Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 312309 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 708 PM EDT THU JUL 31 2014 .SYNOPSIS... COOL HIGH PRESSURE WILL LINGER OVER THE AREA TODAY. THE REMAINS OF A STATIONARY FRONT WILL LIFT NORTH AS A COASTAL TROUGH ON FRIDAY THEN STALL OVER THE AREA DURING THE WEEKEND. THIS WILL BRING GOOD RAIN CHANCES...WITH PERIODS OF HEAVY RAINFALL POSSIBLE...FRIDAY THROUGH MONDAY. MORE SEASONABLE WEATHER WILL DEVELOP THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 730 PM THURSDAY...A 500 MB TROUGH REMAINS IN PLACE FROM THE GREAT LAKES TO THE CENTRAL GULF COAST. EAST WINDS AT THE SURFACE... PRODUCED BY THE FLOW BETWEEN A FRONT STALLED OFFSHORE AND WEAK HIGH PRESSURE OFF THE MID-ATLANTIC COAST...VEER WITH HEIGHT. THIS IS ADVECTING ATLANTIC MOISTURE INTO EASTERN SC/NC WITHIN THE 925-750 MB LAYER...WITH WINDS VEERING TO THE SOUTHWEST AT 500 MB AND ABOVE AHEAD OF THE LONGWAVE TROUGH. WERE IT NOT FOR A LAYER OF QUITE DRY AIR BETWEEN 750 MB AND 550 MB (APPROXIMATELY 8000-17000 FT AGL) THIS COULD BE AN IDEAL SETUP FOR HEAVY RAINFALL. THIS DRY AIR SHOULD HELP REDUCE RAINFALL RATES THROUGH MIDNIGHT. AN UPPER LEVEL DISTURBANCE DISCERNIBLE IN WATER VAPOR IMAGERY JUST NORTH OF ATLANTA WILL MOVE NORTHEASTWARD AND INTO NORTH CAROLINA OVERNIGHT. FOR THE SECOND NIGHT IN A ROW MODELS ARE SHOWING MODEST ISENTROPIC LIFT DEVELOPING ALONG THE 305K THETA SURFACE...LIKELY ASSISTING THE DEVELOPMENT OF SHOWERS. THE BEST POTENTIAL FOR SHOWER ACTIVITY IS EXPECTED ALONG THE INTERSTATE 95 CORRIDOR WHERE I HAVE INCREASED POPS INTO THE 60-100 PERCENT RANGE. ALONG THE COAST (ESPECIALLY NORTH OF MYRTLE BEACH IN WILMINGTON) DRY MID-LEVEL AIR SHOULD MAINTAIN DRY CONDITIONS THROUGH MIDNIGHT...BUT INCREASING MOISTURE AFTER MIDNIGHT MAY ALLOW SHOWERS TO DEVELOP DOWN HERE EVENTUALLY AS WELL. POPS IN THE 30-40 PERCENT RANGE ARE FORECAST HERE...MAINLY LATE. LOWS SHOULD FALL TO 70-72 INLAND...WITH MID 70S AT THE BEACHES WITH ONSHORE WINDS.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 230 PM THURSDAY...PERIOD CONTINUES TO LOOK UNSETTLED WITH INCREASING DEEP MOISTURE AND DEVELOPING LOW LEVEL CONVERGENCE. MID LEVEL TROUGH HANGING OVER THE EASTERN CONUS THE PAST SEVERAL DAYS STARTS TO WEAKEN AND SHIFT WEST AS 5H RIDGE OVER THE WESTERN ATLANTIC EXPANDS. MEANWHILE AT THE SURFACE WESTERN ATLANTIC HIGH WILL EXTEND WEST...PUSHING FRONT STALLED OFF THE COAST INTO THE REGION. DEEP