Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 041123
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
723 AM EDT MON MAY 4 2015

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO DRIFT SLOWLY OFFSHORE EARLY TO
MID-WEEK...PROVIDING SUNSHINE AND SEASONABLE MAY TEMPERATURES. A
COASTAL LOW IS EXPECTED TO FORM IN THE BAHAMAS MID-WEEK...AND
MEANDER ALONG THE SOUTHEAST COAST THROUGH THE END OF THE WEEK AND
INTO NEXT WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM MONDAY...DRY AND SEASONABLE WEATHER WILL CONTINUE AS
HIGH PRESSURE SLIPS FARTHER OFF SHORE WHILE CONTINUING TO RIDGE
BACK INTO THE CAROLINAS. THIS WILL PROVIDE A LIGHT RETURN FLOW
WITH A SLIGHT INCREASE IN MOISTURE. TEMPS DROPPING EARLY THIS
MORNING WILL CREATE SOME VERY SHALLOW FOG BUT OVERALL COLUMN WILL
REMAIN VERY DRY WITH ONLY LIMITED LOW LEVEL MOISTURE. A MID TO
UPPER RIDGE TRIES TO BUILD OVERHEAD...BUT A SHORTWAVE RIDING DOWN
FROM THE NW WILL DISRUPT THIS RIDGE AS IT MOVES SLOWLY OVER THE
COASTAL CAROLINAS THROUGH THIS AFTERNOON WITH TROUGH BECOMING
STRETCHED OUT ALONG THE COAST TONIGHT. AS THIS SHORTWAVE MOVES
THROUGH IT WILL PRODUCE SOME PASSING MID LEVEL CLOUDS.

THE LIGHT RETURN FLOW AROUND THE SFC HIGH WILL COMBINE WITH
AFTERNOON SEA BREEZE TO GIVE IT A STRONG PUSH INLAND THROUGH THE
AFTERNOON. CONVERGENCE ALONG THE SEA BREEZE AND THE WESTERN
PERIPHERY OF HIGH PRESSURE WILL HELP BUILD SOME AFTERNOON CU. THE
SHORTWAVE SHOULD ACT TO ENHANCE THE VERTICAL GROWTH A BIT...BUT A
STRONG SUBSIDENCE INVERSION AROUND 8-9 K FT WILL CAP OFF THE
CLOUDS AND LIMIT CHC OF SHWRS. THE HRRR TRIES TO GENERATE A FEW
STRAY SHOWERS INLAND THIS AFTERNOON BUT BELIEVE THIS WILL JUST END
UP BEING CLUSTERS OF CU.

HUGE DIURNAL RANGES WILL CONTINUE WITH TEMPS STARTING OUT IN THE
MID 50S THIS MORNING AND REACHING UP TO AROUND 80 EXCEPT SLIGHTLY
COOLER AT THE BEACHES. CONTINUED ON SHORE FLOW AROUND HIGH WILL
SUPPORT A SLOW RISE IN DEWPOINTS TONIGHT AFTER A DIURNAL DROP THIS
AFTERNOON IN DEEPER MIXING. THIS WILL KEEP OVERNIGHT LOWS A FEW
DEGREES HIGHER...BUT STILL DOWN TO 55 TO 60 MOST PLACES WITH IDEAL
RADIATIONAL COOLING CONDITIONS UNDER CLEAR SKIES AND NEAR CALM
WINDS. MAY SEE SOME PATCHY SHALLOW GROUND FOG AGAIN TONIGHT AS TEMPS
DROP OUT BUT COLUMN WILL BE VERY DRY ABOVE THE SURFACE.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 AM MONDAY...BERMUDA HIGH ON TUESDAY WILL RETREAT WEDNESDAY
AHEAD OF DISTURBANCE EMERGING FROM THE CARIBBEAN AND THE BAHAMAS.
MID LEVEL RIDGING IN PLACE ABOVE THE BERMUDA HIGH TUE WILL MAINTAIN
WARM AND DRY CONDITIONS ACROSS THE AREA WITH ONLY PATCHES OF SHALLOW
AFTERNOON CU. ONSHORE FLOW WILL CONTINUE KEEPING TEMPS NEAR THE
COAST AROUND CLIMO WHILE INLAND AREAS WARM UP A BIT.

