Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 260512 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 110 AM EDT SAT JUL 26 2014 .SYNOPSIS... A STALLED FRONT ACROSS NORTHEAST SOUTH CAROLINA WILL LIFT NORTH AND DISSIPATE OVERNIGHT INTO SATURDAY. BUILDING HIGH PRESSURE WILL FOLLOW...BRINGING HOT AND HUMID CONDITIONS OVER THE WEEKEND AND MONDAY. ANOTHER UNUSUALLY STRONG COLD FRONT MAY BRING STRONG THUNDERSTORMS LATE MONDAY...FOLLOWED BY COOLER AND DRIER WEATHER TUESDAY...POSSIBLY THROUGH MUCH OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 10:30 PM FRIDAY...A FEW SHOWERS HAVE DRIFTED INTO WILLIAMSBURG COUNTY...OTHERWISE ALL IS QUIET. NO CHANGES NEEDED TO THE FORECAST AS CURRENT SLIGHT CHANCE FOR OUR SOUTHERN COUNTIES WILL COVER SPOTTY SHOWER ACTIVITY FOR THIS EVENING. RELEVANT PORTION OF PREVIOUS DISCUSSION FOLLOWS: MODELS STRUGGLED INITIALLY WITH THE EXCEPTIONAL SOUTHWARD MOVEMENT OF THE COLD FRONT EARLIER THIS MORNING...AND ARE NOW STRUGGLING WITH THE FRONT`S SLUGGISH RETURN NORTHWARD. THE 12Z NAM HAD VERY POOR INITIALIZATION WITH THIS BOUNDARY. THE 12Z GFS WAS INITIALIZED A LITTLE BETTER BUT I AM ESSENTIALLY USING THE RUC...HRRR...AND 12Z WRF-ARW AND WRF-NM MODELS FOR WIND DIRECTION FORECASTS TONIGHT. AS SYNOPTIC HIGH PRESSURE MOVES EAST OFF THE MID-ATLANTIC COAST THIS SHOULD INDUCE THE FRONT TO RETURN NORTHWARD...ALBEIT MORE SLOWLY THAN MOST SYNOPTIC GUIDANCE IS INDICATING. WITH RICH LOW-LEVEL MOISTURE AND RELATIVELY DRY AIR IN THE MID-LEVELS...CALM WINDS...AND SLOWLY CLEARING SKIES...IT IS A GOOD SETUP FOR FOG OR LOW STRATUS OVERNIGHT. VISIBILITIES WILL PROBABLY BEGIN DECREASING AFTER MIDNIGHT WITH THE WORST CONDITIONS AROUND DAYBREAK. LOWS SHOULD REACH THE LOWER 70S WITH SOME MID 70S NEAR THE COAST. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 315 PM FRIDAY...MAIN WEEKEND WEATHER HEADLINE IS EXPANDING HEAT AND HUMIDITY. HEAT INDICES/APPARENT TEMPERATURES FACTORING IN ELEVATED DEWPOINT VALUES...YIELDS 97-102 DEGREE INDICES FOR SATURDAY...AND INTO THE BROILER SUNDAY AS MAXIMUM APPARENT TEMPS SUNDAY AFTERNOON CREST TO 104-107 DEGREES. IF CONSISTENCY HOLDS IN THE MAX TEMP FORECAST...THEN WE WILL BE LOOKING AT PROSPECTS OF A HEAT ADVISORY NEEDED ON SUNDAY. PCPN-WISE...BEST CHANCE LOOKS TO BE SATURDAY AS A DECAYING FRONTAL BOUNDARY LIFTS NORTH ACROSS CAPE FEAR AND SE NC. DRY MID-LEVEL AIR WILL PLACE LIMITATIONS OF PCPN EXTENT AND MAGNITUDE SATURDAY...BUT A FEW SHOWERS SHOULD BE EXPECTED ON SATURDAY AS LOW-LEVEL MOISTURE LINGERS. SUNDAY LOOKS DRYISH WITH WESTERLY FLOW THROUGH MUCH OF THE COLUMN SQUELCHING RAIN CHANCES. BECAUSE OF INTENSE HEAT AT THE SURFACE SUNDAY HOWEVER...AN ISOLATED TSTM CANNOT BE RULED ENTIRELY. DUE TO THE GRADUAL BUILD UP OF HEAT...VERY MILD MINIMUMS SUNDAY AND MONDAY DAYBREAK ARE ANTICIPATED...ESSENTIALLY MIDDLE 70S TO THE LOWER 80S AND MILDEST NEAR THE SEA...PARTICULARLY AS WE SEE STILL SW WINDS HOLDING UP IN THE OVERNIGHT PERIODS...ESPECIALLY LATE SUNDAY INTO EARLY MONDAY. