Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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387
FXUS62 KRAH 040800
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
400 AM EDT WED MAY 4 2016

.SYNOPSIS...
LOW PRESSURE AND AN ASSOCIATED TRAILING COLD FRONT WILL MOVE SLOWLY
ACROSS EASTERN NC TODAY AND OFFSHORE THE MIDDLE ATLANTIC COAST THIS
EVENING. MEANWHILE...A POTENT UPPER LEVEL LOW WILL AMPLIFY SOUTHEAST
ACROSS THE CENTRAL APPALACHIANS AND CAROLINAS THROUGH THURSDAY...AND
RESULT IN THE DEVELOPMENT OF RENEWED LOW PRESSURE...AND ASSOCIATED
COOL AND UNSETTLED CONDITIONS...THAT WILL MEANDER OVER THE MIDDLE
ATLANTIC REGION THROUGH THE END OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 400 AM WEDNESDAY...

A COLD FRONT STRETCHED AT 0730Z FROM A 1004 MB SURFACE LOW NEAR KECG
WEST SOUTHWESTWARD TO NEAR KRDU...THEN SOUTH SOUTHWESTWARD TO NEAR
KCAE. THE FRONT...AND FOLLOWING LIGHT NORTH TO NORTHWESTERLY WIND
AND DRIER AIR IN THE LOW LEVELS...WILL CONTINUE TO SETTLE
SOUTHEASTWARD ACROSS EAST-CENTRAL NC DURING THE NEXT SEVERAL HOURS.
PRIOR TO THE PASSAGE OF THE FRONT...HOWEVER...PARTIAL CLEARING AND
RESIDUAL LOW LEVEL MOISTURE THAT HAS BEEN AUGMENTED BY HEAVY
PRECIPITATION IN MANY AREAS...WILL LEAD TO THE SHORT-LIVED
OCCURRENCE OF AREAS OF FOG AND LOW CLOUDS IN THE RESIDUAL WARM
SECTOR. IN ADDITION...A MORE PROLONGED PERIOD OF LOW CLOUDS WILL
DEVELOP SOUTH OUT OF SOUTHEASTERN VA /IMMEDIATELY BEHIND AND IN
PROXIMITY TO THE AFOREMENTIONED SURFACE LOW/ AND CONSEQUENTLY AFFECT
THE NE PIEDMONT AND NRN TO CENTRAL COASTAL PLAIN THROUGH MID TO
LATE MORNING.

OTHERWISE...A LEAD SHORTWAVE TROUGH NOW OVER THE LOWER OH AND TN
VALLEYS WILL LIFT NORTHEASTWARD INTO THE NRN MIDDLE ATLANTIC
STATES BY THIS AFTERNOON...WITH GLANCING FORCING FOR ASCENT LIKELY TO
CONTRIBUTE TO SCATTERED TO OCCASIONALLY BROKEN HIGH-BASED
STRATOCUMULUS BETWEEN 4000-8000 FT OVER CENTRAL NC TODAY...SOME OF
WHICH MAY DEEPEN SUFFICIENTLY --ON THE EASTERN FRINGE OF AN
ASSOCIATED LEAD COLD POOL ALOFT-- TO PRODUCE A FEW SPRINKLES OR
SHOWERS THROUGH EARLY TO MID AFTERNOON...PARTICULARLY ALONG AND EAST
OF I-95. SLIGHTLY COOLER (THAN PREVIOUS DAYS) BEHIND THE FRONT...
WITH HIGH TEMPERATURES MOSTLY IN THE LOWER TO MIDDLE 70S.

A MUCH STRONGER UPPER LEVEL LOW NOW OVER THE UPPER GREAT LAKES WILL
AMPLIFY SOUTH SOUTHEASTWARD INTO THE CENTRAL APPALACHIANS BY 12Z
THU. ASSOCIATED STRONG QG-FORCING FOR ASCENT AND BAND OF MID LEVEL
MOISTURE WILL PIVOT EAST OF THE APPALACHIANS AND INTO CENTRAL NC
LATE TONIGHT...WITH A RENEWED GOOD CHANCE OF SHOWERS OVER THE
PIEDMONT...RANGING TO SLIGHT CHANCE ELSEWHERE. LOWS GENERALLY 50 TO
55 DEGREES.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...

THE POTENT UPPER LEVEL CLOSED LOW WILL SWEEP OVER THE CAROLINAS THU
AND THU NIGHT...WITH THE TROUGH AXIS SLOWLY SHIFTING EASTWARD AND
OFFSHORE BY LATE SATURDAY AS THE LOW ROTATES AROUND TO THE NORTH-
NORTHEAST. AS THE UPPER LEVEL LOW PASSES NEAR OR OVER CENTRAL
NC...THE TROPOPAUSE HEIGHT WILL LOWER SIGNIFICANTLY... CORRESPONDING
TO VERY STRONG PVA OVER THE AREA LATE THU. EXPECT AT LEAST A SLIGHT
CHANCE FOR SHOWERS OVER THE AREA THU THROUGH FRI NIGHT. THE
ASSOCIATED SURFACE LOW WILL LINGER OVER THE MID-ATLANTIC COAST
DURING THAT TIME...WITH GENERALLY WESTERLY OR NORTHWESTERLY FLOW AND
CAA OVER/INTO THE REGION. WINDS WILL BE STRONGEST THU.
HIGHS WILL GENERALLY TOP OUT IN THE MID TO UPPER 60S THU AND FRI.
OVERNIGHT LOWS WILL GENERALLY BE IN THE UPPER 40S TO LOW 50S.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM WEDNESDAY...

