Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 050647 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 245 AM EDT THU MAY 5 2016 .SYNOPSIS... DEEP LOW PRESSURE WILL WOBBLE SLOWLY EASTWARD OVER THE MIDATLANTIC REGION AND CAROLINAS THROUGH FRIDAY NIGHT... BRINGING UNSETTLED WEATHER. THIS LOW PRESSURE WILL MOVE NORTHEAST AWAY FROM THE AREA EARLY SATURDAY... BRINGING IMPROVING WEATHER FOR SATURDAY INTO SUNDAY. A COLD FRONT APPROACHING FROM THE NORTHWEST WILL STALL OUT NEAR THE VIRGINIA NORTH CAROLINA BORDER LATE SUNDAY INTO MONDAY. && .NEAR TERM /TODAY AND TONIGHT/...
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AS OF 245 AM THURSDAY... QUITE AN UNSETTLED PATTERN IS EXPECTED FOR THE NEXT 24-30 HRS... WITH A GREATER CHANCE OF PRECIP ESPECIALLY IN THE TRIANGLE AND TO THE NORTH AND EAST. THE LATEST SURFACE MAP SHOWS ONE FRONT AND LOW HEADING OFFSHORE WHILE ANOTHER FRONT AND LOW APPROACH FROM THE NW. THE MID-UPPER LEVEL VORTEX THAT WILL DRIVE OUR WEATHER FOR THE NEXT COUPLE OF DAYS IS CLEARLY NOTED ON WATER VAPOR IMAGERY OVER THE OH VALLEY AND IS POISED TO DRIFT SLOWLY SOUTHEAST TO A POSITION CENTERED OVER THE CAROLINAS TODAY... WITH MULTIPLE LOBES OF VORTICITY ROTATING ABOUT ITS CENTER. ONE SUCH WAVE IS NOW SWINGING THROUGH THE WRN PIEDMONT BRINGING A BROAD BUT BROKEN BAND OF SHOWERS INTO OUR WRN COUNTIES... FUELED IN PART BY STEEP MID LEVEL LAPSE RATES OF 6.8-7.0 C/KM ACTING ON ELEVATED PW AROUND 0.75 IN. MODELS INCLUDING CONVECTION-ALLOWING AND PARAMETERIZED ALL SHOW UPSCALE GROWTH OF THIS PRECIP AS IT SHIFTS SLOWLY EASTWARD THROUGH CENTRAL NC... CULMINATING IN A BAND OF MODERATE TO HEAVY PRECIP PIVOTING OVER THE NE CWA... SUPPORTED BY FOCUSED UPPER DIVERGENCE ATOP LOW LEVEL MASS CONVERGENCE ALONG A SURFACE TROUGH EXTENDING FROM THE JUST-OFFSHORE LOW BACK ACROSS ERN/NRN NC AND THROUGH CENTRAL VA... AS WELL AS WEAK INSTABILITY WITH DAYTIME HEATING... EXACERBATED BY MID LEVEL LAPSE RATES OF 6.5-7.5 C/KM AS THE LOW TRACKS OVER THE REGION. WITH APPARENTLY PLENTIFUL LIFT AND MOISTURE... HAVE RAISED POPS ACROSS THE BOARD... STARTING WITH CHANCE POPS MAINLY IN THE WRN HALF EARLY THIS MORNING SPREADING EASTWARD AND TRENDING UP TO CATEGORICAL NE TAPERING TO GOOD CHANCE SOUTH AND WEST (FARTHER FROM THE BEST STACKED FORCING FOR ASCENT) FOR THE AFTERNOON INTO THE NIGHT. WHILE ANY INSTABILITY IS APT TO DECREASE AFTER NIGHTFALL... OTHER MECHANISMS FOR FORCING LIFT PERSIST... INCLUDING MID LEVEL DPVA AS WAVES ROTATE AROUND THE LOW AND LOW LEVEL CONFLUENT FLOW ALONG THE PERSISTENT TROUGH. SUCH AN EXTENDED PERIOD OF A FOCUSED MODERATE TO HEAVY RAIN OVER THE NE CWA WOULD BRING ABOUT CONCERN FOR FLOODING... HOWEVER FLASH FLOOD GUIDANCE IS RATHER HIGH HERE (2.5- 3.5" IN 3 HRS)... SUGGESTING MORE OF AN URBAN AND SMALL STREAM FLOOD THREAT. AS SUCH... WILL NOT ISSUE A FLASH FLOOD WATCH... BUT WILL KEEP A CLOSE EYE ON THIS POTENTIAL THROUGH TODAY. THICKNESSES WILL BE HELD DOWN BY CONSIDERABLE CLOUD COVER THROUGH MUCH OF THE DAY AND COLD AIR ADVECTION WITH PERIODS OF SHOWERS... SO EXPECT CHILLY WELL- BELOW-NORMAL HIGHS IN THE UPPER 50S TO LOWER 60S ALONG/NORTH OF HIGHWAY 64 WITH MID 60S SOUTH WHERE PRECIP WILL BE MORE PATCHY AND LIGHTER. LOWS TONIGHT IN THE MID 40S TO AROUND 50. -GIH
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&& .SHORT TERM / /...
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AS OF 245 AM THURSDAY... TO BE UPDATED SHORTLY.