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 315 PM FRIDAY...IMPRESSIVE MID-LEVEL AMPLIFICATION THROUGH THE EXTENDED WILL DRIVE ACTIVE WEATHER THE FIRST PORTION OF THE EXTENDED...BUT QUIET AND COOL CONDITIONS WILL FOLLOW THE MAJORITY OF THE UPCOMING WEEK. MONDAY SHAPING UP TO BE ONE OF THE HOTTEST DAYS OF THE YEAR LOCALLY...AS RETURN FLOW STRENGTH INCREASES...AND 850MB TEMPS CLIMB ABOVE 20C. COMBINE THIS WITH WHAT WILL LIKELY BE A VERY WARM START TO THE DAY (WARM OVERNIGHT LOWS FROM SUNDAY)...AND MONDAY WILL FEATURE WIDESPREAD MID 90S ACROSS THE AREA...WITH UPPER 90S POSSIBLE IN MANY SPOTS. THESE TEMPS COMBINED WITH HIGH DEWPOINTS WILL BRING APPARENT TEMPS TO NEAR HEAT ADVISORY CRITERIA ON MONDAY. THIS WILL BE THE LAST SUMMER-LIKE DAY FOR QUITE SOME TIME THOUGH...AS AN ANOMALOUSLY SHARP TROUGH (UP TO -4 SD) DIVES INTO THE EASTERN CONUS. BENEATH THIS TROUGH A STRONG COLD FRONT WILL CROSS THE LOCAL AREA MONDAY EVE AND NIGHT...MOVING OFFSHORE BY TUESDAY MORNING. A STRONG COLD FRONT DIVING INTO A VERY WARM UNSTABLE AIRMASS WILL SUPPORT THE CHANCE FOR STRONG CONVECTION ON MONDAY...AND SPC IS ALREADY HIGHLIGHTING THE REGION IN THE D4 OUTLOOK. IT IS TOO EARLY TO FOCUS ON DETAILS OF COURSE...BUT A STRONG COLD FRONT IMPINGING ON A HIGHLY UNSTABLE AIRMASS WITH RAPID HEIGHT FALLS AND STRONG MID-LEVEL FLOW IS UNQUESTIONABLY A SOLUTION WHICH SUPPORTS CONVECTION. WILL BUMP TO LIKELY POP MONDAY FOR MUCH OF THE AREA. TO USE THE WORD SIGNIFICANT TO DESCRIBE THE AIR MASS CHANGE FROM MONDAY THROUGH WEDNESDAY MAY BE AN UNDERSTATEMENT...AS 850MB TEMPS DROP FROM AROUND 21C (+2 SD) TO 13C (-2 SD) IN JUST 48 HOURS! WHILE THIS OCCURS...PWATS DROP BELOW 1 INCH BY WEDNESDAY AS WELL...AND THUS THE TUE/WED/THU TIMEFRAME SHOULD BE DRY LOCALLY...ALBEIT WITH TEMPS WELL BELOW NORMAL FOR LATE JULY. ALTHOUGH STRONG CAA EVENTS IN JULY ARE...NOT SURPRISINGLY...RARE...EXPECT GUIDANCE IS OVERDOING TEMP FORECASTS MID WEEK AND WILL UNDERCUT NUMBERS...WITH TEMPS LIKELY 5-10 DEGREES BELOW NORMAL MUCH OF NEXT WEEK. LATE IN THE WEEK...MID-LEVEL TROUGH BEGINS TO WEAKEN...AND STRONG RIDGE OVER THE ATLANTIC BEGINS TO PUSH BACK TO THE WEST DRIVING A RETROGRADING PATTERN INTO FRIDAY...DRIVING WARMING TEMPS BUT INCREASING CHANCES FOR POP. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
