Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 030752 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 352 AM EDT MON AUG 3 2015 .SYNOPSIS... LOW PRESSURE WILL MOVE ALONG A STATIONARY BOUNDARY DRAPED ALONG THE COAST THROUGH TUESDAY...BRINGING SHOWERS AND THUNDERSTORMS TO MUCH OF THE AREA. THIS LOW PRESSURE WILL MOVE AWAY TUESDAY NIGHT...FOLLOWED BY BERMUDA HIGH PRESSURE CREATING TYPICAL SUMMERTIME WEATHER THROUGH THE REMAINDER OF THE WEEK. A COLD FRONT WILL CROSS ON SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM SUNDAY...LINE OF SHOWERS HEADING TOWARDS THE COAST IS NOW FROM 15 TO 20 NM OFFSHORE AND SHOULD BE SKIRTING BALD HEAD ISLAND SHORTLY. STILL EXPECTING A GRADUAL RAMPING UP OF POPS THROUGH THE EARLY MORNING HOURS AS THE LOW PRESSURE SYSTEM CURRENTLY OVER NORTHERN FLORIDA MOVES NE ALONG A STALLED FRONTAL BOUNDARY. BOTH THE GFS AND NAM SHOW LOW LEVEL WIND FIELDS BACKING WITH HEIGHT THUS INCREASING CONVERGENCE BASICALLY ALONG THE COAST...THIS OCCURS AFTER 0600 UTC. THE GFS HAS BACKED OFF SLIGHTLY WITH THE 1200 RUN WHILE THE NAM REMAINS THE MOST AGGRESSIVE. I AM CONTINUING TO ADVERTISE GOOD CHANCE POPS ALONG THE IMMEDIATE COAST WITH MUCH HIGHER AMOUNTS OFFSHORE. FOLKS WEST OF I-95 WILL PROBABLY MISS OUT ENTIRELY. THE NAM IS ADVERTISING 0.25 TO 0.50 FOR THE SIX HOUR PERIOD WHILE THE GFS JUST UNDER A TENTH. MY EXPERIENCE SHOWS THAT ALTHOUGH MOST AREAS...ALONG THE COAST RECEIVE RAINFALL...THE QPF IS LIGHT AS THE HEAVIER ACTIVITY RESIDES JUST OFFSHORE. THIS IS PROBABLY WHAT WE WILL SEE THROUGH 1200 UTC. I LIKE THE SLIGHTLY WARMER GFS/MAV NUMBERS FOR LOWS WITH ALL OF THE CLOUD COVER MOVING IN. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 300 AM MONDAY...BIG CHANGES IN THE GUIDANCE FROM LAST NIGHT...BUT FORTUNATELY HAVE BEEN HANDLED WELL BY THE AFTN FORECASTER. LOW PRESSURE MOVING ALONG A STALLED BOUNDARY WILL BE PUSHING SLOWLY NE JUST OFF THE COAST TUESDAY MORNING. NHC GIVES THIS A 10% CHANCE OF DEVELOPING INTO A TROPICAL SYSTEM...AND GUIDANCE IS DEVELOPING A WEAK ASYMMETRIC WARM CORE...BUT IT PROBABLY WILL NOT HAVE ENOUGH TIME TO BECOME ANYTHING TRULY TROPICAL. REGARDLESS...VERY MOIST AIRMASS NOTED BY PWATS OVER 2.25 INCHES ALONG THE COAST WILL SUPPORT PERIODS OF HEAVY RAINFALL THE FIRST HALF OF TUESDAY BEFORE THIS LOW SKIRTS OFF TO THE NE. SREF PROBS ARE WELL OVER 80% FOR THE COASTAL COUNTIES...BUT TOWARDS I-95...AREAS THAT TRULY NEED THE RAIN...WILL SEE MUCH LIGHTER AMOUNTS THANKS TO A MUCH DRIER AIRMASS. WILL BUMP