFR CONDITIONS POSSIBLE AGAIN. && .MARINE... NO MAJOR CHANGES TO THE MARINE FORECAST. ONLY ADJUSTED SEAS ON THE SOUND...HARBOR AND BACK BAYS A BIT IN THE SHORT TERM. SEAS ON THE OCEAN HAVE BUILT TO SCA LEVELS AND CURRENT TIMING TO ADD REMAINING ZONES LOOKS REASONABLE. LOW END GALE FORCE WINDS ARE POSSIBLE TUESDAY AFTERNOON...BUT PRIMARILY IF CONVECTION DEVELOPS OR MOVES OUT OVER THE WATERS. OTHERWISE IT WILL BE HARD TO MIX GALE FORCE WINDS TO THE SURFACE. FROPA EXPECTED TUESDAY EVENING...WITH WINDS FLIPPING AROUND TO NW AND REMAINING STRONG INTO WED AM. THE CURRENT SCA GOES UNTIL 10Z...BUT MAY NEED TO BE EXTENDED FOR SEAS. HIGH PRESSURE OVER THE FORECAST WATERS WEDNESDAY NIGHT AND THURSDAY WILL KEEP THE AREA DRY AND WINDS AND SEAS BELOW ADVISORY LEVELS. A WARM FRONT APPROACHES THURSDAY NIGHT AND MAY LIFT THROUGH FRIDAY. PRECIPITATION BECOMES LIKELY THURSDAY NIGHT WITH REDUCED VISIBILITIES IN THE RAIN AND FOG. THE ASSOCIATED LOW WILL MOVE WEST AND NORTH...THEN NORTHEAST OF THE WATERS THURSDAY NIGHT INTO FRIDAY. A COLD FRONT WITH THE LOW MOVES THROUGH FRIDAY NIGHT. THE COLD FRONT STALLS EAST OF THE WATERS SATURDAY AND A WAVE DEVELOPS OVER THE SOUTHEASTERN STATES LATER SATURDAY. AN INCREASING SOUTHERLY FLOW AHEAD OF THE LOW FRIDAY WILL BUILD SEAS ON THE OCEAN TO SMALL CRAFT LEVELS. SEAS CONTINUE TO BUILD INTO FRIDAY NIGHT TO ABOUT 7 FEET. WITH THE PASSAGE OF THE COLD FRONT FRIDAY NIGHT WINDS SHIFT TO THE WEST AND SEAS WILL BEGIN TO SUBSIDE SATURDAY INTO SATURDAY NIGHT. && .HYDROLOGY... 1/4 TO 3/4 INCH QPF POSSIBLE THROUGH TUESDAY NIGHT WITH FRONTAL SYSTEM. HIGHEST QPF NW OF NYC AND IN THUNDERSTORMS TUESDAY. SHOULD NOT HAVE MUCH IF ANY IMPACT ON AREA RIVERS AND STREAMS WITH LONG DURATION EVENT. && .TIDES/COASTAL FLOODING... STRENGTHENING SOUTHERLY WINDS NOT EXPECTED TO PRODUCE SIGNIFICANT COASTAL FLOODING...BUT MAY RESULT IN HIGHER TIDAL RANGES TUESDAY AND TUESDAY NIGHT. BLOWOUT TIDES ALSO NOT EXPECTED TO HAVE SIGNIFICANT IMPACT. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM TUESDAY TO 6 AM EDT WEDNESDAY FOR ANZ330-335-338-340-345. SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ350-353- 355. && $$
AREA FORECAST DISCUSSION
NWS UPTON NY
929 PM EDT MON MAR 31 2008 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO SLIDE EAST THIS AFTERNOON. A WARM FRONT WILL PUSH NORTH OF THE AREA TONIGHT. A COLD FRONT SWEEPS ACROSS THE AREA TUESDAY NIGHT...FOLLOWED BY HIGH PRESSURE FOR MID WEEK. ANOTHER STORM SYSTEM APPROACHES LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... WARM FRONT APPEARS TO HAVE JUMPED THROUGH THE ENTIRE CWA WITH THE EXCEPTION OF NORTHERN ORANGE AND PUTNAM COUNTIES WHERE TEMPS ARE STILL IN THE LOWER TO MID 40S. TRENDS OVER THE LAST FEW HOURS WOULD INDICATE IT PUSHING NORTH HERE AS WELL OVER THE NEXT FEW HOURS WITH A 40 TO 50 KT SOUTHERLY JET AROUND THE 1K FT MARK TO HELP IT. ANOTHER BATCH OF LIGHT RAIN MOVING INTO NYC WILL CONTINUE IN A NE DIRECTION ACROSS THE REMAINDER OF THE AREA THIS EVENING. ALTHOUGH THE HEAVIEST RAIN WILL REMAIN NORTH OF THE CWA...KEPT LIKELYS IN THE FORECAST FOR TONIGHT BUT LOW QPF. TEMPS EXPECTED TO REMAIN STEADY FOR A FEW HOURS THIS EVENING THEN RISE INTO THE 50S AS STRONGER SOUTHERLY FLOW DEVELOPS. 12Z MODELS IN GOOD AGREEMENT ON TEMP TRENDS...BUT STAYED CLOSER TO MAV NUMBERS WHICH WERE CLOSER TO REALITY WITH RESPECT TO CURRENT TEMPS. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... STRONG 70KT LL JET SETS UP ACROSS NYC AND POINTS EAST TUES AM. BUFKIT SOUNDINGS SUGGEST THAT WIND ADVISORY STRENGTH WINDS MOST LIKELY AT THE SURFACE AFTER 18Z TUES. THUS...HAVE HELD OFF ON ISSUING A WIND ADVISORY TO ALLOW THE NIGHT SHIFT TO FURTHER ANALYZE. THE OTHER ISSUE IS HOW FAR WEST TO BRING THE ADVISORY...AS IT APPEARS THERE WILL NOT BE A CLEAR DIFFERENTIATION BETWEEN ADV WINDS AND WEAKER WINDS TO THE WETS. AT THIS TIME IT APPEARS A GOOD DEMARCATION WILL BE THE HUDSON RIVER VALLEY...WITH NYC IN THE ADVISORY. WILL ALSO BE LOOKING AT VERY WARM TEMPS WITH THE LL JET DELIVERING 60-65 DEG AIR TO AREAS WITHOUT A MARINE INFLUENCE. ALL THIS WARMTH AND DYNAMICAL FORCING COULD ALSO RESULT IN POTENT CONVECTION...ESPECIALLY IF A SQUALL LINE DEVELOPS. BEST CHANCES FOR DAMAGING WINDS WILL BE FROM NYC NORTH AND WEST...AGAIN AWAY FROM THE COOLER MARINE INFLUENCE. REGARDLESS OF WHETHER THERE IS A PREFRONTAL TROUGH...THE FRONT IS EXPECTED TO WONDER THROUGH IN THE EVENING HOURS...WITH A PERIOD OF POSSIBLE ADVISORY WINDS IN NW FLOW INTO EARLY WED MORNING. STRONG HIGH PRESSURE BUILDS IN WED NIGHT WITH QUIET WEATHER ON THE HORIZON. && .LONG TERM /THURSDAY THROUGH MONDAY/... FORECAST FOR THE PERIOD ON TRACK WITH THE CURRENT FORECAST. ONLY CHANGE WAS TO GO WITH LIKELY PROBABILITIES LATER THURSDAY NIGHT INTO FRIDAY AS CONSISTENCY REMAINS AND BEST CHANCES WILL BE IN THAT TIME FRAME. PRECIPITATION TYPES STILL AN ISSUE LATE THURSDAY NIGHT INTO FRIDAY MORNING ACROSS THE NORTHERN TIER AS AN EASTERLY FLOW DEVELOPS WITH HIGH PRESSURE MOVING EAST OF THE AREA...POSSIBLY KEEPING COLD AIR IN THE REGION. WILL BE A MARGINAL EVENT SO WENT WITH A MIX OF RAIN AND SNOW. MAINLY FOLLOWED HPC GUIDANCE ALONG WITH A BLEND OF SOME GFS IN THE EARLIER PERIODS AS MODEL DIFFERENCES ACROSS THE EASTERN UNITED STATES NOT YET SIGNIFICANT. DIFFERENCES MORE APPARENT AFTER THE PASSAGE OF THE COLD FRONT FRIDAY NIGHT...AS GFS DEVELOPS LOW OVER THE SOUTHEASTERN STATES SATURDAY ON THE STALLED FRONTAL BOUNDARY. KEPT SLIGHT CHANCE PROBABILITIES SATURDAY THROUGH MONDAY WITH THE UNCERTAINTY. && .AVIATION /0Z TUESDAY THROUGH SATURDAY/... TOUGH FORECAST THIS EVENING. WARM FRONT APPEARS TO HAVE JUMPED THROUGH ALL TAF TERMINALS WITH A RETURN TO VFR CONDITIONS EXCEPT AT KSWF...WHERE COLD AIR DAMMING HAS HAMPERED ITS PROGRESS AND IFR CONDITIONS REMAIN. HOWEVER TRENDS OVER THE LAST 2 HOURS ARE INDICATING THAT IT IS GETTING CLOSE. ADVECTION FOG AND STRATUS IS EXPECTED TO DEVELOP TONIGHT AS DEWPOINTS RISE TO AROUND THE 50 DEGREE MARK OVER WATER TEMPS IN THE MID 40S UNDER A SOUTHERLY LOW LEVEL FLOW. NO HINT OF IT AS OF 00Z...BUT THINK BY MIDNIGHT WE SHOULD SEE SOME INDICATION WITH CONDITIONS DROPPING BACK TO IFR/LIFR INTO EARLY TUE MORNING. SOME IMPROVEMENT TO MVFR IS POSSIBLE AFTER 14Z-15Z AT NYC AREA TERMINALS AS WARMER AIR MOVES IN FROM THE SOUTHWEST. S-SW WINDS SHOULD INCREASE DURING THE MORNING TO 15-20 KT WITH GUSTS 20-25 KT AS WELL. KOKX 00Z BALLOON ALREADY INDICATED 53KT WINDS AT 1300FT SO HAVE INCLUDED LLWS IN THE TAFS RIGHT OFF THE BAT FOR KISP...KBDR AND KGON. MODELS NOT HANDLING THE STRENGTH OF THE LLJ WELL AND DID NOT INDICATE LLWS BEING AN ISSUE UNTIL TUE MORNING. ACARS SOUNDING OUT OF KLGA AT 0030Z SHOWS 50KT WINDS ABOVE 2K FT WITH FORECAST SOUNDINGS INDICATING ONLY A GRADUAL INCREASE IN SPEED WITH HEIGHT OVERNIGHT SO HAVE NOT INCLUDED IT AT THE MAJOR TERMINALS. MOST TERMINALS SHOULD SEE IMPROVEMENT TO HIGH-END MVFR OR EVEN VFR DURING TUE AFTERNOON...BUT WITH GUSTY S-SW WINDS CONTINUING AHEAD OF AN APPROACHING COLD FRONT. THE COLD FRONT COULD BE PRECEDED BY A SQUALL LINE WITH BRIEF IFR...THUNDER AND GUSTY WINDS LATE TUE AFTERNOON INTO TUE EVENING BUT ITS TOO EARLY TO INCLUDE ATTM. OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY... CONDITIONS WILL IMPROVE BACK TO VFR BEHIND THE FROPA TUE EVE UNDER A GUSTY W-NW FLOW. SUB-VFR CONDITIONS IN RAIN...POSSIBLY MIXED WITH SNOW AT THE ONSET NORTH OF THE NYC TERMINALS...ARE ALSO LIKELY LATE THU NIGHT INTO FRI NIGHT. ANOTHER SYSTEM APPROACHES FROM THE SE STATES ON SAT WITH SUB-VFR CONDITIONS POSSIBLE AGAIN. && .MARINE... WINDS CONTINUE TO PICK UP SLOWLY THIS AFTERNOON...WITH 5FT SEAS OVER EASTERN OCEAN WATERS. LOW END SCA TONIGHT...BUT WITH DETERIORATING CONDITIONS TUESDAY. LOW END GALE FORCE WINDS ARE POSSIBLE TUESDAY AFTERNOON...BUT PRIMARILY IF CONVECTION DEVELOPS OR MOVES OUT OVER THE WATERS. OTHERWISE IT WILL BE HARD TO MIX GALE FORCE WINDS TO THE SURFACE. FROPA EXPECTED THURSDAY EVENING...WITH WINDS FLIPPING AROUND TO NW AND REMAINING STRONG INTO WED AM. THE CURRENT SCA GOES UNTIL 10Z...BUT MAY NEED TO BE EXTENDED FOR SEAS. HIGH PRESSURE OVER THE FORECAST WATERS WEDNESDAY NIGHT AND THURSDAY WILL KEEP THE AREA DRY AND WINDS AND SEAS BELOW ADVISORY LEVELS. A WARM FRONT APPROACHES THURSDAY NIGHT AND MAY LIFT THROUGH FRIDAY. PRECIPITATION BECOMES LIKELY THURSDAY NIGHT WITH REDUCED VISIBILITIES IN THE RAIN AND FOG. THE ASSOCIATED LOW WILL MOVE WEST AND NORTH...THEN NORTHEAST OF THE WATERS THURSDAY NIGHT INTO FRIDAY. A COLD FRONT WITH THE LOW MOVES THROUGH FRIDAY NIGHT. THE COLD FRONT STALLS EAST OF THE WATERS SATURDAY AND A WAVE DEVELOPS OVER THE SOUTHEASTERN STATES LATER SATURDAY. AN INCREASING SOUTHERLY FLOW AHEAD OF THE LOW FRIDAY WILL BUILD SEAS ON THE OCEAN TO SMALL CRAFT LEVELS. SEAS CONTINUE TO BUILD INTO FRIDAY NIGHT TO ABOUT 7 FEET. WITH THE PASSAGE OF THE COLD FRONT FRIDAY NIGHT WINDS SHIFT TO THE WEST AND SEAS WILL BEGIN TO SUBSIDE SATURDAY INTO SATURDAY NIGHT. && .HYDROLOGY... 1/4 TO 3/4 INCH QPF POSSIBLE MONDAY AFTERNOON THROUGH TUESDAY NIGHT WITH FRONTAL SYSTEM. HIGHEST QPF NW OF NYC AND IN THUNDERSTORMS TUESDAY. SHOULD NOT HAVE MUCH IF ANY IMPACT ON AREA RIVERS AND STREAMS WITH LONG DURATION EVENT. && .TIDES/COASTAL FLOODING... STRENGTHENING SOUTHERLY WINDS NOT EXPECTED TO PRODUCE SIGNIFICANT COASTAL FLOODING...BUT MAY RESULT IN HIGHER TIDAL RANGES TUESDAY AND TUESDAY NIGHT. BLOWOUT TIDES ALSO NOT EXPECTED TO HAVE SIGNIFICANT IMPACT. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM TUESDAY TO 6 AM EDT WEDNESDAY FOR ANZ330-335-338-340-345. SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ350-353- 355. && $$
AREA FORECAST DISCUSSION
NWS UPTON NY
430 PM EDT MON MAR 31 2008 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO SLIDE EAST THIS AFTERNOON. A WARM FRONT IS EXPECTED TO APPROACH LATER TODAY AND MOVES NORTH EARLY TUESDAY. A COLD FRONT SWEEPS ACROSS THE AREA TUESDAY NIGHT...FOLLOWED BY HIGH PRESSURE FOR MID WEEK. ANOTHER STORM SYSTEM APPROACHES LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... COLD AIR DAMMING HOLDING LOOSENING ITS GRIP ON THE REGION THIS AFTERNOON. TEMPS HAVE RISEN INTO THE 40S IN GENERAL WITH A FEW 50S POKING INTO CENTRAL/NRN NJ ATTM. THERE IS SOME INDICATION THAT A WARM FRONT IS MATERIALIZING OVER THE LI SOUND WITH COOLER TEMPS TO THE NORTH...BUT THERE IS NO APPRECIABLE WIND SHIFT. THE MOST SIGNIFICANT TEMP RISE REMAINS BACK OVER CENTRAL NJ. PRECIP IS VERY LIGHT BUT HAS INCREASED IN AREAL COVERAGE IN THE PAST FEW HOURS. ALTHOUGH THE HEAVIEST RAIN WILL REMAIN NORTH OF THE CWA...KEPT LIKELYS IN THE FORECAST FOR TONIGHT BUT LOW QPF. TEMPS EXPECTED TO REMAIN STEADY FOR A FEW HOURS THIS EVENING THEN RISE INTO THE 50S AS STRONGER SOUTHERLY FLOW DEVELOPS. 12Z MODELS IN GOOD AGREEMENT ON TEMP TRENDS...BUT STAYED CLOSER TO MAV NUMBERS WHICH WERE CLOSER TO REALITY WITH RESPECT TO CURRENT TEMPS. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... STRONG 70KT LL JET SETS UP ACROSS NYC AND POINTS EAST TUES AM. BUFKIT SOUNDINGS SUGGEST THAT WIND ADVISORY STRENGTH WINDS MOST LIKELY AT THE SURFACE AFTER 18Z TUES. THUS...HAVE HELD OFF ON ISSUING A WIND ADVISORY TO ALLOW THE NIGHT SHIFT TO FURTHER ANALYZE. THE OTHER ISSUE IS HOW FAR WEST TO BRING THE ADVISORY...AS IT APPEARS THERE WILL NOT BE A CLEAR DIFFERENTIATION BETWEEN ADV WINDS AND WEAKER WINDS TO THE WETS. AT THIS TIME IT APPEARS A GOOD DEMARCATION WILL BE THE HUDSON RIVER VALLEY...WITH NYC IN THE ADVISORY. WILL ALSO BE LOOKING AT VERY WARM TEMPS WITH THE LL JET DELIVERING 60-65 DEG AIR TO AREAS WITHOUT A MARINE INFLUENCE. ALL THIS WARMTH AND DYNAMICAL FORCING COULD ALSO RESULT IN POTENT CONVECTION...ESPECIALLY IF A SQUALL LINE DEVELOPS. BEST CHANCES FOR DAMAGING WINDS WILL BE FROM NYC NORTH AND WEST...AGAIN AWAY FROM THE COOLER MARINE INFLUENCE. REGARDLESS OF WHETHER THERE IS A PREFRONTAL TROUGH...THE FRONT IS EXPECTED TO WONDER THROUGH IN THE EVENING HOURS...WITH A PERIOD OF POSSIBLE ADVISORY WINDS IN NW FLOW INTO EARLY WED MORNING. STRONG HIGH PRESSURE BUILDS IN WED NIGHT WITH QUIET WEATHER ON THE HORIZON. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... FORECAST FOR THE PERIOD ON TRACK WITH THE CURRENT FORECAST. ONLY CHANGE WAS TO GO WITH LIKELY PROBABILITIES LATER THURSDAY NIGHT INTO FRIDAY AS CONSISTENCY REMAINS AND BEST CHANCES WILL BE IN THAT TIME FRAME. PRECIPITATION TYPES STILL AN ISSUE LATE THURSDAY NIGHT INTO FRIDAY MORNING ACROSS THE NORTHERN TIER AS AN EASTERLY FLOW DEVELOPS WITH HIGH PRESSURE MOVING EAST OF THE AREA...POSSIBLY KEEPING COLD AIR IN THE REGION. WILL BE A MARGINAL EVENT SO WENT WITH A MIX OF RAIN AND SNOW. MAINLY FOLLOWED HPC GUIDANCE ALONG WITH A BLEND OF SOME GFS IN THE EARLIER PERIODS AS MODEL DIFFERENCES ACROSS THE EASTERN UNITED STATES NOT YET SIGNIFICANT. DIFFERENCES MORE APPARENT AFTER THE PASSAGE OF THE COLD FRONT FRIDAY NIGHT...AS GFS DEVELOPS LOW OVER THE SOUTHEASTERN STATES SATURDAY ON THE STALLED FRONTAL BOUNDARY. KEPT SLIGHT CHANCE PROBABILITIES SATURDAY THROUGH MONDAY WITH THE UNCERTAINTY. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... MOST TERMINALS WERE EXPERIENCING IFR CONDITIONS IN LIGHT RAIN AS OF 1830Z...THE ONLY EXCEPTION BEING KGON WHICH SHOULD GO DOWN SHORTLY AS THE RAIN FINALLY ARRIVES THERE TOO. A WARM FRONT ADVANCING NORTHWARD INTO CENTRAL NJ SHOULD CONTINUE TO SLOW DOWN AS IT RUNS INTO MOIST RAIN-COOLED AIR FROM ABOUT NYC/PHL NORTH/WEST...BUT SHOULD GRADUALLY LIFT NORTHWARD INTO THE AREA MAINLY ACROSS NYC/LONG ISLAND/SOUTHERN CT THROUGH THIS EVENING AS NEARLY ALL STATIONS IN THE COASTAL PLAIN HAVE SOME SOUTHERLY WIND COMPONENT. EXACT TIMING OF WARM FROPA AND ANY SUBSEQUENT IMPROVEMENT ARE HIGHLY UNCERTAIN... WHILE CENTRAL/SOUTHERN NJ TERMINALS ARE VFR...THOSE AREAS ALSO DID NOT EXPERIENCE RAINFALL AND HAVE LARGER DEWPOINT DEPRESSIONS SUPPORTING HIGH-END MVFR OR EVEN VFR CIGS THERE. THINK IMPROVEMENT TO LOW-END MVFR IS POSSIBLE...FIRST AT KJFK AND KLGA/KISP BY 23Z AND 00Z...AND REACHING KBDR BY 02Z. KEWR/TEB/KHPN SHOULD REMAIN EITHER VERY CLOSE TO OR JUST WEST OF THE FRONT...WITH IFR CONDITIONS HANGING ON THERE DESPITE FLOW BECOMING MORE SOUTHERLY. AT ANY RATE...CONTINUED INFLUX OF HIGHER DEWPOINT AIR IN THE WARM SECTOR SHOULD EVENTUALLY BRING ALL TERMINALS BACK DOWN TO IFR/LIFR LATE TONIGHT INTO EARLY TUE MORNING...WITH SOME IMPROVEMENT TO MVFR POSSIBLE AFTER 14Z-15Z AT NYC AREA TERMINALS AS WARMER AIR MOVES IN FROM THE SOUTHWEST. S-SW WINDS SHOULD INCREASE DURING THE MORNING TO 15-20 KT WITH GUSTS 20-25 KT AS WELL. DID NOT INCLUDE LLWS INITIALLY WITH LOW LEVEL JET REMAINING AOA 2 KFT AND ACARS OBSERVED/MODEL FORECAST SOUNDINGS INDICATING ONLY A GRADUAL INCREASE IN SPEED WITH HEIGHT...BUT KISP/KGON COULD SEE LLWS LATE IN THE TAF PERIOD AS A SOUTHERLY 55-60 KT LOW LEVEL JET DEVELOPS ALONG THE COAST. OUTLOOK FOR 18Z TUESDAY THROUGH FRIDAY... MOST TERMINALS SHOULD SEE IMPROVEMENT TO HIGH-END MVFR OR EVEN VFR DURING TUE AFTERNOON...BUT WITH GUSTY S-SW WINDS CONTINUING AHEAD OF AN APPROACHING COLD FRONT. THE COLD FRONT COULD BE PRECEDED BY A SQUALL LINE WITH BRIEF IFR...THUNDER AND GUSTY WINDS LATE TUE AFTERNOON INTO TUE EVENING...THEN FOLLOWED BY IMPROVEMENT TO VFR LATE TUE NIGHT WITH GUSTY W-NW FLOW. SUB-VFR CONDITIONS IN RAIN...POSSIBLY MIXED WITH SNOW AT THE ONSET NORTH OF THE NYC TERMINALS...ARE ALSO LIKELY LATE THU NIGHT INTO FRI NIGHT. && .MARINE... WINDS CONTINUE TO PICK UP SLOWLY THIS AFTERNOON...WITH 5FT SEAS OVER EASTERN OCEAN WATERS. LOW END SCA TONIGHT...BUT WITH DETERIORATING CONDITIONS TUESDAY. LOW END GALE FORCE WINDS ARE POSSIBLE TUESDAY AFTERNOON...BUT PRIMARILY IF CONVECTION DEVELOPS OR MOVES OUT OVER THE WATERS. OTHERWISE IT WILL BE HARD TO MIX GALE FORCE WINDS TO THE SURFACE. FROPA EXPECTED THURSDAY EVENING...WITH WINDS FLIPPING AROUND TO NW AND REMAINING STRONG INTO WED AM. THE CURRENT SCA GOES UNTIL 10Z...BUT MAY NEED TO BE EXTENDED FOR SEAS. HIGH PRESSURE OVER THE FORECAST WATERS WEDNESDAY NIGHT AND THURSDAY WILL KEEP THE AREA DRY AND WINDS AND SEAS BELOW ADVISORY LEVELS. A WARM FRONT APPROACHES THURSDAY NIGHT AND MAY LIFT THROUGH FRIDAY. PRECIPITATION BECOMES LIKELY THURSDAY NIGHT WITH REDUCED VISIBILITIES IN THE RAIN AND FOG. THE ASSOCIATED LOW WILL MOVE WEST AND NORTH...THEN NORTHEAST OF THE WATERS THURSDAY NIGHT INTO FRIDAY. A COLD FRONT WITH THE LOW MOVES THROUGH FRIDAY NIGHT. THE COLD FRONT STALLS EAST OF THE WATERS SATURDAY AND A WAVE DEVELOPS OVER THE SOUTHEASTERN STATES LATER SATURDAY. AN INCREASING SOUTHERLY FLOW AHEAD OF THE LOW FRIDAY WILL BUILD SEAS ON THE OCEAN TO SMALL CRAFT LEVELS. SEAS CONTINUE TO BUILD INTO FRIDAY NIGHT TO ABOUT 7 FEET. WITH THE PASSAGE OF THE COLD FRONT FRIDAY NIGHT WINDS SHIFT TO THE WEST AND SEAS WILL BEGIN TO SUBSIDE SATURDAY INTO SATURDAY NIGHT. && .HYDROLOGY... 1/4 TO 3/4 INCH QPF POSSIBLE MONDAY AFTERNOON THROUGH TUESDAY NIGHT WITH FRONTAL SYSTEM. HIGHEST QPF NW OF NYC AND IN THUNDERSTORMS TUESDAY. SHOULD NOT HAVE MUCH IF ANY IMPACT ON AREA RIVERS AND STREAMS WITH LONG DURATION EVENT. && .TIDES/COASTAL FLOODING... STRENGTHENING SOUTHERLY WINDS NOT EXPECTED TO PRODUCE SIGNIFICANT COASTAL FLOODING...BUT MAY RESULT IN HIGHER TIDAL RANGES TUESDAY AND TUESDAY NIGHT. BLOWOUT TIDES ALSO NOT EXPECTED TO HAVE SIGNIFICANT IMPACT. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 AM TUESDAY TO 6 AM EDT WEDNESDAY FOR ANZ330-335-338-340-345. SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ350-353- 355. && $$ SYNOPSIS...BS NEAR TERM...BS SHORT TERM...BS LONG TERM...MET AVIATION...BG MARINE...BS/MET HYDROLOGY...BS TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS UPTON NY
334 PM EDT MON MAR 31 2008 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO SLIDE EAST THIS AFTERNOON. A WARM FRONT IS EXPECTED TO APPROACH LATER TODAY AND MOVES NORTH EARLY TUESDAY. A COLD FRONT SWEEPS ACROSS THE AREA TUESDAY NIGHT...FOLLOWED BY HIGH PRESSURE FOR MID WEEK. ANOTHER STORM SYSTEM APPROACHES LATE IN THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... COLD AIR DAMMING HOLDING ON ACROSS MUCH OF THE CWA WITH TEMPS IN THE LOW TO MID 40S ALONG THE COAST...AND UPPER 30S INLAND...AND LIGHT NE FLOW AT THE SURFACE. OVERRUNNING UNDERWAY WITH THICK CLOUD DECK AND LOWER BASES. PRECIP IS VERY LIGHT WITH THE BEST FORCING/FGEN TO THE NORTH OF THE CWA. AN UPDATE WAS ISSUED TO LOWER POPS ACROSS THE BOARD AND ADD DRIZZLE TO THE WX GRIDS. KEPT LIKELYS FOR CT/LOWER HUDSON VALLEY ZONES...BUT THINK IT WILL BE MORE OCCASIONAL RAIN THAN STEADY. DRY SUBCLOUD LAYER IN COLD AIR DAMMING THE LIKELY CULPRIT KEEPING PRECIP AT BAY. COOL AIR AT THE SURFACE MAY BE EVEN HARDER TO SCOUR OUT THAN THOUGHT. WARM FRONT AT THE SURFACE JUST WENT THROUGH ACY IN THE LAST HOUR...AND POSSIBLE SFC REFLECTION OUT OVER THE ATLANTIC AT BUOY 44025...BUT NORTHWARD PROGRESSION IS VERY SLOW. MODEL HANDLING OF COLD AIR DAM RETREAT IS HORRIBLE IN GENERAL...SO THIS IS A TOUGH FORECAST. 12Z NAM SHOWS THE WARM FRONT OVER CENTRAL CT BY 00Z TONIGHT. *FROM PREVIOUS DISCUSSION* RIDGE AXIS SLIDES EAST TONIGHT WHILE UPPER TROUGH SHARPENS AS IT SLIDES INTO THE UPPER GREAT LAKES...RESULTING IN A STRENGTHENING SW LLJ AND DEEP LAYERED MOISTURE ACROSS THE REGION. STILL ANTICIPATE SURFACE WARM FRONT REMAINING JUST SOUTH OF MOST OF THE REGION TONIGHT (MAY MEANDER THROUGH WESTERN ZONES IN THIS STRONG SW FLOW AND PERHAPS THE IMMEDIATE SOUTH COAST) AS IS CLIMATOLOGICALLY THE CASE...BUT THE 850 HPA FRONT SHOULD TRACK NORTH THROUGH THE REGION OVERNIGHT. THE ASSOCIATED LIFT ABOVE THIS BOUNDARY AND AMPLE MOISTURE WILL RESULT IN CAT/LIKELY RAIN ACROSS THE ENTIRE REGION. SOME ADVECTION FOG POSSIBLE AHEAD OF THE SURFACE WARM FRONT...AS DEW POINTS WARM ABOVE OCEAN TEMPS. TEMPS WILL EITHER REMAIN STEADY...OR RISE THROUGH THE NIGHT...RUNNING A GOOD 7 TO 10 DEGREES ABOVE SEASONABLE. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... ON TUESDAY...SHORTWAVE ENERGY PIVOTS INTO THE EASTERN GREAT LAKES WELL TO OUR NORTH AND WEST...WITH SURFACE LOW TRACKING FROM SOUTHERN ONTARIO INTO QUEBEC. EXPECT THE AFOREMENTIONED STRONG SFC FLOW AND LOW LEVEL JET TO PUSH SURFACE WARM FRONT TO THE NORTH IN THE MORNING. LOCAL CWA GETS WARM SECTORED. LOCATIONS AWAY FROM WATER INFLUENCE COULD WARM UP WELL INTO THE 60S...AND WOULD NOT BE SURPRISED TO SEE A FEW 70 DEGREE READINGS ACROSS NE NJ. MOS CATCHING ON TO THIS AND LEANED TOWARD WARMER MET NUMBERS AS TEMPS WARM TO +10C ALOFT. GFS IS FASTER THAN NAM WITH TIMING OF COLD FRONTAL APPROACH...SO FOR NOW WILL GO MIDDLE OF ROAD WITH TIMING. SIMILAR TO ECMWF WITH COLD FRONT REACHING WESTERN SECTIONS BY AROUND 00Z. BOTH GFS/NAM ARE HINTING AT A PRE-FRONTAL TROUGH DEVELOPING TUES AFTERNOON WITH DECENT INSTABILITY/LIFT AXIS DEVELOPING AHEAD OF IT AS 60+ KT LLJ PUMPS TEMPS TO 60+ F AND TDS TO 50+ F. BEST CHANCE OF CONVECTION WILL BE ACROSS CITY AND N & W SECTIONS...WITH MARGINAL SURFACE INSTABILITY. IF ANY STRONG CONVECTION DEVELOPS ACROSS THE INTERIOR...DAMAGING WINDS ARE A POSSIBILITY. HAVE INCREASED POPS TO CAT/LIKELY ACCORDINGLY. EXPECT IT TO BE WINDY IN GENERAL...WITH WINDS IN THE 20 TO 30 MPH RANGE AND GUSTS TO AROUND 40 MPH POSSIBLE. HIGHEST SUSTAINED WINDS WILL LIKELY BE ALONG THE IMMEDIATE COAST...WITH STRONGEST GUSTS ACROSS CITY/INTERIOR(HIGHER ELEVATIONS) WITH BEST HEATING AND STEEPEST LAPSE RATES. SOUNDINGS ARE UNDERDOING THE SURFACE HEATING ACROSS THE INTERIOR(LOWER 60S)...WHICH WOULD ALLOW FOR WINDS TO BE MIXED DOWN FROM A BIT HIGHER THAN SUGGESTED (950 HPA WINDS AROUND 40KT). LOOKS TO BE JUST BELOW WIND ADVISORY...BUT WILL HAVE TO BE RE-EVALUATED BY NEXT COUPLE OF SHIFTS. WILL GO WITH COMPROMISE COLD FRONTAL PASSAGE TO THE EAST OF CWA BY AROUND MIDNIGHT. BEST DYNAMICS SWING WELL TO THE NORTH WITH SHORTWAVE ENERGY ACROSS CENTRAL NY AND CENTRAL NEW ENGLAND. PRECIP/CONVECTION AHEAD OF THE FRONT...ACROSS WESTERN CWA DURING AFTERNOON...WILL LIKELY BE WEAKENING AS IT PUSHES INTO MORE STABLE AIRMASS ACROSS EASTERN HALF OF CWA AND WITH WEAKENED DYNAMICS. WILL TAPER FROM LIKELY POPS IN THE EVENING TO CHANCE POPS FROM W TO E AS THE FRONT COMES THROUGH. A SLIGHT CHANCE OF THUNDER EXISTS INTO THE EVENING WITH MARGINAL ELEVATED INSTABILITY AND LOW-LEVEL CONVERGENCE ALONG THE FRONT. COLD FRONT SHOULD PUSH EAST AFTER MIDNIGHT..WITH WNW FLOW EXPECTED IN ITS WAKE WITH BURST OF CAA AND STRONG PRESSURE RISE. COULD SEE SOME WINDS GUSTS IN EXCESS OF 40 MPH IN ITS WAKE. CURRENTLY LOOKS LIKE WINDS COULD BE MARGINAL WIND ADVISORY STRENGTH ACROSS ENTIRE CWA FOR A 2 TO 4 HR DURATION...BUT WILL HAVE TO RE-EXAMINE OVER NEXT COUPLE OF SHIFTS. UPPER TROUGH SLIDES THROUGH NORTHERN NEW ENGLAND ON WEDNESDAY...WITH LOW PRESSURE LIFTING INTO THE CANADIAN MARITIMES. DEEP W/NW FLOW WILL ENSURE PLENTY OF SUNSHINE THROUGH THE DAY. A TIGHT NW GRADIENT BETWEEN THE DEPARTING LOW AND HIGH PRESSURE BUILDING IN FROM THE OHIO VALLEY AND MODERATE CAA WILL LIKELY HAVE STRONG GUSTY WNW WINDS CONTINUING EARLY WED MORNING...COULD STILL SEE SOME GUSTS UP TO 40 MPH IN THE MORNING. BUT AS DAY WEARS ON WINDS ALOFT WEAKEN...SO DESPITE STEEPENING LAPSE RATES...GUSTS SHOULD FALL BACK INTO THE 30S. CAA FLOW LOOKS TO DROP 850 HPA TEMPS DROP TO -8C THROUGH THE DAY. SO HIGH TEMPS WILL LIKELY BE REACHED BY MIDDAY...AND THEN LEVELING OUT (GENERALLY AROUND 50). && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... GFS COMING INTO BETTER AGREEMENT WITH THE FORECAST...AND WAS FAVORED FOR THE EXTENDED PERIOD TO KEEP CONTINUITY. ZONAL FLOW WILL KEEP SYSTEMS MOVING ALONG AS SURFACE HIGH BUILDS INTO THE AREA WEDNESDAY NIGHT INTO THURSDAY...SHIFTING OFF THE COAST DURING THE DAY. RIDGE IS A LITTLE SLOWER TO MOVE OFF DURING THURSDAY...THUS HOLDING THE APPROACH OF THE WARM FRONT UNTIL THURSDAY NIGHT. ALSO SURFACE LOW WEST OF THE APPALACHIANS SO WARM FRONT WILL GET HUNG UP IN THE ROUGHER TERRAIN. WILL REMOVE THE PROBABILITIES FROM THURSDAY BASED ON THE SLIGHTLY SLOWER TIMING. WARM FRONTAL PASSAGE WILL HOLD OFF UNTIL FRIDAY...WHEN AREA WILL BRIEFLY GET INTO THE WARM AIR. SO TEMPERATURES FRIDAY A FEW DEGREES HIGHER THAN PREVIOUS FORECAST. COULD BE A MIX OF SNOW AND RAIN ACROSS THE INTERIOR LATE THURSDAY NIGHT INTO FRIDAY MORNING. COLD FRONT COMING THROUGH FRIDAY NIGHT. COULD BE A FEW SHOWERS BEHIND THE FRONT FRIDAY NIGHT INTO SATURDAY MORNING. NO REAL SURGE OF COLD AIR AND PRESSURE GRADIENT WEAK...SO ALL LIQUID SHOULD FALL BEHIND THE FRONT AND WINDS WILL REMAIN RATHER WEAK. FULL AMPLITUDE UPPER TROUGH REMAINS ACROSS THE EAST SATURDAY NIGHT INTO SUNDAY WITH WEAK SURFACE HIGH. WILL LIKELY SEE LOTS OF CLOUDS BUT WITH NOT FORCING NO PRECIPITATION. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... MOST TERMINALS WERE EXPERIENCING IFR CONDITIONS IN LIGHT RAIN AS OF 1830Z...THE ONLY EXCEPTION BEING KGON WHICH SHOULD GO DOWN SHORTLY AS THE RAIN FINALLY ARRIVES THERE TOO. A WARM FRONT ADVANCING NORTHWARD INTO CENTRAL NJ SHOULD CONTINUE TO SLOW DOWN AS IT RUNS INTO MOIST RAIN-COOLED AIR FROM ABOUT NYC/PHL NORTH/WEST...BUT SHOULD GRADUALLY LIFT NORTHWARD INTO THE AREA MAINLY ACROSS NYC/LONG ISLAND/SOUTHERN CT THROUGH THIS EVENING AS NEARLY ALL STATIONS IN THE COASTAL PLAIN HAVE SOME SOUTHERLY WIND COMPONENT. EXACT TIMING OF WARM FROPA AND ANY SUBSEQUENT IMPROVEMENT ARE HIGHLY UNCERTAIN... WHILE CENTRAL/SOUTHERN NJ TERMINALS ARE VFR...THOSE AREAS ALSO DID NOT EXPERIENCE RAINFALL AND HAVE LARGER DEWPOINT DEPRESSIONS SUPPORTING HIGH-END MVFR OR EVEN VFR CIGS THERE. THINK IMPROVEMENT TO LOW-END MVFR IS POSSIBLE...FIRST AT KJFK AND KLGA/KISP BY 23Z AND 00Z...AND REACHING KBDR BY 02Z. KEWR/TEB/KHPN SHOULD REMAIN EITHER VERY CLOSE TO OR JUST WEST OF THE FRONT...WITH IFR CONDITIONS HANGING ON THERE DESPITE FLOW BECOMING MORE SOUTHERLY. AT ANY RATE...CONTINUED INFLUX OF HIGHER DEWPOINT AIR IN THE WARM SECTOR SHOULD EVENTUALLY BRING ALL TERMINALS BACK DOWN TO IFR/LIFR LATE TONIGHT INTO EARLY TUE MORNING...WITH SOME IMPROVEMENT TO MVFR POSSIBLE AFTER 14Z-15Z AT NYC AREA TERMINALS AS WARMER AIR MOVES IN FROM THE SOUTHWEST. S-SW WINDS SHOULD INCREASE DURING THE MORNING TO 15-20 KT WITH GUSTS 20-25 KT AS WELL. DID NOT INCLUDE LLWS INITIALLY WITH LOW LEVEL JET REMAINING AOA 2 KFT AND ACARS OBSERVED/MODEL FORECAST SOUNDINGS INDICATING ONLY A GRADUAL INCREASE IN SPEED WITH HEIGHT...BUT KISP/KGON COULD SEE LLWS LATE IN THE TAF PERIOD AS A SOUTHERLY 55-60 KT LOW LEVEL JET DEVELOPS ALONG THE COAST. OUTLOOK FOR 18Z TUESDAY THROUGH FRIDAY... MOST TERMINALS SHOULD SEE IMPROVEMENT TO HIGH-END MVFR OR EVEN VFR DURING TUE AFTERNOON...BUT WITH GUSTY S-SW WINDS CONTINUING AHEAD OF AN APPROACHING COLD FRONT. THE COLD FRONT COULD BE PRECEDED BY A SQUALL LINE WITH BRIEF IFR...THUNDER AND GUSTY WINDS LATE TUE AFTERNOON INTO TUE EVENING...THEN FOLLOWED BY IMPROVEMENT TO VFR LATE TUE NIGHT WITH GUSTY W-NW FLOW. SUB-VFR CONDITIONS IN RAIN...POSSIBLY MIXED WITH SNOW AT THE ONSET NORTH OF THE NYC TERMINALS...ARE ALSO LIKELY LATE THU NIGHT INTO FRI NIGHT. && .MARINE... WINDS PICK UP FROM THE SOUTHEAST TO SOUTH TODAY...WITH WINDS AND REMAINING BELOW SCA CRITERIA THROUGH THE DAY. HAVE DECIDED TO KEEP START TIME OF SCA ON THE OCEAN AS IS...WITH THE POSSIBILITY OF 5 FT SEAS HERE LATE IN THE AFTERNOON. WARM FRONT WILL ATTEMPT TO PUSH THROUGH THE WATERS TONIGHT...BUT THIS LOOKS MORE LIKELY TO HAPPEN TUESDAY TOMORROW MORNING. SCA LEVEL GUSTS SHOULD BE LIMITED TO ONLY THE OCEAN WATERS. ELSEWHERE...25 KT GUSTS NOT UNTIL 3RD PERIOD...SO WILL NOT HOIST FLAGS HERE FOR NOW. WITH THE WARM FRONT NORTH OF ALL WATERS ON TOMORROW...GUSTS ON ALL WATERS TO SCA LEVELS. SCA NOW EXTENDED THROUGH TUESDAY AFTERNOON ON THE OCEAN...AND WILL LIKELY NEED TO BE EXTENDED ON NEXT SHIFT. STILL NOT CONFIDENT THAT GALES WILL BE REACHED BEFORE COLD FRONT APPROACHES LATE TUESDAY NIGHT WITH LOW LEVEL INVERSION IN PLACE OVER THE WATERS. GALES PRECEDING THE FRONT MIGHT ONLY HAVE A CHANCE TO OCCUR IN ANY CONVECTION THAT COULD DEVELOP. BEHIND THE FRONT...A BRIEF PERIOD OF NEAR GALE GUSTS...BUT WINDS SHOULD SUBSIDE THROUGH THE DAY ON WEDNESDAY AS HIGH PRESSURE QUICKLY BUILDS IN BEHIND THE DEPARTING FRONT. OCEAN SEAS BUILDING TO 7-11 FT AHEAD OF THE FRONT...THEN DROPPING BELOW 5 FT BY LATE IN IN THE DAY WEDNESDAY. TRANQUIL CONDITIONS THEN THROUGH THURSDAY. NEXT SYSTEM MAY BRING OCEAN SEAS BACK UP TO 5FT BY LATE THURSDAY NIGHT...BUT MORE LIKELY TO OCCUR ON FRIDAY. && .HYDROLOGY... 1/4 TO 3/4 INCH QPF POSSIBLE MONDAY AFTERNOON THROUGH TUESDAY NIGHT WITH FRONTAL SYSTEM. HIGHEST QPF NW OF NYC. SHOULD NOT HAVE MUCH IF ANY IMPACT ON AREA RIVERS AND STREAMS WITH LONG DURATION EVENT. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 6 PM EDT TUESDAY FOR ANZ350-353-355. && $$ SYNOPSIS...BS NEAR TERM...BS SHORT TERM...BS LONG TERM...NV AVIATION...BG MARINE...JC HYDROLOGY...NV
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1157 PM EDT MON MAR 31 2008 .AVIATION...THE SNOW WILL STAY NORTH OF THE STRAITS THROUGH 12Z. THUNDER IS A POSSIBILITY, ESPECIALLY NEAR TVC AND APN AS A LINE HAS FORMED NEAR ORD. HOWEVER, AS THE HISTORY OF MOST OF THE THUNDER THIS EVENING IS ANY GUIDE, THE LIGHTNING WILL GRADUALLY THIN OUT TO NOTHING BY THE TIME IT GETS NORTH OF M-55. AFTER 12Z, THE COLD AIR WILL MOVE IN AND CHANGE THE RAIN TO SNOW. LUTZ && .PREV DISCUSSION... /ISSUED 1137 PM EDT MON MAR 31 2008/ UPDATE...SINCE THE LAST UPDATE, THUNDER REDEVELOPED NEAR CHICAGO AND IS ON ITS WAY INTO THE FORECAST AREA NEAR THE M-55 CORRIDOR. SO HAVE TRIED TO TIME THE THUNDER ACROSS THE SOUTHERN PART OF THE REGION FOR THE REMAINDER OF THE NIGHT. SO FAR, THE REST OF THE FORECAST LOOKS GOOD. LUTZ PREV DISCUSSION... /ISSUED 938 PM EDT MON MAR 31 2008/ UPDATE...AM IN THE PROCESS OF TAKING SOME OF THE THUNDER OUT OF THE FORECAST, AS THE MIDLEVEL DRY SLOT LOOKS TO BE MOVING INTO THE REGION PUTTING A CAP ON THE THUNDER AND MOST OF THE RAIN. NORTH OF THE WARM FRONT THE F-GEN LOOKS TO BE GENERATING MORE RAIN, SNOW AND SLEET IN C AND E UPPER. THERE IS EVEN SOME THUNDER NORTH OF THE FRONT. SO HAVE UPDATED THE ZONES TO TAKE SOME OF THE THUNDER OUT, BUT IT LOOKS LIKE THAT THE THUNDER NEEDS TO BE TAKEN OUT OF THE FORECAST FOR AN AREA SOUTH OF A LINE FROM TVC TO APN AT THE LEAST. WILL PROBABLY HAVE ANOTHER UPDATE OUT SOON. LUTZ PREV DISCUSSION... /ISSUED 436 PM EDT MON MAR 31 2008/ SYNOPSIS...A STRONG STORM SYSTEM WILL MOVE INTO CENTRAL LOWER MICHIGAN TONIGHT. WIDESPREAD PRECIPITATION WILL OVERSPREAD THE REGION RESULTING IN POTENTIAL HEAVY RAIN AND SNOW. THIS STORM SYSTEM WILL EXIT THE REGION TUESDAY WHILE COLD AIR AND STRONG WINDS PLOW INTO ALL OF MICHIGAN. HIGH PRESSURE WILL THEN SETTLE IN WEDNESDAY WITH SEASONABLE TEMPERATURES THROUGH THE REMAINDER OF THE WEEK. DISCUSSION...SFC/RUC/SATELLITE/RADAR AND UPPER AIR ANALYSIS SHOWING SHORTWAVE TROUGH LIFTING OUT OF THE ROCKIES WHILE SFC LOW PRESSURE IS DEEPENING OVER NRN MO/SRN IOWA AS IT CONTINUES TO LIFT NORTHEAST. STORMS HAVE FIRED ALONG THE COLD FRONT WHICH WAS DRAPED FROM THE LOW...TO MO/AR/OK. THIS IS SEEMINGLY ROBBING US OF SOME OF THE DEEPEST MOISTURE TO THE SOUTH. TEMPERATURES HAVE BEEN VERY SLOW TO CLIMB...AS WARM FRONT REMAINS TO THE SOUTH OF US...AND AN EASTERLY FLOW OFF THE LAKE HAS KEPT READINGS IN THE 30S. INITIAL SHORTWAVE WORKING INTO THE WESTERN GREAT LAKES AND WAS RESULTING IN EXPANDING RAIN SHIELD SPREADING INTO NRN MICHIGAN. TONIGHT...SFC OW WILL WORK INTO CENTRAL LOWER TONIGHT AND STRONGEST H7-H5 -DIVQ SPREADS IN ACROSS UPPER MICHIGAN WITH A SECOND AREA ACROSS SRN LOWER THIS EVENING. THIS FORCING COMBINED WITH H3-H2 UPPER DIVERGENCE ASSOCIATED WITH STRONG UPPER JET OF 120KTS AND STRONG AND DEEP FGEN RESPONSE SUGGESTIVE OF ENHANCED BANDED PRECIPITATION. MODEL CROSS SECTIONS SHOW THE STRONG SLOPED FRONTAL SURFACE WITH -EPV AND BULLSEYE OF LIFT CENTERED OVER PLN. AREA TAMDAR SOUNDINGS ARE SUPPORTING NAM/GFS SOUNDINGS OF MAINLY A SNOW EVENT ACROSS CHIPPEWA COUNTY...MIXED SNOW AND SLEET ACROSS MAINLY MACKINAC COUNTY...AND ALL RAIN FOR PRETTY MUCH ALL OF NRN LOWER MICHIGAN. THERE IS A +1.5C SWATCH OF AIR THROUGH 3KFT ACROSS CIU...BUT WITH A BIT OF DRY AIR BELOW THIS (CIGS 6KFT)...EVAP COOLING SHOULD ALLOW ANY ONSET OF RAIN...TO SWITCH OVER TO SNOW RATHER QUICKLY. THIS ESPECIALLY TRUE IN THE PRESENCE OF SUCH STRONG VERTICAL MOTIONS THAT ARE EXPECTED. OVERALL...STILL SEE POTENTIALLY 10 INCHES OF SNOW NEAR PARADISE TAPERING OFF RATHER QUICKLY TO MAYBE A COUPLE OF INCHES NEARER TO DRUMMOND ISLAND. CONVECTIVE ACTIVITY COULD ALLOW FOR SNOW TO MIX IN WITH RAIN ACROSS PORTIONS OF FAR NRN LOWER...BUT AGAIN...MAINLY RAIN EXPECTED. FINALLY...LOOK FOR STRONG WINDS TO DEVELOP LATE TONIGHT ACROSS WHITEFISH BAY AS LOW PASSES EAST AND COLD AIR STARTS TO WORK INTO FAR WESTERN CHIP/MACK. COULD SEE GUSTS TO 35 MPH DEVELOP LATE...AND QUITE POSSIBLY ACROSS WHITEFISH BAY THIS EVENING TOO. THE STRONG WINDS WILL DEVELOP OVER ALL OF NRN MICHIGAN TUESDAY. TEMPERATURES WILL ACTUALLY RISE OVERNIGHT IN AREAS SOUTH OF M-32 AS WARM FRONT LIFTS NORTH OF THIS AREA. THERE IS A CHANCE THAT GUSTY WINDS COULD DEVELOP NEAR THE BAY...BUT GOING INTO NIGHT TIME...DO NOT SEE WHERE DEEP ENOUGH MIXING COULD MAKE THIS A FACTOR. WILL HAVE READINGS RISING INTO THE MIDDLE 40S FOR THESE AREAS...WHILE TEMPERATURES REMAIN NEARLY STEADY IN THE 30S OR SLOWLY FALL (EASTERN UPPER). SMD TUESDAY...THE STORM SYSTEM WILL BE LOCATED BETWEEN SAGINAW BAY AND ALPENA ALONG THE LAKE HURON SHORELINE AT 12Z...EXITING QUICKLY TO THE NORTHEAST OF LAKE HURON DURING THE AFTERNOON. ADDITIONAL LIFT TUESDAY...WILL BE FROM A 500MB TROUGH SWEEPING OVER THE GREAT LAKES REGION DURING THE DAY. THIS TROUGH IS ALSO EXPECTED TO MOVE EAST OF LAKE HURON BY THE AFTERNOON. 850-700MB FRONTOGENESIS SHOWS THE BEST LIFT WITH THE EXITING SFC LOW...TO REMAIN OVER THE STRAITS AND EAST UPPER MICHIGAN...MAINLY INTO THE AFTERNOON BEFORE DIMINISHING BY EVENING. MODEL SOUNDINGS FROM THE STRAITS NORTH...SHOW ABUNDANT MSTR FROM THE SFC THROUGH 500MB...WITH AN ENTIRE SOUNDING BELOW FREEZING. QPF FORECAST WOULD SUGGEST ANOTHER 3 TO 5 INCHES POSSIBLE IN THE REGION INTO THE AFTERNOON...THEREFORE WILL LEAVE WINTER STORM WARNING IN EFFECT FOR EAST UPPER. FOR NORTHERN LOWER MICHIGAN LOCATIONS WEST OF I-75...SOUNDINGS SHOW SOME MIX POSSIBLE FIRST THING IN THE MORNING QUICKLY BECOMING SNOW...THEN POSSIBLE DRIZZLE IN THE AFTERNOON AS MID AND UPPER LVL MSTR STRIPS OUT. FOR THE REST OF NRN LOWER MICHIGAN...850MB WET BULBS WILL BE ABOVE ZERO IN THE MORNING DROPPING BELOW ZERO IN THE AFTERNOON. THEREFORE WILL CONTINUE A CHANCE OF RAIN/DRIZZLE IN THE MORNING...BEFORE BECOMING LIGHT SNOW IN THE AFTERNOON. WILL HAVE GALE WARNINGS OVER NRN MICHIGAN NEARSHORES IN EFFECT THROUGH TUESDAY AFTERNOON...AS WIND GUSTS BEHIND THE EXITING FRONT INCREASE TO BTW 35 AND 40KTS. WILL CONTINUE GALE WARNINGS INTO THE EARLY EVENING BEFORE WINDS DIMINISH WITH INCREASE HIGH PRESSURE. THE STRONG WINDS WILL ALSO RESULT IN BLOWING AND DRIFTING SNOW ACROSS EASTERN UPPER THAT COULD POTENTIALLY RESULT IN SIGNIFICANTLY REDUCED VISIBILITIES. TUESDAY NIGHT...A STRONG AREA OF HIGH PRESSURE WILL BUILD BACK INTO THE WRN LAKES FROM THE UPPER MIDWEST EARLY TUESDAY EVENING... ACCOMPANIED BY 500MB ZONAL FLOW ALOFT. MODEL SOUNDINGS AND MSTR PROGS SHOWING DRYING CONDS MOVING OVER THE GREAT LAKES REGION QUICKLY DURING THE EVENING...DROPPING TO AROUND 30 PCT BETWEEN 850-500 AROUND 00Z WED. OVERALL WILL MAINTAIN THE DRY CONDITIONS OVER THE FORECAST. HOWEVER WILL MENTION SOME EARLY EVENING LAKE INDUCED SNOW SHOWERS OVER PORTIONS OF NORTHWEST LOWER AND EAST UPPER MICHIGAN. 850 MB TEMPS ARE PROGGED AROUND -12C...WITH NRN LAKE MI WATER TEMPS NEAR +1C. 925-850 MB WINDS WILL BE FROM THE NORTHWEST WITH 900-700 MB RH ARND 80 PCT...QUICKLY DRYING TO UNDER 30 PCT BY 06Z. MODEL SOUNDINGS SHOW AN INVERSION HEIGHT AROUND 5K FT AROUND 00Z...QUICKLY DIMINISHING TO UNDER 3500FT BY 06Z. SNOWFALL AMOUNTS WILL BE UNDER ONE INCH...AS LW LVL MSTR DOES NOT EXTEND UP MUCH PASS -11C DURING THIS PERIOD AND MODELS SHOW DRY AIR QUICKLY MOVING BACK IN. WEDNESDAY/WEDNESDAY NIGHT...A LARGE AREA OF HIGH PRESSURE IS PROGGED TO MOVE OVER THE UPPER MIDWEST WEDNESDAY MORNING...BECOMING CENTERED OVER THE REGION IN THE AFTERNOON. THE HIGH IS FORECAST TO MOVE EAST ONTO THE MID ATLANTIC COAST BY 12Z THURSDAY...HOWEVER SFC RIDGING IS FORECAST TO LINGER OVER THE GREAT LAKES REGION INTO THURSDAY. AT UPPER LEVELS 500 MB...APPEARS TO BE ZONAL THRU THE PERIOD WITH A WEAK UPPER TROUGH SLIDING INTO THE WRN LAKES REGION THURSDAY MORNING. OVERALL WILL CONTINUE WITH DRY CONDS WED AND WED NIGHT. HIGH TEMPERATURES...WITH AT LEAST PARTIAL SUNSHINE AND 850 MB TEMPS RUNNING AROUND -4C...WOULD SUGGEST HIGH TEMPERATURES FROM AROUND 40 OVER EAST UPPER MICHIGAN TO THE MID 40S OVER THE SOUTHERN PORTIONS OF THE FORECAST AREA. WILL MENTION OVERNIGHT LOWS FALLING BACK TO NEARLY NORMAL IN THE MID 20S...AS SKIES SHOULD REMAIN FAIRLY CLEAR OVERNIGHT. THURSDAY...HIGH PRESSURE RIDGING STILL THE DOMINATE FEATURE OVER THE GREAT LAKES THRU MUCH OF THE PERIOD...WHILE THE UPPER LEVELS REMAIN FAIRLY ZONAL THRU THE AFTN. OVERALL WILL MENTION PARTLY SUNNY SKIES AND DRY CONDITIONS THROUGH THE DAY. AFTERNOON HIGHS SHOULD ONCE AGAIN BE IN THE MID 40S WITH 850 MB TEMPS AROUND -3C AND SOME SUN...AND POSSIBLY LESS SNOW COVER. WILL KEEP THE MENTION OF A CHANCE OF PCPN OVER THE SOUTHEAST CWA THURSDAY NIGHT AS A SHORT WAVE TROUGH MOVES OVER THE UPPER MIDWEST AND WRN LAKES REGION. THIS WILL COMBINE WITH A STORM SYSTEM PROGGED TO MOVE ONCE AGAIN INTO THE OHIO VALLEY. WILL MENTION THIS PCPN AS MAINLY SNOW AS OVERNIGHT LOWS FALL INTO THE MID 20S...ALONG WITH BEING WELL NORTH OF THE OHIO VALLEY STORM SYSTEM. FRIDAY THRU MONDAY...UPPER LEVEL PATTERN SHOWING NEARLY ZONAL FLOW ACRS THE UPPER LAKES FRIDAY THROUGH SATURDAY. PATTERN AT THE SFC A LITTLE LESS ORGANIZED AND NON-DISTINCT...WITH WEAK HIGH PRESSURE OVER THE REGION THRU SATURDAY WHILE A STORM SYSTEM REMAINS OVER HUDSON BAY. 850MB TEMP PATTERN REMAINS THE SAME...GENERALLY HANGING AROUND -3C TO -4C WHICH SHOULD GENERATE TEMPS IN THE MID 40S ACROSS MUCH OF NRN LOWER WITH LOWER 40S OVER EAST UPPER. THE SRN PORTIONS OF THE FORECAST AREA SHOULD BEGIN WARMING QUITE EFFICIENTLY THIS WEEKEND AS SNOW LINE CONTINUES TO SLOWLY MOVE NORTH. WILL MENTION A CHANCE OF PCPN SUNDAY...AS UPPER TROUGH STRENGTHENS OVER THE UPPER LAKES...FROM A LOW CENTERED OVER HUDSON BAY. THE SFC RESPONSE IS A WEAK BOUNDARY PROGGED TO MOVE OVER THE STATE SUNDAY...WITH HIGH PRESSURE PROGGED TO MOVE BACK OVER THE STATE SUNDAY NIGHT AND MONDAY. WILL KEEP THE FORECAST AREA DRY MONDAY WITH THE RIDGE OF HIGH PRESSURE MOVING OVER THE WRN LAKES...WILL MENTION WARMER HIGHS FOR THE SRN CWA DUE TO LACK OF SNOW BY THAT TIME AND POTENTIAL FOR SUN. SWR && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WARNING UNTIL 5 PM EDT TUESDAY FOR MIZ008-015. LM...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LMZ323-341-342- 344>346. LH...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LHZ345>349. LS...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LSZ322. GALE WARNING UNTIL 11 PM EDT TUESDAY FOR LSZ321. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1137 PM EDT MON MAR 31 2008 .UPDATE...SINCE THE LAST UPDATE, THUNDER REDEVELOPED NEAR CHICAGO AND IS ON ITS WAY INTO THE FORECAST AREA NEAR THE M-55 CORRIDOR. SO HAVE TRIED TO TIME THE THUNDER ACROSS THE SOUTHERN PART OF THE REGION FOR THE REMAINDER OF THE NIGHT. SO FAR, THE REST OF THE FORECAST LOOKS GOOD. LUTZ && .PREV DISCUSSION... /ISSUED 938 PM EDT MON MAR 31 2008/ UPDATE...AM IN THE PROCESS OF TAKING SOME OF THE THUNDER OUT OF THE FORECAST, AS THE MIDLEVEL DRY SLOT LOOKS TO BE MOVING INTO THE REGION PUTTING A CAP ON THE THUNDER AND MOST OF THE RAIN. NORTH OF THE WARM FRONT THE F-GEN LOOKS TO BE GENERATING MORE RAIN, SNOW AND SLEET IN C AND E UPPER. THERE IS EVEN SOME THUNDER NORTH OF THE FRONT. SO HAVE UPDATED THE ZONES TO TAKE SOME OF THE THUNDER OUT, BUT IT LOOKS LIKE THAT THE THUNDER NEEDS TO BE TAKEN OUT OF THE FORECAST FOR AN AREA SOUTH OF A LINE FROM TVC TO APN AT THE LEAST. WILL PROBABLY HAVE ANOTHER UPDATE OUT SOON. LUTZ PREV DISCUSSION... /ISSUED 436 PM EDT MON MAR 31 2008/ SYNOPSIS...A STRONG STORM SYSTEM WILL MOVE INTO CENTRAL LOWER MICHIGAN TONIGHT. WIDESPREAD PRECIPITATION WILL OVERSPREAD THE REGION RESULTING IN POTENTIAL HEAVY RAIN AND SNOW. THIS STORM SYSTEM WILL EXIT THE REGION TUESDAY WHILE COLD AIR AND STRONG WINDS PLOW INTO ALL OF MICHIGAN. HIGH PRESSURE WILL THEN SETTLE IN WEDNESDAY WITH SEASONABLE TEMPERATURES THROUGH THE REMAINDER OF THE WEEK. DISCUSSION...SFC/RUC/SATELLITE/RADAR AND UPPER AIR ANALYSIS SHOWING SHORTWAVE TROUGH LIFTING OUT OF THE ROCKIES WHILE SFC LOW PRESSURE IS DEEPENING OVER NRN MO/SRN IOWA AS IT CONTINUES TO LIFT NORTHEAST. STORMS HAVE FIRED ALONG THE COLD FRONT WHICH WAS DRAPED FROM THE LOW...TO MO/AR/OK. THIS IS SEEMINGLY ROBBING US OF SOME OF THE DEEPEST MOISTURE TO THE SOUTH. TEMPERATURES HAVE BEEN VERY SLOW TO CLIMB...AS WARM FRONT REMAINS TO THE SOUTH OF US...AND AN EASTERLY FLOW OFF THE LAKE HAS KEPT READINGS IN THE 30S. INITIAL SHORTWAVE WORKING INTO THE WESTERN GREAT LAKES AND WAS RESULTING IN EXPANDING RAIN SHIELD SPREADING INTO NRN MICHIGAN. TONIGHT...SFC OW WILL WORK INTO CENTRAL LOWER TONIGHT AND STRONGEST H7-H5 -DIVQ SPREADS IN ACROSS UPPER MICHIGAN WITH A SECOND AREA ACROSS SRN LOWER THIS EVENING. THIS FORCING COMBINED WITH H3-H2 UPPER DIVERGENCE ASSOCIATED WITH STRONG UPPER JET OF 120KTS AND STRONG AND DEEP FGEN RESPONSE SUGGESTIVE OF ENHANCED BANDED PRECIPITATION. MODEL CROSS SECTIONS SHOW THE STRONG SLOPED FRONTAL SURFACE WITH -EPV AND BULLSEYE OF LIFT CENTERED OVER PLN. AREA TAMDAR SOUNDINGS ARE SUPPORTING NAM/GFS SOUNDINGS OF MAINLY A SNOW EVENT ACROSS CHIPPEWA COUNTY...MIXED SNOW AND SLEET ACROSS MAINLY MACKINAC COUNTY...AND ALL RAIN FOR PRETTY MUCH ALL OF NRN LOWER MICHIGAN. THERE IS A +1.5C SWATCH OF AIR THROUGH 3KFT ACROSS CIU...BUT WITH A BIT OF DRY AIR BELOW THIS (CIGS 6KFT)...EVAP COOLING SHOULD ALLOW ANY ONSET OF RAIN...TO SWITCH OVER TO SNOW RATHER QUICKLY. THIS ESPECIALLY TRUE IN THE PRESENCE OF SUCH STRONG VERTICAL MOTIONS THAT ARE EXPECTED. OVERALL...STILL SEE POTENTIALLY 10 INCHES OF SNOW NEAR PARADISE TAPERING OFF RATHER QUICKLY TO MAYBE A COUPLE OF INCHES NEARER TO DRUMMOND ISLAND. CONVECTIVE ACTIVITY COULD ALLOW FOR SNOW TO MIX IN WITH RAIN ACROSS PORTIONS OF FAR NRN LOWER...BUT AGAIN...MAINLY RAIN EXPECTED. FINALLY...LOOK FOR STRONG WINDS TO DEVELOP LATE TONIGHT ACROSS WHITEFISH BAY AS LOW PASSES EAST AND COLD AIR STARTS TO WORK INTO FAR WESTERN CHIP/MACK. COULD SEE GUSTS TO 35 MPH DEVELOP LATE...AND QUITE POSSIBLY ACROSS WHITEFISH BAY THIS EVENING TOO. THE STRONG WINDS WILL DEVELOP OVER ALL OF NRN MICHIGAN TUESDAY. TEMPERATURES WILL ACTUALLY RISE OVERNIGHT IN AREAS SOUTH OF M-32 AS WARM FRONT LIFTS NORTH OF THIS AREA. THERE IS A CHANCE THAT GUSTY WINDS COULD DEVELOP NEAR THE BAY...BUT GOING INTO NIGHT TIME...DO NOT SEE WHERE DEEP ENOUGH MIXING COULD MAKE THIS A FACTOR. WILL HAVE READINGS RISING INTO THE MIDDLE 40S FOR THESE AREAS...WHILE TEMPERATURES REMAIN NEARLY STEADY IN THE 30S OR SLOWLY FALL (EASTERN UPPER). SMD TUESDAY...THE STORM SYSTEM WILL BE LOCATED BETWEEN SAGINAW BAY AND ALPENA ALONG THE LAKE HURON SHORELINE AT 12Z...EXITING QUICKLY TO THE NORTHEAST OF LAKE HURON DURING THE AFTERNOON. ADDITIONAL LIFT TUESDAY...WILL BE FROM A 500MB TROUGH SWEEPING OVER THE GREAT LAKES REGION DURING THE DAY. THIS TROUGH IS ALSO EXPECTED TO MOVE EAST OF LAKE HURON BY THE AFTERNOON. 850-700MB FRONTOGENESIS SHOWS THE BEST LIFT WITH THE EXITING SFC LOW...TO REMAIN OVER THE STRAITS AND EAST UPPER MICHIGAN...MAINLY INTO THE AFTERNOON BEFORE DIMINISHING BY EVENING. MODEL SOUNDINGS FROM THE STRAITS NORTH...SHOW ABUNDANT MSTR FROM THE SFC THROUGH 500MB...WITH AN ENTIRE SOUNDING BELOW FREEZING. QPF FORECAST WOULD SUGGEST ANOTHER 3 TO 5 INCHES POSSIBLE IN THE REGION INTO THE AFTERNOON...THEREFORE WILL LEAVE WINTER STORM WARNING IN EFFECT FOR EAST UPPER. FOR NORTHERN LOWER MICHIGAN LOCATIONS WEST OF I-75...SOUNDINGS SHOW SOME MIX POSSIBLE FIRST THING IN THE MORNING QUICKLY BECOMING SNOW...THEN POSSIBLE DRIZZLE IN THE AFTERNOON AS MID AND UPPER LVL MSTR STRIPS OUT. FOR THE REST OF NRN LOWER MICHIGAN...850MB WET BULBS WILL BE ABOVE ZERO IN THE MORNING DROPPING BELOW ZERO IN THE AFTERNOON. THEREFORE WILL CONTINUE A CHANCE OF RAIN/DRIZZLE IN THE MORNING...BEFORE BECOMING LIGHT SNOW IN THE AFTERNOON. WILL HAVE GALE WARNINGS OVER NRN MICHIGAN NEARSHORES IN EFFECT THROUGH TUESDAY AFTERNOON...AS WIND GUSTS BEHIND THE EXITING FRONT INCREASE TO BTW 35 AND 40KTS. WILL CONTINUE GALE WARNINGS INTO THE EARLY EVENING BEFORE WINDS DIMINISH WITH INCREASE HIGH PRESSURE. THE STRONG WINDS WILL ALSO RESULT IN BLOWING AND DRIFTING SNOW ACROSS EASTERN UPPER THAT COULD POTENTIALLY RESULT IN SIGNIFICANTLY REDUCED VISIBILITIES. TUESDAY NIGHT...A STRONG AREA OF HIGH PRESSURE WILL BUILD BACK INTO THE WRN LAKES FROM THE UPPER MIDWEST EARLY TUESDAY EVENING... ACCOMPANIED BY 500MB ZONAL FLOW ALOFT. MODEL SOUNDINGS AND MSTR PROGS SHOWING DRYING CONDS MOVING OVER THE GREAT LAKES REGION QUICKLY DURING THE EVENING...DROPPING TO AROUND 30 PCT BETWEEN 850-500 AROUND 00Z WED. OVERALL WILL MAINTAIN THE DRY CONDITIONS OVER THE FORECAST. HOWEVER WILL MENTION SOME EARLY EVENING LAKE INDUCED SNOW SHOWERS OVER PORTIONS OF NORTHWEST LOWER AND EAST UPPER MICHIGAN. 850 MB TEMPS ARE PROGGED AROUND -12C...WITH NRN LAKE MI WATER TEMPS NEAR +1C. 925-850 MB WINDS WILL BE FROM THE NORTHWEST WITH 900-700 MB RH ARND 80 PCT...QUICKLY DRYING TO UNDER 30 PCT BY 06Z. MODEL SOUNDINGS SHOW AN INVERSION HEIGHT AROUND 5K FT AROUND 00Z...QUICKLY DIMINISHING TO UNDER 3500FT BY 06Z. SNOWFALL AMOUNTS WILL BE UNDER ONE INCH...AS LW LVL MSTR DOES NOT EXTEND UP MUCH PASS -11C DURING THIS PERIOD AND MODELS SHOW DRY AIR QUICKLY MOVING BACK IN. WEDNESDAY/WEDNESDAY NIGHT...A LARGE AREA OF HIGH PRESSURE IS PROGGED TO MOVE OVER THE UPPER MIDWEST WEDNESDAY MORNING...BECOMING CENTERED OVER THE REGION IN THE AFTERNOON. THE HIGH IS FORECAST TO MOVE EAST ONTO THE MID ATLANTIC COAST BY 12Z THURSDAY...HOWEVER SFC RIDGING IS FORECAST TO LINGER OVER THE GREAT LAKES REGION INTO THURSDAY. AT UPPER LEVELS 500 MB...APPEARS TO BE ZONAL THRU THE PERIOD WITH A WEAK UPPER TROUGH SLIDING INTO THE WRN LAKES REGION THURSDAY MORNING. OVERALL WILL CONTINUE WITH DRY CONDS WED AND WED NIGHT. HIGH TEMPERATURES...WITH AT LEAST PARTIAL SUNSHINE AND 850 MB TEMPS RUNNING AROUND -4C...WOULD SUGGEST HIGH TEMPERATURES FROM AROUND 40 OVER EAST UPPER MICHIGAN TO THE MID 40S OVER THE SOUTHERN PORTIONS OF THE FORECAST AREA. WILL MENTION OVERNIGHT LOWS FALLING BACK TO NEARLY NORMAL IN THE MID 20S...AS SKIES SHOULD REMAIN FAIRLY CLEAR OVERNIGHT. THURSDAY...HIGH PRESSURE RIDGING STILL THE DOMINATE FEATURE OVER THE GREAT LAKES THRU MUCH OF THE PERIOD...WHILE THE UPPER LEVELS REMAIN FAIRLY ZONAL THRU THE AFTN. OVERALL WILL MENTION PARTLY SUNNY SKIES AND DRY CONDITIONS THROUGH THE DAY. AFTERNOON HIGHS SHOULD ONCE AGAIN BE IN THE MID 40S WITH 850 MB TEMPS AROUND -3C AND SOME SUN...AND POSSIBLY LESS SNOW COVER. WILL KEEP THE MENTION OF A CHANCE OF PCPN OVER THE SOUTHEAST CWA THURSDAY NIGHT AS A SHORT WAVE TROUGH MOVES OVER THE UPPER MIDWEST AND WRN LAKES REGION. THIS WILL COMBINE WITH A STORM SYSTEM PROGGED TO MOVE ONCE AGAIN INTO THE OHIO VALLEY. WILL MENTION THIS PCPN AS MAINLY SNOW AS OVERNIGHT LOWS FALL INTO THE MID 20S...ALONG WITH BEING WELL NORTH OF THE OHIO VALLEY STORM SYSTEM. FRIDAY THRU MONDAY...UPPER LEVEL PATTERN SHOWING NEARLY ZONAL FLOW ACRS THE UPPER LAKES FRIDAY THROUGH SATURDAY. PATTERN AT THE SFC A LITTLE LESS ORGANIZED AND NON-DISTINCT...WITH WEAK HIGH PRESSURE OVER THE REGION THRU SATURDAY WHILE A STORM SYSTEM REMAINS OVER HUDSON BAY. 850MB TEMP PATTERN REMAINS THE SAME...GENERALLY HANGING AROUND -3C TO -4C WHICH SHOULD GENERATE TEMPS IN THE MID 40S ACROSS MUCH OF NRN LOWER WITH LOWER 40S OVER EAST UPPER. THE SRN PORTIONS OF THE FORECAST AREA SHOULD BEGIN WARMING QUITE EFFICIENTLY THIS WEEKEND AS SNOW LINE CONTINUES TO SLOWLY MOVE NORTH. WILL MENTION A CHANCE OF PCPN SUNDAY...AS UPPER TROUGH STRENGTHENS OVER THE UPPER LAKES...FROM A LOW CENTERED OVER HUDSON BAY. THE SFC RESPONSE IS A WEAK BOUNDARY PROGGED TO MOVE OVER THE STATE SUNDAY...WITH HIGH PRESSURE PROGGED TO MOVE BACK OVER THE STATE SUNDAY NIGHT AND MONDAY. WILL KEEP THE FORECAST AREA DRY MONDAY WITH THE RIDGE OF HIGH PRESSURE MOVING OVER THE WRN LAKES...WILL MENTION WARMER HIGHS FOR THE SRN CWA DUE TO LACK OF SNOW BY THAT TIME AND POTENTIAL FOR SUN. SWR AVIATION... && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WARNING UNTIL 5 PM EDT TUESDAY FOR MIZ008-015. LM...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LMZ323-341-342- 344>346. LH...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LHZ345>349. LS...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LSZ322. GALE WARNING UNTIL 11 PM EDT TUESDAY FOR LSZ321. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