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AS OF 06Z...FEW LEFTOVER CONVECTIVE DEBRIS CLOUDS OTHERWISE RADIATIONAL COOLING WILL RULE THE AM HOURS. RESIDUAL LOW LEVEL MOISTURE WILL RESULT IN LOW STRATUS CLOUD DECKS...MAINLY AFFECTING THE INLAND TERMINALS. FOG WILL ALSO BECOME A HINDRANCE TO AVIATORS WITH GUIDANCE POINTING TOWARDS DENSE FOG ESPECIALLY ACROSS THE INLAND TERMS. BY 12Z AND AFTER A COUPLE HOURS OF INSOLATION...THE FOG SHOULD QUICKLY DISSIPATE. FOR SATURDAY MIDDAY THROUGH EARLY EVENING...2 SFC BASED FEATURES...SEA BREEZE AND THE PIEDMONT TROF... WILL BE THE DRIVING FORCE FOR POSSIBLE ISOLATED CONVECTION. HOWEVER...PROGGED SUBSIDENCE ALOFT WILL KEEP THUNDERSTORM ACTIVITY LIMITED IN AREAL COVERAGE AND IN STRENGTH. EXTENDED OUTLOOK...SHOWERS/TSTMS/TEMPO MVFR POSSIBLE SUNDAY AND MONDAY. OTHERWISE EXPECT VFR.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 10:30 PM FRIDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: ISOLATED SHOWERS POSSIBLE AFTER MIDNIGHT OVER THE OUTER FRINGES OF THE WATERS...BUT ANY MORE SUBSTANTIAL THUNDERSTORM ACTIVITY IS UNLIKELY. A COLD FRONT SHOULD BEGIN TO MOVE NORTHWARD OVERNIGHT...REACHING CAPE FEAR LATER THIS EVENING AND EVENTUALLY MOVING NORTHWARD INTO EASTERN NORTH CAROLINA. WINDS WILL TURN SOUTHERLY OVERNIGHT...BUT WITH LITTLE INCREASE IN WIND SPEED EXPECTED FROM PRESENT 10 KT RANGE. SEAS CURRENTLY 2-3 FEET ARE EVENLY SPLIT BETWEEN A 9-SECOND SOUTHEAST SWELL AND SHORTER PERIOD WAVES PRODUCED BY LOCAL WINDS. LITTLE CHANGE IS ANTICIPATED OVERNIGHT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 315 PM FRIDAY...THE MARINE WEEKEND HEADLINE...INCREASING SW WINDS SATURDAY THROUGH SUNDAY...WITH AN EXERCISE CAUTION MARINE CONDITIONS LIKELY DEVELOPING SUNDAY OR SUNDAY NIGHT...FOR 15-20 KT SW WINDS AND SEAS OF 4-5 FEET. THEREFOR WHILE SATURDAY WILL BE A MANAGEABLE DAY FOR BOATING...SUNDAY WILL BECOME BUMPY AND A BIT MORE HAZARDOUS AS WIND-WAVES CONTINUE TO GROW IN PERSISTENT AND MODERATELY STRONG SW WINDS. ISOLATED TSTMS EXPECTED ON THE WATERS EARLY SATURDAY...AND POTENTIALLY LATE SUNDAY NIGHT OFFSHORE. .LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 3 PM THURSDAY...STRONG PRE-FRONTAL FLOW AHEAD OF A COLD FRONT WILL PUSH WINDS UP ABOVE 20 KTS FROM THE SW ON MONDAY...DRIVING SEAS TO 4-6 FT...AND A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED ON MONDAY. THIS FRONT WILL CROSS THE WATERS MONDAY NIGHT...WITH A RAPID WIND SHIFT TO THE NW BY TUESDAY MORNING...AND SPEEDS EASING THROUGH TUESDAY TO 5-10 KTS. WEAK AREA OF HIGH PRESSURE WILL BUILD ACROSS THE WATERS THEREAFTER...CAUSING WINDS TO BECOME NE AROUND 10 KTS. AFTER THE SCA CONDITIONS SUBSIDE MONDAY NIGHT...SEAS WILL BE 2-4 FT THROUGH THE REMAINDER OF THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...MJC NEAR TERM...REK/TRA SHORT TERM...MJC LONG TERM...JDW AVIATION...DCH

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