Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 211419
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1019 AM EDT SUN SEP 21 2014

.SYNOPSIS...
DEEPENING LOW PRESSURE OFFSHORE WILL MOVE NORTHEAST AWAY FROM THE
AREA THIS MORNING...LEAVING DRY AND WARM CONDITIONS BY THIS
AFTERNOON. A COLD FRONT WILL CROSS THE AREA EARLY MONDAY WITH
ISOLATED SHOWERS AND THUNDERSTORMS. MUCH COOLER AIR WILL FOLLOW
FOR THE MIDDLE OF THE WEEK. A TROUGH WILL SHARPEN OFFSHORE AND
MOVE TOWARDS THE COAST...BRINGING INCREASING RAIN CHANCES FOR THE
LATTER PART OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM SUNDAY...CLEARING LINE AND ASSOCIATED LIGHT
RAIN/DRIZZLE IS JUST ABOUT ON SCHEDULE EXITING TO THE
EAST/NORTHEAST. THE LATEST GUIDANCE SHOWS MAX TEMPERATURES ARE ON
TRACK. NO CHANGES TO THE FORECAST WITH THE MID MORNING UPDATE.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 AM SUNDAY...MONDAY BRINGS THE LAST DAY OF ASTRONOMICAL
SUMMER...AS THE FALL EQUINOX OCCURS AROUND 1030 PM MONDAY NIGHT.
RIGHT ON CUE...A FALL-LIKE COLD FRONT WILL CROSS THE AREA DURING
MONDAY...USHERING IN TRUE FALL-LIKE AIR FOR TUESDAY. BEFORE THE COOL
DRY AIR CAN OVERSPREAD THE CAROLINAS...SHOWERS AND THUNDERSTORMS ARE
EXPECTED ALONG THE COLD FRONT MONDAY AFTN. ALTHOUGH MOIST ADVECTION
AHEAD OF THIS FEATURE IS LIMITED...THE FROPA TEMPORALLY MATCHING
PEAK HEATING SHOULD PROVIDE ENOUGH FORCING FOR SCT
SHOWERS/TSTMS...WITH HIGHEST POP EXPECTED ALONG THE COAST WHERE THE
DEEPER...YET STILL MODERATE...MOISTURE WILL RESIDE. INHERITED
FORECAST HAS SCHC FOR MONDAY...AND WILL MAKE ONLY MINOR UPTICKS
ALONG THE COAST. PRECIP WILL WANE QUICKLY AFTER DARK THANKS TO LOSS
OF HEATING AND THE COLD FRONT MOVING FURTHER AWAY...ALLOWING FOR
RAPID COOL/DRY ADVECTION TO ENGULF THE AREA. THIS WILL LEAVE A
BEAUTIFUL...ALTHOUGH A BIT WINDY...FALL DAY ON TUESDAY AS EXPANSIVE
CANADIAN HIGH PRESSURE RIDGES DOWN FROM THE GREAT LAKES.

ALTHOUGH SUNSHINE WILL BE PLENTIFUL ON TUESDAY...HIGHS WILL STRUGGLE
ON CONTINUED...BUT WEAKENING...CAA...LEAVING HIGHS IN THE UPPER
70S...A FEW DEGREES COOLER THAN THOSE EXPECTED MONDAY. MINS BOTH
NIGHTS WILL DROP TO SOME OF THE COOLEST VALUES WE HAVE SEEN IN A
WHILE...WITH MID/UPR 50S EXPECTED INLAND...AND RIGHT AROUND 60 AT
THE COAST.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 300 AM SUNDAY...STALLED COLD FRONT OFFSHORE WILL TRANSITION
INTO A COASTAL TROUGH...AIDED BY DEVELOPING SHORTWAVE ENERGY
MID-TO-LATE WEEK. THIS WILL COMBINE WITH A STRENGTHENING HIGH
PRESSURE WEDGE JUST INLAND OF THE COAST TO PRODUCE COOL AND
INCREASINGLY UNSETTLED WEATHER DURING THE EXTENDED. ALTHOUGH THERE
IS STILL SOME DISAGREEMENT AMONG THE DETERMINISTIC MODELS ABOUT THE
AMOUNT OF CLOUDS/PRECIP EXPECTED...THEY ARE ALL MORE PESSIMISTIC IN
THEIR SOLUTIONS FOR LATE WEEK.

