Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 220255
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1055 PM EDT TUE OCT 21 2014

.SYNOPSIS...
A STRONG COLD FRONT WILL PUSH ACROSS THE AREA AND OFFSHORE LATE
TONIGHT. COOLER THAN NORMAL AND DRY CONDITIONS WILL FOLLOW THROUGH
THE MID TO LATE WEEK PERIOD AS THE FORECAST AREA REMAINS UNDER
CYCLONIC FLOW SURFACE AND ALOFT. BROAD HIGH PRESSURE ACCOMPANIED
WITH SEASONABLE TEMPERATURES AND CONTINUED DRY WEATHER WILL PREVAIL
ACROSS THE FORECAST REGION FRIDAY THROUGH THE UPCOMING WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 1030 PM TUESDAY...MAIN OBJECTIVE CONTINUES TO BE THE TIMING
AND STRENGTH OF THE COLD FRONTAL PASSAGE. LATEST SFC PRESSURE
PROG CONSENSUS INDICATES THE SFC FRONT TO DROP SE AND PUSH THROUGH
AND OFF THE ILM CWA COAST BY MID-LATE EVENING. LIKE THE PREVIOUS
CFP...THE CAA SURGE IS PROGGED TO LAG 3 TO 6 HRS BEHIND THE
INITIAL CFP. THEREFORE...DURING THE PRE-DAWN WED HRS...THE SFC PG
WILL TIGHTEN AND COMBINE WITH THE CAA SURGE TO PRODUCE A NW WIND
AT 10 TO 15 MPH...WITH BRIEF GUSTS UP TO 20 MPH MAINLY ALONG THE
IMMEDIATE COAST. THIS WILL KEEP THE ATM WELL MIXED WITH NO
LIKELIHOOD OF FOG. THE MOISTURE PROFILES ACROSS THE ILM CWA WILL
REMAIN SHALLOW AND LOW LEVEL...ENOUGH FOR CLOUD DEVELOPMENT BUT NO
WHERE DEEP ENOUGH FOR ORGANIZED PCPN OCCURRENCE. THIS ILLUSTRATED
WELL WITH VARIOUS MODEL TIME HEIGHT DISPLAYS FOR LOCATIONS ACROSS
THE ILM CWA. OF NOTE...MODEST MID-LEVEL S/W TROFS WILL PUSH ACROSS
THE FA AND RESULT IN SOME WEAK UVVS...JUST NOT ENUF MOISTURE TO
SQUEEZE OUT FOR PCPN. TWEAKED MIN TEMPS AND OVERNIGHT SFC
DEWPOINTS SLIGHTLY LOWER RESPECTIVELY DUE TO LATEST TRENDS.
SUBSEQUENT SFC RH AND APPARENT TEMP FIELDS ADJUSTED.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 230 PM TUESDAY...MID AND UPPER LOW WILL DOMINATE THE PICTURE
WEDNESDAY/THURSDAY AS IT MOVES OFF THE VIRGINIA CAPES TO OFF THE
JERSEY SHORE. TIME-HEIGHT CROSS SECTIONS SHOW A VERY DRY COLUMN
ABOVE H85 WITH STRONG SUBSIDENCE WITH DEEP NORTHWEST FLOW THROUGH
THE MID AND UPPER LEVELS. THE PRECIPITABLE WATER WILL ONLY REACH A
HALF INCH WEDNESDAY FOLLOWED BY 0.4 INCHES THURSDAY. THIS PATTERN
WILL HOLD MAX TEMPS TO JUST BELOW NORMAL WEDNESDAY...WHILE A SURGE
IN COOL SFC-LOW LEVEL AIR WEDNESDAY NIGHT WILL SOMEWHAT HINDER
RADIATIONAL COOLING. THINK RADIATIONAL COOLING WILL BE MORE OF A
FACTOR THURSDAY NIGHT THUS MET/MAV MIGHT BE A CATEGORY TOO WARM MOST
LOCATIONS BY THAT TIME.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 230 PM TUESDAY...THE DRY PERIOD WILL CONTINUE WITH PLEASANT
FALL WEATHER ANTICIPATED THROUGH THE EXTENDED. AMPLIFIED MID-LEVEL
PATTERN WILL GRADUALLY DE-AMPLIFY AS AN ANOMALOUSLY STRONG CUTOFF
FILLS AND MOVES AWAY FROM NEW ENGLAND. LOCALLY...THIS LEAVES AN
EXTENDED PERIOD OF NW FLOW ALOFT...WITH WEAK IMPULSES SERVING AS
REINFORCING SHOTS OF COOL AIR INTO EARLY NEXT WEEK. THE AIR MASS
WILL REMAIN EXCEEDINGLY DRY HOWEVER...WITH PWATS REMAINING BELOW
0.75 INCHES THE ENTIRE PERIOD...AND FALLING TO AS LOW AS 0.30 INCHES
LATE IN THE WKND. IF THESE VERY LOW PWATS VERIFY...THEY WILL
APPROACH ALL-TIME LOW THRESHOLDS FOR LATE OCTOBER ACROSS THE AREA.
IN OTHER WORDS...NO PRECIP WILL BE POSSIBLE INTO EARLY NEXT WEEK.
VERY LATE IN THE PERIOD THE SURFACE HIGH PRESSURE WILL PUSH OFFSHORE
AS RIDGING BEGINS TO DEVELOP OVER THE SOUTHEAST...THIS WILL DRIVE
SOME RETURN FLOW INTO THE CAROLINAS...BUT MOISTURE RETURN WILL
REMAIN TOO LOW FOR ANY PRECIP. THE DRY AIR MASS IN PLACE WILL ALLOW
FOR A LOT OF SUNSHINE...AND THUS WHILE HIGHS WILL RISE TO CLIMO OR
ABOVE EACH DAY...OVERNIGHT MINS WILL DROP BELOW CLIMO INTO NEXT
WEEK...WARMING BY TUESDAY.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
AS OF 00Z...A WEAK RADIATIONAL INVERSION IS SETTING UP...BUT IT ONLY
SHOULD LAST THROUGH ABOUT 05-06Z AS A DRY COLD FRONT PASSES THROUGH
THE REGION. POST FRONTAL...EXPECT NORTHWEST WINDS TO PICK UP. WILL
TAKE  THE GUSTS OUT DUE TO THE DIURNAL NATURE OF THE PASSAGE. A
BRIEF VFR STRATOCU CEILING IS POSSIBLE. WEDNESDAY...VFR WITH A GUSTY
NORTHWEST FLOW. ONLY SCATTERED CU IS EXPECTED.

