AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
240 PM EDT SUN APR 20 2014

.SYNOPSIS...LOW PRESSURE OFF THE SE COAST WILL CONTINUE MOVING EAST 
AND OUT INTO THE ATLANTIC...LEAVING BEHIND A COOL WEDGE OF HIGH 
PRESSURE ON MONDAY. A COLD FRONT WILL CROSS THE REGION ON 
TUESDAY...WITH HIGH PRESSURE RETURNING FOR MIDWEEK. 

&&

.NEAR TERM /THROUGH MONDAY NIGHT/... 
AS OF 220 PM SUNDAY... 

TODAY: VERTICALLY STACKED LOW WILL DRIFT SLOWLY EASTWARD AND AWAY 
FROM SHORE THROUGH TONIGHT. EXPECT VERY DELIBERATE...IN FACT 
SLOTH-LIKE IMPROVEMENT TO SPREAD EASTWARD THROUGH TONIGHT WITH WESTERN 
PORTIONS UNDER THE INFLUENCE OF THE DRY AIR RIDGE FROM THE 
NORTH...YIELDING DRY CONDITIONS WITH FULL COMPLIMENTS OF SUN TODAY. 
MEANWHILE...EASTERN PORTIONS OF THE FORECAST AREA WILL REMAIN MOSTLY 
CLOUDY FOR A GOOD PART OF THE DAY WITH WANING ONSHORE CONVERGENT 
FLOW SUPPORTIVE OF PATCHY AND MOSTLY TRACE AMOUNTS OF PRECIP. 

THIS WEST TO EAST CLOUD GRADIENT WILL GOVERN HIGHS TODAY...WITH 
STRONGER ISOLATION OUT WEST SUPPORTING SOME OF THE WARMEST READINGS. 
HIGHS RANGING FROM UPPER 60S WEST TO LOWER 60S SOUTHEAST.  WITH THE 
MSLP GRADIENT STAYING TIGHT ESPECIALLY FROM THE TRIANGLE SOUTH AND 
EAST... EXPECT THE STEADY BRISK AND OCCASIONALLY GUSTY WINDS TO 
CONTINUE TODAY... MOST MARKEDLY IN THE ERN CWA.

TONIGHT: THERE REMAINS SOME UNCERTAINTY WITH RESPECT TO THE 
DEVELOPMENT OF LOW STRATUS TONIGHT. WHILE NOT AS MOIST AS LAST 
NIGHTS CYCLE...12Z/20 NAM BUFR SOUNDINGS STILL SUGGEST THAT AS THE 
BOUNDARY LAYER COOLS...LOW STRATUS WILL BE APT TO FORM OWING 
TO THE RELATIVELY DEEP NELY ONSHORE FLOW. THE GFS IS MUCH DRIER IN 
THE LOWER LEVELS...SUGGESTING LITTLE IN THE WAY OF SUB-VFR CEILINGS. 
EXPECT WE WILL SEE AT LEAST SOME RETURN OF CLOUDS INTO THE COASTAL 
PLAIN...AND AS POSSIBLY FAR INLAND AS SAY THE EASTERN/CENTRAL 
PIEDMONT. WILL INDICATE THIS IN THE FORECAST WITH BROKEN MVFR 
CEILINGS AT KRWI AND KFAY. LOWS IN THE LOWER 40 TO MID 40S...COOLEST 
ACROSS THE NW. 

FOR MONDAY/MONDAY NIGHT: STRONG PARENT HIGH OVER THE NORTHEAST WILL 
RETREAT OUT INTO THE ATLANTIC...LEAVING BEHIND THE RESIDUAL DRY AIR 
SURFACE RIDGE WHICH WILL WEAKEN/BREAK DOWN THROUGHOUT THE DAY. 
ALOFT...MID LEVEL SHORTWAVE RIDGE WILL BUILD OVER THE AREA IN 
ADVANCE OF THE PROGRESSIVE POSITIVE-TILT LONG-WAVE TROUGH 
PROGRESSING EASTWARD THROUGH THE CENTRAL US. ALL OF THE 
FORECAST AREA WILL FINALLY GET TO ENJOY MOSTLY SUNNY SKIES ON 
MONDAY...WITH TEMPERATURES MODERATING INTO THE UPPER 60S NE TO LOWER 70S
JUST ABOUT EVERYWHERE ELSE. 