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&& .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 230 PM WEDNESDAY... COOL POOL ALOFT WILL MAINTAIN MID LEVEL INSTABILITY WITH LAPSE RATES GREATER THAN 6C/KM...BUT THUNDER WILL BE DAMPENED BY WEAK SHEAR PROFILE AND MINIMAL DIFFLUENCE ALOFT. EXPECT WRAP AROUND SHOWERS TO DEVELOP AND STREAM SOUTH INTO THE AREA THROUGH MUCH OF THE DAY AS THE CUTOFF LOW LIFTS NORTH...WITH COVERAGE AT A MINIMUM OVER THE SOUTHWEST AND WILL BE PROGRESSIVELY DIMINISHING THROUGHOUT THE DAY IN THE NORTHEAST. TEMPS WILL BE COOL WITH CLOUD COVERAGE AND COLD RAIN...WILL STALL IN THE MID 60S OVER MOST OF THE AREA. LINGERING SHOWERS WILL END IN THE FAR NORTHEAST BY MIDNIGHT WITH MINS AROUND 50 SATURDAY MORNING. THE LARGER UPPER TROF WILL SLOWLY MOVE EAST OF THE ATLANTIC COAST THROUGH LATER SATURDAY WITH DECREASING CLOUDINESS ASSOCIATED WITH THE EXITING CUTOFF LOW LINGERING IN THE EAST INTO AFTERNOON. HIGHS WILL BENEFIT FROM A LITTLE MORE SUN AND RISING HEIGHTS BEHIND THE LOW...WITH HIGHS MOSTLY IN THE MID 70S. A DRY BACKDOOR FRONT WILL BE SAGGING SOUTH ON SUNDAY...WHERE IT WILL STALL IN THE VICINITY OF THE NC/VA BORDER AS IT ALIGNS PARALLEL TO THE PREVAILING FLOW. A FEW SHOWERS COULD FORM ALONG THE FRONTAL ZONE ACROSS THE NORTHERN COUNTIES...BUT NOT CONFIDENT ENOUGH TO PAINT THEM IN YET. CLOUDINESS WILL BE THE MAJOR IMPACT AS DOWNSLOPE FLOW WILL AID IN BOOSTING HIGHS TO NEAR 80. THE FRONT WILL BE EDGED NORTH OF THE AREA AS WE TRANSITION TO A RETURN FLOW REGIME WITH WEAK RIDGING ALOFT ASSISTING A MILD WARMING TREND MONDAY THROUGH WEDNESDAY. HIGHS AROUND 80 MONDAY WILL WARM TO THE LOW AND MID 80S BY WEDNESDAY. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 150 AM THURSDAY... CONFIDENCE IS GROWING THAT WE`LL SEE DETERIORATING AVIATION CONDITIONS THIS MORNING AT ALL SITES... WITH MVFR TO IFR CONDITIONS DOMINATING THROUGH MUCH OF THIS AFTERNOON AND INTO TONIGHT. A STRONG UPPER LEVEL LOW WILL DROP FROM THE OH VALLEY SE TO OVER NC TODAY... WITH ACCOMPANYING LOW PRESSURE AT THE SURFACE. IN THE EAST... IFR TO LIFR STRATUS AND MVFR WILL CONTINUE SPREADING INTO RWI AND NEARING RDU/FAY AS WELL IN THE PREDAWN HOURS. AND IN THE WEST... A BAND OF SHOWERS WILL MOVE INTO THE INT/GSO VICINITIES THIS MORNING BEFORE SPREADING SLOWLY EASTWARD TO THE REMAINING TAF SITES THROUGH THE LATE MORNING AND AFTERNOON. RDU AND RWI HAVE THE GREATEST CHANCE OF SEEING PROLONGED SUB-VFR CONDITIONS TODAY WITH PERIODS OF SHOWERS GENERATING MOSTLY MVFR VSBYS WITH IFR CIGS. A COUPLE OF THUNDERSTORMS ARE ALSO POSSIBLE THIS AFTERNOON AT ALL SITES... HOWEVER COVERAGE SHOULD BE LOW AND TIMING IS TOO UNCERTAIN TO INCLUDE IN THE FORECASTS AT THIS TIME. THE RAIN IS EXPECTED TO TAPER DOWN FROM SW TO NE THROUGH THE EVENING... HOWEVER RAIN WITH MVFR TO IFR VSBYS SHOULD REMAIN DOMINANT AT RDU/RWI WITH SUB-VFR CIGS PERSISTING THROUGH THE END OF THE FORECAST PERIOD. LOOKING BEYOND 06Z EARLY FRI MORNING... RDU/RWI SHOULD REMAIN IFR/LIFR UNTIL MID MORNING FRI... HOWEVER INT/GSO/FAY ARE EXPECTED TO SLOWLY IMPROVE TO MVFR. ALL SITES SHOULD BE VFR (OR HIGH-END MVFR AT WORST) BY LATE MORNING FRI... ALTHOUGH THE CHANCE REMAINS FOR BRIEF SUB-VFR CONDITIONS IN SHOWERS FRI AFTERNOON. VFR CONDITIONS SHOULD PREVAIL FRI NIGHT THROUGH MON AS THE LOW MOVES AWAY FROM THE REGION. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM... LONG TERM...MLM AVIATION...HARTFIELD

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