938 PM EDT MON MAR 31 2008 .UPDATE...AM IN THE PROCESS OF TAKING SOME OF THE THUNDER OUT OF THE FORECAST, AS THE MIDLEVEL DRY SLOT LOOKS TO BE MOVING INTO THE REGION PUTTING A CAP ON THE THUNDER AND MOST OF THE RAIN. NORTH OF THE WARM FRONT THE F-GEN LOOKS TO BE GENERATING MORE RAIN, SNOW AND SLEET IN C AND E UPPER. THERE IS EVEN SOME THUNDER NORTH OF THE FRONT. SO HAVE UPDATED THE ZONES TO TAKE SOME OF THE THUNDER OUT, BUT IT LOOKS LIKE THAT THE THUNDER NEEDS TO BE TAKEN OUT OF THE FORECAST FOR AN AREA SOUTH OF A LINE FROM TVC TO APN AT THE LEAST. WILL PROBABLY HAVE ANOTHER UPDATE OUT SOON. LUTZ && .PREV DISCUSSION... /ISSUED 436 PM EDT MON MAR 31 2008/ SYNOPSIS...A STRONG STORM SYSTEM WILL MOVE INTO CENTRAL LOWER MICHIGAN TONIGHT. WIDESPREAD PRECIPITATION WILL OVERSPREAD THE REGION RESULTING IN POTENTIAL HEAVY RAIN AND SNOW. THIS STORM SYSTEM WILL EXIT THE REGION TUESDAY WHILE COLD AIR AND STRONG WINDS PLOW INTO ALL OF MICHIGAN. HIGH PRESSURE WILL THEN SETTLE IN WEDNESDAY WITH SEASONABLE TEMPERATURES THROUGH THE REMAINDER OF THE WEEK. DISCUSSION...SFC/RUC/SATELLITE/RADAR AND UPPER AIR ANALYSIS SHOWING SHORTWAVE TROUGH LIFTING OUT OF THE ROCKIES WHILE SFC LOW PRESSURE IS DEEPENING OVER NRN MO/SRN IOWA AS IT CONTINUES TO LIFT NORTHEAST. STORMS HAVE FIRED ALONG THE COLD FRONT WHICH WAS DRAPED FROM THE LOW...TO MO/AR/OK. THIS IS SEEMINGLY ROBBING US OF SOME OF THE DEEPEST MOISTURE TO THE SOUTH. TEMPERATURES HAVE BEEN VERY SLOW TO CLIMB...AS WARM FRONT REMAINS TO THE SOUTH OF US...AND AN EASTERLY FLOW OFF THE LAKE HAS KEPT READINGS IN THE 30S. INITIAL SHORTWAVE WORKING INTO THE WESTERN GREAT LAKES AND WAS RESULTING IN EXPANDING RAIN SHIELD SPREADING INTO NRN MICHIGAN. TONIGHT...SFC OW WILL WORK INTO CENTRAL LOWER TONIGHT AND STRONGEST H7-H5 -DIVQ SPREADS IN ACROSS UPPER MICHIGAN WITH A SECOND AREA ACROSS SRN LOWER THIS EVENING. THIS FORCING COMBINED WITH H3-H2 UPPER DIVERGENCE ASSOCIATED WITH STRONG UPPER JET OF 120KTS AND STRONG AND DEEP FGEN RESPONSE SUGGESTIVE OF ENHANCED BANDED PRECIPITATION. MODEL CROSS SECTIONS SHOW THE STRONG SLOPED FRONTAL SURFACE WITH -EPV AND BULLSEYE OF LIFT CENTERED OVER PLN. AREA TAMDAR SOUNDINGS ARE SUPPORTING NAM/GFS SOUNDINGS OF MAINLY A SNOW EVENT ACROSS CHIPPEWA COUNTY...MIXED SNOW AND SLEET ACROSS MAINLY MACKINAC COUNTY...AND ALL RAIN FOR PRETTY MUCH ALL OF NRN LOWER MICHIGAN. THERE IS A +1.5C SWATCH OF AIR THROUGH 3KFT ACROSS CIU...BUT WITH A BIT OF DRY AIR BELOW THIS (CIGS 6KFT)...EVAP COOLING SHOULD ALLOW ANY ONSET OF RAIN...TO SWITCH OVER TO SNOW RATHER QUICKLY. THIS ESPECIALLY TRUE IN THE PRESENCE OF SUCH STRONG VERTICAL MOTIONS THAT ARE EXPECTED. OVERALL...STILL SEE POTENTIALLY 10 INCHES OF SNOW NEAR PARADISE TAPERING OFF RATHER QUICKLY TO MAYBE A COUPLE OF INCHES NEARER TO DRUMMOND ISLAND. CONVECTIVE ACTIVITY COULD ALLOW FOR SNOW TO MIX IN WITH RAIN ACROSS PORTIONS OF FAR NRN LOWER...BUT AGAIN...MAINLY RAIN EXPECTED. FINALLY...LOOK FOR STRONG WINDS TO DEVELOP LATE TONIGHT ACROSS WHITEFISH BAY AS LOW PASSES EAST AND COLD AIR STARTS TO WORK INTO FAR WESTERN CHIP/MACK. COULD SEE GUSTS TO 35 MPH DEVELOP LATE...AND QUITE POSSIBLY ACROSS WHITEFISH BAY THIS EVENING TOO. THE STRONG WINDS WILL DEVELOP OVER ALL OF NRN MICHIGAN TUESDAY. TEMPERATURES WILL ACTUALLY RISE OVERNIGHT IN AREAS SOUTH OF M-32 AS WARM FRONT LIFTS NORTH OF THIS AREA. THERE IS A CHANCE THAT GUSTY WINDS COULD DEVELOP NEAR THE BAY...BUT GOING INTO NIGHT TIME...DO NOT SEE WHERE DEEP ENOUGH MIXING COULD MAKE THIS A FACTOR. WILL HAVE READINGS RISING INTO THE MIDDLE 40S FOR THESE AREAS...WHILE TEMPERATURES REMAIN NEARLY STEADY IN THE 30S OR SLOWLY FALL (EASTERN UPPER). SMD TUESDAY...THE STORM SYSTEM WILL BE LOCATED BETWEEN SAGINAW BAY AND ALPENA ALONG THE LAKE HURON SHORELINE AT 12Z...EXITING QUICKLY TO THE NORTHEAST OF LAKE HURON DURING THE AFTERNOON. ADDITIONAL LIFT TUESDAY...WILL BE FROM A 500MB TROUGH SWEEPING OVER THE GREAT LAKES REGION DURING THE DAY. THIS TROUGH IS ALSO EXPECTED TO MOVE EAST OF LAKE HURON BY THE AFTERNOON. 850-700MB FRONTOGENESIS SHOWS THE BEST LIFT WITH THE EXITING SFC LOW...TO REMAIN OVER THE STRAITS AND EAST UPPER MICHIGAN...MAINLY INTO THE AFTERNOON BEFORE DIMINISHING BY EVENING. MODEL SOUNDINGS FROM THE STRAITS NORTH...SHOW ABUNDANT MSTR FROM THE SFC THROUGH 500MB...WITH AN ENTIRE SOUNDING BELOW FREEZING. QPF FORECAST WOULD SUGGEST ANOTHER 3 TO 5 INCHES POSSIBLE IN THE REGION INTO THE AFTERNOON...THEREFORE WILL LEAVE WINTER STORM WARNING IN EFFECT FOR EAST UPPER. FOR NORTHERN LOWER MICHIGAN LOCATIONS WEST OF I-75...SOUNDINGS SHOW SOME MIX POSSIBLE FIRST THING IN THE MORNING QUICKLY BECOMING SNOW...THEN POSSIBLE DRIZZLE IN THE AFTERNOON AS MID AND UPPER LVL MSTR STRIPS OUT. FOR THE REST OF NRN LOWER MICHIGAN...850MB WET BULBS WILL BE ABOVE ZERO IN THE MORNING DROPPING BELOW ZERO IN THE AFTERNOON. THEREFORE WILL CONTINUE A CHANCE OF RAIN/DRIZZLE IN THE MORNING...BEFORE BECOMING LIGHT SNOW IN THE AFTERNOON. WILL HAVE GALE WARNINGS OVER NRN MICHIGAN NEARSHORES IN EFFECT THROUGH TUESDAY AFTERNOON...AS WIND GUSTS BEHIND THE EXITING FRONT INCREASE TO BTW 35 AND 40KTS. WILL CONTINUE GALE WARNINGS INTO THE EARLY EVENING BEFORE WINDS DIMINISH WITH INCREASE HIGH PRESSURE. THE STRONG WINDS WILL ALSO RESULT IN BLOWING AND DRIFTING SNOW ACROSS EASTERN UPPER THAT COULD POTENTIALLY RESULT IN SIGNIFICANTLY REDUCED VISIBILITIES. TUESDAY NIGHT...A STRONG AREA OF HIGH PRESSURE WILL BUILD BACK INTO THE WRN LAKES FROM THE UPPER MIDWEST EARLY TUESDAY EVENING... ACCOMPANIED BY 500MB ZONAL FLOW ALOFT. MODEL SOUNDINGS AND MSTR PROGS SHOWING DRYING CONDS MOVING OVER THE GREAT LAKES REGION QUICKLY DURING THE EVENING...DROPPING TO AROUND 30 PCT BETWEEN 850-500 AROUND 00Z WED. OVERALL WILL MAINTAIN THE DRY CONDITIONS OVER THE FORECAST. HOWEVER WILL MENTION SOME EARLY EVENING LAKE INDUCED SNOW SHOWERS OVER PORTIONS OF NORTHWEST LOWER AND EAST UPPER MICHIGAN. 850 MB TEMPS ARE PROGGED AROUND -12C...WITH NRN LAKE MI WATER TEMPS NEAR +1C. 925-850 MB WINDS WILL BE FROM THE NORTHWEST WITH 900-700 MB RH ARND 80 PCT...QUICKLY DRYING TO UNDER 30 PCT BY 06Z. MODEL SOUNDINGS SHOW AN INVERSION HEIGHT AROUND 5K FT AROUND 00Z...QUICKLY DIMINISHING TO UNDER 3500FT BY 06Z. SNOWFALL AMOUNTS WILL BE UNDER ONE INCH...AS LW LVL MSTR DOES NOT EXTEND UP MUCH PASS -11C DURING THIS PERIOD AND MODELS SHOW DRY AIR QUICKLY MOVING BACK IN. WEDNESDAY/WEDNESDAY NIGHT...A LARGE AREA OF HIGH PRESSURE IS PROGGED TO MOVE OVER THE UPPER MIDWEST WEDNESDAY MORNING...BECOMING CENTERED OVER THE REGION IN THE AFTERNOON. THE HIGH IS FORECAST TO MOVE EAST ONTO THE MID ATLANTIC COAST BY 12Z THURSDAY...HOWEVER SFC RIDGING IS FORECAST TO LINGER OVER THE GREAT LAKES REGION INTO THURSDAY. AT UPPER LEVELS 500 MB...APPEARS TO BE ZONAL THRU THE PERIOD WITH A WEAK UPPER TROUGH SLIDING INTO THE WRN LAKES REGION THURSDAY MORNING. OVERALL WILL CONTINUE WITH DRY CONDS WED AND WED NIGHT. HIGH TEMPERATURES...WITH AT LEAST PARTIAL SUNSHINE AND 850 MB TEMPS RUNNING AROUND -4C...WOULD SUGGEST HIGH TEMPERATURES FROM AROUND 40 OVER EAST UPPER MICHIGAN TO THE MID 40S OVER THE SOUTHERN PORTIONS OF THE FORECAST AREA. WILL MENTION OVERNIGHT LOWS FALLING BACK TO NEARLY NORMAL IN THE MID 20S...AS SKIES SHOULD REMAIN FAIRLY CLEAR OVERNIGHT. THURSDAY...HIGH PRESSURE RIDGING STILL THE DOMINATE FEATURE OVER THE GREAT LAKES THRU MUCH OF THE PERIOD...WHILE THE UPPER LEVELS REMAIN FAIRLY ZONAL THRU THE AFTN. OVERALL WILL MENTION PARTLY SUNNY SKIES AND DRY CONDITIONS THROUGH THE DAY. AFTERNOON HIGHS SHOULD ONCE AGAIN BE IN THE MID 40S WITH 850 MB TEMPS AROUND -3C AND SOME SUN...AND POSSIBLY LESS SNOW COVER. WILL KEEP THE MENTION OF A CHANCE OF PCPN OVER THE SOUTHEAST CWA THURSDAY NIGHT AS A SHORT WAVE TROUGH MOVES OVER THE UPPER MIDWEST AND WRN LAKES REGION. THIS WILL COMBINE WITH A STORM SYSTEM PROGGED TO MOVE ONCE AGAIN INTO THE OHIO VALLEY. WILL MENTION THIS PCPN AS MAINLY SNOW AS OVERNIGHT LOWS FALL INTO THE MID 20S...ALONG WITH BEING WELL NORTH OF THE OHIO VALLEY STORM SYSTEM. FRIDAY THRU MONDAY...UPPER LEVEL PATTERN SHOWING NEARLY ZONAL FLOW ACRS THE UPPER LAKES FRIDAY THROUGH SATURDAY. PATTERN AT THE SFC A LITTLE LESS ORGANIZED AND NON-DISTINCT...WITH WEAK HIGH PRESSURE OVER THE REGION THRU SATURDAY WHILE A STORM SYSTEM REMAINS OVER HUDSON BAY. 850MB TEMP PATTERN REMAINS THE SAME...GENERALLY HANGING AROUND -3C TO -4C WHICH SHOULD GENERATE TEMPS IN THE MID 40S ACROSS MUCH OF NRN LOWER WITH LOWER 40S OVER EAST UPPER. THE SRN PORTIONS OF THE FORECAST AREA SHOULD BEGIN WARMING QUITE EFFICIENTLY THIS WEEKEND AS SNOW LINE CONTINUES TO SLOWLY MOVE NORTH. WILL MENTION A CHANCE OF PCPN SUNDAY...AS UPPER TROUGH STRENGTHENS OVER THE UPPER LAKES...FROM A LOW CENTERED OVER HUDSON BAY. THE SFC RESPONSE IS A WEAK BOUNDARY PROGGED TO MOVE OVER THE STATE SUNDAY...WITH HIGH PRESSURE PROGGED TO MOVE BACK OVER THE STATE SUNDAY NIGHT AND MONDAY. WILL KEEP THE FORECAST AREA DRY MONDAY WITH THE RIDGE OF HIGH PRESSURE MOVING OVER THE WRN LAKES...WILL MENTION WARMER HIGHS FOR THE SRN CWA DUE TO LACK OF SNOW BY THAT TIME AND POTENTIAL FOR SUN. SWR AVIATION... && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WARNING UNTIL 5 PM EDT TUESDAY FOR MIZ008-015. LM...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LMZ323-341-342- 344>346. LH...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LHZ345>349. LS...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LSZ322. GALE WARNING UNTIL 11 PM EDT TUESDAY FOR LSZ321. && $$
AREA FORECAST DISCUSSION...UPDATE
NWS MARQUETTE MI
725 PM EDT MON MAR 31 2008 ...LATE SEASON WINTER STORM MOVING INTO UPPER MICHIGAN WITH BLIZZARD CONDITIONS POSSIBLE OVER THE NORTH CENTRAL TUE MORNING... ...TRAVEL STRONGLY DISCOURAGED THROUGH TUE MORNING... .UPDATE... ADDED MENTION OF ELEVATED TS TO SRN MNM COUNTY IN ADVANCE OF CLUSTER OF CNVCTN MOVING NE THRU CNTRL WI WHERE 18Z NAM F6 SHOWS H7-5 LAPSE RATES APRCHG 7C/KM JUST TO THE N OF H85 WARM FNT. && .SYNOPSIS... 20Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED UPPER LEVEL TROUGHING OVER THE NORTHWEST U.S. INTO THE NRN PLAINS AND STRONG RIDGING ALONG THE EAST COAST. WITHIN THE TROUGH...TWO MAIN FEATURES ARE EVIDENT FOR THE WINTER STORM. FIRST IS A SHRTWV OVER ERN NEBRASKA AND THE SECOND IS AN UPPER LEVEL LOW OVER RIVERTON WY. DPVA AHEAD OF THE ERN NEBRASKA SHRTWV...STRONG WARM ADVECTION OF MOISTURE INTO THE UPPER MIDWEST (PRECIPITABLE WATER VALUES NEAR 200 PCT OF NORMAL PER 12Z RAOBS)...AND UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 130 KT JET STRETCHING FROM NE MN INTO NORTHERN ONTARIO...HAS LED TO THE DEVELOPMENT OF A DEFORMATION ZONE OF MOSTLY LIGHT TO MODERATE PCPN FROM CENTRAL/SRN MN THROUGH MUCH OF WI AND NOW INTO THE WI BORDER AREAS. WITHIN THIS ZONE...THERE IS A POCKET OF HEAVIER PCPN WHICH HAS BEEN WELL ADVERTISED NEAR WAUSUA MOVING NE. SOME LIGHTNING HAS EVEN BEEN DETECTED WITHIN THIS HEAVIER PCPN. RAIN/SNOW/SLEET LINE IS SITUATED FROM ROCHESTER MN TO JUST SOUTH OF WAUSAU AND INTO SRN MENOMINEE COUNTY. RECENT CALLS HAVE FOUND RAIN IN MENOMINEE AND ESCANABA. SURFACE LOW ASSOCIATED WITH ALL THIS PCPN CURRENTLY NEAR INDIANOLA IA WITH A PRESSURE AROUND 999MB. COMPARISON WITH MODEL DATA APPEARS THAT THE NAM MAY BE DOING A BETTER JOB WITH THE STRENGTH COMPARED TO THE GFS. TO THE NORTHWEST...1030MB HIGH PRESSURE IS SITUTATED OVER MANITOBA. 850MB TEMPS ARE SOMEWHAT COLD AHEAD OF THIS HIGH...WITH 12Z RAOBS SHOWING -7C AT INL AND -10C AT CWPL...SO THERE IS SOME COLDER AIR TO FILTER INTO THE AREA. OVER THE CWA...SNOW HELD OFF FOR MUCH OF THE MORNING AND EARLY AFTERNOON DUE TO DRY AIR IN THE 700-900MB LAYER AS SEEN ON TAMDAR SOUNDINGS (DEWPOINT DEPRESSIONS AROUND 10C). && .SHORT TERM (TONIGHT AND TUE)... MODELS ARE NOW IN GOOD AGREEMENT WITH REGARDS TO THE TRACK OF THE LOW PRESSURE SYSTEM AS IT LIFTS ACROSS NORTHERN LAKE HURON TUE MORNING. AFTER NOTICING THAT THE GFS IS A BIT TOO WEAK WITH THE SYSTEM CURRENTLY FOR ONLY A 6 HOUR FORECAST...HAVE FOLLOWED A BIT CLOSER THE 12Z NAM/LOCAL WRF-ARW/RUC 13 MODELS WHICH ARE SLIGHTLY DEEPER. SHOULD NOTE THAT THE NEW 18Z NAM LOOKS EVEN BETTER WITH THE CURRENT STRENGTH...AND DISPLAYS EVEN MORE PCPN FOR THE CWA THAN THE GOING FORECAST. DETAILS...SHRTWV OVER ERN NEBRASKA WILL CONTINUE LIFTING NORTHEAST TONIGHT. HOWEVER...THE UPPER LOW OVER WYOMING IS PROGGED TO CATCH UP WITH THIS SHRTWV...RESULTING IN A PHASING OF THE TWO FEATURES BASICALLY OVER THE CWA AROUND 12Z. THIS PHASING WILL CAUSE THE LOW TO DEEPEN MORE AFTER 06Z...TO SOMEWHERE AROUND 993MB OVER NRN LK HURON BY 12Z TUE. UNTIL THE PHASING OCCURS...THERE ARE TWO PERIODS OF CONCERN. FOR LATE THIS AFTERNOON AND EVENING...DEFORMATION ZONE WILL ENVELOP MUCH OF UPPER MICHIGAN BY 22Z AS THE STRONG 700-600MB FRONTOGENESIS ZONE AND UPPER JET SHIFT EAST. AREA OF HVY PCPN LIKELY TO GO ACROSS THE SOUTH CENTRAL U.P.. A REPORT OF AN INCH PER HOUR CAME IN FROM MARSHFIELD AND 2 INCHES PER HOUR IN WAUSAU...AND THIS SHOULD EASILY OCCUR IN NORTHERN MENOMINEE COUNTY WHERE SOUNDING PROFILES ARE SHOWN TO STAY SOLIDLY BELOW FREEZING. IN SRN MENOMINEE COUNTY AND OTHER AREAS ALONG LAKE MICHIGAN UP INTO LUCE COUNTY... SOUNDINGS ARE A LITTLE LESS CERTAIN...WITH SNOW...SLEET OR RAIN ALL POSSIBLE. THERE WAS A REPORT OF SLEET ACCUMULATING ON THE GROUND AT WAUSAU...SO WOULD NOT BE SURPRISED TO SEE THE SAME IN SRN MENOMINEE COUNTY. OVER THE REST OF THE CWA...SNOWFALL ACCUMULATION RATES OF ONE HALF OF AN INCH TO AN INCH PER HOUR SEEM LIKELY UNDER THE DEFORMATION ZONE. THUS...GOING WARNINGS LOOK FINE. AFTER MIDNIGHT...THE UPPER JET FORCING EXITS...BUT THE PHASING BEGINS TO OCCUR. PV AND THETA-E PLOTS ACTUALLY SUGGEST THE DEVELOPMENT OF THE FULL-FLEDGED TROWAL TOWARDS LATE IN THE NIGHT...WHICH SHOULD HELP KEEP SOME LIGHT TO MODERATE BANDED PCPN GOING OVER THE CWA. COMBINE THIS WITH COLD ADVECTION ON THE BACK SIDE OF THE LOW AND A GOOD SETUP IS IN PLACE FOR LAKE ENHANCEMENT/UPSLOPE. WITH WINDS OUT OF THE NORTH TO NORTHEAST...AND STRONG AT THAT (900MB WINDS PROGGED AT 50 KT BY 12Z)...UPSLOPE SHOULD BE REALLY STRONG OVER THE HIGHER TERRAIN OF THE FAR WEST AND NORTH CENTRAL. TIMING OF THE BEST SNOW...BASED ON 900MB TEMPS THAT CORRELATED WELL WITH THE APRIL 4 2007 BLIZZARD (AROUND -8C TO START UPSLOPE) SUGGESTS BETWEEN 06-09Z OUT WEST AND 09-12Z OVER THE NORTH CENTRAL. WOULD NOT BE SURPRISED TO SEE INCH PER HOUR RATES... ESPECIALLY SINCE THE SNOW TO WATER RATIOS WILL BE HIGHER THANKS TO THE COLDER AIR. MAY HAVE TO WATCH FOR POTENTIAL FOR WINDS REACHING HIGH WIND WARNING CRITERIA TUE MORNING IN THE NORTH CENTRAL AS WELL...ESPEICALLY IF THE 18Z NAM PANS OUT. PCPN WILL DIMINISH WEST TO EAST ON TUE AS THE PHASED UPPER TROUGH MOVES AWAY FROM THE CWA...ALLOWING DRIER AIR AND SUBSIDENCE TO MOVE IN. QPF AMOUNTS FOLLOW A BLEND OF THE 12Z NAM...REGIONAL CANADIAN AND LOCAL WRF-ARW. NEW 18Z NAM IS EVEN HEAVIER WITH THE QPF...WHICH MIGHT NOT BE OUT OF THE QUESTION WITH THE SNOW REALLY INTENSIFYING OVER THE MINNEAPOLIS AREA. THE UPSLOPE IS VERY IMPRESSIVE OFF THE 18Z NAM AS WELL (TOTAL QPF OF 2.24 INCHES AT OUR OFFICE). TEMPS FOR TONIGHT AND TOMORROW LOOK REASONABLE AND VERY LITTLE MODIFICATION MADE. .LONG TERM... (TUE NIGHT THRU MON) QUIET NIGHT EXPECTED TUE NIGHT AS SFC HIGH PRES MOVES FROM THE UPPER MISSISSIPPI VALLEY INTO THE GREAT LAKES REGION. IT WILL NOT BE AN IDEAL RADIATIONAL COOLING SETUP WITH CENTER OF SFC HIGH PASSING THRU SRN WI. IN ADDITION...THERE IS SOME UNCERTAINTY ON THE CLOUD SITUATION AS STRONGER WAA PATTERN TO THE NW SHOULD SEND SOME CLOUDS SE INTO UPPER MI. NONETHELESS...FRESH SNOW COVER/LIGHT WINDS AND AT LEAST SOME TIME WITH LIMITED CLOUD COVER SUGGEST GOING BLO MOS GUIDANCE AS PREVIOUS FCST HAD INDICATED. SHOULD THE NIGHT END UP MOSTLY CLEAR...TEMPS MAY SLIP BLO ZERO IN THE TYPICAL COLD SPOTS. A COUPLE OF WEAK SHORTWAVES WILL BE TRACKING THRU THE UPPER GREAT LAKES REGION WED. SINCE BEST ISENTROPIC ASCENT SLIDES BY JUST N OF UPPER MI AND THERE WILL BE A DRY AIRMASS TO OVERCOME INITIALLY... OPTED TO MAINTAIN A DRY FCST WED WITH THE EXCEPTION OF NRN LAKE SUPERIOR. NEXT SHORTWAVE TROF SWINGS THRU THE UPPER LAKES ON THU. SINCE ANTECEDENT AIRMASS WON`T BE AS DRY AS WED...ISENTROPIC ASCENT MAY BE SUFFICIENT FOR SOME -SN WITH THIS SYSTEM LATE WED NIGHT THRU THU MORNING. HAVE THUS RETAINED SLIGHT CHC POPS FOR -SN AS SHORTWAVE PASSES. FRI THRU MON...ALTHOUGH THERE ARE SIGNIFICANT MODEL DIFFERENCES WITH THE PATTERN ACROSS THE CONUS...IT APPEARS AT THE MOMENT THAT THIS SHOULD BE A RELATIVELY QUIET PERIOD OF WEATHER ACROSS THE FCST AREA. THE ECMWF DEVELOPS MUCH MORE TROFFING OVER THE WRN CONUS OVER THE WEEKEND INTO EARLY NEXT WEEK THAN THE GFS...RESULTING IN SW FLOW TAKING SHAPE INTO THE GREAT LAKES. THE GFS HAS A W TO NW FLOW INTO THE GREAT LAKES AS POLAR VORTEX OVER HUDSON BAY MAINTAINS INFLUENCE OVER THE AREA. THE GLOBAL CANADIAN OFFERS A SOLUTION BTWN THE GFS AND ECMWF. GIVEN THE DIFFERENCES...IT`S USUALLY BEST TO MAKE MINIMAL CHANGES TO PREVIOUS FCST UNTIL BETTER MODEL AGREEMENT DEVELOPS. IN THIS CASE...THE PREVIOUS FCST LINES UP REASONABLY WELL WITH THE GFS...AND THE 12Z ECMWF HAS TRENDED SOMEWHAT TOWARD THE GFS SOLUTION. SO...WILL MAINTAIN LOW POPS OVER THE WEEKEND FOR THE POSSIBILITY OF A COLD FRONT SETTLING INTO THE UPPER LAKES EARLY SAT AND THEN THE POTENTIAL FOR ANOTHER FROPA SUN. AIRMASS SHOULD BE WARM ENOUGH TO FOR MIXED PTYPES (-SN/-RA) DURING THE AFTN HRS. EXPECT A DRY DAY MON. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... ALTHOUGH THERE MAY BE PDS OF MVFR CONDITIONS AT CMX THIS EVNG... EXPECT PREDOMINANT IFR/LIFR CONDITIONS TO PERSIST INTO TUE MRNG WITH INCRSG NNE WINDS CAUSING NEAR BLIZZARD CONDITIONS AT SAW ON TUE MRNG AS LO PRES MOVES FM IA TO SE ONTARIO TUE MRNG. CONDITIONS SHOULD IMPROVE RPDLY BY LATE TUE MRNG AT CMX AND THEN IN THE AFTN AT SAW AS SFC LO PULLS TO THE NE AND DRIER AIR INVADES FM THE W. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRESSURE OVER IOWA WILL DEEPEN TONIGHT AS IT LIFTS TO NORTHERN LAKE HURON BY TUE MORNING. 35 KT GALE FORCE WINDS ARE EXPECTED TO DEVELOP ACROSS LAKE SUPERIOR THIS EVENING...THEN INTENSIFY TO 40 TO 45 KT AFTER MIDNIGHT. IT IS POSSIBLE FOR STORM FORCE WINDS TO OCCUR ON EASTERN LAKE SUPERIOR TOMORROW MORNING...BUT CONFIDENCE IS NOT HIGH ENOUGH YET TO ISSUE THE STORM WARNING. WINDS WILL COME DOWN FAIRLY QUICK TOMORROW AS THE LOW DEPARTS AND A HIGH PRESSURE RIDGE BUILDS IN. BEYOND TUE NIGHT...WINDS LOOK TO REMAIN BELOW 25 KT THROUGH THE REST OF THE FORECAST. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... BLIZZARD WARNING UNTIL 2 PM EDT TUESDAY FOR MIZ005. BLIZZARD WARNING UNTIL 5 PM EDT TUESDAY FOR MIZ006. WINTER STORM WARNING UNTIL 1 PM EDT /12 PM CDT/ TUESDAY FOR MIZ002-009-013-014-084. WINTER STORM WARNING UNTIL 5 PM EDT TUESDAY FOR MIZ007-085. WINTER STORM WARNING UNTIL 2 PM EDT TUESDAY FOR MIZ004. WINTER STORM WARNING UNTIL 7 AM CDT TUESDAY FOR MIZ010>012. SNOW AND BLOWING SNOW ADVISORY UNTIL 1 PM EDT TUESDAY FOR MIZ001-003. LAKE SUPERIOR... GALE WARNING FROM 10 PM THIS EVENING TO 8 PM EDT TUESDAY FOR LSZ267. GALE WARNING UNTIL 8 PM EDT TUESDAY FOR LSZ265-266. GALE WARNING UNTIL 2 PM EDT TUESDAY FOR LSZ264. GALE WARNING FROM 1 AM TO 2 PM EDT TUESDAY FOR LSZ248-249. GALE WARNING FROM 11 PM THIS EVENING TO 2 PM EDT TUESDAY FOR LSZ244>247. GALE WARNING UNTIL 11 AM EDT /10 AM CDT/ TUESDAY FOR LSZ240>243. GALE WARNING UNTIL 2 AM EDT TUESDAY FOR LSZ162. GALE WARNING UNTIL 8 AM EDT TUESDAY FOR LSZ263. GALE WARNING FROM 1 AM TO 6 PM EDT TUESDAY FOR LSZ250-251. LAKE MICHIGAN... GALE WARNING FROM 8 AM TO 3 PM EDT TUESDAY FOR LMZ221-248-250. && $$ UPDATE...KC SYNOPSIS/SHORT TERM...AJ LONG TERM...ROLFSON AVIATION...KC MARINE...AJ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
