Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 310710
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
310 AM EDT FRI OCT 31 2014

.SYNOPSIS...
HIGH PRESSURE WILL NUDGE INTO THE AREA TODAY BETWEEN AN
APPROACHING COLD FRONT TO THE WEST AND A WEAK AREA OF LOW PRESSURE
ALONG A STALLED FRONT OFFSHORE. A POWERFUL COLD FRONT WILL CROSS THE
REGION ON SATURDAY AS COLD CANADIAN HIGH PRESSURE BUILDS IN THROUGH
THE REST OF THE WEEKEND. THIS AREA OF HIGH PRESSURE WILL THEN BECOME
THE DOMINANT WEATHER FEATURE THROUGH THE FIRST HALF OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1030 PM THURSDAY...RADAR AND SATELLITE IMAGERY IMPLY THAT
ISENTROPIC LIFT IS INCREASING 20-40 MILES OFF THE SOUTHERN AND
CENTRAL SOUTH CAROLINA COAST. THIS AREA IS MOVING NORTHEAST AND
SHOULD MISS THE POINT OF CAPE FEAR BY A COMFORTABLE MARGIN. HOWEVER
ADDITIONAL ISENTROPIC LIFT DEVELOPING IN THE 06-12Z TIMEFRAME MAY
STILL SPREAD SOME SHOWER ACTIVITY INLAND ALONG THE COAST. BESIDES
ADJUSTING FORECAST TEMP/WIND/SKY GRIDS OVER THE NEXT FEW HOURS TO
ACCOUNT FOR LATEST OBSERVED TRENDS...NO CHANGES HAVE BEEN MADE TO
THE FORECAST. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS...

LAST NIGHT`S COLD FRONT IS STALLING ABOUT 200 MILES OFF THE COAST.
THE FLOW ALOFT STILL HAS A SIGNIFICANT CYCLONIC CURVATURE...AND A
SERIES OF SHORTWAVES ARE ANALYZED UPSTREAM OF THE CAROLINAS. ONE
DISTURBANCE CURRENTLY OVER COASTAL GEORGIA WILL MOVE NORTHEASTWARD
ALONG THE COAST OVERNIGHT...INDUCING SURFACE LOW PRESSURE TO DEVELOP
ALONG THE STALLED FRONT OFFSHORE. IN RESPONSE TO THE APPROACHING
DISTURBANCE SHALLOW ISENTROPIC LIFT SHOULD DEVELOP ALONG THE COAST
BETWEEN THE 295K-300K SURFACES... ROUGHLY BETWEEN 4000-8000 FT
AGL...WITH CLOUDS AND SOME PATCHY LIGHT RAIN PROBABLY DEVELOPING
AFTER MIDNIGHT. I HAVE INCREASED RAINFALL CHANCES TO 20-30 PERCENT
ACROSS COASTAL SE NORTH CAROLINA BUT MAINTAINED A DRY FORECAST
ELSEWHERE AS IT APPEARS THE ISENTROPIC LIFT WILL BE WEAKER AND
SHOULD INVOLVE MAINLY DRY/UNSATURATED PARCEL MOTION.

