Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 310233
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1033 PM EDT WED JUL 30 2014

.SYNOPSIS...
SEASONABLE WEATHER WILL CONTINUE THROUGH THURSDAY AS CANADIAN HIGH
PRESSURE SETTLES ACROSS THE AREA. A COASTAL FRONT WILL LIFT NORTH
ACROSS THE AREA FRIDAY AND INTO THE WEEKEND...BRINGING GOOD RAIN
CHANCES INTO EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 1030 PM WEDNESDAY...SHOWERS ARE STILL ONGOING ACROSS
BENNETTSVILLE AND THE RED SPRINGS AREA OF ROBESON COUNTY. THESE
SHOWERS REMAIN QUITE SHALLOW DUE TO THE SUBSIDENCE INVERSION ALOFT
WITH RADAR CROSS-SECTIONS SHOWING ECHO TOPS AROUND 20KFT AND ALL
HIGH REFLECTIVITY AT OR BELOW THE FREEZING LEVEL. (THE FREEZING
LEVEL IS CURRENTLY AROUND 14600 FT)  MODELS ARE NOT HANDLING THE
CURRENT ACTIVITY WELL AND EVEN THE HRRR IS NOT INDICATING NEARLY
ENOUGH ACTIVITY ON ITS LATEST FEW RUNS. I HAVE EXPANDED FORECAST
POPS INTO THE EARLY MORNING HOURS THURSDAY...WITH DRY CONDITIONS
DEVELOPING EVEN ACROSS NORTHERN ROBESON/NORTHERN BLADEN COUNTIES BY
2-3 AM. CLOUD COVER HAS ALSO BEEN INCREASED VERSUS THE PREVIOUS
FORECASTS WHICH MAY LEAD TO SLIGHTLY WARMER TEMPERATURES OVERNIGHT
DUE TO LESS RADIATIONAL COOLING. PREVIOUS DISCUSSION FROM 700 PM
FOLLOWS...

A CLOSED LOW AT 500 MB BETWEEN THE GREAT LAKES AND HUDSON BAY IS
MAINTAINING A LONGWAVE TROUGH OVER EASTERN NORTH AMERICA. OBSERVED
850 MB TEMPERATURES OF +14 TO +15C ARE A FEW DEGREES BELOW NORMAL
TOO...AND TODAY`S HIGH TEMPERATURES WERE ANYWHERE FROM 2 TO 5
DEGREES BELOW NORMAL FOR THE DATE. A SUBSIDENCE INVERSION JUST BELOW
700 MB HAS BEEN FAIRLY SUCCESSFUL AT CAPPING OFF THE VERTICAL GROWTH
OF SHOWERS TODAY. ONLY A HANDFUL OF THESE SHOWERS HAVE BROKEN THE
CAP AND GROWN INTO DEEPER THUNDERSTORMS. AS THE BOUNDARY LAYER COOLS
THIS EVENING THE FUEL FOR THESE CONVECTIVE SHOWERS SHOULD
DISSIPATE...WITH PREDICTED SHOWER CHANCES DROPPING TO BARELY 10
PERCENT BY MIDNIGHT.

A STALLED FRONT EXTENDING FROM NEAR THE FLORIDA GEORGIA LINE TO THE
GULF STREAM WATERS OFF SOUTH CAROLINA MARKS THE EDGE OF TROPICAL AIR
AT THE SURFACE. OUR AIRMASS IS HEAVILY MODIFIED CONTINENTAL POLAR
AIR THAT HAS SPENT THE PAST DAY TRAVERSING THE SEASONABLY WARM WATER
OFF THE MID-ATLANTIC COAST. WHILE CONVECTIVE CLOUDINESS SHOULD
DIMINISH OVERNIGHT MODELS ARE SHOWING FAIRLY GOOD CHANCES FOR CLOUDS
REMAINING AT LEAST ACROSS THE SC PEE DEE REGION...POTENTIALLY
SPREADING EASTWARD TO NEAR THE COAST AS WELL. WEAK ISENTROPIC LIFT
DEVELOPING NEAR THE BASE OF THE SUBSIDENCE INVERSION ALOFT SHOULD
INGEST A FEED OF ATLANTIC MOISTURE MOVING ONTO THE GEORGIA AND SOUTH
CAROLINA COAST...LIFTING IT UP THROUGH THE 800-750 MB LAYER
OVERNIGHT. THE LIFT IS QUITE WEAK AND WERE IT NOT FOR ITS RICH
MOISTURE CONTENT IT PROBABLY WOULD NOT BE WORTH MENTIONING. I HAVE
INCREASED CLOUD COVER FORECASTS ALONG THE I-95 CORRIDOR OVERNIGHT AS
A RESULT.