SECOND HALF OF THE PERIOD STARTS TO GET INTERESTING AS THE SYSTEM
EMERGING FROM THE BAHAMAS WILL TRY AND COALESCE INTO A WELL DEFINED
LOW. THE GOING WILL INITIALLY BE SLOW AND THE LACK OF STEERING FLOW
ALOFT IS LIKELY TO KEEP THE SYSTEM SOUTH OF THE AREA THROUGH THE END
OF THE PERIOD. STILL A LOT OF UNCERTAINTY REGARDING THIS SYSTEM AND
WHILE IT MAY LEAD TO AN INCREASE IN CLOUD COVER...ESPECIALLY ALONG
THE COAST WED NIGHT...DO NOT THINK IT WOULD DIRECTLY AFFECT THE
REGION BEFORE THE END OF THE PERIOD. THUS WILL MAINTAIN THE DRY
FORECAST WITH HIGHS AROUND CLIMO AND LOWS A BIT ABOVE CLIMO.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 3 AM MONDAY...LONG TERM PERIOD WILL BE DOMINATED BY THE LOW
EVOLVING OFF THE SOUTHEAST COAST MID TO LATE WEEK. GUIDANCE
CONTINUES TO STRUGGLE WITH THIS SYSTEM...MAINLY DUE TO THE LACK OF
ANY REAL STEERING FLOW ALOFT. HOWEVER SOME SOLUTIONS SEEM HARD TO
BUY. FOR INSTANCE THE LOW DEEPENING AND MOVING UP THE COAST SEEMS
THE LEAST LIKELY OUTCOME GIVEN THE 5H RIDGING TO THE NORTH. DO THINK
THE LOW COULD GRADUALLY STRENGTHEN THROUGH THE PERIOD.

ALTHOUGH THE WATER TEMPS WITHIN THE GULF STREAM ARE AROUND 80 AND
SHEAR SHOULD BE WEAK TO NONEXISTENT THERE ARE SEVERAL FACTORS THAT
WOULD LIMIT STRENGTHENING. A LACK OF DIFFLUENCE ALOFT EARLY IN THE
PERIOD AND THE LARGE SWATH OF SEA SURFACE TEMPS OUTSIDE THE GULF
STREAM IN THE 60S BEING THE BIGGEST. SO WHILE SOME DEVELOPMENT OF
THIS SYSTEM IS EXPECTED A FULL BLOWN TROPICAL SYSTEM SEEMS TO BE A
LONG SHOT. INSTEAD THE SYSTEM WILL PROBABLY ACQUIRE SOME TROPICAL
CHARACTERISTICS BUT REMAIN QUITE WEAK AS IT WANDERS OVER THE WATERS
OFF THE SOUTHEAST COAST. WORTH NOTING A LOT OF THE GFS ENSEMBLES
TAKE THE WEAK LOW INTO FL OR SOUTHERN GA...SOMETHING WHICH A FAIR
NUMBER OF THE MEMBERS HAVE BEEN CONSISTENTLY SHOWING OVER THE LAST
FEW DAYS.

LOCALLY IMPACTS THROUGH THE PERIOD WILL BE NORTHEAST FLOW...WITH
SOME ENHANCEMENT LATER IN THE WEEK AND AN INCREASE IN LOW LEVEL
MOISTURE. THIS SHOULD BRING ABOUT AN INCREASE IN PRECIP
CHANCES...ESPECIALLY ALONG THE COAST...AS THE WEEK WEARS ON. GIVEN
THE LOW CONFIDENCE PLAN TO MAKE ONLY SMALL CHANGES TO THE INHERITED
FORECAST WHICH WILL NOW CARRY CHC POP THROUGH THE PERIOD WITH TEMPS
NEAR TO SLIGHTLY ABOVE CLIMO.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
AS OF 06Z...PERSISTENCE FORECAST REGARDING AVIATION PURPOSES.
BERMUDA HIGH PRESSURE WILL CONTINUE TO DOMINATE WX CONDITIONS
THROUGH THE PERIOD WITH  MOSTLY IFR CONDITIONS. SOME MODELS ARE
GENERATING A LITTLE SEA BREEZE ACTIVITY ACROSS SOUTH CAROLINA BUT
FEEL ANY ACTIVITY WILL BE TOO ISOLATED IN NATURE TO INCLUDE IN
FORECAST. ADDED A LITTLE BR TO FLO FOR THE OVERNIGHT HOURS PER
OBSERVATIONS THIS MORNING.

