Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 021919 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 319 PM EDT SUN AUG 2 2015 .SYNOPSIS... LOW PRESSURE WILL MOVE NORTHEASTWARD ACROSS THE FLORIDA PANHANDLE TONIGHT AND ALONG AN OLD STATIONARY FRONT MONDAY AND TUESDAY... BRINGING INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS TO THE COASTAL CAROLINAS. THE LOW WILL MOVE AWAY FROM THE AREA TUESDAY NIGHT...WITH TYPICAL SUMMER WEATHER EXPECTED WEDNESDAY THROUGH NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... AS OF 300 PM SUNDAY...CONVECTION IS FILLING IN ALONG THE SEA BREEZE BOUNDARY AND THE DRYLINE FEATURE JUST INLAND. I HAVE INCREASED POPS FOR THE NEXT FEW HOURS TO ADDRESS. THIS ACTIVITY IS SPITTING OUT BOUNDARIES AND AN INTERESTING BOUNDARY IS APPROACHING THE COAST FROM CONVECTION ACROSS THE GULF STREAM SO ACTIVITY COULD LAST A WHILE. BOTH THE GFS AND NAM SHOW LOW LEVEL WIND FIELDS BACKING WITH HEIGHT THUS INCREASING CONVERGENCE BASICALLY ALONG THE COAST...THIS OCCURS AFTER 0600 UTC. THE GFS HAS BACKED OFF SLIGHTLY WITH THE 1200 RUN WHILE THE NAM REMAINS THE MOST AGGRESSIVE. I AM CONTINUING TO ADVERTISE GOOD CHANCE POPS ALONG THE IMMEDIATE COAST WITH MUCH HIGHER AMOUNTS OFFSHORE. FOLKS WEST OF I-95 WILL PROBABLY MISS OUT ENTIRELY. THE NAM IS ADVERTISING 0.25 TO 0.50 FOR THE SIX HOUR PERIOD WHILE THE GFS JUST UNDER A TENTH. MY EXPERIENCE SHOWS THAT ALTHOUGH MOST AREAS...ALONG THE COAST RECEIVE RAINFALL...THE QPF IS LIGHT AS THE HEAVIER ACTIVITY RESIDES JUST OFFSHORE. THIS IS PROBABLY WHAT WE WILL SEE THROUGH 1200 UTC. I LIKE THE SLIGHTLY WARMER GFS/MAV NUMBERS FOR LOWS WITH ALL OF THE CLOUD COVER MOVING IN. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...THE BIG PLAYER IN THE MONDAY-TUESDAY TIMEFRAME IS THE LOW CENTERED NEAR THE GULF COAST ABOUT 50 MILES SOUTHEAST OF TALLAHASSEE FLORIDA. WHILE MODEL SOLUTIONS ARE ALL OVER THE PLACE WITH REGARD TO TIMING...THE 12Z GFS APPEARS TO HAVE TO HAVE A SUPERIOR FORECAST WITH ITS SLOWER NORTHEASTWARD MOVEMENT ALONG THE OLD STATIONARY FRONT. THE 12Z NAM AND 12Z CANADIAN MODELS IN PARTICULAR ARE FAR TOO FAST AND HAVE BEEN ENTIRELY DISCOUNTED FOR THIS FORECAST. A SURGE OF DEEP TROPICAL MOISTURE AHEAD OF THE LOW WILL REACH THE CAROLINA BEACHES MONDAY MORNING. PRECIPITABLE WATER VALUES WILL EXCEED TWO INCHES ALONG THE COAST...WHILE SOUTHERLY/ONSHORE FLOW SHOULD INCREASE LOW-LEVEL CONVERGENCE ALONG THE STATIONARY FRONT. A SUBTLE 300 MB DISTURBANCE MOVING ACROSS NORTHERN NC AND OFF THE COAST MONDAY MORNING WILL HELP ENHANCE UPPER LEVEL DIVERGENCE ACROSS OUR AREA...AND IT WOULD NOT BE SURPRISING AT ALL TO SEE GOOD COVERAGE OF STORMS ONGOING AT