EXPECT AN INCREASE IN MID/HIGH LEVEL CLOUDS LATE MONDAY NIGHT WITH
THE APPROACH OF THE TROUGH INTO THE SOUTHERN/CENTRAL APPALACHIANS.   
EARLIER ARRIVAL AND THICKER CLOUD COVER ACROSS THE WEST WILL HINDER 
RADIATIONAL COOLING AND SUPPORT SOME OF THE WARMEST OVERNIGHT 
TEMPERATURES. LOWS RANGING FROM LOWER 50S NW TO MID/UPPER 40S EAST.  
 
&&

.SHORT TERM /TUESDAY AND TUESDAY NIGHT/... 
AS OF 230 PM SUNDAY... 

SHORTWAVE ENERGY CURRENTLY IN THE CENTRAL PLAINS WILL PROGRESS 
EASTWARD THROUGH THE APPALACHIANS TO THE EASTERN SEABOARD ON 
TUESDAY...WHILE ADDITIONAL SHORTWAVE ENERGY (CURRENTLY IN FAR 
WESTERN CANADA) DIGS SOUTHEAST THROUGH THE GREAT LAKES AND INTO THE 
NORTHERN MID-ATLANTIC. AN ATTENDANT SFC LOW WILL STRENGTHEN ACROSS 
THE MID-ATLANTIC AND NEW ENGLAND ON TUE...WITH AN ASSOCIATED COLD 
FRONT APPROACHING FROM THE NW LATE TUE/TUE NIGHT. ONLY BRIEF 
MOISTURE RECOVERY IS EXPECTED IN ASSOC/W THIS SYSTEM AND SFC 
DEWPOINTS MAY STRUGGLE TO EXCEED THE 50S. HOWEVER...RELATIVELY STEEP 
MID-LEVEL LAPSE RATES AND INSOLATION MAY ALLOW FOR MARGINAL DIURNAL 
DESTABILIZATION (~500 J/KG MLCAPE) TUE AFT/EVE. GIVEN DPVA 
JUXTAPOSED WITH LOW LEVEL CONVERGENCE AND MARGINAL INSTABILITY... 
EXPECT A CHANCE OF SHOWERS AND ISOLD STORMS...THOUGH CHANCES WILL BE 
CAPPED AT 50% DUE TO UNCERTAINTY IN THE EVOLUTION OF THE UPPER LEVEL 
PATTERN AND WHETHER OR NOT THE AFOREMENTIONED FACTORS WILL BE 
FAVORABLE ALIGNED. DO NOT ANTICIPATE ANY CHANCE FOR SEVERE WEATHER 
GIVEN MARGINAL MOISTURE/INSTABILITY AND DEEP LAYER SHEAR LESS THAN 
25 KT (SUPPORTIVE OF MULTICELL ORGANIZATION)...THOUGH PERHAPS 
SLIGHTLY STRONGER (CLOSER TO 30 KT) NEAR THE VA BORDER. HIGHS TUE IN 
THE MID/UPPER 70S TO NEAR 80F IN THE FAR SE...WITH LOWS TUE NIGHT 
RANGING FROM THE UPPER 40S (N/NW) TO LOWER/MID 50S (S/SE). -VINCENT

&&

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

WED-THU: EXPECT DRY CONDITIONS TO PREVAIL IN THIS PERIOD DUE TO 
SYNOPTIC SUBSIDENCE ASSOC/W RISING HEIGHTS ATTENDANT AN UPPER LEVEL 
RIDGE BUILDING OVER THE EASTERN CONUS. EXPECT TEMPS NEAR OR SLIGHTLY 
BELOW NORMAL (HIGHS IN THE LOWER/MID 70S) ASSOC/W HIGH PRESSURE 
BUILDING INTO THE REGION FROM THE NORTH.