SOUTHWEST FLOW...TAPPING GULF MOISTURE...COMBINED WITH LOW LEVEL SOUTHEAST FLOW...TAPPING ATLANTIC MOISTURE...WILL PUSH PRECIPITABLE WATER VALUES TO AND ABOVE 2 INCHES FOR MUCH OF THE PERIOD. DIVERGENT FLOW ALOFT AND LOW LEVEL CONVERGENCE ALONG THE QUASI-STATIONARY BOUNDARY IN A MODERATELY UNSTABLE ENVIRONMENT SHOULD PRODUCE PLENTY OF SHOWERS AND THUNDERSTORMS. NOT ANTICIPATING ANY WIDESPREAD STRONG TO SEVERE STORMS BUT GIVEN THE TIME OF YEAR CANNOT RULE OUT AN ISOLATED STRONGER STORM. ALTHOUGH THERE IS LIKELY TO BE A DIURNAL INCREASE IN ACTIVITY PRECIP CHANCES WILL REMAIN ELEVATED OVERNIGHT GIVEN FAVORABLE CONDITIONS. HIGH TEMPERATURES WILL CONTINUE TO RUN BELOW CLIMO WITH CLOUD COVER AND PRECIP KEEPING HIGHS IN THE LOW TO MID 80S. SOUTHERLY FLOW...INCREASING MOISTURE...AND CLOUD COVER WILL KEEP LOWS NEAR TO SLIGHTLY ABOVE CLIMO...LOW TO MID 70S. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 230 PM THURSDAY...ATYPICALLY WELL DEFINED (FOR THE TIME OF YEAR) MID AND UPPER LEVEL TROUGHINESS TO OUR WEST ON SUNDAY. DECAYING SURFACE BOUNDARY TO PROVIDE LOW LEVEL LIFT...WHICH WILL THEN BE AIDED BY MID LEVEL PVA AND UPPER DIVERGENCE ASSOC WITH RIGHT ENTRANCE OF UPPER JET STREAK ACROSS NORTHEAST AND MID ATLANTIC. AND WHILE RAIN CHANCES SEEM TO WARRANT LIKELY POPS MODELS ARE NOT SUGGESTIVE OF HIGH QPF AMOUNTS. THIS MAY BE DUE TO IT BEING SUCH A CLOUDY DAY THAT VERY LITTLE INSTABILITY MANAGES TO DEVELOP SAVE FOR PERHAPS ALONG THE IMMEDIATE COAST. THESE PLAYERS ALL REMAIN NEARLY IN PLACE HEADING INTO MONDAY ALTHOUGH ALL OF THEM WEAKEN. LOOKING FOR ANOTHER DAY OF HIGH POPS AND SUPPRESSED AFTERNOON TEMPS. TUESDAY SHOULD BRING LOWER RAIN CHANCES BUT STILL ONES THAT ARE HIGHER THAN NORMAL. THE UPPER JET CONTINUES TO WEAKEN AND LIFT OUT TO THE NORTHEAST WHILE THE MID LEVEL TROUGH WEAKENS...BUT ALSO SENDS ITS REMAINING VORT CENTER ACROSS THE CAROLINAS. IN RESPONSE TO THIS THE GFS STRAIGHTENS THE PIEDMONT TROUGH AT THE SURFACE. WE ALSO MAY SEE A BIT MORE SUNSHINE IN CONTRAST TO THE EARLY PARTS OF THE PERIOD. TUESDAY MAY THUS BE A DAY WHERE WE TRANSITION TO MORE SCATTERED AND DEEPER CONVECTION ESP IF TEMPS START BOUNCING BACK TOWARDS CLIMO. WEDNESDAY AND THURSDAY LOOK SEASONABLE WITH RESPECT TO BOTH TEMPERATURES AND AREAL COVERAGE OF CONVECTION. MID LEVEL FLOW SHOULD BE OF A DRIER WESTERLY DIRECTION WHILE SOME SEMBLANCE OF A PIEDMONT TROUGH REMAINS. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/...
