Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 010721 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 320 AM EDT MON SEP 1 2014 .SYNOPSIS...THE REGION WILL REMAIN UNDER THE INFLUENCE OF HIGH PRESSURE THROUGH MIDWEEK. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 305 AM MONDAY... BERMUDA HIGH PRESSURE WILL CONTINUE TO SUPPLY A WARM AND HUMID SOUTHERLY FLOW TODAY...WITH WEAK SOUTHWESTERLY FLOW ALOFT. THE H85 THERMAL RIDGE...WITH TEMPS AROUND 20C...SHIFTS OVER THE PIEDMONT...AND LOW-LEVEL THICKNESSES ARE FORECAST TO START OUT AROUND 1420M...ABOUT 10M HIGHER THAN SUNDAY MORNING. STATISTICAL AGREEMENT IS IN PRETTY GOOD AGREEMENT WITH MID 90S AROUND ALL OF CENTRAL NC. THE LEE/THERMAL TROUGH SHOULD SHARPEN AND DEWPOINTS SHOULD MIX OUT MORE IN THE WEST WITH A LITTLE MORE WESTERLY WIND...BUT TO THE EAST DEWPOINTS WILL BE IN THE UPPER 60S AND LOWER 70S...WHICH WILL PUSH HEAT INDICES UP AROUND 100F. A WEAK WAVE OVER WEST VIRGINIA..NOTED IN WATER VAPOR IMAGERY THIS MORNING...SHOULD PASS OFF TO THE NORTH OF THE AREA TODAY...LEAVING THE SEABREEZE AND/OR DIFFERENTIAL HEATING AS THE MAIN TRIGGERS FOR CONVECTION THIS AFTERNOON. WILL INCLUDE A CHANCE POP ACROSS THE SANDHILLS AND SOUTHERN COASTAL PLAIN WHERE MODEST MLCAPE OF 1500 J/KG IS FORECAST TO DEVELOP. OTHERWISE JUST A SLIGHT CHANCE ACROSS THE WEST. CONVECTION WILL BE DIURNALLY DRIVEN AND WILL COME TO AN END EARLY THIS EVENING. STRATUS WILL BE POSSIBLE AGAIN..WITH GUIDANCE AGAIN POINTING TO THE COASTAL PLAIN. LOWS IN THE UPPER 60S AND LOWER 70S.
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&& .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
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AS OF 315 AM MONDAY... HOT AND HUMID CONDITIONS CONTINUE ON TUESDAY...WITH H85 TEMPS AGAIN AROUND 20C AND SOUTHERLY FLOW AROUND THE BERMUDA HIGH. A SHORTWAVE CROSSING THE GREAT LAKES WILL LEAD TO SOME VERY WEAK HEIGHT FALLS OVER VIRGINIA AND NC...WHICH SHOULD INCREASE CONVECTIVE COVERAGE AMIDST MLCAPE OF 1000-2000 J/KG AND PW OVER 1.75 INCHES. SHEAR IS FORECAST TO REMAIN RELATIVELY WEAK...HOWEVER...AND THE BETTER SEVERE THREAT SHOULD ACCORDINGLY REMAIN TO OUR NORTH. HIGHS IN THE MID 90S AND HEAT INDICES AROUND 100F IN THE EAST. THE WEAK HEIGH FALLS ALOFT AND LINGERING OUTFLOW BOUNDARIES MAY HELP MAINTAIN SOME SHOWERS/STORMS INTO THE OVERNIGHT HOURS TUESDAY NIGHT...WITH MOST ACTIVITY DWINDLING AFTER MIDNIGHT. LOWS IN THE UPPER 60S AND LOWER 70S.
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 250 AM MONDAY... A HOT SUB-TROPICAL RIDGE OVER THE SOUTHEAST WILL WAX AND WANE THROUGHOUT THE FORECAST PERIOD. AFTER PEAKING OVER THE SE EARLY THIS WEEK...THE RIDGE WILL BRIEFLY RETREAT WEST AND YIELD TO A GENERALLY E-W ORIENTED MID LEVEL SHEAR AXIS FORECAST TO DRIFT SOUTH INTO THE CAROLINAS WED-THU...BEFORE EXPANDING NORTHWARD ONCE AGAIN...INTO THE OH VALLEY AND MIDDLE ATLANTIC...FRI-SAT. MEDIUM RANGE ENSEMBLE GUIDANCE SUGGESTS THIS TREND WILL CONTINUE INTO NEXT WEEK...WITH BRIEF WEAKENING OF THE SUB-TROPICAL RIDGE SUN-MON...AT THE BASE OF A PROGRESSIVE NORTHERN STREAM TROUGH FORECAST TO CROSS SE CANADA... ONLY TO RE-EXPAND THROUGH MID WEEK. THE EBB AND FLOW OF THE PATTERN ALOFT...AND ASSOCIATED PERIODIC RELAXATION OF THE SUB-TROPICAL RIDGE...WILL ALLOW A PAIR OF COLD FRONTS TO SETTLE INTO NC - ONE WED INTO THU AND THE OTHER SAT NIGHT- SUN. BOTH MODEST COOLING AND ABOVE AVG PRECIPITATION CHANCES WILL OCCUR DURING THESE TIMES...IN CONTRAST TO OTHERWISE HOT CONDITIONS IN THE LOWER TO MIDDLE 90S...WITH DIURNALLY; PIEDMONT, AND SEA- BREEZE-DRIVEN CONVECTION. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 130 AM MONDAY... SOUTHERLY FLOW CONTINUES AROUND THE BERMUDA HIGH...WHICH WILL LIKELY LEAD TO THE DEVELOPMENT OF STRATUS AGAIN LATE TONIGHT. THE NC COASTAL PLAIN IS THE FAVORED AREA FOR MVFR TO POSSIBLY IFR CEILINGS...ESPECIALLY FROM KFAY NORTH TO KRWI AFTER 08Z. VFR CONDITIONS ARE EXPECTED TO RETURN AFTER SUNRISE...WITH ISOLATED SHOWERS/STORMS POSSIBLE THIS AFTERNOON...WITH THE BEST CHANCE AT KFAY AFTER 18Z. OUTLOOK... BRIEF RESTRICTIONS IN DIURNAL CONVECTION ARE POSSIBLE EACH AFTERNOON...WITH RESTRICTIONS IN LOW CLOUDS AND FOG DURING THE PRE-DAWN MORNING HOURS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...SEC NEAR TERM...BLS SHORT TERM...BLS LONG TERM...MWS AVIATION...SEC/BLS

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