Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 202342 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 740 PM EDT SUN APR 20 2014 .SYNOPSIS...WHILE LOW PRESSURE DRIFTS OUT TO SEA...HIGH PRESSURE WILL EXTEND DOWN THE EAST COAST THROUGH MON NIGHT. A LEE TROUGH WILL DEVELOP OVER THE MIDDLE ATLANTIC PIEDMONT TUE...AHEAD OF A COLD FRONT THAT WILL CROSS OUR REGION TUE NIGHT. && .NEAR TERM /THROUGH TONIGHT/...
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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.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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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
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&& .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 /00Z MONDAY THROUGH FRIDAY/... AS OF 730 PM SUNDAY... OFFSHORE LOW PRESSURE WILL MAINTAIN CONTINUED NORTHEASTERLY FLOW OVER CENTRAL NC...BREEZIEST AND MOST MOIST OVER THE COASTAL PLAIN...THROUGH EARLY MONDAY. VFR CONDITIONS THIS EVENING...RANGING FROM CLEAR SKIES AT TRIAD TERMINALS; TO 5000-6000 FT CEILINGS AT RDU; TO 3500-5000 FT CEILINGS AT RWI AND FAY...WILL PREVAIL THROUGHOUT THE TAF PERIOD...WITH ONE EXCEPTION. CEILINGS WILL LIKELY LOWER INTO IFR-MVFR RANGE LATE TONIGHT-EARLY MON AT RWI AND POSSIBLY AS FAR WEST AS FAY...AS THE RESIDUALLY MOIST LOW LEVELS OVER EASTERN NC NOCTURNALLY COOL. OTHERWISE...THE NORTHEASTERLY FLOW WILL GRADUALLY SUBSIDE...PARTICULARLY MIDDAY MON ONWARD...AS THE OFFSHORE LOW MOVES AWAY AND LOSES INFLUENCE OVER THE CAROLINAS. OUTLOOK: THE PASSAGE OF A COLD FRONT WILL RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS - AND ASSOCIATED BRIEF SUB-VFR CONDITIONS - TUE AFTERNOON AND EVENING...FOLLOWED BY BREEZY POST-FRONTAL NORTHWESTERLY WINDS WED. ANOTHER COLD FRONT WILL PROVIDE A CHANCE OF SHOWERS AND STORMS AGAIN ON FRI. && && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT SHORT TERM...VINCENT LONG TERM...VINCENT AVIATION...MWS/CBL

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