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AS OF 00Z...SHOWERS WILL BE POSSIBLE THIS TAF VALID PERIOD AT ALL TERMINALS. THUNDERSTORM WILL ALSO BE POSSIBLE BUT SHOULD OCCUR NEAR THE COASTAL TERMINALS...OR IN THE AFTERNOON INLAND. TEMPO PERIODS OF MVFR CAN BE EXPECTED WITH BRIEF PERIODS OF IFR IN HEAVIER SHOWERS. WINDS WILL BE E-ESE AROUND 10KT HIGHEST AT THE COASTAL TERMINALS. RADAR AND SATELLITE TRENDS SUGGEST THAT KFLO/KLBT WILL BE MOST LIKELY TO EXPERIENCE SHRA/TEMPO MVFR THIS EVENING...ENDING AROUND MIDNIGHT. AFTERWARDS MVFR CONDITIONS WILL DEVELOP AND PERSIST THROUGH SUNRISE. SHRA/TEMPO MVFR WILL DEVELOP TOWARDS KMYR BY MIDNIGHT THEN SPREAD TO KCRE AND KILM OVERNIGHT. SHRA/VCTS WILL DEVELOP NEAR KFLO/KLBT IN THE LATE MORNING AND NEAR THE COASTAL TERMINALS IN THE AFTERNOON. EXTENDED OUTLOOK...SHRA/TSRA LIKELY WITH PERIODS OF MVFR CONDITIONS SAT THROUGH MON AS A FRONT STALLS AND FINALLY DISSIPATES OVER THE EASTERN CAROLINAS. CHANCE OF SHOWERS CONTINUES ON TUE.
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&& .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 730 PM THURSDAY...A WARM FRONT/COASTAL TROUGH WELL OFFSHORE WILL ACT IN CONCERT WITH A WEAK BUBBLE OF HIGH PRESSURE OFF THE MID-ATLANTIC COAST TO PRODUCE EASTERLY WINDS ACROSS THE COASTAL WATER TONIGHT. THE STRONGEST WINDS SHOULD OCCUR THIS EVENING WITH 15-20 KNOT WIND SPEEDS EXPECTED. A FEW GUSTS COULD REACH 23-24 KNOTS...BUT NOT QUITE ENOUGH FOR ANY ADVISORIES OR EXERCISE CAUTION HEADLINES. SEAS HAVE BUILT TO 4 FEET AT THE NEARSHORE WRIGHTSVILLE BEACH BUOY...AND I HAVE TWEAKED BOTH FORECAST WINDS AND SEAS HIGHER BASED ON LATEST OBSERVATIONS. CONDITIONS SHOULD BEGIN TO IMPROVE VERY LATE TONIGHT AS THE PRESSURE GRADIENT WEAKENS IN CLOSER PROXIMITY TO THE APPROACHING WARM FRONT. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 230 PM THURSDAY...PERIOD WILL BE DOMINATED BY SOUTHEAST FLOW AS FRONT STALLED OFFSHORE MOVES TO THE COAST FRI THEN PUSHES ONSHORE SAT. GRADIENT WILL BE WEAK FOR MUCH OF THE PERIOD WITH THE ONLY POSSIBLE EXCEPTION DURING FRI NIGHT WHEN GRADIENT SHARPENS AS BOUNDARY BECOMES A LITTLE MORE DEFINED. SPEEDS FRI NIGHT MAY TOUCH 15 KT BUT OTHERWISE SPEEDS WILL BE ON THE LOWER END OF THE 10 TO 15 KT RANGE. SEAS 2 TO 3 FT EARLY IN THE PERIOD INCREASE TO A SOLID 3 FT GIVEN THE PROLONGED SOUTHEAST WINDS AND DEVELOPMENT OF EAST-SOUTHEAST WIND WAVE. LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 230 PM THURSDAY...LIGHT SOUTHERLY WINDS ON SUNDAY WITH FRONTAL BOUNDARY JUST INLAND OF THE COAST. WIND CHOP WILL BE COINCIDENT WITH 11 SECOND SOUTHEASTERLY SWELL. THE WEAKENING BOUNDARY WILL MOVE FURTHER INLAND FOR THE REMAINDER OF THE PERIOD AND THE WEST ATLANTIC HIGH POKES A BIT WESTWARD FURTHER INTO THE CAROLINAS. THIS COULD LEAD TO AN OCCASIONAL INCREASE IN FLOW BY A FEW KNOTS AND ALSO A SLIGHT VEER FROM S TO SW.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...SGL SHORT TERM...III LONG TERM...MBB AVIATION...BJR

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