Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 131057 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 656 AM EDT SUN JUL 13 2014 .SYNOPSIS... HIGH PRESSURE RIDGING WEST ACROSS THE AREA WILL BRING A SEASONABLE AND MOSTLY DRY DAY TODAY...BEFORE HOT AND HUMID CONDITIONS DEVELOP MONDAY AND TUESDAY. HEAT INDICES EARLY IN THE WEEK WILL EXCEED 100 DEGREES. A COLD FRONT WILL APPROACH LATE TUESDAY...AND THEN STALL ACROSS THE AREA THROUGH THE UPCOMING WEEK. THIS WILL BRING COOLER THAN NORMAL TEMPERATURES AND GOOD CHANCES FOR SHOWERS AND THUNDERSTORMS EACH DAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 2 AM SUNDAY...LIGHT WINDS WILL BECOME CALM OVERNIGHT ALLOWING SOME RADIATIONAL COOLING...ESPECIALLY INLAND. THIS WILL ALLOW TEMPS TO DROP INTO THE UPPER 60S IN PLACES AS WELL AS INCREASE POTENTIAL FOR FOG. BOUNDARY LAYER WINDS ARE FORECAST TO BE A LITTLE HIGHER THAN LAST NIGHT AND DO NOT EXPECT WIDESPREAD VISIBILITIES BELOW 1SM. ABUNDANT MID LEVEL DRY AIR AND SUBSIDENCE IN PLACE TODAY WILL KEEP SKIES MOSTLY SUNNY AND SEVERELY LIMIT PRECIP CHANCES. PRECIPITABLE WATER VALUES HANG AROUND 1.2 INCHES...WELL BELOW THE 1.75 INCHES TYPICAL FOR MID JULY AND MID LEVEL LAPSE RATES ARE IN THE 5 TO 5.5 C/KM RANGE. CANNOT RULE OUT ISOLATED WEAK SHOWERS ALONG OR JUST BEHIND THE SEA BREEZE...SIMILAR TO YESTERDAY...BUT MOST AREAS WILL REMAIN DRY. ANY SHOWERS THAT DO DEVELOP WILL BE HARD PRESSED TO LAST FOR AN EXTENDED PERIOD OF TIME GIVEN THE HARSH MID LEVEL ENVIRONMENT. HIGHS TODAY WILL AGAIN CLIMB INTO THE LOWER 90S AWAY FROM THE COAST. SEA BREEZE SHOULD MAKE GOOD PROGRESS INLAND GIVEN THE SOUTH TO SOUTHEAST SYNOPTIC FLOW. ALONG THE COAST EARLY SEA BREEZE DEVELOPMENT WILL KEEP HIGHS IN THE MID TO UPPER 80S. LIGHT SOUTHERLY FLOW OVERNIGHT WILL KEEP LOWS NEAR TO SLIGHTLY ABOVE CLIMO. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 330 AM SUNDAY...HOT AND HUMID WITH INCREASINGLY UNSETTLED WEATHER WILL DEFINE THE SHORT TERM. VERY UNCOMFORTABLE WEATHER EXPECTED BOTH DAYS FOR THE EARLY WORK-WEEK PERIOD...AS RETURN FLOW PUMPS WARM MOIST AIR INTO THE CAROLINAS...AND THE MUCH-DISCUSSED APPROACHING COLD FRONT GETS HUNG UP WEST OF THE AREA UNTIL TUESDAY EVE. THIS LEAVES HIGH THICKNESSES...850MB TEMPS OF 17-19C...AND DEW POINT TEMPS WELL INTO THE 70S...BOTH MONDAY AND TUESDAY. TEMPS ON MONDAY WILL SOAR INTO THE MID 90S EVERYWHERE EXCEPT THE IMMEDIATE BEACHES...AND WILL ONLY BE A DEGREE OR SO COOLER ON TUESDAY. THIS REPRESENTS A SEVERAL-DEGREE JUMP IN FORECAST HIGHS FOR TUESDAY...BUT GUIDANCE HAS BACKED OFF ON THE LONGITUDINAL PROGRESSION OF THE COLD FRONT DURING TUESDAY...SO A JUMP IS REQUIRED. THESE TEMPS WILL COMBINE WITH THE HIGH DEWPOINTS...CAUSING HEAT INDICES TO APPROACH 105 ON MONDAY...AND AROUND 100 ON TUESDAY. LOWS BOTH NIGHTS WILL BE SIMILARLY WARM...MID/UPR 70S MONDAY NIGHT...AND A FEW DEGREES COOLER ON TUESDAY. WHILE HEAT WILL BE THE BIG CONCERN EARLY WEEK...CONVECTION WILL BECOME INCREASINGLY WIDESPREAD INTO TUESDAY AHEAD OF THE ADVANCING COLD FRONT. MONDAY WILL FEATURE ONLY ISOLATED STORMS...FOCUSED PRIMARILY ON THE TYPICAL SEA BREEZE AND PIEDMONT TROUGH BOUNDARIES...BUT LOWERING THICKNESSES AND THE COLD FRONT WILL CAUSE MORE WIDESPREAD STORMS TUESDAY...AND ESPECIALLY TUESDAY NIGHT WHEN COLUMN SATURATION OCCURS AND THE COLD FRONT REACHES THE ILM CWA. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 330 AM SUNDAY...COOL AND WET CONDITIONS ARE EXPECTED FOR THE ENTIRETY OF THE LONG TERM AS A HIGHLY AMPLIFIED 500MB PATTERN DRIVES AN ANOMALOUS TROUGH INTO THE EASTERN CONUS. BENEATH THIS TROUGH...A COLD FRONT WILL PUSH INTO THE LOCAL AREA BY THE BEGINNING OF THE EXTENDED...AND THEN STALL ACROSS THE EAST COAST. ALTHOUGH THIS TROUGH IS QUITE STRONG...CAUSING LOWERED THICKNESSES ALL WAY TO NEAR CUBA (!)