Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 270700 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 300 AM EDT WED MAY 27 2015 .SYNOPSIS...BERMUDA HIGH PRESSURE CENTERED OVER THE WESTERN ATLANTIC WILL PREVAIL THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM WEDNESDAY... STRONG MID/UPPER LEVEL RIDGE OFF THE EASTERN SEABOARD MAY WEAKEN A BIT WHILE DRIFTING EVER SO SLIGHTLY EASTWARD. MEANWHILE...BERMUDA HIGH PRESSURE OVER THE WESTERN ATLANTIC WILL KEEP A WARM HUMID AIRMASS IN PLACE. SHORTWAVE ENERGY EMBEDDED IN THE SOUTHWEST FLOW ALOFT AND SEASONABLY MOIST PWATS OF 1.5-1.6"(~80TH PERCENTILE) WILL SUPPORT SCATTERED CONVECTION AS HEATING WILL STEEPEN LOW-LEVEL LAPSE RATES DURING THE DAY. ADDITIONALLY...LEFT-OVER OUTFLOW BOUNDARY FROM WEAKENING CONVECTION CURRENTLY OVER THE WESTERN PIEDMONT MAY ALSO SERVE AS A FOCUS FOR CONVECTIVE INITIATION LATER TODAY. AS SUCH...POPS WILL BE MARGINALLY HIGHER THAN THE PAST FEW DAYS... AND PERHAPS MORE EQUITABLE RAIN CHANCES FOR THE CENTRAL PIEDMONT...WITH NEARBY UPPER RIDGE LIMITING RAIN/CONVECTIVE CHANCES IN THE EAST. WEAK/MARGINAL ML CAPE BETWEEN 500-800J/KG COUPLED WITH DEEP LAYER SHEAR OF 10-15KTS WILL FAVOR DISORGANIZED CONVECTION WITH LITTLE TO NO SEVERE THREAT. TEMPERATURES...WITH PWATS CREEPING UP TODAY...EXPECTED INCREASE IN CLOUD COVER AND SLIGHTLY BETTER RAIN CHANCES MAY KNOCK A DEGREE OR TWO OFF OF YESTERDAYS READINGS. HIGHS IN THE LOWER TO MID 80S NORTHWEST TO MID/UPPER 80S SOUTHEAST. LOWS IN THE MID TO UPPER 60S. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... AS OF 300 AM WEDNESDAY... MID AND UPPER-LEVEL FLOW BECOMES INCREASINGLY MORE WESTERLY ON THURSDAY AS THE SHORTWAVE TROUGH OVER THE LOWER GREAT LAKES PROGRESSES EASTWARD INTO SOUTHERN NEW ENGLAND THROUGHOUT THE DAY. IN RESPONSE...MODELS HINT AT WEAK LEE-SIDE TROUGHINESS DEVELOPMENT ACROSS THE WESTERN PIEDMONT...WHILE DRIFTING THE LINGERING VORTICITY SHEAR AXIS EASTWARD INTO THE COASTAL PLAIN. WITH CONTINUED SEASONABLY MOIST AIR IN PLACE...THESE TWO FEATURES ALONG WITH DIURNAL DESTABILIZATION WILL SERVE AS A FOCUS FOR SCATTERED CONVECTION THURSDAY AFTERNOON/EARLY EVENING. PERSISTENCE TEMPERATURE FORECAST WILL BE FOLLOWED. HIGHS 83 TO 88. LOWS IN THE MID TO UPPER 60S. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 210 PM TUESDAY... THE UPPER RIDGE OFF THE EAST COAST WILL THEN REBUILD OVER THE SOUTHEAST COASTAL REGION FRIDAY THROUGH THE WEEKEND...AND SHOULD HELP LIMIT THE COVERAGE OF SHOWER/TSTM ACTIVITY OVER OUR AREA FRIDAY AND SATURDAY. A COLD FRONT CROSSING THE MIDWEST ON FRIDAY IS PROGGED BY THE LATEST GFS TO DROP SOUTH ACROSS OUR AREA BY SUNDAY AND DISSIPATE OVER US BY MONDAY. DESPITE THE LIFT PROVIDED BY THIS FRONT...MODELS SUGGEST THE AFOREMENTIONED RIDGE OVER THE SOUTHEAST WILL KEEP THE BULK OF THE MOISTURE JUST TO OUR NORTH. NEVERTHELESS...THERE`S ENOUGH FORCING AND MOISTURE TO WARRANT A DECENT CHANCE POP ACROSS OUR AREA LATE IN THE WEEKEND INTO EARLY NEXT WEEK. AS FOR TEMPS...PERSISTENCE IS THE BEST FORECAST AT THIS POINT WITH LITTLE CHANGE IN THE AIRMASS. HIGHS IN THE MID TO UPPER 80S AND LOWS IN THE MID 60S EACH DAY DURING THE PERIOD. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 140 AM WEDNESDAY... CONVECTION ACROSS THE WESTERN PIEDMONT CONTINUES TO WEAKEN...AND SHOULD DIMINISH OVER THE NEXT HOUR OR TWO WITH NO FURTHER AVIATION IMPACTS AT KGSO...KINT OR KRDU. SOUTH-SOUTHEASTERLY RETURN FLOW AROUND BERMUDA HIGH PRESSURE OVER THE WESTERN ATLANTIC WILL MAINTAIN A MOIST LOW-LEVEL FEED OVER THE AREA...CREATING FAVORABLE CONDITIONS FOR THE DEVELOPMENT OF SUB-VFR STRATUS AT ALL TAF SITES BETWEEN 06 TO 14Z. BY 15 TO 16Z...ANY SUB-VFR CEILINGS SHOULD LIFT TO VFR. MAINLY DIURNAL ISOLATED TO SCATTERED SHOWERS AND STORMS ARE EXPECTED THIS AFTERNOON. BUT THIS PROBABILITY APPEARS TOO LOW TO MENTION IN THE TERMINAL FORECAST AT THIS TIME. BEYOND THE 00Z VALID TAF PERIOD...THE THREAT FOR RESTRICTIONS IN EARLY MORNING FOG/STRATUS WILL CONTINUE THE WEEKEND AS BERMUDA HIGH PRESSURE HOLDS OVER THE AREA. ISOLATED TO SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS ARE EXPECTED AGAIN ON THURSDAY. RAIN CHANCES WILL BEGIN TO INTO THE WEEKEND AS UPPER LEVEL RIDGE RETROGRADES WEST OVER THE AREA. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL SHORT TERM...CBL LONG TERM...RAH AVIATION...CBL

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