Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 242022 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 320 PM EST MON NOV 24 2014 .SYNOPSIS... MILD TEMPERATURES AND UNSETTLED WEATHER IS EXPECTED THROUGH TONIGHT AHEAD OF A COLD FRONT THAT WILL MOVE THROUGH THE AREA OVERNIGHT AND STALL OFFSHORE ON TUESDAY. COOL AND WET CONDITIONS ARE EXPECTED TUESDAY NIGHT AND WEDNESDAY...AS DEEPENING LOW PRESSURE MOVES NORTH ALONG THE STALLED FRONT AND SKIRTS THE COAST. SKIES WILL CLEAR OUT ON THANKSGIVING...WITH TEMPERATURES RUNNING SEVERAL DEGREES BELOW NORMAL INTO THE COMING WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 200 PM MONDAY...WARM AND MOIST AIR WILL CONTINUE TO STREAM INTO THE COASTAL CAROLINAS HELPING TO BRING TEMPS UP INTO THE MID 70S MOST PLACES THIS AFTERNOON. CLOUDS CONTINUED TO COVER THE ENTIRE FORECAST AREA WITH BEST COVERAGE OF SHOWERS THROUGH THE AFTERNOON HOURS LOCATED OVER INLAND AREAS. THERE WAS A VERY SHARP GRADIENT OF CLOUD TO NO CLOUD COVER JUST BEYOND OUR CWA. MOIST SW FLOW WILL CONTINUE THROUGH TONIGHT...BUT DRY AIR THROUGH THE MID LEVELS AND DECENT CAP WITH LAPSE RATES NOT LOOKING TOO GOOD WILL KEEP STRONGER CONVECTION MORE ISOLATED IF AT ALL. LLJ UP TO 45 TO 50 KTS THROUGH THIS EVENING WITH MORE UNIDIRECTIONAL SHEAR OVERALL. EXPECT ONLY A FEW CONVECTIVE CELLS WITH HEAVIER RAIN OR LIGHTNING THROUGH THIS EVE. SOUNDINGS CONTINUE TO DRY OUT THE COLUMN THROUGH THE EVENING HOURS AND EXPECT COVERAGE TO DIMINISH INTO THE EVENING HOURS WITH SHWRS MOVING RAPIDLY OFF TO THE NORTHEAST WITH A SW STORM MOTION UP TO 40S KTS. COLD FRONT WILL PROGRESS THROUGH THE AREA OVERNIGHT. BEST CONVERGENCE WILL ALIGN ITSELF WITH AND JUST AHEAD OF THE FRONT WHICH SHOULD PROGRESS THROUGH THE CWA FROM WEST TO EAST AFTER MIDNIGHT HEADING TOWARD THE COAST BY MORNING. THE BEST UPPER LEVEL SUPPORT WILL ROUND THE BASE OF THE UPPER LEVEL TROUGH REMAINING WELL WEST OF LOCAL AREA BUT MODELS DO SHOW SOME ENHANCED LIFT ALIGNED FROM SW TO NE AS COLD FRONT CROSSES THE AREA AFTER MIDNIGHT. WILL INCREASE COVERAGE AND POPS AT THIS TIME. TEMPS WILL REMAIN WELL ABOVE NORMAL WITH WINDS JUST BEGINNING TO VEER AROUND TO THE WEST BY DAYBREAK IN WESTERN ZONES. DO NOT EXPECT CAA TO AFFECT OVERNIGHT LOWS AND THEREFORE TEMPS WILL REMAIN IN THE 60S FOR MOST OF THE NIGHT WITH READINGS BETWEEN 55 AND 60 MOST PLACES BY DAYBREAK. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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AS OF 3 PM MONDAY...INCREASED CONFIDENCE IN SUBSTANTIAL RAINFALL ESPECIALLY ALONG THE COAST THROUGH THE PERIOD. COLD FRONT PUSHES OFF THE COAST AND DECELERATES EARLY TUESDAY. THE COLD AIR ADVECTION AND DEEP MOISTURE BOTH LAG BEHIND AND THERE SHOULD BE JUST ENOUGH STRUNG OUT VORTICITY AND LOW LEVEL CONVERGENCE FOR OCCASIONAL LIGHT