Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 020002
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
802 PM EDT FRI MAY 1 2015

.SYNOPSIS...AN UPPER LEVEL LOW AND ASSOCIATED SURFACE LOW WILL MOVE
EAST OF THE AREA TONIGHT...AS HIGH PRESSURE AND MORE SEASONABLE
CONDITIONS SPREAD IN FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 320 PM FRIDAY...

WATER VAPOR AND LATEST RAP DATA SUGGEST THE UPPER LOW IS NOW OVER
THE PAMLICO SOUND AND CONTINUING TO DRIFT EAST...WHILE THE STRONGEST
ASSOCIATED VORTICITY IS NOW OVER SOUTHEASTERN NC.  MOIST
NORTHEASTERLY FLOW...30-35KT AT 850MB...AND ISENTROPIC LIFT OVER THE
NORTHERN COASTAL PLAIN HAS GIVEN WAY TO SOME ISENTROPIC DOWNGLIDE
THIS AFTERNOON PER RAP ANALYSIS. THE STEEPER LAPSE RATES THAT WERE
OVER CENTRAL NC THIS MORNING HAVE ALSO SHIFTED SOUTH/EAST...AND WITH
THE LOSS OF BETTER FORCING/LAPSE RATES...SHOWERS HAVE BECOME MORE
SCATTERED ACROSS THE NORTHERN PIEDMONT/COASTAL PLAIN OVER THE PAST
COUPLE HOURS.  THERE ARE SOME ADDITIONAL SMALL DISTURBANCES IN THE
CYCLONIC FLOW ALOFT THAT SHOULD AID SHOWER ACTIVITY FOR A FEW MORE
HOURS...MOST NOTABLY WITH AN AREA OF SHOWERS MOVING SOUTH THROUGH
SOUTHWESTERN VA.  THE LATEST HRRR SHOWS THIS CONVECTION REACHING THE
TRIAD AROUND 21Z BUT DWINDLING BEFORE MOVING MUCH FURTHER SOUTHEAST
AS HEATING...WHAT LITTLE WE HAVE HAD...IS LOST.  WILL TREND POPS
DOWN FROM WEST TO EAST FOR MOST OF THE AREA...KEEPING A CHANCE POP
ACROSS THE WEST THROUGH 00Z.

TONIGHT...SKIES WILL BEGIN TO CLEAR WITHIN THE SUBSIDENCE BEHIND THE
UPPER LOW...THOUGH GUIDANCE IS IN PRETTY GOOD AGREEMENT ON SOME
LINGERING MOISTURE NEAR 5K FT...WHICH SHOULD ALSO DRIFT SOUTHEAST
WITH TIME AS THE LOW LEVEL FLOW CONTINUES TO BACK AROUND TO MORE
NORTHERLY.  A LIGHT WIND WILL CONTINUE OVER THE COASTAL PLAIN...BUT
BUT TO THE WEST SOME PATCHY FOG SEEMS POSSIBLE GIVEN LITTLE CHANGE
IN AIRMASS AND LIGHT WINDS/DRYING ALOFT. SREF PROBABILITIES FOR FOG
ARE NOT VERY HIGH...SO DENSE FOG IS NOT EXPECTED.  LOWS IN THE UPPER
40S.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 320 PM FRIDAY...

ONE LAST RIBBON OF VORTICITY IS EXPECTED TO DROP SOUTH ACROSS THE
COASTAL PLAIN AROUND MIDDAY...AND ALL MODELS SHOW A SIGNAL FOR AT
LEAST ISOLATED SHOWERS WITH SOME SHALLOW INSTABILITY BEFORE THE
ATMOSPHERE DRIES OUT MORE SUBSTANTIALLY AND STRONGER SUBSIDENCE SETS
IN.  WILL KEEP THE SLIGHT CHANCE POP FROM ROUGHLY ROXBORO TO CLINTON
THROUGH MID AFTERNOON.  HIGHS 72-76 NORTHEAST TO SOUTHWEST.

