Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 012346
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
646 PM EST SUN FEB 1 2015

.SYNOPSIS...
RAIN AND GUSTY WINDS WILL SLOWLY MOVE INTO THE REGION OVERNIGHT
AHEAD OF A COLD FRONT WHICH WILL MOVE THROUGH LATE MONDAY MORNING.
HIGH PRESSURE WILL BUILD INTO THE AREA TUESDAY AND WEDNESDAY. AS
THE FRONT SITS OFFSHORE LATE IN THE WEEK A FEW AREAS OF LOW PRESSURE
DEVELOPING ALONG IT MAY BRING UNSETTLED WEATHER.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 PM SUNDAY...DESPITE THE COMPLEXITY OF THIS FORECAST VERY
FEW CHANGES WERE NEEDED WITH THIS EARLY EVENING NEAR-TERM UPDATE.
LOW TEMPERATURES SHOULD OCCUR EARLY TONIGHT...WITH INCREASING
SOUTH-SOUTHWEST WINDS ADVECTING WARMER AIR IN FROM GEORGIA. LATEST
NEAR-TERM HIGH-RES GUIDANCE INDICATES TWO REGIONS TO WATCH FOR
DEVELOPING SHOWERS: ONE OFF THE GA/SC COAST DUE TO SOUTH WIND ACROSS
THE WESTERN EDGE OF THE GULF STREAM ENHANCING LOW-LEVEL
INSTABILITY...AND A SECOND AREA ASSOCIATED WITH THE MAIN STORM
SYSTEM OFF TO OUR WEST. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS...

SIGNIFICANT BREAKS IN THE CLOUD COVER AND INCREASING SOUTHERLY WINDS
HAVE ALLOWED TEMPS TO REACH THE LOWER TO MID 60S. A DEVELOPING
SEABREEZE THIS AFTERNOON WILL DROP TEMPS BACK INTO THE 50S AT THE
BEACHES.

LOW PRESSURE WILL INTENSIFY AS IT MOVES ACROSS THE OHIO RIVER VALLEY
TONIGHT AND THE NORTHEAST STATES ON MON. A STRONG ATTENDANT COLD
FRONT...APPROACHING FROM THE WEST...WILL BRING STRONG WINDS TO THE
AREA OVERNIGHT AND ON MON. THE COLD FRONT WILL BE LOCATED JUST TO
THE WEST OF OUR MOST INLAND COUNTIES AT DAYBREAK MON. AS A SW LOW
LEVEL JET...50+ KT AT 1500 FT AGL...IMPINGES ON THE AREA
OVERNIGHT...WIND GUSTS TO 35 TO 40 MPH ARE EXPECTED TO DEVELOP. WE
WILL TAP GULF OF MEXICO AND ATLANTIC MOISTURE AHEAD OF THE FAST
MOVING SYSTEM AND WITH THAT...PRECIPITABLE WATER VALUES WILL PEAK
NEAR ONE AND A THIRD INCHES LATE TONIGHT AND MON MORNING. WE SHOULD
GET A RATHER QUICK SHOT OF SHOWERS IN THE WARM AND MOIST RETURN
FLOW ALONG AND AHEAD OF THE SURFACE FRONT. CONFIDENCE IS HIGH
MEASURABLE RAINFALL WILL OCCUR AND WILL INCLUDE CATEGORICAL POPS.
RAINFALL AMOUNTS SHOULD BE ON THE ORDER OF A QUARTER OF AN INCH.

INSTABILITY IS CERTAINLY LACKING THROUGH A DEEP LAYER AND EVEN
ELEVATED INSTABILITY IS NOT BEING DEPICTED BY THE MODELS.
THUS...EVEN THOUGH THIS SYSTEM IS VERY DYNAMIC...DID NOT INCLUDE
MENTION OF THUNDERSTORMS AT THIS TIME.

