Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 301730 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 130 PM EDT WED JUL 30 2014 .SYNOPSIS... SEASONABLE WEATHER WILL CONTINUE THROUGH THURSDAY AS CANADIAN HIGH PRESSURE SETTLES ACROSS THE AREA. A COASTAL FRONT WILL LIFT NORTH ACROSS THE AREA FRIDAY AND INTO THE WEEKEND...BRINGING GOOD RAIN CHANCES INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 130 PM WEDNESDAY...SOME MOISTURE REMAINS AVAILABLE IN PRIMARILY THE LOWER LEVELS THROUGH THE REMAINDER OF THE AFTERNOON. MEANWHILE WATER VAPOR IMAGERY SHOWS THE DRIEST AIR ACROSS NC WITH A DEEP PLUME FAR OFF THE COAST OVER THE WESTERN ATLANTIC. AT THE SURFACE...WEAK HIGH PRESSURE REMAINS IN CONTROL AS IT RIDGES IN FROM THE NORTH AND AT THE COAST A WEAK NORTHEAST RESULTANT BOUNDARY DEVELOPS. REGARDING CONVECTION...GIVEN THE LIMITED MOISTURE AND ONLY MARGINAL INSTABILITY WILL FORECAST ISOLATED SHRA/TSRA WITH THE HIGHEST (ALBEIT LOW) PROBABILITIES ACROSS THE SOUTHERN ZONES. THE ISOLATED CONVECTION IS EXPECTED TO DISSIPATE THIS EVENING WITH THE LOSS OF HEATING. THUS FOR THE OVERNIGHT...MOSTLY CLEAR TO PARTLY CLOUDY SKIES ON TAP WITH LOWS BELOW CLIMO (MID 60S FAR INLAND TO THE UPPER 60S INLAND COASTAL COUNTIES). && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM WEDNESDAY...COOL WEATHER WILL CONTINUE FOR THE SHORT TERM THANKS TO A CLOSED LOW PRESSURE NEAR THE HUDSON BAY MAINTAINING AN ANOMALOUSLY STRONG MID-LEVEL TROUGH ACROSS THE EAST. THIS FEATURE WILL VERY GRADUALLY WEAKEN AND LIFT TO THE NORTHEAST BY THE WKND...AND THUS SUBTLE THICKNESS INCREASES WILL OCCUR...BUT AT THE SAME TIME THIS WILL ALLOW WINDS TO BACK MORE TO THE S/SW OFF THE SURFACE...INCREASING COLUMN MOISTURE. PWATS THURSDAY AROUND 1.75 INCHES ARE RIGHT AROUND SEASONABLE VALUES FOR THE BEGINNING OF AUGUST...AND SCATTERED SHOWERS/TSTMS WILL BE POSSIBLE THURSDAY. FRIDAY IS EXPECTED TO BE THE WETTER DAY HOWEVER...AS COASTAL TROUGH/WARM FRONT BEGIN TO LIFT BACK TOWARDS THE COAST...LIKELY MOVING ONSHORE LATE FRIDAY. PWATS RISE TO AROUND 2 INCHES...WHICH WILL COMBINE WITH SURFACE CONVERGENCE ALONG THE BOUNDARY...AND CONTINUED UPPER DIFFLUENCE WITHIN THE JET-STREAK EMBEDDED DOWNWIND OF THE LARGE SCALE TROUGH...TO CREATE A GOOD CHANCE FOR SHOWERS AND STORMS. THERE WILL BE SOME DIURNAL ENHANCEMENT/NOCTURNAL DECREASE OF THE CONVECTION FRIDAY...BUT DO EXPECT SHOWERS TO CONTINUE THROUGHOUT FRIDAY NIGHT. TEMPS WILL REMAIN BELOW NORMAL FOR THE DATE...WITH MID 80S EXPECTED THURSDAY...ALTHOUGH A FEW SPOTS IN THE PEE DEE REGION OF SC MAY APPROACH 90. ALTHOUGH THICKNESSES RISE FRIDAY...CLOUDS AND PRECIP WILL LIMIT WARMING...AND THUS HIGHS WILL BE A DEGREE OR TWO COOLER THAN THURSDAY. MINS BOTH NIGHTS WILL FALL INTO THE UPPER 60S INLAND...AROUND 70 AT THE COAST. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 300 AM WEDNESDAY...A WET PERIOD EXPECTED THE FIRST HALF OF THE LONG TERM...MAKING THE FIRST WEEKEND OF AUGUST COOL AND UNSETTLED. LARGE UPPER TROUGH WHICH HAS BEEN PLAGUING THE EASTERN CONUS FOR SOME TIME WILL FINALLY...SLOWLY...BEGIN TO ERODE THANKS TO THE WEAKENING OF THE PARENT VORTEX...AND THE AMPLIFICATION OF THE RIDGE ACROSS THE ATLANTIC OCEAN. WHILE THIS RIDGE WILL EVENTUALLY OVERCOME THE PERSISTENT TROUGH ACROSS THE EAST...IT WILL LIKELY TAKE UNTIL TUESDAY FOR ANY NOTICEABLE WARMING/DRYING TO OCCUR LOCALLY...AND TEMPS WILL REMAIN BELOW NORMAL THROUGH