-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 210508
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
105 AM EDT MON APR 21 2014

.SYNOPSIS...
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LOW PRESSURE OFF THE CAROLINA COAST WILL SLOWLY DRIFT
OUT TO SEA TODAY... AS HIGH PRESSURE BUILDS OVER THE SOUTHEAST
STATES. A COLD FRONT WILL CROSS THE REGION TUESDAY EVENING. HIGH
PRESSURE WILL BUILD BACK IN FOR WEDNESDAY THROUGH THURSDAY.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 740 PM SUNDAY...

THE LATEST SATELLITE AND SURFACE DATA INDICATE STRATOCUMULUS WERE
BUILDING BACK TO THE SOUTHWEST INTO THE EASTERN PIEDMONT AND
SANDHILLS. THIS PROCESS IS DUE TO THE MOIST ENE CYCLONIC LOW LEVEL
FLOW AROUND THE LOW PRESSURE JUST OFFSHORE. WE WILL UPDATE THE
FORECAST TO INDICATE CLOUDY SKIES SE... AND CLEAR NW... VARIABLY
CLOUDY IN A SMALL REGION IN THE CENTER. OTHERWISE... ONLY SLOW
MOVEMENT OF THE LOW PRESSURE SUGGESTS SLOW CLEARING FROM THE NW.
LOWS UPPER 30S TO LOWER 40S IN THE CLEAR N-NW PIEDMONT... RANGING
INTO THE MID TO UPPER 40S IN THE CLOUDY/BREEZY EASTERN ZONES.

&&

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

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.
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 /06Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
AS OF 105 AM MONDAY...

AT INT/GSO... HIGH CONFIDENCE IN VFR CONDITIONS WITH UNRESTRICTED
VSBYS AND MOSTLY CLEAR SKIES WITH LIGHT WINDS TODAY AND TONIGHT...
AS HIGH PRESSURE BUILDS OVER THE SOUTHEAST STATES AND GULF COAST. AT
RDU AND ESPECIALLY AT RWI/FAY... FORECAST IS NOT AS STRAIGHTFORWARD
DUE TO THE LINGERING EFFECTS OF THE STRONG LOW PRESSURE AREA LOCATED
OFF THE CAROLINA COAST EARLY THIS MORNING. THE MOIST FLOW FROM THE
NORTHEAST WILL CONTINUE TO BRING ATLANTIC MOISTURE INTO THE ERN
TERMINALS. CONTINUED VFR IS THE MOST LIKELY SCENARIO AT RDU... WHICH
WILL BE ON THE WESTWARD EDGE OF THE STRATUS SHIELD. HOWEVER AT
FAY/RWI... CIGS ARE LIKELY TO HOVER IN THE 3000 TO 3500 FT AGL
RANGE FROM NOW THROUGH THIS MORNING UNTIL AROUND 12Z-14Z... WHEN THE
DEPARTURE OF THE OFFSHORE LOW AND BUILDING HIGH PRESSURE WILL LEAD
TO CLEARING SKIES. FAY/RWI WILL ALSO SEE LINGERING BRISK WINDS FROM
THE NORTHEAST AND NNE WITH SPORADIC GUSTS TO 15-20 KTS UNTIL EARLY
AFTERNOON... WHEN WINDS WILL BECOME LIGHT OVER ALL OF CENTRAL NC.
HIGH CONFIDENCE IN VFR CONDITIONS AT ALL SITES FROM LATE AFTERNOON
THROUGH TONIGHT WITH ONLY HIGH CLOUDS PASSING OVERHEAD.

LOOKING BEYOND 06Z EARLY TUE MORNING: CONTINUED VFR THROUGH MUCH OF
TUE WITH SURFACE WINDS BECOMING SOUTHWESTERLY AT 8-13 KTS. A COLD
FRONT WILL PUSH TOWARD THE SOUTHEAST TUE EVENING INTO THE EARLY
OVERNIGHT... BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS
GENERATING MVFR CONDITIONS AND LOCALLY ENHANCED WIND GUSTS OVER 30
MPH. CLEARING SKIES AND VFR CONDITIONS LIKELY BEHIND THE FRONT LATE
TUE NIGHT THROUGH THU WITH HIGH PRESSURE BUILDING IN FROM THE NW.
MOIST SW FLOW RETURNS THU NIGHT... BRINGING POTENTIAL SUB-VFR CIGS
EARLY FRI MORNING... THEN MVFR CIGS WITH SCT SHOWERS ARE POSSIBLE
FRI AFTERNOON IN THE WARM SECTOR AHEAD OF AN APPROACHING FRONT. -GIH
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...HARTFIELD
NEAR TERM...BADGETT
SHORT TERM...VINCENT
LONG TERM...VINCENT
AVIATION...HARTFIELD