Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 250210 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1010 PM EDT THU APR 24 2014 .SYNOPSIS...HIGH OVER THE AREA WILL SHIFT OFFSHORE TONIGHT. A WARM FRONT WILL LIFT NORTH THROUGH NC AND VA FRIDAY MORNING...FOLLOWED BY THE PASSAGE OF A COLD FRONT FRIDAY EVENING. && .NEAR TERM /THROUGH FRIDAY NIGHT/...
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AS OF 1009 PM THURSDAY... AS OF 2Z HIGH PRESSURE HAS MOVED OFF OF THE NC COAST AND WINDS HAVE GONE CALM ACROSS MUCH OF THE CWA. IN ADDITION DEWPOINT RECOVERY HAS BEGUN WITH 40S ACROSS THE AREA AND TEMPS DROPPING INTO THE LOWER 60S AND UPPER 50S. AS THE HIGH MOVES AWAY AND A WARM FRONT LINGERS SOUTH OF THE AREA...FLOW WILL GRADUALLY MOVE FROM A MORE SOUTHEASTERLY DIRECTION AROUND THE BACK SIDE OF THE HIGH TO A SOUTHWESTERLY DIRECTION AHEAD OF THE APPROACHING COLD FRONTAL SYSTEM THAT REMAINS BACK OVER THE MISSISSIPPI VALLEY AT THIS TIME. UNTIL THEN EXPECT INCREASING CHANCES OF STRATUS...ESPECIALLY IN THE WEST WHERE MOISTURE ADVECTION WILL ARRIVE MORE QUICKLY. WHILE SOME OF THE CONVECTIVE ALLOWING MODELS HINT AT SOME SHOWER ACTIVITY PRIOR TO SUNRISE...CONFIDENCE IN THIS IS VERY LOW DUE TO THE LACK OF MOISTURE AT THE CURRENT TIME. ANY PRECIPITATION THAT DOES OCCUR WOULD BE VERY LIGHT AT BEST AND CONFINED TO THE SOUTHWESTERN PIEDMONT. LOW TEMPS IN THE UPPER 40S TO MID 50S NE TO SW. PREVIOUS DISCUSSION FOLLOWS -ELLIS FRIDAY: THE CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE THROUGH THE DAY FRIDAY...FROM WEST TO EAST...AS THE WARM FRONT LIFTS NORTHWARD AND A COLD FRONT APPROACHES FROM THE WEST. MODELS CONTINUE TO SHOW GOOD INSTABILITY OF 500-1500 J/KG AND SHEAR OF 40-50 KTS FRIDAY AFT/EVE. THE SPC HAS UPGRADED MUCH OF THE AREA TO SLIGHT RISK FOR SEVERE STORMS FOR TOMORROW AFTERNOON...WITH THE MAIN THREATS EXPECTED TO BE HAIL AND LOCALLY DAMAGING WINDS. AN ISOLATED TORNADO CANNOT BE RULED OUT...SHOULD SOME DIFFERENTIAL HEATING BOUNDARIES TO SET UP EARLY IN THE DAY. FORECAST INSTABILITY AND CYCLONICALLY CURVED FORECAST HODOGRAPHS...WITH SRH VALUES IN THE 100-300 M2/S2 RANGE WOULD ALSO SUPPORT A LOW TORNADO THREAT. OTHERWISE...EXPECT SOUTHERLY WINDS OF 10-15 KTS...GUSTING TO AROUND 20 KTS AND HIGHS IN THE MID TO UPPER 70S DURING THE DAY. FRIDAY NIGHT: AS THE COLD FRONT MOVES THROUGH AND NOCTURNAL STABILIZATION COMMENCES AFTER SUNSET...SHOULD SEE SHOWERS AND STORMS MOVE OFF TO THE EAST AND WIND SPEEDS DECREASING AND VEERING TO THE NW. CLEAR SKIES AND DRY WEATHER ARE EXPECTED BY MIDNIGHT FOR THE MAJORITY OF CENTRAL NC...AND LOWS FRIDAY NIGHT WILL BE LOWEST IN THE NW...UPPER 40S...AND HIGHEST WHERE THE FROPA AND CLEARING HAPPEN LATER...MID 50S.