510 PM EDT MON MAR 31 2008 ...LATE SEASON WINTER STORM MOVING INTO UPPER MICHIGAN WITH BLIZZARD CONDITIONS POSSIBLE OVER THE NORTH CENTRAL TUE MORNING... ...TRAVEL STRONGLY DISCOURAGED THROUGH TUE MORNING... .SYNOPSIS... 20Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED UPPER LEVEL TROUGHING OVER THE NORTHWEST U.S. INTO THE NRN PLAINS AND STRONG RIDGING ALONG THE EAST COAST. WITHIN THE TROUGH...TWO MAIN FEATURES ARE EVIDENT FOR THE WINTER STORM. FIRST IS A SHRTWV OVER ERN NEBRASKA AND THE SECOND IS AN UPPER LEVEL LOW OVER RIVERTON WY. DPVA AHEAD OF THE ERN NEBRASKA SHRTWV...STRONG WARM ADVECTION OF MOISTURE INTO THE UPPER MIDWEST (PRECIPITABLE WATER VALUES NEAR 200 PCT OF NORMAL PER 12Z RAOBS)...AND UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 130 KT JET STRETCHING FROM NE MN INTO NORTHERN ONTARIO...HAS LED TO THE DEVELOPMENT OF A DEFORMATION ZONE OF MOSTLY LIGHT TO MODERATE PCPN FROM CENTRAL/SRN MN THROUGH MUCH OF WI AND NOW INTO THE WI BORDER AREAS. WITHIN THIS ZONE...THERE IS A POCKET OF HEAVIER PCPN WHICH HAS BEEN WELL ADVERTISED NEAR WAUSUA MOVING NE. SOME LIGHTNING HAS EVEN BEEN DETECTED WITHIN THIS HEAVIER PCPN. RAIN/SNOW/SLEET LINE IS SITUATED FROM ROCHESTER MN TO JUST SOUTH OF WAUSAU AND INTO SRN MENOMINEE COUNTY. RECENT CALLS HAVE FOUND RAIN IN MENOMINEE AND ESCANABA. SURFACE LOW ASSOCIATED WITH ALL THIS PCPN CURRENTLY NEAR INDIANOLA IA WITH A PRESSURE AROUND 999MB. COMPARISON WITH MODEL DATA APPEARS THAT THE NAM MAY BE DOING A BETTER JOB WITH THE STRENGTH COMPARED TO THE GFS. TO THE NORTHWEST...1030MB HIGH PRESSURE IS SITUTATED OVER MANITOBA. 850MB TEMPS ARE SOMEWHAT COLD AHEAD OF THIS HIGH...WITH 12Z RAOBS SHOWING -7C AT INL AND -10C AT CWPL...SO THERE IS SOME COLDER AIR TO FILTER INTO THE AREA. OVER THE CWA...SNOW HELD OFF FOR MUCH OF THE MORNING AND EARLY AFTERNOON DUE TO DRY AIR IN THE 700-900MB LAYER AS SEEN ON TAMDAR SOUNDINGS (DEWPOINT DEPRESSIONS AROUND 10C). && .SHORT TERM (TONIGHT AND TUE)... MODELS ARE NOW IN GOOD AGREEMENT WITH REGARDS TO THE TRACK OF THE LOW PRESSURE SYSTEM AS IT LIFTS ACROSS NORTHERN LAKE HURON TUE MORNING. AFTER NOTICING THAT THE GFS IS A BIT TOO WEAK WITH THE SYSTEM CURRENTLY FOR ONLY A 6 HOUR FORECAST...HAVE FOLLOWED A BIT CLOSER THE 12Z NAM/LOCAL WRF-ARW/RUC 13 MODELS WHICH ARE SLIGHTLY DEEPER. SHOULD NOTE THAT THE NEW 18Z NAM LOOKS EVEN BETTER WITH THE CURRENT STRENGTH...AND DISPLAYS EVEN MORE PCPN FOR THE CWA THAN THE GOING FORECAST. DETAILS...SHRTWV OVER ERN NEBRASKA WILL CONTINUE LIFTING NORTHEAST TONIGHT. HOWEVER...THE UPPER LOW OVER WYOMING IS PROGGED TO CATCH UP WITH THIS SHRTWV...RESULTING IN A PHASING OF THE TWO FEATURES BASICALLY OVER THE CWA AROUND 12Z. THIS PHASING WILL CAUSE THE LOW TO DEEPEN MORE AFTER 06Z...TO SOMEWHERE AROUND 993MB OVER NRN LK HURON BY 12Z TUE. UNTIL THE PHASING OCCURS...THERE ARE TWO PERIODS OF CONCERN. FOR LATE THIS AFTERNOON AND EVENING...DEFORMATION ZONE WILL ENVELOP MUCH OF UPPER MICHIGAN BY 22Z AS THE STRONG 700-600MB FRONTOGENESIS ZONE AND UPPER JET SHIFT EAST. AREA OF HVY PCPN LIKELY TO GO ACROSS THE SOUTH CENTRAL U.P.. A REPORT OF AN INCH PER HOUR CAME IN FROM MARSHFIELD AND 2 INCHES PER HOUR IN WAUSAU...AND THIS SHOULD EASILY OCCUR IN NORTHERN MENOMINEE COUNTY WHERE SOUNDING PROFILES ARE SHOWN TO STAY SOLIDLY BELOW FREEZING. IN SRN MENOMINEE COUNTY AND OTHER AREAS ALONG LAKE MICHIGAN UP INTO LUCE COUNTY... SOUNDINGS ARE A LITTLE LESS CERTAIN...WITH SNOW...SLEET OR RAIN ALL POSSIBLE. THERE WAS A REPORT OF SLEET ACCUMULATING ON THE GROUND AT WAUSAU...SO WOULD NOT BE SURPRISED TO SEE THE SAME IN SRN MENOMINEE COUNTY. OVER THE REST OF THE CWA...SNOWFALL ACCUMULATION RATES OF ONE HALF OF AN INCH TO AN INCH PER HOUR SEEM LIKELY UNDER THE DEFORMATION ZONE. THUS...GOING WARNINGS LOOK FINE. AFTER MIDNIGHT...THE UPPER JET FORCING EXITS...BUT THE PHASING BEGINS TO OCCUR. PV AND THETA-E PLOTS ACTUALLY SUGGEST THE DEVELOPMENT OF THE FULL-FLEDGED TROWAL TOWARDS LATE IN THE NIGHT...WHICH SHOULD HELP KEEP SOME LIGHT TO MODERATE BANDED PCPN GOING OVER THE CWA. COMBINE THIS WITH COLD ADVECTION ON THE BACK SIDE OF THE LOW AND A GOOD SETUP IS IN PLACE FOR LAKE ENHANCEMENT/UPSLOPE. WITH WINDS OUT OF THE NORTH TO NORTHEAST...AND STRONG AT THAT (900MB WINDS PROGGED AT 50 KT BY 12Z)...UPSLOPE SHOULD BE REALLY STRONG OVER THE HIGHER TERRAIN OF THE FAR WEST AND NORTH CENTRAL. TIMING OF THE BEST SNOW...BASED ON 900MB TEMPS THAT CORRELATED WELL WITH THE APRIL 4 2007 BLIZZARD (AROUND -8C TO START UPSLOPE) SUGGESTS BETWEEN 06-09Z OUT WEST AND 09-12Z OVER THE NORTH CENTRAL. WOULD NOT BE SURPRISED TO SEE INCH PER HOUR RATES... ESPECIALLY SINCE THE SNOW TO WATER RATIOS WILL BE HIGHER THANKS TO THE COLDER AIR. MAY HAVE TO WATCH FOR POTENTIAL FOR WINDS REACHING HIGH WIND WARNING CRITERIA TUE MORNING IN THE NORTH CENTRAL AS WELL...ESPEICALLY IF THE 18Z NAM PANS OUT. PCPN WILL DIMINISH WEST TO EAST ON TUE AS THE PHASED UPPER TROUGH MOVES AWAY FROM THE CWA...ALLOWING DRIER AIR AND SUBSIDENCE TO MOVE IN. QPF AMOUNTS FOLLOW A BLEND OF THE 12Z NAM...REGIONAL CANADIAN AND LOCAL WRF-ARW. NEW 18Z NAM IS EVEN HEAVIER WITH THE QPF...WHICH MIGHT NOT BE OUT OF THE QUESTION WITH THE SNOW REALLY INTENSIFYING OVER THE MINNEAPOLIS AREA. THE UPSLOPE IS VERY IMPRESSIVE OFF THE 18Z NAM AS WELL (TOTAL QPF OF 2.24 INCHES AT OUR OFFICE). TEMPS FOR TONIGHT AND TOMORROW LOOK REASONABLE AND VERY LITTLE MODIFICATION MADE. .LONG TERM... (TUE NIGHT THRU MON) QUIET NIGHT EXPECTED TUE NIGHT AS SFC HIGH PRES MOVES FROM THE UPPER MISSISSIPPI VALLEY INTO THE GREAT LAKES REGION. IT WILL NOT BE AN IDEAL RADIATIONAL COOLING SETUP WITH CENTER OF SFC HIGH PASSING THRU SRN WI. IN ADDITION...THERE IS SOME UNCERTAINTY ON THE CLOUD SITUATION AS STRONGER WAA PATTERN TO THE NW SHOULD SEND SOME CLOUDS SE INTO UPPER MI. NONETHELESS...FRESH SNOW COVER/LIGHT WINDS AND AT LEAST SOME TIME WITH LIMITED CLOUD COVER SUGGEST GOING BLO MOS GUIDANCE AS PREVIOUS FCST HAD INDICATED. SHOULD THE NIGHT END UP MOSTLY CLEAR...TEMPS MAY SLIP BLO ZERO IN THE TYPICAL COLD SPOTS. A COUPLE OF WEAK SHORTWAVES WILL BE TRACKING THRU THE UPPER GREAT LAKES REGION WED. SINCE BEST ISENTROPIC ASCENT SLIDES BY JUST N OF UPPER MI AND THERE WILL BE A DRY AIRMASS TO OVERCOME INITIALLY... OPTED TO MAINTAIN A DRY FCST WED WITH THE EXCEPTION OF NRN LAKE SUPERIOR. NEXT SHORTWAVE TROF SWINGS THRU THE UPPER LAKES ON THU. SINCE ANTECEDENT AIRMASS WON`T BE AS DRY AS WED...ISENTROPIC ASCENT MAY BE SUFFICIENT FOR SOME -SN WITH THIS SYSTEM LATE WED NIGHT THRU THU MORNING. HAVE THUS RETAINED SLIGHT CHC POPS FOR -SN AS SHORTWAVE PASSES. FRI THRU MON...ALTHOUGH THERE ARE SIGNIFICANT MODEL DIFFERENCES WITH THE PATTERN ACROSS THE CONUS...IT APPEARS AT THE MOMENT THAT THIS SHOULD BE A RELATIVELY QUIET PERIOD OF WEATHER ACROSS THE FCST AREA. THE ECMWF DEVELOPS MUCH MORE TROFFING OVER THE WRN CONUS OVER THE WEEKEND INTO EARLY NEXT WEEK THAN THE GFS...RESULTING IN SW FLOW TAKING SHAPE INTO THE GREAT LAKES. THE GFS HAS A W TO NW FLOW INTO THE GREAT LAKES AS POLAR VORTEX OVER HUDSON BAY MAINTAINS INFLUENCE OVER THE AREA. THE GLOBAL CANADIAN OFFERS A SOLUTION BTWN THE GFS AND ECMWF. GIVEN THE DIFFERENCES...IT`S USUALLY BEST TO MAKE MINIMAL CHANGES TO PREVIOUS FCST UNTIL BETTER MODEL AGREEMENT DEVELOPS. IN THIS CASE...THE PREVIOUS FCST LINES UP REASONABLY WELL WITH THE GFS...AND THE 12Z ECMWF HAS TRENDED SOMEWHAT TOWARD THE GFS SOLUTION. SO...WILL MAINTAIN LOW POPS OVER THE WEEKEND FOR THE POSSIBILITY OF A COLD FRONT SETTLING INTO THE UPPER LAKES EARLY SAT AND THEN THE POTENTIAL FOR ANOTHER FROPA SUN. AIRMASS SHOULD BE WARM ENOUGH TO FOR MIXED PTYPES (-SN/-RA) DURING THE AFTN HRS. EXPECT A DRY DAY MON. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... VFR INITIALLY BUT CONDITIONS SHOULD ABRUPTLY DETERIORATE LATE THIS AFTN INTO TONIGHT AS LOW PRESSURE SYSTEM AND HEAVY SNOW OVER THE PLAINS MOVE INTO THE AREA. ONSET OF IFR/LIFR CONDITIONS EXPECTED AT SAW WITH ARRIVAL OF SN LATE THIS AFTN WITH SLIGHTLY LATER ARRIVAL AT CMX. POTENTIAL FOR VERY LOW IFR THIS EVENING AS WINDS/BLSN INCREASE. BETTER POTENTIAL IS AT SAW WITH MORE FAVORABLE NORTH WIND DIRECTION...ESPECIALLY CLOSER TO 12Z WHEN SNOW IS NOT AS WET. WINDS COULD BE VERY STRONG AT SAW TONIGHT WITH GUSTS OF 40 KNOTS POSSIBLE. CONDITIONS AT BOTH TAF SITES SHOULD IMPROVE DRAMATICALLY TOMORROW... STARTING IN THE MORNING AT CMX AND EARLY AFTERNOON AT SAW AS DRIER AIR WORKS IN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRESSURE OVER IOWA WILL DEEPEN TONIGHT AS IT LIFTS TO NORTHERN LAKE HURON BY TUE MORNING. 35 KT GALE FORCE WINDS ARE EXPECTED TO DEVELOP ACROSS LAKE SUPERIOR THIS EVENING...THEN INTENSIFY TO 40 TO 45 KT AFTER MIDNIGHT. IT IS POSSIBLE FOR STORM FORCE WINDS TO OCCUR ON EASTERN LAKE SUPERIOR TOMORROW MORNING...BUT CONFIDENCE IS NOT HIGH ENOUGH YET TO ISSUE THE STORM WARNING. WINDS WILL COME DOWN FAIRLY QUICK TOMORROW AS THE LOW DEPARTS AND A HIGH PRESSURE RIDGE BUILDS IN. BEYOND TUE NIGHT...WINDS LOOK TO REMAIN BELOW 25 KT THROUGH THE REST OF THE FORECAST. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... BLIZZARD WARNING UNTIL 2 PM EDT TUESDAY FOR MIZ005. BLIZZARD WARNING UNTIL 5 PM EDT TUESDAY FOR MIZ006. WINTER STORM WARNING UNTIL 1 PM EDT /12 PM CDT/ TUESDAY FOR MIZ002-009-013-014-084. WINTER STORM WARNING UNTIL 5 PM EDT TUESDAY FOR MIZ007-085. WINTER STORM WARNING UNTIL 2 PM EDT TUESDAY FOR MIZ004. WINTER STORM WARNING UNTIL 7 AM CDT TUESDAY FOR MIZ010>012. SNOW AND BLOWING SNOW ADVISORY UNTIL 1 PM EDT TUESDAY FOR MIZ001-003. LAKE SUPERIOR... GALE WARNING FROM 10 PM THIS EVENING TO 8 PM EDT TUESDAY FOR LSZ267. GALE WARNING UNTIL 8 PM EDT TUESDAY FOR LSZ265-266. GALE WARNING UNTIL 2 PM EDT TUESDAY FOR LSZ264. GALE WARNING FROM 1 AM TO 2 PM EDT TUESDAY FOR LSZ248-249. GALE WARNING FROM 11 PM THIS EVENING TO 2 PM EDT TUESDAY FOR LSZ244>247. GALE WARNING UNTIL 11 AM EDT /10 AM CDT/ TUESDAY FOR LSZ240>243. GALE WARNING UNTIL 2 AM EDT TUESDAY FOR LSZ162. GALE WARNING UNTIL 8 AM EDT TUESDAY FOR LSZ263. GALE WARNING FROM 1 AM TO 6 PM EDT TUESDAY FOR LSZ250-251. LAKE MICHIGAN... GALE WARNING FROM 8 AM TO 3 PM EDT TUESDAY FOR LMZ221-248-250. && $$ SYNOPSIS/SHORT TERM...AJ LONG TERM...ROLFSON AVIATION...AJ MARINE...AJ
AREA FORECAST DISCUSSION
NWS GAYLORD MI
436 PM EDT MON MAR 31 2008 .SYNOPSIS...A STRONG STORM SYSTEM WILL MOVE INTO CENTRAL LOWER MICHIGAN TONIGHT. WIDESPREAD PRECIPITATION WILL OVERSPREAD THE REGION RESULTING IN POTENTIAL HEAVY RAIN AND SNOW. THIS STORM SYSTEM WILL EXIT THE REGION TUESDAY WHILE COLD AIR AND STRONG WINDS PLOW INTO ALL OF MICHIGAN. HIGH PRESSURE WILL THEN SETTLE IN WEDNESDAY WITH SEASONABLE TEMPERATURES THROUGH THE REMAINDER OF THE WEEK. && .DISCUSSION...SFC/RUC/SATELLITE/RADAR AND UPPER AIR ANALYSIS SHOWING SHORTWAVE TROUGH LIFTING OUT OF THE ROCKIES WHILE SFC LOW PRESSURE IS DEEPENING OVER NRN MO/SRN IOWA AS IT CONTINUES TO LIFT NORTHEAST. STORMS HAVE FIRED ALONG THE COLD FRONT WHICH WAS DRAPED FROM THE LOW...TO MO/AR/OK. THIS IS SEEMINGLY ROBBING US OF SOME OF THE DEEPEST MOISTURE TO THE SOUTH. TEMPERATURES HAVE BEEN VERY SLOW TO CLIMB...AS WARM FRONT REMAINS TO THE SOUTH OF US...AND AN EASTERLY FLOW OFF THE LAKE HAS KEPT READINGS IN THE 30S. INITIAL SHORTWAVE WORKING INTO THE WESTERN GREAT LAKES AND WAS RESULTING IN EXPANDING RAIN SHIELD SPREADING INTO NRN MICHIGAN. TONIGHT...SFC OW WILL WORK INTO CENTRAL LOWER TONIGHT AND STRONGEST H7-H5 -DIVQ SPREADS IN ACROSS UPPER MICHIGAN WITH A SECOND AREA ACROSS SRN LOWER THIS EVENING. THIS FORCING COMBINED WITH H3-H2 UPPER DIVERGENCE ASSOCIATED WITH STRONG UPPER JET OF 120KTS AND STRONG AND DEEP FGEN RESPONSE SUGGESTIVE OF ENHANCED BANDED PRECIPITATION. MODEL CROSS SECTIONS SHOW THE STRONG SLOPED FRONTAL SURFACE WITH -EPV AND BULLSEYE OF LIFT CENTERED OVER PLN. AREA TAMDAR SOUNDINGS ARE SUPPORTING NAM/GFS SOUNDINGS OF MAINLY A SNOW EVENT ACROSS CHIPPEWA COUNTY...MIXED SNOW AND SLEET ACROSS MAINLY MACKINAC COUNTY...AND ALL RAIN FOR PRETTY MUCH ALL OF NRN LOWER MICHIGAN. THERE IS A +1.5C SWATCH OF AIR THROUGH 3KFT ACROSS CIU...BUT WITH A BIT OF DRY AIR BELOW THIS (CIGS 6KFT)...EVAP COOLING SHOULD ALLOW ANY ONSET OF RAIN...TO SWITCH OVER TO SNOW RATHER QUICKLY. THIS ESPECIALLY TRUE IN THE PRESENCE OF SUCH STRONG VERTICAL MOTIONS THAT ARE EXPECTED. OVERALL...STILL SEE POTENTIALLY 10 INCHES OF SNOW NEAR PARADISE TAPERING OFF RATHER QUICKLY TO MAYBE A COUPLE OF INCHES NEARER TO DRUMMOND ISLAND. CONVECTIVE ACTIVITY COULD ALLOW FOR SNOW TO MIX IN WITH RAIN ACROSS PORTIONS OF FAR NRN LOWER...BUT AGAIN...MAINLY RAIN EXPECTED. FINALLY...LOOK FOR STRONG WINDS TO DEVELOP LATE TONIGHT ACROSS WHITEFISH BAY AS LOW PASSES EAST AND COLD AIR STARTS TO WORK INTO FAR WESTERN CHIP/MACK. COULD SEE GUSTS TO 35 MPH DEVELOP LATE...AND QUITE POSSIBLY ACROSS WHITEFISH BAY THIS EVENING TOO. THE STRONG WINDS WILL DEVELOP OVER ALL OF NRN MICHIGAN TUESDAY. TEMPERATURES WILL ACTUALLY RISE OVERNIGHT IN AREAS SOUTH OF M-32 AS WARM FRONT LIFTS NORTH OF THIS AREA. THERE IS A CHANCE THAT GUSTY WINDS COULD DEVELOP NEAR THE BAY...BUT GOING INTO NIGHT TIME...DO NOT SEE WHERE DEEP ENOUGH MIXING COULD MAKE THIS A FACTOR. WILL HAVE READINGS RISING INTO THE MIDDLE 40S FOR THESE AREAS...WHILE TEMPERATURES REMAIN NEARLY STEADY IN THE 30S OR SLOWLY FALL (EASTERN UPPER). SMD TUESDAY...THE STORM SYSTEM WILL BE LOCATED BETWEEN SAGINAW BAY AND ALPENA ALONG THE LAKE HURON SHORELINE AT 12Z...EXITING QUICKLY TO THE NORTHEAST OF LAKE HURON DURING THE AFTERNOON. ADDITIONAL LIFT TUESDAY...WILL BE FROM A 500MB TROUGH SWEEPING OVER THE GREAT LAKES REGION DURING THE DAY. THIS TROUGH IS ALSO EXPECTED TO MOVE EAST OF LAKE HURON BY THE AFTERNOON. 850-700MB FRONTOGENESIS SHOWS THE BEST LIFT WITH THE EXITING SFC LOW...TO REMAIN OVER THE STRAITS AND EAST UPPER MICHIGAN...MAINLY INTO THE AFTERNOON BEFORE DIMINISHING BY EVENING. MODEL SOUNDINGS FROM THE STRAITS NORTH...SHOW ABUNDANT MSTR FROM THE SFC THROUGH 500MB...WITH AN ENTIRE SOUNDING BELOW FREEZING. QPF FORECAST WOULD SUGGEST ANOTHER 3 TO 5 INCHES POSSIBLE IN THE REGION INTO THE AFTERNOON...THEREFORE WILL LEAVE WINTER STORM WARNING IN EFFECT FOR EAST UPPER. FOR NORTHERN LOWER MICHIGAN LOCATIONS WEST OF I-75...SOUNDINGS SHOW SOME MIX POSSIBLE FIRST THING IN THE MORNING QUICKLY BECOMING SNOW...THEN POSSIBLE DRIZZLE IN THE AFTERNOON AS MID AND UPPER LVL MSTR STRIPS OUT. FOR THE REST OF NRN LOWER MICHIGAN...850MB WET BULBS WILL BE ABOVE ZERO IN THE MORNING DROPPING BELOW ZERO IN THE AFTERNOON. THEREFORE WILL CONTINUE A CHANCE OF RAIN/DRIZZLE IN THE MORNING...BEFORE BECOMING LIGHT SNOW IN THE AFTERNOON. WILL HAVE GALE WARNINGS OVER NRN MICHIGAN NEARSHORES IN EFFECT THROUGH TUESDAY AFTERNOON...AS WIND GUSTS BEHIND THE EXITING FRONT INCREASE TO BTW 35 AND 40KTS. WILL CONTINUE GALE WARNINGS INTO THE EARLY EVENING BEFORE WINDS DIMINISH WITH INCREASE HIGH PRESSURE. THE STRONG WINDS WILL ALSO RESULT IN BLOWING AND DRIFTING SNOW ACROSS EASTERN UPPER THAT COULD POTENTIALLY RESULT IN SIGNIFICANTLY REDUCED VISIBILITIES. TUESDAY NIGHT...A STRONG AREA OF HIGH PRESSURE WILL BUILD BACK INTO THE WRN LAKES FROM THE UPPER MIDWEST EARLY TUESDAY EVENING... ACCOMPANIED BY 500MB ZONAL FLOW ALOFT. MODEL SOUNDINGS AND MSTR PROGS SHOWING DRYING CONDS MOVING OVER THE GREAT LAKES REGION QUICKLY DURING THE EVENING...DROPPING TO AROUND 30 PCT BETWEEN 850-500 AROUND 00Z WED. OVERALL WILL MAINTAIN THE DRY CONDITIONS OVER THE FORECAST. HOWEVER WILL MENTION SOME EARLY EVENING LAKE INDUCED SNOW SHOWERS OVER PORTIONS OF NORTHWEST LOWER AND EAST UPPER MICHIGAN. 850 MB TEMPS ARE PROGGED AROUND -12C...WITH NRN LAKE MI WATER TEMPS NEAR +1C. 925-850 MB WINDS WILL BE FROM THE NORTHWEST WITH 900-700 MB RH ARND 80 PCT...QUICKLY DRYING TO UNDER 30 PCT BY 06Z. MODEL SOUNDINGS SHOW AN INVERSION HEIGHT AROUND 5K FT AROUND 00Z...QUICKLY DIMINISHING TO UNDER 3500FT BY 06Z. SNOWFALL AMOUNTS WILL BE UNDER ONE INCH...AS LW LVL MSTR DOES NOT EXTEND UP MUCH PASS -11C DURING THIS PERIOD AND MODELS SHOW DRY AIR QUICKLY MOVING BACK IN. WEDNESDAY/WEDNESDAY NIGHT...A LARGE AREA OF HIGH PRESSURE IS PROGGED TO MOVE OVER THE UPPER MIDWEST WEDNESDAY MORNING...BECOMING CENTERED OVER THE REGION IN THE AFTERNOON. THE HIGH IS FORECAST TO MOVE EAST ONTO THE MID ATLANTIC COAST BY 12Z THURSDAY...HOWEVER SFC RIDGING IS FORECAST TO LINGER OVER THE GREAT LAKES REGION INTO THURSDAY. AT UPPER LEVELS 500 MB...APPEARS TO BE ZONAL THRU THE PERIOD WITH A WEAK UPPER TROUGH SLIDING INTO THE WRN LAKES REGION THURSDAY MORNING. OVERALL WILL CONTINUE WITH DRY CONDS WED AND WED NIGHT. HIGH TEMPERATURES...WITH AT LEAST PARTIAL SUNSHINE AND 850 MB TEMPS RUNNING AROUND -4C...WOULD SUGGEST HIGH TEMPERATURES FROM AROUND 40 OVER EAST UPPER MICHIGAN TO THE MID 40S OVER THE SOUTHERN PORTIONS OF THE FORECAST AREA. WILL MENTION OVERNIGHT LOWS FALLING BACK TO NEARLY NORMAL IN THE MID 20S...AS SKIES SHOULD REMAIN FAIRLY CLEAR OVERNIGHT. THURSDAY...HIGH PRESSURE RIDGING STILL THE DOMINATE FEATURE OVER THE GREAT LAKES THRU MUCH OF THE PERIOD...WHILE THE UPPER LEVELS REMAIN FAIRLY ZONAL THRU THE AFTN. OVERALL WILL MENTION PARTLY SUNNY SKIES AND DRY CONDITIONS THROUGH THE DAY. AFTERNOON HIGHS SHOULD ONCE AGAIN BE IN THE MID 40S WITH 850 MB TEMPS AROUND -3C AND SOME SUN...AND POSSIBLY LESS SNOW COVER. WILL KEEP THE MENTION OF A CHANCE OF PCPN OVER THE SOUTHEAST CWA THURSDAY NIGHT AS A SHORT WAVE TROUGH MOVES OVER THE UPPER MIDWEST AND WRN LAKES REGION. THIS WILL COMBINE WITH A STORM SYSTEM PROGGED TO MOVE ONCE AGAIN INTO THE OHIO VALLEY. WILL MENTION THIS PCPN AS MAINLY SNOW AS OVERNIGHT LOWS FALL INTO THE MID 20S...ALONG WITH BEING WELL NORTH OF THE OHIO VALLEY STORM SYSTEM. FRIDAY THRU MONDAY...UPPER LEVEL PATTERN SHOWING NEARLY ZONAL FLOW ACRS THE UPPER LAKES FRIDAY THROUGH SATURDAY. PATTERN AT THE SFC A LITTLE LESS ORGANIZED AND NON-DISTINCT...WITH WEAK HIGH PRESSURE OVER THE REGION THRU SATURDAY WHILE A STORM SYSTEM REMAINS OVER HUDSON BAY. 850MB TEMP PATTERN REMAINS THE SAME...GENERALLY HANGING AROUND -3C TO -4C WHICH SHOULD GENERATE TEMPS IN THE MID 40S ACROSS MUCH OF NRN LOWER WITH LOWER 40S OVER EAST UPPER. THE SRN PORTIONS OF THE FORECAST AREA SHOULD BEGIN WARMING QUITE EFFICIENTLY THIS WEEKEND AS SNOW LINE CONTINUES TO SLOWLY MOVE NORTH. WILL MENTION A CHANCE OF PCPN SUNDAY...AS UPPER TROUGH STRENGTHENS OVER THE UPPER LAKES...FROM A LOW CENTERED OVER HUDSON BAY. THE SFC RESPONSE IS A WEAK BOUNDARY PROGGED TO MOVE OVER THE STATE SUNDAY...WITH HIGH PRESSURE PROGGED TO MOVE BACK OVER THE STATE SUNDAY NIGHT AND MONDAY. WILL KEEP THE FORECAST AREA DRY MONDAY WITH THE RIDGE OF HIGH PRESSURE MOVING OVER THE WRN LAKES...WILL MENTION WARMER HIGHS FOR THE SRN CWA DUE TO LACK OF SNOW BY THAT TIME AND POTENTIAL FOR SUN. SWR && .AVIATION... && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WARNING UNTIL 5 PM EDT TUESDAY FOR MIZ008-015. LM...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LMZ323-341-342- 344>346. LH...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LHZ345>349. LS...GALE WARNING FROM 5 AM TO 11 PM EDT TUESDAY FOR LSZ322. GALE WARNING UNTIL 11 PM EDT TUESDAY FOR LSZ321. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
142 PM EDT MON MAR 31 2008 UPDATED UPDATE...AVIATION AND WWA SECTIONS FOR BLIZZARD WARNING AND 18Z TAF ISSUANCE. .UPDATE... AFTER LOOKING AT THE 12Z CYCLE...WENT AHEAD AND UPGRADED MARQUETTE AND ALGER COUNTIES TO BLIZZARD WARNINGS...WHERE A PERIOD OF STRONG NORTH WINDS (GUSTS TO 35-40KT) WILL COMBINE WITH LAKE ENHANCEMENT AND UPSLOPE. AGAIN...THIS PERIOD LOOKS THE BEST BETWEEN 10-15Z TUE. UPDATE AS OF 1041 AM EDT... GOING FORECAST APPEARS TO BE IN GOOD SHAPE. REGIONAL RADAR LOOP... SFC OBS AND IR SATELLITE IMAGERY DEPICTS A LARGE AREA OF PCPN COVERING ERN SD...SRN MN...NRN IA AND NOW ENTERING FAR WRN WI. WITHIN THE PCPN...THE RAIN/SNOW LINE CURRENTLY APPEARS TO BE LOCATED FROM SIOUX CITY IA TO NEAR OWATTANA MN. IN THE SNOW AREA...SOME LOCATIONS HAVE BEEN EXPERIENCING RATES OF ONE INCH PER HOUR (EXAMPLE SIOUX FALLS SD). PCPN IS BEING DRIVEN BY A FEW DIFFERENT MECHANISMS. THE FIRST IS A GENERAL 100KT UPPER LEVEL JET STREAK WHICH EXTENDS FROM CENTRAL MN INTO NE ONTARIO...PLACING SRN MN AND NRN IA IN THE RIGHT ENTRANCE REGION. THE SECOND IS A SHRTWV OVER SOUTH CENTRAL NEBRASKA...WHICH IS PRODUCING DPVA DOWNSTREAM OVER ERN NEBRASKA INTO NRN IA. THE THIRD FEATURE IS STRONG 700-600MB FRONTOGENESIS PER RUC ANALYSIS AND 12Z RAOBS... CURRENTLY SITUATED IN NW IA. LIKE YESTERDAY...MODELS ARE STILL IN DISAGREEMENT ON THE TRACK OF THIS HEAVY PCPN. SIMPLE LINEAR EXTRAPOLATION WOULD BRING IT ACROSS THE SOUTH CENTRAL U.P....WHICH IS IN GOOD AGREEMENT WITH THE 06Z/12Z NAM...LOCAL WRF-ARW RUN AND THE 06Z GFS. THE 12Z RUC IS A BIT NORTHWEST...CROSSING IRON AND ERN GOGEBIC...BUT IT MAYBE ONTO SOMETHING AS PCPN IS INTENSIFYING FROM THE MPX AREA UP TOWARDS DLH. THEREFORE ADJUSTED THE FORECAST FOR SLIGHTLY HIGHER QPF AMOUNTS BOTH IN THE FAR WEST AND SOUTH CENTRAL BETWEEN 18-00Z TODAY. CONCERN STILL REMAINS REGARDING P-TYPE ACROSS MENOMINEE COUNTY AS SOUNDINGS FROM THE VARIOUS MODELS AT MNM COULD RESULT IN RAIN...SLEET OR POSSIBLY SNOW...WHILE TRANSITIONING TO ALL SNOW AS YOU MOVE FARTHER NORTH TOWARDS US-2. ONE ITEM OF NOTE IS THAT AS THE PCPN MOVES NORTHEAST...MODELS DEPICT BOTH THE UPPER LEVEL JET AND 700-600MB FRONTOGENESIS INCREASING. IF THIS IS TRUE...WHICH SEEMS VERY PLAUSIBLE...PCPN MAY COME DOWN AT VERY HEAVY RATES. SNOWFALL AMOUNTS OF 1-2 INCHES PER HOUR OF THE WET VARIETY (SNOWFALL RATIOS OF 5-10 TO 1) SEEMS LIKELY. THIS WILL BE STRESSED IN THE 11 AM WSW UPDATE. NEXT ITEM OF CONCERN WHICH IS LATER ON IN THE FORECAST IS POTENTIAL FOR BLIZZARD CONDITIONS IN THE NORTH CENTRAL U.P.. NEW 12Z NAM IS ABOUT 3 MB DEEPER THAN THE 06Z RUN WITH THE LOW OVER NRN LAKE HURON AT 12Z TUE...NOW FORECAST AT 992MB. THE 06Z RUN ALREADY INDICATED A POTENTIAL FOR 40 KT GUSTS AT 12Z TUE OVER THE NORTH CENTRAL U.P. USING THE MOMENTUM TRANSFER METHOD...AND THIS 12Z RUN NOW INDICATES 55 KT AT 900MB IN THE MIXED LAYER...SUGGESTING 40-45 KT GUSTS. WILL WAIT FOR THE 12Z GFS AND REGIONAL CANADIAN BEFORE DECIDING TO UPGRADE MARQUETTE...ALGER AND POSSIBLY BARAGA TO BLIZZARD WARNINGS. 06Z GFS WAS ALSO FAIRLY STRONG WITH THE WINDS. LOOKS LIKE RIGHT NOW THE BEST PERIOD OF POTENTIAL BLIZZARD CONDITIONS IS BETWEEN 10-15Z TUE. && .SYNOPSIS (412 AM EDT)... RECENT WV IMAGERY AND UA PLOTS SHOWING TROUGH OVER THE WRN US...A RIDGE OVER THE ERN US...AND AN NORTHERLY MOVING UPPER LOW OVER SOUTHERN HUDSON BAY. WV IMAGERY SHOWING SHORTWAVE MOVING OUT OF THE CNTRL ROCKIES...WITH UPPER TROUGH AXIS OVER ERN WA/OR. AT THE SFC...HIGH PRESSURE CURRENTLY OVER THE NE US UNDER THE RIDGE AXIS...WHILE SFC LOW IS DEEPENING OVER CO/NM AS IT INTERACTS WITH THE UPPER WAVE. FARTHER N...1004MB SFC LOW MOVING INTO HUDSON BAY...AS A WEAK TROUGH STRETCHES SOUTH ACROSS ONTARIO AND INTO UPPER MI. THIS TROUGH IS PRODUCING A FEW RADAR ECHOS ACROSS THE WRN AND ERN HALVES OF UPPER MI. HAVEN`T SEEN TOO MANY SFC OBS INDICATING PCPN THUS FAR...AS 01Z MQT AND RHI TAMDAR SOUNDINGS SHOW VERY DRY AIR BELOW H700. && .DISCUSSION (412 AM EDT)... MAIN CONCERN FOR THE FORCAST IS THE APPROACHING SYSTEM FOR THIS AFTERNOON THROUGH TUESDAY MORN. OVERALL...NAM/GFS/ECMWF ALL LOOK TO BE IN FAIRLY GOOD AGREEMENT WITH THE SYSTEM. SFC LOW OVER THE CO/NM WILL CONTINUE TO BE ENHANCED BY SHORTWAVE CURRENTLY MOVING THROUGH THE CNTRL ROCKIES AND THE LEFT FRONT REGION OF AN UPPER JET STREAK OVER THE SW US. AS THE JET STREAK AND SHORTWAVE SLIDE NE...THE SFC LOW IS EXPECTED TO CONTINUE TO MOVE OUT OF KS/OK AT 12Z AND TO THE NE INTO ERN IA BY 00Z TUESDAY AND THEN E.C. LOWER MI BY 12Z TUESDAY. MODELS SHOW THE LOW INTENSIFYING BETWEEN 00-12Z TUESDAY...AS LOW MOVES UNDER RIGHT REAR OF NORTHERN JET...WHICH WILL PROVIDE ADDITIONAL UPPER DIVERGENCE. INITIAL SHORTWAVE MOVES NE ACROSS THE CWA MON AFTN...WITH PCPN STARTING DURING THE LATE MORNING NEAR THE WI BORDER AND THEN SPREADING NE DURING THE AFTN. SECOND WAVE AND UPPER TROUGH WILL THEN MOVE THROUGH DURING THE OVERNIGHT HOURS MON AND INTO TUES MORN. STRONG SW WINDS BETWEEN H925-850 WILL BRING PLENTY OF MOISTURE NORTH FROM THE OPEN GULF...WITH H1000-700 MIXING RATIOS EXCEEDING 3 AND PW/S OVER A HALF INCH...WHICH IS NEARLY 200 PERCENT OF NORMAL...ACROSS THE ERN HALF OF THE CWA. THIS WILL PROVIDE PLENTY OF MOISTURE TO WORK WITH AS THE SYSTEM MOVES THROUGH. FORCING APPEARS PLENTIFUL AS SYSTEM TRACKS THROUGH THE AREA...WITH THE STRONGEST FORCING ACROSS THE E/SE HALF OF THE CWA. STRONG WAA AND ISENTROPIC ASCENT SHOWN ON ALL OF THE MODELS IN THE LOWER LEVELS...WITH DECENT DIVQ BETWEEN H500-300...BETWEEN 00-09/12Z TUES. GFS/NAM INDICATING SOME DRIER AIR NOSING NE ACROSS THE EASTERN HALF OF THE CWA BETWEEN H700-500 DURING THE LATE OVERNIGHT AND EARLY MORNING...WHICH WILL DIMINISH THE STRONGER PCPN IN THE SOUTH CENTRAL UP AS DEEP MOISTURE DIMINISHES AND SNOW GROWTH AREA DRIES OUT. APPEARS TO BE TWO AREAS OF FRONTOGENTIC FORCING...ONE ALONG AREA OF STRONGEST FORCING OVER THE ERN HALF OF THE CWA AND A SECOND FARTHER NW ALONG THE FAR WRN PART OF THE UP. THIS SECOND AREA OF FRONTOGENTIC FORCING WILL ENHANCE THE PCPN AMOUNTS AWAY FROM THE SYNOPTIC FORCING OF THE SYSTEM OVER GOGEBIC AND ONTONAGON COUNTIES. DO HAVE SOME CONCERN ON THE PCPN AMOUNTS IN THE IRON COUNTY AREA...AS THE AREA LOOKS TO BE BETWEEN THE STRONGEST FORCING FROM THE SYSTEM AND LAKE ENHANCEMENT...BUT AT THIS TIME WILL LEAVE THE FORECAST AS IS. H700 LOW LOOKS TO TRACK RIGHT ACROSS UPPER MI...WITH STRONG THERMAL GRADIENT FROM SW TO NE ACROSS CENTRAL UPPER MI...WHILE H850 LOW AND THERMAL GRADIENT SLIDE NE ACROSS KMNM AND NORTHERN LK MI. H850 TEMPS REACH 10C ALONG NW LOWER MI BY 00Z TUESDAY WHILE THE -6C ISOTHERM STRETCHES FROM KMQT TO KEGV. THE LOCATION OF THE 0C ISOTHERMS ALOFT DOES BRING SOME CONCERN WITH THE PCPN TYPE IN THE KMNM AREA AND RIGHT ALONG THE LAKE MI SHORELINE MONDAY EVENING AND EARLY OVERNIGHT...BEFORE COLDER AIR WRAPS AROUND THE EXITING LOW AND TRANSITIONS PCPN TO ALL SNOW. BUFKIT SOUNDINGS SHOW A MIXED BAG OF PCPN IN THE MNM AREA...AS PCPN LOOKS TO BE MAINLY SNOW INITIALLY...THEN TRANSITIONING TO A SLEET/RAIN SOUNDING DURING THE LATE AFTN AND EVENING AS WARM AIR BETWEEN H700-800 SHOULD BE ENOUGH TO MELT ANY SNOW. DRY AIR ABOVE H700 ALSO MOVES IN AT THIS TIME...SO EXPECT THE ICE CRYSTALS TO BE VERY LIMITED...IF EVEN PRESENT. AS COLD AIR WRAPS BACK IN DURING THE OVERNIGHT HOURS...EXPECT PCPN TO CHANGE BACK TO SNOW. HAVE ADJUSTED SNOW AMOUNTS IN THIS AREA...DUE TO A QUICK COUPLE INCHES OF SNOW INITIALLY BEFORE CHANGING OVER TO A SLEET/RAIN IN THE EVENING. WINDS LOOK TO GET PRETTY GUSTY BETWEEN 06-18Z TUES...AS LOW PUSHES TO THE NORTHEAST AND INTO CANADA. H925-850 WINDS LOOK TO BE IN THE 35-45KT RANGE...WHICH SHOULD BRING SOME GUSTS TO 35 TO 40KTS ALONG LK SUPERIOR IN MARQUETTE...ALGER...AND LUCE COUNTIES. THESE STRONG WINDS GUSTS WILL BRING BLOWING AND DRIFTING SNOW...EVEN WITH THE SNOW INITIALLY BEING HEAVY AND WET. WITH THE STRONGEST WINDS COMING DURING THE TIME PERIOD WHERE THERE IS THE BEST SNOW GROWTH AND STRONG LK ENHANCEMENT...BELIEVE THERE WILL BE SOME LOCATIONS RECEIVING WHITEOUT CONDITIONS...ESPECIALLY ALONG THE LK SHORE OF THE PREVIOUSLY MENTIONED COUNTIES. DON`T HAVE ENOUGH CONFIDENCE ON STRENGTH OF WINDS AND REDUCED VISBYS AT THIS TIME...BUT WILL PASS ALONG TO DAY SHIFT OF POSSIBILITY OF BLIZZARD CONDITIONS. THE FINAL FEATURES TO HAVE AN EFFECT ON THE AREA WILL BE THE LK ENHANCEMENT AND UPSLOPE FLOW ALONG LK SUPERIOR. BELIEVE THIS WILL HAVE A PRETTY STRONG INFLUENCE ON PCPN AMOUNTS IN THE HIGHER TERRAIN AREAS IN MARQUETTE AND BARAGA COUNTIES AS STRONG NNE WINDS BLOW ACROSS THE LK. THIS ENHANCEMENT CAN BE SEEN ON THE LOCAL HIRES WRF...NAM12...AND EVEN GFS40. THEREFORE...HAVE CONTINUED TO INCLUDE THE ENHANCED PCPN IN THOSE AREAS. OTHERWISE...EXPECT SNOW RATIOS TO INCREASE AWAY FROM THE 10-12 TO 1 VALUES ACROSS MOST OF THE AREA DURING THE OVERNIGHT TO MORE LES 20-1 RATIOS ALONG THE LK SUPERIOR SHORELINE ON TUESDAY MORNING. DELTA T VALUES LOOK TO BE MARGINAL...WITH VALUES AROUND 11C...BUT STRONG OMEGA WITHIN THE DGZ AND DEEP MOISTURE ON TUES MORNING...SHOULD BE ENOUGH TO ENHANCE THE SNOW RATIOS. ALL IN ALL...BELIEVE THAT THE GOING FORECAST FOR THE STORM IS ON TRACK...WITH THE BIGGEST CONCERNS BEING THE RAIN/SLEET/SNOW ALONG LK MI AND CORRESPONDING QPF/SNOW AMOUNTS. SYSTEM EXITS FAIRLY QUICKLY ON TUESDAY AND INTO WED...AS WEAK UPPER RIDGING MOVES OVER THE AREA AND STRONG SFC HIGH BUILDS EAST. THIS WILL KEEP THE WEATHER QUIET FOR THE UP THROUGH WED NIGHT...AS THE REGION REMAINS UNDER THE HIGH AND WEAK UPPER RIDGE. 