Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 070630
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
230 AM EDT THU MAY 7 2015

.SYNOPSIS...THE LOW PRESSURE SYSTEM OFF THE SOUTHEAST COAST MAY
EVOLVE INTO A SUBTROPICAL OR TROPICAL CYCLONE OVER THE NEXT 12 TO 24
HOURS AS IT DRIFTS SLOWLY NORTHWARD AND THEN NORTHWESTWARD TOWARDS
THE CAROLINAS THROUGH THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM THURSDAY...

GIVEN WEAK STEERING FLOW ALONG THE SOUTHERN AND EASTERN PERIPHERY OF
CONTINUED RIDGING ALOFT THAT EXTENDS FROM THE NORTHWEST GOM NEWD
INTO THE NORTHEAST US...THE DEEPENING LOW OFF THE SOUTHERN COAST OF
GEORGIA WILL INITIALLY DRIFT NORTHWARD TODAY...WITH INDICATIONS OF A
SLIGHTLY MORE NORTHWESTWARD JOG OVERNIGHT AND THROUGH THE DAY ON
FRIDAY.  WHILE SOME OF THE FIRST OUTER RAIN BANDS ARE CURRENTLY
MOVING ASHORE THE SC/NC COASTS...SENSIBLE WX IMPACTS TODAY AND
TONIGHT STILL LOOK VERY MINIMAL WITH MOST OF THE FORECAST STILL
UNDER THE INFLUENCE OF  SUBSIDENCE ALOFT AND DRY AIR SURFACE RIDGE
EXTENDING FROM THE DELMARVA COAST SOUTHWESTWARD DOWN THE EASTERN
SLOPES OF THE SOUTHERN APPALACHIANS. THE EXCEPTION MAY BE ACROSS THE
FAR SE ZONES IN PROXIMITY TO THE STRENGTHENING ONSHORE FLOW/MOISTURE
CONVERGENCE.  HAVE KEPT SLIGHT TO SMALL CHANCE POPS ACROSS THE
SOUTHERN COASTAL PLAIN AND SANDHILL COUNTIES.

ASSOCIATED THICKENING CLOUDS SHIELD WILL TEMPER DAYTIME HEATING IN
THESE AREAS AS WELL...WITH HIGHS RANGING FROM MID TO UPPER 70S
ACROSS THE SOUTHEAST TO LOWER 80S OVER THE WESTERN-CENTRAL PIEDMONT.
BROKEN/OVERCAST SKIES COUPLED WITH MORE HUMID AIR BEING DRAWN INTO
THE AREA OVERNIGHT WILL RESULT IN MILDER OVERNIGHT LOWS IN THE UPPER
50S TO LOWER 60S.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 230 AM THURSDAY...

THE SYSTEM IS EXPECTED TO LARGELY MEANDER SOUTH OF CAPE FEAR FRIDAY-
FRIDAY NIGHT. ONCE AGAIN...OUTSIDE OF THE SE ZONES...IMPACTS ARE
EXPECTED TO BE FAIRLY MINIMAL. HOWEVER...ISOLATED CONVECTION COULD
BE MORE APT TO DEVELOP WELL INLAND OWING TO RISING HUMIDITY
LEVELS/DEWPOINTS AND RESULTANT WEAK TO MODERATE DESTABILIZATION
FRIDAY AFTERNOON. NO SEVERE STORMS ARE EXPECTED AT THIS TIME GIVEN
WEAK FIELD AND WEAK FORCING.

WITH NO CHANGE IN AIRMASS...HIGHS AGAIN IN THE UPPER 70S TO LOWER
80S...BUT ULTIMATELY DEPENDENT BY CLOUDS AND CONVECTIVE COVERAGE.
LOWS 60-65.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 300 PM WEDNESDAY...

MUCH OF THE LONG TERM WILL BE DOMINATED BY THE SUBTROPICAL OR
TROPICAL SYSTEM THAT IS EXPECTED TO FORM OFF OF THE SOUTH CAROLINA
COAST. THIS SYSTEM WILL MEANDER ALONG THE SC AND NC COASTLINES
THROUGH AT LEAST MONDAY AND POSSIBLY INTO TUESDAY. MODEL FORECASTS
DIVERGE SIGNIFICANTLY BY SUNDAY AND CONFIDENCE IN THE LOCATION AND
INTENSITY OF THE SYSTEM BECOMES LOWER. NEAR THE END OF THE PERIOD A
COLD FRONT APPROACHES FROM THE WEST AND HELPS TO USHER THE TROPICAL
SYSTEM OUT TO SEA.