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 230 PM THURSDAY... FORECAST PATTERN DURING THE PERIOD WILL FEATURE A DEPARTING NORTHERN STREAM SHORTWAVE TROUGH EARLY SATURDAY WITH A SECONDARY TROUGH MOVING ACROSS THE NORTHEAST SATURDAY NIGHT. A GENERAL NORTHWEST FLOW ALOFT PERSISTS THROUGH THE PERIOD. AT THE SURFACE A WEAK AND PROGRESSIVE AREA OF HIGH PRESSURE MOVES ACROSS THE DEEP SOUTH ON SATURDAY AND THEN OFF THE SOUTHEAST COAST SATURDAY NIGHT AS A BACK DOOR COLD FRONT DROPS INTO VIRGINIA AND NORTHEAST NORTH CAROLINA LATE SATURDAY NIGHT AND EARLY SUNDAY. THE BACK DOOR COLD FRONT WILL BE THE MAIN FORECAST PROBLEM DURING THE PERIOD. GUIDANCE IS CONSISTENT IN ADVERTISING SOME GREAT WEATHER ON SATURDAY WITH A FEW PERIODS OF HIGH CLOUDS MIX WITH A GOOD DEAL OF SUNSHINE. HIGH TEMPERATURES WILL RANGE BETWEEN 78 ACROSS THE NORTHEAST AND 82 IN THE SOUTHWEST. A LIGHT WESTERLY WIND AT 5 TO 10 MPH IS EXPECTED WITH A FEW GUSTS TO 15 MPH DURING MID AFTERNOON. MID AND HIGH LEVEL MOISTURE WILL INCREASE SATURDAY NIGHT WITH PARTLY CLOUDY SKIES EXPECTED. LOWS SHOULD RANGE IN THE LOWER TO MID 50S. FORECAST CONFIDENCE DECREASES ON SUNDAY AND SUNDAY NIGHT AS THE LATEST SET OF GUIDANCE IS A LITTLE BIT MORE AGGRESSIVE IN BRINGING THE BACKDOOR FRONT INTO AT LEAST THE NORTHEAST PART OF THE ON SUNDAY CWA. THE NAM/GFS/EC ALL PUSH THE FRONT INTO AT LEAST THE NORTHERN COASTAL PLAIN AFTER MIDNIGHT MONDAY MORNING AND THEN LINGER FOR MOST OF THE DAY. STILL NOT READY TO FULLY COMMIT TO THIS SCENARIO BUT HAVE LOWERED TEMPS IN THE NORTHERN COASTAL PLAIN FOR SUNDAY AND INCREASED CLOUD COVER A BIT. SUBSEQUENT SHIFTS WILL NEED TO MONITOR THIS AND THE FORECAST IS LIKELY TO EVOLVE OVER THE COMING DAYS. HIGHS ARE NOW FORECAST TO RANGE IN THE LOWER 70S ACROSS THE NORTHEAST AND NEAR 80 IN THE SOUTHWEST. -BLAES && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 230 PM THURSDAY... AN UNSETTLED WEATHER PERIOD IS EXPECTED BEGINNING EARLY NEXT WEEK...LIKELY PERSISTING INTO THE MIDDLE/LATE PART OF THE WEEK AS A BLOCKING PATTERN SETS UP ACROSS THE CONUS. A STRONG SYSTEM/CUTOFF LOW THAT WILL LIKELY BE A BIG SEVERE WEATHER MAKER FOR THE CENTRAL CONUS OVER THE WEEKEND/EARLY NEXT WEEK....WILL SLOWLY MOVE EASTWARD AFFECTING OUR AREA MOSTLY LIKELY STARTING TUESDAY. DUE TO SIGNIFICANT MODEL SPREAD...THERE IS STILL A LOT TO BE WORKED OUT WITH REGARD TO THE DETAILS OF THIS SYSTEM...THEREFORE FORECAST UNCERTAINTY