12Z ECMWF AND 00Z GFS HINTING AT SHORTWAVE MOVING THROUGH ON WED NIGHT AND INTO THURS. LOOKS TO HAVE LIMITED MOISTURE TO WORK WITH FROM EXITING HIGH...SO HAVE JUST MADE A SLIGHT ADJUSTMENT TO THE TIMING FOR WED NIGHT AND THURS...BUT FUTURE SHIFTS WILL NEED TO FINE TUNE THE TIMING AND POPS. DIDN`T MAKE ANY CHANGES TO THE FORECAST PAST THURS. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... VFR INITIALLY BUT CONDITIONS SHOULD ABRUPTLY DETERIORATE LATE THIS AFTN INTO TONIGHT AS LOW PRESSURE SYSTEM AND HEAVY SNOW OVER THE PLAINS MOVE INTO THE AREA. ONSET OF IFR/LIFR CONDITIONS EXPECTED AT SAW WITH ARRIVAL OF SN LATE THIS AFTN WITH SLIGHTLY LATER ARRIVAL AT CMX. POTENTIAL FOR VERY LOW IFR THIS EVENING AS WINDS/BLSN INCREASE. BETTER POTENTIAL IS AT SAW WITH MORE FAVORABLE NORTH WIND DIRECTION...ESPECIALLY CLOSER TO 12Z WHEN SNOW IS NOT AS WET. WINDS COULD BE VERY STRONG AT SAW TONIGHT WITH GUSTS OF 40 KNOTS POSSIBLE. CONDITIONS AT BOTH TAF SITES SHOULD IMPROVE DRAMATICALLY TOMORROW... STARTING IN THE MORNING AT CMX AND EARLY AFTERNOON AT SAW AS DRIER AIR WORKS IN. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FEATURE OF INTEREST IS A LOW PRESSURE SYSTEM DEVELOPING OVER OKLAHOMA. THIS LOW WILL DEEPEN AS IT MOVES TO NORTHERN LAKE HURON TUESDAY MORNING. AS THE LOW APPROACHES...EXPECT NORTHEAST GALES ON LAKE SUPERIOR BY THIS EVENING...THEN SHIFT NORTHERLY TUESDAY MORNING. STILL A POTENTIAL FOR A BRIEF PERIOD OF STORM FORCE WINDS OVER SOUTH CENTRAL LAKE SUPERIOR LATE TONIGHT INTO MID MORNING TUESDAY. FOR NOW...KEPT WINDS TOPPED OFF AT 45 KNOTS. WINDS DIMINISH QUICKLY BY TUESDAY EVENING AS A RIDGE OF HIGH PRESSURE BUILDS IN. BEYOND TUESDAY...EXPECT WINDS TO REMAIN AT OR BELOW 30 KNOTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... BLIZZARD WARNING UNTIL 2 PM EDT TUESDAY FOR MIZ005. BLIZZARD WARNING UNTIL 5 PM EDT TUESDAY FOR MIZ006. WINTER STORM WARNING UNTIL 1 PM EDT /12 PM CDT/ TUESDAY FOR MIZ002-009-084. WINTER STORM WARNING UNTIL 5 PM EDT TUESDAY FOR MIZ007-085. WINTER STORM WARNING UNTIL 2 PM EDT TUESDAY FOR MIZ004. WINTER STORM WARNING UNTIL 1 PM EDT TUESDAY FOR MIZ013-014. WINTER STORM WARNING UNTIL 7 AM CDT TUESDAY FOR MIZ010>012. SNOW AND BLOWING SNOW ADVISORY UNTIL 1 PM EDT TUESDAY FOR MIZ001-003. LAKE SUPERIOR... GALE WARNING FROM 8 PM THIS EVENING TO 8 PM EDT TUESDAY FOR LSZ265>267. GALE WARNING FROM 8 PM THIS EVENING TO 2 PM EDT TUESDAY FOR LSZ264. GALE WARNING FROM 2 AM TO 2 PM EDT TUESDAY FOR LSZ244-245-248- 249. GALE WARNING UNTIL 8 AM EDT TUESDAY FOR LSZ263. GALE WARNING UNTIL 2 AM EDT TUESDAY FOR LSZ162. GALE WARNING FROM 2 AM TO 6 PM EDT TUESDAY FOR LSZ250-251. LAKE MICHIGAN... GALE WARNING FROM 8 AM TO 6 PM EDT TUESDAY FOR LMZ248-250. && $$ UPDATE...AJ SYNOPSIS...SRF DISCUSSION...SRF AVIATION...AJ MARINE...JLA
AREA FORECAST DISCUSSION
NWS RALEIGH NC
330 PM EDT MON MAR 31 2008 .SYNOPSIS...COOL HIGH PRESSURE WILL CONTINUE SHIFTING EAST OVER THE WESTERN ATLANTIC TONIGHT... AS A WARM FRONT SURGES WESTWARD THROUGH THE AREA OVERNIGHT... ALLOWING MUCH WARMER AIR TO PUSH INLAND FROM THE COAST. THIS WARMER AIR WILL ENGULF THE ENTIRE AREA TUESDAY AS A MILD SOUTHWEST FLOW TAKES OVER. A COLD FRONT WILL APPROACH FROM THE WEST LATE TUESDAY AND CROSS THE AREA TUESDAY NIGHT. ANOTHER COOL HIGH PRESSURE AREA WILL BUILD IN FROM THE NORTH ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 255 PM MONDAY... THE FORMER COASTAL FRONT... DEMARKING THE LEADING EDGE OF THE SLOWLY ERODING WEDGE AIR MASS... HAS SURGED WELL INLAND THROUGH THE COASTAL PLAIN... AND TEMPERATURES ON ITS EAST SIDE HAVE RISEN WELL INTO THE 60S. READINGS WITHIN THE COLD DOME HAVE CLIMBED VERY MODESTLY... A DEGREE AN HOUR OR SO... AND STILL SIT IN THE MID 40S TO LOWER 50S. HOWEVER THE SURFACE FLOW WITHIN THE HEART OF THE COLD DOME OVER NC HAS TAKEN ON A MORE NORTHERLY COMPONENT... AN EARLY INDICATOR THAT THE DOME IS BEGINNING TO DRAIN... AND THIS IS VERIFIED BY A STEADY WARMING IN THE SURFACE-925 MB LAYER NOTED ON AREA AMDAR AIRCRAFT SOUNDING DATA. THE DAMMING PARENT HIGH... NOW CENTERED WELL TO OUR NE OVER THE WESTERN ATLANTIC... HAS LOST ITS MID LEVEL SUPPORT. WITH THE STEADY FEED OF DRY AIR INTO THE WEDGE NOW CUT OFF... EVAPORATIVE COOLING PROCESSES IN THE COLD DOME HAVE CEASED... HENCE THE SLOW BUT STEADY RISE IN TEMPS IN THE LAST FEW HOURS. WHILE THE STRONG WARM ADVECTION ATOP THE COLD DOME WILL HELP KEEP THE STABLE SURFACE BASED LAYER SUFFICIENTLY STRONG TO SLOW THE WESTWARD INSURGENCE OF THE COASTAL FRONT... THE STRENGTH OF THE ONSHORE-DIRECTED 925-850 MB FLOW SHOULD ALLOW THE FRONT TO CONTINUE TO SLOWLY CHOP AWAY AT THE WEDGE AIR MASS OVER THE WESTERN PIEDMONT. OVERALL TEMPERATURE TREND TONIGHT IS FOR NEAR STEADY TO JUST A CATEGORY DROP TONIGHT IN THE EASTERN CWA`S WARM SECTOR... AND STEADILY RISING READINGS IN THE WESTERN CWA. MORNING READINGS SHOULD BE NEAR 50 IN THE TRIAD RANGING TO AROUND 60 TO LOWER 60S IN THE FAR EASTERN COUNTIES. DESPITE THE STIRRED BOUNDARY LAYER... ABUNDANT LOW LEVEL MOISTURE FAVORS DEVELOPMENT OF AREAS OF FOG... SOME OF IT POSSIBLY DENSE. REGARDING PRECIP CHANCES TONIGHT... DEEP ISENTROPIC UPGLIDE PERSISTS INTO TONIGHT WITH A STEADY MOIST INFLUX OF HIGH PRECIPITABLE WATER AIR AS NOTED ON THE CIRA BLENDED TPW PRODUCT. THIS PRODUCT ALSO SHOWS SOME DRIER AIR OFF TO OUR NORTHEAST WHICH THE MODELS AGREE WILL CONTINUE TO WRAP AROUND THE HIGH AND NOSE INTO NC COASTAL SECTIONS BY THIS EVENING. SO DESPITE THE LINGERING LOW LEVEL MOISTURE... WE SHOULD BE SEEING ENOUGH DRYING ALOFT IN THE EASTERN CWA TO SLIGHTLY REDUCE SHOWER COVERAGE IN THE EAST TONIGHT... PLUS THE FLOW BECOMES MORE PARALLEL TO THE ISENTROPES OVER EASTERN NC WHICH WILL REDUCE OVERALL LIFT. THE RIVER OF HIGH PRECIPITABLE WATER IS LIKELY TO BE SHUNTED WESTWARD OVER WRN NC HOWEVER SO HAVE HELD ONTO LIKELY POPS THERE... WITH HIGH CHANCES IN THE EASTERN CWA. RAINFALL TOTALS IN THE ONE QUARTER TO NEARLY THREE QUARTERS OF AN INCH RANGE SINCE LAST NIGHT ARE IMPRESSIVE CONSIDERING THE GENERALLY WEAK FORCING... BUT WITH PRECIPITABLE WATER OVER 200% OF NORMAL EXPECTED TO PERSIST... HAVE UPPED ADDITIONAL AMOUNTS TO A QUARTER TO THIRD OF AN INCH. -GIH && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 320 PM MONDAY... WEAK REMNANTS OF THE WEDGE REGIME MAY STILL BE HOLDING ON IN THE WINSTON-SALEM AREA AFTER SUNRISE TUESDAY... HOWEVER THIS SHOULD QUICKLY ERODE AND THE REST OF THE AREA WILL BE FIRMLY IN THE WARM SECTOR WITH STOUT SW FLOW AHEAD OF THE INCOMING COLD FRONT. FORCING FOR ASCENT SHOULD BEGIN TO IMPROVE TUESDAY MORNING AS A WEAK MID LEVEL PERTURBATION APPROACHES FROM THE WEST... BUT IN GENERAL THE LIFT MECHANISMS SHOULD BE DECREASING AS ISENTROPIC UPGLIDE WANES AND THE UPPER JET CORE HOLDS WELL TO OUR NORTH. FORECAST INSTABILITY IS MARGINAL WITH MODEL CONSENSUS MUCAPE VALUES ONLY AROUND 400-800 J/KG IN THE SOUTHEAST CWA... WHERE THE SREF PROBABILITY OF > 1000 J/KG OF CAPE IS LESS THAN 20%. WIND FIELDS ARE DECENT THOUGH WITH 850 MB WINDS SURPASSING 40 KTS. HAVE KEPT A MENTION OF THUNDER... MAINLY IN THE SOUTHEAST HALF OF THE AREA... BUT THE OVERALL RISK OF MORE THAN A COUPLE OF STRONG STORMS IS SMALL AND THREATS SHOULD BE LIMITED TO STRONG GUSTS. WILL HAVE HIGHS 69-75... REASONABLE CONSIDERING THICKNESSES ARE PROJECTED TO BE AROUND 30 M ABOVE NORMAL. THE COLD FRONT IS EXPECTED TO DROP SOUTHEASTWARD INTO THE NW PIEDMONT TUESDAY EVENING AND BE ORIENTED ACROSS THE SOUTHEAST CWA WEDNESDAY MORNING. HAVE KEPT CHANCE POPS FOR SHOWERS THROUGH TUESDAY NIGHT INTO WEDNESDAY MORNING... WITH FORCING LIMITED TO FRONTAL MASS CONVERGENCE. A CHILLY 1035 MB HIGH WILL PUSH IN FROM THE GREAT LAKES IN WHAT LOOKS TO BE ANOTHER DEVELOPING COLD AIR DAMMING EVENT. THIS HIGH SHOULD BE SOMEWHAT MODIFIED AS IT ARRIVES BUT WITH VERY COLD TEMPERATURES AND DEWPOINTS CURRENTLY BENEATH IT... IT SHOULD PACK ENOUGH OF A PUNCH OF COLD AIR TO HOLD HIGHS WEDNESDAY IN THE 60-65 DEGREE RANGE... AFTER LOWS OF 50-58. -GIH && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... AS OF 145 PM MONDAY... FORECAST CONFIDENCE CONTINUES TO INCREASE FOR THE THU-THU NIGHT PERIOD. A FRESH... INITIALLY DRY CLASSICAL COLD AIR DAMMING HIGH (1030 TO 1035 MB) WILL BUILD EASTWARD FROM THE EASTERN GREAT LAKES REGION WEDNESDAY EVENING REGION TO THE JERSEY COAST BY THURSDAY MORNING. FORECAST LOW LEVEL THICKNESSES DIP B/W 1320 AND 1340 METERS... WITH DRY SFC DEWPOINTS IN THE 25 TO 35 DEGREE RANGE BY 12Z THU. THIS WILL SET THE STAGE FOR ALMOST A MIRROR IMAGE OF TODAY... WITH STRONG ISENTROPIC LIFT (30 KT CROSS CONTOUR/TIGHT GRADIENT FLOW) IN THE 290-300 K LAYER AND ATOP THE SFC WEDGE... AND RESULT IN ANOTHER CLASSICAL DIABATICALLY ENHANCED CAD EVENT THURSDAY AND THURSDAY NIGHT. WILL ACCORDINGLY SHOW AN INCREASING CHANCE OF RAIN BEGINNING THURSDAY MORNING IN THE SOUTH AND EARLY AFTERNOON NORTH... CONTINUING THROUGH THE NIGHTTIME HOURS. HIGHS WILL STRUGGLE TO REACH 50 IN THE TRIAD... WITH LOWER 60S IN THE COASTAL PLAIN... EAST OF THE RETREATING CAD FRONT FROM THE COAST. FRI-FRI NIGHT... THE MEDIUM RANGE GUIDANCE IS STILL IN DISAGREEMENT REGARDING THE EVOLUTION OF THE UPPER TROUGH CURRENTLY NEAR 140W/35N IN THE EASTERN PACIFIC. THE LAST FEW CYCLES OF GFS QUICKLY ADVANCE THIS FEATURE ACROSS THE CONUS AND PLACES AN ATTENDANT SFC WAVE IN THE OHIO VALLEY AT 12Z FRI. THE LAST 2 ECMWF CYCLES... ON THE OTHER HAND... ARE MUCH SLOWER WITH THE PROGRESSION OF THE UPPER TROUGH AND ACCORDINGLY HOLD THE SFC WAVE OVER THE SOUTHERN PLAINS AT THAT TIME. GIVEN THE CONTINUED UNCERTAINTY... WILL CLOSELY FOLLOW HPC WITH SOMEWHAT OF A BLEND OF THESE TWO SOLUTIONS... WHICH WOULD RESULT IN THE SFC LOW ADVANCING THROUGH THE TN VALLEY FRIDAY... WITH AN ATTENDANT COLD FRONTAL PASSAGE THROUGH NC SATURDAY MORNING. THE PASSAGE OF THE LOW THROUGH THE TN VALLEY FRIDAY IS A CAD EROSION SCENARIO WHICH SHOULD LEAD TO THE DEMISE OF THE RESIDUAL CAD WEDGE FROM THURSDAY NIGHT. INCREASING SOUTHWESTERLY FLOW AHEAD OF THE LOW SHOULD BOOST HIGHS INTO THE 70S ACROSS THE FORECAST AREA... PERHAPS NEARING 80 IN THE COASTAL PLAIN. THERMAL PROFILES BECOME SUPPORTIVE OF DEEP CONVECTION FRIDAY AFTERNOON... BUT A LACK OF ANY DISCERNIBLE TRIGGER MAY PRECLUDE DEVELOPMENT UNTIL THE FRONT DRAWS NEARER LATER FRIDAY EVENING INTO THE OVERNIGHT. FORECAST CONFIDENCE FURTHER DECREASES THROUGH THE WEEKEND... AS THE GFS STALLS THE SFC FRONT JUST TO OUR SOUTH... WHERE IT INDUCES CYCLOGENESIS THAT RUNS UP THE COAST SATURDAY AND SATURDAY NIGHT. THIS IS A RESULT OF ANOTHER PROGRESSIVE TROUGH ALOFT WHOSE EVOLUTION THE MODELS DO NOT AGREE ON. WILL ACCORDINGLY STICK NEAR CLIMO IN THE SATURDAY THROUGH MONDAY TIME FRAME... AND MAINTAIN SILENT CHANCE POP. -MWS && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 740 AM MONDAY... CLASSICAL DIABATICALLY ENHANCED COLD AIR DAMMING EVENT AND ASSOCIATED IFR CONDITIONS CONTINUES FROM RDU WESTWARD... WITH A RAPIDLY ERODING WEDGE AIRMASS AND IMPROVING CIGS/VSBYS IN THE COASTAL PLAIN TO THE COAST. EXPECT THE INLAND RETREATING WEDGE FRONT TO STALL NEAR RDU THIS EVENING... SO WESTERN TAF SITES MAY REMAIN IN THE WEDGE AIRMASS THROUGH TUESDAY MORNING. SHOWERS WILL CONTINUE TO SPREAD NORTHWARD ACROSS THE FORECAST AREA AS ISENTROPIC LIFT MAXIMIZES THIS EVENING. EXPECT AREAS OF FOG... LOCALLY VERY DENSE... TO DEVELOP OVERNIGHT AS HIGHER DEWPOINTS CURRENTLY IN THE 60S AS FAR WEST AS SMITHFIELD CONTINUE TO SPREAD INLAND. VISIBILITIES MAY BE SOMEWHAT BETTER AT EASTERN SITES WHERE SOUTHEAST WINDS MAINTAIN MIXING... WHILE THE LOWEST VSBYS SHOULD OCCUR AT RDU AND POINTS WESTWARD. -MWS VISIBILITIES SHOULD REBOUND INTO THE VFR CATEGORY BY MIDDAY TUESDAY... AS THE AIR NEAR THE SURFACE BECOMES WELL MIXED AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. CEILINGS MAY BRIEFLY LIFT TO THE HIGH END OF MVFR OR LOW END OF VFR BY TUESDAY AFTERNOON. HEATING OF THE MOIST AND MARGINALLY UNSTABLE AIR MASS MAY LEAD TO THE DEVELOPMENT OF SCATTERED SHOWERS OR THUNDERSTORMS TUESDAY AFTERNOON. THESE STORMS MAY PERSIST INTO TUESDAY NIGHT AS A COLD FRONT CROSSES THE REGION. MAY SEE ANOTHER COLD AIR DAMMING EVENT WITH ASSOCIATED LOW CEILINGS/VISIBILITIES THUR-THUR NIGHT AS ANOTHER STRONG SFC HIGH PRESSURE BUILDS ACROSS THE NORTHERN MID ATL REGION. ANOTHER COLD FRONT IS EXPECTED TO APPROACH FROM THE WEST FRIDAY AFTERNOON...AND CROSS THE AREA EARLY SATURDAY. THIS COULD RESULT IN MORE UNSETTLED WEATHER AT THAT TIME. -MWS/WSS && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...MWS AVIATION...MWS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
310 PM EDT MON MAR 31 2008 .SYNOPSIS...COOL HIGH PRESSURE WILL CONTINUE SHIFTING EAST OVER THE WESTERN ATLANTIC TONIGHT... AS A WARM FRONT SURGES WESTWARD THROUGH THE AREA OVERNIGHT... ALLOWING MUCH WARMER AIR TO PUSH INLAND FROM THE COAST. THIS WARMER AIR WILL ENGULF THE ENTIRE AREA TUESDAY AS A MILD SOUTHWEST FLOW TAKES OVER. A COLD FRONT WILL APPROACH FROM THE WEST LATE TUESDAY AND CROSS THE AREA TUESDAY NIGHT. ANOTHER COOL HIGH PRESSURE AREA WILL BUILD IN FROM THE NORTH ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 255 PM MONDAY... THE FORMER COASTAL FRONT... DEMARKING THE LEADING EDGE OF THE SLOWLY ERODING WEDGE AIR MASS... HAS SURGED WELL INLAND THROUGH THE COASTAL PLAIN... AND TEMPERATURES ON ITS EAST SIDE HAVE RISEN WELL INTO THE 60S. READINGS WITHIN THE COLD DOME HAVE CLIMBED VERY MODESTLY... A DEGREE AN HOUR OR SO... AND STILL SIT IN THE MID 40S TO LOWER 50S. HOWEVER THE SURFACE FLOW WITHIN THE HEART OF THE COLD DOME OVER NC HAS TAKEN ON A MORE NORTHERLY COMPONENT... AN EARLY INDICATOR THAT THE DOME IS BEGINNING TO DRAIN... AND THIS IS VERIFIED BY A STEADY WARMING IN THE SURFACE-925 MB LAYER NOTED ON AREA AMDAR AIRCRAFT SOUNDING DATA. THE DAMMING PARENT HIGH... NOW CENTERED WELL TO OUR NE OVER THE WESTERN ATLANTIC... HAS LOST ITS MID LEVEL SUPPORT. WITH THE STEADY FEED OF DRY AIR INTO THE WEDGE NOW CUT OFF... EVAPORATIVE COOLING PROCESSES IN THE COLD DOME HAVE CEASED... HENCE THE SLOW BUT STEADY RISE IN TEMPS IN THE LAST FEW HOURS. WHILE THE STRONG WARM ADVECTION ATOP THE COLD DOME WILL HELP KEEP THE STABLE SURFACE BASED LAYER SUFFICIENTLY STRONG TO SLOW THE WESTWARD INSURGENCE OF THE COASTAL FRONT... THE STRENGTH OF THE ONSHORE-DIRECTED 925-850 MB FLOW SHOULD ALLOW THE FRONT TO CONTINUE TO SLOWLY CHOP AWAY AT THE WEDGE AIR MASS OVER THE WESTERN PIEDMONT. OVERALL TEMPERATURE TREND TONIGHT IS FOR NEAR STEADY TO JUST A CATEGORY DROP TONIGHT IN THE EASTERN CWA`S WARM SECTOR... AND STEADILY RISING READINGS IN THE WESTERN CWA. MORNING READINGS SHOULD BE NEAR 50 IN THE TRIAD RANGING TO AROUND 60 TO LOWER 60S IN THE FAR EASTERN COUNTIES. DESPITE THE STIRRED BOUNDARY LAYER... ABUNDANT LOW LEVEL MOISTURE FAVORS DEVELOPMENT OF AREAS OF FOG... SOME OF IT POSSIBLY DENSE. REGARDING PRECIP CHANCES TONIGHT... DEEP ISENTROPIC UPGLIDE PERSISTS INTO TONIGHT WITH A STEADY MOIST INFLUX OF HIGH PRECIPITABLE WATER AIR AS NOTED ON THE CIRA BLENDED TPW PRODUCT. THIS PRODUCT ALSO SHOWS SOME DRIER AIR OFF TO OUR NORTHEAST WHICH THE MODELS AGREE WILL CONTINUE TO WRAP AROUND THE HIGH AND NOSE INTO NC COASTAL SECTIONS BY THIS EVENING. SO DESPITE THE LINGERING LOW LEVEL MOISTURE... WE SHOULD BE SEEING ENOUGH DRYING ALOFT IN THE EASTERN CWA TO SLIGHTLY REDUCE SHOWER COVERAGE IN THE EAST TONIGHT... PLUS THE FLOW BECOMES MORE PARALLEL TO THE ISENTROPES OVER EASTERN NC WHICH WILL REDUCE OVERALL LIFT. THE RIVER OF HIGH PRECIPITABLE WATER IS LIKELY TO BE SHUNTED WESTWARD OVER WRN NC HOWEVER SO HAVE HELD ONTO LIKELY POPS THERE... WITH HIGH CHANCES IN THE EASTERN CWA. RAINFALL TOTALS IN THE ONE QUARTER TO NEARLY THREE QUARTERS OF AN INCH RANGE SINCE LAST NIGHT ARE IMPRESSIVE CONSIDERING THE GENERALLY WEAK FORCING... BUT WITH PRECIPITABLE WATER OVER 200% OF NORMAL EXPECTED TO PERSIST... HAVE UPPED ADDITIONAL AMOUNTS TO A QUARTER TO THIRD OF AN INCH. -GIH && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 300 AM MONDAY... SOME PRECIPITATION MAY BE ONGOING EARLY TUESDAY MORNING IN THE VICINITY OF THE RESIDUAL WEDGE FRONT ACROSS THE NW PIEDMONT. THE NAM MAINTAINS A BETTER DEPICTION OF THIS BOUNDARY WHILE THE GFS APPEARS TOO QUICK TO WASH IT OUT. FEEL THE NAM AND ITS BETTER RESOLUTION IS HELPING IT TO RESOLVE THE LIKELY SCENARIO OF THE BOUNDARY STILL BEING WELL DEFINED OVER THE NW PIEDMONT. THE BOUNDARY SHOULD BEGIN TO MIX OUT AFTER SUNRISE TUESDAY AS SOUTHWESTERLY LOW LEVEL FLOW INCREASES AHEAD OF AN APPROACHING COLD FRONT. THE ENTIRE REGION WILL BE IN THE WARM SECTOR WITH TEMPS CLIMBING INTO THE UPPER 60S NW TO LOW TO MID 70S FURTHER EAST. DEWPOINTS ARE ALSO FORECAST TO CLIMB INTO THE UPPER 50S AND LOWER 60S WHICH APPEAR EASILY ATTAINABLE AS THE NEAR SFC FLOW ORIGINATES FROM THE ATLANTIC WATERS JUST OFF THE GA/FL COAST WHERE MID TO UPPER 60 DEWPOINTS CURRENTLY RESIDE. PRECIPITABLE WATERS ARE ALSO FORECAST TO CLIMB TO AROUND 200% ABOVE NORMAL WITH VALUES APPROACH 1.3 INCHES. WITH THESE CONDITIONS IN PLACE...MUCAPES ARE FORECAST TO INCREASE BETWEEN 500-1000 J/KG... ESPECIALLY ACROSS THE COASTAL PLAIN AND THE SANDHILLS. WITH A MOIST AND SOMEWHAT UNSTABLE AIRMASS IN PLACE...IT WILL NOT TAKE MUCH TO INITIATE CONVECTION. THE ECMWF/GFS/NAM ALL SHOW A LEAD SHORTWAVE THAT MOVES ACROSS THE REGION MIDDAY TUESDAY WELL AHEAD OF THE MAIN COLD FRONT AND THE MAIN MID LEVEL TROUGH. THIS SHOULD PROVIDE ENOUGH LIFT TO GENERATE SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE AREA WITH THE BEST POTENTIAL ACROSS THE EASTERN ZONES WHERE THE BEST INSTABILITY SHOULD BE ESTABLISHED. ANY CONVECTION THAT INITIATES COULD PRODUCE LOCALLY HEAVY RAINFALL GIVEN THE HIGH PRECIPITABLE WATERS IN PLACE. 0-6KM BULK SHEAR VALUES ARE NOT VERY IMPRESSIVE... AVERAGING 20-25KT...BUT A FEW STORMS COULD PRODUCE GUSTY WINDS WITH 35-40KT PRESENT IN THE LOW LEVELS. THE MAIN COLD FRONT SHOULD ENTER THE WESTERN PIEDMONT AROUND 00Z WED AND BE SOUTH AND EAST OF THE AREA BY 12Z. THE FRONT WILL NOT HAVE MUCH UPPER LEVEL SUPPORT TO WORK WITH GIVEN THE MAIN MID LEVEL TROUGH STAYS WELL NORTH OVER THE GREAT LAKES AND NEW ENGLAND. PRECIP GENERATION WILL BE DRIVEN BY LOW LEVEL CONVERGENCE INTERACTING WITH A MOIST AIRMASS AND POSSIBLY SOME RESIDUAL INSTABILITY IN THE EVENING. THEREFORE...EXPECT A BAND OF PRIMARILY SHOWERS WITH PERHAPS A FEW RUMBLES OF THUNDER TO ACCOMPANY THE FRONTAL PASSAGE. RAINFALL TOTALS WITH THE FRONT SHOULD BE LIGHT...AVERAGING LESS THAN A QUARTER OF AN INCH. THE COOLER AIR WILL LIKELY BE DELAYED BEHIND THE FRONT DUE TO THE MOUNTAINS...SO A DRAMATIC COOL DOWN IS NOT EXPECTED. IN GENERAL EXPECT LOWS IN THE 50-57 RANGE. -JFB && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... AS OF 145 PM MONDAY... FORECAST CONFIDENCE CONTINUES TO INCREASE FOR THE THU-THU NIGHT PERIOD. A FRESH... INITIALLY DRY CLASSICAL COLD AIR DAMMING HIGH (1030 TO 1035 MB) WILL BUILD EASTWARD FROM THE EASTERN GREAT LAKES REGION WEDNESDAY EVENING REGION TO THE JERSEY COAST BY THURSDAY MORNING. FORECAST LOW LEVEL THICKNESSES DIP B/W 1320 AND 1340 METERS... WITH DRY SFC DEWPOINTS IN THE 25 TO 35 DEGREE RANGE BY 12Z THU. THIS WILL SET THE STAGE FOR ALMOST A MIRROR IMAGE OF TODAY... WITH STRONG ISENTROPIC LIFT (30 KT CROSS CONTOUR/TIGHT GRADIENT FLOW) IN THE 290-300 K LAYER AND ATOP THE SFC WEDGE... AND RESULT IN ANOTHER CLASSICAL DIABATICALLY ENHANCED CAD EVENT THURSDAY AND THURSDAY NIGHT. WILL ACCORDINGLY SHOW AN INCREASING CHANCE OF RAIN BEGINNING THURSDAY MORNING IN THE SOUTH AND EARLY AFTERNOON NORTH... CONTINUING THROUGH THE NIGHTTIME HOURS. HIGHS WILL STRUGGLE TO REACH 50 IN THE TRIAD... WITH LOWER 60S IN THE COASTAL PLAIN... EAST OF THE RETREATING CAD FRONT FROM THE COAST. FRI-FRI NIGHT... THE MEDIUM RANGE GUIDANCE IS STILL IN DISAGREEMENT REGARDING THE EVOLUTION OF THE UPPER TROUGH CURRENTLY NEAR 140W/35N IN THE EASTERN PACIFIC. THE LAST FEW CYCLES OF GFS QUICKLY ADVANCE THIS FEATURE ACROSS THE CONUS AND PLACES AN ATTENDANT SFC WAVE IN THE OHIO VALLEY AT 12Z FRI. THE LAST 2 ECMWF CYCLES... ON THE OTHER HAND... ARE MUCH SLOWER WITH THE PROGRESSION OF THE UPPER TROUGH AND ACCORDINGLY HOLD THE SFC WAVE OVER THE SOUTHERN PLAINS AT THAT TIME. GIVEN THE CONTINUED UNCERTAINTY... WILL CLOSELY FOLLOW HPC WITH SOMEWHAT OF A BLEND OF THESE TWO SOLUTIONS... WHICH WOULD RESULT IN THE SFC LOW ADVANCING THROUGH THE TN VALLEY FRIDAY... WITH AN ATTENDANT COLD FRONTAL PASSAGE THROUGH NC SATURDAY MORNING. THE PASSAGE OF THE LOW THROUGH THE TN VALLEY FRIDAY IS A CAD EROSION SCENARIO WHICH SHOULD LEAD TO THE DEMISE OF THE RESIDUAL CAD WEDGE FROM THURSDAY NIGHT. INCREASING SOUTHWESTERLY FLOW AHEAD OF THE LOW SHOULD BOOST HIGHS INTO THE 70S ACROSS THE FORECAST AREA... PERHAPS NEARING 80 IN THE COASTAL PLAIN. THERMAL PROFILES BECOME SUPPORTIVE OF DEEP CONVECTION FRIDAY AFTERNOON... BUT A LACK OF ANY DISCERNIBLE TRIGGER MAY PRECLUDE DEVELOPMENT UNTIL THE FRONT DRAWS NEARER LATER FRIDAY EVENING INTO THE OVERNIGHT. FORECAST CONFIDENCE FURTHER DECREASES THROUGH THE WEEKEND... AS THE GFS STALLS THE SFC FRONT JUST TO OUR SOUTH... WHERE IT INDUCES CYCLOGENESIS THAT RUNS UP THE COAST SATURDAY AND SATURDAY NIGHT. THIS IS A RESULT OF ANOTHER PROGRESSIVE TROUGH ALOFT WHOSE EVOLUTION THE MODELS DO NOT AGREE ON. WILL ACCORDINGLY STICK NEAR CLIMO IN THE SATURDAY THROUGH MONDAY TIME FRAME... AND MAINTAIN SILENT CHANCE POP. -MWS && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 740 AM MONDAY... CLASSICAL DIABATICALLY ENHANCED COLD AIR DAMMING EVENT AND ASSOCIATED IFR CONDITIONS CONTINUES FROM RDU WESTWARD... WITH A RAPIDLY ERODING WEDGE AIRMASS AND IMPROVING CIGS/VSBYS IN THE COASTAL PLAIN TO THE COAST. EXPECT THE INLAND RETREATING WEDGE FRONT TO STALL NEAR RDU THIS EVENING... SO WESTERN TAF SITES MAY REMAIN IN THE WEDGE AIRMASS THROUGH TUESDAY MORNING. SHOWERS WILL CONTINUE TO SPREAD NORTHWARD ACROSS THE FORECAST AREA AS ISENTROPIC LIFT MAXIMIZES THIS EVENING. EXPECT AREAS OF FOG... LOCALLY VERY DENSE... TO DEVELOP OVERNIGHT AS HIGHER DEWPOINTS CURRENTLY IN THE 60S AS FAR WEST AS SMITHFIELD CONTINUE TO SPREAD INLAND. VISIBILITIES MAY BE SOMEWHAT BETTER AT EASTERN SITES WHERE SOUTHEAST WINDS MAINTAIN MIXING... WHILE THE LOWEST VSBYS SHOULD OCCUR AT RDU AND POINTS WESTWARD. -MWS VISIBILITIES SHOULD REBOUND INTO THE VFR CATEGORY BY MIDDAY TUESDAY... AS THE AIR NEAR THE SURFACE BECOMES WELL MIXED AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. CEILINGS MAY BRIEFLY LIFT TO THE HIGH END OF MVFR OR LOW END OF VFR BY TUESDAY AFTERNOON. HEATING OF THE MOIST AND MARGINALLY UNSTABLE AIR MASS MAY LEAD TO THE DEVELOPMENT OF SCATTERED SHOWERS OR THUNDERSTORMS TUESDAY AFTERNOON. THESE STORMS MAY PERSIST INTO TUESDAY NIGHT AS A COLD FRONT CROSSES THE REGION. MAY SEE ANOTHER COLD AIR DAMMING EVENT WITH ASSOCIATED LOW CEILINGS/VISIBILITIES THUR-THUR NIGHT AS ANOTHER STRONG SFC HIGH PRESSURE BUILDS ACROSS THE NORTHERN MID ATL REGION. ANOTHER COLD FRONT IS EXPECTED TO APPROACH FROM THE WEST FRIDAY AFTERNOON...AND CROSS THE AREA EARLY SATURDAY. THIS COULD RESULT IN MORE UNSETTLED WEATHER AT THAT TIME. -MWS/WSS && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...MWS AVIATION...MWS
