Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 302351 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 751 PM EDT SUN AUG 30 2015 .SYNOPSIS... A WAVE OF LOW PRESSURE WILL MOVE NORTH FROM FLORIDA ALONG THE CAROLINA COASTLINE THROUGH MONDAY NIGHT. TROPICAL MOISTURE STREAMING NORTHWARD INTO THE CAROLINAS WILL BRING A GOOD CHANCE OF RAIN THROUGH TUESDAY. WEAK HIGH PRESSURE WILL COVER THE AREA THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 730 PM SUNDAY...WATER VAPOR SATELLITE IMAGERY SHOWS A PLUME OF DEEP TROPICAL MOISTURE MOVING NORTH ACROSS FLORIDA AND ACROSS THE EASTERN CAROLINAS. PRECIPITABLE WATER VALUES IN EXCESS OF 2.0 INCHES PEAK AT 2.5 INCHES NEAR CONVECTION OFF THE GEORGIA COAST. THIS IS MOISTURE ASSOCIATED WITH FORMER TROPICAL STORM ERIKA. AT THE SURFACE A WAVE OF LOW PRESSURE EXTENDING NORTHWARD FROM FLORIDA INTO THE CAROLINA COASTAL PLAIN SHOULD SHARPEN UP OVERNIGHT. DUSTING OFF MY WINTERTIME ISENTROPIC LIFT PROCEDURES AND EXAMINING THE 310K THETA SURFACE (NEAR 700 MB) REVEALS A GOOD AMOUNT OF LIFT DEVELOPING OVERNIGHT... SUFFICIENT TO PRODUCE WIDESPREAD RAIN OR SHOWERS ACROSS THE ENTIRE FORECAST AREA. POPS HAVE BEEN INCREASED TO 90-100 PERCENT. FORECAST SOUNDINGS SHOW A WARM NOSE APPEARING AROUND 650 MB OVERNIGHT IN THE MIDST OF A WARM ADVECTION JET OUT AHEAD OF A RATHER IMPRESSIVE UPPER DISTURBANCE MOVING NORTH THROUGH THE SOUTHERN APPALACHIANS. NEAR AND ABOVE THIS WARM NOSE LAPSE RATES ARE GREATER THAN MOIST ADIABATIC AND I HAVE INCLUDED THE MENTION OF ISOLATED THUNDERSTORMS IN THE FORECAST. WITH SUCH HIGH PRECIPITABLE WATER VALUES AND SUPPORT FOR PRECIPITATION PROVIDED BY BOTH SYNOPTIC AND CONVECTIVE TRIGGERS...LOCALIZED HEAVY RAINFALL COULD DEVELOP OVERNIGHT. AREAL RAINFALL FORECASTS NOW INCLUDE 0.5 TO 0.8 INCH TOTALS NOW THROUGH 8 AM MONDAY...WITH AREAS BENEATH SUSTAINED CONVECTION OBVIOUSLY PICKING UP MORE. TEMPERING THIS HEAVY RAIN THREAT WILL BE THE FACT THE BEST LIFT SHOULD OCCUR AT A RATHER HIGH ALTITUDE (AT AND ABOVE 700 MB) WITH MOISTURE EXISTING BELOW THIS LAYER NOT DIRECTLY BEING INVOLVED IN PRECIP GENERATION. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 PM SUNDAY...PRIMARY HEADLINE REMAINS GOOD RAIN POTENTIAL SETTING UP FOR NE SC AND SE NC AS AN UPPER LOW EVIDENT IN VAPOR CHANNEL THIS AFTERNOON DRIVES DEEP TROPICAL MOISTURE NORTHWARD. MARINE CONVECTIVE SYSTEMS CURRENTLY OFFSHORE OF FLORIDA AND GEORGIA WILL TRANSPORT A RICH SUPPLY OF DISTURBED AIR OVER A NOCTURNALLY BUOYANT OCEAN LATE TONIGHT INTO MONDAY MORNING. RAIN CHANCES MAY