Area Forecast Discussion
Issued by NWS Wilmington, NC

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KILM 091754 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1254 PM EST TUE FEB 9 2010 .SYNOPSIS... A DEVELOPING AREA OF LOW PRESSURE OFF THE CAROLINA COAST WILL MOVE NORTHEAST OF THE AREA THIS EVENING BEFORE BEGINNING TO RAPIDLY INTENSIFY LATE TONIGHT AND WEDNESDAY. THIS WILL CREATE A VERY TIGHT PRESSURE GRADIENT ACROSS THE AREA WHICH WILL LINGER INTO THURSDAY AS THE STORM DEEPENS FURTHER SOUTHEAST OF NEW ENGLAND. THE NEXT IN THE PARADE OF LOW PRESSURE SYSTEMS WILL MOVE BY TO OUR SOUTH FRIDAY NIGHT AND SATURDAY BRINGING A CHANCE OF SNOW. HIGH PRESSURE WILL BUILD IN FOR THE LATTER HALF OF THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 11 AM TUESDAY...CHARACTER OF PRECIPITATION LOOKS MORE SHOWERY THAN STRATIFORM PER RADAR REPRESENTATIONS. THEREFORE...CHANGED RAIN TO SHOWERS AND GIVEN THE LIGHTNING STRIKES TO OUR S AND WITH LOW PRESSURE CLOSING OFF TO OUR S...WILL INCLUDE MENTION OF THUNDERSTORMS THROUGHOUT THE FORECAST AREA. OTHER SIGNIFICANT CHANGES INCLUDED RAISING MAXIMUMS FOR TODAY GIVEN THE INFLUX OF MILDER AIR THAT IS BEING ENTRAINED INTO THE COASTAL LOW. ALSO...BASED ON RADAR TRENDS AND WITH SYSTEM ORGANIZING QUICKER THAN PREVIOUSLY THOUGHT...RAISED QPF AMOUNTS TO ONE-HALF TO ALMOST AN INCH. THE SIGNIFICANT QPF IS EXPECTED TO OCCUR THIS AFTERNOON AND EVE AS LOW PRESSURE MOVES NORTHEAST ALONG THE CAROLINA COAST. THERE MAY BE A PERIOD OF MUCH LIGHTER RAIN WITH THE PASSAGE OF A COLD FRONT OVERNIGHT. SOUTH WINDS WILL SHIFT TO WEST NORTHWEST WITH THE PASSAGE OF A COLD FRONT OVERNIGHT WITH WINDS INCREASING SHARPLY AS STRONG MIXING ENSUES AND BRINGS HIGHER MOMENTUM AIR ALOFT TO THE SURFACE. A WIND ADVISORY WILL LIKELY BE ISSUED LATER TODAY FOR THE STRONG WINDS THAT ARE EXPECTED TO DEVELOP BEGINNING VERY LATE TONIGHT. THE STRONGEST WINDS WILL LIKELY OCCUR WED AFTERNOON AND EVE AS LOW PRESSURE BOMBS SOUTH OF NEW ENGLAND. TEMPS WILL FALL SHARPLY WITH THE PASSAGE OF THE COLD FRONT AFTER MIDNIGHT. TEMPS IN THE LOWER TO MID 30S AT SUNRISE WED WILL COMBINE WITH THE STRONG WINDS TO MAKE IT FEEL AS IF IT WERE WELL DOWN IN THE 20S. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...ARCTIC HIGH BUILDING IN BEHIND EXITING COLD FRONT WILL ENSURE TEMPERATURES THROUGH THE PERIOD REMAIN WELL BELOW CLIMO. DEEP MIXING WED...FORECAST SOUNDINGS ARE DRY ADIABATIC TO OVER 7K FT...WILL ENSURE 40 TO 45 MPH WINDS AT 2K FT MIX DOWN AS GUSTS. IN ADDITION TO THE GUSTS...TIGHT GRADIENT AND STRONG COLD ADVECTION PRODUCE SUSTAINED WEST TO NORTHWEST WINDS OVER 20 MPH...FWIW MOS IS FORECASTING