Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 101542 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1142 AM EDT THU JUL 10 2014 .SYNOPSIS... A COLD FRONT WILL STALL ACROSS THE REGION TONIGHT...PERSISTING INTO EARLY SATURDAY. THIS WILL BRING GOOD CHANCES FOR THUNDERSTORMS THE NEXT FEW DAYS...WITH PERIODS OF HEAVY RAINFALL. THIS FRONT WILL DISSIPATE LATE IN THE WEEKEND WITH A RETURN TO TYPICAL SUMMERTIME CONDITIONS...WITH A WARMING TREND DEVELOPING EARLY NEXT WEEK. ANOTHER COLD FRONT WILL APPROACH ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1100 AM THURSDAY...SHWRS/TSTMS AND CLOUDS OVER CAPE FEAR THIS MORNING HAVE LOWERED TEMPS INTO MID 70S...LOWER THAN THEY HAVE BEEN FOR PAST FEW DAYS. SHOULD SEE THIS CONVECTION WEAKEN THROUGH THE MORNING BEFORE OTHER STORMS DEVELOP ALONG SEA BREEZE BOUNDARY AND OTHER OUTFLOW BOUNDARIES JUST INLAND OF THE COAST EARLY THIS AFTERNOON AND TRANSLATING INLAND THROUGH LATER THIS AFTERNOON. OVERALL EXPECT GREATER COVERAGE OF STORMS THROUGH TONIGHT AS COLD FRONT SLOWS DOWN AS IT APPROACHES FROM THE NORTHWEST THROUGH TONIGHT. VERY MOISTURE RICH AIR LIES AHEAD OF THE FRONT WITH PCP WATER VALUES UP CLOSE TO 2 INCHES. CONVERGENCE ALONG LOCALIZED BOUNDARIES WILL REMAIN THE FOCAL POINT FOR CONVECTION OVER MOST OF AREA WITH BEST COVERAGE JUST AHEAD OF FRONT. UPPER LEVEL SUPPORT WILL INCREASE THROUGH THE DAY AS TROUGH SHIFTS EAST. LOOKS LIKE BEST JET DYNAMICS WILL BE LOCATED TO THE NORTHWEST OF FORECAST AREA. WITH A STORM MOTION OUT OF THE SOUTHWEST AT 10 MPH...SOME TRAINING OF CELLS COULD PRODUCE POTENTIAL FOR FLOODING THROUGH THIS AFTERNOON. ALTHOUGH CELL MOTION WILL BE FROM SOUTHWEST TO NORTHEAST...THE STORMS WILL SHIFT EASTWARD THROUGH TIME AS UPPER LEVEL TROUGH PUSHES FRONT SLOWLY EAST. LAPSE RATES REMAIN FAIRLY NEUTRAL WITH LESS OVERALL HEATING IN MOST PLACES LIMITING THE CONVECTION POTENTIAL BUT CLOUD FREE SPOTS WILL HEAT UP PRODUCING AREAS OF DIFFERENTIAL HEATING ADDING TO STORM DEVELOPMENT. SPC MENTIONS COASTAL PLAIN AS FOCAL POINT WITH RISK OF DAMAGING WIND GUSTS. CLOUDS AND PCP WILL KEEP TEMPS FROM REACHING AS HIGH AS PAST COUPLE OF DAYS WITH HIGHS OF 85 TO 90 MOST PLACES. AREAS THAT COOLED DOWN FROM RAIN THIS MORNING WILL BE SLOWER TO RISE REACHING THE MID 80S BY THIS AFTERNOON. THE CLOUDS AND SHWRS WILL KEEP OVERNIGHT LOWS HIGHER ONCE AGAIN...REMAINING IN THE MID TO UPPER 70S MOST PLACES. THE COLD FRONT WILL HANG OVER THE AREA TONIGHT WITH POTENTIAL FOR CONVECTION INTO FRIDAY. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 330 AM THURSDAY...FRIDAY CONTINUES TO LOOK VERY WET LOCALLY AS ELEMENTS COMBINE TO PRODUCE WIDESPREAD CONVECTION WITH HEAVY RAIN. AT THE SURFACE...A WEAKENING COLD FRONT WILL BE WAVERING ACROSS THE CWA...AND THIS...ALONG WITH REMNANT OUTFLOW BOUNDARIES FROM CONVECTION ON THURSDAY...WILL SERVE AS FOCI FOR UPDRAFTS ON FRIDAY. ALOFT...SHEAR LINE DEMARCATING THE LONGWAVE TROUGH AXIS WILL SWING OVERHEAD AND NORTHEAST DURING THE DAY...WHILE 300MB 100KT JET MOVES OVER NEW ENGLAND...LEAVING THE CAROLINAS WITHIN THE FAVORABLE RFQ DIFLUENT REGION...IN A SETUP THAT RESEMBLES QUITE WELL A MADDOX-TYPE EVENT FROM LITERATURE FOR HEAVY RAIN. ALL THIS OCCURS IN A THERMODYNAMIC ENVIRONMENT CHARACTERIZED BY SBCAPE OF 800-1000 J/KG...PWATS OVER 2 INCHES...AND WARM CLOUD DEPTH APPROACHING 11 KFT. THE "LONG SKINNY" CAPE PROFILE SUGGESTS EFFICIENT PRECIPITATION PROCESSES (LONGER PARCEL RESIDENCE TIMES WITHIN STRONG COLLISION-COALESCENCE ENVIRONMENT) IN UPDRAFTS FRIDAY AS WELL...SO ALL SIGNS POINT TO A VERY ACTIVE DAY WITH HEAVY RAINFALL THE PRIMARY THREAT WITHIN THUNDERSTORMS. ALTHOUGH DRIER AIR WILL SLOWLY BEGIN TO FILTER INTO THE MID-LEVELS AS AN EMBEDDED SHORTWAVE PUSHES OFFSHORE LATE FRIDAY...STILL ANTICIPATE A SIGNIFICANT QPF DAY...HIGHEST EASTERN HALF OF THE CWA. TEMPS WILL BE TEMPERED BY THE WIDESPREAD CLOUDS AND RAIN...RISING ONLY INTO THE MID/UPR 80S. LOWS AT NIGHT WILL DROP INTO THE MID 70S AT THE COAST...BUT AROUND 70 WELL INLAND WHERE DRIER AIR WILL BECOME MORE PRONOUNCED LATE. SATURDAY WILL BE A TRANSITIONAL DAY AS RIDGING FROM THE SOUTHWEST TRIES TO BLOSSOM ACROSS THE AREA. IT WILL GET SHUNTED EAST BY THE AFOREMENTIONED LONGWAVE TROUGH...BUT THE WESTERLY FLOW BETWEEN THESE TWO FEATURES WILL HELP TO DRY THE COLUMN FROM FRIDAY. AT THE SAME TIME...THE SUBTLE THICKNESS INCREASE WILL HELP TO FURTHER ERODE THE FRONT WHICH SHOULD BECOME INDISTINGUISHABLE ON SATURDAY. HOWEVER...IT WILL CONTINUE TO HELP DRIVE CONVECTION...ALBEIT IN A LESS SIGNIFICANT MANNER THAN FRIDAY. STILL ANTICIPATE SCATTERED TSTMS SATURDAY AREA-WIDE...WITH TEMPS AGAIN JUST BELOW NORMAL IN THE UPR 80S TO AROUND 90...AND LOWS A FEW DEGREES ABOVE 70. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 330 AM THURSDAY...SEASONABLE CONDITIONS TO BEGIN THE PERIOD AS RIDGING DEVELOPS ALOFT AND HIGH PRESSURE OFFSHORE RIDGES BACK TOWARDS THE COAST. MID-LEVEL WESTERLY FLOW WILL CAUSE A RELATIVELY DRY COLUMN ON SUNDAY...SO ONLY ISOLATED CONVECTION IS ANTICIPATED...LIKELY LESS THAN CLIMATOLOGICALLY NORMAL. WITH HEIGHTS BUILDING ALOFT AND RETURN FLOW DEVELOPING...TEMPS SUNDAY WILL WARM TO SEASONABLE VALUES. THEREAFTER...HEAT WILL SLOWLY BUILD AGAIN THROUGH TUESDAY THANKS TO SUBTLE THICKNESS INCREASE DOWNSTREAM OF A LARGE TROUGH ACROSS THE MIDWEST...AND CONTINUED RETURN FLOW AT THE SURFACE. THIS DRIVES MORE TYPICAL CONVECTION CHANCES MONDAY/TUESDAY...BEFORE A COLD FRONT APPROACHES AND STALLS ACROSS THE AREA BY WEDNESDAY. THIS WILL BRING MUCH MORE WIDESPREAD PRECIP CHANCES FOR THE MIDDLE OF NEXT WEEK...ALONG WITH TEMPERATURES COOLING BACK TO SEASONABLE LEVELS. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 12Z...SHOWERS AND ISOLATED THUNDERSTORMS ARE OCCURRING NEAR THE COASTAL TERMINALS WITH GENERALLY MVFR CIGS AND S-SW WINDS 5-10KT. AT KFLO/KLBT CIGS ARE VFR WITH MVFR VSBYS IN BR AND LIGHT SE-S WINDS. EXPECT LITTLE CHANGE THROUGH MID MORNING EXCEPT VSBYS SHOULD INCREASE AT KFLO/KLBT AS BR BURNS OFF. BY LATE MORNING WINDS WILL INCREASE FROM THE S AT THE COASTAL TERMINALS. SHRA/TSRA SHOULD BECOME MORE LIKELY AT KFLO/KLBT AND LESS LIKELY AT THE COASTAL TERMINALS. DURING THE AFTERNOON THE BULK OF THE CONVECTION WILL AFFECT KFLO/KLBT...MOVING TO THE COASTAL TERMINALS IN THE EVENING. DUE TO UNCERTAINTIES IN TIMING AND COVERAGE WILL INDICATE MVFR CONDITIONS WITH CONVECTION. SHORT TERM IFR IS ALMOST CERTAIN TO OCCUR BUT SHOULD NOT LAST 15-30 MINUTES AT ANY ONE TERMINAL... UNLESS A TERMINAL HAPPENS TO BE UNDER TRAINING CELLS. CONVECTION BECOMES ISOLATED 06-12Z...MOST LIKELY AT KLBT AND NEAR THE COASTAL TERMINALS. MVFR VSBYS IN BR ARE ALMOST CERTAIN TO OCCUR 06-12Z AT KFLO/KLBT. CONFIDENCE OF IFR IS LOW DUE TO CLOUD COVER. EXTENDED OUTLOOK...A FRONT STALLS OVER THE REGION WITH A DECENT CHANCE FOR SHRA/TSRA THROUGH SATURDAY...MAINLY IN THE AFTERNOON. SHRA/TSRA ARE AGAIN POSSIBLE MONDAY. BRIEF IFR CONDITIONS ARE POSSIBLE IN THE HEAVIER SHOWERS AND STORMS. OTHERWISE VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1100 AM THURSDAY...SOUTHWESTERLY FLOW WILL CONTINUE OVER THE WATERS THROUGH TONIGHT AS HIGH PRESSURE OVER THE WESTERN ATLANTIC INTERACTS WITH AN APPROACHING COLD FRONT WELL INLAND. SEAS WILL REMAIN 2 TO 4 FT MOST WATERS. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 330 AM THURSDAY...A WEAKENING COLD FRONT WILL WAVER IN THE VICINITY THROUGH SATURDAY...LIKELY REMAINING JUST WEST OF THE COASTAL WATERS DURING THIS PERIOD. THAT LEAVES A WEAK GRADIENT...AND S/SE WINDS FRIDAY AND SATURDAY AT 10 KTS OR LESS. LATE SATURDAY THE COLD FRONT WILL WASH OUT...AND AS HIGH PRESSURE BECOMES DOMINANT OFFSHORE...WINDS WILL VEER TO BECOME MORE SWLY...REMAINING AROUND 10 KTS. WAVE HEIGHTS WILL BE HIGHEST ON FRIDAY...THANKS TO WINDS EASING FROM THURSDAY...WITH 3-4 FT SEAS LIKELY ON A SOUTHERLY WIND CHOP. THESE HEIGHTS WILL DROP TO 1-3 FT ON SATURDAY ON THE LIGHTER WINDS. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 330 AM THURSDAY...MORE TYPICAL SUMMERTIME PATTERN WILL DEVELOP LATE IN THE WKND AND EARLY NEXT WEEK AS HIGH PRESSURE OFFSHORE EXERTS ITS INFLUENCE ACROSS THE COASTAL WATERS. SW WINDS WILL SLOWLY INCREASE THROUGH THE PERIOD...BECOMING 15-20 KTS LATE MONDAY. THE COMBINATION OF THESE RISING WINDS AND AN AMPLIFYING GROUND SWELL WILL DRIVE SEAS UP FROM 2-3 FT SUNDAY...TO 3-5 FT MONDAY...AND CAUTIONARY STATEMENTS MAY BE NEEDED EARLY NEXT WEEK. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...RGZ SHORT TERM...JDW LONG TERM...JDW AVIATION...MRR

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