DEEP EASTERLY FLOW THROUGH AT LEAST HALF THE ATMOSPHERIC COLUMN WILL
ADVECT AMPLE MOISTURE TOWARDS THE CAROLINAS...WHILE AT THE SAME TIME
DRIVING THE COASTAL TROUGH TOWARDS SHORE. THIS COMBINING WITH THE
AFOREMENTIONED VORT ENERGY ALOFT MAY EVEN SPAWN WEAK LOW
PRESSURE...ALL OF WHICH POINT TO DETERIORATING WEATHER CONDITIONS
LOCALLY. COOL E/NE WINDS AT THE SURFACE WITH EASTERLY FLOW TOPPING
THAT WILL CREATE WIDESPREAD LOW-CLOUD COVER AND PERIODS OF
SHOWERS...WITH THE BEST CHANCE ALONG THE COAST LATE IN THE WEEK AS
ISENTROPIC LIFT AMPLIFIES. WITH A STRONG WEDGE IN PLACE AND A
STRENGTHENING COASTAL TROUGH IN THE VICINITY...THE FIRST WEEK OF
FALL LOOKS TO TAKE ON A DECIDEDLY WINTER-LIKE FEEL WITH
CLOUDS...PERIODS OF RAIN...AND TEMPS BELOW CLIMO.

DRYING SHOULD FINALLY BEGIN BY THE WEEKEND AS RIDGING DEVELOPS
ALOFT...SQUELCHING THE COASTAL TROUGH AND ERODING MUCH OF THE MID
AND UPPER LEVEL MOISTURE.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
AS OF 12Z...LOW PRESSURE OFFSHORE IS NOW TRACKING AWAY FROM THE
REGION...TAKING THE DEEP MOISTURE ALONG WITH IT. SOME IFR CEILINGS
REMAIN AT ILM...WITH SOME LINGERING SHOWERS AT THE MYRTLES. VFR
CONDTIONS WILL PREVAIL AT ALL TERMINALS IN A COUPLE OF HOURS. WINDS
ALREADY NORTHWEST AND THIS WILL CONTINUE WITH SOME GUSTINESS
THROUGHOUT THE DAY. DIMINISHING WINDS THIS EVENING AS THEY BACK TO
THE SOUTHWEST.

EXTENDED OUTLOOK...VFR THROUGH WED WITH A CHANCE OF A SHOWER WITH A
COLD FRONT ON MONDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM SUNDAY...SEAS ARE ON THE WAY DOWN THIS MORNING AND
THE SMALL CRAFT ADVISORY SHOULD BE GOOD TO GO (EXPIRE) AT NOON. NO
CHANGES TO THE FORECAST.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 AM SUNDAY...WESTERLY WINDS AROUND 10 KTS WILL START THE
PERIOD...BEFORE A COLD FRONT CROSSES THE WATERS DURING MONDAY AFTN.
THIS WILL CAUSE A WIND SHIFT TO THE NORTH MONDAY EVENING...WITH
FURTHER VEERING TO THE NORTHEAST OCCURRING MONDAY NIGHT. AS THESE
WINDS BECOME FROM THE NE...THEY WILL BE ACCOMPANIED BY A
STRENGTHENING SURGE WITH WIND SPEEDS RISING TO 15-20 KTS. HIGH
PRESSURE RIDGING DOWN THE COAST ON TUESDAY...COMBINED WITH THIS COLD
FRONT STALLING OFFSHORE...WILL KEEP A PINCHED GRADIENT...AND NE
WINDS WILL STEADILY RISE TO 20-25 KTS THROUGHOUT TUESDAY. SEAS
THROUGH THE DAYLIGHT HOURS OF MONDAY WILL BE 2-3 FT WITH A VARIABLE
WIND DIRECTION CAUSING A CONFUSED SPECTRUM. BEGINNING MONDAY NIGHT
HOWEVER...AS THE NE SURGE DEVELOPS AND PERSISTS...SEAS WILL BUILD
FROM 2-3 FT TO 4-6 FT...AND A SMALL CRAFT ADVISORY WILL LIKELY BE
NEEDED BEGINNING TUESDAY NIGHT.

LONG TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 300 AM SUNDAY...HIGH PRESSURE WILL RIDGE DOWN THE COAST
THROUGH THE PERIOD...WHILE A COASTAL TROUGH STRENGTHENS OFFSHORE.
THIS CREATES A PINCHED GRADIENT BOTH WED AND THU...DRIVING
PERSISTENT AND STRONG NE WINDS OF 20-25 KTS INTO LATE WEEK. THESE
WINDS WILL DRIVE SEAS TO 4-7 FT THROUGH THE COASTAL WATERS...WITH
THE EXCEPTION BEING ALONG THE NEAR-SHORE WATERS OF AMZ252 AND AMZ254
WHERE WAVE SHADOWING IS LIKELY AND AMPLITUDES WILL THUS BE LOWER.
EVEN SO...AN EXTENDED SMALL CRAFT ADVISORY IS EXPECTED DURING THIS
PERIOD.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR AMZ250-252-254-
     256.

&&

$$
SYNOPSIS...JDW
NEAR TERM...SHK
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...HDL





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