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
949 AM CDT SUN MAR 30 2008 .DISCUSSION...WILL ALLOW WIND ADVISORY TO EXPIRE AT 10 AM. SEE NO WAY WIND SPEEDS CAN GET STRONGER...AND ALL SITES NOW AOB WIND ADVISORY CRITERIA. SFC PRESSURE GRADIENT WILL RELAX...AND 925MB WIND SPEEDS DIMINISH THROUGH THE DAY. BIGGEST CHALLENGE TODAY WILL BE CLOUD COVER AND RELATED TEMPERATURES. HIGH CLOUDS WILL MOVE IN FROM THE SOUTH...BUT THESE WILL BE THIN AND PROBABLY WOULD NOT AFFECT TEMPS TOO MUCH. LOWER COLD AIR ADVECTION CLOUDS...NOW ACROSS THE FA...WOULD AFFECT TEMPS. TAMDAR SOUNDINGS INDICATE CLOUD LAYER IS THIN...ABOUT 100FT. THINK THESE CLOUDS WILL REMAIN MUCH OF THE DAY...BUT BREAK UP TOWARDS LATE AFTERNOON AS SFC RIDGE BUILDS INTO THE AREA. CURRENT TEMPS ALREADY INTO THE 30S...SO MAX TEMP FORECAST LOW 40S ACROSS THE SOUTH TO MID 30S ACROSS THE NORTH REASONABLE. && .AVIATION...CIGS HAVE DROPPED TO 20 TO 30 HUNDRED FT ACROSS THE AREA. SHOULD REMAIN THAT WAY MOST OF THE DAY. STRONG WINDS THIS MORNING SHOULD TAPER OFF BY LATE MORNING. && .PREV DISCUSSION... /ISSUED 430 AM CDT SUN MAR 30 2008/ DISCUSSION...TODAY THROUGH TUESDAY NIGHT PROGRESSIVE UPPER AIR PATTERN CONTINUES ACROSS NORTH AMERICA. SPLIT FLOW WAS ACROSS NORTH AMERICA WITH NORTHERN STREAM OVER NORTHERN STATES/SOUTHERN CANADA AND SOUTHERN STREAM OVER CENTRAL PLAINS. NAM AND GFS WERE SIMILAR THROUGH 84 HOURS. HOWEVER NAM WAS BETTER WITH QPF FOR THIS MORNINGS SYSTEM AND WILL BE USED INITIALLY. GOOD PRESSURE RISE FALL COUPLET ORIENTATED NORTHEAST SOUTHWEST WILL MOVE TO THE NORTHEAST THIS MORNING. SURFACE MIXING RATIOS FELL THE BEST OVER WESTERN SD OTHERWISE RATIOS WERE HIGHEST DOWN THE RED RIVER AND WERE SHIFTING EAST. MODELS LOWER MIXING RATIOS FROM THE NORTHWEST TODAY. SURFACE LOW PRESSURE NORTH OF ROLLA ND WILL MOVE INTO NORTHERN ONTARIO BY THIS AFTERNOON. SATELLITE SHOWING SOME DRYING/DARKENING MOVING AS SHORT WAVE/JET STREAK MOVE THROUGH THE AREA. 850 HPA WINDS FORECAST AROUND 50 KNOTS THIS MORNING WITH 110 KNOT UPPER LEVEL JET OVERHEAD. RESPECTABLE COLD ADVECTION ALOFT THIS MORNING. FAIRLY UNIDIRECTIONAL FLOW THROUGH 700 HPA. FAIR AMOUNT OF DRYING IN THE 1000 TO 500 HPA LAYER. SURFACE GEOSTROPHIC WINDS AROUND 40-50 KNOTS THIS MORNING. SURFACE LOW PRESSURE HAS DROPPED TO 996 MB AND WAS A COUPLE MB BELOW CURRENT MODEL FORECAST. PRESSURE RISE CENTER FORECAST TO PASS THROUGH THE AREA BY NOON TODAY. WINDS AND FORCING DROP OFF FAST BY NOON. SURFACE OBS GETTING WIND GUST 35 KNOTS IN WESTERN ND. SO WILL EXPAND AND EXTEND WIND ADVISORY THROUGH 10 AM. NEXT SYSTEM TO AFFECT THE SOUTHERN ZONES MAINLY MON MAY SEE A FEW INCHES OF SNOW IN FAR SOUTHERN ZONES. SURFACE RIDGE WILL DRIVE COOLER/DRIER AIR OUT OF CANADA FOR MON. EXTENDED...WEDNESDAY AND THURSDAY ANOTHER ROUND OF SNOW POSSIBLE FOR WED IN THE SOUTHERN ZONES AS MOISTURE RETURNS NORTH WED. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG
AREA FORECAST DISCUSSION
NWS SEATTLE WA
335 PM PDT MON MAR 31 2008 .SYNOPSIS...A WEAK UPPER LEVEL DISTURBANCE MOVING THROUGH THE AREA THIS EVENING WILL KEEP SHOWERS IN THE FORECAST. DRY NORTHERLY FLOW WILL PREVAIL OVER THE AREA TUESDAY. ANOTHER DISTURBANCE WILL BRING AN INCREASE IN CLOUDS TUESDAY EVENING ALONG WITH A SLIM THREAT OF SHOWERS NEAR THE CASCADE CREST. AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA ON WEDNESDAY AND REMAIN THROUGH THURSDAY RETURNING TEMPERATURES TO NEAR NORMAL WITH PLENTY OF SUNSHINE. THE RIDGE WILL WEAKEN ON FRIDAY WITH MORE UNSETTLED WEATHER EXPECTED THIS WEEKEND. && .SHORT TERM...SATELLITE IMAGERY AND WSR-88D SHOWING SHOWER ACTIVITY INCREASING OVER WESTERN WASHINGTON THIS AFTERNOON. WESTERLY FLOW ALOFT HAS RAINSHADOW THE CENTRAL SOUND A BIT THIS AFTERNOON BUT ACARS SOUNDINGS SHOW WINDS AT 700 MB BECOMING MORE NORTHWESTERLY SO EXPECT THE POSSIBILITY OF SHOWERS EVEN IN THE METRO AREA. MODEL SOUNDINGS LIFTED INDEXES WERE IN THE 0 TO PLUS 2 RANGE BUT BUFR SOUNDINGS INDICATE LIFTED INDEXES NEAR 0 OF SLIGHTLY NEGATIVE EARLY THIS EVENING. ACARS SOUNDINGS REPORTING 500 MB TEMPERATURES STILL VERY COLD -36C. WITH THESE VARIABLES A THUNDERSTORM CAN NOT BE RULED OUT THIS EVENING WITH SMALL HAIL ALSO A POSSIBILITY. HAVE ADD THIS TO THE FORECAST. ONCE THE UPPER LEVEL DISTURBANCE MOVES THROUGH THIS EVENING 00Z-06Z...FLOW ALOFT BECOMING MORE NORTHERLY WITH THE AMS DRYING OUT. THIS WILL ALLOW TEMPERATURES TO ONCE AGAIN DROP BELOW FREEZING IN MOST LOCATIONS. TUESDAY A BIT OF A TRANSITION DAY WITH A SURFACE AND UPPER LEVEL RIDGE BUILDING OFF THE COAST. NORTHERLY FLOW ALOFT CONTINUING OVER THE AREA WITH A VERY WEAK UPPER LEVEL FEATURE MOVING THROUGH LATE IN THE DAY. AT THIS POINT THIS FEATURE LOOKS DRY FOR THE MOST PART WITH JUST A CHANCE OF SHOWERS NEAR THE CASCADE CREST. WEDNESDAY THE UPPER LEVEL RIDGE STARTS TO SHIFT OVER WESTERN WASHINGTON WITH NORTHWESTERLY SURFACE GRADIENTS. DAYTIME TEMPERATURES WARMING BACK TO NEAR NORMAL VALUES...MID 50S...WITH PLENTY OF SUNSHINE. SAME STORY ON THURSDAY ALTHOUGH BY THURSDAY AFTERNOON THE UPPER LEVEL RIDGE STARTS TO WEAKEN MARKING THE BEGINNING OF THE END OF THE SHORT STRETCH OF DRY WEATHER. CLIMATE NOTE...THIS HAS BEEN THE COLDEST LAST WEEK OF MARCH ON RECORD AT SEATTLE TACOMA AIRPORT IN TERMS OF AVERAGE HIGH TEMPERATURES. DEPENDING ON WHAT THE HIGH IS TODAY IT WILL BE THE SECOND OR THIRD COLDEST USING ALL OF THE RECORDS FOR SEATTLE INCLUDING THE FEDERAL BUILDING RECORDS WHICH GO BACK TO 1891. A PNS WILL BE SENT OUT LATER THIS AFTERNOON WITH SOME EXACT FIGURES. FELTON .LONG TERM...NOT A LOT OF CONSISTENCY IN THE LONG TERM MODELS. ON FRIDAY THE UPPER LEVEL RIDGE CONTINUES TO WEAKEN WITH INCREASING ONSHORE FLOW AT THE SURFACE EURO AND THE GFS ARE DRY WHILE THE CANADIAN DEVELOPS SOME LIGHT PRECIP OVER THE AREA. LOOKS LIKE A MARINE PUSH TYPE OF DAY AND WITH A WEAK UPPER LEVEL TROUGH STILL OFFSHORE EVEN ON THE CANADIAN MODEL WILL KEEP THE FORECAST DRY BUT INDICATE MOSTLY CLOUDY CONDITIONS. THE MODEL DON`T SHOW A LOT OF AGREEMENT BEYOND FRIDAY EITHER WITH THE EURO MODEL BRING A SHORTWAVE THROUGH ON SATURDAY WHILE THE CANADIAN AND GFS ARE SLOWER AND WEAKER WITH THIS FEATURE. UPPER LEVEL TROUGH BEHIND THE SHORTWAVE DEVELOPING OVER THE EASTERN PACIFIC. EURO IS ALSO MUCH STRONGER AND MUCH SLOWER BRINGING THIS FEATURE THROUGH WESTERN WASHINGTON VERSUS THE GFS...MONDAY TROUGH PASSAGE VERSUS SUNDAY. FOR NOW WILL STAY WITH THE BROADBRUSH CHANCE POPS FROM FRIDAY THROUGH MONDAY. FELTON .AVIATION...A BROAD CONVERGENCE ZONE REMAINS OVER WRN SNOHOMISH THIS AFTERNOON BUT SHOWING SIGNS OF SAGGING A BIT SWD. MODELS SHIFT THE CONVERGENCE ZONE SOUTH TO ALONG THE KING/SNOHOMISH COUNTY LINE OR PERHAPS FAR NORTH KING COUNTY AFTER 00Z (PIC10). HOWEVER...IT NOW LOOKS UNLIKELY THAT IT WILL GET ALL THE WAY DOWN TO THE KBFI-KSEA TERMINALS. HOWEVER...UNORGANIZED SCATTERED SHOWERS COULD HIT JUST ABOUT ANYWHERE WITH SOME SMALL HAIL/ICE PELLETS MIXED IN. ISOLATED TSTMS POSSIBLE. SHOWERS/TSTMS ENDING AFTER SUNSET. KSEA...WINDS LIKELY TO REMAIN SOUTHERLY 6-10 KT...BUT COULD GO LIGHT OR ELY FROM 03-06Z IF THE PSCZ STALLS CLOSE ENOUGH TO THE NORTH. LESS THAN A 20 PERCENT CHANCE THAT THE PSCZ WILL MOVE SOUTH THROUGH THE TERMINALS WITH A WIND SHIFT TO THE NORTH. && .MARINE...A WEAK SURFACE TROUGH WILL SWING THROUGH THE AREA THIS EVENING. THIS MAY INDUCE ENOUGH WLY GRADIENT THROUGH THE STRAIT FOR SCA CONDITIONS. IN ADDITION...WINDS ALONG THE N COAST MAY PICK UP TO SCA BRIEFLY AS WELL. WINDS WILL RAPIDLY DIE DOWN TO LESS THAN 10 KT BY LATE THIS EVENING. SURFACE RIDGE RETURNS LATE TONIGHT AND TUE (PIC11) FOR GENERALLY LIGHT WINDS. DTM && .SEW WATCHES/WARNINGS/ADVISORIES... .SMALL CRAFT ADVISORY ENTIRE STRAIT AND THE COAST THROUGH 9 PM. $$ WEATHER.GOV/SEATTLE
AREA FORECAST DISCUSSION...UPDATE
NWS MARQUETTE MI
125 AM EDT TUE APR 1 2008 UPDATED FOR AVIATION ...LATE SEASON WINTER STORM MOVING INTO UPPER MICHIGAN WITH BLIZZARD CONDITIONS POSSIBLE OVER THE NORTH CENTRAL TUE MORNING... ...TRAVEL STRONGLY DISCOURAGED THROUGH TUE MORNING... .UPDATE... ADDED MENTION OF ELEVATED TS TO SRN MNM COUNTY IN ADVANCE OF CLUSTER OF CNVCTN MOVING NE THRU CNTRL WI WHERE 18Z NAM F6 SHOWS H7-5 LAPSE RATES APRCHG 7C/KM JUST TO THE N OF H85 WARM FNT. && .SYNOPSIS... 20Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED UPPER LEVEL TROUGHING OVER THE NORTHWEST U.S. INTO THE NRN PLAINS AND STRONG RIDGING ALONG THE EAST COAST. WITHIN THE TROUGH...TWO MAIN FEATURES ARE EVIDENT FOR THE WINTER STORM. FIRST IS A SHRTWV OVER ERN NEBRASKA AND THE SECOND IS AN UPPER LEVEL LOW OVER RIVERTON WY. DPVA AHEAD OF THE ERN NEBRASKA SHRTWV...STRONG WARM ADVECTION OF MOISTURE INTO THE UPPER MIDWEST (PRECIPITABLE WATER VALUES NEAR 200 PCT OF NORMAL PER 12Z RAOBS)...AND UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 130 KT JET STRETCHING FROM NE MN INTO NORTHERN ONTARIO...HAS LED TO THE DEVELOPMENT OF A DEFORMATION ZONE OF MOSTLY LIGHT TO MODERATE PCPN FROM CENTRAL/SRN MN THROUGH MUCH OF WI AND NOW INTO THE WI BORDER AREAS. WITHIN THIS ZONE...THERE IS A POCKET OF HEAVIER PCPN WHICH HAS BEEN WELL ADVERTISED NEAR WAUSUA MOVING NE. SOME LIGHTNING HAS EVEN BEEN DETECTED WITHIN THIS HEAVIER PCPN. RAIN/SNOW/SLEET LINE IS SITUATED FROM ROCHESTER MN TO JUST SOUTH OF WAUSAU AND INTO SRN MENOMINEE COUNTY. RECENT CALLS HAVE FOUND RAIN IN MENOMINEE AND ESCANABA. SURFACE LOW ASSOCIATED WITH ALL THIS PCPN CURRENTLY NEAR INDIANOLA IA WITH A PRESSURE AROUND 999MB. COMPARISON WITH MODEL DATA APPEARS THAT THE NAM MAY BE DOING A BETTER JOB WITH THE STRENGTH COMPARED TO THE GFS. TO THE NORTHWEST...1030MB HIGH PRESSURE IS SITUTATED OVER MANITOBA. 850MB TEMPS ARE SOMEWHAT COLD AHEAD OF THIS HIGH...WITH 12Z RAOBS SHOWING -7C AT INL AND -10C AT CWPL...SO THERE IS SOME COLDER AIR TO FILTER INTO THE AREA. OVER THE CWA...SNOW HELD OFF FOR MUCH OF THE MORNING AND EARLY AFTERNOON DUE TO DRY AIR IN THE 700-900MB LAYER AS SEEN ON TAMDAR SOUNDINGS (DEWPOINT DEPRESSIONS AROUND 10C). && .SHORT TERM (TONIGHT AND TUE)... MODELS ARE NOW IN GOOD AGREEMENT WITH REGARDS TO THE TRACK OF THE LOW PRESSURE SYSTEM AS IT LIFTS ACROSS NORTHERN LAKE HURON TUE MORNING. AFTER NOTICING THAT THE GFS IS A BIT TOO WEAK WITH THE SYSTEM CURRENTLY FOR ONLY A 6 HOUR FORECAST...HAVE FOLLOWED A BIT CLOSER THE 12Z NAM/LOCAL WRF-ARW/RUC 13 MODELS WHICH ARE SLIGHTLY DEEPER. SHOULD NOTE THAT THE NEW 18Z NAM LOOKS EVEN BETTER WITH THE CURRENT STRENGTH...AND DISPLAYS EVEN MORE PCPN FOR THE CWA THAN THE GOING FORECAST. DETAILS...SHRTWV OVER ERN NEBRASKA WILL CONTINUE LIFTING NORTHEAST TONIGHT. HOWEVER...THE UPPER LOW OVER WYOMING IS PROGGED TO CATCH UP WITH THIS SHRTWV...RESULTING IN A PHASING OF THE TWO FEATURES BASICALLY OVER THE CWA AROUND 12Z. THIS PHASING WILL CAUSE THE LOW TO DEEPEN MORE AFTER 06Z...TO SOMEWHERE AROUND 993MB OVER NRN LK HURON BY 12Z TUE. UNTIL THE PHASING OCCURS...THERE ARE TWO PERIODS OF CONCERN. FOR LATE THIS AFTERNOON AND EVENING...DEFORMATION ZONE WILL ENVELOP MUCH OF UPPER MICHIGAN BY 22Z AS THE STRONG 700-600MB FRONTOGENESIS ZONE AND UPPER JET SHIFT EAST. AREA OF HVY PCPN LIKELY TO GO ACROSS THE SOUTH CENTRAL U.P.. A REPORT OF AN INCH PER HOUR CAME IN FROM MARSHFIELD AND 2 INCHES PER HOUR IN WAUSAU...AND THIS SHOULD EASILY OCCUR IN NORTHERN MENOMINEE COUNTY WHERE SOUNDING PROFILES ARE SHOWN TO STAY SOLIDLY BELOW FREEZING. IN SRN MENOMINEE COUNTY AND OTHER AREAS ALONG LAKE MICHIGAN UP INTO LUCE COUNTY... SOUNDINGS ARE A LITTLE LESS CERTAIN...WITH SNOW...SLEET OR RAIN ALL POSSIBLE. THERE WAS A REPORT OF SLEET ACCUMULATING ON THE GROUND AT WAUSAU...SO WOULD NOT BE SURPRISED TO SEE THE SAME IN SRN MENOMINEE COUNTY. OVER THE REST OF THE CWA...SNOWFALL ACCUMULATION RATES OF ONE HALF OF AN INCH TO AN INCH PER HOUR SEEM LIKELY UNDER THE DEFORMATION ZONE. THUS...GOING WARNINGS LOOK FINE. AFTER MIDNIGHT...THE UPPER JET FORCING EXITS...BUT THE PHASING BEGINS TO OCCUR. PV AND THETA-E PLOTS ACTUALLY SUGGEST THE DEVELOPMENT OF THE FULL-FLEDGED TROWAL TOWARDS LATE IN THE NIGHT...WHICH SHOULD HELP KEEP SOME LIGHT TO MODERATE BANDED PCPN GOING OVER THE CWA. COMBINE THIS WITH COLD ADVECTION ON THE BACK SIDE OF THE LOW AND A GOOD SETUP IS IN PLACE FOR LAKE ENHANCEMENT/UPSLOPE. WITH WINDS OUT OF THE NORTH TO NORTHEAST...AND STRONG AT THAT (900MB WINDS PROGGED AT 50 KT BY 12Z)...UPSLOPE SHOULD BE REALLY STRONG OVER THE HIGHER TERRAIN OF THE FAR WEST AND NORTH CENTRAL. TIMING OF THE BEST SNOW...BASED ON 900MB TEMPS THAT CORRELATED WELL WITH THE APRIL 4 2007 BLIZZARD (AROUND -8C TO START UPSLOPE) SUGGESTS BETWEEN 06-09Z OUT WEST AND 09-12Z OVER THE NORTH CENTRAL. WOULD NOT BE SURPRISED TO SEE INCH PER HOUR RATES... ESPECIALLY SINCE THE SNOW TO WATER RATIOS WILL BE HIGHER THANKS TO THE COLDER AIR. MAY HAVE TO WATCH FOR POTENTIAL FOR WINDS REACHING HIGH WIND WARNING CRITERIA TUE MORNING IN THE NORTH CENTRAL AS WELL...ESPEICALLY IF THE 18Z NAM PANS OUT. PCPN WILL DIMINISH WEST TO EAST ON TUE AS THE PHASED UPPER TROUGH MOVES AWAY FROM THE CWA...ALLOWING DRIER AIR AND SUBSIDENCE TO MOVE IN. QPF AMOUNTS FOLLOW A BLEND OF THE 12Z NAM...REGIONAL CANADIAN AND LOCAL WRF-ARW. NEW 18Z NAM IS EVEN HEAVIER WITH THE QPF...WHICH MIGHT NOT BE OUT OF THE QUESTION WITH THE SNOW REALLY INTENSIFYING OVER THE MINNEAPOLIS AREA. THE UPSLOPE IS VERY IMPRESSIVE OFF THE 18Z NAM AS WELL (TOTAL QPF OF 2.24 INCHES AT OUR OFFICE). TEMPS FOR TONIGHT AND TOMORROW LOOK REASONABLE AND VERY LITTLE MODIFICATION MADE. .LONG TERM... (TUE NIGHT THRU MON) QUIET NIGHT EXPECTED TUE NIGHT AS SFC HIGH PRES MOVES FROM THE UPPER MISSISSIPPI VALLEY INTO THE GREAT LAKES REGION. IT WILL NOT BE AN IDEAL RADIATIONAL COOLING SETUP WITH CENTER OF SFC HIGH PASSING THRU SRN WI. IN ADDITION...THERE IS SOME UNCERTAINTY ON THE CLOUD SITUATION AS STRONGER WAA PATTERN TO THE NW SHOULD SEND SOME CLOUDS SE INTO UPPER MI. NONETHELESS...FRESH SNOW COVER/LIGHT WINDS AND AT LEAST SOME TIME WITH LIMITED CLOUD COVER SUGGEST GOING BLO MOS GUIDANCE AS PREVIOUS FCST HAD INDICATED. SHOULD THE NIGHT END UP MOSTLY CLEAR...TEMPS MAY SLIP BLO ZERO IN THE TYPICAL COLD SPOTS. A COUPLE OF WEAK SHORTWAVES WILL BE TRACKING THRU THE UPPER GREAT LAKES REGION WED. SINCE BEST ISENTROPIC ASCENT SLIDES BY JUST N OF UPPER MI AND THERE WILL BE A DRY AIRMASS TO OVERCOME INITIALLY... OPTED TO MAINTAIN A DRY FCST WED WITH THE EXCEPTION OF NRN LAKE SUPERIOR. NEXT SHORTWAVE TROF SWINGS THRU THE UPPER LAKES ON THU. SINCE ANTECEDENT AIRMASS WON`T BE AS DRY AS WED...ISENTROPIC ASCENT MAY BE SUFFICIENT FOR SOME -SN WITH THIS SYSTEM LATE WED NIGHT THRU THU MORNING. HAVE THUS RETAINED SLIGHT CHC POPS FOR -SN AS SHORTWAVE PASSES. FRI THRU MON...ALTHOUGH THERE ARE SIGNIFICANT MODEL DIFFERENCES WITH THE PATTERN ACROSS THE CONUS...IT APPEARS AT THE MOMENT THAT THIS SHOULD BE A RELATIVELY QUIET PERIOD OF WEATHER ACROSS THE FCST AREA. THE ECMWF DEVELOPS MUCH MORE TROFFING OVER THE WRN CONUS OVER THE WEEKEND INTO EARLY NEXT WEEK THAN THE GFS...RESULTING IN SW FLOW TAKING SHAPE INTO THE GREAT LAKES. THE GFS HAS A W TO NW FLOW INTO THE GREAT LAKES AS POLAR VORTEX OVER HUDSON BAY MAINTAINS INFLUENCE OVER THE AREA. THE GLOBAL CANADIAN OFFERS A SOLUTION BTWN THE GFS AND ECMWF. GIVEN THE DIFFERENCES...IT`S USUALLY BEST TO MAKE MINIMAL CHANGES TO PREVIOUS FCST UNTIL BETTER MODEL AGREEMENT DEVELOPS. IN THIS CASE...THE PREVIOUS FCST LINES UP REASONABLY WELL WITH THE GFS...AND THE 12Z ECMWF HAS TRENDED SOMEWHAT TOWARD THE GFS SOLUTION. SO...WILL MAINTAIN LOW POPS OVER THE WEEKEND FOR THE POSSIBILITY OF A COLD FRONT SETTLING INTO THE UPPER LAKES EARLY SAT AND THEN THE POTENTIAL FOR ANOTHER FROPA SUN. AIRMASS SHOULD BE WARM ENOUGH TO FOR MIXED PTYPES (-SN/-RA) DURING THE AFTN HRS. EXPECT A DRY DAY MON. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT PREDOMINANT IFR/LIFR CONDITIONS TO PERSIST THRU SUNRISE WITH INCRSG NNE WINDS CAUSING NEAR BLIZZARD CONDITIONS AT SAW ON TUE MRNG AS LO PRES MOVES FM NR MKE TO SE ONTARIO THIS MRNG. CONDITIONS SHOULD IMPROVE RPDLY TO VFR BY LATE TUE MRNG AT CMX AND THEN IN THE AFTN AT SAW AS SFC LO PULLS TO THE NE AND DRIER AIR INVADES FM THE W. HI PRES PUSHING INTO THE UPR MIDWEST/WEAKENING PRES GRADIENT WL ALSO ALLOW WINDS TO DIMINISH QUICKLY BY LATE IN THE DAY. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRESSURE OVER IOWA WILL DEEPEN TONIGHT AS IT LIFTS TO NORTHERN LAKE HURON BY TUE MORNING. 35 KT GALE FORCE WINDS ARE EXPECTED TO DEVELOP ACROSS LAKE SUPERIOR THIS EVENING...THEN INTENSIFY TO 40 TO 45 KT AFTER MIDNIGHT. IT IS POSSIBLE FOR STORM FORCE WINDS TO OCCUR ON EASTERN LAKE SUPERIOR TOMORROW MORNING...BUT CONFIDENCE IS NOT HIGH ENOUGH YET TO ISSUE THE STORM WARNING. WINDS WILL COME DOWN FAIRLY QUICK TOMORROW AS THE LOW DEPARTS AND A HIGH PRESSURE RIDGE BUILDS IN. BEYOND TUE NIGHT...WINDS LOOK TO REMAIN BELOW 25 KT THROUGH THE REST OF THE FORECAST. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER STORM WARNING UNTIL 1 PM EDT /NOON CDT/ THIS AFTERNOON FOR MIZ002-009-013-014-084. WINTER STORM WARNING UNTIL 5 PM EDT THIS AFTERNOON FOR MIZ007- 085. SNOW AND BLOWING SNOW ADVISORY UNTIL 1 PM EDT THIS AFTERNOON FOR MIZ001-003. BLIZZARD WARNING UNTIL 5 PM EDT THIS AFTERNOON FOR MIZ006. WINTER STORM WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR MIZ004. BLIZZARD WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR MIZ005. WINTER STORM WARNING UNTIL 7 AM CDT THIS MORNING FOR MIZ010>012. LAKE SUPERIOR... GALE WARNING UNTIL 8 PM EDT THIS EVENING FOR LSZ265>267. GALE WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR LSZ244>249-264. GALE WARNING UNTIL 11 AM EDT /10 AM CDT/ THIS MORNING FOR LSZ240>243. GALE WARNING UNTIL 2 AM EDT EARLY THIS MORNING FOR LSZ162. GALE WARNING UNTIL 8 AM EDT THIS MORNING FOR LSZ263. GALE WARNING UNTIL 6 PM EDT THIS AFTERNOON FOR LSZ250-251. LAKE MICHIGAN... GALE WARNING FROM 8 AM THIS MORNING TO 3 PM EDT THIS AFTERNOON FOR LMZ221-248-250. && $$ UPDATE...KC SYNOPSIS/SHORT TERM...AJ LONG TERM...ROLFSON AVIATION...KC MARINE...AJ
AREA FORECAST DISCUSSION
NWS RALEIGH NC
322 AM EDT TUE APR 1 2008 .SYNOPSIS...BREEZY SOUTHERLY WINDS WILL SPREAD WARMER AIR OVER THE REGION TODAY. A COLD FRONT WILL APPROACH FROM THE WEST LATE TODAY AND CROSS THE AREA TONIGHT. ANOTHER COOL HIGH PRESSURE AREA WILL BUILD IN FROM THE NORTH ON WEDNESDAY. && .NEAR TERM /THROUGH TODAY/... AS OF 300 AM TUESDAY... A SPLIT FLOW REGIME OVER THE WESTERN U.S THAT CONVERGES OVER THE CENTRAL U.S. WILL MAINTAIN A UNSETTLED WEATHER PATTERN OVER CENTRAL NC THROUGH THE NEXT 3-5 DAYS. THIS MORNING...RESIDUAL PIEDMONT AIRMASS GRADUALLY ERODING OVER THE WESTERN AND SOUTHERN PIEDMONT WHILE WARMER AIR MASS HAS OVERSPREAD THE REMAINDER OF THE PIEDMONT INTO THE COASTAL PLAIN. FOG MAINLY CONFINED TO AREAS UNDER THE INFLUENCE OF THE PIEDMONT AIR MASS WHERE VISIBILITIES HOVERING BETWEEN 1/2-1SM. MAY EVENTUALLY NEED A SHORT FUSE DENSE FOG ADVISORY FOR THE WESTERN TIER OF COUNTIES. ISENTROPIC LIFT IN THE 290-295K LAYER STILL PRODUCING WIDESPREAD LIGHT RAIN/DRIZZLE ACROSS THE PIEDMONT. MODEL GUIDANCE INDICATE THAT THIS WILL GRADUALLY WEAKEN BETWEEN 06-12Z TUE WITH MAIN LIFT AT 12Z OVER THE COASTAL PLAIN. THUS WILL TAPER POPS AT 12Z FROM CHANCE WEST TO LIKELY EAST. THIS AFTERNOON...BREEZY S-SW LOW LEVEL FLOW WILL ADVECT MARGINALLY UNSTABLE AIRMASS INTO THE REGION. MID LEVEL LAPSE RATES PROGGED TO BE AROUND 6 DEG C AND LOW LEVEL WIND SHEAR PROFILE SUPPORTIVE OF ORGANIZED CONVECTION. WET BULB ZERO HEIGHTS IN THE FAVORED RANGE FOR LARGE HAIL. GFS SOUNDINGS MORE DIRER IN SEVERE POTENTIAL THAN NAM BUT GFS ALSO SUGGEST SURFACE DEWPOINTS IN THE MID 60S (CHANCES OF VERIFYING THIS SLIM). MAIN TRIGGER FOR SCATTERED TO NUMEROUS SHOWERS AND A FEW STORMS WILL BE A FAST MOVING MID LEVEL TROUGH SUPPORTED ALOFT BY AREA OF H3 DIFFLUENCE. DUE TO THE SOGGY AIRMASS IN PLACE...LIKELY POPS WARRANTED FOR THIS AFTERNOON..AND INTO THE EVENING IN THE EAST. WHILE WIDESPREAD SEVERE STORMS NOT EXPECTED...THERE DOES APPEAR TO BE ENOUGH INSTABILITY AND KINEMATICS TO SUPPORT ISOLATED SEVERE STORMS ACROSS THE REGION...ESPECIALLY IN THE SANDHILLS AND THE COASTAL PLAIN. WILL NEED TO MONITOR NEAR SURFACE DEWPOINTS. IF THESE START TO CREEP INTO THE MID 60S...THINGS COULD BECOME INTERESTING IN A HURRY. TEMPS TODAY STILL A BIT PROBLEMATIC IN THE NW PIEDMONT. WHILE PIEDMONT AIRMASS RATHER SHALLOW...IT MAY TAKE A WHILE LONGER THAN CURRENTLY FORECAST TO SCOUR OUT. MAX TEMPS IN THE UPPER 60S MAY BE A STRETCH IN THE TRIAD AND MAY ADJUST DOWN A CATEGORY BEFORE FORECAST ISSUANCE. OTHERWISE...BREEZY SLY FLOW WILL AID IN PUSHING TEMPS ELSEWHERE ABOVE THE 70 DEGREE MARK (A NICE CHANGE AFTER THE PAST FEW DAYS). && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... AS OF 320 AM TUESDAY... SURFACE COLD FRONT STILL ON TRACK TO CROSS THE REGION LATE TONIGHT THEN STALL NEAR OR JUST SOUTH OF THE REGION WEDNESDAY. COOL HIGH PRESSURE OVER THE GREAT LAKES WILL TRANSLATE EAST INTO THE NORTHERN MID ATLANTIC AND BUILD SOUTH INTO NC WED AND WED NIGHT. THIS SCENARIO WILL SUPPORT ANOTHER COLD AIR DAMMING SITUATION (BUT SHOULD NOT BE AS LONG IN DURATION AS RECENT EVENT). 925-850MB S-SW FLOW WILL INCREASE LATE WED NIGHT INTO THU...INCREASING ISENTROPIC LIFT FROM S-N ACROSS THE REGION. WILL BOOST POPS THU TO HIGH CHANCE (WILL PROBABLY NEED TO INCREASE TO LIKELY OR LOW CATEGORICAL IN LATER FORECAST ISSUANCES IF LATER MODEL GUIDANCE CONSISTENT). WITH OVERCAST SKIES AND POTENTIAL FOR MORE RAIN...COOL TEMPS ANTICIPATED FOR THU. WITH HYBRID DAMMING SET-UP...LOWERED MAX TEMPS A FEW DEGREES IN THE NW PIEDMONT AND MAY NEED ADJUSTMENTS REMAINDER OF THE PIEDMONT. MODELS CURRENTLY IN GENERAL AGREEMENT ERODING CAD AIRMASS THU NIGHT WITH MOIST WARM AIR MASS OVER THE REGION FRI INTO FRI NIGHT. EXPECT TO SEE AN INCREASE IN SHOWERS FRI NIGHT INTO EARLY SATURDAY AS NEXT COLD FRONT APPROACHES. TEMPS WILL BE ON A ROLLER COASTER RIDE THIS WEEK. AFTER HIGHS TODAY IN THE 60S/70S EXPECT A DOWNTURN WED INTO THU WITH MAX TEMPS WED NEAR 60 NORTH TO MID 60S SOUTH..AND UPPER 40S NW TO LOWER 60S SE THU. WARM SLY FLOW FRI WILL BOOST TEMPS BACK INTO THE 70S FRI. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 AM TUESDAY... THE LATEST 00Z/01 GFS IS BEGINNING TO TREND TOWARDS THE SLOWER DETERMINISTIC SOLUTION OF THE ECMWF...INDICATING COLD FRONT PASSAGE EXTENDING INTO THE AFTERNOON AND EVENING HOURS ON SATURDAY. THE SLOWER TIMING IS ALSO IN BETTER AGREEMENT WITH THE GFSENSEMBLE MEAN. AS A RESULT...HAVE RAISED POPS TO CHANCE DURING THE DAY ON SATURDAY...CONTINUING THE CHANCE OF SHOWERS AND THUNDERSTORMS...WITH MODELS SHOWING A MODERATELY AMPLIFIED TROUGH ALOFT...FAVORABLE RR JET DYNAMICS...AND STRONG DEEP (0 TO 6KM) LAYER SHEAR OF 45 TO 50KTS. CLOUDS AND MOISTURE EXIT THE AREA OVERNIGHT SATURDAY NIGHT AS HIGH PRESSURE BUILDS IN FROM THE WEST. UPPER FLOW REGIME LOOKS TO STAY FLAT AND PROGRESSIVE INTO EARLY NEXT WEEK. SUNDAY AND MONDAY WILL REMAIN DRY WITH SEASONABLE TEMPERATURES. HIGHS 65 TO 70. LOWS IN THE 40S. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 130 AM TUESDAY... CLASSICAL DIABATICALLY ENHANCED COLD AIR DAMMING EVENT AND ASSOC IFR/LIFR CONDITIONS CONTINUES ACROSS WESTERN PORTIONS OF THE FORECAST AREA. LATEST OBSERVATION FROM THE RDU INTERNATIONAL REPORTS 2M SURFACE WINDS HAVE SWITCHED AROUND TO SOUTHERLY...INDICATING WEDGE BOUNDARY(WARM FRONT)HAS JUST PUSHED WEST OF THE AREA. HARD TO DETERMINE IF THIS IS PERMANENT...OR JUST TEMPORARILY...AS BOUNDARY HAS BEEN MEANDERING WEST AND EAST OVER THE PAST EVENING. EXPECT TO SEE IMPROVED IMPROVED CIGS/VSBYS IN THE WARM SECTOR...EAST OF THE TRIANGLE...WITH VISIBILITIES RANGING FROM MVFR TO VFR AND CEILINGS RANGING FROM 200 TO 2000 FT...WITH LOWEST CONDITIONS EXPECTED RIGHT ALONG THE FRONT AT THE RDU. IN THE WESTERN PIEDMONT...WHERE WEDGE CONTINUES TO HANG TOUGH...LIFR TO IFR CEILINGS AND VISIBILITIES. ALSO...AREA AMDAR AIRCRAFT SOUNDINGS SHOW STRONG SOUTHERLY LLJ AND SHEAR OVER THE WEDGE REGIME...WITH 35 TO 40KTS AOA 1500FT...ATOP NEARLY CALM OR LIGHT NE WINDS. WILL INCLUDE NON CONVECTIVE LLWS FOR JUST KINT AND KGSO THROUGH 12Z. VISIBILITIES SHOULD REBOUND INTO THE VFR CATEGORY BY MIDDAY TUESDAY (FROM EAST TO WEST) AS THE AIR NEAR THE SURFACE BECOMES WELL MIXED (850 SWLY WINDS 45 TO 50 KTS) OUT AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. CEILINGS MAY BRIEFLY LIFT TO THE HIGH END OF MVFR OR LOW END OF VFR BY TUESDAY AFTERNOON. HEATING OF THE MOIST AND MARGINALLY UNSTABLE AIR MASS MAY LEAD TO THE DEVELOPMENT OF SCATTERED SHOWERS OR THUNDERSTORMS TUESDAY AFTERNOON...ESPECIALLY IN THE COASTAL PLAIN REGION. THESE SHOWERS/STORMS MAY PERSIST INTO TUESDAY NIGHT AS A COLD FRONT CROSSES THE REGION. SOUTHWEST WINDS WILL LIKELY BECOME BREEZY TUESDAY AFTERNOON AHEAD OF THE FRONT...BECOMING SUSTAINED AT 10-15 KNOTS WITH GUSTS UP TO 25 KNOTS. MAY SEE ANOTHER COLD AIR DAMMING EVENT WITH ASSOCIATED LOW CEILINGS/VISIBILITIES WED NIGHT THROUGH THUR NIGHT AS ANOTHER STRONG ARE OF HIGH PRESSURE BUILDS ACROSS THE NORTHERN MID ATLANTIC REGION. ANOTHER COLD FRONT IS EXPECTED TO APPROACH FROM THE WEST FRIDAY AFTERNOON...AND CROSS THE AREA EARLY SATURDAY. THIS COULD RESULT IN MORE UNSETTLED WEATHER AT THAT TIME. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...CBL AVIATION...CBL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 AM EDT TUE APR 1 2008 .SYNOPSIS...BREEZY SOUTHERLY WINDS WILL SPREAD WARMER AIR OVER THE REGION TODAY. A COLD FRONT WILL APPROACH FROM THE WEST LATE TODAY AND CROSS THE AREA TONIGHT. ANOTHER COOL HIGH PRESSURE AREA WILL BUILD IN FROM THE NORTH ON WEDNESDAY. && .NEAR TERM /THROUGH TODAY/... AS OF 300 AM TUESDAY... A SPLIT FLOW REGIME OVER THE WESTERN U.S THAT CONVERGES OVER THE CENTRAL U.S. WILL MAINTAIN A UNSETTLED WEATHER PATTERN OVER CENTRAL NC THROUGH THE NEXT 3-5 DAYS. THIS MORNING...RESIDUAL PIEDMONT AIRMASS GRADUALLY ERODING OVER THE WESTERN AND SOUTHERN PIEDMONT WHILE WARMER AIR MASS HAS OVERSPREAD THE REMAINDER OF THE PIEDMONT INTO THE COASTAL PLAIN. FOG MAINLY CONFINED TO AREAS UNDER THE INFLUENCE OF THE PIEDMONT AIR MASS WHERE VISIBILITIES HOVERING BETWEEN 1/2-1SM. MAY EVENTUALLY NEED A SHORT FUSE DENSE FOG ADVISORY FOR THE WESTERN TIER OF COUNTIES. ISENTROPIC LIFT IN THE 290-295K LAYER STILL PRODUCING WIDESPREAD LIGHT RAIN/DRIZZLE ACROSS THE PIEDMONT. MODEL GUIDANCE INDICATE THAT THIS WILL GRADUALLY WEAKEN BETWEEN 06-12Z TUE WITH MAIN LIFT AT 12Z OVER THE COASTAL PLAIN. THUS WILL TAPER POPS AT 12Z FROM CHANCE WEST TO LIKELY EAST. THIS AFTERNOON...BREEZY S-SW LOW LEVEL FLOW WILL ADVECT MARGINALLY UNSTABLE AIRMASS INTO THE REGION. MID LEVEL LAPSE RATES PROGGED TO BE AROUND 6 DEG C AND LOW LEVEL WIND SHEAR PROFILE SUPPORTIVE OF ORGANIZED CONVECTION. WET BULB ZERO HEIGHTS IN THE FAVORED RANGE FOR LARGE HAIL. GFS SOUNDINGS MORE DIRER IN SEVERE POTENTIAL THAN NAM BUT GFS ALSO SUGGEST SURFACE DEWPOINTS IN THE MID 60S (CHANCES OF VERIFYING THIS SLIM). MAIN TRIGGER FOR SCATTERED TO NUMEROUS SHOWERS AND A FEW STORMS WILL BE A FAST MOVING MID LEVEL TROUGH SUPPORTED ALOFT BY AREA OF H3 DIFFLUENCE. DUE TO THE SOGGY AIRMASS IN PLACE...LIKELY POPS WARRANTED FOR THIS AFTERNOON..AND INTO THE EVENING IN THE EAST. WHILE WIDESPREAD SEVERE STORMS NOT EXPECTED...THERE DOES APPEAR TO BE ENOUGH INSTABILITY AND KINEMATICS TO SUPPORT ISOLATED SEVERE STORMS ACROSS THE REGION...ESPECIALLY IN THE SANDHILLS AND THE COASTAL PLAIN. WILL NEED TO MONITOR NEAR SURFACE DEWPOINTS. IF THESE START TO CREEP INTO THE MID 60S...THINGS COULD BECOME INTERESTING IN A HURRY. TEMPS TODAY STILL A BIT PROBLEMATIC IN THE NW PIEDMONT. WHILE PIEDMONT AIRMASS RATHER SHALLOW...IT MAY TAKE A WHILE LONGER THAN CURRENTLY FORECAST TO SCOUR OUT. MAX TEMPS IN THE UPPER 60S MAY BE A STRETCH IN THE TRIAD AND MAY ADJUST DOWN A CATEGORY BEFORE FORECAST ISSUANCE. OTHERWISE...BREEZY SLY FLOW WILL AID IN PUSHING TEMPS ELSEWHERE ABOVE THE 70 DEGREE MARK (A NICE CHANGE AFTER THE PAST FEW DAYS). && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... AS OF 320 PM MONDAY... WEAK REMNANTS OF THE WEDGE REGIME MAY STILL BE HOLDING ON IN THE WINSTON-SALEM AREA AFTER SUNRISE TUESDAY... HOWEVER THIS SHOULD QUICKLY ERODE AND THE REST OF THE AREA WILL BE FIRMLY IN THE WARM SECTOR WITH STOUT SW FLOW AHEAD OF THE INCOMING COLD FRONT. FORCING FOR ASCENT SHOULD BEGIN TO IMPROVE TUESDAY MORNING AS A WEAK MID LEVEL PERTURBATION APPROACHES FROM THE WEST... BUT IN GENERAL THE LIFT MECHANISMS SHOULD BE DECREASING AS ISENTROPIC UPGLIDE WANES AND THE UPPER JET CORE HOLDS WELL TO OUR NORTH. FORECAST INSTABILITY IS MARGINAL WITH MODEL CONSENSUS MUCAPE VALUES ONLY AROUND 400-800 J/KG IN THE SOUTHEAST CWA... WHERE THE SREF PROBABILITY OF > 1000 J/KG OF CAPE IS LESS THAN 20%. WIND FIELDS ARE DECENT THOUGH WITH 850 MB WINDS SURPASSING 40 KTS. HAVE KEPT A MENTION OF THUNDER... MAINLY IN THE SOUTHEAST HALF OF THE AREA... BUT THE OVERALL RISK OF MORE THAN A COUPLE OF STRONG STORMS IS SMALL AND THREATS SHOULD BE LIMITED TO STRONG GUSTS. WILL HAVE HIGHS 69-75... REASONABLE CONSIDERING THICKNESSES ARE PROJECTED TO BE AROUND 30 M ABOVE NORMAL. THE COLD FRONT IS EXPECTED TO DROP SOUTHEASTWARD INTO THE NW PIEDMONT TUESDAY EVENING AND BE ORIENTED ACROSS THE SOUTHEAST CWA WEDNESDAY MORNING. HAVE KEPT CHANCE POPS FOR SHOWERS THROUGH TUESDAY NIGHT INTO WEDNESDAY MORNING... WITH FORCING LIMITED TO FRONTAL MASS CONVERGENCE. A CHILLY 1035 MB HIGH WILL PUSH IN FROM THE GREAT LAKES IN WHAT LOOKS TO BE ANOTHER DEVELOPING COLD AIR DAMMING EVENT. THIS HIGH SHOULD BE SOMEWHAT MODIFIED AS IT ARRIVES BUT WITH VERY COLD TEMPERATURES AND DEWPOINTS CURRENTLY BENEATH IT... IT SHOULD PACK ENOUGH OF A PUNCH OF COLD AIR TO HOLD HIGHS WEDNESDAY IN THE 60-65 DEGREE RANGE... AFTER LOWS OF 50-58. -GIH && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 AM MONDAY... THE LATEST 00Z/01 GFS IS BEGINNING TO TREND TOWARDS THE SLOWER DETERMINISTIC SOLUTION OF THE ECMWF...INDICATING COLD FRONT PASSAGE EXTENDING INTO THE AFTERNOON AND EVENING HOURS ON SATURDAY. THE SLOWER TIMING IS ALSO IN BETTER AGREEMENT WITH THE GFSENSEMBLE MEAN. AS A RESULT...HAVE RAISED POPS TO CHANCE DURING THE DAY ON SATURDAY...CONTINUING THE CHANCE OF SHOWERS AND THUNDERSTORMS...WITH MODELS SHOWING A MODERATELY AMPLIFIED TROUGH ALOFT...FAVORABLE RR JET DYNAMICS...AND STRONG DEEP (0 TO 6KM) LAYER SHEAR OF 45 TO 50KTS. CLOUDS AND MOISTURE EXIT THE AREA OVERNIGHT SATURDAY NIGHT AS HIGH PRESSURE BUILDS IN FROM THE WEST. UPPER FLOW REGIME LOOKS TO STAY FLAT AND PROGRESSIVE INTO EARLY NEXT WEEK. SUNDAY AND MONDAY WILL REMAIN DRY WITH SEASONABLE TEMPERATURES. HIGHS 65 TO 70. LOWS IN THE 40S. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 130 AM TUESDAY... CLASSICAL DIABATICALLY ENHANCED COLD AIR DAMMING EVENT AND ASSOC IFR/LIFR CONDITIONS CONTINUES ACROSS WESTERN PORTIONS OF THE FORECAST AREA. LATEST OBSERVATION FROM THE RDU INTERNATIONAL REPORTS 2M SURFACE WINDS HAVE SWITCHED AROUND TO SOUTHERLY...INDICATING WEDGE BOUNDARY(WARM FRONT)HAS JUST PUSHED WEST OF THE AREA. HARD TO DETERMINE IF THIS IS PERMANENT...OR JUST TEMPORARILY...AS BOUNDARY HAS BEEN MEANDERING WEST AND EAST OVER THE PAST EVENING. EXPECT TO SEE IMPROVED IMPROVED CIGS/VSBYS IN THE WARM SECTOR...EAST OF THE TRIANGLE...WITH VISIBILITIES RANGING FROM MVFR TO VFR AND CEILINGS RANGING FROM 200 TO 2000 FT...WITH LOWEST CONDITIONS EXPECTED RIGHT ALONG THE FRONT AT THE RDU. IN THE WESTERN PIEDMONT...WHERE WEDGE CONTINUES TO HANG TOUGH...LIFR TO IFR CEILIINGS AND VISIBILITIES. ALSO...AREA AMDAR AIRCRAFT SOUNDINGS SHOW STRONG SOUTHERLY LLJ AND SHEAR OVER THE WEDGE REGIME...WITH 35 TO 40KTS AOA 1500FT...ATOP NEARLY CALM OR LIGHT NE WINDS. WILL INCLUDE NON CONVECTIVE LLWS FOR JUST KINT AND KGSO THROUGH 12Z. VISIBILITIES SHOULD REBOUND INTO THE VFR CATEGORY BY MIDDAY TUESDAY (FROM EAST TO WEST) AS THE AIR NEAR THE SURFACE BECOMES WELL MIXED (850 SWLY WINDS 45 TO 50 KTS) OUT AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. CEILINGS MAY BRIEFLY LIFT TO THE HIGH END OF MVFR OR LOW END OF VFR BY TUESDAY AFTERNOON. HEATING OF THE MOIST AND MARGINALLY UNSTABLE AIR MASS MAY LEAD TO THE DEVELOPMENT OF SCATTERED SHOWERS OR THUNDERSTORMS TUESDAY AFTERNOON...ESPECIALLY IN THE COASTAL PLAIN REGION. THESE SHOWERS/STORMS MAY PERSIST INTO TUESDAY NIGHT AS A COLD FRONT CROSSES THE REGION. SOUTHWEST WINDS WILL LIKELY BECOME BREEZY TUESDAY AFTERNOON AHEAD OF THE FRONT...BECOMING SUSTAINED AT 10-15 KNOTS WITH GUSTS UP TO 25 KNOTS. MAY SEE ANOTHER COLD AIR DAMMING EVENT WITH ASSOCIATED LOW CEILINGS/VISIBILITIES WED NIGHT THROUGH THUR NIGHT AS ANOTHER STRONG ARE OF HIGH PRESSURE BUILDS ACROSS THE NORTHERN MID ATLANTIC REGION. ANOTHER COLD FRONT IS EXPECTED TO APPROACH FROM THE WEST FRIDAY AFTERNOON...AND CROSS THE AREA EARLY SATURDAY. THIS COULD RESULT IN MORE UNSETTLED WEATHER AT THAT TIME. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS SHORT TERM...WSS LONG TERM...CBL AVIATION...CBL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
130 AM EDT TUE APR 01 2008 .SYNOPSIS... A STATIONARY FRONT WILL LINGER OVER CENTRAL NC TONIGHT THEN MOVE NORTHWEST AS A WARM FRONT TUE. A COLD FRONT WILL APPROACH FROM THE WEST LATE TUESDAY AND CROSS THE AREA TUESDAY NIGHT. ANOTHER COOL HIGH PRESSURE AREA WILL BUILD IN FROM THE NORTH ON WEDNESDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... AS OF 720 PM MONDAY... THE NEARLY STATIONARY FRONT IS EXPECTED TO REMAIN OVER THE EASTERN PIEDMONT AND SANDHILLS OVERNIGHT WITH CONVERGENCE OF WARM HUMID AIR ON SOUTHERLY FLOW IN VICINITY OF THE FRONT NEAR THE SURFACE. THIS WILL MAINTAIN A STEADY FEED OF RAIN AREAS FROM COASTAL SC INTO THE RAH CWA DURING THE NIGHT WITH THE GREATEST AMOUNTS ALONG THE U.S. ROUTE ONE CORRIDOR. THE SATURATED LOW LEVEL AIR AND WEAK SURFACE FLOW IN THE COOL POOL WEST OF THE FRONT SHOULD LEAD TO WIDESPREAD FOG...POSSIBLY DENSE TOWARD MORNING. TEMPERATURES WILL SHOW ONLY MINOR FALLS EAST AND STEADY TO SLIGHTLY RISING OVERNIGHT WEST. -RFG && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/... AS OF 320 PM MONDAY... WEAK REMNANTS OF THE WEDGE REGIME MAY STILL BE HOLDING ON IN THE WINSTON-SALEM AREA AFTER SUNRISE TUESDAY... HOWEVER THIS SHOULD QUICKLY ERODE AND THE REST OF THE AREA WILL BE FIRMLY IN THE WARM SECTOR WITH STOUT SW FLOW AHEAD OF THE INCOMING COLD FRONT. FORCING FOR ASCENT SHOULD BEGIN TO IMPROVE TUESDAY MORNING AS A WEAK MID LEVEL PERTURBATION APPROACHES FROM THE WEST... BUT IN GENERAL THE LIFT MECHANISMS SHOULD BE DECREASING AS ISENTROPIC UPGLIDE WANES AND THE UPPER JET CORE HOLDS WELL TO OUR NORTH. FORECAST INSTABILITY IS MARGINAL WITH MODEL CONSENSUS MUCAPE VALUES ONLY AROUND 400-800 J/KG IN THE SOUTHEAST CWA... WHERE THE SREF PROBABILITY OF > 1000 J/KG OF CAPE IS LESS THAN 20%. WIND FIELDS ARE DECENT THOUGH WITH 850 MB WINDS SURPASSING 40 KTS. HAVE KEPT A MENTION OF THUNDER... MAINLY IN THE SOUTHEAST HALF OF THE AREA... BUT THE OVERALL RISK OF MORE THAN A COUPLE OF STRONG STORMS IS SMALL AND THREATS SHOULD BE LIMITED TO STRONG GUSTS. WILL HAVE HIGHS 69-75... REASONABLE CONSIDERING THICKNESSES ARE PROJECTED TO BE AROUND 30 M ABOVE NORMAL. THE COLD FRONT IS EXPECTED TO DROP SOUTHEASTWARD INTO THE NW PIEDMONT TUESDAY EVENING AND BE ORIENTED ACROSS THE SOUTHEAST CWA WEDNESDAY MORNING. HAVE KEPT CHANCE POPS FOR SHOWERS THROUGH TUESDAY NIGHT INTO WEDNESDAY MORNING... WITH FORCING LIMITED TO FRONTAL MASS CONVERGENCE. A CHILLY 1035 MB HIGH WILL PUSH IN FROM THE GREAT LAKES IN WHAT LOOKS TO BE ANOTHER DEVELOPING COLD AIR DAMMING EVENT. THIS HIGH SHOULD BE SOMEWHAT MODIFIED AS IT ARRIVES BUT WITH VERY COLD TEMPERATURES AND DEWPOINTS CURRENTLY BENEATH IT... IT SHOULD PACK ENOUGH OF A PUNCH OF COLD AIR TO HOLD HIGHS WEDNESDAY IN THE 60-65 DEGREE RANGE... AFTER LOWS OF 50-58. -GIH && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... AS OF 145 PM MONDAY... FORECAST CONFIDENCE CONTINUES TO INCREASE FOR THE THU-THU NIGHT PERIOD. A FRESH... INITIALLY DRY CLASSICAL COLD AIR DAMMING HIGH (1030 TO 1035 MB) WILL BUILD EASTWARD FROM THE EASTERN GREAT LAKES REGION WEDNESDAY EVENING REGION TO THE JERSEY COAST BY THURSDAY MORNING. FORECAST LOW LEVEL THICKNESSES DIP B/W 1320 AND 1340 METERS... WITH DRY SFC DEWPOINTS IN THE 25 TO 35 DEGREE RANGE BY 12Z THU. THIS WILL SET THE STAGE FOR ALMOST A MIRROR IMAGE OF TODAY... WITH STRONG ISENTROPIC LIFT (30 KT CROSS CONTOUR/TIGHT GRADIENT FLOW) IN THE 290-300 K LAYER AND ATOP THE SFC WEDGE... AND RESULT IN ANOTHER CLASSICAL DIABATICALLY ENHANCED CAD EVENT THURSDAY AND THURSDAY NIGHT. WILL ACCORDINGLY SHOW AN INCREASING CHANCE OF RAIN BEGINNING THURSDAY MORNING IN THE SOUTH AND EARLY AFTERNOON NORTH... CONTINUING THROUGH THE NIGHTTIME HOURS. HIGHS WILL STRUGGLE TO REACH 50 IN THE TRIAD... WITH LOWER 60S IN THE COASTAL PLAIN... EAST OF THE RETREATING CAD FRONT FROM THE COAST. FRI-FRI NIGHT...THE MEDIUM RANGE GUIDANCE IS STILL IN DISAGREEMENT REGARDING THE EVOLUTION OF THE UPPER TROUGH CURRENTLY NEAR 140W/35N IN THE EASTERN PACIFIC. THE LAST FEW CYCLES OF GFS QUICKLY ADVANCE THIS FEATURE ACROSS THE CONUS AND PLACES AN ATTENDANT SFC WAVE IN THE OHIO VALLEY AT 12Z FRI. THE LAST 2 ECMWF CYCLES... ON THE OTHER HAND... ARE MUCH SLOWER WITH THE PROGRESSION OF THE UPPER TROUGH AND ACCORDINGLY HOLD THE SFC WAVE OVER THE SOUTHERN PLAINS AT THAT TIME. GIVEN THE CONTINUED UNCERTAINTY... WILL CLOSELY FOLLOW HPC WITH SOMEWHAT OF A BLEND OF THESE TWO SOLUTIONS... WHICH WOULD RESULT IN THE SFC LOW ADVANCING THROUGH THE TN VALLEY FRIDAY... WITH AN ATTENDANT COLD FRONTAL PASSAGE THROUGH NC SATURDAY MORNING. THE PASSAGE OF THE LOW THROUGH THE TN VALLEY FRIDAY IS A CAD EROSION SCENARIO WHICH SHOULD LEAD TO THE DEMISE OF THE RESIDUAL CAD WEDGE FROM THURSDAY NIGHT. INCREASING SOUTHWESTERLY FLOW AHEAD OF THE LOW SHOULD BOOST HIGHS INTO THE 70S ACROSS THE FORECAST AREA... PERHAPS NEARING 80 IN THE COASTAL PLAIN. THERMAL PROFILES BECOME SUPPORTIVE OF DEEP CONVECTION FRIDAY AFTERNOON... BUT A LACK OF ANY DISCERNIBLE TRIGGER MAY PRECLUDE DEVELOPMENT UNTIL THE FRONT DRAWS NEARER LATER FRIDAY EVENING INTO THE OVERNIGHT. FORECAST CONFIDENCE FURTHER DECREASES THROUGH THE WEEKEND...AS THE GFS STALLS THE SFC FRONT JUST TO OUR SOUTH... WHERE IT INDUCES CYCLOGENESIS THAT RUNS UP THE COAST SATURDAY AND SATURDAY NIGHT. THIS IS A RESULT OF ANOTHER PROGRESSIVE TROUGH ALOFT WHOSE EVOLUTION THE MODELS DO NOT AGREE ON. WILL ACCORDINGLY STICK NEAR CLIMO IN THE SATURDAY THROUGH MONDAY TIME FRAME... AND MAINTAIN SILENT CHANCE POP. -MWS && .AVIATION /00Z MONDAY THROUGH SATURDAY/... AS OF 130 AM TUESDAY... CLASSICAL DIABATICALLY ENHANCED COLD AIR DAMMING EVENT AND ASSOC IFR/LIFR CONDITIONS CONTINUES ACROSS WESTERN PORTIONS OF THE FORECAST AREA. LATEST OBSERVATION FROM THE RDU INTERNATIONAL REPORTS 2M SURFACE WINDS HAVE SWITCHED AROUND TO SOUTHERLY...INDICATING WEDGE BOUNDARY(WARM FRONT)HAS JUST PUSHED WEST OF THE AREA. HARD TO DETERMINE IF THIS IS PERMANENT...OR JUST TEMPORARILY...AS BOUNDARY HAS BEEN MEANDERING WEST AND EAST OVER THE PAST EVENING. EXPECT TO SEE IMPROVED IMPROVED CIGS/VSBYS IN THE WARM SECTOR...EAST OF THE TRIANGLE...WITH VISIBILITIES RANGING FROM MVFR TO VFR AND CEILINGS RANGING FROM 200 TO 2000 FT...WITH LOWEST CONDITIONS EXPECTED RIGHT ALONG THE FRONT AT THE RDU. IN THE WESTERN PIEDMONT...WHERE WEDGE CONTINUES TO HANG TOUGH...LIFR TO IFR CEILIINGS AND VISIBILITIES. ALSO...AREA AMDAR AIRCRAFT SOUNDINGS SHOW STRONG SOUTHERLY LLJ AND SHEAR OVER THE WEDGE REGIME...WITH 35 TO 40KTS AOA 1500FT...ATOP NEARLY CALM OR LIGHT NE WINDS. WILL INCLUDE NON CONVECTIVE LLWS FOR JUST KINT AND KGSO THROUGH 12Z. VISIBILITIES SHOULD REBOUND INTO THE VFR CATEGORY BY MIDDAY TUESDAY (FROM EAST TO WEST) AS THE AIR NEAR THE SURFACE BECOMES WELL MIXED (850 SWLY WINDS 45 TO 50 KTS) OUT AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. CEILINGS MAY BRIEFLY LIFT TO THE HIGH END OF MVFR OR LOW END OF VFR BY TUESDAY AFTERNOON. HEATING OF THE MOIST AND MARGINALLY UNSTABLE AIR MASS MAY LEAD TO THE DEVELOPMENT OF SCATTERED SHOWERS OR THUNDERSTORMS TUESDAY AFTERNOON...ESPECIALLY IN THE COASTAL PLAIN REGION. THESE SHOWERS/STORMS MAY PERSIST INTO TUESDAY NIGHT AS A COLD FRONT CROSSES THE REGION. SOUTHWEST WINDS WILL LIKELY BECOME BREEZY TUESDAY AFTERNOON AHEAD OF THE FRONT...BECOMING SUSTAINED AT 10-15 KNOTS WITH GUSTS UP TO 25 KNOTS. MAY SEE ANOTHER COLD AIR DAMMING EVENT WITH ASSOCIATED LOW CEILINGS/VISIBILITIES WED NIGHT THROUGH THUR NIGHT AS ANOTHER STRONG ARE OF HIGH PRESSURE BUILDS ACROSS THE NORTHERN MID ATLANTIC REGION. ANOTHER COLD FRONT IS EXPECTED TO APPROACH FROM THE WEST FRIDAY AFTERNOON...AND CROSS THE AREA EARLY SATURDAY. THIS COULD RESULT IN MORE UNSETTLED WEATHER AT THAT TIME. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RFG NEAR TERM...RFG SHORT TERM...HARTFIELD LONG TERM...MWS AVIATION...CBL/VINCENT
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
348 AM CDT TUE APR 1 2008 FORECAST FOCUS ON ENDING PRECIPITATION THIS MORNING...WINDS TODAY...AND PRECIPITATION CHANCES THURSDAY THROUGH FRIDAY. LATEST WATER VAPOR IMAGERY INDICATED A SHORTWAVE TROUGH EXTENDING FROM NORTHEAST MINNESOTA SOUTHWEST INTO NORTHEAST NEBRASKA. VORTICITY MAXIMUM WITHIN THIS TROUGH WAS DRIVING CURRENT SNOW ACTIVITY OVER SOUTHERN MINNESOTA INTO CENTRAL WISCONSIN. AT THE SURFACE...LOW PRESSURE MOVING INTO NORTHERN LOWER MICHIGAN PULLED ITS COLD FRONT THROUGH SOUTHERN WISCONSIN. TEMPERATURES QUICKLY FELL INTO THE 30S BEHIND THE FRONT. .SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT... FIRST ISSUE IS TIMING OUT LINGERING SNOW SHOWERS THIS MORNING. AREA FORECAST SOUNDINGS SHOWED MOIST LOW LEVEL LAYER GRADUALLY RISING DURING THE MORNING HOURS...WITH RELATIVELY STEEP LOW LEVEL LAPSE RATES. LOCAL HIGH RESOLUTION 4KM MODELS KEPT MOST OF THE SNOW JUST NORTH OF THE FORECAST AREA. HOWEVER...GIVEN CURRENT SOUTHEAST MOVEMENT OF SNOW SHOWERS...COULD SEE SOME ACTIVITY MAKE IT INTO THE FORECAST AREA BEFORE SHORTWAVE TROUGH MOVES THROUGH THE REGION. WILL GO WITH SCATTERED SNOW SHOWER OR FLURRY WORDING IN NORTHEAST 2/3 OF FORECAST AREA. ANY SNOW ACCUMULATIONS WOULD BE LIGHT. NEXT ISSUE IS WINDY CONDITIONS FOR TODAY. STRONG COLD AIR ADVECTION CONTINUES TODAY...WITH 1000/500MB THICKNESSES DROPPING FROM THE 530S DKM RANGE AT 12Z TUESDAY TO THE LOWER 520S DKM RANGE BY 00Z WEDNESDAY. SURFACE PRESSURE GRADIENT STRONGEST THIS MORNING...BEFORE GRADUALLY EASING BY EVENING. AREA FORECAST SOUNDINGS SHOWED GOOD MIXING POTENTIAL UP TO 6000 FEET. WIND GUSTS IN THE 25 TO 35 KNOT RANGE IN THE MIXING LAYER ARE POSSIBLE. MAY SEE AN ISOLATED GUST OR SUSTAINED WIND TO WIND ADVISORY CRITERIA...BUT DO NOT EXPECT WIDESPREAD ACTIVITY. SO...WILL HOLD OFF ON A WIND ADVISORY AND JUST MENTION BRISK/WINDY WORDING IN FORECAST. HIGH PRESSURE MOVING ACROSS THE REGION SHOULD BRING QUIET WEATHER TONIGHT THROUGH WEDNESDAY NIGHT. .LONG TERM...THURSDAY THROUGH MONDAY... MODELS WERE KEEPING MOST OF THE PRECIPITATION ASSOCIATED WITH THE NEXT LOW PRESSURE SYSTEM SOUTH OF WISCONSIN FOR THURSDAY THROUGH FRIDAY. GFS ENSEMBLES FOLLOW THIS TREND WITH THEIR MEAN QPF FIELDS...WHILE THE ECMWF AND GFS HAVE VERY LIGHT QPF UP TO THE WISCONSIN AND ILLINOIS BORDER. HPC HAD BELOW AVERAGE CONFIDENCE IN THIS PERIOD WITH THE MEDIUM RANGE MODELS. WILL JUST MENTION A SLIGHT CHANCE FOR THURSDAY AND THURSDAY NIGHT IN SOUTHERN PORTIONS OF THE AREA. AFTER THAT...MODELS DIVERGE ON SYSTEM FOR THE WEEKEND. WILL LEAVE THIS PERIOD AS IS FOR NOW. && .AVIATION...EXPECT PATCHY DRIZZLE TO DIMINISH/END FOR A TIME BEFORE SCATTERED SNOW SHOWERS/FLURRIES SWEEPS THROUGH THIS MORNING IN RESPONSE TO PASSING MID LEVEL SHORT WAVE TROUGH. IFR CIGS SHOULD IMPROVE TO MVFR THIS MRNG AND VFR THIS AFTERNOON AS SUBSIDENCE DRYING MIXES WITH IN FROM THE NORTHWEST. WIDESPREAD CLEARING AFT 22Z. && .MARINE...LATEST TAMDAR SOUNDINGS OVER CENTRAL WI VERIFYING STRONGER LOW LEVEL WINDS ASSOCIATED WITH NAM. HENCE WILL FOLLOW NAM GUIDANCE OVER THE NEARSHORE WHICH SHOWS STEEP LAPSE RATES NEAR DRY ADIABATIC...DEVELOPING THIS MORNING. STEEP LAPSE RATES EXPECTED TO REACH 870MB WHICH WILL ALLOW WIND GUSTS TO 35KTS REACH LAKE SURFACE. GUST TO 40KTS OVER SOUTHERN PORTION OF GREEN BAY EARLIER. HENCE WL CONVERT SMALL CRAFT TO GALE WARNING AND RUN IT INTO THE EARLY AFTN. CAN THEN DOWNGRADE TO SMALL CRAFT INTO EARLY EVE. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...GALE WARNING UNTIL 4 PM CDT THIS AFTERNOON FOR LMZ643>646. && $$ SHORT/LONG TERM...08/WOOD AVIATION/MARINE...11/MBK
