Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 191533
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1133 AM EDT FRI SEP 19 2014

.SYNOPSIS...
A NORTHEASTERLY SURGE WILL PERSIST INTO SATURDAY AS HIGH PRESSURE
WEDGES ACROSS THE CAROLINAS. LOW PRESSURE WILL DEVELOP OFF THE EAST
COAST OF FLORIDA AND THEN MOVE NORTH...PASSING OFF THE CAROLINA
COAST SATURDAY NIGHT AND SUNDAY. THE LOW IS EXPECTED TO REMAIN FAR
ENOUGH OFFSHORE SUCH THAT ITS IMPACTS WILL BE LIMITED. A COLD
FRONT WILL MOVE ACROSS THE AREA MONDAY. HIGH PRESSURE WILL BUILD
BACK DOWN THE COAST ON TUESDAY...BRINGING A COOL AND DRY NORTHEAST
FLOW.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1100 AM FRIDAY...STRONG HIGH PRESSURE CENTERED ACROSS NEW
ENGLAND WILL BEGIN TO WEDGE STRONGLY ACROSS THE EASTERN CAROLINAS
TODAY AND THEN PERSIST INTO TONIGHT. MEANTIME...AN INVERTED TROUGH
POKING UP THE SOUTHEAST COAST FROM OFFSHORE OF FLORIDA WILL
SHARPEN. LOW LEVEL WINDS WILL CONTINUE TO GUST IN THE NEIGHBORHOOD
OF 20 TO 25 MPH...HIGHEST AT THE COAST AS A RATHER TIGHT PRESSURE
GRADIENT WILL EXIST BETWEEN THE OFFSHORE TROUGH AND THE STRONG
AREA OF HIGH PRESSURE.

AS THE ONSHORE FLOW INCREASES THROUGH 25 KFT...WOULD EXPECT THE
COLUMN TO MOISTEN...BUT MODELS CONTINUE TO SHOW THIS TO BE A VERY
GRADUAL UNDERTAKING.

AS FAR AS CONVECTION TODAY...WE SHOULD AGAIN SEE SOME ISOLATED
DEVELOPMENT ALONG THE RESULTANT SEABREEZE...ACROSS THE CAPE FEAR
AREA. A LARGE AREA OF SHOWERS AND THUNDERSTORMS REMAINS OFFSHORE
IN ASSOCIATION WITH THE INVERTED TROUGH. SOME OF THIS ACTIVITY
SHOULD MIGRATE ONSHORE GIVEN THE PREVAILING FLOW. THE RISK FOR
THIS WILL BE HIGHEST ACROSS THE GRAND STAND AND WINYAH BAY AREA
AND PERHAPS ALONG THE SOUTH SANTEE RIVER.

ALTHOUGH IT IS SLIGHTLY COOLER ALOFT...THE HEATING AT THE SURFACE
IS LOWER AND THUS THE INSTABILITY IS LESS TODAY THAN IT WAS EVEN
ON THU. THEREFORE...THUNDERSTORMS SHOULD BE FEW...BUT AGAIN THE
RISK WILL BE HIGHEST ALONG THE SOUTH CAROLINA COAST.

GIVEN THE INVERTED TROUGH WILL BE SHARPENING AND EXPANDING
NORTHWARD...EXPECT SHOWERS WILL BECOME MORE NUMEROUS FROM SOUTH TO
NORTH TONIGHT. WILL SHOW POPS INCREASING ALONG AND EAST OF A LINE
FROM CKI TO EYF...HIGHEST ALONG THE COAST. WILL INCLUDE
THUNDERSTORMS ALONG/NEAR THE COAST AS WELL GIVEN THE DEEPENING
MOISTURE SUPPLY.

HIGHS TODAY WILL BE IN THE LOWER 80S WITH LOWS TONIGHT IN THE
60S.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...HIGH PRESSURE WILL BUILD DOWN THE COAST SAT
WHILE WEAK TROUGHING ALOFT CONTINUES. SURFACE LOW WILL START TO TAKE
SHAPE OFF THE EAST COAST OF FL. THIS LOW DEVELOPS ALONG THE REMAINS
OF A STALLED SURFACE BOUNDARY SO INITIALLY IT WILL NOT BE TROPICAL
IN NATURE BUT AS IT LIFTS NORTH-NORTHEAST IT MAY ACQUIRE SOME
TROPICAL CHARACTERISTICS. NHC CONTINUES TO ADVERTISE A 20% CHANCE OF
TROPICAL DEVELOPMENT THROUGH 5 DAYS...BUT EVEN IF THIS FEATURE
DEVELOPS INTO A FULL BLOWN TROPICAL SYSTEM IT WILL HAVE A LIMITED
AMOUNT OF TIME TO STRENGTHEN AND STEERING FLOW WOULD KEEP IT OFF THE
COAST.