AS BEST AS DETAILS CAN BE IRONED OUT RIGHT NOW EXPECT THE MOST RAIN
TO BE IN THE SOUTH EASTERN COUNTIES BUT AT THIS TIME MOISTURE DOES
NOT LOOK HIGH ENOUGH TO PRODUCE SIGNIFICANT RAINFALL THAT WOULD
RESULT IN ANY KIND OF FLOODING. A WESTWARD SHIFT IN TRACK WOULD
RAISE THE POTENTIAL FOR SIGNIFICANT RAIN IN THE EASTERN COUNTIES
OVER THE WEEKEND AND INTO EARLY NEXT WEEK. FORECAST SOUNDINGS ARE
DEPICTING INSTABILITY DURING THE AFTERNOON HOURS EACH
AFTERNOON/EVENING BUT THE OVERNIGHT/MORNING HOURS SHOULD BE MOSTLY
CHARACTERIZED BY CONVECTIVE SHOWERS. SEVERE POTENTIAL LOOKS MINIMAL
AT THIS TIME AND WIND SHEAR VALUES ARE LOW ENOUGH THAT THE THREAT
FOR TROPICAL TORNADOES ALSO LOOKS MINIMAL AT THIS TIME. IN GENERAL
WINDS WILL BE OUT OF THE NORTHEAST AT AROUND 10 KTS GUSTING TO 15-20
KTS.

ON MONDAY NIGHT A COLD FRONT IS EXPECTED TO MOVE THROUGH FROM THE
WEST WITH SOME SHOWERS AND THUNDERSTORMS POSSIBLE WITH GOOD
INSTABILITY BUT ONLY ABOUT 20 KTS OF SHEAR SUGGESTIVE OF
MULTICELLULAR CONVECTION AT BEST. AFTER FRONTAL PASSAGE...WINDS WILL
BECOME NORTHWESTERLY AND DEWPOINTS ARE EXPECTED TO DROP BACK INTO
THE 50S. UNTIL THEN EXPECT HIGHS IN THE 80S WITH LOWS IN THE LOW TO
MID 60S. A RETURN TO DRY WEATHER AND SLIGHTLY COOLER TEMPS IS
EXPECTED ON WEDNESDAY.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 125 AM THURSDAY...

24-HOUR TAF PERIOD:
VFR CONDITIONS ARE EXPECTED TO HOLD OVERNIGHT AND THROUGH THE DAYLIGHT
HOURS WITH MID/HIGH CLOUDS GRADUALLY THICKENING AND LOWERING BY THE
AFTERNOON. LIGHT AND VARIABLE OVERNIGHT WILL BECOME NELY BY DAYBREAK
OWING TO THE SLOW APPROACH OF THE OFFSHORE CYCLONE...INCREASING
THROUGHOUT TH DAY WITH GUSTS BETWEEN 15 TO 20KTS ACROSS CENTRAL
AND EASTERN TERMINALS. ANY SHOWERS SHOULD REMAIN CONFINED TO KFAY.
ASSOCIATED CYCLONIC ONSHORE FLOW WILL BEGIN TO ADVECT LOW-LEVEL
MARITIME MOISTURE INTO THE AREA LATE IN THE PERIOD(BETWEEN 00 TO
06Z)...WITH SUB-VFR CEILINGS SPREADING EAST TO WEST THROUGH DAYBREAK
FRIDAY.

LOOKING AHEAD: THE EVENTUAL SUBTROPICAL OR TROPICAL LOW WILL DRIFT
SLOWLY NORTHWARD ALONG THE SOUTHEAST U.S. COAST...STALLING AND
MEANDERING SOMEWHERE IN THE VICINITY OF SOUTH CAROLINA OR NORTH
CAROLINA LATE IN THE WEEK AND THROUGH THE WEEKEND. ALTHOUGH MODEL
AGREEMENT CONTINUES TO GET BETTER WITH THIS SYSTEM... THERE IS STILL
A LOT OF UNCERTAINTY WITH RESPECT TO THE PATH OF THIS SYSTEM...BUT
REGARDLESS...THIS SYSTEM COULD RESULT IN SOME ADVERSE AVIATION
IMPACTS IN WIDESPREAD SHOWERS AND THUNDERSTORMS...AND COULD PERSIST
THROUGH SUNDAY...ESPECIALLY ACROSS SOUTHERN AND EASTERN NC.
ADDITIONALLY...ENHANCED EASTERLY ONSHORE FLOW FROM THIS SYSTEM COULD
BRING AN INCREASE THREAT FOR MORNING STRATUS/FOG.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...CBL
NEAR TERM...CBL
SHORT TERM...CBL
LONG TERM...ELLIS
AVIATION...CBL


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