Area Forecast Discussion
Issued by NWS Wilmington, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KILM 181727 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 127 PM EDT MON AUG 18 2014 .SYNOPSIS... A COLD FRONT APPROACHING FROM THE NORTH WILL STALL OVER THE AREA THROUGH MID-WEEK...BRINGING A PERIOD OF UNSETTLED AFTERNOON AND EVENING WEATHER. A BUILDING UPPER RIDGE WILL BRING HOT CONDITIONS MID TO LATE WEEK. THE UPPER RIDGE WILL SHIFT WEST OVER THE WEEKEND AND SHOULD TAKE SOME EDGE OFF THE HEAT...ALONG WITH AN INCREASING CHANCE OF SHOWERS AND STORMS. && .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
AS OF 11 AM MONDAY...AUGUST SUNSHINE ROASTING THE REGION WILL SIGNIFICANTLY BOOST AFTERNOON SURFACE-BASED CAPES. CONVECTIVE MESO-SCALE VORTICIES ARE PRESENTLY PASSING WEST TO EAST ACROSS WESTERN AND CENTRAL NORTH CAROLINA IN THE UPPER LEVELS. THESE FEATURES WILL PASS ACROSS SE NC AND NE SC THIS AFTERNOON AND THROUGH EVENING. HIGH PRECIPITABLE WATER CONTENT...STRONG INSOLATION AND ANTICIPATED SEA BREEZE CONVERGENCE SHOULD TEAM TO SET THE STAGE FOR A CONVECTIVE LY ACTIVE AFTN AND EVENING. THE WIND FLOW IN THE COLUMN LOCALLY WILL SUPPORT A STORM MOTION FROM WEST TO EAST AT 25 TO 30 MPH. THE 25-35 KT FLOW IN THE H8-H4 LAYER COULD SHAPE A FEW CONVECTIVE BOW-SEGMENTS AND CONSEQUENTLY STRONG GUSTS. ALTHOUGH SPC DOES NOT INDICATE A SLIGHT RISK TODAY BELIEVE WITH STRONG HEATING IN THE EARLY GOING AND MODERATE MID LEVEL FLOW...A STORMS COULD APPROACH SEVERE LIMITS. MAXIMUM APPARENT TEMPERATURES OF 100-104 EXPECTED TODAY...AND IT MAY TURN OUT HIGHEST NEAR THE COAST WHERE HIGHER DEWPOINTS RESIDE. DIURNAL COOLING IS EXPECTED TO GRADUALLY WEAKEN STORMS OVERNIGHT. ANOTHER SHORT-WAVE ON A MORE SOUTHERLY ROUTE ACROSS SC MAY BRING ANOTHER ROUND OF STORMS...BUT LIKELY NOT BEFORE DAYBREAK TUESDAY.
-- End Changed Discussion --
&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 300 AM MONDAY...HEAT AND HUMIDITY ANTICIPATED FOR THE SHORT TERM...BUT A WEAK COLD FRONT WILL BRING A GOOD CHANCE FOR THUNDERSTORMS ON TUESDAY. GENERALLY FLAT UPPER FLOW THROUGH TUESDAY MEANS FEATURES WILL MOVE BRISKLY TO THE EAST...AND THUS THE COLD FRONT TRAILING FROM A LOW PRESSURE TO OUR NORTH WILL MOVE INTO THE REGION LATE TUESDAY AND THEN WEAKEN OVER THE AREA ON WEDNESDAY. GUIDANCE HAS GOTTEN STRONGER WITH THIS FRONT IN RECENT RUNS...ENCOURAGED BY A SECONDARY VORT WHICH WILL TRACK NEARLY OVERHEAD THE ILM CWA. FOR THIS REASON WILL BUMP POP TO HIGH CHC CWA-WIDE...STILL HIGHEST NORTH...WITH SOME WIND SHIFT POSSIBLE IN THE NORTHERN ZONES. WHETHER THIS FRONT ACTUALLY CROSSES INTO THE CWA WILL MATTER LITTLE TO THE OVERALL SENSIBLE WEATHER...AS PWATS RISE ABOVE 2 INCHES AHEAD OF IT...AND ONLY MINIMAL AIR MASS CHANGE OCCURS BEHIND IT. EXPECT HIGHS TUESDAY TO SOAR INTO THE LOW 90S AWAY FROM THE BEACHES...WITH MID 90S POSSIBLE IN THE WARMER/SUNNIER LOCATIONS. SHOWERS/STORMS ASSOCIATED WITH THE FRONT WILL WANE AND END BY WEDNESDAY MORNING AS DRIER AIR FILTERS INTO THE MID-LEVELS...BUT LOWS TUESDAY NIGHT WILL STAY WELL INTO THE 70S. DRY W/NW MID-LEVEL FLOW COMBINED WITH BULGING