Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 281526
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1126 AM EDT SUN JUL 28 2014

.SYNOPSIS...A STRONG COLD FRONT WILL CROSS THE AREA THIS
AFTERNOON... BRINGING NOTICEABLY COOLER AND LESS HUMID AIR INTO THE
AREA. HIGH PRESSURE BUILDS OVER MUCH OF THE REGION FOR TUESDAY INTO
WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1120 AM MONDAY...

HARD TO IMAGINE THAT SUCH STRONG DYNAMICS AND THE PASSAGE OF A
SURFACE FRONT IN LATE JULY WOULD RESULT IN SO LITTLE RAINFALL FOR
CENTRAL NC...AND THAT WHAT LITTLE RAIN THAT DID OCCUR RESULTED FROM
AN MCV WELL DOWNSTREAM OF THE STRONGEST FORCING FOR ASCENT WITH THE
UPPER TROUGH AND ACCOMPANYING LOW LEVEL FRONTAL ZONE. OVERWHELMING
NOCTURNAL CINH FOLLOWED THIS MORNING BY DOWNSLOPE FLOW HAS SIMPLY
PROVEN TOO GREAT TO OVERCOME.

MOISTURE CHANNEL AND BLENDED TPW IMAGERY INDICATE DEEP DRYNESS...AND
CAPPING/STABILITY PER PROXIMITY RAOBS AWAY FROM COASTAL AREAS...HAS
ENVELOPED ALL BUT SE NC THIS MORNING. PRECIPITATION CHANCES FOR THE
REMAINDER OF TODAY WILL CONSEQUENTLY NOW BE CONFINED TO THE SOUTHERN
SANDHILLS AND SOUTHERN AND CENTRAL COASTAL PLAIN...INVOF AND AHEAD
OF A SFC TROUGH/FRONT THAT WILL BECOME BETTER DEFINED FROM NEAR THE
NC OUTER BANKS TO THE SANDHILLS TO THE SC UPSTATE...AS DRY AIR IN
THE 850-925 MB LAYER IS IMPARTED ON THE SFC WITH HEATING/MIXING.
THESE AREAS WILL BE ON THE NW EDGE OF MODERATE INSTABILITY FORECAST
TO DEVELOP OVER COASTAL AREAS...FUELED BY KMHX 12Z-OBSERVED MID
LEVEL LAPSE RATES IN EXCESS OF 7 C/KM. IN ADDITION...A BELT OF
STRONG (40-50 KT) MID LEVEL FLOW OBSERVED FROM THE NORTHERN PLAINS-
TN VALLEY-NC COAST WILL PROVIDE AMPLE DEEP LAYER SHEAR...
CHARACTERIZED BY LONG AND STRAIGHT FORECAST HODOGRAPHS AT KFAY AND
KILM THROUGH 00Z - SUPPORTIVE OF A CONDITIONAL SVR RISK OF DAMAGING
WIND GUSTS AND LARGE HAIL (LIKELY FROM SPLITTING SUPERCELLS PROVIDED
STORMS CAN BOTH DEVELOP AND NOT SUCCUMB TO ENTRAINMENT OF THE
AFOREMENTIONED DRY AIR ALOFT). HOWEVER...THIS PROBABILITY OF STORMS
FORMING AND THRIVING IN THE RAH CWFA IS RELATIVELY LOW - ONLY AROUND
20 PERCENT.

OTHERWISE...A RELATIVELY TIGHT MSL PRESSURE GRADIENT ABOUT THE SFC
FRONT WILL GENERATE A BREEZY GENERALLY WESTERLY SFC WIND (WNW OVER
THE PIEDMONT TO WSW OVER THE SANDHILLS AND COASTAL PLAIN)...WITH
GUSTS UP TO 20-25 MPH. LOW LEVEL THICKNESS VALUES AROUND 1425 METERS
SUPPORT HIGH TEMPERATURES IN THE MID-UPPER 80S NW TO LOWER-MID 90S
SE. LOWS GENERALLY WITHIN A FEW DEGREES EITHER SIDE OF 65.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
AS OF 240 AM MONDAY...