ULTIMATE PATH OF THE LOW IS STILL IN QUESTION...WITH HOW CLOSE IT
PASSES OFF THE COAST THE MAIN CONCERN. DO NOT THINK ANY SIGNIFICANT
WINDS WILL BE REALIZED BUT IT COULD MAKE FOR A CLOUDY/SOGGY
SAT...ESPECIALLY ALONG THE IMMEDIATE COAST. OCCASIONAL GUSTS TO 20
MPH ALONG THE COAST ARE A POSSIBILITY. INLAND THERE WILL BE LESS OF
A PRECIP THREAT THOUGH ENHANCED NORTHEAST FLOW BETWEEN THE SURFACE
HIGH AND THE DEVELOPING LOW WOULD LIKELY MAINTAIN SOME LOWER CLOUDS
AND THE PINCH GRADIENT WILL CREATE BREEZY CONDITIONS. WILL CARRY LOW
CHC TO SLIGHT CHC POP ALONG THE COAST SAT INTO SAT NIGHT AND DRY
INLAND. NORTHEAST FLOW...CLOUDS...AND PRECIP WILL KEEP HIGHS BELOW
CLIMO BUT LINGERING CLOUD COVER AND MOISTURE OVERNIGHT WILL HOLD
LOWS ABOVE CLIMO.

EXITING SURFACE LOW AND MID LEVEL TROUGH IN PLACE LEADS TO
DEVELOPMENT OF DEEP WEST TO NORTHWEST FLOW SUN...DRYING THE REGION
OUT. PRECIPITABLE WATERS DROP ABOUT AN INCH SAT INTO SUN...FALLING
FROM AROUND 1.7 TO AROUND 0.7. THE RESULT WILL BE BEAUTIFUL DAY WITH
ABUNDANT SUNSHINE AND HIGHS IN THE MID 80S. DEVELOPMENT OF RETURN
FLOW AHEAD OF ADVANCING COLD FRONT WILL HELP KEEP LOWS ABOVE TO WELL
ABOVE CLIMO SUN NIGHT THOUGH SKIES SHOULD BE MOSTLY FREE OF CLOUDS.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...MID LEVEL TROUGH DROPPING SOUTH FROM THE WESTERN
GREAT LAKES WILL PUSH A COLD FRONT ACROSS THE AREA MON. WHERE
PREVIOUS MEDIUM RANGE GUIDANCE HAD A DECENT AMOUNT OF MID LEVEL
MOISTURE THE LAST FEW RUNS HAVE SHOWN A STEADY DECREASE IN MOISTURE
ALOFT AND QPF. AT THIS POINT EVEN WITH IDEAL TIMING DURING PEAK
HEATING THINK CONVECTION IS GOING TO BE SPOTTY IN NATURE AND HAVE NO
PLANS TO CHANGE INHERITED SLIGHT CHC POP.

FRONT ENDS UP STALLED OFF THE COAST TUE WITH MODIFIED HIGH BUILDING
IN FROM THE PLAINS. MID LEVEL PATTERN OVER THE SOUTHEAST TRANSITIONS
TO PROGRESSIVE TUE INTO WED AS THE 5H TROUGH OVER SOUTHEAST CANADA
LIFTS NORTHEAST. MOISTURE ALONG THE STALLED FRONT MAY LEAD TO
COASTAL CLOUDS AND LIGHT PRECIP DURING THE DAY.

SOLUTIONS FOR MID TO LATE WEEK DIVERGE WITH SOME OF THE GUIDANCE
SHOWING A COLD FRONT PUSHING SOUTH ON WED AS REINFORCING HIGH BUILDS
IN. THIS WOULD KEEP THE REGION COOL AND DRY THROUGH THE END OF THE
PERIOD. THE OTHER SOLUTION INVOLVES A COASTAL TROUGH WITH A WEAKER
REINFORCING SURFACE HIGH. THE TROUGH AND ASSOCIATED MOISTURE ARE
MUCH CLOSER TO THE COAST WITH CLOUDS/PRECIP OVER MUCH OF THE
SOUTHEAST. ONLY PLAN MINIMAL CHANGES TO INHERITED FORECAST UNTIL MID
TO LATE WEEK DETAILS BECOME A LITTLE CLEARER.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...STRONG WEDGE WILL CONTINUE THROUGH THE FORECAST
PERIOD. GRADIENT WILL BE QUITE STRONG...WITH EAST NORTHEAST WINDS
ALONG THE COAST GUSTING TO 20 KT. THERE WILL BE SHOWERS ALONG THE
PERIPHERY OF THE WEDGE...AND THERE IS A POSSIBILITY OF CONVECTION
ALONG THE EXTREME WESTERN PORTION OF THE CWA...AS WELL AS THE
COAST. COVERAGE WILL BE QUITE LIMITED HOWEVER. WINDS WILL BE
LIGHTER TONIGHT...BUT WILL STAY ABOVE 7-8 KT MOST OF THE NIGHT. A
NOCTURNAL ONSHORE SHOWER IS POSSIBLE AT THE MYRTLES NEAR THE END
OF THE FORECAST PERIOD.