THICKNESSES AS A 500MB RIDGE BEGINS TO BLOOM ACROSS THE AREA WILL PUT A CAP ON CONVECTION CHANCES WEDNESDAY. SINCE TEMPS ARE STILL EXPECTED TO RISE INTO THE 90S...AND DEWPOINT TEMPERATURES WILL REMAIN IN THE 70S...ENOUGH INSTABILITY WILL BE PRESENT FOR TYPICAL SEA BREEZE AND PIEDMONT TROUGH CONVECTION...BUT IN A FAR MORE SCATTERED NATURE THAN TUESDAY. LOWS WED NIGHT WILL AGAIN STAY WELL ABOVE NORMAL...MID 70S MOST PLACES. && .LONG TERM /THURSDAY THROUGH MONDAY/... . AS OF 300 AM MONDAY...HOT TEMPERATURES EXPECTED FOR THE BEGINNING OF THE PERIOD...BUT UNCERTAINTY REMAINS INTO THE WEEKEND AS THE MID-LEVEL PATTERN BECOMES VERY AMPLIFIED. GFS CONTINUES TO BE A FAST OUTLIER OF THE DETERMINISTIC MODELS IN BREAKING DOWN THE MID-LEVEL RIDGE AT THE BEGINNING OF THE PERIOD...WHILE OTHER GUIDANCE AND ENSEMBLES ARE SLOWER AND LESS ROBUST IN TROUGH AMPLIFICATION ACROSS THE EAST. AS NOTED BY PREVIOUS FORECASTER...MOS NUMBERS STILL SHOW HOT TEMPS THURSDAY EVEN ON THE LATEST MEX...SEEMINGLY IN CONTRAST WITH THE GFS ITSELF. FOR THIS REASON WILL LEAN ON THE ECMWF WHICH IS MORE MUTED WITH ITS MID-LEVEL AMPLIFICATION...AND CONTINUE TO SHOW A VERY HOT DAY THURSDAY WITH HEAT INDICES APPROACHING 105 ACROSS THE AREA. THEREAFTER...IT DOES APPEAR THAT A TROUGH WILL BEGIN TO DIG INTO NEW ENGLAND AND DOWN THE EASTERN SEABOARD IN RESPONSE TO UPPER RIDGING STRONGLY BLOSSOMING OVER THE CENTER PART OF THE COUNTRY. BENEATH THIS TROUGH...A BACK DOOR COLD FRONT WILL TRY TO PUSH INTO THE AREA FROM THE NORTHEAST...BRINGING A RETURN TO COOLER AND MORE UNSETTLED CONDITIONS FOR THE WEEKEND. STILL A LOT TO RESOLVE IN TERMS OF TIMING AND STRENGTH OF FEATURES...AND WILL FOLLOW THE INHERITED TREND OF A SLOW PATTERN CHANGE INTO THE WEEKEND WITH TEMPS SLOWLY FALLING TO SEASONABLE VALUES...IF NOT SLIGHTLY BELOW BY THE END OF THE PERIOD. IN ADDITION...A BUILDING RIDGE TO THE WEST WITH A SURFACE FRONT IN THE VICINITY AND NW FLOW ENTRENCHED OVERHEAD IS TYPICALLY A SETUP WHICH SUPPORTS NW FLOW TSTM COMPLEX EVENTS. THIS HAS BEEN HINTED FOR SEVERAL RUNS NOW...AND NOTE THAT GUIDANCE HAS SEVERAL MID-LEVEL IMPULSES CRESTING THE RIDGE AND DIVING OVERHEAD AS THIS TROUGH DROPS INTO THE EAST. CANNOT SAY WITH ANY CERTAINTY THAT A NW FLOW EVENT WILL OCCUR LOCALLY...BUT THE SETUP AT LEAST SUPPORTS THE POTENTIAL FRI/SAT. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
AS OF 18Z...STILL SOME CONVECTIVE INHIBITION TO OVERCOME THIS AFTERNOON. CAPES APPROACHING 3000 J/KG ALONG THE COAST...HOWEVER LFC`S STILL HOLDING AROUND 2000 METERS AND HIGHER. BELIEVE THE AFTERNOON HEATING WILL FINALLY OVERCOME THE CIN...AND WE WILL SEE SCATTERED CONVECTION FROM MID TO LATE AFTERNOON...DECREASING AROUND 03Z. WITH PRECIPITABLE WATER JUST UNDER TWO INCHES...HEAVY DOWNPOURS ARE EXPECTED WITH A STORM MOTION AROUND 20 KTS. CONVECTIVE DEBRIS CLOUDS OVERNIGHT...WITH SOME LIGHT FOG POSSIBLE. CONTINUED SOUTHWEST FLOW ON TUESDAY WITH MORE SCATTERED CONVECTION IN THE AFTERNOON. EXTENDED OUTLOOK...CHC AFTERNOON/EVENING SHRA/TSRA THROUGH THE PERIOD. SUB-VFR FOG AND/OR CEILINGS WILL BE POSSIBLE DURING THE EARLY MORNING HOURS EACH DAY.
