Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 282347
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
747 PM EDT FRI AUG 28 2015

.SYNOPSIS...
HIGH PRESSURE OVER THE MID-ATLANTIC REGION WILL BRING FAIR
WEATHER THROUGH SATURDAY. INCREASING MOISTURE FROM THE GULF OF
MEXICO COULD BRING SHOWERS AND ISOLATED THUNDERSTORMS TO THE
AREA SUNDAY INTO MONDAY. ERIKA...OR THE REMNANTS OF ERIKA...WILL
APPROACH FLORIDA EARLY NEXT WEEK...POSSIBLY TRACKING INTO THE
NORTHERN GULF OF MEXICO AFTERWARD.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 745 PM FRIDAY...NOT MUCH TO CHANGE THIS EVENING AS FAR AS
THE FORECAST GOES. STILL EXPECTING A DRY AND RELATIVELY COOL
OVERNIGHT WITH CIRRUS STREAMING OVERHEAD THROUGH THE PERIOD.
RELEVANT PORTION OF PREVIOUS DISCUSSION FOLLOWS:

SOME COMFORTABLE AIR PUSHING INTO THE REGION ON A NORTHEASTERLY
POST-FRONTAL FLOW. THIS IS EXPECTED TO CONTINUE THROUGH THE PERIOD
AND MAINTAIN THE EAST-WEST DEWPOINT GRADIENT IN PLACE. AREA-WIDE
THIS WILL TEND TO MEAN IT IS TOO DRY FOR ANY PRECIPITATION AND
EVEN THE SEA BREEZE FAILED TO DO SO DURING PEAK HEATING (THOUGH
THERE WERE A FEW SPRINKLES ACRS PARTS OF GTOWN AND HORRY).
SIMILARLY IT WILL BE TOO DRY FOR `NORMAL` FOG (BELOW ABOUT 1 SM).
THE MOISTURE GRADIENT WILL ALSO PLAY INTO NIGHTTIME LOWS WHICH
WILL RANGE LOW TO MID 60S FAR NW TO LOW 70S FAR SRN SC COAST.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...CLEMENT WEATHER ON TAP SATURDAY AS DIMINISHING
BUT POSITIVE HEIGHT CHANGES ALOFT ALLOWS DRY AIR TO DOMINATE THE
ATMOSPHERIC LAYER FROM 750-500 MB MUCH OF THE WEEKEND START. LAND
BREEZE CONVERGENCE AND FRONTAL BOUNDARY OFFSHORE MAY SPUR MARINE
CONVECTION INTO EARLY SATURDAY BUT THE BULK SHOULD REMAIN AT SEA.

MOISTURE RETURN BECOMES EVIDENT IN VERTICAL RH PLOTS THROUGH TIME
BY EARLY SUNDAY...AS A SERIES OF PERTURBATIONS ALOFT BEGIN TO RISE
OUT OF THE NE GULF OF MEXICO AROUND AN UPPER RIDGE WEAKNESS/GAP.
NAM-12 LAYER PRECIPITABLE WATER PROGNOSTICATIONS SHOW PWAT VALUES
SOARING TO 2.0-2.15 BY SUNDAY AFTERNOON SWAMPING INTO THE REGION.
THIS SHOULD BE SUFFICIENTLY AMPLE TO FUEL SCATTERED CONVECTION IN
DIURNAL HEATING PROCESSES AND SUBSEQUENT SFC BOUNDARY GENERATION.

NO SHOCKERS IN MAX/MIN TEMPERATURE EXPECTATIONS...WITH NEAR CLIMO
TYPE READINGS OF UPPERS 80S AWAY FROM THE BEACHES IN THE AFTERNOON
AND UPPER 60S TO LOWERS 70S EARLY MORNING...BEACHES 75-85 RANGE.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 3 PM FRIDAY...ALL EYES WILL BE ON TROPICAL STORM ERIKA NEXT
WEEK AS SHE MEANDERS SLOWLY TOWARDS THE SOUTHEAST UNITED STATES.
UNFORTUNATELY...ERIKA HAS REALLY STRUGGLED TO GET HER ACT TOGETHER
AND REMAINS TODAY IN A VERY UNFAVORABLE ENVIRONMENT DUE TO SHEAR AND
MOUNTAINOUS TERRAIN ACROSS HISPANIOLA. THIS BEING THE CASE MODEL
SPREAD OF HER EVOLUTION IS MUCH LARGER THAN TYPICAL...AND THUS THE
EXTENDED REMAINS A PRETTY BIG QUESTION MARK.