WE WILL BE UNDER THE INFLUENCE OF WARM AIR ADVECTION THROUGH THE
NIGHT. CLOUDS WILL THICKEN UP THIS EVE AND OVERNIGHT AND WINDS WILL
INCREASE. THESE FACTORS WILL RESULT IN A NON-DIURNAL TEMP CURVE.
LOWS WILL BE ACHIEVED THIS EVE IN MOST LOCATIONS WITH RISING TEMPS
OVERNIGHT. TEMPS MAY FALL BACK A DEGREE OR TWO IN ANY PERSISTENT
SHOWERS. EVE LOWS MAINLY IN THE LOWER TO MID 50S WILL CLIMB INTO THE
UPPER 50S AND LOWER 60S OVERNIGHT.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 PM SUNDAY...VERY STRONG LOW LEVEL JET IN PLACE AT THE START
OF THE PERIOD AHEAD OF COLD FRONT AND MID LEVEL TROUGH/SHORTWAVE. WE
WILL BE CLOSE TO MEETING WIND ADVISORY CRITERIA DEEPENING ON THE
MAGNITUDE AND DEPTH OF VERTICAL MIXING. RIGHT NOW THERE ARE JUST
ENOUGH CONFLICTING SIGNALS TO PRECLUDE ONE. FOR EXAMPLE THE GFS HAS
OVERALL WEAKER LOW LEVEL WIND FIELDS THAN THE WRF...COMPARABLY WEAK
LOW LEVEL LAPSE RATES...YET STRONGER SURFACE WINDS IN ITS MOS OUTPUT
(ITS MOS BULLETINS ACTUALLY MARGINALLY SUPPORT A ROUGH RULE OF THUMB
FOR WIND ADVISORY). ALTHOUGH THE STRONGEST LOW LEVEL WIND FIELDS
OCCUR DURING THE MORNING HOURS IN THE PREFRONTAL AIRMASS THERE MAY
BE ANOTHER OPPORTUNITY FOR ADVISORY-WORTHY WINDS IN THE LATE MORNING
AND EARLY AFTERNOON. THE POST-FRONTAL AIRMASS WILL YIELD SOME
STEEPER LAPSE RATES MORE CONDUCIVE TO VERTICAL MIXING BUT AS
MENTIONED THE BL WINDS WILL BE WANING, EVEN IF SOMEWHAT GRADUALLY.
EVEN DEEPER MIXING MAY BE ENCOURAGED BY THE FAIRLY POTENT SHORTWAVE
IMPINGING UPON THE REGION. AFTER COLLAB WITH NEIGHBORS WE HAVE ALL
DECIDED TO HOLD OFF ON ANY ADVISORY FOR NOW. THE BEST CHANCE FOR
ADVISORY LEVEL WINDS MAY BE IN THE SHORT OVERLAP BETWEEN THE TWO
AFOREMENTIONED OPPORTUNITIES AS WELL AS UNDERNEATH ANY DEEPER
CONVECTIVE SHOWERS...BOTH PROBABLY TOO LOCALIZED AND SHORT-LIVED TO
WARRANT AT THIS TIME. IT WILL OTHERWISE BE A RATHER MILD MORNING
WITH A FEW LIGHT TO MODERATE SHOWERS BUT DRY AIR WILL BE VERY
QUICKLY MOVING IN FROM THE NORTH AND WEST. GUIDANCE NOT TOO KEEN ON
FALLING PM TEMPERATURES FOR MOST OF THE AFTERNOON BUT BY EVENING THE
COOL ADVECTION WILL BE QUITE NOTICEABLE ESPECIALLY SINCE IT WILL
STILL BE QUITE BREEZY. PRETTY QUIET ALBEIT QUITE CHILLY FOR THE
REMAINDER OF THE PERIOD AS HIGH PRESSURE BUILDS OVERHEAD BY DAYBREAK
WEDNESDAY. IN FACT WOULD NOT BE SURPRISED IF WE HAVE TO TWEAK
TUESDAY NIGHT LOWS DOWN A BIT A RADIATIONAL COOLING MAY BE IN THE
CARDS.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 3 PM SUNDAY...ANTICIPATED SOUTHERN STREAM SYSTEM EJECTING FROM
THE SOUTHWEST CONTINUES TO BE A KEY FEATURE IN THE LONG TERM
FORECAST. MEDIUM RANGE GUIDANCE CONTINUES HAVING TROUBLE WITH THE
INTERACTION OF THE SOUTHERN STREAM SYSTEM AND A WEAKER NORTHERN
STREAM SHORTWAVE DROPPING IN FROM THE UPPER MIDWEST. THE PATTERN OF
LIMITED RUN TO RUN CONSISTENCY AND MINIMAL AGREEMENT BETWEEN THE
OPERATIONAL GUIDANCE IS LIKELY TO CONTINUE UNTIL THE NORTHERN STREAM
WAVE IS SAMPLED BY THE UPPER AIR NETWORK IN ANOTHER DAY OR TWO.

