Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 031045
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
644 AM EDT THU SEP 3 2015

.SYNOPSIS...A DISTURBANCE ALOFT WILL CROSS EASTERN PORTIONS OF
CENTRAL NC THIS MORNING. A LEE TROUGH WILL OTHERWISE LINGER OVER
CENTRAL NC UNTIL A BACK DOOR COLD FRONT MOVES SOUTHWEST ACROSS THE
AREA LATE FRI AND FRI NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM THURSDAY...

REST OF THIS MORNING AND TODAY: LINGERING CONVECTION... ASSOCIATED
WITH A DISTURBANCE ALOFT MOVING ACROSS THE AREA THIS MORNING...
SHOULD GENERALLY SHIFT TO THE EAST OF CENTRAL NC WITHIN A COUPLE OF
HOURS... GENERALLY ENDING ANY LINGERING THREAT THIS MORNING OF ANY
SHOWERS AND STORMS. HOWEVER... SOME PATCHY FOG AND STRATUS HAS AND
WILL LIKELY DEVELOP ACROSS PORTIONS OF THE AREA THIS MORNING...
MAINLY ACROSS LOCATIONS THAT SAW A DECENT AMOUNT OF PRECIP FROM THE
AFOREMENTIONED DISTURBANCE... AS SKIES ARE CLEARING OFF BEHIND THE
DISTURBANCE.

ANY FOG AND LOW STRATUS THAT DEVELOPS THIS MORNING SHOULD LIFT AFTER
SUNRISE. EXPECT GENERALLY DRY CONDITIONS FOR TODAY WITH... ONLY A
LOW CHANCE OF SEEING ANY SHOWERS AND STORMS THIS AFTERNOON... MAINLY
ALONG AND EAST OF A WEAK SURFACE TROUGH... EXPECTED TO BE LOCATED
ACROSS THE EASTERN/SOUTHEASTERN THIRD OF CENTRAL NC. IN ADDITION...
A TRAILING LINGERING PIECE OF THE DISTURBANCE ALOFT... WHICH IS
PASSING THROUGH THE AREA CURRENTLY... MAY ALLOW FOR THE BEST CHANCE
OF SEEING SOME SHOWERS AND STORMS ACROSS OUR FAR SOUTHEASTERN
COUNTIES... THIS IS WHERE WE SHOULD HAVE THE BEST SURFACE
INSTABILITY AS WELL. HOWEVER... WITH WEAK DEEP LAYER SHEAR AND ONLY
MODEST INSTABILITY AT BEST... WE DO NOT EXPECT ANY SEVERE STORMS
TODAY. HIGH TEMPS WILL AGAIN BE IN THE UPPER 80S TO LOWER 90S...
WITH A FEW LOCATIONS MAKING IT INTO THE MID 90S... THANKS TO A
FAIRLY DEEP MIX LAYER AND AFTERNOON LOW LEVEL THICKNESS VALUES NEAR
1430 METERS.

TONIGHT: A FAIRLY WEAK NORTHWEST MID LEVEL FLOW ALOFT MAY ALLOW FOR
A WEAK DISTURBANCE OR TWO TO CROSS THE AREA THIS EVENING OR
OVERNIGHT TONIGHT. HOWEVER... WITH THE LOSS OF DAYTIME HEATING WE
WILL ONLY KEEP A SLIGHT CHANCE OF SHOWERS ACROSS THE NORTHERN
PORTION OF THE AREA FOR TONIGHT (WITH MOST LOCATIONS LIKELY
REMAINING DRY). OVERNIGHT LOW ARE EXPECTED TO BE IN THE UPPER 60S TO
LOWER 70S.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 320 AM THURSDAY...

A S/W DISTURBANCE AND ASSOCIATED SURFACE LOW WILL TRACK
EASTWARD AND OFF OF SE CANADIAN COAST ON LATE TODAY AND TONIGHT. THE
TRAILING COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL PUSH
SOUTH/SOUTHWESTWARD IN BACKDOOR FASHION ACROSS CENTRAL NC LATE
FRIDAY INTO FRIDAY NIGHT. THIS COUPLED WITH ANOTHER WEAK DISTURBANCE
PASSING THROUGH THE REGION IN THE WEAK NORTHWESTERLY FLOW ALOFT WILL
ALLOW FOR SCATTERED SHOWERS AND STORMS TO DEVELOP LATE INTO THE DAY
AND INTO THE EVENING... POSSIBLY LINGERING INTO THE EARLY MORNING
HOURS OF FRIDAY ACROSS THE WESTERN/SOUTHWESTERN PORTION OF THE AREA.
DESPITE BETTER INSTABILITY... LOW LEVEL CONVERGENCE WILL REMAIN WEAK
ALONG WITH THE DEEP LAYER SHEAR. THUS... WE DO NOT EXPECT TO SEE ANY
SEVERE WEATHER. HOWEVER... WITH SUCH A WEAK FLOW AND PW`S OF AROUND
1.75"... WE COULD SEE SOME LOCALIZED FLOODING... MAINLY IN URBAN
AREAS AND POOR DRAINAGE AREAS (THOUGH THIS SHOULDN`T BE WIDESPREAD).
HIGHS ON FRIDAY ARE EXPECTED TO BE IN THE LOWER 90S... WITH PERHAPS
A FEW LOCATIONS TOUCHING THE MID 90S AGAIN. LOWS SATURDAY MORNING
ARE EXPECTED TO BE IN THE UPPER 60S TO LOWER 70S.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 310 AM THURSDAY...