LOW TEMPERATURES SHOULD STILL REACH THE UPPER 60S FOR MOST INTERIOR
LOCATIONS...WITH 70-75 EXPECTED AT THE COAST IN AN ONSHORE FLOW.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
AS OF 3 PM WEDNESDAY...EXPECT TEMPERATURES TO BE SLIGHTLY BELOW
NORMAL THROUGH THE PERIOD. H5 TROF ACROSS HUDSON BAY IN CANADA
STARTS TO LIFT TO THE NE TURNING THE UPPER LEVEL FLOW FROM NW
AROUND TO THE SW BY FRIDAY AND A WARM MOIST TRANSPORT OF AIR IS
ADVECTED INTO THE REGION BUT THIS WILL BE OFFSET AS COASTAL TROUGH
PUSHES ONSHORE DURING FRIDAY AND INCREASED CLOUD COVER AND POPS
WILL HELP TO KEEP TEMPS AGAIN SLIGHTLY BELOW NORMAL. ON THURSDAY
REGION STARTS TO SEE AN INCREASE IN PWAT AT THIS TIME I HAVE
SCALED BACK ON THE THREAT OF ANY PRECIPITATION UNTIL THE NIGHT
TIME WITH A BETTER CHANCE BY FRIDAY. HAVE TAKEN A BLEND OF THE
NAM/GFS SOLUTION FOR TEMPS/POP BUT HAVE FAVORED THE HIGHER POPS
FROM THE GFS ON FRIDAY AS INCREASED MOISTURE TRANSPORT INTO THE
REGION AHEAD OF COASTAL TROF MOVING ONSHORE SHOULD ENHANCE
PRECIPITATION THREAT ACROSS REGION. THIS WILL ALSO HELP IN KEEPING
TEMPS BELOW NORMAL ACROSS THE REGION AGAIN. PWAT INCREASE ON
FRIDAY TO AROUND 2 INCHES ALONG WITH UPPER LEVEL DYNAMICS TO
INCREASE POPS TO OVER 40 PERCENT BY AFTERNOON.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 3 PM WEDNESDAY...UPPER TROUGH AXIS TO OUR WEST SATURDAY AND
SUNDAY WHILE SURFACE BOUNDARY SLOWLY PUSHES INLAND. STAGE IS SET
FOR SOME FAIRLY WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY WHILE
CLOUD COVER INHIBITS DAYTIME HIGHS FROM REACHING CLIMO NORMS. MID
LEVEL TROUGH AND SURFACE BOUNDARY BOTH WASH OUT AS MONDAY
PROGRESSES BUT THERE STILL SHOULD BE ENOUGH DEEP SOUTHWESTERLY
FLOW FOR A SIMILAR FORECAST. TUESDAY HAD PREVIOUSLY LOOKED LIKE A
MORE TYPICAL AUGUST DAY BUT MODELS ARE A LITTLE SLOWER WITH THE
MID LEVEL VEERING AND STILL SHOW SOME WEAK VORTICITY CENTERS
PASSING OVERHEAD. FEEL IT MAY BE BEST TO STILL SHOW A HIGHER THAN
CLIMO POP-BUT LOWER THAN PREVIOUS DAYS. WILL ALSO SHOW RISING
AFTERNOON HIGHS. WEDNESDAY LOOKS SEASONABLE FOR THE MOST PART
ALTHOUGH SOME DEEP MOISTURE MAY BE LINGERING OVER FAR SOUTHERN
ZONES.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 00Z...VFR THIS TAF VALID PERIOD...EXCEPT FOR A SHORT PERIOD OF
SUB-VFR VSBYS IN THE PRE-DAWN HOURS AT KFLO/KLBT.

ESE WINDS WILL BECOME LGT/VRB FOR THE EVENING AND OVERNIGHT HOURS AT
KFLO/KLBT...AND LIGHT NE AT KCRE/KMYR/KILM. ONLY LIMITED AMOUNTS OF
LOW LEVEL MOISTURE IS AVAILABLE FOR BR FORMATION. BEST TIME FRAME
FOR DECREASED VSBYS SHOULD BE 08-12Z AT KFLO/KLBT. ALTHOUGH THE BEST
MOISTURE IS AT KFLO...A BROKEN LAYER OF MID CLOUDS IS FCST BY SREF
TO PERSIST THROUGH MUCH OF THE OVERNIGHT MAINLY AT AT KFLO.
THEREFORE BELIEVE THE CHANCE OF IFR IS LOW AT KFLO...AND LOW AT KLBT
DUE TO LESS AVAILABLE MOISTURE. AT THE COASTAL TERMINALS THERE
SHOULD BE ENOUGH WIND OVERNIGHT TO MITIGATE FOG FORMATION.