WITH CLOUDS EXPECTED TO DEVELOP ALONG THE COAST I HAVE NUDGED
FORECAST LOWS UP BY A COUPLE OF DEGREES...ESPECIALLY NEAR
WILMINGTON...WITH SMALLER OR NO CHANGES MADE ELSEWHERE. LOWS SHOULD
REACH THE MID 40S INLAND ALONG I-95...WITH UPPER 40S TO LOWER 50S
EXPECTED ALONG THE COAST.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...ALTHOUGH MODEL SOLUTIONS ARE CONGEALING ON
SATURDAY THERE ARE STILL SOME MINOR DIFFERENCES. SUCH DIFFERENCES
WITH SUCH A STRONG SYSTEM HOWEVER CAN TRANSLATE TO CONSIDERABLE
FORECAST UNCERTAINTIES. FOR EXAMPLE, THE GFS HAS SHOWN A BIT OF A
WARM SECTOR/TROWAL BRIEFLY GETTING INTO MAINLY COASTAL NC ZONES AT
12Z SATURDAY...LIKELY DICTATING WHAT HIGH TEMPS ARE FOLLOWED BY
QUITE A DROP OFF IN THE CAA. AGREEMENT HAS ALSO INCREASED IN THE
PORTRAYAL OF DRY SLOT MOVING INTO SRN ZONES TO KEEP HIGHER QPF OVER
NRN ZONES. AREAS FURTHER SOUTH SHOULD STILL SEE SOME LIGHT RAIN
GIVEN THE STRENGTH OF THE FORCING BUT SHOULD LARGELY MISS OUT ON THE
DEEP MOISTURE. TIGHTLY WOUND SYSTEM SO THE WRAP-AROUND MOISTURE
ALREADY UNDERWAY BY AFTERNOON AND ONCE AGAIN MORE WIDESPREAD AND W
HIGHER AMOUNTS POSSIBLE NC. WINTER-LIKE COLD WITH MOST PLACES STUCK
IN THE LOW 50S SAVE FOR POSSIBLE EARLY DAY HIGHS ALONG THE COAST.
THERE STILL MAY BE A WINDOW OF OPPORTUNITY FOR SOME GRAUPEL PELLETS
TO REACH THE GROUND BUT THEY SHOULD BE THE EXCEPTION AND NOT THE
RULE. THE CAA PLUNGES SAT NIGHT LOWS DOWN INTO THE 30S. SOME WIND
AND CLOUD COVER PREVENT RAD COOLING. THE UPPER WAVE MOVES OFFSHORE
BY 12Z SUNDAY ALLOWING FOR STRONG DRY AIR ADVECTION. NEARLY FULL SUN
EXPECTED WITH A DIMINISHING BREEZE AND TEMPS ONCE AGAIN WELL BELOW
CLIMO. SUNDAY NIGHT WILL BE A FEW DEGREES COOLER THAN SATURDAY NIGHT
ESPECIALLY INLAND WHERE WINDS MAY GO CALM. FOR A PERFECT RAD NIGHT
THE CENTER OF THE HIGH WOULD NEED TO HAVE BEEN CLOSER.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...THE ORIGINAL CHILLY HIGH STILL DIRECTLY
OVERHEAD ON MONDAY. HOWEVER BETWEEN WARMING ALOFT AS WELL AS SOLAR
INSOLATION MODERATING THE AIRMASS HIGH TEMPERATURES WILL END UP
CLOSER TO BUT STILL SHY OF CLIMO. BUILDING UPPER RIDGE TO OUR WEST
SPREADS OVERHEAD BY TUESDAY ALLOWING FOR SOME WEAK ONSHORE RETURN
FLOW AND HIGHS BACK IN THE 70S. ADDITIONAL MODERATION AND WEAK
ADVECTION SHOULD BRING AN EVEN MILDER WEDNESDAY AND MOISTURE RETURN
WILL ADD SOME CLOUD COVER. A WEAK UPPER DISTURBANCE MOVES THROUGH
WED NIGHT INTO THURSDAY AND TRIES TO TOUCH OFF A FEW SHOWERS.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 06Z...EXPECT VFR THROUGH THE VALID PERIOD AS HIGH PRESSURE
REIGNS OVER THE AREA.

VFR WILL PREVAIL WITH N-NE WINDS LESS THAN 10 KT OVERNIGHT...HIEST
ACROSS THE COASTAL TERMS. ALONG WITH LINGERING SCT/BKN MID TO HIGH
LEVEL CLOUDS AT TIMES...ESPECIALLY ACROSS THE COASTAL TERMINALS.
AFTER DAYBREAK...VFR WILL CONTINUE WITH SLIGHT BACKING OF THE
WINDS TO THE NNW-N AOB 12 KTS AS WEAK LOW PRESSURE MOVES BY
TRACKING NE ALONG THE STALLED OFFSHORE FRONT. SCT/BKN MID TO HIGH
LEVEL CLOUDS ARE EXPECTED THROUGHOUT THE DAY. WINDS TO ONLY DROP
TO AROUND 6 KT DURING THE EVENING HOURS.