WIND SPEEDS WED AROUND 25 MPH. COLD ADVECTION STARTS TO WANE WED NIGHT BUT CONDITIONS REMAIN BREEZY WITH WINDS CLOSE TO 15 MPH. LOWS WILL BE IN THE MID TO UPPER 20S DESPITE GOOD MIXING. HIGH PRESSURE REMAINS IN CONTROL THU BUT GRADIENT STARTS TO RELAX. LOW PRESSURE ACCELERATES AWAY FROM THE MID ATLANTIC COAST AND CENTER OF HIGH MOVES CLOSER. THU WILL BE BREEZY...BUT WINDS WILL BE ALMOST HALF OF WHAT WE EXPERIENCE WED. AIR MASS STARTS TO WARM UP THU WITH FULL SUN AND NO COLD ADVECTION...BUT HIGH WILL STILL END UP ALMOST 10 DEGREES BELOW CLIMO. LIGHT WINDS AND DRY AIR THU NIGHT MAY END UP MAKING THU NIGHT A FEW DEGREES COOLER THAN WED NIGHT...ESPECIALLY FOR TYPICAL COLD SPOTS. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM TUESDAY...MAIN CONCERN FOR THE PERIOD IS GULF LOW CROSSING SOUTHERN FL FRI INTO SAT. LATEST GFS KEEPS THE LOW WELL SOUTH OF THE AREA...MOVING ACROSS THE BAHAMAS. THE CANADIAN TURNS IT NORTHEAST AFTER IT CROSSES FLORIDA AND PASSES THE LOW A COUPLE HUNDRED MILES OFF THE SOUTHEAST COAST. LATEST ECMWF IS IN BETWEEN THESE 2 SOLUTIONS AND OFFERS A NICE COMPROMISE...AND IS ALSO CLOSE TO HPC. THIS SOLUTION WOULD RESULT IN A SOME PRECIP BRUSHING THE AREA FRI NIGHT...AS SNOW OR A MIX OF RAIN AND SNOW. PREVIOUS FORECAST WAS ALONG THESE LINES SO LARGE CHANGES NEEDED FOR THE WEEKEND. HIGH PRESSURE BUILDS IN LATER SAT THROUGH SUN BEFORE ANOTHER POTENTIAL SHOT AT WINTER WEATHER IMPACTS THE AREA LATE IN THE FORECAST. STILL A LOT OF UNCERTAINTY FOR MON BUT THE GFS/CANADIAN/ECMWF ALL AGREE ON STRONG SHORTWAVE CROSSING THE AREA. FOR NOW WILL HOLD ONTO SILENT POPS FOR MON. SEMI-PERMANENT LARGE AMPLITUDE 5H TROF OVER THE EASTERN US WILL KEEP TEMPERATURES BELOW TO WELL BELOW CLIMO THROUGH THE PERIOD. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
AS OF 12Z...DEVELOPING LOW OVER THE PANHANDLE OF FLORIDA WILL PASS THROUGH THE TERMINAL AREAS DURING THE PERIOD. AS THE SYSTEM APPROACHES THE TAF SITES...SHOWERS AND A POSSIBLE THUNDERSTORM WILL DEVELOP. THE LOW PRESSURE AND ITS ASSOCIATED COLD FRONT WILL MOVE RAPIDLY THROUGH THE AREA DURING THE PERIOD. BECAUSE OF THIS RAPID MOVEMENT AND DEVELOPMENT THE WINDS WILL PICK UP IN INTENSITY AND VEER FROM EAST AT 12 TO 22 KNOTS THROUGH 23Z...THEN BECOME SOUTHERLY AT 10 TO 20 KNOTS UNTIL 08Z THEN FINALLY SHIFT TO THE WEST AT 15 TO 25 KNOTS WITH GUSTS TO 30 KNOTS WITH FRONTAL PASSAGE. EXTENDED OUTLOOK...HIGH CONFIDENCE VFR WEDNESDAY THROUGH FRIDAY. MEDIUM CONFIDENCE FOR PERIODS OF MVFR SATURDAY AS UPPER LEVEL SHORT WAVE TROUGH BRINGS SHOWERS. SUNDAY STARTS VFR THEN AS COLD FRONT APPROACHES FROM THE WEST...PERIODS OF MVFR/IFR WITH SHOWERS.