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1131 AM EDT TUE APR 1 2008 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL TRACK WELL TO OUR NORTH LATER THIS AFTERNOON AND TONIGHT, PULLING A COLD FRONT ACROSS OUR AREA THIS EVENING. HIGH PRESSURE WILL THEN BUILD OVER THE REGION ON WEDNESDAY AND MOVE OFFSHORE LATER THURSDAY. AN AREA OF LOW PRESSURE WILL THEN APPROACH FROM THE SOUTHWEST ON FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... OUR ENTIRE CWA REMAINS IN THE WARM SECTOR AS SOUTHERLY SURFACE WINDS HAVE TURNED GUSTY AT TIMES. A SURFACE ANALYSIS PLACES A STRENGTHENING LOW PRESSURE SYSTEM NORTH OF LAKE HURON WITH A TRAILING COLD FRONT SOUTHWARD INTO THE OHIO VALLEY. THIS FRONT WILL CONTINUE TO MOVE EASTWARD THROUGH THE AFTERNOON EVENTUALLY ARRIVING INTO OUR AREA. EMBEDDED WEAK AND SUBTLE SHORT WAVES HAVE GENERATED ROUNDS OF SHOWERS SO FAR. THE MAIN BATCH OF SHOWERS CONTINUES TO MOVE ACROSS EASTERN NEW JERSEY AND WILL EXIT THE AREA DURING THE EARLY AFTERNOON. MEANWHILE, SOME ADDITIONAL SHOWER DEVELOPMENT HAS POPPED UP ACROSS EASTERN PENNSYLVANIA. AS A RESULT, WE WILL RUN WITH HIGH CHC POPS TO INDICATE A MORE SCATTERED COVERAGE TO THE SHOWERS. THE VISIBLE SATELLITE IMAGERY SHOWS CLOUDS THINNING OUT SOME ACROSS NORTHERN VIRGINIA TO WESTERN MARYLAND. THIS IS TRACKING EASTWARD, HOWEVER THERE REMAINS AN ABUNDANCE OF MOISTURE ACROSS OUR AREA. THERE STILL CAN BE SOME BREAKS IN THE CLOUDS ESPECIALLY ACROSS SOUTHEASTERN PENNSYLVANIA ON SOUTHWARD, HOWEVER CONFIDENCE IS NOT HIGH REGARDING THIS. IF MORE BREAKS OCCUR, THEN TEMPERATURES WILL LIKELY SPIKE UP MORE THAN CURRENTLY THINKING. WE EDGED THE HIGH TEMPERATURES UP ACROSS MOST OF THE AREA JUST A BIT BASED ON TRENDS AND THE POTENTIAL FOR A FEW BREAKS IN THE CLOUDINESS. THE IMMEDIATE COAST IS A BIT TRICKY AS SURFACE WINDS ARE SOUTHERLY WITH THE TRAJECTORY OFF THE WATER FOR MOST OF COASTAL LOCALES. THE SURFACE WINDS MAY VEER A BIT MORE TO THE SOUTHWEST, HOWEVER MANY COASTAL LOCATIONS ARE RIGHT AROUND 50 DEGREES ATTM. THEREFORE WE OPTED TO LOWER THE HIGHS THERE SOME. SOME AIRCRAFT SOUNDINGS FROM PHILADELPHIA INTERNATIONAL ALONG WITH NEARBY 12Z RAOBS INDICATE SOME 50 KNOT WINDS AROUND 2500 FEET. THIS LOW-LEVEL JET IS FORECAST TO GRADUALLY SLIDE EASTWARD THROUGH THE AFTERNOON HOWEVER STILL A DECENT WIND FIELD IS PRESENT. WHILE SURFACE BASED INSTABILITY IS NOT EXISTENT THUS FAR, FORECAST SOUNDINGS DO INDICATE SOME WEAK INSTABILITY THROUGH THE AFTERNOON. THIS SETUP IS BASICALLY OF LOW CAPE /ON THE BASIS OF NOT MUCH BREAKS IN THE CLOUDS/ WITH A STRONG WIND FIELD. AS A RESULT, WE EXPANDED THE MENTION OF A CHC OF SOME THUNDERSTORMS ACROSS THE ENTIRE AREA, WHICH MATCHES UP WITH SPC`S DAY ONE OUTLOOK. THUNDER MAY NOT OCCUR UNTIL LATER THIS AFTERNOON OR EARLY THIS EVENING AS THE FRONTAL SURFACE NEARS AND MOVES THROUGH. THERE IS THE CHC OF SOME LOW-TOPPED CONVECTIVE ELEMENTS THAT MAY CONTAIN LITTLE OR NO LIGHTNING. WITH THE STRONGER WINDS PRESENT, SOME OF THOSE CELLS COULD TRANSPORT THAT WIND DOWN TO THE SURFACE. WE CARRIED A MENTION OF THIS POTENTIAL IN THE HAZARDOUS WEATHER OUTLOOK /HWO/. ALL THE HOURLY GRIDS WERE UPDATED TO REFLECT THE LATEST CONDITIONS AND EXPECTED TRENDS THROUGH THE AFTERNOON. WE BUMPED UP THE WINDS SOME AS WELL THROUGH THE AFTERNOON GIVEN THE TIGHTENING PRESSURE GRADIENT AND WITH ADDED VERTICAL MIXING. AS THE AREA OF LOW PRESSURE TRACKS WELL TO OUR NORTH TONIGHT, THE COLDEST AIR WILL REMAIN NORTH OF OUR CWA BUT WE WILL HAVE A FEW HOURS OF POSSIBLY STRONG GUSTS ESPECIALLY AFTER MIDNIGHT. WINDS MAY GUST TO 40 MPH WITH AND JUST BEHIND THE FRONT. WITH THE UPPER FLOW STRONGEST OVER OUR NORTHERN ZONES, THE SURFACE FRONT AND CLOUDS WILL CLEAR THE NORTHERN ZONES BUT TAKE A FEW HOURS LONGER IN THE SOUTH. WITH THAT, THE TEMPERATURES WILL PLUNGE DOWN INTO THE MID 20S NORTHERN AREAS AND STILL BE IN THE MID 40S BY DAYBREAK SOUTH. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... RATHER QUIET PERIOD AS HIGH PRESSURE SLIDES EAST WEDNESDAY INTO THURSDAY WITH CLEAR SKIES BUT MUCH COOLER TEMPERATURES IN THE 40S AND 50S. WEDNESDAY NIGHT LOWS DOWN INTO THE UPPER TEENS NORTH TO THE FREEZING MARK SOUTHERN AREAS AND HIGHS ON THURSDAY IN THE 50S WITH THE EXCEPTION OF THE 40S FAR NORTH. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... THERE IS CONSIDERABLE MODEL DIVERSITY FOR THIS FORECAST PACKAGE AND THEREFORE WE HAVE VERY LOW CONFIDENCE IN THE OUTCOME. THE 00Z ECMWF IS CONSIDERABLY DIFFERENT FROM THE 12Z GFS/UKMET/GLOBAL CANADIAN. WITH EDT IN EFFECT IT MAKES IT HARD TO SEE WHAT THE ECMWF WILL DO NEXT. PERHAPS THE NEXT SHIFT WILL HAVE THE OPPORTUNITY TO SEE SOME BETTER BALANCE BETWEEN THE MODELS. LATE THURSDAY BEGINS THE NEXT ROUND OF SEVERAL DAYS WITH PRECIPITATION IN THE FORECAST. THE PRECIPITATION WILL BE PRIMARILY RAIN HOWEVER THERE REMAINS THE POSSIBILITY FOR A MIXED BAG AS YOU HEAD NORTH THROUGH THE CWA. HIGH PRESSURE OVER THE REGION WILL MOVE OFFSHORE THURSDAY AS LOW PRESSURE DEVELOPS OVER THE SOUTHERN PLAINS AND MOVES EASTWARD. BY 12Z FRIDAY THIS LOW IS FORECAST TO BE OVER THE OHIO VALLEY. THIS IS SEEN IN GFS/UKMET AND CANADIAN. THE ECMWF HAS THIS FEATURE OVER THE SOUTHERN PLAINS BY 12Z FRIDAY. AS THE LOW MOVES EASTWARD IT IS FORECAST TO INTENSIFY. A WARM FRONT WILL CROSS THE REGION BY FRIDAY EVENING WITH THE COLD FRONT MOVING THROUGH FRIDAY NIGHT. THE MODELS DO DIFFER AS TO WHERE TH LOW WILL END UP BY 00Z SATURDAY BUT THE CONSENSUS SEEMS TO BE AS FAR WEST AS WESTERN NEW YORK OR AS FAR EAST AS NORTHEASTERN PENNSYLVANIA. THE LOW EVENTUALLY MOVES OFF TO THE NORTHEAST AND IS OVER THE CANADIAN MARITIMES BY 12Z SATURDAY. WE MAY SEE SOME DRY SPOTS OVER THE EARLY PART OF THE WEEKEND BUT WITH THE HIGH UNCERTAINTY OF THIS FORECAST WE HAVE DECIDED TO LEAVE SCHC POPS IN ACROSS THE REGION. WEAK HIGH PRESSURE BUILDS IN SATURDAY AS A POSSIBLE LOW PRESSURE SYSTEM BEGINS TO MOVE UP THE EASTERN SEABOARD SATURDAY NIGHT. THE PERIOD ENDS WITH HIGH PRESSURE BUILDING IN FROM THE WEST. HPC AND GFS MOS GUIDANCE DIFFERED QUITE A BIT WHEN IT CAME TO TEMPERATURES WITH THE GMOS MUCH COLDER IN THE NORTHERN HALF OF THE CWA FOR MAJORITY OF THE EXTENDED. THEREFORE, STUCK WITH HPC THROUGHOUT THE ENTIRE PERIOD /WITH SOME MINOR ADJUSTMENTS/ IN ORDER TO KEEP A BETTER CONTINUITY WITH THE PREVIOUS FORECAST. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... DESPITE ALL THE TERMINALS IN THE WARM SECTOR, PLENTY OF LOW CLOUDS PERSIST AS AN ABUNDANCE OF MOISTURE IS IN PLACE. VISIBLE SATELLITE AND SURFACE OBSERVATIONS ACROSS NORTHERN VIRGINA TO WESTERN MARYLAND INDICATE THAT THE CLOUDS HAVE THINNED OUT WITH CEILINGS GREATLY IMPROVING. THIS IS EDGING EASTWARD, HOWEVER ADDITIONAL SHOWERS ARE FORMING ACROSS EASTERN PENNSYLVANIA. THE LATEST THINKING IS THAT SOME IMPROVEMENT WILL OCCUR BY LATER THIS AFTERNOON, PROBABLY TO AROUND MARGINAL VFR. TERMINALS SEEING THIS OCCUR WILL PROBABLY BE ONES THAT ARE FARTHER TO THE SOUTH. IT SHOULD BE NOTED THAT ANY IMPROVEMENT IN CEILINGS CARRIES LOWER CONFIDENCE ATTM. WE WILL CONTINUE TO ISSUE AMENDMENTS TO REFLECT THE LATEST THINKING. SOME THUNDER IS STILL POSSIBLE MAINLY LATER THIS AFTERNOON AND EARLY EVENING, AND WE WILL TRANSITION TO A TEMPO GROUP WITH A CB DESCRIPTOR TO INDICATE THIS POSSIBILITY. THE SOUTHERLY FLOW HAS INCREASED ACROSS ALL AREAS AND WILL CONTINUE. PLENTY OF WIND ENERGY ABOVE THE SURFACE, THEREFORE SOME LOW-LEVEL WIND SHEAR WILL BE AROUND DESPITE THE STRONGER WINDS GRADUALLY SLIDING TO THE EAST LATER THIS AFTERNOON. AFTER FRONTAL PASSAGE IN THE 00Z TO 02Z TIME FRAME FROM WEST TO EAST, IMPROVING CONDITIONS /TO VFR/ SHOULD COMMENCE, WITH CLEARING OCCURRING AFTER 03Z TO 05Z. WESTERLY WINDS VEERING TO WEST AND NORTHWEST SHOULD BE RATHER GUSTY IN THE POST-FRONTAL ENVIRONMENT IN THE EVENING AND INTO THE OVERNIGHT PERIOD. OUTLOOK... IT SHOULD REMAIN RATHER BREEZY INTO WEDNESDAY. HIGH PRESSURE AND DRY CONDITIONS SHOULD FOLLOW FOR WEDNESDAY INTO EARLY THURSDAY. THE CHANCE FOR RAIN AND LOWERING CONDITIONS RETURNS FROM LATE THURSDAY INTO EARLY SATURDAY. && .MARINE... WINDS ARE GUSTING TO ABOUT 25 KNOTS AND AN EARLY REPORT FROM THE CAPE MAY-LEWES FERRY INDICATED WINDS TO 25 KNOTS ALSO IN THE LOWER DELAWARE BAY, THEREFORE THE SMALL CRAFT ADVISORY REMAINS IN EFFECT. STABILITY FACTORS WILL PRECLUDE THE STRONGEST WINDS OFF THE SURFACE FROM MIXING DOWNWARD UNTIL THE SURFACE FRONT MOVES PAST THIS EVENING. SEAS ARE MORE THAN 5 FEET ON THE OCEAN, AND LIKELY NEAR 5 FT AROUND THE MOUTH OF LOWER DELAWARE BAY, SO THE EXISTING SMALL CRAFT ADVISORY WILL BE KEPT IN PLACE FOR THESE LOCATIONS. THE TIME FOR THE UPPER BAY TO NEED AN ADVISORY, EARLIER PLANNED TO DEVELOP BY 12Z, STILL LOOKS LIKE A GOOD TIME AND WILL BE RETAINED. EVEN IF THAT IS AN HOUR OR A COUPLE OF HOURS EARLY, THAT WILL ALLOW FOR SOME POSITIVE LEAD TIME FOR THE EXPECTED CONDITIONS. OTHERWISE, SMALL CRAFT ADVISORY CONDITIONS WILL CONTINUE THROUGH FRONTAL PASSAGE THIS EVENING. THEN, WITH TURBULENT FLOW MIXING DOWN TO THE SURFACE, AND 925 HPA WINDS SHOWN IN THE 35 TO 45 KNOT RANGE TONIGHT, A GALE WARNING WILL BE ISSUED FOR EXPECTED GUSTS OF AROUND 35 KNOTS FROM 02Z TO 12Z WEDNESDAY. POST-COLD FRONTAL NORTHWEST WINDS WILL BE BLUSTERY INTO WEDNESDAY, BUT WILL DROP OFF WEDNESDAY AFTERNOON AND ALLOW CONDITIONS TO DROP BELOW ADVISORY CRITERIA AS HIGH PRESSURE MOVES BACK IN. THE HIGH WILL INFLUENCE OUR WEATHER THROUGH THURSDAY. ANOTHER LOW MOVING UP TO OUR WEST COULD BRING US ADVISORY CONDITIONS LATE THURSDAY INTO FRIDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ430- 431-450>455. GALE WARNING FROM 10 PM THIS EVENING TO 8 AM EDT WEDNESDAY FOR ANZ430-431-450>455. && $$ SYNOPSIS...EBERWINE/GORSE NEAR TERM...EBERWINE/GORSE SHORT TERM...EBERWINE LONG TERM...MEOLA AVIATION.../ GORSE MARINE.../ GORSE
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1023 AM CDT TUE APR 1 2008 .UPDATE...SHORT WAVE TROF THAT BROUGHT WIDESPREAD SNOWS TO THE SE TWO THIRDS OF THE DLH CWA OVERNIGHT CONTINUES TO PULL AWAY FROM THE WRN GREAT LAKES REGION LATE THIS MORNING..WITH HEAVY SNOWS NOW CONFINED TO THE EASTERN UPPER PENINSULA OF MICHIGAN. THERE MAY BE A SHORT WINDOW OF OPPORTUNITY FOR A FEW LIGHT LAKE EFFECT SNOW SHOWERS IN ASHLAND/IRON COUNTIES..BUT OVERALL LOW LEVEL FLOW WILL BE WEAKENING/BACKING TO A MORE WESTERLY DIRECTION RATHER RAPIDLY WITH TIME OVER THE NEXT FEW HOURS..AND THIS WILL BE CONCURRENT WITH AN INJECTION OF DRIER AIR IN THE LOW LEVELS..SO OVERALL CHANCES OF ANY ADDITIONAL PRECIPITATION ARE DECREASING FAST. THE PRIMARY CONCERNS FOR THIS UPDATE ARE TEMPS/SKY COVER AND WINDS/WAVES. NEW SNOW COVER WUD ARGUE FOR LOWERING TEMPS SOMEWHAT OVER CENTRAL MN/NW WISCONSIN..BUT TEMPS DID NOT COOL TOO MUCH OVERNIGHT AND ARE STARTING OUT IN THE MID-UPPER 20S. SO..WITH WARM EARLY APRIL SUN..MID TO MAYBE EVEN UPPER 30S DONT SEEM A STRETCH..ESPECIALLY WITH ONLY THIN HIGH LEVEL CLOUDS LINGERING IN A FEW AREAS. WE HAVE ALSO DECREASED SKY COVER SIGNIFICANTLY FROM THE PREVIOUS GRIDDED FORECAST BASED PRIMARILY ON LATEST SATELLITE TRENDS..ALTHOUGH THERE WILL PROBABLY BE SOME CUMULUS FORMATION THIS AFTERNOON. WINDS WILL ALSO RAPIDLY DECREASE CENTRAL AND EAST THIS AFTERNOON AS LOW LEVEL RIDGING BUILDS IN AND GRADIENT WEAKENS BY 21Z. WITH STEEP LOW LEVEL LAPSE RATES BY THIS AFTERNOON AND APPROACHING WEAK S/W TROF OVER SRN MANITOBA..ITS NOT OUT OF THE QUESTION THAT THERE COULD BE A FEW LIGHT SHOWERS IN THE FAR NW ZONES..BUT CONFIDENCE IN THIS IS NOT HIGH ENUF TO PUT INTO THE FORECAST ATTM. UPDATES TO ALL GRIDS/TEXT PRODUCTS TO REFLECT THE AFOREMENTIONED THINKING ARE ALREADY AVAILABLE. FINALLY..AS WINDS SUBSIDE..WAVE HEIGHTS WILL DECREASE THIS AFTERNOON ON WRN LK SUPERIOR..AND CURRENT EXPIRATION OF SMALL CRAFT ADV ON THE NORTH SHORE AND SW TIP OF THE LAKE AT NOON AND THE SOUTH SHORE LATER THIS AFTERNOON APPEAR REASONABLE. MILLER && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR LSZ121- LSZ146-LSZ147-LSZ148. SMALL CRAFT ADVISORY UNTIL NOON CDT TODAY FOR LSZ140-LSZ141- LSZ142-LSZ143-LSZ144-LSZ145. && .PREV DISCUSSION... /ISSUED 757 AM CDT TUE APR 1 2008/ UPDATE...WE CANCELLED THE WINTER STORM WARNING THAT WAS STILL IN EFFECT FOR ASHLAND AND IRON COUNTIES. SPOTTERS...WEBCAMS AND OBSERVATIONS ALL INDICATE THE SNOW IS ENDING OR BECOMING LIGHT. FLOW WAS STILL NORTHERLY OVER LAKE SUPERIOR WITH 850MB TEMPS FORECAST TO BE AROUND -11C OR -12C...WHICH WOULD SUPPORT LAKE EFFECT SNOW SHOWERS. HOWEVER...A TAMDAR SOUNDING NEAR CYQT HAD AN 850MB TEMP A COUPLE DEGREES WARMER THAN THE MODELS FORECAST. WE DON`T EXPECT MUCH FROM THE LAKE TODAY DUE TO THE DRIER AIR AND SUBSIDENCE. PREV DISCUSSION... /ISSUED 619 AM CDT TUE APR 1 2008/ UPDATE...EXTENDED WARNING A COUPLE HOURS ACROSS ASHLAND AND IRON COUNTIES. STILL SOME SNOW BANDS WORKING THROUGH THAT AREA...WITH SOME LAKE ENHANCEMENT LIKELY AS CAA CONTINUES EARLY THIS MORNING. VSBYS AT KIWD CONTINUE TO BE 1 MILE OR LESS...AND SPOTTER AT GILE REPORTED CONTINUED HEAVY SNOW AND CONSIDERABLE BLOWING AND DRIFTING SNOW. SNOW AND WINDS SHOULD DIMINISH THERE THROUGH MID- MORNING AS DRIER AIRMASS ADVECTS EASTWARD. REMAINDER OF WARNING WAS ALLOWED TO EXPIRE...WITH JUST LIGHT SNOW EXPECTED NOW. PREV DISCUSSION... /ISSUED 317 AM CDT TUE APR 1 2008/ DISCUSSION...EARLY MORNING SURFACE ANALYSIS DEPICTS LOW PRESSURE CENTERED OVER NORTHERN LOWER MICHIGAN...WITH BACK DOOR TROUGH/COLD FRONT PUSHING ACROSS NW WI. DEFORMATION AXIS OF SNOW HAS PIVOTED AND IS NOW WEAKENING AND PULLING OFF TO THE EAST. LIGHT SNOW WITH OCCASIONAL HEAVIER BANDS WILL CONTINUE THROUGH EARLY MORNING AS SLOPING 2-D FGEN FORCING STILL EXISTS...SO WILL LEAVE WARNING ENDING TIME AS SCHEDULED. ALSO...SOME EVIDENCE EXISTS FOR DEVELOPING STANDING WAVE ALONG THE BAYFIELD PENINSULA AND SW TO NORTHERN PINE COUNTY. SNOW TOTALS RECEIVED THROUGH THIS EARLY MORNING GENERALLY RANGE FROM 4 TO 6 INCHES...WITH AN ISOLATED 11 INCH REPORT IN NORTHERN BAYFIELD COUNTY. SUSPECT THAT THERE WILL BE MORE HIGH END REPORTS LATER THIS MORNING...ESPECIALLY ALONG THE SOUTH SHORE WHERE VSBYS HAVE BEEN THE LOWEST OVERNIGHT. LOW WILL EXIT QUICKLY THIS LATE MORNING...WITH CAA AND DRIER AIRMASS BUILDING INTO THE REGION FROM THE WEST. HIGH PRESSURE UNDER WNW FLOW ALOFT WILL REMAIN IN CONTROL THROUGH THIS EVENING. A WEAK UPPER SHORT WAVE WILL PUSH THROUGH LATE TONIGHT AND WEDNESDAY. SOME SNOW MAY DEVELOP ON THE NOSE OF 40+ KT LLJ AND WARM FRONT PUSHING INTO NORTHERN MINNESOTA LATE TONIGHT AND WEDNESDAY MORNING. BROADER LIFT ACROSS WAA ZONE WEDNESDAY AND WED NIGHT WILL BRING THE CHANCE OF SOME LIGHT RAIN/SNOW...BUT OVERALL LIFT IS WEAK AND MOISTURE IS LIMITED. OTHERWISE...A NICE WARMING TREND LOOKS IN STORE FOR THE REMAINDER OF THE WEEK...WITH H85 TEMPS APPROACHING 0C BY 00Z SAT...AND SFC TEMPS ABOVE NORMAL. LOOKING AHEAD TO THIS SUNDAY...MODELS ARE ADVERTISING ANOTHER LOW DEVELOPING OFF THE NORTHERN ROCKIES...BRINGING A CHANCE OF RAIN/SNOW TO THE NORTHLAND. AVIATION...LOW PRESSURE WILL CONTINUE TO PULL OFF TO THE EAST TODAY...AND HIGH PRESSURE WILL BUILD INTO THE REGION. IFR/MVFR CEILINGS AND VSBYS WERE MAINLY OVER NORTHWEST WISCONSIN EARLY THIS MORNING...AND THEY WILL LIFT THROUGH THE DAY LEADING TO VFR CONDITIONS. GUSTY WINDS EARLY WILL DIMINISH THROUGH THE DAY AS WELL FROM WEST TO EAST ACROSS MINNESOTA AND WISCONSIN. && POINT TEMPS/POPS... DLH 35 17 42 26 / 10 10 20 20 INL 35 16 43 25 / 10 20 30 20 BRD 37 19 44 27 / 10 10 30 20 HYR 36 14 45 26 / 10 10 10 20 ASX 35 17 44 25 / 10 10 10 20 $$
AREA FORECAST DISCUSSION
NWS DULUTH MN
757 AM CDT TUE APR 1 2008 .UPDATE...WE CANCELLED THE WINTER STORM WARNING THAT WAS STILL IN EFFECT FOR ASHLAND AND IRON COUNTIES. SPOTTERS...WEBCAMS AND OBSERVATIONS ALL INDICATE THE SNOW IS ENDING OR BECOMING LIGHT. FLOW WAS STILL NORTHERLY OVER LAKE SUPERIOR WITH 850MB TEMPS FORECAST TO BE AROUND -11C OR -12C...WHICH WOULD SUPPORT LAKE EFFECT SNOW SHOWERS. HOWEVER...A TAMDAR SOUNDING NEAR CYQT HAD AN 850MB TEMP A COUPLE DEGREES WARMER THAN THE MODELS FORECAST. WE DON`T EXPECT MUCH FROM THE LAKE TODAY DUE TO THE DRIER AIR AND SUBSIDENCE. && .PREV DISCUSSION... /ISSUED 619 AM CDT TUE APR 1 2008/ UPDATE...EXTENDED WARNING A COUPLE HOURS ACROSS ASHLAND AND IRON COUNTIES. STILL SOME SNOW BANDS WORKING THROUGH THAT AREA...WITH SOME LAKE ENHANCEMENT LIKELY AS CAA CONTINUES EARLY THIS MORNING. VSBYS AT KIWD CONTINUE TO BE 1 MILE OR LESS...AND SPOTTER AT GILE REPORTED CONTINUED HEAVY SNOW AND CONSIDERABLE BLOWING AND DRIFTING SNOW. SNOW AND WINDS SHOULD DIMINISH THERE THROUGH MID- MORNING AS DRIER AIRMASS ADVECTS EASTWARD. REMAINDER OF WARNING WAS ALLOWED TO EXPIRE...WITH JUST LIGHT SNOW EXPECTED NOW. PREV DISCUSSION... /ISSUED 317 AM CDT TUE APR 1 2008/ DISCUSSION...EARLY MORNING SURFACE ANALYSIS DEPICTS LOW PRESSURE CENTERED OVER NORTHERN LOWER MICHIGAN...WITH BACK DOOR TROUGH/COLD FRONT PUSHING ACROSS NW WI. DEFORMATION AXIS OF SNOW HAS PIVOTED AND IS NOW WEAKENING AND PULLING OFF TO THE EAST. LIGHT SNOW WITH OCCASIONAL HEAVIER BANDS WILL CONTINUE THROUGH EARLY MORNING AS SLOPING 2-D FGEN FORCING STILL EXISTS...SO WILL LEAVE WARNING ENDING TIME AS SCHEDULED. ALSO...SOME EVIDENCE EXISTS FOR DEVELOPING STANDING WAVE ALONG THE BAYFIELD PENINSULA AND SW TO NORTHERN PINE COUNTY. SNOW TOTALS RECEIVED THROUGH THIS EARLY MORNING GENERALLY RANGE FROM 4 TO 6 INCHES...WITH AN ISOLATED 11 INCH REPORT IN NORTHERN BAYFIELD COUNTY. SUSPECT THAT THERE WILL BE MORE HIGH END REPORTS LATER THIS MORNING...ESPECIALLY ALONG THE SOUTH SHORE WHERE VSBYS HAVE BEEN THE LOWEST OVERNIGHT. LOW WILL EXIT QUICKLY THIS LATE MORNING...WITH CAA AND DRIER AIRMASS BUILDING INTO THE REGION FROM THE WEST. HIGH PRESSURE UNDER WNW FLOW ALOFT WILL REMAIN IN CONTROL THROUGH THIS EVENING. A WEAK UPPER SHORT WAVE WILL PUSH THROUGH LATE TONIGHT AND WEDNESDAY. SOME SNOW MAY DEVELOP ON THE NOSE OF 40+ KT LLJ AND WARM FRONT PUSHING INTO NORTHERN MINNESOTA LATE TONIGHT AND WEDNESDAY MORNING. BROADER LIFT ACROSS WAA ZONE WEDNESDAY AND WED NIGHT WILL BRING THE CHANCE OF SOME LIGHT RAIN/SNOW...BUT OVERALL LIFT IS WEAK AND MOISTURE IS LIMITED. OTHERWISE...A NICE WARMING TREND LOOKS IN STORE FOR THE REMAINDER OF THE WEEK...WITH H85 TEMPS APPROACHING 0C BY 00Z SAT...AND SFC TEMPS ABOVE NORMAL. LOOKING AHEAD TO THIS SUNDAY...MODELS ARE ADVERTISING ANOTHER LOW DEVELOPING OFF THE NORTHERN ROCKIES...BRINGING A CHANCE OF RAIN/SNOW TO THE NORTHLAND. AVIATION...LOW PRESSURE WILL CONTINUE TO PULL OFF TO THE EAST TODAY...AND HIGH PRESSURE WILL BUILD INTO THE REGION. IFR/MVFR CEILINGS AND VSBYS WERE MAINLY OVER NORTHWEST WISCONSIN EARLY THIS MORNING...AND THEY WILL LIFT THROUGH THE DAY LEADING TO VFR CONDITIONS. GUSTY WINDS EARLY WILL DIMINISH THROUGH THE DAY AS WELL FROM WEST TO EAST ACROSS MINNESOTA AND WISCONSIN. && POINT TEMPS/POPS... DLH 35 17 42 26 / 10 10 20 20 INL 37 16 43 25 / 10 20 30 20 BRD 38 19 44 27 / 10 10 30 20 HYR 38 14 45 26 / 40 10 10 20 ASX 35 17 44 25 / 60 10 10 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR LSZ121- LSZ146-LSZ147-LSZ148. SMALL CRAFT ADVISORY UNTIL NOON CDT TODAY FOR LSZ140-LSZ141- LSZ142-LSZ143-LSZ144-LSZ145. $$ MELDE/LILES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1007 AM EDT TUE APR 1 2008 .SYNOPSIS...BREEZY SOUTHERLY WINDS WILL SPREAD WARMER AIR OVER THE REGION TODAY. A COLD FRONT WILL APPROACH FROM THE WEST TODAY AND CROSS THE AREA TONIGHT. ANOTHER COOL HIGH PRESSURE AREA WILL BUILD IN FROM THE NORTH ON WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1000 AM... HAVE CUT BACK RAIN TO CHANCE CATEGORY. PRECIPITATION IMMEDIATELY AHEAD OF THE FRONT IS WEAKENING AND CONTINUING THIS TREND. BEST DYNAMICS FOR TODAY WILL BE IN THE EAST. AS TEMPERATURES WARM THIS AFTERNOON THERE IS ENOUGH INSTABILITY FOR A RISK OF A THUNDERSTORM ACROSS CENTRAL NORTH CAROLINA. SMALL HAIL CAN NOT BE RULED OUT WITH FREEZING LEVELS BELOW 10000 FEET... WITH POSSIBILITIES BETTER IN THE EAST. BOUNDARY AS DEFINED BY DEWPOINTS BETWEEN RALEIGH AND GREENSBORO WITH LOW 50S DEWPOINTS IN THE NORTHWEST. REAR EDGE OF THE UPPER CLOUDS WILL MOVE THROUGH CENTRAL NORTH CAROLINA BY EARLY EVENING. SURFACE FLOW BECOMES WEAKLY DIVERGENT. WITH SOUTHWEST FLOW ACROSS THE AREA... EXPECTING THE BOUNDARY TO ERODE/LIFT OUT. SOME BRIEF PEEKS AT THE SUN. HAVE MINIMALLY RAISED TEMPERATURES. EXPECT GOOD MIXING THIS AFTERNOON. WITH WINDS IN EXCESS OF 25 KNOTS EXPECTED TO BE TAPPED...SOME GUSTINESS SHOULD DEVELOP LATE MORNING INTO THE AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... AS OF 320 AM TUESDAY... SURFACE COLD FRONT STILL ON TRACK TO CROSS THE REGION LATE TONIGHT THEN STALL NEAR OR JUST SOUTH OF THE REGION WEDNESDAY. COOL HIGH PRESSURE OVER THE GREAT LAKES WILL TRANSLATE EAST INTO THE NORTHERN MID ATLANTIC AND BUILD SOUTH INTO NC WED AND WED NIGHT. THIS SCENARIO WILL SUPPORT ANOTHER COLD AIR DAMMING SITUATION (BUT SHOULD NOT BE AS LONG IN DURATION AS RECENT EVENT). 925-850MB S-SW FLOW WILL INCREASE LATE WED NIGHT INTO THU...INCREASING ISENTROPIC LIFT FROM S-N ACROSS THE REGION. WILL BOOST POPS THU TO HIGH CHANCE (WILL PROBABLY NEED TO INCREASE TO LIKELY OR LOW CATEGORICAL IN LATER FORECAST ISSUANCES IF LATER MODEL GUIDANCE CONSISTENT). WITH OVERCAST SKIES AND POTENTIAL FOR MORE RAIN...COOL TEMPS ANTICIPATED FOR THU. WITH HYBRID DAMMING SET-UP...LOWERED MAX TEMPS A FEW DEGREES IN THE NW PIEDMONT AND MAY NEED ADJUSTMENTS REMAINDER OF THE PIEDMONT. MODELS CURRENTLY IN GENERAL AGREEMENT ERODING CAD AIRMASS THU NIGHT WITH MOIST WARM AIR MASS OVER THE REGION FRI INTO FRI NIGHT. EXPECT TO SEE AN INCREASE IN SHOWERS FRI NIGHT INTO EARLY SATURDAY AS NEXT COLD FRONT APPROACHES. TEMPS WILL BE ON A ROLLER COASTER RIDE THIS WEEK. AFTER HIGHS TODAY IN THE 60S/70S EXPECT A DOWNTURN WED INTO THU WITH MAX TEMPS WED NEAR 60 NORTH TO MID 60S SOUTH..AND UPPER 40S NW TO LOWER 60S SE THU. WARM SLY FLOW FRI WILL BOOST TEMPS BACK INTO THE 70S FRI. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 300 AM TUESDAY... THE LATEST 00Z/01 GFS IS BEGINNING TO TREND TOWARDS THE SLOWER DETERMINISTIC SOLUTION OF THE ECMWF...INDICATING COLD FRONT PASSAGE EXTENDING INTO THE AFTERNOON AND EVENING HOURS ON SATURDAY. THE SLOWER TIMING IS ALSO IN BETTER AGREEMENT WITH THE GFS ENSEMBLE MEAN. AS A RESULT...HAVE RAISED POPS TO CHANCE DURING THE DAY ON SATURDAY...CONTINUING THE CHANCE OF SHOWERS AND THUNDERSTORMS...WITH MODELS SHOWING A MODERATELY AMPLIFIED TROUGH ALOFT...FAVORABLE RR JET DYNAMICS...AND STRONG DEEP (0 TO 6KM) LAYER SHEAR OF 45 TO 50KTS. CLOUDS AND MOISTURE EXIT THE AREA OVERNIGHT SATURDAY NIGHT AS HIGH PRESSURE BUILDS IN FROM THE WEST. UPPER FLOW REGIME LOOKS TO STAY FLAT AND PROGRESSIVE INTO EARLY NEXT WEEK. SUNDAY AND MONDAY WILL REMAIN DRY WITH SEASONABLE TEMPERATURES. HIGHS 65 TO 70. LOWS IN THE 40S. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... AS OF 130 AM TUESDAY... CLASSICAL DIABATICALLY ENHANCED COLD AIR DAMMING EVENT AND ASSOC IFR/LIFR CONDITIONS CONTINUES ACROSS WESTERN PORTIONS OF THE FORECAST AREA. LATEST OBSERVATION FROM THE RDU INTERNATIONAL REPORTS 2M SURFACE WINDS HAVE SWITCHED AROUND TO SOUTHERLY...INDICATING WEDGE BOUNDARY(WARM FRONT)HAS JUST PUSHED WEST OF THE AREA. HARD TO DETERMINE IF THIS IS PERMANENT...OR JUST TEMPORARILY...AS BOUNDARY HAS BEEN MEANDERING WEST AND EAST OVER THE PAST EVENING. EXPECT TO SEE IMPROVED IMPROVED CEILINGS/VISIBILITIES IN THE WARM SECTOR...EAST OF THE TRIANGLE...WITH VISIBILITIES RANGING FROM MVFR TO VFR AND CEILINGS RANGING FROM 200 TO 2000 FT...WITH LOWEST CONDITIONS EXPECTED RIGHT ALONG THE FRONT AT THE RDU. IN THE WESTERN PIEDMONT...WHERE WEDGE CONTINUES TO HANG TOUGH...LIFR TO IFR CEILINGS AND VISIBILITIES. ALSO...AREA AMDAR AIRCRAFT SOUNDINGS SHOW STRONG SOUTHERLY LOW LEVEL JET AND SHEAR OVER THE WEDGE REGIME...WITH 35 TO 40KTS AT OR ABOVE 1500FT...ATOP NEARLY CALM OR LIGHT NE WINDS. WILL INCLUDE NON CONVECTIVE LOW LEVEL WIND SHEAR FOR JUST KINT AND KGSO THROUGH 12Z. VISIBILITIES SHOULD REBOUND INTO THE VFR CATEGORY BY MIDDAY TUESDAY (FROM EAST TO WEST) AS THE AIR NEAR THE SURFACE BECOMES WELL MIXED (850 SOUTHWEST WINDS 45 TO 50 KTS) OUT AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. CEILINGS MAY BRIEFLY LIFT TO THE HIGH END OF MVFR OR LOW END OF VFR BY TUESDAY AFTERNOON. HEATING OF THE MOIST AND MARGINALLY UNSTABLE AIR MASS MAY LEAD TO THE DEVELOPMENT OF SCATTERED SHOWERS OR THUNDERSTORMS TUESDAY AFTERNOON...ESPECIALLY IN THE COASTAL PLAIN REGION. THESE SHOWERS/STORMS MAY PERSIST INTO TUESDAY NIGHT AS A COLD FRONT CROSSES THE REGION. SOUTHWEST WINDS WILL LIKELY BECOME BREEZY TUESDAY AFTERNOON AHEAD OF THE FRONT...BECOMING SUSTAINED AT 10-15 KNOTS WITH GUSTS UP TO 25 KNOTS. MAY SEE ANOTHER COLD AIR DAMMING EVENT WITH ASSOCIATED LOW CEILINGS/VISIBILITIES WED NIGHT THROUGH THUR NIGHT AS ANOTHER STRONG ARE OF HIGH PRESSURE BUILDS ACROSS THE NORTHERN MID ATLANTIC REGION. ANOTHER COLD FRONT IS EXPECTED TO APPROACH FROM THE WEST FRIDAY AFTERNOON...AND CROSS THE AREA EARLY SATURDAY. THIS COULD RESULT IN MORE UNSETTLED WEATHER AT THAT TIME. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$