Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 040631 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 231 AM EDT WED MAY 4 2016 .SYNOPSIS...
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LOW PRESSURE AND AN ASSOCIATED TRAILING COLD FRONT WILL MOVE SLOWLY ACROSS EASTERN NC TODAY AND OFFSHORE THE MIDDLE ATLANTIC COAST THIS EVENING. MEANWHILE...A POTENT UPPER LEVEL LOW WILL AMPLIFY SOUTHEAST ACROSS THE CENTRAL APPALACHIANS AND CAROLINAS THROUGH THURSDAY...AND RESULT IN THE DEVELOPMENT OF RENEWED LOW PRESSURE...AND ASSOCIATED COOL AND UNSETTLED CONDITIONS...THAT WILL MEANDER OVER THE MIDDLE ATLANTIC REGION THROUGH THE END OF THE WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 1059 PM TUESDAY... ...SEVERE THUNDERSTORM WATCH HAS EXPIRED... A STRONG MESO-LOW OR MCV WAS TRACKING ACROSS JOHNSTON COUNTY TOWARD WILSON/WAYNE COUNTIES. THE MOVEMENT HAS BEEN ENE AT 55 TO 60 MPH AND THE REFLECTIVITY DISPLAY IS VERY IMPRESSIVE WITH THE MESO BECOMING OCCLUDED. WE MAY HAVE TO CONTINUE TO WARN DOWNSTREAM INTO THE WILSON AND GOLDSBORO AREAS BUT THE SPIN AND SEVERE THREAT SHOULD BE OUT OF THE REGION BY MIDNIGHT. RAINFALL RATES IN EXCESS OF 2 INCHES PER HOUR HAVE BEEN OCCURRING WITH THIS FEATURE. HOWEVER... THE HEAVIEST RAIN HAS BEEN LASTING AROUND 30 MINUTES DUE TO THE QUICK MOVEMENT. THIS HAS ALLOWED A BURST OF 1.5 INCHES OF RAIN IN SOME AREAS IN 20 MINUTES AND MOSTLY IN RURAL AREAS. THERE HAS BEEN SOME MINOR STREET FLOODING AROUND CLAYTON. THE QUICK MOVEMENT SHOULD PRECLUDE ANY WARNINGS FOR FLOODING. HI-RES MODELS STILL DEVELOP SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE EARLY MORNING HOURS. WITH SOME WEAK CONVECTION STILL NOTED FROM ASHEBORO TO HENDERSON... WE WILL CONTINUE TO CARRY 40-50 POP FOR SEVERAL MORE HOURS. THE GOOD NEWS IS THAT STORMS OTHER THAN THE ONE TRACKING EAST OUT OF CLAYTON TOWARD WILSON/GOLDSBORO BY 1200 AM SHOULD BE MUCH MUCH WEAKER AND SUB-SEVERE. THERE MAY BE SOME GROUND FOG LATER IF WE CAN PARTIALLY CLEAR AND DECOUPLE. LOWS GENERALLY 55-62.
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&& .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 335 PM TUESDAY... L/W TROUGH BEGINS ITS AMPLIFICATION ACROSS THE EASTERN U.S. WITH A PAIR OF DECENT S/WS DIVING SEWD ACROSS THE OH VALLEY INTO THE SE U.S. THE LEAD S/W WILL CROSS OUR REGION LATE WED AM-WED AFTERNOON...FOLLOWED BY THE OTHER WEDNESDAY EVENING. THE COOL POOL OF AIR ALOFT ASSOCIATED WITH THESE FEATURES WILL INCREASE MID LEVEL LAPSE RATES WEDNESDAY AFTERNOON AROUND 6.5 DEG C/KM. IN CONJUNCTION WITH AFTERNOON HEATING AND AVAILABLE MOISTURE...THIS SHOULD LEAD TO THE DEVELOPMENT OF LOW TOPPED CONVECTION. PLAN TO KEEP COVERAGE NO MORE THAN 40-50 PERCENT AND MAINLY LIMITED TO THE NE HALF OF THE FORECAST AREA. WITH FREEZING LEVEL BETWEEN 8500-9500 FT...CELLS THAT GROW UP TO 18K-20K FT HAVE THE POTENTIAL TO PRODUCE SMALL HAIL. SLIGHTLY COOLER HIGH TEMPS EXPECTED WEDNESDAY UNDERNEATH THE AMPLIFYING UPPER TROUGH. HIGH TEMPS LOW-MID 70S. THREAT FOR SHOWERS PERSIST INTO WEDNESDAY NIGHT WITH COVERAGE BEST IN THE NW THIRD OF THE CWA. MIN TEMPS LOW-MID 50S. && .LONG TERM /THURSDAY THROUGH TUESDAY/... AS OF 220 PM TUESDAY... A HIGHLY AMPLIFIED BUT RELATIVELY SHORT-LIVED OMEGA BLOCK WILL DEVELOP OVER THE EASTERN CONUS AS A STRONG SHORTWAVE OVER THE NORTHERN GREAT LAKES DIVES SOUTH THROUGH THE OHIO VALLEY TO BOTTOM OUT OVER ATLANTIC COAST ON THURSDAY AND FRIDAY. INITIAL