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 290803 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 403 AM EDT TUE JUL 29 2014 .SYNOPSIS... DRIER AND COOLER AIR WILL SETTLE INTO THE REGION IN WAKE OF AN UNUSUALLY STRONG COLD FRONT AS CANADIAN HIGH PRESSURE DROPS INTO THE REGION. RAIN CHANCES WILL RETURN BY NEXT WEEKEND AS HIGH PRESSURE OFFSHORE BUILDS WEST AND BRINGS A RETURN OF MOISTURE TO THE EAST COAST. && .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
AS OF 300 AM TUESDAY...STORY FOR THE NEAR TERM WILL BE THE INFLUX OF LOWER TEMPS/DEWPOINTS AND RESULTANT HUMIDITY LEVELS. A NEARLY FULL LATITUDE UPPER TROF TO AFFECT THE US...MAINLY EAST OF THE MISSISSIPPI RIVER DURING THIS NEAR TERM PERIOD. THIS UPPER TROF AXIS EXTENDS FROM HUDSON BAY OF CANADA SOUTHWARD TO FLORIDA. THIS UNUSUAL WX PATTERN ALOFT IS REMINISCENT OF WHAT USUALLY OCCURS DURING THE WINTER SEASON...NOT THE SUMMER SEASON. VARIOUS MODELS INDICATE 5H TEMPS TO DROP TO AROUND -10...AND 8H TEMPS TO AROUND +10. VARIOUS MODEL TIME HEIGHT DISPLAYS AND SOUNDINGS INDICATE A DRY ATM ABOVE 7H...WITH A SHALLOW DEPTH OF MOISTURE IN THE LOW LEVELS BASICALLY TRAPPED BELOW 7H. WITH THE DAYS HEATING TODAY...WILL LIKELY OBSERVE SCATTERED TO BROKEN SC/CU/AC WITH BASES BETWEEN 4K AND 12K FEET. MODELS INDICATE SOME CHANNELED 5H VORTICITY TO MOVE ACROSS THE FA LATER THIS AFTERNOON AND EVENING DURING THE TIME WHEN THE UPPER TROF AXIS IS NEARLY OVERHEAD. WILL CONTINUE WITH LOW AND MID LEVEL CLOUDS INTO TONIGHT. IF ENOUGH FORCING BECOMES AVBL...WOULD NOT BE SURPRISED TO OBSERVE LOW CLOUD-TOPPED SHOWERS WITH LITTLE IN THE WAY OF ACCUMULATION. WILL STAY CLOSER TO THE NAM MODEL MOS GUIDANCE FOR MAX/MIN TEMPS...ESPECIALLY WHEN DEALING WITH TODAYS MAXES SINCE ITS NEARLY A CATEGORY LOWER THAN THE GFS MOS GUIDANCE.
-- End Changed Discussion --
&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...DEEP DRY AIR WILL REMAIN IN PLACE FOR MUCH OF THE PERIOD AS FLAT MID LEVEL TROUGH JUST WEST OF THE AREA MAINTAINS WESTERLY FLOW ALOFT. SURFACE HIGH NORTHWEST OF THE AREA WED WILL SLIDE EAST ACROSS THE SOUTHERN MID ATLANTIC STATES THU. GRADIENT WILL REMAIN WEAK WITH LIGHT NORTHEAST FLOW BECOMING EASTERLY. HIGHS CLOSE TO WATER TEMPS WILL PREVENT ANY REAL SEA BREEZE FROM DEVELOPING DESPITE WEAK WIND FIELD. WEAK DOWNWARD MOTION AND PRECIPITABLE WATER VALUES AROUND 1 INCH WOULD SUGGEST MOSTLY SUNNY SKIES WED...THOUGH FILTERED THROUGH INCREASING CIRRUS SHIELD LATER IN THE DAY. HOWEVER...GUIDANCE CONTINUES TO SHOW SOME WEAK CONVERGENCE SHOWERS DEVELOPING IN THE AFTERNOON AS EASTERLY WINDS SETUP. NOT READY TO BUY INTO THESE...ESPECIALLY WITH MOS POP IN THE SINGLE DIGIT RANGE...SO WILL MAINTAIN A DRY FORECAST. DESPITE PLENTY OF SUN MID LEVEL TROUGHING KEEPS HIGHS BELOW CLIMO...MID 80S. LOWS BELOW CLIMO ARE EXPECTED WED NIGHT...MID 60S AWAY FROM THE COAST WITH MID TO UPPER 60S ALONG THE COAST. SHORTWAVE DROPPING SOUTHEAST ACROSS THE PLAINS WED INTO THU WILL CAUSE THE 5H TROUGH TO DIG DURING THU. SOUTHWEST FLOW DEVELOPS AS A RESULT COMMENCING A SLOW BUT STEADY INCREASE IN DEEP MOISTURE. THIS WILL LIKELY BE TOO LITTLE TOO LATE AS FAR AS MEASURABLE PRECIP IS CONCERNED FOR THU...BUT THERE WILL BE POTENTIAL FOR AN ISOLATED SHOWER ACROSS SC COUNTIES LATE THU NIGHT. CLOUD COVER WILL INCREASE DURING THE DAY THU WITH SKIES ULTIMATELY BECOMING MOSTLY CLOUD THU NIGHT. COMBINATION OF CLOUD COVER AND INCREASED DEEP MOISTURE WILL KEEP LOWS A BIT WARMER. MOST AREAS ARE LIKELY TO REMAIN BELOW CLIMO BUT ONLY BY A FEW DEGREES. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM TUESDAY...DIGGING MID LEVEL TROUGH AND EXPANDING WESTERN ATLANTIC 5H RIDGE WILL RESULT IN DEEP SOUTHWEST FLOW OVER THE SOUTHEAST THROUGH THE PERIOD. ABUNDANT DEEP MOISTURE AND PERIODIC SHORTWAVE ROUNDING THE BASE OF THE TROUGH WILL KEEP THE WEATHER UNSETTLED THROUGH INTO NEXT WEEK. DIURNAL SHOWERS AND THUNDERSTORMS ARE EXPECTED EACH DAY BUT THERE WILL ALSO BE THE REMAINS OF A SURFACE BOUNDARY STALLED OFF THE SOUTHEAST COAST WHICH WILL MOVE ONSHORE AT SOME POINT OVER THE WEEKEND. MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST POSSIBILITY OF WEAK SUB TROPICAL DEVELOPMENT ALONG THIS BOUNDARY AT SOME POINT...BUT WITH EACH SUBSEQUENT MODEL RUN THE FEATURE BECOMES WEAKER/MORE DIFFUSE. NOT READY TO COUNT ON IT YET BUT DO THINK THE PRESENCE OF THE FRONT WILL INCREASE COVERAGE SAT/SUN. WILL BUMP WEEKEND POP TO HIGH CHC WHILE MAINTAINING LOW/MID CHC POP FRI/MON. CLOUD COVER AND [PRECIP ALONG WITH MID LEVEL TROUGHING WILL KEEP HIGHS BELOW CLIMO THROUGH THE PERIOD. LOWS WILL RUN NEAR TO ABOVE CLIMO AIDED BY CLOUD COVER. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... AS OF 06Z...FRONT HAS DROPPED ACROSS MUCH OF THE REGION WITH THE STRONG CONVECTION NOW WELL OFFSHORE. EXPECT CONVECTIVE DEBRIS CLOUDS TO DISSIPATE AS THEY MOVE OFF THE COAST EARLY ON. LOOKING AT FAIR WEATHER SC/CU DURING THE DAY TUE...AS COOLER AND DRIER AIR CONTINUE TO PUMP ACROSS THE REGION UNDER NW-NE FLOW. THE COASTAL TERMS MAY VEER TO THE E BRIEFLY THIS AFTN. SPEEDS AT 5 TO 15 KT...DROPPING TO LESS THAN 5 KT AFTER SUNSET TUE. OVERALL... LOOKING AT VFR CONDITIONS THRUOUT THE 06Z ISSUANCE PERIOD. EXTENDED OUTLOOK...MVFR DUE TO MORNING FOG POSSIBLE THURSDAY AND FRIDAY. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 8:30 PM MONDAY...VERY STRONG THUNDERSTORMS MOVING ACROSS AMZ 254 AT THIS TIME...BUT THEY WILL CLEAR THE WATERS TO THE EAST WITHIN THE HOURS. UPDATING THE FORECAST ACCORDINGLY. NO OTHER CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: EXERCISE CAUTION CONDITIONS IN EFFECT THROUGH MID EVENING FOR 15-20 KT SW WINDS AND 3-5 FT SEAS. AS A COLD FRONT NEARS THE COAST...THE WINDS WILL DECREASE OVERALL BUT THE TSTM THREAT WILL INCREASE OVER THE WATERS. MARINERS ARE URGED TO GET A FIX ON RADAR EVEN IF HEADING OUT ON THE ICW. SEAS A MIX OF S WAVES 3-4 FT AT 5-6 SECONDS AND SE WAVES 1-2 FT AT 8-9 SECONDS. SEAS WILL LESSEN TO 2-4 FT AND A WINDSHIFT TO THE NW AT 15 KT LOOKS TO OCCUR PRIOR TO DAYBREAK OVER THE WATERS AS A COLD FRONT MOVES THROUGH. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM TUESDAY...HIGH PRESSURE NORTHWEST OF THE WATERS WILL DRIFT EAST WED INTO THU. GRADIENT WILL REMAIN LIGHT THROUGH THE PERIOD WITH EASTERLY WINDS GENERALLY 10 KT OR LESS. LACK OF SIGNIFICANT TEMP DIFFERENCE BETWEEN LAND/WATER RULES OUT A SEA BREEZE EITHER DAY BUT A LAND BREEZE WILL BE POSSIBLE...ESPECIALLY WED NIGHT WITH LOWS DIPPING INTO THE MID TO UPPER 60S. SEAS WILL RUN 2 TO 3 FT THROUGH THE PERIOD. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM TUESDAY...STALLED FRONT OFFSHORE ON FRI WILL BE PUSHED WEST FRI NIGHT INTO SAT...ACCOMPANIED BY UNSETTLED WEATHER. GRADIENT OVER THE WATERS WILL REMAIN WEAK THROUGH THE PERIOD GIVEN THE PROXIMITY TO THE FRONT...BUT DIRECTION WILL BE DEPENDENT ON LOCATION OF THE BOUNDARY. WINDS WILL GENERALLY HAVE AN EASTERLY COMPONENT BUT COULD RANGE FROM SOUTHEAST TO NORTHEAST AT ANY GIVEN MOMENT INTO SAT BEFORE BECOMING SOUTHEAST AS THE BOUNDARY MOVES ONSHORE. LIGHT WINDS AND CHANGEABLE DIRECTION WILL KEEP SEAS IN THE 2 TO 3 FT RANGE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...III NEAR TERM...DCH SHORT TERM...III LONG TERM...III AVIATION...DCH MARINE...

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