DAYBREAK. HEAVY RAINFALL IS EXPECTED AND THERE IS SOME POTENTIAL OF FLOODING...ESPECIALLY WITHIN 50 MILES OF THE COAST BENEATH THE DEEP MOISTURE CHANNEL. ONSHORE WINDS WILL CONTINUE MONDAY NIGHT INTO TUESDAY AS THE LOW APPROACHES THE AREA. I HAVE HELD OFF INCREASING POPS BEYOND 50 PERCENT FOR EITHER PERIOD NOT KNOWING HOW SYMMETRIC CONVECTION WILL BE DISTRIBUTED AROUND THE LOW...AND TO ACCOUNT FOR MESOSCALE SUBSIDENCE AREAS AROUND LARGE CONVECTIVE STRUCTURES POTENTIALLY DEVELOPING OUT OVER THE GULF STREAM. TUESDAY NIGHT THE LOW SHOULD BE MOVING NORTHEAST OF THE AREA. DRIER AIR WRAPPING IN BEHIND THE CIRCULATION SHOULD HELP ERODE CLOUDS AND KILL PRECIPITATION CHANCES. EXTRATROPICAL STORM SURGE GUIDANCE SHOWS SURGE VALUES REMAINING UNDER HALF A FOOT AT THE BEACHES...AND WE ARE MOVING PAST THE FULL MOON WHICH SHOULD PREVENT COASTAL FLOODING ISSUES. FARTHER INLAND ALONG AND WEST OF THE INTERSTATE 95 CORRIDOR (WHERE RAIN IS BADLY NEEDED) THE BULK OF THIS EVENT WILL REMAIN TOO FAR EAST. POPS ARE ONLY 10-30 PERCENT AND DAYTIME TEMPERATURES SHOULD RUN 5-8 DEGREES WARMER THAN AT THE COAST. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 3 PM SUNDAY...RAIN CHANCES WILL REMAIN QUITE MINIMAL FOR MOST OF WEDNESDAY BUT LATE IN THE DAY SOME WEAK CYCLONIC CURVATURE MAY IMPINGE UPON US FROM THE WEST. AS THIS CONTINUES INTO THURSDAY WITH THE AID OF DAYTIME HEATING THE RADAR SHOULD LIGHT UP PRETTY NICELY IN THE AFTERNOON EVEN THOUGH THE GFS IS NOT TOO ENAMORED WITH THE IDEA. THE LOWERED HEIGHTS AND ADDED CLOUDS SHOULD TEMPER THE HEAT EVEN IF ONLY BY A FEW DEGREES. FROM THERE RAIN CHANCES SHOULD INCREASE EVEN FURTHER ON FRIDAY AS BOTH A COLD FRONT AND STRONGER ENERGY ALOFT APPROACH FROM POINTS NORTH AND WEST. THERE MAY EVEN BE A HEALTHY WAVE ALONG THE FRONT WHICH COULD LEAD TO QUITE A BIT OF RAIN. THE FRONT WILL BE DECELERATING MAKING FIGURING OUT HOW QUICKLY WE DRY OUT DIFFICULT. WILL JUST SHOW A SLOW DECREASE IN RAIN CHANCES DURING THE LATTER PART OF THE WEEKEND. WE SHOULD ALSO SEE A RETURN OF MORE SEASONABLE DAYTIME HIGHS LATE IN THE PERIOD WHEREAS AREAS AWAY FROM THE WATER MAY FLIRT WITH HEAT ADVISORY CRITERIA WEDNESDAY AND THURSDAY. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 18Z...TERMINALS ARE VFR AND VFR IS LIKELY THROUGH THIS EVENING. SCT LOW/MID CLOUDS EXPECTED. NE-E WINDS WILL BECOME SE...AND ISOLATED SHOWERS WILL DEVELOP ALONG THE SEA BREEZE AS IT MOVES INLAND. THE CHANCE OF VCSH IS LOW AT THE TERMINALS HOWEVER...WITH AN EVEN LESS CHANCE OF VCTS. THIS EVENING WINDS BECOME LIGHT/VARIABLE AT KFLO/KLBT AND LIGHT SW AT THE COASTAL TERMINALS. OVERNIGHT VFR BECOMING MVFR DUE TO BR IN THE PRE-DAWN HOURS AT