EXTENDED OUTLOOK...PRE-DAWN MORNING FOG IS POSSIBLE EACH DAY THAT
COULD RESULT IN MVFR/IFR CONDITIONS. UNSETTLED WEATHER THURSDAY
NIGHT THROUGH SATURDAY WITH A SUBTROPICAL LOW.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM MONDAY...HIGH PRESSURE WILL SHIFT FARTHER OFF SHORE
WHILE CONTINUING TO RIDGE BACK INTO THE COASTAL CAROLINAS.
THEREFORE EXPECT A VERY LIGHT RETURN FLOW TO CONTINUE BASICALLY
OUT OF THE SE-S LESS THAN 10 KTS. SEAS WILL RUN UNDER 3 FT MOST
WATERS WITH A A VERY SLOW DECLINE THROUGH TODAY WITH SUCH LIGHT
WINDS AND DIMINISHING LONGER PERIOD BACKSWELL FROM LOW MOVING OFF
INTO THE DISTANT ATLANTIC WATERS. THE WNA SHOWS LONGER PERIOD
SWELLS DROPPING OFF BY NOON TODAY WITH JUST SHORTER PERIOD WIND
WAVES DOMINATING ESPECIALLY AS SEA BREEZE DEVELOPS THIS AFTERNOON.
A PERSISTENT LIGHT ON SHORE RETURN FLOW WILL CAUSE A SLIGHT RISE
IN SEAS THROUGH TONIGHT. OVERALL EXPECT BENIGN SEAS AROUND 2 TO 3
FT OR LESS WITH A SLIGHT SPIKE NEAR SHORE IN AFTERNOON SEA BREEZE.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 AM MONDAY...BERMUDA HIGH WILL MAINTAIN LIGHT EASTERLY
FLOW TUE INTO WED. DURING THE SECOND HALF OF THE PERIOD THE HIGH
WILL RETREAT NORTHEAST AS WEAK LOW PRESSURE EMERGES FROM THE
BAHAMAS. WINDS WILL BACK TO NORTHEAST FOR WED AND WED NIGHT WITH A
SLIGHT BUMP IS SPEED. CONFIDENCE WITH RESPECT TO THE AMOUNT OF
STRENGTHENING THE LOW WILL UNDERGO AND ITS LOCATION IS RATHER LOW
AND THUS FORECAST CONFIDENCE IS ALSO LOW. FOR NOW KEEPING WIND
SPEEDS WED AND WED NIGHT CONFINED TO THE 15 TO 20 KT RANGE BUT
HIGHER VALUES ARE POSSIBLE. SEAS 2 TO 3 FT TUE INTO WED SHOULD
BUILD LATER WED AS NORTHEAST FLOW INCREASES AND COASTAL LOW STARTS
TO BECOME A LITTLE MORE DEFINED.

LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 3 AM MONDAY...MUCH OF THE FORECAST DEPENDS ON THE DETAILS
OF THE HYBRID TROPICAL SYSTEM MEANDERING OFF THE SOUTHEAST COAST
LATE THIS WEEK. WEAK STEERING FLOW ALOFT HAS SO FAR BEFUDDLED
GUIDANCE AND NOT CONFIDENT CLARITY WILL DESCEND UPON THE FORECAST
IN THE NEAR TERM. THAT SAID FEEL A FORECAST OF NORTHEAST FLOW IN
THE 15 TO 20 KT RANGE IS A GOOD COMPROMISE AND IS IN LINE WITH
PREVIOUS FORECASTS. SEAS WILL BUILD ON THE BACK OF EXTENDED
NORTHEAST FLOW WITH SOME ZONES LIKELY TO EXCEED 6 FT IN PLACES ON
THU AND REMAIN ABOVE 6 FT FRI.

&&

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

&&

$$
SYNOPSIS...SHK
NEAR TERM...RGZ
SHORT TERM...III
LONG TERM...III
AVIATION...SHK



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