Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 031421
AFDRAH

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

.SYNOPSIS... A STATIONARY FRONT WILL CONTINUE TO EXTEND THROUGH
CENTRAL NORTH CAROLINA... FROM THE SANDHILLS THROUGH THE NORTHERN
OUTER BANKS... THROUGH MIDWEEK. A COLD FRONT APPROACHING FROM THE
NORTHWEST WILL STALL NEAR THE NORTH CAROLINA VIRGINIA BORDER EARLY
WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 AM MONDAY...

CURRENT FORECAST IS IN GOOD SHAPE. LATEST SURFACE ANALYSIS SHOWS THE
DIFFUSE FRONTAL ZONE STILL BISECTING CENTRAL NC... WITH THE NOTABLY
MORE SOUPY AIR TO ITS SW... AS NOTED BY BLENDED TPW IMAGERY SHOWING
BELOW NORMAL PW OVER ALL BUT THE SE CWA. THE PATCHY STRATUS ACROSS
THE ERN PIEDMONT/SANDHILLS/COASTAL PLAIN THIS MORNING IS GRADUALLY
LIFTING AND BREAKING UP... AND ITS DISSIPATION SHOULD ALLOW FOR
DECENT HEATING OVER MUCH OF THE CWA... UNTIL CUMULUS FORMATION EARLY
THIS AFTERNOON. THE EXIT OF ONE LOOSELY ORGANIZED BATCH OF
SHOWERS/STORMS MOVING NE OVER AND OFF THE SRN OUTER BANKS WILL LEAD
TO A RELATIVE LULL IN POPS BUT THIS SHOULD BE QUICKLY SUPPLANTED BY
ANOTHER WEAK WAVE MOVING E THEN NE THROUGH THE BASE OF THE MEAN MID
LEVEL TROUGH. EXPECTATIONS ARE FOR LITTLE MORE THAN MARGINAL TO
BRIEFLY MODERATE INSTABILITY THIS AFTERNOON WITH MUCAPE VALUES
AROUND 1000 J/KG MAINLY ALONG/EAST OF I-95 THIS AFTERNOON... LIMITED
BY PERSISTENT MOSTLY CLOUDY SKIES THERE... AND DEEP LAYER SHEAR IS
PROJECTED TO BE MARGINAL AS WELL AT 20-25 KTS. WILL RETAIN THE LOW
CHANCE POPS IN THE SE CWA TODAY. THESE CHANCES SHOULD DECREASE
TONIGHT BUT NOT DISAPPEAR ENTIRELY GIVEN THE MOIST COLUMN AND
POTENTIAL FOR ELEVATED INSTABILITY OVERNIGHT. THICKNESSES AND
GUIDANCE TRENDS SUPPORT HIGHS OF 87-94... LOWEST IN THE FAR SE
(CLINTON/MT OLIVE) AND WARMEST IN THE SW. LOWS TONIGHT STILL LOOK
FITTING... 68-74... WITH NUMEROUS INDICATIONS OF STRATUS
REDEVELOPMENT OVERNIGHT. -GIH

&&

.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. CENTRAL NC
WILL REMAIN JUST SOUTH OF THE MAIN BELT OF WESTERLIES...SO DEEP
LAYER BULK SHEAR VALUES AT THIS LATITUDE ARE FORECAST TO BE ONLY
MODEST...BETWEEN ABOUT 15-20 KTS - SUPPORTIVE OF MULTI-CELL STORM
ORGANIZATION.

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 /12Z MONDAY THROUGH THURSDAY/...
AS OF 745 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 SCATTERED TO
BROKEN IFR-MVFR RANGE CLOUDS ACROSS CENTRAL NC THIS MORNING...WITH
THE RELATIVE HIGHEST PROBABILITY OF OCCURRENCE AND LONGEST DURATION
AT FAY. 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...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...26
LONG TERM...ELLIS
AVIATION...26



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