Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 030809
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
408 AM EDT MON AUG 3 2015

.SYNOPSIS...
AN AREA OF LOW PRESSURE NEAR THE BIG BEND OF FL THIS MORNING WILL
TRACK SLOWLY NORTHEAST IN THE VICINITY OF A NEARLY STATIONARY FRONT
OVER THE SOUTHEASTERN US THROUGH TUE NIGHT. WEAK HIGH PRESSURE WILL
OTHERWISE REMAIN SITUATED OVER THE SOUTHERN APPALACHIANS.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 345 AM MONDAY...

MOIST SOUTHERLY FLOW ON THE NE PERIPHERY OF AN AREA OF LOW PRESSURE
NEAR THE BIG BEND OF FL THIS MORNING WILL SUPPORT THE CONTINUED
NORTHWARD DEVELOPMENT/EXPANSION OF AN AREA OF SCATTERED TO BROKEN
MVFR RANGE/LOW CLOUDS INTO CENTRAL AND SOUTHEASTERN NC THIS MORNING.
THE LOW CLOUDS ARE EXPECTED TO LIFT AND SCATTER TO PARTLY TO
OCCASIONALLY MOSTLY CLOUDY OVER THE COASTAL PLAIN...PARTICULARLY THE
SOUTHERN AND CENTRAL HALF...WHILE PARTLY TO MOSTLY SUNNY SKIES ARE
EXPECTED ELSEWHERE. RICHER LOW LEVEL MOISTURE ALONG AND EAST OF A
QUASI-STATIONARY FRONT OVER THE EASTERN PART OF THE STATE...
CHARACTERIZED BY SURFACE DEWPOINT TEMPERATURES IN THE LOWER
70S...WILL ALSO SUPPORT SCATTERED SHOWERS AND STORMS OVER THE FAR
EASTERN SANDHILLS AND SOUTHERN AN CENTRAL COASTAL PLAIN FROM LATE
MORNING ONWARD. HIGH TEMPERATURES IN THE UPPER 80S TO MIDDLE
90S...COOLEST FROM CTZ TO GSB WHERE CLOUDS WILL BE MOST
PREVALENT...AND WARMEST OVER THE SOUTHERN PIEDMONT AND SANDHILLS.

GIVEN LITTLE CHANGE IN THE OVERALL PATTERN...ASIDE FROM THE SLOW
APPROACH OF THE AREA OF LOW PRESSURE FROM FL...LOW CLOUDS ARE APT TO
REDEVELOP AMIDST CONTINUED MOIST SOUTHERLY FLOW TONIGHT...WITH A
CONTINUED CHANCE OF SHOWERS AND STORMS OVER THE FAR EASTERN AND
SOUTHEASTERN FRINGES OF THE RAH COASTAL PLAIN. LOWS 68 TO 74.

&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 400 AM MONDAY...

CENTRAL NC WILL REMAIN LARGELY SANDWICHED BETWEEN THE NEARLY
STATIONARY FRONTAL ZONE OVER THE EASTERN CAROLINAS AND NORTHEAST
DRIFTING AREA OF LOW PRESSURE ACROSS THE COASTAL CAROLINAS...AND A
COLD FRONT FORECAST TO APPROACH FROM THE NORTHWEST AND STALL NEAR
THE NC/VA STATE BORDER BY WED MORNING. THE RESULT WILL BE A
CONTINUED CHANCE OF SHOWERS AND STORMS OVER THE COASTAL PLAIN...IN
CLOSEST PROXIMITY TO THE STATIONARY FRONT. AND ELSEWHERE...THERE
WILL BE A SLIGHT CHANCE OF A LATE AFTERNOON AND EVENING STORM FROM
ACTIVITY THAT COULD EITHER DEVELOP IN-SITU INVOF A PIEDMONT SURFACE
TROUGH AND/OR THAT WILL INITIATE UPSTREAM OVER THE MOUNTAINS AND
INVOF THE AFOREMENTIONED FRONT...WHICH WOULD THEN PROPAGATE AWAY
FROM THOSE FORCING MECHANISMS AND INTO THE NC PIEDMONT. FORECAST LOW
LEVEL THICKNESS VALUES RISE ABOUT 5-10 METERS PER A CONSENSUS OF
MODEL GUIDANCE...SUPPORTIVE OF LOWER TO MIDDLE 90S AREA-WIDE...WITH
A FEW 97-98 DEGREE READINGS POSSIBLE FROM AFP TO FAY. LOWS GENERALLY
70 TO 75.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 240 AM MONDAY...

REALLY NO CHANGES TO THE UPPER LEVEL PATTERN DURING THE LONG TERM
WHICH WILL FEATURE AN UPPER LEVEL RIDGE OVER THE SOUTHWESTERN CONUS
AND A WEAK UPPER TROUGH OVER THE EAST COAST. SEVERAL SHORT WAVES
WILL MAKE THEIR WAY THROUGH THE UPPER LEVEL FLOW DURING THIS PERIOD
AND THERE IS QUITE A BIT OF UNCERTAINTY REMAINING IN THE FORECAST
WITH REGARD TO TIMING OF THESE FEATURES. PRIOR SIMULATIONS HAD
SHOWED THE FIRST IMPULSE MOVING THROUGH ON THURSDAY...BUT THIS
FEATURE ALTHOUGH STILL THERE...HAS WEAKENED CONSIDERABLY AND MAY BE
OF LITTLE CONSEQUENCE OTHER THAN A FEW SHOWERS BY THE TIME IT MOVES
ACROSS THE AREA THURSDAY MORNING INTO EARLY AFTERNOON.