MID LEVEL CLOUDS SCT NEAR KFLO DURING THE MORNING. SCT LOW AND MID
CLOUDS...WITH THIN BKN HIGH CLOUDS EXPECTED FOR MOST OF THE DAY.
WINDS WILL BE LIGHT...THEN BECOME E-ESE AT ALL TERMINALS DURING THE
MORNING...WITH STRONGEST SPEEDS AT THE COASTAL TERMINALS.

EXTENDED OUTLOOK...INCREASING CHANCES FOR SHRA/TSRA AND PERIODS OF
MVFR CONDITIONS FRIDAY THROUGH MONDAY AS A FRONT STALLS OVER THE
EASTERN CAROLINAS.
&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM WEDNESDAY...LATEST OBSERVATIONS SHOW SEAS HAVE BUILT
TO NEARLY 4 FEET NORTH OF CAPE FEAR...WITH 3 FOOT SEAS NOW SHOWING
UP AT THE SUNSET BEACH BUOY. SINCE THAT LOCATION IS NORMALLY QUITE
PROTECTED FROM INCOMING SWELL I HAVE INCREASED CONFIDENCE TO
INCREASE SEA HEIGHT FORECASTS TO A SOLID 4 FEET FROM CAPE FEAR
NORTHWARD...AND 3 FEET SOUTH OF CAPE FEAR. WINDS AT BUOYS AND
COASTAL STATIONS ARE RUNNING 2-3 KNOTS HIGHER THAN EARLIER FORECAST
WHICH PROBABLY EXPLAINS THE SEA HEIGHT DISCREPANCY. PREVIOUS
DISCUSSION FROM 700 PM FOLLOWS...

EASTERLY WINDS ARE EXPECTED OVERNIGHT BETWEEN HIGH PRESSURE ACROSS
VIRGINIA AND A STALLED FRONT EXTENDING FROM THE FLORIDA GEORGIA LINE
TO THE GULF STREAM WATERS OFF THE SOUTH CAROLINA COAST. WIND SPEEDS
SHOULD AVERAGE 10-15 KNOTS WHICH IS HELPING SUSTAIN A 2-3 FOOT
5-SECOND WIND CHOP. WHEN COMBINED WITH A SMALL SOUTHEAST 9-SECOND
SWELL...COMBINED SEAS SHOULD AVERAGE AROUND 3 FEET. ALTHOUGH A
RENEGADE SHOWER CANNOT BE COMPLETELY RULED OUT...THE BETTER CHANCES
FOR SHOWERS APPEAR TO ACROSS INTERIOR SOUTH CAROLINA THIS EVENING.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...BETTER CHANCE OF POPS ACROSS THE COASTAL
WATERS THIS PERIOD AS STALLED FRONT/COASTAL TROUGH WILL BE PUSHED
BACK TOWARDS THE COAST THURSDAY BEFORE MOVING ONSHORE DURING
FRIDAY. WINDS WILL REMAIN AT OR BELOW 10 KTS WITH WEAK GRADIENT ON
THURSDAY BUT INCREASE FRIDAY WITH COASTAL TROF MOVING ONSHORE.
WINDS MAINLY E TO SE ON THURSDAY VEERING TO THE S-SW BY FRIDAY.
WAVES WILL AVERAGE 2-3 FT SEAS THROUGH THE PERIOD.

LONG TERM /SATURDAY THROUGH SUNDAY/...
AS OF 3 PM WEDNESDAY...LIGHT SE WINDS ON SATURDAY AS FRONTAL
BOUNDARY JUST INLAND FROM THE COAST MOVES FURTHER WEST. SEAS AROUND
3 FT FOR THE MOST PART AS WIND WAVES QUITE LIGHT BUT WNA SPECTRAL
PLOTS SHOWING A SEERLY SWELL. HEADING INTO SUNDAY A MINOR VEER TO
THE S AS THE BOUNDARY MOVES FURTHER INLAND AND WEAKENS ALLOWING WEST
ATLANTIC HIGH PRESSURE TO BECOME MORE PREDOMINANT WITH LOCAL WIND
GENERATION. SEAS RELATIVELY UNCHANGED. AS THIS TREND CONTINUES INTO
MONDAY A SIMILAR ONE COMPASS POINT VEER TO SW CAN BE EXPECTED. THERE
MAY BE AN OUTSIDE CHANCE FOR SOME ADDITIONAL SWELL ENERGY SHOULD THE
ATLANTIC TROPICAL DISTURBANCE STRENGTHEN BUT THIS SYSTEM HAS BEEN
STRUGGLING TO DEVELOP AND ITS FUTURE PATH AND STRENGTH STILL PRETTY
UP IN THE AIR.
&&

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

&&

$$

SYNOPSIS...CRM
NEAR TERM...TRA
SHORT TERM...MAC
LONG TERM...MBB
AVIATION...MRR





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