EXTENDED OUTLOOK...EXPECT VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 PM TUESDAY...WILL HOLD OFF WITH RAISING A SCEC THIS
PACKAGE. BUT IN ALL LIKELIHOOD...A BRIEF SCEC MAY BE NEEDED
COMMENCING LATER TONIGHT OR THE ENSUING 1 TO 2 PERIODS. MODEST CAA
SURGE DELAYED AFTER MIDNIGHT TONIGHT COMBINED WITH A TIGHTENING
SFC PG AS DEEP LOW PRESSURE DEVELOPS OFF DELMARVA LATE TONIGHT...
INTENSIFIES AS IT PUSHES SLOWLY TOWARD THE NE DURING THE NEXT FEW
DAYS. MODEL TIME HEIGHT DISPLAYS ACROSS THE COASTAL WATERS
INDICATE 25 TO 35 KT NW WINDS JUST OFF THE DECK LATE TONIGHT AND
WELL INTO THE SHORT TERM PERIOD. EXPECT THE MIXING OF THESE WINDS
DOWN TO THE OCEAN SFC AS 25 TO POSSIBLY 30 KT WIND GUSTS FOR
EITHER LATE TONIGHT OR INTO THE SHORT TERM PERIOD.

SIGNIFICANT SEAS WILL BASICALLY BUILD TO 2 TO 4 FT...WITH 5
FOOTERS APPEARING LATE TONIGHT AND/OR THE ENSUING 1 TO 2 PERIODS.
THEIR OCCURRENCE WILL BE OFF CAPE FEAR...AND THE OUTER WATERS OFF
THE MOUTH OF WINYAH BAY. LOCALLY PRODUCED WIND DRIVEN WAVES WILL
DOMINATE THE SEAS SPECTRUM...WITH VERY LITTLE INPUT IN THE FORM OF
A GROUND SWELL. DOMINANT PERIODS WILL RANGE BETWEEN 3 AND 6
SECONDS.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 230 PM TUESDAY...COLD AIR ADVECTION ACROSS RELATIVELY WARM
OCEAN TEMPERATURES WILL EQUATE TO GUSTY OFFSHORE FLOW ACROSS THE
COASTAL WATERS WEDNESDAY. THE OFFSHORE FLOW WILL PERSIST INTO
THURSDAY BUT SPEEDS WILL DIMINISH AS THE COLD AIR ADVECTION WEAKENS
ACROSS THE AREA. A RANGE OF SEAS WILL EXIST FROM THE COAST TO THE 20
NM WATERS GIVEN THE OFFSHORE FLOW. SEAS WILL BE HIGHEST WEDNESDAY...
THEN SUBSIDE AS THE AFOREMENTIONED OFFSHORE FLOW WEAKENS DURING
THURSDAY. WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT THRESHOLDS EACH
DAY.

LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 230 PM TUESDAY...STRONG LOW PRESSURE DRIFTING SLOWLY AWAY
FROM NEW ENGLAND...AND BROAD HIGH PRESSURE RIDGING NORTHEAST FROM
THE GULF COAST...KEEPS RATHER UNIFORM FLOW THROUGH THE PERIOD.
WINDS BETWEEN THESE TWO FEATURES WILL REMAIN FROM THE NW
FRIDAY...SATURDAY...AND MOST OF SUNDAY...BEFORE THE HIGH PRESSURE
INCHES OFF THE COAST CAUSING WINDS TO TURN MORE TO THE N/NE. THE
GRADIENT REMAINS SLACK HOWEVER...SO SPEEDS WILL BE AROUND 10 KTS
EACH DAY. THE COMBINATION OF THE OFFSHORE WIND COMPONENT...LIGHT
SPEEDS...AND LACK OF SIGNIFICANT SWELL...WILL KEEP WAVE HEIGHTS AT
1-3 FT THROUGH THE PERIOD...WITH THE 3 FTERS CONFINED TO THE OUTER
PORTION OF THE 0-20NM WATERS.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...DCH/SRP
NEAR TERM...DCH/RGZ
SHORT TERM...SRP
LONG TERM...JDW
AVIATION...DCH/DL




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