Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 042250 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 650 PM EDT FRI SEP 4 2015 .SYNOPSIS... A COOLER AND SOMEWHAT WETTER PATTERN WILL DEVELOP THIS WEEKEND AS HIGH PRESSURE BUILDS IN FROM THE NORTHEAST. THIS PATTERN WILL WEAKEN EARLY NEXT WEEK AS A MORE TYPICAL LATE SUMMER BENIGN PATTERN DEVELOPS. A COLD FRONT WILL APPROACH THE REGION LATE NEXT WEEK AS WELL. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 650 PM FRIDAY...WATER VAPOR ANIMATIONS REVEAL SEVERAL PERTURBATIONS ALOFT AND CYCLONIC TURNING OF THE ATMOSPHERE ACROSS THE FORECAST AREA. DRY AIR NOSING INTO THE REGION FROM THE NW WAS AIDING IN WEAK UPPER VERTICAL CIRCULATIONS...WHILE A HOST OF OUTFLOW BOUNDARIES SNAKED ACROSS THE CAROLINAS...ACCOMPANIED BY AN INLAND MOVING BUT WEAKENING SEA BREEZE FRONT. DIURNAL COOLING WILL LIKELY KILL SOME DISCREET CELLS ABOUT THE AREA...BUT THE CONVECTION ALONG AND NEAR THE SURFACE BOUNDARY DROPPING SOUTHWARD INTO SE NC MAY HOLD TOGETHER DUE TO ENHANCED SURFACE CONVERGENCE AND WEAK SUPPORT ALOFT. AS A RESULT WILL INCREASE POP VALUES MAINLY THIS EVENING FROM NORTH TO SOUTH OVER SE NC TONIGHT AS THE FOCUS DROPS SOUTH IN THE WEAK STEERING FLOW. THE PREVIOUS FORECAST DISCUSSION FOR THE OVERNIGHT PERIOD FOLLOWS. WILL KEEP POPS INTO TONIGHT BUT EXPECT DRIER AIR TO SURGE IN FROM THE NORTHEAST BEHIND COLD FRONT INTO THE EARLY MORNING HOURS. GFS SHOWS BOUNDARY PUSHING THROUGH AREA FROM N-NE TO S-SW WITH PCP WATER VALUES UP CLOSER TO 1.8 INCHES AHEAD OF IT AND DROPPING TO AS LOW AS 1.2 INCHES BEHIND IT...REACHING INTO SOUTHEAST NORTH CAROLINA BY DAY BREAK AND CONTINUING TOWARD THE SW THROUGH TOMORROW MORNING. BUT MAY SEE SOME LOW CLOUDS AROUND WITH SHALLOW MOISTURE EVIDENT ON MOISTURE PROFILES. ALTHOUGH MORE MOISTURE WILL REACH IN BEHIND IT...EXPECT DRYING INTO THE MORNING FROM THE NE. TEMPS WILL DROP AFTER MIDNIGHT WITH LOWEST READINGS NEAR OR JUST BELOW 70 TO THE NORTHEAST AND WARMEST WITH LOWER 70S TO THE SOUTH TO SOUTHWEST. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 330 PM FRIDAY...THE REX BLOCK CONFIGURATION WILL PREVAIL THROUGH MOST OF THE PERIOD AT THE MID LEVELS ABATING SLIGHTLY LATE SUNDAY WHEN THE RIDGE WEAKENS TO THE NORTH. AT THE SURFACE ITS A BIT SIMPLER WITH HIGH PRESSURE EXTENDING DOWN FROM THE NORTHEAST IN A WEDGE CONFIGURATION. FORCING FOR POPS APPEARS TO BE IN THE FORM OF CONVECTIVE PROCESSES PER THE GFS. ISENTROPIC LIFT IS NOTABLY ABSENT FROM LIFT PER DEEPER NORTHEAST FLOW. ANYHOW...WITH RELATIVELY DRY PROFILES SATURDAY...AND VERY WEAK CONVERGENCE AT THE SURFACE...POPS ARE MINIMAL. BOTH ELEMENTS INCREASE SUNDAY AS BASICALLY THE SEABREEZE IS SHOWN DUE TO A WEAKER NORTHEAST FLOW AND MODELS RESPOND WITH GOOD CONVECTION ALONG THIS BOUNDARY AND SOME DECENT COVERAGE ELSEWHERE. TEMPERATURE FORECAST REMAINS ESSENTIALLY UNCHANGED FROM THE PREVIOUS PACKAGE. SLIGHTLY COOLER FOR SUNDAY VIA MORE EXPECTED CONVECTION. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 330 PM FRIDAY...MODELS SHOW THE MAIN JET RIDING WELL N OF THE EASTERN CAROLINAS THROUGH WED. FURTHER SOUTH...A WEAK 500 MB TROUGH OF LOW PRESSURE WILL DRIFT WEST AS HIGH PRESSURE RETROGRADES. THU AND FRI...A LONGWAVE TROUGH BEGINS TO DIG ACROSS THE GREAT LAKES AND THROUGH THE MISSISSIPPI VALLEY AND MID SOUTH. A SERIES OF RATHER ROBUST MID-LEVEL SHORTWAVES HELP TO CARVE OUT THIS TROUGH. SOME OF THIS SHORTWAVE ENERGY SHOULD GET CLOSE ENOUGH LATE NEXT WEEK TO WARRANT HIGHER POPS. AT THE SURFACE...HIGH PRESSURE WILL WEDGE SOUTH EARLY IN THE WEEK THEN WEAKEN. A SURFACE TROUGH WILL DEVELOP UPSTREAM WED-FRI AND THIS ALONG WITH THE SEABREEZE BOUNDARY WILL PROVIDE ADDED LIFT FOR AT LEAST WIDELY SCATTERED TO SCATTERED THUNDERSTORMS GIVEN PRECIPITABLE WATER VALUES FOR MOST OF THE PERIOD WILL RANGE FROM 1.75 INCHES TO NEAR 2 INCHES. HIGH TEMPS WILL BEGIN TO INCREASE AFTER MONDAY...RISING ABOVE NORMAL MID AND LATE WEEK. LOW TEMPS WILL BE NEAR NORMAL. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 18Z...VFR EXPECTED THIS AFTERNOON AND EVENING. WINDS WILL BE LIGHT AND VARIABLE OR LIGHT N-NE...EXCEPT BECOMING E-SE AT THE COASTAL TERMINALS. AS WINDS BECOME SE AT THE COASTAL TERMINALS ISOLATED SHOWERS WILL DEVELOP ALONG A RESULTANT BOUNDARY JUST INLAND OF THE COAST. AS THE BOUNDARY SHIFTS FURTHER INLAND AS THE AFTERNOON PROGRESSES THERE SHOULD BE LESS CHANCE OF SHOWERS AT THE COASTAL TERMINALS. DURING THE EVENING AN APPROACHING COLD FRONT WILL INCREASE THE POTENTIAL FOR SHOWERS AT KLBT/KILM...WITH BEST CONFIDENCE FOR ANY TS AT KLBT. SHOWERS WILL DECREASE BUT REMAIN POSSIBLE THE REMAINDER OF THE EVENING AND OVERNIGHT AS THE FRONT MOVES SOUTH THROUGH THE REMAINING TERMINALS. WINDS SPEEDS SUGGEST VSBYS WILL REMAIN MOSTLY VFR BUT CAN`T DISCOUNT SOME TEMPO MVFR VSBYS UNTIL THE FRONT PASSES. TIME HEIGHT ANALYSIS SUGGESTS THE POSSIBILITY OF IFR/MVFR CIGS IN THE PRE- DAWN HOURS UNTIL MID MORNING. EXTENDED OUTLOOK...PREDOMINATELY VFR WITH BRIEF MVFR AND POSSIBLY IFR...IN MORNING FOG...AND ISOLATED/SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS SPECIFICALLY SUNDAY THRU TUESDAY TIME FRAME. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 650 PM FRIDAY...PRESSURE PATTERN OVER THE WATERS REMAINS WEAK AND SHOULD REMAIN THIS WAY INTO THE EVENING WITH SEA BREEZE DOMINATING THE FLOW...ESPECIALLY THROUGH THIS AFTN. THEREFORE EXPECT ON SHORE GUSTIER WINDS THIS AFTERNOON....BASICALLY REMAINING 10 KTS. THE GRADIENT WILL BEGIN TO STRENGTHEN WITH THE APPROACH OF A COLD FRONT LATER THIS EVENING INTO THE OVERNIGHT HOURS. EXPECT A NORTHERLY SURGE UP TO 15 KTS OR SO. SEAS RUNNING LESS THAN 2 FT WILL INCREASE UP CLOSER TO 3 FT IN LIGHT NORTHERLY SURGE AFTER MIDNIGHT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 330 PM FRIDAY...NORTHEAST WINDS WILL BE THE STORY ACROSS THE COASTAL WATERS THROUGHOUT THE WEEKEND AS HIGH PRESSURE REMAINS FIRMLY IN PLACE ACROSS WHERE ELSE...THE NORTHEAST. LITTLE IN THE WAY TO CHANGE WIND SPEEDS FROM A RANGE OF 10 TO 15 KNOTS AS WELL. THERE MAY BE A BRIEF UPTICK SUNDAY AFTERNOON AS THE SEA BREEZE KICKS IN. SIGNIFICANT SEAS SHOULD BE IN A 2 TO 4 FOOT RANGE. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 330 PM FRIDAY...WEDGE OF HIGH PRESSURE WILL CONTINUE MONDAY WITH TROUGH STREWN OFFSHORE. THIS WILL KEEP NE WINDS ACROSS THE WATERS WITH A TIGHTER PRESSURE GRADIENT ACROSS THE NEAR SHORE WATERS THAN FURTHER OFFSHORE. THIS GRADIENT WILL RELAX MON NIGHT AS THE WEDGE WEAKENS AND THE WINDS WILL BEGIN TO TURN TO A MORE SOUTHERLY DIRECTION...BECOMING LIGHT AND VARIABLE WITH AN OFFSHORE BIAS TUE MORNING AS THE LAND BREEZE MOVES OUT ACROSS THE WATERS. SSW WINDS WILL RETURN TUE AFTERNOON AND SEABREEZE INFLUENCES SHOULD ALLOW FOR STRONGER WINDS AS THE AFTERNOON PROGRESSES. A SIMILAR SCENARIO IS EXPECTED ON WED...BUT BY THAT TIME THE WINDS WILL BE A LITTLE STRONGER ACROSS THE WATERS AS A TROUGH SHARPENS INLAND. THE HIGHEST WINDS SPEEDS THIS PERIOD WILL BE AROUND 15 KT LATER TUE AFTERNOON AND ESPECIALLY WED AFTERNOON. SEAS WILL BE 2 TO 3 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...MJC SHORT TERM...SHK LONG TERM...RJD AVIATION...MRR

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