REMAINS HIGH. OVERALL WILL CONTINUE TO RAMP UP PRECIP CHANCES LATE MONDAY... WITH THE BEST TIME FRAME LOOKING TO BE TUESDAY INTO WEDNESDAY. GIVEN THE STRENGTH OF THE SYSTEM AND TIME OF YEAR...SEVERE WEATHER AND/OR HEAVY RAIN WILL BE A POSSIBILITY... ALTHOUGH EXACTLY WHEN IS TOUGH TO DETERMINE RIGHT NOW. TEMPS SHOULD BE NEAR TO SLIGHTLY BELOW NORMAL...BUT WILL ULTIMATELY DEPEND ON THE AMOUNT/TIMING OF CLOUDS/PRECIP. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 820 PM WEDNESDAY 24 HOUR TAF PERIOD: WE HAVE HIGH CONFIDENCE OF VFR CONDITIONS CONTINUING THIS EVENING INTO EARLY FRIDAY MORNING. INCREASING SOUTHERLY LOW LEVEL FLOW WILL INCREASE FRIDAY MORNING IN ADVANCE OF A COLD FRONT. THIS WILL LIKELY LEAD TO SOME SUB-VFR CIGS BY DAYBREAK AND POSSIBLY SOME ISOLATED TO WIDELY SCATTERED SHOWERS ALONG A NORTHWARD RETREATING WARM FRONT. THE HIGHEST CONFIDENCES IN SUB-VFR CONDITIONS BY AROUND DAYBREAK IS EXPECTED TO BE IN THE TRIAD REGION (KGSO/KINT)... WHERE IFR/MVFR CONDITIONS WILL BE POSSIBLE (POSSIBLY EVEN BRIEF LIFR). EXPECT ANY SUB-VFR CIGS THAT FORM ACROSS THE AREA WILL IMPROVE IN A EAST TO WEST FASHION... WITH KGSO/KINT POSSIBLY NOT RETURNING TO VFR UNTIL AFTER A BAND OF SHOWERS/STORMS CROSS THE REGION DURING THE MID TO LATE AFTERNOON. WRT THE POTENTIAL FOR SHOWERS AND STORMS... A STRONG TO SEVERE LINE OF SHOWERS AND STORMS IS EXPECTED TO CROSS THE AREA DURING THE AFTERNOON INTO THE EARLY EVENING ALONG AND OR IN ADVANCE OF A COLD FRONT. SUB-VFR CONDITIONS WITH GUSTY WINDS WILL BE POSSIBLE WITH ANY SHOWERS/STORMS FRIDAY AFTERNOON. THUS... HAVE INCLUDED A PROB30 GROUP FOR THIS TIME FRAME TO ACCOUNT FOR THE THREAT. IN ADDITION... STRENGTHENING SOUTHERLY TO SOUTHWESTERLY FLOW IN ADVANCE OF THE COLD FRONT WILL ALLOW SUSTAINED WINDS TO INCREASE INTO THE 12 TO 20 MPH RANGE IN THE AFTERNOON... WITH GUSTS OF UP TO 25 MPH (MAYBE EVEN 30 MPH LATE IN THE DAY) POSSIBLE. EXPECT THE BAND OF SHOWERS/STORMS WILL MOVE TO THE EAST OF CENTRAL NC BY EARLY FRIDAY EVENING (GENERALLY BY 00Z)... WITH THE MAIN COLD FRONT NOT MOVING THROUGH THE AREA UNTIL LATE EVENING INTO EARLY SATURDAY MORNING. LOOKING AHEAD: CONDITIONS SHOULD IMPROVE BACK TO VFR BEHIND THE FRONT FRIDAY NIGHT AND INTO SATURDAY MORNING. LIGHT WINDS AND VFR CONDITIONS WILL PREVAIL FOR THE WEEKEND. UNSETTLED WEATHER WILL RETURN AGAIN EARLY NEXT WEEK...AND WILL LIKELY LINGER THROUGH MID- WEEK. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MWS NEAR TERM...ELLIS/KC SHORT TERM...JB LONG TERM...KRD AVIATION...BSD/KC

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