A GOOD PORTION OF THE ENSEMBLES FAVOR A SOLUTION WITH SOME
INTERACTION BETWEEN THE NORTHERN AND SOUTHERN STREAMS BUT MOST FALL
SHORT OF FULL PHASING. THE INHERITED FORECAST IS IN LINE WITH THE
LATEST OPERATIONAL GFS...MOST OF THE GFS ENSEMBLES AND THE WPC
SOLUTIONS...WHICH HAVE LESS AMPLIFICATION OF THE 5H PATTERN MID
WEEK. THE RESULT? PRECIP CHANCES WILL INCREASE LATE WED NIGHT AS
GULF MOISTURE SPREADS NORTHEAST AHEAD OF THE GULF COAST SHORTWAVE.
BEST PRECIP CHANCES WILL BE THU INTO THU NIGHT BEFORE THE 5H TROUGH
SWEEPS A STRONG COLD FRONT ACROSS THE AREA EARLY FRI MORNING
MAINTAINING BELOW CLIMO TEMPS FRI INTO SAT. TEMPERATURES START A
SLOW CLIMB BACK TO CLIMO NEXT WEEKEND AS SURFACE HIGH MODERATES
UNDER DEEP NORTHWEST FLOW ALOFT.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AS OF 00Z...MODERATE TO HIGH CONFIDENCE TERMINALS WILL REMAIN VFR
THROUGH 07Z WITH LIGHT RAIN BECOMING LIKELY BY 04Z. AFTER 07Z TEMPO
MVFR CIGS AND/OR MVFR VSBYS IN LIGHT RAIN WILL BE POSSIBLE...BUT
PREDOMINANT MVFR CIGS/VSBYS SHOULD HOLD OFF UNTIL 12Z OR THEREAFTER.
LOW LEVEL WINDS WILL BE INCREASING OVERNIGHT AND WILL INCREASE TO 35
KT BY 06Z AND TO 40-50 KT BELOW 2K FEET BY 12Z. LLWS SEEMS LIKELY
AFTER 06Z BUT WILL WAIT FOR 06Z TAFS TO BETTER DEFINE LEVELS.

AFTER 12Z EXPECT THE BEST CHANCE OF RAIN...MVFR FLIGHT CONDITIONS
AND LLWS AS A COLD FRONT RAPIDLY APPROACHES. THE CHANCE OF IFR
APPEARS LOW ATTM. AS THE COLD FRONT MOVES THROUGH AROUND 15Z AT
KFLO/KLBT AND AROUND 17Z AT THE COASTAL TERMINALS...RAIN SHOULD END
AND VFR DEVELOP...WITH GUSTY WNW WINDS.

