Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 272317 CCA
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
717 PM EDT MON APR 27 2015

.SYNOPSIS...HIGH PRESSURE BUILDING INTO THE REGION TODAY WILL LINGER
THROUGH TUESDAY NIGHT. MEANWHILE...AN AREA OF LOW PRESSURE WILL
DEVELOP ALONG THE GULF COAST...THEN TRACK NORTHEAST ALONG THE
CAROLINA AND MID-ATLANTIC COAST WEDNESDAY INTO THURSDAY.

&&

.NEAR TERM /TONIGHT/...
AS OF 230 PM MONDAY...

A POTENT SHORTWAVE CENTERED INVOF SOUTHWEST PA AT 18Z WILL TRACK ESE
TO THE DELMARVA BY 00Z BEFORE PROGRESSING OFFSHORE BY MIDNIGHT.
ADDITIONAL SHORTWAVE ENERGY ON THE HEELS OF THE FORMER WAVE IS
PROGGED TO TAKE A SOUTHERLY TRACK INTO THE CAROLINAS OVERNIGHT.
ALTHOUGH STRONG DPVA WILL BE PRESENT IN ASSOC/W THE FIRST WAVE THIS
EVENING...THE BULK OF THIS FORCING WILL REMAIN WELL NORTHEAST OF
CENTRAL NC ACROSS TIDEWATER VA AND PORTIONS OF THE DELMARVA. EVEN IF
THIS FEATURE WERE TO AFFECT THE NE COASTAL PLAIN...THE ATMOSPHERE
/THERMODYNAMIC ENVIRONMENT/ IN PLACE ACROSS CENTRAL NC IS
INSUFFICIENTLY MOIST TO SUPPORT PRECIPITATION. BASED ON SIMILAR
REASONING...IN ADDITION TO POOR DIURNAL TIMING AND LOW-LEVEL COLD
ADVECTION...EXPECT NO CHANCE FOR PRECIP OVERNIGHT AS THE SECONDARY
SHORTWAVE TRACKS SOUTHWARD INTO CENTRAL NC. STRONG RADIATIONAL
COOLING POTENTIAL EXISTS TONIGHT GIVEN MOSTLY CLEAR SKIES AND A VERY
DRY AIRMASS IN PLACE...HOWEVER...FULL RADIATIONAL COOLING IS
UNLIKELY TO BE ACHIEVED GIVEN THE PRESENCE OF A PERSISTENT NORTHERLY
BREEZE...ASSOC/W PRESSURE RISES ATTENDANT SFC HIGH PRESSURE BUILDING
INTO THE REGION FROM THE NW. AS A RESULT...EXPECT LOWS RANGING FROM
THE UPPER 30S IN THE TYPICAL RURAL AND LOW-LYING AREAS TO LOW/MID
40S ELSEWHERE. -VINCENT

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 230 PM MONDAY...

TUESDAY AND TUESDAY NIGHT: DRY CONDITIONS WILL PERSIST DURING THE
DAY TUE...WITH HIGHS IN THE UPPER 60S TO NEAR 70F. A DRY SFC RIDGE
EXTENDING INTO THE REGION FROM THE NORTHWEST WILL GRADUALLY WEAKEN
TUE AFT/EVE INTO TUE NIGHT AS A POTENT SOUTHERN STREAM WAVE
PROGRESSES EAST ACROSS THE LOWER MS RIVER VALLEY...WITH AN ATTENDANT
SFC LOW DEEPENING ALONG THE GULF COAST. THE UPPER WAVE AND ATTENDANT
SFC CYCLONE WILL BECOME CLOSE TO MATURE /VERTICALLY STACKED/ OVER
PORTIONS OF THE DEEP SOUTH BY 12Z WED. EXPECT TOP-DOWN MOISTENING
OVERNIGHT...I.E. ADVECTION OF MID/UPPER LEVEL MOISTURE DOWNSTREAM OF
THE MATURE CYCLONE INTO CENTRAL NC BY ~MIDNIGHT... FOLLOWED BY
STRENGTHENING LOW-LEVEL WARM ADVECTION AND AN INCREASING CHANCE FOR
LIGHT RAIN IN THE SANDHILLS AND WEST/SW PIEDMONT BY SUNRISE WED.
GIVEN A RAPID INCREASE IN CLOUD COVER...EXPECT LOWS MARKEDLY WARMER
THAN PREVIOUS NIGHTS...IN THE UPPER 40S TO LOWER/MID 50S...COOLEST
IN THE WEST/SW PIEDMONT WHERE PRECIP WILL DRIVE TEMPS DOWNWARD VIA
EVAP COOLING JUST PRIOR TO SUNRISE. -VINCENT

