Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 031055
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
655 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 640 AM MONDAY...LATEST MSAS INDICATES THE SFC BOUNDARY
REMAINS STALLED JUST INLAND FROM THE COAST. THE FA REMAINS
SOMEWHAT SANDWICHED BETWEEN THE ATLANTIC MARINE TROPICAL AIRMASS
AND A CONTINENTAL DRY AIRMASS RELATIVELY SPEAKING. A STREAM OF LOW
TO MID LEVEL MOISTURE FROM THE TROPICS EXTENDS OVERHEAD JUST EAST
AND SOUTH OF THE STATIONARY FRONT THAT LIES JUST INLAND FROM THE
COAST. AT THE MOMENT...A WEAK SFC LOW IS EXITING TO THE NE OF THE
FA TAKING WITH IT THE MAJORITY OF THIS MORNINGS PCPN. AS THE DAY
PROGRESSES...THE S/W TROF ALOFT AND ASSOCIATED SFC LOW WILL TRACK
NE ACROSS NORTHERN FL AND INTO SOUTHERN GA LATER THIS EVENING...
AND SOUTHERN SC BY DAYBREAK TUE. DYNAMICS FROM THESE FEATURES WILL
INTERACT WITH THE STREAM OF MOISTURE EXHIBITING PWS GREATER THAN 2
INCHES...AND PRODUCE MAINLY HEAVY RAIN PRODUCING SHOWERS AND
THUNDERSTORMS. BEST PCPN COVERAGE AND HIEST POPS THRU TONIGHT WILL
REMAIN CONCENTRATED ALONG THE IMMEDIATE COAST. WILL EXHIBIT A
RATHER SHARP DECREASING TREND TO THE POPS AS 1 MOVES INLAND FROM
THE COAST. BY THE TIME 1 REACHES THE I-95 CORRIDOR... POPS WILL
GENERALLY BE ISOLATED TO LOW CHANCE CATEGORY. AS FOR TEMPS...CUT A
FEW DEGREES OFF TODAYS MAX TEMPS FROM THE PREVIOUS UPDATE. THIS
DUE TO ONGOING PCPN AND MORE WIDESPREAD AND OPAQUE CLOUDINESS.

&&

.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 /12Z 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.
REMAINS
EXTENDED OUTLOOK...PREDOMINANTLY VFR THROUGH THE PERIOD WITH A
SLIGHT CHANCE AFTERNOON SHRA/TSRA.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM MONDAY...HOISTED A TEMPORARY SCA FOR THE ILM NC
WATERS TODAY AND A SCEC FOR THE ILM SC WATERS...BOTH THRU 6 PM.
ACTIVE SOUTHERLY WINDS OVERNIGHT PUSHED SIGNIFICANT SEAS TO 4 TO 7
FT ACROSS THE AREA WATERS NORTH OF LITTLE RIVER INLET TO SURF
CITY...MAINLY CONCENTRATED IN THE VICINITY OF CAPE FEAR PER LATEST
BUOY READINGS FROM 41013 AND 41108. THIS WILL BE TEMPORARY AS THE
S/W TROF ALOFT PUSHES NE OF THE AREA WATERS THIS MORNING ALLOWING
THE SFC PG TO RELAX-SOME. WOULD NOT BE SURPRISED TO SEE THIS SCA
DOWNGRADED BY NOON. HOWEVER...INSTEAD OF PLAYING THE YO-YO
GAME...MAY ACTUALLY WANT TO KEEP BOTH HOISTED IN ANTICIPATION OF
THE NEXT OR MAIN SFC LOW AND ASSOCIATED DYNAMICS ALOFT...APPROACH
THE FA FROM THE SW. THIS WILL LIKELY RE-TIGHTEN THE SFC PG
YIELDING 15 KT TO 25 KT SUSTAINED WIND SPEEDS AND PRODUCE A SFC
PRESSURE PATTERN YIELDING MAINLY SSE-SW WIND DIRECTIONS. HEALTHY
SIGNIFICANT SEAS WILL BE COMPRISED MAINLY OF A SOUTHERLY WIND WAVE
AT 6 TO 7 SECOND PERIODS...AND A 1 TO 2 FOOT SE-SSE 10-11 SECOND
PERIOD GROUND SWELL.

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/MAC



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