WHILE THE TREND HAS BEEN FOR A WEAK AND FURTHER WEST SYSTEM...THAT
DOES NOT MEAN THE CAROLINAS WILL REMAIN UNSCATHED.  WHILE THE
POSITION OF ERIKA...AS WELL AS THE INTENSITY OF THE SYSTEM...REMAIN
VERY MUCH IN QUESTION...EVEN THE FURTHER SW TRACK SHOWN BY THE
GFS/ECM BRINGS THE POTENTIAL FOR SIGNIFICANT RAINFALL INTO OUR AREA.
ANY CLOSER TRACK OR STRONGER SYSTEM WOULD OF COURSE INCREASE THE
IMPACTS LOCALLY. NOTE THAT GUIDANCE HAS WIDESPREAD PWAT OVER 2
INCHES WED/THU/FRI THANKS TO LONG TROPICAL MOISTURE FETCH FROM THE
CARIBBEAN. WHILE MONDAY AND TUESDAY MAY FEATURE TYPICAL
SUMMERTIME CONVECTION...POSSIBLE AIDED BY A WEAK MID-LEVEL
DISTURBANCE ON MONDAY...THE MORE ACTIVE WEATHER IS SLATED FOR WED-
FRI. STILL MUCH UNCERTAINTY AND A LOT CAN CHANGE BUT WILL RAMP UP
POP TO MID-CHC FOR WED-FRI AS EVEN IF ERIKA WEAKENS AND STAYS WELL
SW OF THE AREA...A GOOD MOISTURE FETCH SEEMS LIKELY.

TEMPS THROUGH THE PERIOD WILL BE AROUND CLIMO...BUT MAY FALL SHORT
OF NORMAL WED-FRI DEPENDING ON CLOUD COVER AND RAIN.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 00Z...EXPECT VFR THROUGH THE VALID PERIOD AS HIGH PRESSURE
CONTINUES TO BUILD SOUTH INTO THE AREA AS FRONTAL SYSTEM REMAINS
STALLED JUST OFFSHORE.

VFR PREVAILS ACROSS THE AREA THIS EVENING WITH SCT/BKN LOW AND HIGH
CLOUDS AND NORTHEAST WINDS AOB 8 KTS. EXPECT WINDS TO BECOME LIGHT
AND VARIABLE INTO THE OVERNIGHT HOURS WITH MAINLY HIGH CLOUDS.
GUIDANCE IS SUGGESTING POSSIBLE FOG DEVELOPMENT...MAINLY AT KLBT
OVERNIGHT. HOWEVER GIVEN LOWER CONFIDENCE...HAVE NOT INTRODUCED ANY
MVFR INTO GOING TAFS ATTM. ON SATURDAY...EXPECT VFR TO PREVAIL WITH
EAST-NORTHEAST WINDS AOB 12 KTS AND A GRADUAL INCREASING TREND OF
HIGH CLOUD COVERAGE.

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 745 PM FRIDAY...LATEST OBS SHOW NE WINDS OF AROUND 15 KTS
WITH 3 TO 4 FT SEAS. EXPECT LITTLE CHANGE FROM THESE CONDITIONS
FOR THE OVERNIGHT PERIOD.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...MANAGEABLE WEEKEND MARINE CONDITIONS EXPECTED
WITH NE WINDS 10-15 KT MUCH OF THE WEEKEND...EXCEPT BECOME E-SE
NEAR SHORE DURING THE MIDDLE AFTERNOON TO VERY EARLY EVENING
RESULTING FROM THE SEA BREEZE CIRCULATION. SYNOPTIC WIND
DIRECTION WILL BECOME SE 10 KT SUNDAY LATE AFTERNOON AND EVENING
AS WEAK HIGH PRESSURE SLIPS OFFSHORE. SEAS 3-4 FEET EVERY 9-10
SECONDS WITH A LIGHT TO MODERATE NE CHOP MOST OF THE WEEKEND.
ISOLATED MARINE TSTMS WILL DOT THE WATERS OVER THE WEEKEND.

LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 3 PM FRIDAY...BIG CHANGES WITH THIS FORECAST PACKAGE...AS
WIND/WAVE ENERGY FROM TROPICAL STORM ERIKA IS LOOKING MUCH LESS
AMPLIFIED LOCALLY. WITH ERIKA A WEAKER SYSTEM...AND EXPECTED NOW
TO MOVE WELL SW OF THE AREA...DIRECT SWELL AND STRONG WINDS SEEM
UNLIKELY. THIS BEING THE CASE...THE PRIMARY WAVE GROUP MAY END UP
BEING A SE GROUND SWELL OF 9-11 SEC...ESPECIALLY SINCE WINDS WILL
BE LIGHT AND VARIABLE FROM SE TO NE THROUGH THE MIDDLE OF THE
WEEK. THIS SWELL WILL CREATE WAVE HEIGHTS OF 2-4 FT ON
MONDAY...BEFORE FALLING TO 2-3 FT TUESDAY AND WEDNESDAY. OF
COURSE...ANY SIGNIFICANT DEVIATION FROM THE TRACK OF ERIKA COULD
CHANGE THIS...BUT NEEDED TO RAMP SEAS DOWN CONSIDERABLY FROM
INHERITED AS ANY ADVISORY LEVEL WAVES ARE NO LONGER ANTICIPATED.

&&

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

&&

$$

SYNOPSIS...MJC
NEAR TERM...REK/MBB
SHORT TERM...MJC
LONG TERM...JDW
AVIATION...SGL
MARINE...MJC/REK/JDW/MBB


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