EXTENDED OUTLOOK...MVFR/IFR CONDITIONS WITH SHOWERS THRU SAT.
BREEZY TO WINDY CONDITIONS TO DEVELOP ON SATURDAY AND PERSIST
INTO SUNDAY AFTER LOW PRESSURE DEVELOPS OFF THE CAROLINA
COASTS...BOMBS...AND ACCELERATES TO THE NE. VFR FOR MONDAY AND
TUESDAY AS THE CENTER OF STRONG HIGH PRESSURE MOVES OVERHEAD.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 PM THURSDAY...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO
THE FORECAST. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS...

A COLD FRONT IS STALLING OUT BEYOND THE GULF STREAM ABOUT 200 MILES
OFFSHORE. LOW PRESSURE IS EXPECTED TO DEVELOP ALONG THE FRONT
OVERNIGHT...WITH A BACKING TREND IN WIND DIRECTIONS AND INCREASING
TREND IN WIND SPEEDS EXPECTED. CURRENTLY WIND SPEEDS RANGE FROM ONLY
5-10 KNOTS ON THE BEACHES TO 15-20 KNOTS OUT AT 20 MILES DISTANCE
FROM SHORE...WITH SEAS 2-4 FEET. MODELS HAVE TRENDED A BIT FARTHER
WESTWARD WITH THE PRECIPITATION SHIELD ON THE WEST SIDE OF THE UPPER
LOW...AND I HAVE THEREFORE ADDED SHOWER CHANCES TO THE
FORECAST...MAINLY AFTER MIDNIGHT...WITH THE HIGHEST CHANCES IN THE
CAPE FEAR WATERS DUE TO THEIR MORE EASTWARD LOCATION.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...GALE WARNING LIKELY IN EFFECT FOR MOST IF NOT
ALL OF THE AREA FOR COLD SURGE THAT SHOULD REALIZE GALES BY SAT
EVENING OR NIGHT. ITS STILL ABOUT ONE FORECAST CYCLE TOO EARLY TO
RAISE THE WARNING ESPECIALLY GIVEN THE SMALL DIFFERENCES IN HOW THE
MODELS HANDLE THE OVERALL EVOLUTION OF THE CYCLONE. WINDS WILL BE NW
TO W AND THUS STRONGLY OFFSHORE THROUGHOUT WHICH COULD YIELD A
CONSIDERABLE WAVE SHADOW ALONG LAND UP AGAINST THE INCREASINGLY
LARGE AND STEEP WAVES AS ONE MOVES AWAY FROM THE COAST. LOCALLY
GENERATED SWAN DATA APPEARS TO BE HANDLING THIS OK...ALTHOUGH IT
WILL BE INTERESTING TO SEE HOW THE POSSIBLE DEEP MIXING OF WIND
GUSTS CAUSED BY COOL AIR OVER WARMER SSTS MANAGES TO BOLSTER SEAS.
STRONGEST OF THE LOW LEVEL JETTING APPEARS SLATED FOR SATURDAY
NIGHT. THEREAFTER THESE WINDS ALONG WITH SURFACE FLOW WILL BEGIN TO
ABATE ALBEIT VERY GRADUALLY AT FIRST. THIS TREND WILL BE MORE
NOTICEABLE ON SUNDAY AS THE LOW CONTINUES TO BOTH DEEPEN AND
ACCELERATE OFF TO THE NORTHEAST.



LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...NORTHERLY WINDS REALLY RELAX ON MONDAY AS HIGH
PRESSURE MOVES OVER THE COAST. WIND DIRECTION MAY VEER SLIGHTLY AS
WELL WHILE SEAS SETTLE TO JUST 2 FT OR LESS. THE ACTUAL CENTER OF
THE HIGH DOES NOT MOVE MUCH INTO TUESDAY BUT IT DOES TAKE ON AN
EAST-WEST ELONGATION THAT WILL FURTHER TURN THE FLOW MOVE ONSHORE.
SEAS GENERALLY UNCHANGED AND MINIMAL IN SIZE.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...GALE WATCH FROM SATURDAY MORNING THROUGH LATE SATURDAY NIGHT
     FOR AMZ254-256.

     GALE WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY MORNING FOR
     AMZ250-252.

&&

$$
SYNOPSIS...MBB
NEAR TERM...DCH/TRA
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...DCH/SGL








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