Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 231359 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1000 AM EDT WED JUL 23 2014 .SYNOPSIS... BERMUDA HIGH PRESSURE WILL BUILD INTO THE AREA TODAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST THURSDAY...STALLING NEAR THE COAST FOR THE WEEKEND. ANOTHER COLD FRONT WILL APPROACH FROM THE NORTHWEST MONDAY OR TUESDAY. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 1000 AM WEDNESDAY...INLAND FOG HAS BECOME A LOW STRATOCUMULUS DECK SINCE SUNRISE AND SHOULD LIFT FURTHER INTO A CUMULUS DECK OVER THE NEXT HOUR. THIS MOISTURE WILL BE THE SEED FOR SCATTERED THUNDERSTORMS THIS AFTERNOON WITH COVERAGE AVERAGING ABOUT 30 PERCENT OF THE FORECAST AREA. SYNOPTICALLY THE OLD STATIONARY FRONT NEAR THE COAST IS NEARLY GONE WITH BERMUDA HIGH PRESSURE OFFSHORE EXPECTED TO TURN SURFACE WINDS SOUTHWESTERLY LATER TODAY. A LANDBREEZE PUSHED OFFSHORE BEFORE SUNRISE WITH LIGHT WEST TO NORTHWEST WINDS OBSERVED AT THE BEACHES. THE DAYTIME SEABREEZE WILL TURN THESE WIND DIRECTIONS SOUTH TO SOUTHWESTERLY BY EARLY AFTERNOON. THE AIRMASS REMAINS QUITE MOIST WITH PRECIPITABLE WATER VALUES NEAR 2.0 INCHES AND SURFACE DEWPOINTS 72-75 DEGREES. LIGHT STEERING FLOW AND MODEST LAPSE RATES ALOFT WILL LIMIT THE COVERAGE AND DEVELOPMENT OF STORMS TODAY...BUT VIRTUALLY ALL MODEL GUIDANCE SHOWS THERE SHOULD BE SOME CONVECTIVE ACTIVITY OUT THERE THIS AFTERNOON. A LIMITING FACTOR THAT WILL STILL BE IN PLAY IS THE PRESENCE OF WIDESPREAD CONVECTION OVER THE GULF STREAM OFF THE GA-SC-NC COAST. SUSTAINED RISING MOTION WITHIN THIS CONVECTION WILL LEAD TO A CORRESPONDING RING OF SUBSIDENCE AROUND THE EDGE...INCLUDING OVER THE COASTAL CAROLINAS. FOR THIS REASON MY FORECAST POPS REMAIN BELOW THE GFS/NAM MOS CONSENSUS TODAY. I HAVE BUMPED FORECAST HIGHS UP A BIT WITH LOWER 90S FORECAST INLAND AND UPPER 80S AT THE COAST. WITH DEWPOINTS PROBABLY REMAINING IN THE LOWER 70S EVEN DURING PEAK HEATING WE COULD SEE HEAT INDICES REACH 100 DEGREES IN SPOTS THIS AFTERNOON.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 330 AM WEDNESDAY...SOME DRIER AIR STREAMING IN INITIALLY ON THURS WITH SOUTHWEST FLOW AND PCP WATER VALUES DOWN AROUND 1.5 INCHES BUT AS THE DAY PROGRESSES A COLD FRONT WILL MOVE INTO AND SLOWLY THROUGH THE CAROLINAS. AS THE FRONT APPROACHES FROM THE NORTHWEST THE GRADIENT WILL TIGHTEN WITH GUSTY SW WINDS AND INCREASING LOW LEVEL WINDS UP TO 30 KTS. MOISTURE POOLS AHEAD OF THE FRONT WITH INCREASED CONVECTIVE ACTIVITY BY LATE THURS AS PCP WATER VALUES REACH UP OVER 2 INCHES. EXPECT MOST WIDESPREAD SHWR/TSTM ACTIVITY BY LATE THURS AFTN AS PRE FRONTAL TROUGH NEARS THE AREA AND GREATEST SHORTWAVE ENERGY RIDES AROUND THE BASE OF THE H5 TROUGH THROUGH THE CAROLINAS. THE BEST UPPER LEVEL SUPPORT WILL LAY JUST WEST OF LOCAL FORECAST AREA ON THURS AFTN BUT HEADING INTO THURS NIGHT...STEERING FLOW WILL VEER TO BECOME MORE SW TO W AND SHOULD SEE A FAIR AMOUNT OF CONVECTION INTO OUR AREA. THE FRONT