CUT OFF SHARPLY INLAND MONDAY AS DRY AIR INTRUSION ENTRAINED INTO THE UPPER LOW SPREADS MORE CAPPING INLAND. DUE TO HIGH PRECIPITABLE WATERS IN PLACE OVER THE NEXT 36-48 HOURS HOWEVER...RAIN MAY BE HEAVY AT TIMES THROUGH AT LEAST TUESDAY MORNING...AND FAVORED CLOSER TO THE COAST. WPC QPF GRAPHICS THROUGH WED 00Z/TUE 8PM SHOW 2-3 INCHES ALONG THE SC COAST AND 1-2 INCHES ELSEWHERE...BUT LESS THAN AN INCH WEST OF I-95. CLOUDS WILL KEEP MAXIMUMS BELOW NORMAL MONDAY AND TUESDAY FOR THE EASTERN AND CENTRAL ZONES BUT CLOSER TO AVERAGE WELL INLAND. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 3 PM SUNDAY...THE UPPER LOW ACROSS THE GULF COAST...WHICH WAS HELPING FUNNEL DEEP MOISTURE ASSOCIATED WITH THE REMNANTS OF ERIKA...WEAKENS BY THE START OF THE PERIOD. IT LOOKS LIKE WHAT IS LEFT OF ERIKA WILL BE A DRIFT ACROSS GEORGIA MID AND LATE WEEK GIVEN THE WEAK PRESSURE PATTERN. A TROUGH WILL EXTEND NE ALONG THE COAST...AND THIS WILL HELP TO KEEP UNSETTLED WEATHER ACROSS THE CAROLINAS MID WEEK. AN UPPER RIDGE WILL BEGIN TO EXPAND ACROSS THE SOUTHEAST AND SOUTHERN TIER OF THE COUNTRY MID AND LATE WEEK. OVERALL... PRECIPITABLE WATER VALUES ARE HIGHER MID WEEK...SLOWLY LOWERING LATE WEEK AND FOR THE WEEKEND. THIS SUGGESTS HIGHER POPS...ESPECIALLY WED- THU TIME FRAME AND LOWEST POPS DURING THE WEEKEND. HOWEVER...SURFACE HIGH PRESSURE TO OUR N MAY RIDGE STRONGLY TO OUR W...THUS ALLOWING FOR A COASTAL TROUGH TO DEVELOP/STRENGTHEN. THIS SCENARIO WOULD BRING AT LEAST SCATTERED CONVECTION TO THE COAST OR JUST OFFSHORE EVEN LATE IN THE PERIOD. AT THIS TIME...NOT SEEING ENOUGH SIGNALS TO GO ABOVE CHANCE CATEGORY THROUGHOUT ALTHOUGH LATER FORECASTS MAY FIND JUSTIFICATION FOR AT LEAST LIKELY POPS AS THE FINER DETAILS IN BOTH TIME AND SPACE CRYSTALLIZE. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... AS OF 00Z...EXPECT A MIXTURE OF VFR/MVFR/IFR AS ISOLATED TO SCATTERED SHOWERS...LOWER CIGS...AND AREAS OF FOG AFFECT THE AREA TONIGHT THROUGH MONDAY LATE AFTERNOON. LATEST RADAR DEPICTS SHOWERS MOVING ACROSS PORTIONS OF THE FORECAST AREA...WITH OBSERVATIONS SEEING A MIXTURE OF VFR/MVFR/IFR DUE TO NOT ONLY SHRA ACTIVITY...BUT LOW CIGS AND AREAS OF FOG AS WELL. EXPECT THIS TO CONTINUE THROUGH THE OVERNIGHT HOURS...WITH RAINFALL INCREASING AS THE ATMOSPHERIC COLUMN INCREASINGLY BECOMES SATURATED. WINDS WILL BE LIGHT. INTO MONDAY...SHOWERS WILL CONTINUE WITH A GRADUAL IMPROVEMENT OF CONDITIONS TO MVFR/AREAS OF VFR IN THE MORNING HOURS. SOUTHEAST WINDS WILL INCREASE TO AOB 10 KTS WITH GUSTS ALONG THE COAST UP TO 18 KTS THROUGH THE LATE MORNING HOURS. EXTENDED OUTLOOK...SLOW MOVING LOW PRESSURE MOVING UP THE COAST WILL GIVE US UNSETTLED WEATHER THROUGH WEDNESDAY...WITH INTERMITTENT SHOWERS AND MVFR/IFR CEILINGS. A BIT BETTER FOR THURSDAY AND FRIDAY WITH ISOLATED MAINLY AFTERNOON SHOWERS. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 730 PM SUNDAY...A WEAK BUBBLE OF HIGH PRESSURE CENTERED NEAR CAPE LOOKOUT WILL DISSIPATE OVER THE NEXT SEVERAL HOURS AS A DEVELOPING WAVE OF LOW PRESSURE MOVES NORTH FROM FLORIDA. MOISTURE ASSOCIATED WITH FORMER TROPICAL STORM ERIKA IS INVOLVED IN THIS SYSTEM...AND WILL BRING A RAINY NIGHT FOR MARINERS ALONG THE CAROLINA COAST. RAIN CHANCES ARE 100 PERCENT...WITH THE HEAVIEST ACTIVITY EXPECTED AFTER MIDNIGHT AS STORMS OFF THE GEORGIA COAST MOVE NORTHWARD. A WARM FRONT WILL SHARPEN UP JUST INLAND FROM THE COAST OVERNIGHT...WITH SOUTHEAST WINDS INCREASING TO NEAR 15 KNOTS ALONG THE SC COAST...10-15 KT FOR NC. SEAS CURRENTLY RANGING FROM 2- 3 FEET (PRIMARILY IN 10 SECOND SOUTHEAST SWELL) MAY BUILD BY ANOTHER FOOT OVERNIGHT. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 PM SUNDAY...MARINE CONDITIONS WILL WORSEN INTO MONDAY AS RAIN REDUCES VSBYS AND SE WINDS KEEP SEAS ELEVATED 3-4 FT SEAS AND AS HIGH AS 5 FT OUTER PORTION. AN EXERCISE CAUTION STATEMENT MAY BE NEEDED FOR THE SC WATERS WHERE STRONGER SE WINDS OF 17-21 KT MAY OCCUR MUCH OF MONDAY. ISOLATED TSTMS WILL LIKELY GREET THE WATERS MONDAY MORNING AND AGAIN INTO TUESDAY. SEAS MONDAY AND TUESDAY ESE WAVES 3-5 FT EVERY 8-9 SECONDS...HIGHEST OFFSHORE. SE WIND CHOP WILL BE STRONGEST MONDAY ALONG THE SC COAST AND AN EXERCISE CAUTION STATEMENT MAY BE NEEDED. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 3 PM SUNDAY...A WEAK PRESSURE GRADIENT IS EXPECTED ACROSS THE WATERS MID AND LATE WEEK. A TROUGH IS EXPECTED TO EXTEND NE ALONG THE SOUTHEAST COAST FOR MUCH OF THE PERIOD. THIS FEATURE LOOKS MOST PRONOUNCED WED- THU. WIND SPEEDS ARE EXPECTED TO GENERALLY BE 10 KT OR LESS THROUGH THE PERIOD. THE DIRECTION WILL BE MAINLY EASTERLY OR SE DURING THE AFTERNOON AND EVE HOURS. THE LATE NIGHT AND MORNING LAND BREEZE WILL DISRUPT THE FLOW TO MORE OF AN OFFSHORE DIRECTION. SEAS WILL BE MAINLY 2 FT. A 8 TO 9 SECOND SE SWELL WILL BE PRESENT...PERHAPS SLIGHTLY STRONGER MID WEEK AS COMPARED TO LATE WEEK. WINDS AND SEAS MAY BE HIGHER IN PERSISTENT THUNDERSTORMS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...MJC LONG TERM...RJD AVIATION...SGL

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