RAIN THROUGH THE DAY. TEMPS WILL BE FAIRLY CLOSE TO CLIMO DESPITE THE WIDESPREAD CLOUDS AND RAINFALL. SEVERAL INGREDIENTS THEN COME TOGETHER TUESDAY NIGHT FOR SOME RATHER IMPRESSIVE DYNAMICS AND POTENTIAL HEAVY RAIN. MID LEVEL IMPULSE CURRENTLY OVER SRN TX SWINGS THROUGH THE TROUGH AND GIVES IT A WEAK NEGATIVE TILT. SURFACE LOW DEVELOPS ALONG THE FRONT OFFSHORE. STRONG SSWRLY LOW LEVEL JET DEVELOPS IN ASSOC WITH THIS WAVE WHILE WEAK ISALLOBARIC COMPONENT TURNS FLOW INTO THE LOW WEST OF IT...I.E. OVER LANDMASS. THIS RESULTS IN AN IMPRESSIVE THERMAL GRADIENT...850MB TEMPS NEAR 15C JUST OFF COAST AND DOWN TO 2 C OVER WRN ZONES BY 12Z WED. THE RESULTING LOW LEVEL FRONTOGENESIS IS SOME OF THE STRONGEST I`VE SEEN IN A WHILE...WITH THE GFS FORECASTING VALUES OF 100-200 UNITS. IT IS ALSO TOUGH TO RULE OUT A NARROW ZONE OF CONDITIONAL SYMMETRIC INSTABILITY DEVELOPING RIGHT OVER THE IMMEDIATE (MAINLY NC) COAST AND ADJACENT WATERS. DURING THE OVERNIGHT HOURS THIS LOW LEVEL FORCING MAY EVEN COUPLE WITH DEEPER ASCENT FROM THE DEVELOPING UPPER JET CONFIGURATION AS THE RIGHT ENTRANCE OF A 190KT UPPER JET MOVES INTO PA. IN FACT GFS CROSS SECTIONS FOR A TIME SHOW ASCENT CLEAR THROUGH THE DEPTH OF THE COLUMN. WITH AT LEAST SOME CONNECTION TO GOMEX MOISTURE THIS SETUP COULD EASILY YIELD 2-2.5 INCHES OF RAINFALL ALONG THE IMMEDIATE COAST BEFORE THE RAIN TAPERS OFF MIDDAY WEDNESDAY OR WEDNESDAY AFTERNOON. THE BULK OF THE RAIN WILL FALL OVERNIGHT TUESDAY TO PERHAPS AS LATE AS DAYBREAK WED. THEREAFTER THE DEEP MOISTURE AND UPPER FORCING SHIFT OFFSHORE. LIGHTER RAIN WED MORNING THEN GIVES WAY TO A DRYING TREND AS COLD AIR ADVECTION BEGINS CRANKING UP BY 18Z. WEDNESDAY AFTERNOON HIGHS WILL NOT BE MUCH HIGHER THAN TUESDAY NIGHT LOWS.
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&& .LONG TERM /THURSDAY THROUGH MONDAY/...
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AS OF 3 PM MONDAY...MID LEVEL TROUGHING OVER THE SOUTHEAST AT THE START OF THE PERIOD WILL LIFT NORTHEAST FRI WITH PROGRESSIVE FLOW DEVELOPING FOR THE WEEKEND. MID LEVEL TROUGH HELPS PUSH REMAINS OF DRY COLD FRONT THROUGH EARLY FRI WITH HIGH PRESSURE BUILDING IN FOR THE WEEKEND. PROGRESSIVE FLOW QUICKLY PUSHES THE CENTER OF THE HIGH OFFSHORE WITH RETURN FLOW DEVELOPING AS EARLY AS MIDDAY SAT. DEEP DRY WESTERLY FLOW WILL HELP KEEP THE REGION DRY THROUGH THE END OF THE PERIOD. TEMPERATURES BELOW CLIMO FOR THE FIRST HALF OF THE PERIOD WILL START A STEADY CLIMB BACK TO CLIMO EARLY NEXT WEEK AS HIGH MOVES FARTHER OFF THE COAST AND RETURN FLOW STRENGTHENS. LATE IN THE PERIOD A WEAK BACKDOOR COLD FRONT WILL TRY TO MOVE SOUTH ACROSS THE AREA. LATEST GFS KEEPS THIS FEATURE NORTH WHILE ECMWF PUSHES IT SOUTH. WILL FAVOR THE ECMWF SOLUTION...WHICH IS FAVORED BY WPC...FOR NOW BUT CONFIDENCE IS LOW.