WILL GET HUNG UP OVER THE COASTAL CAROLINAS AND SHOULD SEE FRIDAY MORE ACTIVE ALONG THE COAST WHILE DRIER AIR WILL MAKE ITS WAY IN ACROSS INLAND AREAS. THE MID TO UPPER TROUGH SHIFTS OFF THE COAST THROUGH FRI NIGHT BEFORE IT LIFTS OFF TO THE NORTHEAST LEAVING A DEEPER DRIER FLOW AND INCREASED SUBSIDENCE HEADING INTO EARLY SATURDAY. DECENT WESTERLY DOWNSLOPE COMPONENT TO THE WINDS WITH LOW LEVEL THICKNESSES PEAKING THURS. EXPECT HIGH TEMPS TO REACH INTO THE 90S AND WITH DEWPOINT TEMPS INTO THE 70S...TEMPS WILL FEEL AS IF THEY ARE OVER 100 DEGREES IN PLACES ESPECIALLY ACROSS NORTHEAST SOUTH CAROLINA. AS TROUGH DIGS DOWN AND HEIGHTS LOWER FOR FRIDAY...EXPECT TEMPS TO BE A FEW DEGREES LOWER BUT STILL UP AROUND 90. CLOUDS AND INCREASED SHWR ACTIVITY WILL AFFECT THE TEMPS ESPECIALLY LATE THURS THROUGH EARLY FRI. LOW TEMPS BOTH NIGHTS WILL BE IN THE MID 70S. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 330 AM WEDNESDAY...LINGERING COLD FRONT MAY REMAIN NEAR THE COAST AS IT WEAKENS LEAVING WEAK HIGH PRESSURE OVER THE AREA FOR THE WEEKEND. ALTHOUGH THE SURFACE BOUNDARY REMAINS CLOSE BY...ENOUGH DRY AIR WILL MAKE ITS WAY INTO THE AREA IN WESTERLY FLOW ALOFT WITH COLUMN MOISTURE APPRECIABLY LOWER ABOVE H85. PCP WATER VALUES WILL BE DOWN NEAR 1.5 INCHES THROUGH SATURDAY AND EVEN LOWER INLAND. THE GRADIENT WILL RELAX AS THE FRONT SHIFTS SOUTH AND EAST AND WEAKENS THROUGH SATURDAY. MID TO UPPER TROUGH LIFTS FAR ENOUGH OUT OF AREA AND ALTHOUGH A BROAD TROUGH REMAINS OVER THE GREAT LAKES...HEIGHTS WILL RISE OVER THE CAROLINAS AS RIDGE TRIES TO NOSE INTO THE SOUTHEAST THROUGH THE WEEKEND. OVERALL EXPECT A GOOD DEAL OF SUNSHINE THROUGH THE WEEKEND WITH LOWER POPS IN MORE LOCALIZED SHWR ACTIVITY AND WARM TEMPS. BY LATE SUNDAY INTO MONDAY THE MID TO UPPER TROUGH BEGINS TO DIG SOUTH AGAIN PUSHING ANOTHER COLD FRONT EAST INTO THE CAROLINAS. THEREFORE SHOULD SEE ANOTHER ROUND OF INCREASED CONVECTIVE ACTIVITY ACROSS THE AREA AHEAD AND ALONG THE COLD FRONT AS IT MOVES THROUGH THE COASTAL CAROLINAS MONDAY INTO EARLY TUES. LOOKS LIKE THE MAIN H5 TROUGH AXIS WILL SHIFT OFF THE COAST TUES PUSHING FRONT FAR ENOUGH EAST TO ALLOW FOR DEEPER DRIER AIR TO MOVE INTO THE AREA AS HIGH PRESSURE BUILDS IN FOR MID WEEK. THE MAIN TROUGH WILL CONTINUE TO PLAGUE THE EAST COAST WITH LOWER HEIGHTS AND TEMPS PUSHED TO THE COOLER SIDE OF CLIMO FOR MID WEEK NEXT WEEK. TEMPS WILL START OUT ABOVE NORMAL IN A WARM AND HUMID AIR MASS WITH READINGS IN THE 90S FOR HIGHS THROUGH MUCH OF THE WEEKEND BUT BY TUES MAX TEMPS WILL BE IN THE 80S MOST PLACES WITH DEWPOINT TEMPS DROPPING INTO THE 60S. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... AS OF 12Z...AREAS OF IFR THIS MORNING DUE TO LOW CIGS AND AREAS OF FOG...IMPROVING TO VFR LATER THIS MORNING AND CONTINUING THROUGH TONIGHT WITH ISOLATED TO SCATTERED SHRA/TSRA POSSIBLE TODAY. OVERNIGHT POSSIBLE MVFR/IFR DUE TO PATCHY FOG. WHILE THE COASTAL SITES ARE CURRENTLY VFR...IFR PREVAILS AT THE INLAND SITES DUE TO FOG AND LOW CIGS...WHICH WILL IMPROVE TO VFR OVER THE NEXT FEW HOURS. LATEST RADAR IMAGERY DEPICTS ALL SHRA/TSRA ACTIVITY OFFSHORE THIS MORNING...BUT EXPECT THROUGHOUT THE DAY FOR CHANCES TO INCREASE FOR ISOLATED TO SCATTERED SHRA/TSRA ACROSS THE AREA...TAPERING OFF LATER THIS EVENING. AS FOR WINDS...SOUTHWESTERLY WINDS ARE EXPECTED WITH SUSTAINED WINDS AOB 10 KTS. OVERNIGHT INTO THURSDAY MORNING...EXPECT VFR TO PREVAIL WITH THE EXCEPTION OF THE INLAND SITES WHICH MAY EXPERIENCE MVFR/IFR DUE TO FOG BEFORE DAYBREAK. EXTENDED OUTLOOK...CHANCE OF SHOWERS/TSTMS WILL PERSIST THROUGH THE EXTENDED PERIOD. EXPECT PREDOMINANTLY VFR CONDITIONS WITH TEMPO PERIODS OF MVFR/IFR CIGS/VSBYS IN STORMS. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM WEDNESDAY...MORE TYPICAL MID-SUMMER WEATHER WILL DEVELOP TODAY AS THE OLD STATIONARY FRONT OF THE PAST TWO DAYS DISSIPATES AND BERMUDA HIGH PRESSURE WELL OFFSHORE TAKES HOLD. A WEAK LANDBREEZE PUSHED OFFSHORE BEFORE SUNRISE PRODUCING WEST TO NORTHWEST WINDS ACROSS THE COASTAL WATERS. THESE WIND DIRECTIONS SHOULD TURN BACK ONSHORE THIS AFTERNOON WITH THE SEABREEZE...WITH WIND SPEEDS INCREASING TO NEAR 15 KNOTS BY EARLY EVENING. THE OVERALL PRESSURE GRADIENT SHOULD TIGHTEN OVERNIGHT WITH 12-16 KNOT WINDS EXPECTED THROUGH MUCH OF THE NIGHT. SEAS CURRENTLY CONSIST ALMOST EXCLUSIVELY OF A 7-8 SECOND SOUTHEAST SWELL AROUND 3 FT...PERHAPS CLOSER TO 2 FEET ALONG THE SOUTH CAROLINA COAST WHERE WE HAVE NO BUOY DATA. A LITTLE MORE WIND CHOP SHOULD DEVELOP ON TOP BY THIS EVENING...WITH COMBINED SEAS AVERAGING 3-4 FEET AWAY FROM SHORE. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 330 AM WEDNESDAY...COLD FRONT WILL MOVE SLOWLY THROUGH THE CAROLINAS LATE THURS INTO FRIDAY BEFORE STALLING OUT NEAR THE COAST ON FRI. OVERALL SHOULD SEE A TIGHTENED GRADIENT FLOW OUT OF THE SOUTHWEST UP TO 15 TO 20 KTS LATE THURS INTO EARLY FRI. SEAS AROUND 2 TO 4 FT EARLY THURS WILL BUILD UP TO 3 TO 5 FT BY THURS EVE AND POSSIBLY REACHING CLOSE TO SCA THRESHOLDS THURS EVE. WINDS AND SEAS WILL DIMINISH THROUGH FRIDAY AS FRONT WEAKENS ALONG THE CAROLINA COAST. MAY SEE A PERIOD OF MORE W WINDS ON FRI DEPENDING ON HOW CLOSE THE FRONT MAKES IT BEFORE COMING BACK AROUND TO THE S-SW THROUGH THE WEEKEND. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 330 AM WEDNESDAY...WILL MAINTAIN A SW FLOW AROUND BERMUDA HIGH AROUND 10 TO 15 KTS THROUGH SATURDAY. THE WINDS WILL INCREASE SAT NIGHT THROUGH SUNDAY AS GRADIENT TIGHTENS AS PIEDMONT TROUGH BECOMES MORE PRONOUNCED AND NEXT COLD FRONT APPROACHES THE WESTERN CAROLINAS BY EARLY MONDAY. SEAS WILL DIMINISH THROUGH SAT MORNING AND THEN WILL BEGIN A RISE THROUGH SAT NIGHT AND SUNDAY POSSIBLY REACHING ABOVE SCA THRESHOLDS BY SUN NIGHT. SEAS 3 FT OR LESS SAT MORNING WILL REACH UP TO 3 TO 5 FT BY SUN EVENING AND NEAR 6 FT BY EARLY MON MORNING.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RGZ AVIATION...SGL

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