POP TO LIKELY TUESDAY MORNING BEFORE SLOWLY WINDING DOWN TUESDAY NIGHT. BY WEDNESDAY...LOW PRESSURE WILL BE WELL AWAY FROM THE AREA WITH RIDGING DEVELOPING ALOFT. THIS WILL LEAD TO MORE TYPICAL SUMMERTIME CONVECTION CHANCES...ALTHOUGH WILL MAINTAIN SUB-CLIMO POP DUE TO SUBSIDENCE ALOFT AND A DRIER COLUMN. TEMPS TUESDAY WILL FEATURE A WIDE RANGE ACROSS THE CWA. TEMPS ALONG THE IMMEDIATE COAST...ESPECIALLY THE CAPE FEAR COAST...MAY STRUGGLE OUT OF THE MID 80S THANKS TO CLOUDS AND RAIN...WHILE LOCATIONS WEST OF I-95 WILL AGAIN SOAR ABOVE 95 DEGREES. WEDNESDAY WILL BE MORE UNIFORM AND HOTTER...WITH HIGHS REACHING WELL INTO THE 90S EVERYWHERE...AND MAYBE A SPOT 100 IN THE WARMEST PLACES. LOWS BOTH NIGHTS WILL BE A DEGREE OR 2 EITHER SIDE OF 75. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 300 AM MONDAY...HOT WEATHER THURSDAY AS RIDGING ALOFT PERSISTS ONE MORE DAY WILL TRANSITION QUICKLY ON FRIDAY AS A COLD FRONT CROSSES THE AREA. THIS FRONT LOOKS SURPRISINGLY STRONG FOR EARLY- AUGUST...AND IN ADDITION TO GOOD CONVECTION CHANCES FRIDAY AND SATURDAY...MUCH COOLER TEMPERATURES WILL FOLLOW IN ITS WAKE. THE SUBSEQUENT LONGWAVE TROUGH IS FORECAST TO BE -1 TO -2 SD`S FROM CLIMO...AND BOTH MEX/ECE NUMBERS ARE ALREADY BELOW CLIMO EVEN AS THEY ARE POSITIVELY INFLUENCED BY THE MEAN. THIS SUGGESTS THAT THURSDAY WILL BE HOT...FRIDAY SEASONABLE...AND THEN BELOW NORMAL FOR THE WKND. INHERITED LOOKS GOOD FOR THE WKND WITH MID-TO-UPR 80S AND WILL DROP ONLY SLIGHTLY. BY SUNDAY HOWEVER...DRIER AIR IS FORECAST SO POP WILL RAMP DOWN BEHIND THE BOUNDARY. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... AS OF 06Z...SURGE OF PRECIPITATION MOVING UP AND ALONG THE SE U.S. COAST. FORECAST ISSUE OF THE DAY WILL BE THE SURFACE LOW ACROSS THE NE GULF OF MEXICO MOVING/DRIFTING NE INTO NRN FLORIDA...AND THEN INTO GEORGIA WITHIN THE NEXT 24 HOURS. PWAT AMOUNTS INCREASE TO ABOUT 2.25 INCHES ACROSS MAINLY THE COASTAL AREAS AS PER THE MODEL SOUNDINGS BUT REMAINING LESS THAN 2 INCHES INLAND. MODELS SHOW SHARP DECREASE IN THE PRECIPITATION SHIELD AS YOU MOVE WESTWARD...WITH INTERSTATE 95 ACTING LIKE THE DIVIDING LINE BETWEEN PCPN OR NO PCPN. ANY SHIFT IN THE MODELS JUST 30 MILES EITHER WAY CAN HAVE A SIGNIFICANT IMPACT ON THE FORECAST. WILL MAINLY HEDGE WITH MVFR PERHAPS IFR ALONG THE COASTAL TERMINALS DURING THE DAY WITH PERIODS OF RAIN SOME OF WHICH MIGHT BE HEAVY AND VFR/MVFR INLAND WITH SOME SHWRS. MOST OF THE ACTIVITY WILL BE ALONG THE COAST. CONFIDENCE IN FORECAST CONDITIONS ARE LOW AS MODELS DIFFER WITH SPEED AND STRENGTH OF LOW COMING OUT OF THE GOM. EXTENDED OUTLOOK...PREDOMINANTLY VFR THROUGH THE PERIOD WITH A SLIGHT CHANCE AFTERNOON SHRA/TSRA. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM SUNDAY...LATEST OBS SHOW SOUTHERLY WINDS AT AROUND 15 KTS WITH 4 FT SEAS. THIS FITS IN WELL WITH THE LATEST FORECAST WHICH PROJECTS A GRADUAL TIGHTENING OF THE GRADIENT OVERNIGHT...WITH SEAS INCREASING UP TO 5 FT. PREVIOUS DISCUSSION FROM THIS AFTERNOON FOLLOWS: THE PRESSURE GRADIENT WILL INCREASE SLIGHTLY THROUGH THE LATER AFTERNOON AND OVERNIGHT HOURS. THE OVERALL PATTERN IS STILL RELATIVELY WEAK HOWEVER (41013 IS CURRENTLY REPORTING CALM WINDS) AND WINDS WILL LOSE THE SEA BREEZE INFLUENCE OF A SE DIRECTION AND GO MORE SOUTHWEST. SPEEDS SHOULD SETTLE NICELY INTO A 10-15 KNOT RANGE. SEAS WILL INCREASE FROM 2-4 FEET TO 3-5 FEET AFTER 0600 UTC VIA THE SUBTLE INCREASE IN WINDS AND A DECENT SWELL COMPONENT REMAINING IN THE MIX. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 300 AM MONDAY...POSSIBLE SCA CONDITIONS START THE PERIOD AS A LOW PRESSURE WILL BE SLOWLY MOVING ALONG A STATIONARY BOUNDARY DRAPED ALONG THE COAST. ALTHOUGH SOUTHERLY WINDS ARE FORECAST TO REMAIN JUST BELOW SCA THRESHOLDS...UP TO 20 KTS...THE PROLONGED DURATION AND FETCH OF THESE WINDS WILL DRIVE SEAS UP TO 4-6 FT INTO TUESDAY NIGHT. AS THE LOW PULLS AWAY TUESDAY NIGHT WINDS WILL EASE AND SHIFT TO THE W/NW FOR A SHORT TIME INTO WEDNESDAY MORNING...BEFORE BERMUDA HIGH PRESSURE BUILDS BACK TOWARDS THE WATERS AND WINDS RETURN TO THE S/SW AT 10-15 KTS LATE WEDNESDAY. SEAS WILL BE HIGHEST FIRST THING WEDNESDAY AT 3-5 FT THANKS TO THE RESIDUAL SPECTRUM FROM TUESDAY...BEFORE FALLING TO 2-4 FT AT THE END OF THE PERIOD. LONG TERM /THURSDAY THROUGH FRIDAY/... AS OF 300 AM MONDAY...BERMUDA HIGH PRESSURE WILL DOMINATE THE FLOW THURSDAY AND MOST OF FRIDAY...WITH TYPICAL SUMMERTIME 10-15 KT SW WINDS EXPECTED ACROSS THE WATERS. BRIEF INCREASES UP TO 20 KTS ARE POSSIBLE IN THE EVENING AS THE PIEDMONT TROUGH SHARPENS AS WELL. A COLD FRONT WILL APPROACH AT THE END OF THE PERIOD...BUT ANY WIND SHIFT WILL LIKELY HOLD OFF UNTIL BEYOND THE EXTENDED. SEAS WILL BE 2- 4 FT...RISING UP TO 3-5 FT THURSDAY EVENING ON THE SLIGHTLY INCREASED WINDS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR AMZ250- 252. && $$ SYNOPSIS...JDW NEAR TERM...DCH SHORT TERM...JDW LONG TERM...JDW AVIATION...DCH MARINE...DCH/JDW

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