AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 137 AM EDT FRI JUL 8 2011 .SYNOPSIS... BERMUDA HIGH PRESSURE WILL MAINTAIN A MOIST SOUTHERLY FLOW ACROSS THE EASTERN CAROLINAS INTO THE WEEKEND. TROPICAL MOISTURE MOVING NORTHWARD ACROSS THE EASTERN CAROLINAS WILL BRING SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS INTO THE WEEKEND. SOME OF THIS RAIN WILL BE HEAVY AT TIMES. BERMUDA HIGH PRESSURE WILL BUILD BACK ACROSS THE AREA EARLY NEXT WEEK. A COLD FRONT MAY APPROACH THE AREA DURING THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM THURSDAY...A BREAK IN THE SUBTROPICAL RIDGE AXIS ACROSS THE SOUTHEASTERN U.S. HAS ALLOWED DEEP TROPICAL MOISTURE TO POOL ACROSS THE EASTERN CAROLINAS. PRECIPITABLE WATER VALUES AROUND 2.00 INCHES AND WIDESPREAD MODERATE INSTABILITY ARE TYPICAL FOR A TROPICAL AIRMASS LIKE THIS ONE. CONVECTION HAS LARGELY AVOIDED OUR FORECAST AREA THIS EVENING...MAINLY AFFECTING AREAS BETWEEN COLUMBIA AND CHARLOTTE...AND ANOTHER LARGE CLUSTER FROM RALEIGH TO GOLDSBORO AND KINSTON. FOR THE OVERNIGHT PERIOD RAIN CHANCES AWAY FROM THE COAST APPEAR QUITE LOW...20 PERCENT OR LESS. THIS IS DUE TO A SLOWLY STABILIZING NOCTURNAL AIRMASS AND THE SEABREEZE BOUNDARY NOW WELL WEST OF OUR FORECAST AREA. AT THE COAST RAIN CHANCES ARE QUITE A BIT HIGHER... PARTICULARLY FOR THE COASTAL CAPE FEAR AREA IN NC WHERE PRECIP CHANCES RISE TO 50-60 PERCENT ALONG THE BEACHES. SURFACE-BASED INSTABILITY REMAINS QUITE HIGH OVER THE OCEAN WHERE AIR TEMPS WILL REMAIN IN THE 80S WITH DEWPOINTS 75-77. RADAR LOOPS SHOW PLENTY OF ACTIVITY OFFSHORE THAT SHOULD PERIODICALLY AFFECT THE NC COAST TONIGHT. THESE ARE TROPICAL SHOWERS CONTAINING LITTLE LIGHTNING BUT BRIEFLY TORRENTIAL RAINFALL. ONE VERY PICTURESQUE CUMULONIMBUS JUST OFF WRIGHTSVILLE BEACH AT SUNSET WAS BARELY 20 KFT TALL ON RADAR CROSS-SECTIONS YET WAS STILL PRODUCING HEAVY RAINFALL. LOWS TONIGHT WILL REMAIN QUITE WARM GIVEN THE AMOUNT OF MOISTURE IN THE AIR...AND THE PRESENCE OF A WEAK LOW-LEVEL JET WHICH SHOULD HELP KEEP THE BOUNDARY LAYER FROM FULLY DECOUPLING OVERNIGHT. WE ARE EXPECTING 72-76 INLAND...WITH UPPER 70S WITHIN A FEW MILES OF THE BEACHES. UNLESS SIGNIFICANT AREAS OF HEAVY RAIN DEVELOP NEAR SHORE SOME NC BEACHES MIGHT NOT DIP BELOW 80 DEGREES TONIGHT. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... AS OF 3 PM THURSDAY...TROPICAL-LIKE MOISTURE STREAMING NORTHWARD ACROSS THE EASTERN CAROLINAS SHOULD BRING AN INCREASING RISK FOR SHOWERS AND THUNDERSTORMS. THE PRIMARY CHARACTERISTIC OF THIS CONVECTION WILL BE VERY HEAVY RAIN WITH PRECIPITABLE WATER VALUES AROUND 2.25 INCHES. THE RISK FOR AT LEAST MINOR FLOODING WILL BE ON THE INCREASE...ESPECIALLY IN THOSE AREAS WHERE HEAVY RAIN HAS OCCURRED OVER THE LAST FEW DAYS. A WET MICROBURST WILL BE CAPABLE OF BRINGING STRONG WINDS TO THE SURFACE...ESPECIALLY FRI AFTERNOON. A WEAK TROUGH WILL LIMP INTO THE AREA LATE SAT NIGHT. MAY SEE LOW STRATUS OR FOG DEVELOP AS WEAK FRONTAL BOUNDARY LIMPS INTO