Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 270832 CCA
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
415 AM EDT THU AUG 27 2015

.SYNOPSIS...
A FRONT WILL OSCILLATE ALONG THE COAST THROUGH TODAY WHILE GRADUALLY
LOSING IDENTITY BEFORE IT SHIFTS FURTHER OFF THE COAST BY THE
WEEKEND. HIGH PRESSURE WILL SLOWLY BUILD INTO THE CAROLINAS THIS
WEEKEND. ERIKA IS EXPECTED TO APPROACH THE BAHAMAS AND SOUTH FLORIDA
LATE IN THE WEEKEND INTO EARLY NEXT WEEK AND POSSIBLY AFFECT THE
CAROLINAS BY NEXT WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 125 AM THURSDAY...HAVE LOWERED POPS WELL INLAND...AND
INCREASED THEM SLIGHTLY ALONG THE IMMEDIATE COAST. BOTH CHANGES
BASED ON LATEST KLTX AND SURROUNDING 88D TRENDS.

PREVIOUS......................................................
AS OF 1030 PM WEDNESDAY...NO CHANGES TO THE FORECAST WITH THE
LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS:

ISOLATED SLOW MOVING CONVECTION CONTINUES NEAR THE COAST ALONG
THE STALLED FRONTAL BOUNDARY. AT PRESENT ACTIVITY IS CONCENTRATED
OVER PENDER AND GEORGETOWN COUNTIES. MINOR LOCALIZED FLOODING
SEEMS TO BE THE PRIMARY THREAT FOR THE NEXT FEW HOURS. HAVE
LOWERED POPS BASED ON PRESENT TRENDS...ALTHOUGH KEEPING LOW CHANCE
POPS IN FOR THE COASTAL COUNTIES OVERNIGHT BASED ON LATEST
GUIDANCE...THE PROXIMITY OF THE FRONT...AND A JUICY...UNSTABLE
ATMOSPHERE WITH THE OCCASIONAL UPPER DISTURBANCE MOVING THROUGH
OVERHEAD. PREVIOUS DISCUSSION FOLLOWS:

STATIONARY FRONT ALIGNED VERY NEAR THE COAST IS SLOWLY BEING
ABSORBED/COMBINED WITH THE SEA BREEZE WHICH IS JUST NOW BEGINNING TO
DEVELOP. THIS LATE START TO HEATING IS DUE TO THE PRONOUNCED CLOUD
COVER FROM THIS MORNING (POST FRONTAL STRATUS AND ANVIL DEBRIS) THAT
ONLY RECENTLY ERODED. WHILE HEATING HAS BEEN SLOW...IT IS STILL VERY
UNSTABLE OUTSIDE WITH SPC MESOANALYSIS SHOWING 2000-3000 J/KG OF
SBCAPE ALONG THE EASTERN COUNTIES. THIS IS HIGHLY UNSTABLE...SO ANY
UPDRAFTS FORCED BY SURFACE BASED CONVERGENCE ALONG THE SEA
BREEZE...FRONT...OR DIFFERENTIAL HEATING BOUNDARIES...ARE STILL
EXPECTED TO RISE QUICKLY INTO TSTMS. ADDITIONALLY...A SHORTWAVE
EVIDENT ON WV IMAGERY LIFTING NE FROM THE GULF COAST WILL COMBINE
WITH ENHANCING DIFFLUENCE AT 300 MB TO PROVIDE UPPER SUPPORT. IN
OTHER WORDS...ALL SIGNS STILL POINT TO CONVECTION BLOSSOMING THIS
EVENING...AND HIGH RES GUIDANCE...WHILE NOT AS AGGRESSIVE AS EARLIER
STILL SHOWS SCATTERED TO WIDESPREAD CONVECTION DEVELOPING THROUGH
THIS EVENING. HAVE TRIMMED POP BACK TO HIGH CHC FROM THE EARLIER
LIKELY...BUT MANY PLACES STILL FACE THE RISK OF TORRENTIAL RAINFALL
WITH ISOLATED FLOODING...SIGNIFICANT LIGHTNING...AND MAYBE AN
ISOLATED DAMAGING WIND GUST.

POP WILL WANE SLOWLY AFTER DARK WITH LOSS OF HEATING...BUT THE
PRESENCE OF THE UPPER FEATURES WILL HAVE THE POTENTIAL TO MAINTAIN
CONVECTION THROUGH THE OVERNIGHT HOURS...ALTHOUGH IN A WEAKER AND
LESS WIDESPREAD FASHION.