EXTENDED OUTLOOK...CHANCE OF SHOWERS ALONG THE COAST SAT. GUSTY
NORTHEAST WINDS SAT WILL BECOME NORTHWEST ON SUN AS LOW PRESSURE
WELL OFFSHORE MOVES UP THE EAST COAST. VFR ON MON/TUE.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1100 AM FRIDAY...STRONG HIGH PRESSURE CENTERED ACROSS NEW
ENGLAND WILL BEGIN TO WEDGE STRONGLY ACROSS THE EASTERN CAROLINAS
TODAY AND THEN PERSIST INTO TONIGHT. MEANTIME...AN INVERTED TROUGH
POKING UP THE SOUTHEAST COAST FROM OFFSHORE OF FLORIDA WILL
SHARPEN AS IT EXPANDS NORTHWARD. THIS WILL KEEP A RATHER TIGHT
PRESSURE GRADIENT IN PLACE. WINDS ARE ALREADY GUSTING NEAR 25 KT
AND SEAS...EVEN NEAR SHORE...WERE UP TO 5 FT...SO HAVE RAISED A
SMALL CRAFT ADVISORY FOR ALL WATERS THROUGH THE REMAINDER OF
TODAY AND INTO SAT MORNING. SUSTAINED NORTHEAST TO EAST WINDS WILL
BE UP TO AROUND 20 KT. SEAS WILL BE UP TO 5 TO 7 FT.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 300 AM FRIDAY...CONFIDENCE IS HIGH IN HIGH PRESSURE
BUILDING DOWN THE COAST SAT AS WEAK LOW PRESSURE DEVELOPS OFF THE
EAST FL COAST AND STARTS MOVING NORTH-NORTHEAST. HOWEVER...HAVE
LOW CONFIDENCE WITH RESPECT TO THE STRENGTH AND PATH THE LOW
TAKES. WHILE IT COULD ACQUIRE SOME TROPICAL CHARACTERISTICS AS IT
LIFTS NORTH CURRENT CONSENSUS IS THE LOW WILL REMAIN EAST OF THE
WATERS. PINCHED GRADIENT BETWEEN THE HIGH AND THE PASSING LOW WILL
CAUSE NORTHEAST FLOW IN THE 15 TO 20 KT RANGE SAT INTO SAT NIGHT.

WINDS BACK TO NORTHWEST AND THEN WEST-SOUTHWEST AS THE LOW EXITS OFF
TO THE NORTH ON SUN. GRADIENT WEAKENS AS THE LOW DEPARTS WITH WIND
SPEEDS DROPPING TO 10 TO 15 KT SUN AND UNDER 10 KT SUN NIGHT. 3 TO 5
FT SEAS SAT WILL SUBSIDE TO 2 TO 3 FT BY SUN AFTERNOON AS WINDS
BECOME OFFSHORE AND WEAKEN. IF THE LOW ENDS UP A LITTLE CLOSER TO
THE COAST LATE SAT SCA CONDITIONS MAY DEVELOP.

LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 300 AM THURSDAY...SOUTHWEST FLOW OVER THE WATERS MON WILL BECOME
OFFSHORE MON NIGHT IN THE WAKE OF AN EXITING COLD FRONT. AHEAD OF
AND IMMEDIATELY BEHIND THE FRONT WINDS WILL BE AROUND 10 KT. WINDS
VEER TO NORTHEAST LATE MON NIGHT THEN INCREASE TO 15 TO 20 KT TUE
AND TUE NIGHT. SEAS 2 TO 3 FT MON INTO TUE WILL BUILD TO 3 TO 5 BY
THE END OF THE PERIOD. HEADLINES MAY BE REQUIRED LATE IN THE PERIOD
DEPENDING ON THE STRENGTH AND DURATION OF THE SURGE.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT SATURDAY FOR AMZ250-252-
     254-256.

&&

$$
NEAR TERM...RJD
SHORT TERM...III
LONG TERM...III
AVIATION...DL




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