HIGHS PRESSURE WILL FINALLY BUILD OVERHEAD SATURDAY NIGHT AND SKIES
WILL FULLY CLEAR.  DESPITE THE GOOD RADIATIONAL COOLING
CONDITIONS...THE AIRMASS ACTUALLY MODIFIES SLIGHTLY AND LOWS WILL BE
COMPARABLE TO TONIGHT...IF NOT WARMER IN SOME SPOTS WITH UPPER 40S
AND LOWER 50S.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
AS OF 240 PM FRIDAY...

HIGH PRESSURE OVERHEAD ON SUNDAY WILL SLOWLY MIGRATE OFFSHORE BUT
CONTINUE TO RIDGE WESTWARD INTO NC THROUGH TUESDAY. A WEAK TROUGH
WILL GET SANDWICHED BETWEEN THE EXITING HIGH AND A HIGH OVER THE
GREAT LAKES MID-WEEK. ALTHOUGH SOME OF THE MODELS INDICATE A SLIGHT
CHANCE FOR SOME SHOWERS IN THE FAR NORTHWEST DURING THE AFTERNOON
PERIODS MON-WED...MOST OF THE SHOWER ACTIVITY SHOULD STAY WELL TO
THE NORTH AND NORTHWEST. CENTRAL NC WILL REMAIN UNDER HIGH PRESSURE
BUT GENERALLY WEAK SURFACE FLOW FOR THE REMAINDER OF THE WEEK.
WEDNESDAY THROUGH FRIDAY GETS INTERESTING TO OUR SOUTHEAST AS BOTH
THE GFS AND ECMWF GENERATE A TROPICAL LOW PRESSURE SYSTEM OVER THE
CARIBBEAN...MOVING SLOWLY NORTH AND STALLING OFF THE CAROLINA COAST.
WHILE THERE IS STILL A GOOD DEAL OF UNCERTAINTY WITH THIS SYSTEM
GIVEN THAT IT IS FAR OUT IN THE MODEL FORECAST PERIOD...THE FACT
THAT BOTH MODELS SHOW SIMILAR FEATURES INCREASES THE CHANCE THAT
SOMETHING OF INTEREST WILL DEVELOP OFF THE SOUTHEAST ATLANTIC COAST
TOWARD THE END OF THE WEEK. REGARDLESS...ITS EVOLUTION WILL BE
SOMETHING TO WATCH. AS FOR TEMPERATURES...STILL EXPECT OUR FIRST
EXTENDED PERIOD OF 80 DEGREE DAYS...WITH HIGHS INCREASING ABOUT A
DEGREE OR SO A DAY FROM THE MID TO UPPER 70S ON SUNDAY INTO THE LOW
TO MID 80S BY FRIDAY. LOWS WILL SEE A SIMILAR TREND...INCREASING
FROM THE MID 50S SUNDAY NIGHT INTO THE UPPER 50S TO LOW 60S BY
FRIDAY NIGHT. SKIES WILL GENERALLY BE CLEAR TO PARTLY CLOUDY THROUGH
MOST OF THE PERIOD...WITH FAIRLY LIGHT WINDS...EXCEPT IN THE
SOUTHEAST AS THAT LOW HANGS OFF THE CAROLINA COAST.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 800 PM FRIDAY...

SHOWER ACTIVITY CONTINUES TO DIMINISH ACROSS THE AREA. VFR
CONDITIONS ARE EXPECTED TO PREVAIL DURING THE NEXT 24 HOURS... AS
THE UPPER LEVEL LOW PULLS AWAY FROM THE COAST AND SURFACE HIGH
PRESSURE BUILDS IN TO THE AREA. THERE IS A CHANCE OF PATCHY FOG
OVERNIGHT AS CLOUD COVER CONTINUES TO DIMINISH... BUT CONFIDENCE IS
TOO LOW FOR ANY SITE OTHER THAN KRWI TO INCLUDE MENTION AT THIS TIME.

OUTLOOK... VFR CONDITIONS ARE LIKELY TO CONTINUE THROUGH THE WEEKEND
IN TO EARLY NEXT WEEK AS HIGH PRESSURE MOVES ACROSS THE AREA.

&&

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

&&

$$

SYNOPSIS...22
NEAR TERM...22
SHORT TERM...22
LONG TERM...KC
AVIATION...30


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