IT APPEARS MODELS ARE HONING IN ON A SHORTWAVE ON EARLY FRIDAY TO BE
THE MOST VIGOROUS OF THE PERIOD. WHILE THIS FEATURE REMAINS
DISORGANIZED IN THE GFS SIMULATION...THE ECMWF MODEL IS WRAPPING IT
UP INTO QUITE A STRONG LOW THAT PASSES ACROSS VIRGINIA BEFORE
EXITING OFF OF THE DELMARVA COAST. DIURNAL TIMING LOOKS A LITTLE OFF
WITH THE BEST SHEAR ARRIVING PRIOR TO THE BEST INSTABILITY...WHICH
SHOULD HELP CUT BACK SEVERE CHANCES. THAT BEING SAID...TIMING HAS
CHANGED SO MUCH WITH THE SUCCESSIVE RUNS OF THE MODELS THAT TO THINK
THIS RUN IS ACCURATE WITHIN 6-12 HOURS WOULD BE NAIVE SO WE WILL
HAVE TO WAIT AND SEE HOW THE TIMING LINES UP IN LATER RUNS. IF
SUCCESSIVE RUNS COME IN A LITTLE LATER AND THE ECMWF IS RIGHT WITH
THE INTENSITY...THEN SEVERE CHANCES COULD INCREASE QUITE A BIT FOR
FRIDAY AFTERNOON EVENING. AT THIS POINT WILL JUST CARRY CHANCE OF
THUNDER FRIDAY MORNING INTO THE AFTERNOON HOURS.

FOR THE WEEKEND...BOTH DAYS SHOULD BE RELATIVELY DRY COMPARED TO
FRIDAY...BUT SOME LINGERING WEAK ENERGY IN THE NORTHERN STREAM COULD
CAUSE SOME SHOWERS...ESPECIALLY IN THE NW PIEDMONT AND VA BORDER
COUNTIES. ON SATURDAY NIGHT INTO SUNDAY...THE ECMWF DEVELOPS THE
ACTIVITY NOW IN THE NORTHEAST GULF OF MEXICO AS IT EMERGES OF OF THE
NE FLORIDA COAST. THIS SURFACE LOW TRAVELS UP THE CAROLINA COAST AND
COULD BE OFF OF THE OUTER BANKS BY SUNDAY NIGHT BUT AT THIS TIME
APPEARS SHOWER ACTIVITY SHOULD BE TOO FAR EAST TO THREATEN ANY OF
THE EASTERN COUNTIES.

TEMPERATURES WILL BEGIN THIS PERIOD IN THE MID 90S BUT CONTINUE TO
FALL INTO THE MID 80S BY THE END OF THE WEEKEND. LOWS WILL ALSO DROP
OFF FROM THE LOW TO MID 70S TO THE MID TO UPPER 60S BY THE END OF
THE PERIOD.

&&

.AVIATION /06Z MONDAY THROUGH THURSDAY/...
AS OF 220 AM MONDAY...

MOIST SOUTHERLY FLOW ON THE NE PERIPHERY OF AN AREA OF LOW PRESSURE
NEAR THE BIG BEND OF FL THIS MORNING WILL SUPPORT THE CONTINUED
NORTHWARD DEVELOPMENT/EXPANSION OF AN AREA OF SCATTERED TO BROKEN
MVFR RANGE CLOUDS INTO CENTRAL NC THIS MORNING...WITH THE RELATIVE
HIGHEST PROBABILITY OF OCCURRENCE AND LONGEST DURATION AT
FAY...WHERE FLEETING MVFR CEILINGS HAVE ALREADY BEEN REPORTED IN THE
PAST COUPLE OF HOURS. THE LOW CLOUDS ARE EXPECTED TO LIFT AND
SCATTER TO VFR BETWEEN 13-15Z...THOUGH PERIODS OF CUMULUS CEILINGS
BETWEEN 3500-6000 FT ARE APT CONTINUE AT EASTERN TAF SITES
THROUGHOUT THE DAY. THE INCREASED CLOUD COVER AT EASTERN SITES WILL
ALSO SUPPORT A RELATIVE HIGHER PROBABILITY OF A SHOWER OR STORM FROM
LATE MORNING ONWARD.

CONTINUED MOIST SOUTHERLY LOW LEVEL AROUND THE AFOREMENTIONED LOW
PRESSURE AREA OVER FL WILL RESULT IN A MEDIUM CHANCE...40-50
PERCENT...OF THE REDEVELOPMENT OF IFR-MVFR CEILINGS THROUGHOUT
CENTRAL NC TONIGHT.

ASIDE FROM AN ISOLATED TO WIDELY SCATTERED AFTERNOON AND EVENING
STORM...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH MID-WEEK. A
FRONT WILL SETTLE INTO NC BY THE END OF THE WEEK...AT WHICH TIME THE
PROBABILITY OF SHOWERS AND STORMS...AND SUB-VFR CONDITIONS...ARE
EXPECTED TO INCREASE.

&&

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

&&

$$

SYNOPSIS...26
NEAR TERM...26
SHORT TERM...26
LONG TERM...ELLIS
AVIATION...26



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