Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 030547 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 147 AM EDT THU SEP 3 2015 .SYNOPSIS...
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A DISTURBANCE ALOFT WILL CROSS EASTERN PORTIONS OF CENTRAL NC THIS MORNING. A LEE TROUGH WILL OTHERWISE LINGER OVER CENTRAL NC UNTIL A BACK DOOR COLD FRONT MOVES SOUTHWEST ACROSS THE AREA LATE FRI AND FRI NIGHT.
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&& .NEAR TERM /THROUGH TONIGHT/... AS OF 1000 PM WEDNESDAY... WATER VAPOR SATELLITE IMAGERY DEPICTS A WELL-DEFINED SHORTWAVE TROUGH OVER CENTRAL VA THIS EVENING. THIS FEATURE EARLIER FORCED SCATTERED TO NUMEROUS SHOWERS AND STORMS OVER VA...WHICH HAVE SUBSEQUENTLY PROPAGATED GENERALLY SOUTHEASTWARD INTO THE NORTHERN NC PIEDMONT AND COASTAL PLAIN. THE ASSOCIATED OUTFLOW BOUNDARY STRETCHED AT 0145Z FROM NEAR KBUY TO KRDU TO KASJ. WHILE SHOWERS HAVE PERCOLATED ALONG THE LENGTH OF THE BOUNDARY...THE ORIENTATION OF SHEAR VECTORS (FROM THE NW) RELATIVE TO THE BOUNDARY HAVE FOCUSED STRONG AND SUSTAINED CONVECTIVE MAINTENANCE ALONG THE SE-FACING OUTFLOW FLANK...AND THIS PROCESS WILL CONTINUE AND FAVOR FAR EASTERN HALIFAX AND EDGECOMBE COUNTIES FOR THE STRONGEST CONVECTION DURING THE NEXT HOUR. OTHERWISE...SCATTERED OR WIDELY SO SHOWERS AND ISOLATED THUNDER WILL OCCASIONALLY PERCOLATE...ALONG OUTFLOW...SOUTHEASTWARD WITH THE PASSAGE OF THE AFOREMENTIONED SHORTWAVE TROUGH AND ASSOCIATED FORCING FOR ASCENT AS IT CONTINUES SOUTHEASTWARD TOWARD THE PAMLICO SOUND BY 12Z - TIMING WHICH SHOULD RESULT IN RAIN CHANCES MOVING SOUTHEAST OF THE RAH CWFA BY AROUND 09Z. PERSISTENCE LOWS IN THE UPPER 60S TO LOWER 70S. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... AS OF 333 PM WEDNESDAY... THE MID LEVEL VORTICITY MAX SHOULD BE SHIFTING OFF THE NRN NC COAST THU MORNING... ALBEIT WITH A WEAK TRAILING SHEAR AXIS EXTENDING BACK ACROSS THE NRN CWA. THIS TRAILING VORTICITY WILL SINK SLOWLY SOUTHWARD THROUGH THE DAY BUT REMAIN EXTENDED ACROSS THE SRN CWA LATE THU THROUGH THU NIGHT. PW VALUES WILL HAVE FALLEN WITH A SLIGHTLY MORE STABLE AND SUBSIDING COLUMN BEHIND THE CORE OF THE EXITING WAVE... SO EXPECT ANY SHOWER/STORM COVERAGE TO BE FAIRLY SMALL GIVEN THE WEAK WIND FIELD... LACK OF STRONG FORCING FOR ASCENT... AND LIMITED CAPE. WILL RETAIN AN ISOLATED POP JUST ACROSS THE SOUTH AND SE NEAR THE SHEAR AXIS AND WHERE LOW LEVEL DEWPOINTS WILL LIKELY BE HIGHER. ANOTHER MUCH WEAKER WAVE WILL PUSH INTO THE REGION FROM THE SW LATE THU INTO THU NIGHT... BUT THIS APPEAR TO CONTRIBUTE VERY LITTLE DYNAMIC FORCING... AND WITH LACK OF HEATING AFTER SUNSET... COVERAGE SHOULD BE ISOLATED AT BEST WITH THIS SECOND WAVE. WILL KEEP A MENTION OF ISOLATED STORMS IN THE NE CWA THROUGH THE EVENING... THEN TREND POPS DOWN BELOW 15% OVERNIGHT. THIS PATTERN CORRELATES WITH THE LOCATION OF THE SREF`S HIGHER CHANCES OF MEASURABLE PRECIP. WITH GOOD MIXING AND CONTINUED ABOVE NORMAL THICKNESSES... EXPECT STEAMY HIGHS OF 90-95. LOWS 67-72 UNDER PARTLY CLOUDY SKIES. -GIH && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AS OF 315 PM WEDNESDAY... THE MAIN PLAYER IN THE WEATHER PATTERN FOR THE LONG TERM WILL BE A 1026 MB SURFACE HIGH PRESSURE SYSTEM OVER NEW ENGLAND THAT WILL PUSH A BACKDOOR COLD FRONT THROUGH THE AREA ON FRIDAY NIGHT AND SET UP A WEDGE FRONT THAT IN PATTERN WILL BE REMINISCENT OF A COLD AIR DAMMING SCENARIO BUT WITHOUT THE ISENTROPIC LIFT THAT WE USUALLY SEE CONTRIBUTING TO MORE STRATIFORM RAIN ACROSS THE TRIAD. THE FEATURE THROUGH WILL CAUSE LOW CLOUDS TO SPREAD ACROSS MUCH OF THE AREA ON SATURDAY AND BRING IN MUCH COOLER HIGH TEMPERATURES (LOW TO MID 80S). AS THE WEEKEND CONTINUES...A VERY WEAK LOW OFF OF THE FLORIDA COAST WILL ATTEMPT TO HELP FORM AN INVERTED TROUGH ALONG THE CAROLINA COAST BUT THE STRENGTH OF THIS FEATURE REMAINS UNCERTAIN AT THIS TIME. CURRENT MODEL RUNS SUGGEST THAT THIS FEATURE MAY REMAIN FAIRLY WEAK BUT IT WILL CERTAINLY CAUSE AN UPTICK IN POPS ACROSS EASTERN PORTIONS OF THE CWA...PARTICULARLY SUNDAY AND MONDAY AFTERNOONS DURING PEAK HEATING WITH PSEUDO WEDGE FRONT BOUNDARY HELPING TO INITIATE CONVECTION. THE EXACT LOCATION OF THIS BOUNDARY IS TO BE DETERMINED AND THUS THE AFTERNOON FORECAST REMAINS FAIRLY LOW CONFIDENCE BUT GENERAL TRENDS SUGGEST THAT RAIN WILL BE MORE LIKELY FURTHER EAST. ON TUESDAY THE SURFACE HIGH BREAKS DOWN AND TEMPERATURES WILL START A SLOW WARMING TREND INTO THE MID TO UPPER 80S BY MID WEEK. THE MAIN THREAT FOR PRECIPITATION WILL BE WITH A FEW SHORTWAVES ALONG THE SOUTH CAROLINA COAST WHICH MAY PROVIDE SOME FORCING FOR DIURNAL SHOWERS OR STORMS BOTH DAYS. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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AS OF 145 AM THURSDAY... AND AREA OF SCATTERED TO NUMEROUS SHOWERS AND STORMS HAS PUSHED TO THE EAST AND SOUTH OF ALL CENTRAL NC TAF SITES EXCEPT KFAY. HOWEVER... THE GREATEST COVERAGE AND INTENSITY SHOULD REMAIN TO THE EAST OF KFAY THIS MORNING. THUS... WILL JUST INCLUDE A TEMPO FOR SHOWERS IN THE 06-08Z TIME FRAME AT KFAY. WRT OF ANY SUB-VFR CONDITIONS THIS MORNING... EXPECT ANY SUB-VFR CONDITIONS SHOULD BE ACROSS THE EASTERN TAF SITES... WITH THE GREATEST PROBABILITY OF OCCURRENCE AT KRDU AND KRWI (WHERE CONVECTION OCCURRED YESTERDAY EVENING AND THIS MORNING)... WITH KRWI POSSIBLY SEEING SOME IFR/LIFR FOG AND LOW STRATUS. ANY SUB-VFR CONDITIONS SHOULD QUICKLY DIMINISH BY 13Z... WITH VFR CONDITIONS GENERALLY EXPECTED FOR THE REMAINDER OF THE TAF PERIOD... WITH ONLY A VERY SMALL CHANCE OF SEEING ANY ISOLATED SHOWERS AND/OR STORMS ACROSS CENTRAL NC TODAY. LOOKING AHEAD: CONVECTION WILL BE POSSIBLE IN ASSOC/W A COLD FRONTAL PASSAGE ON FRIDAY. HIGH PRESSURE WILL EXTEND INTO THE REGION FROM THE N/NE IN THE WAKE OF THE FRONT...RESULTING IN A SYNOPTIC PATTERN REMINISCENT OF COLD AIR DAMMING. AS A RESULT...SUB-VFR CEILINGS WILL BE POSSIBLE AT ALL TERMINALS OVER THE WEEKEND. -VINCENT
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...77/26 NEAR TERM...26 SHORT TERM...HARTFIELD LONG TERM...ELLIS AVIATION...BSD/VINCENT

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