AN UPPER LEVEL LOW OVER CANADA WILL STRENGTHEN OVER THE
WEEKEND...WITH THE TROUGH PUSHING SOUTHWARD TOWARD NC. THE
ASSOCIATED BACKDOOR COLD FRONT AT THE SURFACE WILL SLIDE SOUTH...BUT
FOR NOW APPEARS AS THOUGH IT WILL STAY NORTH OF THE VA BORDER. IT
APPEARS SAT AND SUNDAY SHOULD LARGELY REMAIN DRY...HOWEVER A STRAY
SHOWER CANNOT BE COMPLETELY RULED OUT. AS THE SURFACE FLOW SHIFTS TO
MORE WEST AND SOUTHWESTERLY...TEMPS SHOULD REBOUND BACK INTO THE MID
70S SAT TO LOW 80S SUN. THE MEDIUM RANGE MODELS START TO DIFFER
QUITE A BIT FROM SUNDAY ONWARD...RESULTING IN A LOW CONFIDENCE
FORECAST FOR EARLY NEXT WEEK. WILL KEEP THE FORECAST DRY FOR NOW...
WITH HIGHS GENERALLY IN THE LOW TO MID 80S AND LOWS IN THE LOW TO
MID 60S.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 230 AM WEDNESDAY...

A COLD FRONT STRETCHED AT 06Z FROM A 1006 MB SURFACE LOW NEAR KIXA
SOUTH SOUTHWESTWARD ALONG A KHNZ-KBUY-KAFP LINE. THE FRONT...AND
FOLLOWING LIGHT NORTH TO NORTHWESTERLY WIND AND DRIER AIR IN THE LOW
LEVELS...WILL CONTINUE TO SETTLE SOUTHEASTWARD ACROSS CENTRAL NC
DURING THE NEXT SEVERAL HOURS. PRIOR TO THE PASSAGE OF THE
FRONT...HOWEVER...PARTIAL CLEARING AND RESIDUAL LOW LEVEL MOISTURE
THAT HAS BEEN AUGMENTED BY HEAVY RAIN IN MANY AREAS...WILL LEAD TO
THE SHORT-LIVED OCCURRENCE OF AREAS OF FOG AND LOW CLOUDS AROUND
KRDU/KFAY/KRWI. IN ADDITION...A MORE PROLONGED PERIOD OF SUB-VFR
CONDITIONS --MOST LIKELY IN THE FORM OF LIFR-IFR CEILINGS-- WILL
DEVELOP SOUTH OUT OF SOUTHEASTERN VA /IMMEDIATELY BEHIND AND IN
PROXIMITY TO THE AFOREMENTIONED SURFACE LOW/ AND CONSEQUENTLY AFFECT
KRWI THROUGH AROUND 12-13Z. ASSOCIATED CEILINGS WILL LIFT THROUGH
MVFR RANGE AT KRWI AND SCATTER TO VFR BETWEEN 14-17Z.

OTHERWISE...THE APPROACH OF A LEAD SHORTWAVE TROUGH/DISTURBANCE
ALOFT NOW OVER THE LOWER OH AND TN VALLEYS WILL RESULT IN SCATTERED
TO BROKEN HIGH-BASED STRATOCUMULUS BETWEEN 4000-8000 FT...AS WELL AS
THE DEVELOPMENT...AND AT LEAST VICINITY OCCURRENCE...OF SHOWERS THIS
MORNING THROUGH THE END OF THE TAF PERIOD. A FEW LIGHTNING STRIKES
WILL BE POSSIBLE NEAR AND ESPECIALLY JUST EAST OF KRWI EARLY THIS
AFTERNOON...AS DIURNAL HEATING WEAKLY DESTABILIZES THE ATMOSPHERE.

A MUCH STRONGER UPPER LEVEL LOW...AND ASSOCIATED HIGHER PROBABILITY
OF SUB-VFR CEILINGS AND SHOWERS...WILL AMPLIFY INTO NC LATE TONIGHT
(JUST BEYOND THE 06Z TAF PERIOD) THROUGH THU. MULTIPLE SLOW-MOVING
SURFACE WAVES OF LOW PRESSURE ARE FORECAST TO SUBSEQUENTLY DEVELOP
IN THE VICINITY OF THE MIDDLE ATLANTIC COAST MID TO LATE WEEK...WITH
ASSOCIATED PERIODS OF SUB-VFR CEILINGS AND SHOWERS/STORMS THAT WILL
GROW IN COVERAGE AND INTENSITY WITH HEATING EACH AFTERNOON -
ESPECIALLY AT EASTERN TAF SITES.

&&

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

&&

$$
SYNOPSIS...26
NEAR TERM...26
SHORT TERM...10
LONG TERM...10
AVIATION...26



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