FRI-SUN: EXPECT SOME POTENTIAL FOR CONVECTION ACTIVITY FRI AFTERNOON 
INTO FRI NIGHT AS THE UPPER LEVEL PATTERN GRADUALLY SHIFTS TO BROAD 
CYCLONIC FLOW ALOFT IN THE PRESENCE OF A MORE SEASONABLE MOISTURE 
RETURN. AT THIS TIME...EXPECT NEAR CLIMO TEMPS AND PRECIP CHANCES IN 
ASSOC/W A RELATIVELY FLAT /UNIDIRECTIONAL/ UPPER LEVEL PATTERN OVER 
THE REGION NEXT WEEKEND. -VINCENT

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 120 PM SUNDAY...

WEDGE OF COOL DRY AIR ACROSS THE PIEDMONT WILL SECURE VFR CONDITIONS 
AT KGSO...KINT...AND KRDU THROUGH THE PERIOD...WHILE THE LOW OFF THE 
SOUTHEAST COAST WILL THREATEN TO PRODUCE PERIODS OF SUB-VFR 
CONDITIONS ACROSS EASTERN TERMINALS THROUGH MONDAY MORNING.

EXPECT PREDOMINATELY BKN VFR STRATUS LAYER BETWEEN TO 3.5-5KFT 
ACROSS EASTERN TERMINALS THROUGH 00Z IN ASSOCIATION WITH THE SLOW 
EASTWARD MOVING VERTICALLY STACKED LOW OFF THE SOUTHEAST 
COAST...WITH THE POTENTIAL FOR A BRIEF PERIOD OF MVFR CEILINGS 
ACCOMPANYING SOME OF THE LAST RAIN BANDS MOVING ONSHORE. BREEZY NELY 
WINDS WILL PERSIST AT ALL TERMINALS...GUSTING TO 25 TO 27KTS AT 
TIMES.

NAM BUFR SOUNDINGS SUGGEST THAT AS THE BOUNDARY LAYER COOLS...LOW 
STRATUS WILL BE APT TO FORM OVERNIGHT DUE TO THE RELATIVELY DEEP 
NELY ONSHORE FLOW. THE GFS IS MUCH DRIER IN THE LOWER 
LEVELS...SUGGESTING LITTLE IN THE WAY OF SUB-VFR CEILINGS. EXPECT WE 
WILL SEE AT LEAST SOME RETURN OF CLOUDS INTO THE COASTAL PLAIN...AND 
AS POSSIBLY FAR INLAND AS SAY THE EASTERN/CENTRAL PIEDMONT. WILL 
INDICATE THIS IN THE FORECAST WITH BROKEN MVFR CEILINGS AT KRWI AND 
KFAY.  

LOOKING BEYOND 12Z MONDAY MORNING... AS THE OFFSHORE LOW MOVES AWAY 
AND OUT TO SEA... VFR CONDITIONS ARE EXPECTED TO DOMINATE MONDAY AND 
MONDAY NIGHT. THE NEXT SYSTEM WILL IMPACT THE AREA ON TUESDAY... 
BRINGING ANOTHER CHANCE FOR RAIN AND ASSOCIATED ADVERSE AVIATION 
CONDITIONS. HOWEVER... THIS WILL BE A MUCH MORE PROGRESSIVE SYSTEM 
THAN THE CURRENT ONE... WITH CONDITIONS IMPROVING TO VFR LATE 
TUESDAY NIGHT INTO WEDNESDAY. VFR CONDITIONS SHOULD THEN PERSIST 
THROUGH THURSDAY AS HIGH PRESSURE RETURNS WITH THE NEXT CHANCE FOR 
SUB-VFR CONDITIONS ARRIVING BY FRIDAY AS A COLD FRONT APPROACHES 
FROM THE WEST.  

&&

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

&&

$$ 

SYNOPSIS...CBL 
NEAR TERM...CBL
SHORT TERM...VINCENT 
LONG TERM...VINCENT 
AVIATION...CBL



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