-- End Changed Discussion --
&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 11 AM MONDAY...WINDS ACROSS THE AREA WATERS WILL REMAIN SW THROUGHOUT THIS PERIOD. LOOK FOR A TIGHTENING SFC PG LATER THIS AFTN AND TONIGHT WHICH WILL YIELD SW WINDS AROUND 15 KT WITH A FEW GUSTS TO 20 KT OVERNIGHT. SIGNIFICANT SEAS THROUGHOUT THIS FORECAST PERIOD WILL BUILD SLOWLY...REACHING 2 TO 4 FT DURING TODAY...3 TO 5 FT TONIGHT. SEAS A FUNCTION OF LOCAL WIND DRIVEN WAVES EXHIBITING 4 TO 6 SECOND WAVE PERIODS. AN EXERCISE CAUTION STATEMENT IS POSSIBLE LATER TODAY OR TONIGHT. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 300 AM MONDAY...LOW PRESSURE MOVING OFF THE MID-ATLANTIC COAST TUESDAY WILL TRAIL A COLD FRONT TOWARDS THE WATERS ON WEDNESDAY. THIS FRONT WILL BE IMPEDED BY HIGH PRESSURE OFFSHORE...AND EXPECT A MINIMAL WIND SHIFT TO THE WEST...IF AT ALL...WEDNESDAY. OTHERWISE...SW WINDS WILL BE 10-15 KTS THROUGH MID-WEEK. SEAS WILL BE FORMED PRIMARILY THROUGH A 5 SEC SW WIND WAVE...ALTHOUGH A WEAK SE GROUND SWELL WILL EXIST DURING THE PERIOD. WAVE HEIGHTS WILL BE 3-4 FT...WITH SOME ISOLATED 5 FTERS ON TUESDAY...FALLING TO 2-3 FT ON WEDNESDAY. LONG TERM /THURSDAY THROUGH FRIDAY/... AS OF 300 AM MONDAY...HIGH PRESSURE OFFSHORE WILL REMAIN THE DOMINANT INFLUENCE THROUGH THE EXTENDED...BUT SOME UNCERTAINTY EXISTS LATE FRIDAY AS A BACK DOOR COLD FRONT APPROACHES. MUCH OF THE LATE-WEEK PERIOD WILL FEATURE S/SW WINDS OF 10-15 KTS...BUT BY LATE FRIDAY A DECREASE IN WIND SPEEDS AND TURN TO THE NORTH IS POSSIBLE...ESPECIALLY ACROSS THE NORTHERN WATERS. SEAS WILL BE 1-3 FT BOTH DAYS...WITH A SE GROUND SWELL AND SOUTHERLY WIND WAVE CREATING THE SPECTRUM. A CONFUSED SEA STATE MAY DEVELOP AT THE VERY END OF THE PERIOD IF THE WINDS TURN TO THE NORTH...BUT ATTM ANY SIGNIFICANT CHANGES TO THE SPECTRUM ARE EXPECTED TO HOLD OFF UNTIL THE WEEKEND. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...COLBY SHORT TERM...JDW LONG TERM...JDW AVIATION...DL/8

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.