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&& .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 18Z...LOW LEVEL MOISTURE IS EXPECTED TO HANG IN THERE THROUGH THE FORECAST PERIOD AS SOUTHWEST FLOW CONTINUES. CEILINGS MAY ACTUALLY LOWER A BIT THROUGHOUT THE DAY...WITH ANOTHER ROUND OF LIFR FOG/STRATUS POSSIBLE TONIGHT. BAND OF SHOWERS INLAND EXPECTED TO REMAIN NEARLY STATIONARY...DISSIPATING A BIT THROUGH THIS EVENING. CONTINUED SOUTHWESTERLY FLOW TONIGHT. MOISTURE WILL BE ON THE INCREASE WITH MORE WIDESPREAD SHWRS AFTER MIDNIGHT AS COLD FRONT TRAVERSES THE AREA REACHING CLOSE TO THE COAST BY MORNING. WILL SEE A WIND SHIFT TO THE WEST REACHING LBT AND FLO JUST AROUND 12Z AND THE COASTAL SITES BY LATE MORNING. EXTENDED OUTLOOK...UNSETTLED WEATHER IS EXPECTED THROUGH WEDNESDAY NEAR THE COAST...WITH OCCASIONAL SHOWERS AND MVFR/IFR CONDITIONS. BECOMING VFR WEDNESDAY NIGHT...THROUGH FRIDAY. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 200 PM MONDAY...SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH TONIGHT. GRADIENT WILL RELAX THROUGH TONIGHT WITH WINDS DIMINISHING AS COLD FRONT PROGRESSES EAST REACHING CLOSE TO THE COAST BY DAYBREAK TUES MORNING. MODERATE S-SW FLOW WILL KEEP SEAS ELEVATED IN THE 4 TO 8 FT RANGE THROUGH EARLY THIS EVENING...BUT AS WINDS DIMINISH THROUGH THE NIGHT...SEAS WILL BEGIN TO SUBSIDE. WNA SHOWS WINDS DIMINISHING TO LESS THAN 15 KTS AS THEY BEGIN TO SLOWLY VEER AROUND AS FRONT APPROACHES THE COAST HEADING INTO TUES MORNING. THIS WILL ALLOW SEAS TO SLOWLY SUBSIDE DOWN TO 4 TO 6 FT BY MORNING. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...COLD FRONT PUSHES THROUGH EARLY TUESDAY WITH LITTLE FANFARE OTHER THAN A WIND SHIFT BUT A VERY DYNAMIC SETUP ALOFT WILL LEAD TO A RAPID DECAY IN CONDITIONS TUESDAY NIGHT. LIGHT OFFSHORE WINDS MUCH OF THE DAY TUESDAY AS THE FRONT SLOWS. STRONG SYSTEM SWINGING OUT OF SOUTHERN TEXAS TO THEN CAUSE FAIRLY RAPID PRESSURE FALLS ALONG THE BOUNDARY TUESDAY NIGHT INTO WEDNESDAY. AS THIS LOW CRANKS UP AND MOVES BY CONDITIONS SHOULD RAMP UP TO SMALL CRAFT ADVISORY LEVELS. BY WEDNESDAY MORNING THE STILL DEEPENING LOW ACCELERATES OFF TO OUR NORTH AND EAST. STRONG OFFSHORE WINDS STILL LIKELY WORTHY OF AN ADVISORY LIKELY CONTINUE IN THE ENSUING COLD SURGE AND SEAS WILL SIMILARLY BE HESITANT TO FALL BELOW CRITERIA BEFORE WEDNESDAY NIGHT. LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 3 PM MONDAY...PINCHED GRADIENT THU INTO FRI WILL MAINTAIN OFFSHORE FLOW IN THE 15 TO 20 KT RANGE INTO FRI. GRADIENT WEAKENS MIDDAY FRI FOLLOWING PASSAGE OF REMAINS OF DRY COLD FRONT. NORTH TO NORTHWEST FLOW ON FRI WILL WEAKEN AS SURFACE HIGH BUILDS INTO THE REGION...MOVING OVERHEAD LATE IN THE DAY. WINDS WILL BECOME LIGHT AND VARIABLE LATER FRI AND SAT AS THE SURFACE RIDGE AXIS LINGERS IN THE REGION. SEAS 2 TO 4 FT THU INTO FRI WILL DROP TO 2 FT OR LESS AS WINDS BECOME LIGHT AND VARIABLE.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST TUESDAY FOR AMZ250-252-254- 256. && $$ NEAR TERM...RGZ SHORT TERM...MBB LONG TERM...III AVIATION...DL

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