TEMPS TONIGHT WILL FALL SLOWLY AS CLOUDS AND SOUTHERLY WINDS EAST OF
THE FRONT MAINTAIN A VERY WARM AND HUMID AIRMASS. A SIGNIFICANT TEMP
GRADIENT IS FORECAST ACROSS THE CWA FOR MINS...DROPPING TO AROUND 69
WELL INLAND...BUT STAYING AS WARM AS 75 ALONG THE IMMEDIATE COAST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 330 AM THURSDAY...LINGERING FRONT/TROUGH MAY BE A FEW
HUNDRED MILES OFF THE CAPE FEAR COAST ON FRI LEAVING A WEAK
NORTHEAST FLOW...BUT LOOKS LIKE BROADER HIGH PRESSURE WILL BEGIN
TO PRODUCE A MORE EASTERLY FLOW INTO THE SOUTHEAST STATES BY
SATURDAY. THE DRIER NORTHEAST FLOW ON FRI SHOULD KEEP PCP WATER
VALUES DOWN NEAR 1.5 INCHES CLOSER TO THE COAST AND DIMINISHING
INLAND. THE GREATEST MOISTURE WILL BE ALONG THE COAST AND AS SEA
BREEZE DEVELOPS...SHOULD SEE ENOUGH LIFT AND MOISTURE TO PRODUCE
SOME CONVECTION...BUT NOT EXPECTING IT TO BE TOO WIDESPREAD.

BY SATURDAY...THE GREATER ON SHORE PUSH WILL INCREASE MOISTURE
THROUGH THE COLUMN. WINDS MAY STILL REMAIN OUT OF THE NE
MAINTAINING A DRIER FLOW OVER NC INITIALLY IN THE MORNING...BUT BY
THE END OF SATURDAY...PCP WATER VALUES SHOULD BE UP NEAR 1.9
INCHES ACROSS THE AREA. THEREFORE EXPECT GREATER POTENTIAL FOR
MORE WIDESPREAD CONVECTION ON SATURDAY. TEMPERATURES WILL RUN
NEAR NORMAL.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 330 AM THURSDAY...LONG TERM FORECAST TOTALLY DEPENDS ON
EVOLUTION OF ERIKA...WHICH...AT THIS POINT IS VERY UNCERTAIN. NHC
FORECAST KEEPS ERIKA ON A ROUTE UP THROUGH THE BAHAMAS AND
REACHING OFF THE FLORIDA COAST BY MON EVE. THE TROPICAL MODEL
GUIDANCE WAS TAKING THIS TRACK AS WELL...BUT THE LATEST ECMWF AND
GFS TRACK ERIKA FARTHER WEST AND KEEP IT WEAKER...WHILE THE
PREVIOUS RUNS PRODUCED A HURRICANE OVER CAPE FEAR BY NEXT
WEDNESDAY. WITH SUCH INCONSISTENCIES AT THIS TIME...WILL REMAIN
MORE CONSERVATIVE AND WILL KEEP WITH MORE OF AN ON SHORE AND THAN
NORTHERLY FLOW AS IF ERIKA WAS TRACKING OFF THE COAST TO OUR EAST.
WE WILL HAVE TO MONITOR ERIKA QUITE CLOSELY. LOOKS LIKE GREATEST
EFFECTS FROM ERIKA MAY BE EXTREME RUSH OF MOISTURE INTO THE
CAROLINAS WITH GUSTY WINDS AND SWELLS AND STRONG ON SHORE PUSH
AFFECTING THE COASTAL WATERS. ALSO EXPECT AN ELEVATED RIP CURRENT
THREAT AS EARLY AS THE LATTER HALF OF THE WEEKEND. FOR NOW WILL GO
WITH PLENTY OF CLOUDS THROUGH MOST OF THE PERIOD WITH DIURNAL
CONVECTION AND GREATEST POPS FOR TUES INTO WED. TEMPS WILL REMAIN
AROUND CLIMO WITH MAX TEMPS IN THE UPPER 80S TO AROUND 90 AND MINS
IN THE 70S.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 06Z...DEBRIS CLOUDS WILL KEEP FOG ALONG THE COAST AT A
MINIMUM...HOWEVER WITH ALL THAT WATER ON THE GROUND ESPECIALLY
ACROSS COASTAL HORRY...SOME IFR CONDITIONS COULD OCCUR WITH ANY
GRADUAL CLEARING OR THE COOL FRONT MOVES FURTHER OFF THE SC
COAST. SOME LIGHT TO MODERATE FOG INLAND TERMINALS ALONG WITH
MVFR TO POSSIBLY IFR STRATUS EXPECTED INTO DAYTIME THU MORNING.
SHOULD BECOME PREDOMINATELY VFR BY MID TO LATE MORNING ACROSS ALL
TERMINALS WITH NORTHEAST FLOW DOMINATING. COULD SEE ESE-SSE FLOW
ALONG THE IMMEDIATE COAST DUE TO THE SFC FRONTS PARTIAL
OSCILLATION ACROSS THE REGION.