KFLO/KLBT. SHOWERS WILL BE INCREASING AT THE COASTAL TERMINALS AFTER MIDNIGHT Z AS LOW PRESSURE APPROACHES FROM THE SW. TEMPO MVFR POSSIBLE MAINLY KMYR/KCRE DUE TO REDUCED VSBYS BEFORE 14Z. AFTER 14Z BEST CHANCE OF MVFR WILL BE AT KILM AS LOW PRESSURE MOVES FURTHER NE UP THE COAST. CONFIDENCE OF IFR IS LOW ATTM. EXTENDED OUTLOOK...PREDOMINANTLY VFR THROUGH THE PERIOD WITH A SLIGHT CHANCE AFTERNOON SHRA/TSRA. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 120 PM SUNDAY...THE PRESSURE GRADIENT WILL INCREASE SLIGHTLY THROUGH THE LATER AFTERNOON AND OVERNIGHT HOURS. THE OVERALL PATTERN IS STILL RELATIVELY WEAK HOWEVER (41013 IS CURRENTLY REPORTING CALM WINDS) AND WINDS WILL LOSE THE SEA BREEZE INFLUENCE OF A SE DIRECTION AND GO MORE SOUTHWEST. SPEEDS SHOULD SETTLE NICELY INTO A 10-15 KNOT RANGE. SEAS WILL INCREASE FROM 2-4 FEET TO 3-5 FEET AFTER 0600 UTC VIA THE SUBTLE INCREASE IN WINDS AND A DECENT SWELL COMPONENT REMAINING IN THE MIX. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...A ROUGH COUPLE OF DAYS FOR THE MARINE COMMUNITY IS COMING UP AS LOW PRESSURE CENTERED ABOUT 50 MILES SOUTHEAST OF TALLAHASSEE FLORIDA MOVES ACROSS THE COASTAL CAROLINAS. THE GFS MODEL IS THE BASIS FOR OUR FORECAST...SHOWING A MUCH SLOWER MOVEMENT OF THE LOW THAN THE NAM OR CANADIAN MODELS. SOUTH WINDS WILL INCREASE TO 15-20 KT MONDAY INTO TUESDAY AHEAD OF THE LOW. MULTIPLE WAVES OF SHOWERS AND THUNDERSTORMS WILL MOVE ACROSS THE AREA...ACCOMPANIED BY LOW VISIBILITY IN HEAVY RAIN AND POSSIBLE SQUALLY WIND GUSTS. THE LOW WILL MOVE NORTHEAST OF CAPE FEAR TUESDAY NIGHT...WITH LIGHTER OFFSHORE WINDS DEVELOPING OVERNIGHT. SEAS WILL BUILD TO 4-6 FEET MAINLY IN 6 SECOND SOUTH WAVES PRODUCED BY THE FETCH BEGINNING NEAR JACKSONVILLE FL AND ENDING AT OUR BEACHES. SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 3 PM SUNDAY...BERMUDA HIGH PRESSURE AND WEAK PIEDMONT TROUGHINESS THE MAIN PLAYERS ON WEDNESDAY. SOUTHWESTERLY WINDS A LITTLE ON THE LIGHT SIDE POSSIBLY CAPPED AT 10 KNOTS. THE TROUGH WILL BE STRONGER ON THURSDAY OPENING THE FORECAST UP TO A MORE TYPICAL 10 TO 15 KT AND POSSIBLY DECREASING THE NEARSHORE/OFFSHORE WAVE HEIGHT GRADIENT EVER SO SLIGHTLY. A COLD FRONT WILL BE APPROACHING ON FRIDAY THOUGH ITS SPEED IS A BIT UNCERTAIN ESPECIALLY SINCE IT MAY BE DECELERATING. THERE MAY BE A SLIGHT LATE PERIOD VEERING AND INCREASE IN WIND SPEED. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...COASTAL FLOOD ADVISORY FROM 11 PM THIS EVENING TO 1 AM EDT MONDAY FOR NCZ107. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...SHK SHORT TERM...TRA LONG TERM...MBB AVIATION...MRR

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