WEDNESDAY AND WEDNESDAY NIGHT: MODELS ARE IN FAIRLY GOOD AGREEMENT
WITH THE APPROACH OF THE TIMING AND STRENGTH OF THE MID/UPPER LOW AS
IT IS FORECAST TO TRACK OUT OF THE SOUTHERN PLAINS TOWARD THE
MISSISSIPPI VALLEY REGION TOWARD OUR REGION BY MID WEEK. COOL DRY
SURFACE HIGH PRESSURE IS INITIALLY FORECAST TO EXTEND FROM THE GREAT
LAKES SOUTH INTO THE CAROLINAS TUESDAY NIGHT AND WEDNESDAY. THE HIGH
IS FORECAST TO BE FAIRLY WEEK (1020 MB OR SO)... BUT WILL DEPOSIT
PLENTY OF DRY AIR OVER THE REGION BEFORE THE RAIN BEGINS WEDNESDAY
TO LEAD TO EVAPORATIVE COOLING AND AT LEAST A HYBRID COLD AIR
DAMMING RESUME WEDNESDAY AFTERNOON AND NIGHT. AS IT APPEARS WITH THE
RECENT MODELS RUNS... CONSENSUS IS FOR INCREASING CLOUDINESS TUESDAY
NIGHT WITH LOWS IN THE UPPER 40S TO LOWER 50S. THEN RAIN LIKELY
DEVELOPING FROM SOUTHWEST TO NORTHEAST WEDNESDAY. HIGHS WILL DEPEND
ON THE RAIN ARRIVAL. EXPECT GENERALLY 50S WEST TO SOME LOWER 60S
EAST. RAIN NOW APPEARS LIKELY WEDNESDAY AFTERNOON AND NIGHT. LOWS 50-
55 WEDNESDAY NIGHT.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 140 PM MONDAY...

...DAMP AND CHILLY THURSDAY FOLLOWED BY A MODERATION AND DRYING THIS
WEEKEND...

MODELS ARE FINALLY IN GOOD OVERALL AGREEMENT IN BRINGING A STORM
SYSTEM UP ALONG THE SOUTHEAST AND MID-ATLANTIC COAST THURSDAY INTO
FRIDAY. THIS IS A PATTERN THAT MORE RESEMBLES THE COLD SEASON THAN
THE WARM SEASON AND ONE THAT WILL ONLY MODIFY SLOWLY INTO THE
WEEKEND GIVEN THE COOL/RAINY CONDITIONS AND NE FLOW EXPECTED WITH
THE COASTAL STORM.

THE COASTAL LOW PRESSURE IS FORECAST TO START THE DAY NEAR THE SC/NC
COAST AROUND 12Z/THURSDAY... THEN DEEPEN AS IT MOVES NE TO ALONG AND
OFF THE MID-ATLANTIC TO NEW ENGLAND COAST BY 12Z/FRIDAY. THIS STORM
TRACK FAVORS A COOL STABLE NE FLOW ACROSS OUR REGION WITH STRATIFORM
RAIN AND IS NOT FAVORABLE FOR SEVERE STORMS AS THE WARM SECTOR IS
EXPECTED TO BE WELL SOUTH AND EAST (OFFSHORE). MODELS HAVE TRENDED A
BIT WESTWARD WITH THE MID/UPPER LOW POSITION IN THE PAST FEW RUNS...
AND THIS IN TURN ALLOWS A MORE WESTWARD TRACK OF THE COASTAL LOW
ALLOWING FOR WIDESPREAD QPF ON THE ORDER OF 1-2 INCHES.