WITH THE FRONT OSCILLATING NEAR THE COAST...INSTEAD OF FURTHER
INLAND...WILL LEAN TOWARD VCNTY CONVECTION INLAND FOR THE AFTN AND
EARLY EVENING...AND TRY TO IDENTIFY A PREDOMINATE TIME FOR
CONVECTION AT THE COAST. BEST COVERAGE SHOULD REMAIN ALONG THE
IMMEDIATE COAST WITH THE COASTAL TERMINALS UNDER THE GONE FOR
THURSDAYS THREAT FOR CONVECTION.

EXTENDED OUTLOOK...PREDOMINATELY VFR WITH ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE EXTENDED. BRIEF MORNING
FOG/STRATUS IS ALSO EXPECTED EACH DAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 06Z...DEBRIS CLOUDS WILL KEEP FOG ALONG THE COAST AT A
MINIMUM...HOWEVER WITH ALL THAT WATER ON THE GROUND ESPECIALLY
ACROSS COASTAL HORRY...SOME IFR CONDITIONS COULD OCCUR WITH ANY
GRADUAL CLEARING OR THE COOL FRONT MOVES FURTHER OFF THE SC
COAST. SOME LIGHT TO MODERATE FOG INLAND TERMINALS ALONG WITH
MVFR TO POSSIBLY IFR STRATUS EXPECTED INTO DAYTIME THU MORNING.
SHOULD BECOME PREDOMINATELY VFR BY MID TO LATE MORNING ACROSS ALL
TERMINALS WITH NORTHEAST FLOW DOMINATING. COULD SEE ESE-SSE FLOW
ALONG THE IMMEDIATE COAST DUE TO THE SFC FRONTS PARTIAL
OSCILLATION ACROSS THE REGION.

WITH THE FRONT OSCILLATING NEAR THE COAST...INSTEAD OF FURTHER
INLAND...WILL LEAN TOWARD VCNTY CONVECTION INLAND FOR THE AFTN AND
EARLY EVENING...AND TRY TO IDENTIFY A PREDOMINATE TIME FOR
CONVECTION AT THE COAST. BEST COVERAGE SHOULD REMAIN ALONG THE
IMMEDIATE COAST WITH THE COASTAL TERMINALS UNDER THE GONE FOR
THURSDAYS THREAT FOR CONVECTION.

EXTENDED OUTLOOK...PREDOMINATELY VFR WITH ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE EXTENDED. BRIEF MORNING
FOG/STRATUS IS ALSO EXPECTED EACH DAY.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 330 AM THURSDAY...LINGERING FRONT/TROUGH SHOULD BE JUST EAST
OF WATERS ON FRI WITH MORE OF A NE WIND FLOW. HIGH PRESSURE OVER
ATLANTIC WITH CENTER TO THE NORTH OF AREA WILL BECOME MORE
DOMINANT BY LATE SAT INTO SUNDAY ALLOWING WINDS TO SHIFT TO THE
E THROUGH SUNDAY AND E-SE BY SUN NIGHT. OVERALL EXPECT WINDS TO
REMAIN 10 KTS OR LESS WITH A SPIKE EACH AFTN IN SEA BREEZE.
KEEPING SEAS 2 TO 3 FT WITH A LONGER PERIOD SWELL MIXING IN WITH
SHORTER PERIOD WIND WAVES.

LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 330 AM THURSDAY...LONG TERM FORECAST BECOMES MORE DEPENDENT
ON TRACK OF ERIKA. OVERALL EXPECT ON SHORE PUSH WITH EASTERLY
WINDS AROUND 10 KTS AND SEAS REMAINING LESS THAN 4 FT THROUGH
MUCH OF THE PERIOD. BY TUES MORNING...SEAS MAY BEGIN TO RAMP UP AS
WINDS AND SWELLS FROM ERIKA BEGIN TO AFFECT THE AREA. LOOKS LIKE
GREATEST AFFECT FROM ERIKA ACROSS THE LOCAL AREAS WILL COME TUES
INTO WED....BUT MODEL INCONSISTENCIES MAY MAKE IT A BIT MORE
DIFFICULT TO FORECAST.

&&

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

&&

$$

NEAR TERM...DCH
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...DCH/DL




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