UPPER LEVEL TROUGHING WILL STAY IN PLACE OVER THE EAST COAST
THROUGHOUT THE SHORT TERM PERIOD...WHILE AT THE SURFACE
COOL...CANADIAN HIGH PRESSURE WILL GRADUALLY SETTLE EAST OVER THE
EAST COAST...KEEPING THE FRONT OFFSHORE. ALL OF THIS WILL LEAD TO
BELOW NORMAL TEMPS...WITH HIGHS GENERALLY IN THE LOW/MID 80S AND
OVERNIGHT LOWS IN THE LOW/MID 60S...POSSIBLY EVEN SOME UPPER 50S IN
THE NORMAL COOLER SPOTS. IN ADDITION...MOSTLY DRY CONDITIONS ARE
EXPECTED THROUGH AT LEAST THURSDAY AS NORTHWESTERLY FLOW ALOFT
MAINTAINS A DRY COLUMN...WITH PWAT VALUES PROGGED TO HOVER JUST
ABOVE 1 INCH.

&&

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

BY LATE IN THE WEEK AND ESPECIALLY INTO THE WEEKEND...THE HIGHLY
AMPLIFIED RIDGE OVER THE ATLANTIC WILL SHIFT WESTWARD...NUDGING THE
UPPER LEVEL TROUGH BACK TOWARDS THE MS RIVER VALLEY. AS A
RESULT...THE LINGERING FRONT/INVERTED TROUGH WILL WILL ALSO MOVE
CLOSER TO THE COAST...AND LIKELY INLAND BY THE LATTER HALF OF THE
WEEKEND. IN ADDITION...MOISTURE WILL GRADUALLY INCREASE (PWATS
RISING BACK OVER 1.5 INCHES BY SATURDAY...THEN APPROACHING  2 INCHES
BY SUNDAY) AS FLOW ALOFT BECOMES MORE SOUTHWESTERLY. AS A RESULT OF
ALL OF THIS...WILL SHOW PRECIP CHANCES GRADUALLY INCREASING INTO THE
30-40 PERCENT RANGE BY SUNDAY. HIGH TEMPS WILL STILL BE IN THE
LOW/MID 80S...WITH OVERNIGHT LOWS IN THE LOW/MID 60S.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS OF 730 AM MONDAY...

DRIER AIR WILL ALOFT AND AT THE SURFACE WILL CONTINUE TO SPREAD WEST
TO EAST INTO CENTRAL NORTH CAROLINA THROUGH THE DAY ON MONDAY AS A
STRONG COLD FRONT CROSSES THE AREA. THIS SHOULD SHIFT THE FOCUS FOR
CONVECTIVE INITIATION ACROSS SOUTHEASTERN NC. LATEST HI-RES
CONVECTIVE ALLOWING MODELS HAVE ALL RE-DEVELOPMENT WELL EAST OF KFAY
AND KRWI AND THUS DO NOT PLAN ON CARRYING ANY MENTION OF THUNDER
WITH THE 12Z ISSUANCE. AS SUCH...EXPECT VFR CONDITIONS WITH DAYTIME
MIXING RESULTING IN WESTERLY WIND GUSTS TO AROUND 20KTS.

BEYOND THE 24 HOUR TAF PERIOD...VFR CONDITIONS SHOULD PREVAIL FOR
MUCH OF THE REST OF THE WORK WEEK...WITH INCREASING CHANCES FOR
SHOWERS AND THUNDERSTORMS FROM FRIDAY INTO THE WEEKEND.

&&

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

&&

$$

SYNOPSIS...DJF
NEAR TERM...MWS
SHORT TERM...KRR
LONG TERM...KRR
AVIATION...CBL


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