THE AREA LATE SAT NIGHT AND SUN MORNING...SHIFTING LIGHT WINDS TO NORTHERLY. THE LARGEST WILDFIRES REMAIN ACROSS NORTHERN PENDER COUNTY...IN THE HOLLY SHELTER GAME LAND AND NEAR THE BLADEN-CUMBERLAND COUNTY LINE. IF THESE NORTHERLY WINDS DO MATERIALIZE...SMOKE PLUMES WILL CHANGE THEIR ORIENTATION...BLOWING SMOKE FROM N TO S...INSTEAD OF FROM S TO N WHICH HAS BEEN THE CASE FOR MANY DAYS NOW. GIVEN THE EXTENT OF CLOUD COVER EXPECTED...AND CONSIDERING THE DEPTH OF MOISTURE...TENDED TO GO ABOVE GUIDANCE ON MINIMUMS AND AT OR BELOW THE COOLEST GUIDANCE FOR MAXIMUMS. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 3 PM THURSDAY...MID LEVEL RIDGE BUILDS OVER TN AND OHIO VALLEY ON SUNDAY AS WELL AS ACRS THE BAHAMAS. THERE IS SOME MODEL AGREEMENT THAT A SHORTWAVE SLIDES SOUTHWARD BETWEEN THE TWO AND THIS MAY BRING ONE LAST DAY OF SLIGHTLY ENHANCED RAINFALL CHANCES BEFORE THE LONG TERM SHIFTS LARGELY BACK TO A FORECAST OF CLIMATOLOGY. THIS UPPER FORCING WILL BE BOOSTED BY A SURFACE TROUGH LINGERING JUST INLAND FROM THE COAST AS WELL AS PLENTIFUL OUTFLOW BOUNDARIES FROM SATURDAYS POTENTIALLY ACTIVE DAY OF CONVECTION. AFTERNOON HIGHS WILL BE NEAR CLIMO OR JUST A FEW DEGREES BELOW ON ACCOUNT OF THE POSSIBILITY OF WIDESPREAD CLOUD COVER. AS THIS MID LEVEL FEATURE MOVES OFF INTO THE GOMEX HEIGHTS RISE LOCALLY AND SOME DRYING SOUTH OCCUR. THERE WILL BE LITTLE CHANGE IN SURFACE AND LOW LEVEL AIRMASS...AS TYPICAL FOR JULY. THIS WILL STILL LEAVE THE DOOR OPEN FOR VERY ISOLATED COVERAGE OF AFTERNOON THUNDERSTORMS ALONG MESOSCALE BOUNDARIES AND TEMPERATURES WILL AVERAGE A FEW DEGREES ABOVE CLIMATOLOGY MONDAY AND TUESDAY. MODEL AGREEMENT IN DEPICTING A COLD FRONT APPROACHING AND PERHAPS EVEN TRAVERSING THE AREA WEDNESDAY OR WEDNESDAY NIGHT APPEARS TO WARRANT SOME INCREASED CLOUD COVER AND RAIN CHANCES. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 06Z...MODERATE CONFIDENCE IN FORECAST DUE TO CIG RESTRICTIONS BEFORE DAYBREAK AND CONVECTION IN THE AFTERNOON. SEEING CURRENT RADAR TRENDS AND TROPICAL MOISTURE BEING ADVECTED INLAND...EXPECT TO SEE SHOWER ACTIVITY DEVELOP OVER THE COASTAL TERMINALS AND LIKELY MAKE ITS WAY INLAND BY THE MORNING. MAIN AVIATION IMPACT AS A RESULT OF THIS AMPLE LOW LEVEL MOISTURE WOULD BE DEVELOPING MVFR...POSSIBLY IFR...CIGS. INLAND TERMINALS HAVE A BETTER SHOT AT SEEING IFR SIMPLY GIVEN PERSISTENCE THE PAST COUPLE OF NIGHTS. FOG IS LOOKING UNLIKELY AT THIS POINT GIVEN NOCTURNAL LLJ AND NO SIGNIFICANT RAINFALL PROVIDED EARLIER. THUS HAVE REFLECTED THIS IN THE TAF. AFTER SUNRISE... RESTRICTIONS SHOULD LIFT. CONVECTION WILL LIKELY PERSIST THROUGHOUT THE AFTERNOON AND MAY CAUSE PERIODS OF REDUCED VSBY WITHIN HEAVIEST RAINFALL. TIMING AND LOCATIONS ARE UNCERTAIN ATTM...SO WILL JUST INCLUDE VCTS AND WAIT UNTIL LATER ISSUANCES TO SPECIFY. WINDS WILL REMAIN SOUTHERLY THROUGHOUT THE DAY WITH SPEEDS AROUND 10-15 KNOTS...A BIT STRONGER AND GUSTIER AT THE COAST DUE TO A TIGHTENED PG. STORM ACTIVITY MAY PERSIST WELL INTO THE EVENING. EXTENDED OUTLOOK...WIDESPREAD SHOWERS AND THUNDERSTORMS LIKELY THROUGHOUT THE WEEKEND. PRECIP CHANCES DECREASE EARLY NEXT WEEK. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM THURSDAY...RADAR SHOWS PLENTY OF MARINE SHOWER AND THUNDERSTORM ACTIVITY WITHIN ABOUT 50 MILES OF CAPE FEAR. THIS HAS ACTUALLY DEVELOPED A LITTLE FASTER THAN MODELS HAD INDICATED. THE MARINE ZONE FORECAST FOR THE OVERNIGHT PERIOD READS `SHOWERS AND TSTMS LIKELY` FOR THE NC COASTAL WATERS...ALTHOUGH IN OUR DIGITAL FORECAST GRIDS RAIN CHANCES ARE NEAR 100 PERCENT BEYOND 10 MILES FROM SHORE NEAR AND EAST OF CAPE FEAR. THESE ARE TROPICAL SHOWERS CONTAINING LITTLE LIGHTNING BUT TREMENDOUS RAINFALL RATES AND SUBSEQUENT VISIBILITY RESTRICTIONS. CONVECTION IS ADDING SOME GUSTINESS AND VARIABILITY TO THE WINDS...BUT THE SYNOPTIC WIND APPEARS TO BE INCREASING ALONG THE LINES OF THE 12 AND 18Z GFS FORECASTS FROM EARLIER. WINDS NEAR THE BEACHES WILL AVERAGE 10 KNOTS WHILE 15-18 KNOTS WILL BE MORE COMMON AT DISTANCES GREATER THAN 15 MILES FROM SHORE...ESPECIALLY ACROSS THE NC WATERS. SEAS AT THE CORMP NEARSHORE WRIGHTSVILLE BEACH BUOY HAVE BUILT TO 4 FT...WITH 5 FT NOW BEING REPORTED AT THE FRYING PAN SHOALS BUOY OFFSHORE. A SOLID 4 FT IS EXPECTED FOR MOST AREAS...WITH SOME 5-FOOTERS POSSIBLE OUT NEAR 20 MILES FROM SHORE. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 PM THURSDAY...WINDS FRI WILL BE FROM THE SSW...VEERING TO SW FRI NIGHT INTO SAT NIGHT AND THEN BECOMING LIGHT AND VARIABLE OR EVEN FOR A TIME SHIFTING TO A NORTHERLY DIRECTION LATE SAT NIGHT AND SUN MORNING. STRONGEST WINDS THIS PERIOD WILL OCCUR FRI AFTERNOON INTO SAT AFTERNOON COINCIDENT WITH TIGHTEST PRESSURE GRADIENT AHEAD OF UPSTREAM TROUGH. PRESSURE GRADIENT WILL THEN RELAX GIVEN THE PROXIMITY OF TROUGH SAT NIGHT. THE WAVE SPECTRUM WILL BE DOMINATED BY WIND WAVES FOR MOST OF THE PERIOD...HOWEVER A SE SWELL WILL BE PRESENT. WE WILL BE CLOSE TO SMALL CRAFT ADVISORY CONDITIONS FRI AND FRI NIGHT AS SEAS BUILD. WILL CAP SEAS AT 5 FT WITHIN 20 NM...ALTHOUGH 6 FT SEAS ARE FORECAST JUST BEYOND 20 NM. HIGHEST WINDS WILL BE IN 15 TO 20 KT RANGE...ALTHOUGH SOME GUSTS NEAR 25 KT ARE POSSIBLE LATER FRI AND FRI NIGHT. AT THIS TIME...IT APPEARS CONDITIONS WILL REACH SMALL CRAFT SHOULD EXERCISE CAUTION LEVELS...BUT FALL JUST SHORT OF SMALL CRAFT ADVISORY LEVELS. LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 3 PM THURSDAY...A WEAK SURFACE TROUGH JUST WEST OF THE COASTAL WATERS PAIRED WITH A SPRAWLING HIGH IN THE WEST ATLANTIC WILL BRING A SOUTHERLY COMPONENT TO THE WIND FLOW REGIME. THE PRESENCE OF THE TROUGH WILL PUSH THE BEST GRADIENT OUT TO SEA AND WIND WILL REMAIN QUITE LIGHT. BY MONDAY THIS BOUNDARY WILL WASH OUT LEAVING A MORE TYPICAL SOUTHWESTERLY GRADIENT WIND INDUCED BY THE STALWART BERMUDA HIGH. THE DEVELOPMENT OF A PIEDMONT TROUGH ON TUESDAY INCREASE THE WIND SPEED BY JUST A FEW KNOTS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$