SURGE OF COLD AIR ADVECTION WILL BE EARLY THURSDAY...PRODUCING SHOWERS... ESPECIALLY ACROSS THE NORTHERN TIER OF THE STATE... THURSDAY AND THURSDAY NIGHT. HIGHS THURSDAY WILL TOP OUT IN THE MID 60S ACROSS THE NORTH TO AROUND 70 SOUTHEAST. LOWS WILL BOTTOM OUT IN THE LOW TO MID 40S THURSDAY NIGHT. THE CUTOFF LOW ROTATES AROUND AND BEGINS TO LIFT OUT OF THE UPPER TROF THURSDAY NIGHT AND SHOWERS WILL BE FEWER IN NUMBER AND FOCUSED ON THE NORTHEAST FRIDAY...AND ENDING IN THE FAR NORTHEAST BY SATURDAY MORNING. HIGHS FRIDAY WILL REMAIN WELL BELOW NORMAL...FROM MID 60S ACROSS THE NORTHERN TIER TO VERY LOW 70S ACROSS THE SOUTH. A SECOND SHORTWAVE DIVING SOUTH IN THE AMPLIFIED NORTHWEST FLOW PUSHES A DRY AND WEAK FRONT BRIEFLY SOUTH OF THE AREA LATE SUNDAY. THE MAIN IMPACT FROM THIS SHORTWAVE...HOWEVER...WILL BE TO SHIFT THE OMEGA BLOCK EASTWARD...ALLOWING THE WEST RIDGE LOBE OF THE BLOCK TO EDGE EAST OVER THE AREA...WITH AN ACCOMPANYING WARMING TREND... EARLY NEXT WEEK. ALL TOLD...DRY WEATHER SATURDAY THROUGH TUESDAY WITH HIGHS WARMING FROM THE MID 70S SATURDAY TO LOWER 80S SUNDAY AND MONDAY...TO MOSTLY MID 80S TUESDAY. MORNING LOWS WILL FOLLOW THE TREND...FROM LOW 50S SATURDAY MORNING TO THE LOWER 60S BY TUESDAY MORNING. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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AS OF 230 AM WEDNESDAY... A COLD FRONT STRETCHED AT 06Z FROM A 1006 MB SURFACE LOW NEAR KIXA SOUTH SOUTHWESTWARD ALONG A KHNZ-KBUY-KAFP LINE. THE FRONT...AND FOLLOWING LIGHT NORTH TO NORTHWESTERLY WIND AND DRIER AIR IN THE LOW LEVELS...WILL CONTINUE TO SETTLE SOUTHEASTWARD ACROSS CENTRAL NC DURING THE NEXT SEVERAL HOURS. PRIOR TO THE PASSAGE OF THE FRONT...HOWEVER...PARTIAL CLEARING AND RESIDUAL LOW LEVEL MOISTURE THAT HAS BEEN AUGMENTED BY HEAVY RAIN IN MANY AREAS...WILL LEAD TO THE SHORT-LIVED OCCURRENCE OF AREAS OF FOG AND LOW CLOUDS AROUND KRDU/KFAY/KRWI. IN ADDITION...A MORE PROLONGED PERIOD OF SUB-VFR CONDITIONS --MOST LIKELY IN THE FORM OF LIFR-IFR CEILINGS-- WILL DEVELOP SOUTH OUT OF SOUTHEASTERN VA /IMMEDIATELY BEHIND AND IN PROXIMITY TO THE AFOREMENTIONED SURFACE LOW/ AND CONSEQUENTLY AFFECT KRWI THROUGH AROUND 12-13Z. ASSOCIATED CEILINGS WILL LIFT THROUGH MVFR RANGE AT KRWI AND SCATTER TO VFR BETWEEN 14-17Z. OTHERWISE...THE APPROACH OF A LEAD SHORTWAVE TROUGH/DISTURBANCE ALOFT NOW OVER THE LOWER OH AND TN VALLEYS WILL RESULT IN SCATTERED TO BROKEN HIGH-BASED STRATOCUMULUS BETWEEN 4000-8000 FT...AS WELL AS THE DEVELOPMENT...AND AT LEAST VICINITY OCCURRENCE...OF SHOWERS THIS MORNING THROUGH THE END OF THE TAF PERIOD. A FEW LIGHTNING STRIKES WILL BE POSSIBLE NEAR AND ESPECIALLY JUST EAST OF KRWI EARLY THIS AFTERNOON...AS DIURNAL HEATING WEAKLY DESTABILIZES THE ATMOSPHERE. A MUCH STRONGER UPPER LEVEL LOW...AND ASSOCIATED HIGHER PROBABILITY OF SUB-VFR CEILINGS AND SHOWERS...WILL AMPLIFY INTO NC LATE TONIGHT (JUST BEYOND THE 06Z TAF PERIOD) THROUGH THU. MULTIPLE SLOW-MOVING SURFACE WAVES OF LOW PRESSURE ARE FORECAST TO SUBSEQUENTLY DEVELOP IN THE VICINITY OF THE MIDDLE ATLANTIC COAST MID TO LATE WEEK...WITH ASSOCIATED PERIODS OF SUB-VFR CEILINGS AND SHOWERS/STORMS THAT WILL GROW IN COVERAGE AND INTENSITY WITH HEATING EACH AFTERNOON - ESPECIALLY AT EASTERN TAF SITES.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...BADGETT SHORT TERM...WSS LONG TERM...MLM AVIATION...26

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