THE PERIOD. THE REASON FOR THIS IS BECAUSE AS THE TROUGH BEGINS RECEDE TO THE WEST...A COASTAL TROUGH/WARM FRONT WILL STALL NEAR THE AREA DURING THE WEEKEND. THIS PROVIDES STRONG LOW-LEVEL MOIST ADVECTION...WHILE MID-LEVEL MOIST ADVECTION OCCURS ON INCREASING S/SW FLOW DOWNWIND OF THE TROUGH AXIS. THIS PRODUCES PWATS OVER TWO INCHES...WHICH COMBINE WITH SURFACE CONVERGENCE AND UPPER DIFFLUENCE WITHIN THE JET STREAK AROUND THE BASE OF THE TROUGH TO CREATE SCATTERED TO WIDESPREAD SHOWERS AND THUNDERSTORMS SATURDAY...SUNDAY...AND EVEN INTO MONDAY. FINALLY BY TUESDAY THE SURFACE TROUGH WASHES OUT...RIDGING TAKES HOLD ALOFT...AND MORE SEASONABLE WEATHER DEVELOPS FOR THE MIDDLE OF NEXT WEEK. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 18Z...VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE VALID PERIOD. SATELLITE IMAGERY SHOWS CU FIELD FILLING IN ACROSS THE CWA THIS AFTN WITH BASES GENERALLY 3-6KFT. THESE CLOUDS WILL PERSIST THROUGH THE REST OF TODAY WITH EAST WINDS AOB 10 KT. ALTHOUGH THE FCST SOUNDINGS ARE VERY DRY ABOVE 700 MB...RADAR IMAGERY THIS AFTN INDICATES ENOUGH UPPER SUPPORT EXISTS FOR A FEW ISOLATED SHOWERS TO DEVELOP. BUT GIVEN THE VERY LIMITED AREAL COVERAGE...HAVE NOT MENTIONED ANY VCSH WITH THIS ISSUANCE. EXPECT INCREASING CIRRUS OVERNIGHT AS WINDS BECOME E-NE 5 KT OR LESS. HAVE LOW CONFIDENCE FOR TEMPO MVFR VSBYS EARLY THU MORNING AT KFLO/KLBT. THOUGH THE WIND SPEEDS ARE FORECAST TO DROP OUT...INCREASING CIRRUS MAY BE ENOUGH TO KEEP VSBYS AT VFR LEVELS INLAND. WILL NOT INCLUDE ANY BR ATTM. VFR WILL PERSIST INTO THU WITH EAST WINDS AOB 10 KTS. EXTENDED OUTLOOK...INCREASING CHANCES FOR SHRA/TSRA AND PERIODS OF MVFR CONDITIONS FRIDAY THROUGH MONDAY AS A FRONT STALLS OVER THE EASTERN CAROLINAS. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 130 PM WEDNESDAY...NORTHEASTERLY FLOW PREVAILS ACROSS THE COASTAL WATERS EARLY THIS AFTERNOON. WITH THE HEATING OF THE DAY AND SUBSEQUENT NORTHEASTERLY RESULTANT EXPECTED TO DEVELOP THE FLOW SHOULD VEER AROUND TO AN EASTERLY DIRECTION THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING. OVERNIGHT THE FLOW SHOULD BACK SLIGHTLY WITH SPEEDS AROUND 10 KNOTS OR LESS. SEAS WILL RANGE FROM 2 FT NEAR THE COAST TO 3 FT THROUGH TONIGHT. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM WEDNESDAY...STALLED COLD FRONT/COASTAL TROUGH WELL OFFSHORE WILL BE PUSHED BACK TOWARDS THE COAST THURSDAY BEFORE MOVING ONSHORE DURING FRIDAY. THE GRADIENT WILL REMAIN WEAK NEAR THIS FEATURE...WITH WINDS AROUND 10 KTS THROUGH THE PERIOD...BUT A VEERING FROM THE EAST THURSDAY...TO SE ON FRIDAY...WILL OCCUR BEHIND THIS BOUNDARY. SEVERAL WAVE GROUPS WILL EXIST WITHIN THE SPECTRUM...BUT A LOW AMPLITUDE SE GROUND SWELL AND EAST AND SOUTHEAST WIND WAVES WILL COMBINE TO PRODUCE 2-3 FT SEAS THROUGH THE PERIOD. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 300 AM WEDNESDAY...COASTAL TROUGH/WARM FRONT WILL LIFT NW OF THE WATERS BY EARLY SATURDAY...AND REMAIN INLAND DURING THE WKND. WINDS BEHIND THIS FEATURE WILL VEER SLOWLY FROM SE TO SW...AT SPEEDS OF 10-15 KTS. WAVE HEIGHTS WILL BE PREDOMINANTLY 2-3 FT THROUGH THE EXTENDED...BUT SOME 4 FT SEAS ARE POSSIBLE SUNDAY THANKS TO THE LONGER SPATIAL FETCH FROM THE S/SE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...SRP SHORT TERM...JDW LONG TERM...JDW AVIATION...BJR/SRP

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