LOW LEVEL NELY FLOW WILL DEVELOP OVER THE REGION SATURDAY IN THE
WAKE OF THE DEPARTING SURFACE BOUNDARY AS A SFC HIGH OVER SOUTHERN
NEW ENGLAND NOSES SOUTHWARD. THIS LOW LEVEL FLOW APPEARS TO HAVE A
DECENT FETCH OFF THE ATLANTIC. THUS...THIS WILL SET UP A BATTLE
BETWEEN THE DRIER AIR MASS UNDERNEATH THE SURFACE RIDGE AND THE
MOIST AIR INTRUDING WESTWARD OFF THE ATLANTIC. THE
ORIENTATION/POSITION OF THE SURFACE RIDGE SUGGEST THE DRIER AIR WILL
LIKELY BE IMMEDIATELY TO OUR WEST (OVER THE HIGHER TERRAIN OF
WESTERN NC). IN ADDITION...LOW LEVEL FLOW WILL HAVE AN UPSLOPE
COMPONENT. THUS...EXPECT TO SEE A GOOD DEAL OF CLOUDINESS BOTH
SATURDAY AND SUNDAY ACROSS THE REGION.

STILL MUCH UNCERTAINTY AS TO THE EXTENT OF SHOWER COVERAGE TO OCCUR.
THE GFS HAS BEEN TRENDING TOWARD THE WETTER ECMWF SOLUTION THE PAST
FEW RUNS. BOTH MODELS SUGGEST EITHER A LINGERING  SHEAR AXIS
OVERHEAD OR A SERIES OF WEAK PERTURBATIONS WORKING THEIR WAY WEST
OFF THE ATLANTIC. PRESENCE OF A COASTAL TROUGH SHOULD FOCUS BEST LOW
LEVEL CONVERGENCE OVER THE COASTAL PLAIN...WHILE AFTERNOON HEATING
AND LOW LEVEL UPSLOPE COMPONENT SHOULD AID ADDITIONAL DEVELOPMENT IN
THE AFTERNOON-EARLY EVENING OVER CENTRAL NC. STILL...FORCING APPEARS
WEAK SO FAVOR POPS IN THE SLIGHT CHANCE-CHANCE RANGE SATURDAY AND
SUNDAY. ONCE A DISCERNIBLE FEATURE NOTED...THEN POPS MAY HAVE TO BE
TWEAKED HIGHER OR CONCENTRATED OVER A CERTAIN SECTION OF THE
FORECAST REGION.

STILL FEEL FAIRLY CERTAIN THAT WE SHOULD SEE NEAR OR BELOW NORMAL
TEMPS THIS WEEKEND. IF CLOUDS AND/OR PRECIP MORE EXTENSIVE THAN
CURRENT THINKING...THEN MUCH OF THE PIEDMONT MAY NOT REACH ABOVE 80
BOTH DAYS. FOR NOW WILL TARGET MAX TEMPS IN THE PIEDMONT NEAR 80-
LOWER 80S WITH MID 80S COMMON OVER THE EAST AND SE.

THE LOW LEVEL E-NE FLOW WILL BEGIN TO ABATE MONDAY AND MORE SO
TUESDAY INTO WEDNESDAY. THIS SIGNALS A RETURN TO SLIGHTLY DRIER AND
WARMER CONDITIONS THROUGH THIS PERIOD WITH THE BULK OF THE PRECIP
DIURNALLY DRIVEN. LOW LEVEL THICKNESSES BY MID WEEK AVERAGE 20M
ABOVE NORMAL. THIS SUGGEST AFTERNOON TEMPS REBOUNDING BACK INTO THE
85-90 DEGREE RANGE BY TUESDAY AND WEDNESDAY.


&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 640 AM THURSDAY...

AN AREA OF IFR/LIFR FOG AND STRATUS HAS DEVELOPED THIS MORNING
ACROSS NORTHEASTERN PORTIONS OF CENTRAL NC... AFFECTING KRWI AND
KRDU. EXPECT THESE RESTRICTION TO LIFT WITHIN AN HOUR OR TWO OF
SUNRISE... WITH VFR CONDITIONS GENERALLY EXPECTED FOR THE REMAINDER
OF THE TAF PERIOD. THERE IS A SLIGHT CHANCE OF SEEING SOME SHOWERS
AND STORMS ACROSS CENTRAL NC TODAY THOUGH. HOWEVER... PROBABILITIES
REMAIN TOO LOW TO INCLUDE ANY MENTION IN THE TAFS AT THIS TIME.
PATCHY SUB-VFR VISBYS AND CIGS WILL BE POSSIBLE AGAIN TOMORROW
MORNING... ESPECIALLY FOR LOCATIONS THAT HAPPEN TO RECEIVE A SHOWER
AND/OR STORM TODAY/THIS EVENING.

LOOKING AHEAD: CONVECTION WILL BE POSSIBLE IN ASSOC/W A COLD FRONTAL
PASSAGE ON FRIDAY. HIGH PRESSURE WILL EXTEND INTO THE REGION FROM
THE N/NE IN THE WAKE OF THE FRONT...RESULTING IN A SYNOPTIC PATTERN
REMINISCENT OF COLD AIR DAMMING. AS A RESULT...SUB-VFR CEILINGS WILL
BE POSSIBLE AT ALL TERMINALS OVER THE WEEKEND. -VINCENT

&&

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

&&

$$

SYNOPSIS...77/26
NEAR TERM...BSD
SHORT TERM...BSD
LONG TERM...WSS
AVIATION...BSD/VINCENT


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