-- End Changed Discussion --
&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 11 AM TUESDAY...SMALL CRAFT ADVISORY CONDITIONS WILL DEVELOP THIS AFTERNOON AND EVE WITH A GALE WARNING IN EFFECT LATE TONIGHT. ON THE BACKSIDE OF DEPARTING LOW PRESSURE...WINDS WILL BEGIN TO INCREASE AFTER MIDNIGHT...INCREASING FURTHER ON WED AS THE PRESSURE GRADIENT SIGNIFICANTLY TIGHTENS AS LOW PRESSURE BOMBS SOUTH OF NEW ENGLAND. SOUTHERLY WINDS TODAY WILL SHIFT TO THE WEST NORTHWEST WITH THE PASSAGE OF A COLD FRONT AFTER MIDNIGHT. SEAS WILL BUILD THROUGH THE DAY ON SOUTHERLY WINDS. MUCH STRONGER WINDS WILL BEGIN TO DEVELOP TONIGHT...ESPECIALLY AFTER MIDNIGHT. SINCE THE STRONGEST WINDS WILL OCCUR WHEN THE WIND DIRECTION IS WEST NORTHWEST...SEAS WILL NEVER FULLY DEVELOP. THEREFORE...SEAS WILL NOT REACH LEVELS THAT WIND SPEEDS ALONE WOULD INDICATE. STILL WE DO EXPECT SEAS TO REACH ABOVE 6 FT WITHIN 20 NM...HIGHEST SEAS WILL OCCUR OVERNIGHT AND WED. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...STRONG OFFSHORE FLOW WED AND WED NIGHT WILL REQUIRE CONTINUATION OF HEADLINES. RIGHT NOW LOOKS LIKE EVENT WILL BE STRONG SCA...BUT CANNOT RULE OUT POSSIBILITY OF A PERIOD OF GALE STRENGTH WINDS. WINDS REMAIN OFFSHORE THU...BUT SPEEDS START TO DECREASE IN THE AFTERNOON AS GRADIENT RELAXES. NORTHWEST WINDS WILL KEEP HIGHEST SEAS BEYOND 20 NM AND RESULT IN A LARGE GRADIENT BETWEEN SEAS NEAR SHORE AND CLOSE TO 20 NM GENERALLY SEAS WILL BE BELOW 6 FT...THOUGH AT THE TIME OF STRONGEST WINDS SEAS AROUND 20 NM COULD BE AS HIGH AS 9 FT NEAR FRYING PAN SHOALS. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...OFFSHORE FLOW THROUGH THE PERIOD BUT SOME UNCERTAINTY DOES EXIST. LOW PRESSURE CROSSING FL FRI WILL TURN NORTHEAST AT SOME POINT. DIFFERENCES BETWEEN LATEST GFS/ECMWF AND CANADIAN ALL HAVE RAMIFICATIONS FOR COASTAL WATERS FORECAST. ECMWF SOLUTION IS CLOSE TO A COMPROMISE BETWEEN THE CANADIAN AND GFS AND IS THE SOLUTION CURRENTLY BEING FAVORED. OFFSHORE FLOW 10 KT OR LESS FRI WILL INCREASE INTO SAT ENDING UP NEAR 20 KT AS THE PASSES. SEAS WITHIN 20 NM MILES SHOULD REMAIN BELOW HEADLINE CRITERIA. && .ILM WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
SC...WIND ADVISORY FROM 8 AM TO 8 PM EST WEDNESDAY FOR SCZ017-023- 024-032>034-039-046. NC...WIND ADVISORY FROM 8 AM TO 8 PM EST WEDNESDAY FOR NCZ087-096- 097-099>101. MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 3 AM EST WEDNESDAY FOR AMZ254-256. GALE WARNING FROM 3 AM WEDNESDAY TO 5 AM EST THURSDAY FOR AMZ250-252-254-256. SMALL CRAFT ADVISORY UNTIL 3 AM EST WEDNESDAY FOR AMZ250-252.
-- End Changed Discussion --
&& $$ SYNOPSIS...RGZ NEAR TERM...RJD SHORT TERM...RGZ LONG TERM...RAS AVIATION...MDC

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.