...IT REMAINS POSITIVELY TILTED WITH AN AXIS FROM SW TO NE. THIS IS UNFORTUNATE FOR THE LOCAL AREA SINCE THAT CAUSES FLOW TO BECOME BOUNDARY PARALLEL...HENCE CAUSING THE FRONT TO STALL...PRETTY MUCH OVERHEAD...INTO NEXT WEEKEND. AT THE SAME TIME...MOIST FLOW FROM THE GULF OF MEXICO WILL REMAIN TAPPED AS THE SW FLOW ORIGINATES FROM THAT AREA...AND THUS AN EXTENDED PERIOD OF WET WEATHER IS ANTICIPATED. WPC HAS 2-4" OF QPF ACROSS THE AREA NEXT WEEK...AND ALTHOUGH THERE IS SOME UNCERTAINTY INTO HOW MUCH THE FRONT WILL WAVER INLAND/OFFSHORE...EXPECT THE MAJORITY OF THE PERIOD TO FEATURE SLIGHTLY BELOW NORMAL TEMPS AND GOOD CHANCES FOR PRECIP. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... AS OF 12Z...LBT IS THE ONLY TERMINAL NOT VFR AT THIS TIME...WITH STRATUS COMING IN AND OUT. LOOK FOR VFR AT ALL TERMINALS NO LATER THAN 13Z. ALONG THE COAST...THERE COULD BE MVFR TROPICAL LIKE CU THIS MORNING...BUT SHOULD STAY SCATTERED FOR THE MOST PART. THERE IS ENOUGH MOISTURE IN PLACE TO SUPPORT SCATTERED CONVECTION ALONG THE SEA BREEZE BY AROUND MIDDAY...PUSHING INLAND BY 19-20Z. BRIEF DOWNPOURS ARE POSSIBLE...BUT THEY WILL BE ISOLATED IN NATURE. SOUTHWEST FLOW WILL PICK UP IN THE AFTERNOON IN ADVANCE OF THE NEXT SYSTEM WHICH WILL BRING INCREASED CONVECTION IN A DAY OR TWO. THE SOUTHWEST FLOW SHOULD BE STRONG ENOUGH TONIGHT TO PRECLUDE FOG. EXTENDED OUTLOOK...INCREASING CHANCES FOR SHOWERS/TSTMS AND MVFR CONDITIONS TUESDAY THROUGH THURSDAY AS A COLD FRONT STALLS OVER THE CAROLINAS. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 2 AM SUNDAY...WEAK GRADIENT AND RADIATIONAL COOLING INLAND MAY ALLOW FOR LAND BREEZE DEVELOPMENT EARLY THIS MORNING. THIS WOULD CAUSE W TO NW FLOW NEAR THE COAST WHILE WINDS ACROSS THE REMAINDER OF THE WATERS WILL BE LIGHT AND FROM THE S-SW. WEAK GRADIENT AND LARGE SCALE SOUTHERLY FLOW WILL ALLOW FOR DEVELOPMENT OF SEA BREEZE BY EARLY AFTERNOON...ENHANCING ONSHORE FLOW NEAR THE COAST. WINDS WILL BE 10 KT OR LESS AWAY FROM THE COAST AND 10 TO 15 KT NEAR SHORE. SEAS WILL RUN 2 FT THROUGH THE AFTERNOON/EVENING. GRADIENT BECOMES A LITTLE MORE DEFINED OVERNIGHT WITH SOUTHWEST FLOW APPROACHING 15 KT. THIS WILL PUSH SEAS TO 3 FT BY THE END OF THE PERIOD. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 330 AM SUNDAY...HIGH PRESSURE WELL OFFSHORE...AND A COLD FRONT APPROACHING FROM THE WEST...WILL KEEP THE WATERS SANDWICHED IN BETWEEN THROUGH THE PERIOD. THIS DRIVES A PINCHED GRADIENT...AND FORCES SW WINDS TO INCREASE TO AROUND 20 KTS MUCH OF THE BEGINNING OF THE WEEK. THESE STRONG WINDS WILL DRIVE WAVE HEIGHTS UP TO 3-5 FT MUCH OF THE SHORT TERM...POSSIBLY REACHING 6 FT ON TUESDAY. CAUTIONARY STATEMENTS ARE LIKELY FOR A PORTION OF THE EARLY-WEEK TIME-FRAME...AND CONDITIONS NECESSITATING AN SCA MAY BE POSSIBLE. LONG TERM /WEDNESDAY THROUGH THURSDAY/... AS OF 330 AM SUNDAY...HIGH PRESSURE CENTERED WELL OFFSHORE WILL GRADUALLY LOSE ITS INFLUENCE OVER THE WATERS AS A COLD FRONT STALLS ACROSS THE AREA. AT THIS TIME EXPECT THE FRONT TO REMAIN JUST WEST OF THE WATERS...BUT WILL HAVE THE EFFECT OF WEAKENING THE GRADIENT...AND THUS SW WINDS WILL EASE FROM AROUND 15 KTS WEDNESDAY...TO 10 KTS OR LESS ON THURSDAY. THIS WILL CAUSE WAVE HEIGHTS TO SLOWLY FALL FROM 3-5 FT EARLY...TO 2-4 FT LATE THURSDAY...EVEN AS A SE GROUND SWELL BEGINS TO AMPLIFY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...JDW NEAR TERM...III SHORT TERM...JDW LONG TERM...JDW AVIATION...43 MARINE...III/JDW

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