SENSIBLE WEATHER SHOULD BE FOR THE STEADY AND HEAVIER RAIN TO FALL
INTO A PART OF THURSDAY... THEN GRADUALLY TAPER OFF AS THE COASTAL
LOW PULLS UP THE COAST LEAVING BEHIND A CHILLY NE FLOW... AREAS OF
LIGHT RAIN.... DRIZZLE... AND OVERCAST LOW CLOUDINESS DURING THE
DAY. TEMPERATURES SHOULD ONLY REACH THE UPPER 50S AND 60S (MOST
LIKELY A GOOD 15 DEGREES BELOW THE NORMAL). THEN DEPENDING ON THE
MID/UPPER LOW TRACK GIVEN POTENTIAL INTERACTION WITH THE POLAR
JET... EITHER SLOW CLEARING THURSDAY NIGHT AND BECOMING PARTLY SUNNY
FRIDAY OR... IF THE TRACK IS OVERHEAD THERE WILL BE A CONTINUED
CHANCE OF SHOWERS AND POSSIBLY SOME THUNDERSTORMS WITH COLD AIR
ALOFT AND SURFACE HEATING FRIDAY. REGARDLESS... TEMPERATURES WILL
REMAIN COOL. HIGHS FRIDAY GENERALLY EXPECTED TO REACH 65-70 WITH THE
LOW LEVEL FLOW FROM THE NORTH.

FINALLY... A MODERATING TREND IS EXPECTED OVER THE WEEKEND INTO
EARLY NEXT WEEK AS THE STORM DEPARTS AND HIGH PRESSURE IS FORECAST
TO BUILD OVERNIGHT. LOWS SHOULD MODERATE FROM THE MID 40S TO LOWER
50S SATURDAY INTO THE MID AND UPPER 50S MONDAY. HIGHS SHOULD REACH
CLOSE TO NORMAL LEVELS BY SUNDAY OR MONDAY (UPPER 70S TO LOWER
80S).

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
AS OF 715 PM MONDAY...

24-HOUR TAF PERIOD: HIGH CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL
THROUGH THE TAF PERIOD. SOME SCATTERED CLOUDS AROUND 7 KFT MAY
LINGER FOR THE NEXT FEW HOURS...MAINLY IN THE NORTHEAST...BECOMING
CLEAR ELSEWHERE. WIND GUSTS HAVE DISSIPATED AND EXPECT WINDS TO BE
AROUND 5 KTS...POSSIBLY GOING CALM TO VERY LIGHT OVERNIGHT...AND
BECOMING MORE NORTHERLY BY TUESDAY AFTERNOON. HIGH CLOUDS WILL START
TO BUILD IN TOWARD THE END OF THE TAF PERIOD...BUT WILL LEAVE OUT
FOR NOW.

LOOKING AHEAD: THE PASSAGE OF A COASTAL LOW PRESSURE SYSTEM WILL
RESULT IN A GOOD CHANCE OF SUB-VFR CONDITIONS AND RAIN LATE TUE
NIGHT THROUGH THU MORNING AT ALL TERMINALS...WITH THE LONGEST
DURATION OF SUB-VFR CONDITIONS AT EASTERN (FAY/RWI) TERMINALS WHERE
PRECIP WILL LINGER THE LONGEST. -VINCENT

&&

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

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...VINCENT/BADGETT
LONG TERM...BADGETT
AVIATION...RAH/VINCENT



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