EXTENDED AVIATION OUTLOOK...VFR WITH COASTAL SHOWERS POSSIBLE THURS.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 PM SUNDAY...NEARSHORE WINDS ARE SOUTH AT BARELY 5 KNOTS
WHILE OVER THE WARMER WATER AT FRYING PAN SHOALS BUOY GUSTS ARE
REACHING 23 KNOTS. THIS DIFFERENCE IN ATMOSPHERIC STABILITY WILL
CONTINUE OVERNIGHT WITH LARGE IMPACTS ON WIND SPEEDS OBSERVED AT THE
SURFACE. GALE-FORCE WINDS WILL LIKELY BE CONFINED TO AREAS WHERE
WARM SST`S PROMOTE MIXING DOWN OF STRONGER WINDS FROM ALOFT...WHILE
NEARSHORE THE COLDER WATER WILL PRODUCE A STABLE BOUNDARY LAYER WITH
SOMEWHAT WEAKER WIND SPEEDS EXPECTED. REGARDLESS...INCREASING WINDS
WILL DEVELOP OVERNIGHT WITH DANGEROUS SEAS EXPECTED...PERHAPS AS
HIGH AS 10 FEET BY DAYBREAK ACROSS THE OUTER PORTION (15-20 MILES
OUT) OF THE COASTAL WATERS. ASIDE FROM REDUCING FORECAST NEARSHORE
WIND SPEEDS THROUGH ABOUT 2 AM AND SLOWING DOWN THE GROWTH OF
FORECAST SEAS UNTIL WINDS ACTUALLY INCREASE...NO SIGNIFICANT CHANGES
WERE NEEDED TO THE FORECAST WITH THIS EARLY EVENING NEAR-TERM
UPDATE.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 PM SUNDAY...GALE WARNING IN EFFECT THROUGH MONDAY NIGHT.
DESPITE THERE STILL BEING SOME QUESTION REGARDING VERTICAL TRANSPORT
OF MOMENTUM SOME GUIDANCE NOW SHOWING LOW LEVEL 925MB JET SLIGHTLY
EXCEEDING HURRICANE FORCE OVER THE WATERS FROM 12Z-16Z. WITH SUCH A
STRONG WIND FIELD IN PLACE EVEN WEAK MIXING SHOULD READILY SUPPORT
GALES...NOT TO MENTION SOME VERY LARGE AND DANGEROUS WAVES. IN FACT
THE COOL SSTS IS THE MAIN/ONLY REASON THAT A SHORT DURATION STORM
WARNING NOT WARRANTED...THOUGH NOT OUT OF THE QUESTION EITHER. THE
PRECIPITOUS VEER ASSOCIATED WITH THE MIDDAY FROPA WILL STEEPEN THE
STILL LARGE WAVE FACES AND IT SEEMS THAT WNA GUIDANCE AND SWAN ARE
BOTH TOO QUICK TO KNOCK SEAS DOWN EVEN GIVEN THE OFFSHORE TRAJECTORY
THROUGH MONDAY NIGHT. THAT SAID MARINERS WILL HAVE TO WAIT UNTIL
TUESDAY FOR MUCH IMPROVED WEATHER AND NO HEADLINES OR FLAGS.

LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 3 PM SUNDAY...LIGHT RETURN FLOW AROUND WEST SIDE OF SURFACE
HIGH WELL OFF THE NC COAST INCREASES LATE WED NIGHT AND BECOMES
NORTHWEST AS COLD FRONT MOVES ACROSS THE AREA. STRONG NORTHERLY FLOW
CONTINUES THU AND THU NIGHT WITH WINDS VEERING NORTHEAST LATE IN THE
DAY. COMBINATION OF PINCHED GRADIENT AND COLD ADVECTION WILL LEAD TO
SPEEDS APPROACHING AND THEN EXCEEDING 25 KT LATE THU AND THU NIGHT.
PINCHED GRADIENT REMAINS IN PLACE FRI AND NORTHEAST FLOW WILL REMAIN
20 TO 25 KT THROUGH THE END OF THE PERIOD. BENIGN SEAS WED INTO THU
WILL RAMP UP THU AND THU NIGHT IN RESPONSE TO INCREASED WIND SPEEDS.
OFFSHORE COMPONENT MAY INITIALLY KEEP SEAS ABOVE 6 FT BEYOND 20 NM
BUT EXTENDED DURATION OF ELEVATED WIND SPEEDS COMBINED WITH
DEVELOPING NORTHEAST FLOW LATE THU WILL RESULT IN SEAS OVER 6 FT FOR
THE SECOND HALF OF THE PERIOD. EXTENDED PERIOD OF SCA HEADLINE
BEGINNING LATE THU SEEMS ALMOST CERTAIN.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...GALE WARNING FROM 11 PM THIS EVENING TO 1 AM EST TUESDAY
FOR      AMZ250-252-254-256.

&&

$$

SYNOPSIS...MBB/TRA
NEAR TERM...RJD
SHORT TERM...MBB
LONG TERM...III
AVIATION...MRR




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