Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 032317
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
717 PM EDT SUN MAY 3 2015

.SYNOPSIS...
THE CENTER OF A HIGH PRESSURE SYSTEM WILL DRIFT SLOWLY OFFSHORE
THROUGH EARLY THIS 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 /UNTIL 6 AM MONDAY MORNING/...
AS OF 715 PM SUNDAY...ALL IS QUIET THIS EVENING AS CLOUD COVER
FADES WITH THE SETTING SUN. HAVE SEEN NO REASON TO CHANGEFORECAST
ANY FOR THE NEAR TERM OTHER THAN TO TWEAK CLOUD COVER DOWNWARDS.
PREVIOUS DISCUSSION FOLLOWS:

DRY AND SEASONABLE WEATHER WILL CONTINUE THROUGH TONIGHT AS HIGH
PRESSURE SLIPS OFF SHORE WITH A LIGHT RETURN FLOW SETTING UP.
THERE WILL BE PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID TO
UPPER LEVELS WITH ONLY LIMITED LOW LEVEL MOISTURE THROUGH THE
COLUMN. THIS WILL ONLY ALLOW FOR SOME FLAT CU AS SOUNDINGS SHOW A
DECENT SUBSIDENCE INVERSION RIGHT AROUND 8-9K FT WHICH WILL LIMIT
THE VERTICAL GROWTH OF ANY CU.

AS THE CENTER OF THE HIGH REMAINS NEARLY OVERHEAD THIS
AFTERNOON...EXPECT A VERY WEAK GRADIENT AND THEREFORE VERY LIGHT
PREVAILING WINDS BUT THIS WILL LEAD TO A STRONGER SEA BREEZE
PUSHING WELL INLAND. EXPECT A GREATER AMOUNT OF CU ASSOCIATED WITH
CONVERGENCE ALONG SEA BREEZE BOUNDARY AS IT PUSHES INLAND AND
AROUND WESTERN PERIPHERY OF HIGH AS IT SHIFTS EAST THROUGH LATER
TODAY. TEMPS WILL HOLD BETWEEN 75 AND 80 MOST PLACES THROUGH THE
REMAINDER OF THE AFTERNOON...SLIGHTLY COOLER ALONG BEACHES.

OTHERWISE EXPECT MID TO UPPER RIDGE TO TRY AND BUILD OVERHEAD
WITH PLENTY OF SUBSIDENCE AND DRY AIR BUT IT WILL BE DISRUPTED BY
A COUPLE OF SHORTWAVES MOVING DOWN IN THE NORTHWEST FLOW ALOFT
TONIGHT. THESE SHOULD NOT PRODUCE ANYTHING MORE THAN SOME MID TO
HIGH CLOUDS. THE AIR MASS WILL CONTINUE TO MODIFY IN E-SE RETURN
FLOW AS SFC HIGH SHIFTS FARTHER EAST OVERNIGHT. THIS WILL ALLOW
FOR MODEST MOISTURE RETURN WITH DEWPOINT TEMPS REACHING BACK FROM
LOWER 40S THIS AFTERNOON UP TO THE MID 50S OVERNIGHT. EXPECT TEMPS
TO DROP OFF AS ATMOSPHERE DECOUPLES LATE THIS EVENING WITH TEMPS
DROPPING TO 50S FOR LOWS MOST PLACES. ALSO EXPECT PATCHY TO AREAS
OF FOG AS TEMPS DROP WITH LIGHT TO CALM WINDS AND LIMITED CLOUD
COVER.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 3 PM SUNDAY...SEASONABLE MAY SUNSHINE ON TAP THIS PERIOD
WITH WEAK LOW-LEVEL ONSHORE FLOW AND DRY AIR PERCHED ABOVE 600MB
AND LIGHT WINDS ALOFT. WEAK SHORT-WAVE IMPULSES WILL MEANDER OVER
THE AREA AS NOTED IN H7-H5 VORTICITY FIELDS BUT WITHOUT FANFARE
OTHER THAN MODERATE CUMULUS BUILD-UPS WITH ASSISTANCE FROM MAY
SUN ANGLE AND RESULTING AFTERNOON INSOLATION. MAXIMUMS A FEW DEG
EITHER SIDE OF 80 WARMEST INLAND...AND MINIMUMS IN THE UPPER 50S
TO LOW 60S CLOSER TO THE COAST. TUESDAY LOOKS WARMER OVER THE
INTERIOR AS THE UPPER RIDGE BECOMES SLIGHTLY MORE ESTABLISHED.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 3 PM SUNDAY...THE ENTIRETY OF THE LONG TERM WILL FOCUS ON
WHAT IS EXPECTED TO BECOME A HYBRID/SUB-TROPICAL LOW OFF MEANDERING
OFF THE SOUTHEAST COAST. LARGE AREA OF DISTURBED WEATHER WILL MOVE
OUT OF THE CARIBBEAN AND THEN STRENGTHEN INTO A LOW PRESSURE SYSTEM
WELL OFFSHORE. THIS OCCURS IN A REGION OF VERY WEAK STEERING FLOW IN
THE VICINITY OF A LARGE MID-LEVEL RIDGE ACROSS THE SOUTHEAST...AND
THUS THERE IS VERY LITTLE CONFIDENCE IN WHAT THIS SYSTEM WILL DO
ONCE IT DEVELOPS...AND GUIDANCE IS ALL OVER THE PLACE IN HOW THE LOW
WILL TRACK. HOWEVER...THERE IS INCREASING CONFIDENCE THAT A HYBRID-
LOW WILL DEVELOP...BECOMING WARM CORE AND LIKELY STRENGTHENING
THANKS TO A COMBINATION OF LATENT HEAT RELEASE FROM 80 DEGREE WATERS
IN THE GULF STREAM...BAROCLINIC INSTABILITY DUE TO CHANGE IN WATER
TEMPS NEAR THE COAST...AND GOOD VENTILATION THROUGH DIFFLUENCE
ALOFT. WILL NOT MAKE ANY WHOLESALE CHANGES TO POP/WX IN THE EXTENDED
DUE TO SUCH LOW CONFIDENCE...AND WILL MAINTAIN THE INHERITED POP FOR
THE THU-SUN TIMEFRAME...HIGHEST CHANCE AT THE COAST. STILL...CANNOT
FOCUS ON ANY SPECIFIC DAY BEING THE MOST FAVORABLE FOR PRECIP AS THE
GUIDANCE ENVELOPE IS SO WIDE. ON THE BRIGHT SIDE...TEMPS THROUGH THE
PERIOD SHOULD BE ABOVE CLIMO...ESPECIALLY AWAY FROM THE COAST.

&&

.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
AS OF 00Z...NOT MUCH SYNOPTICALLY DIFFERENT FROM YESTERDAY...WITH
HIGH PRESSURE OFFSHORE GIVING US SOUTHEAST FLOW. THERE IS FOG
POTENTIAL AGAIN OVERNIGHT...MAINLY AFTER 08Z. CRE STANDS THE BEST
CHANCE AGAIN...BUT COULD NOT RULE OUT INLAND FOG EITHER. DO NOT
THINK WE WILL SEE THE LIFR CONDITIONS THAT WE EXPERIENCED LAST
NIGHT. MONDAY...BECOMING VFR AT ALL LOCATIONS WITH CONTINUED
SOUTHEAST FLOW...STRONGEST ALONG THE COAST.

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 715 PM SUNDAY...LATEST OBS SHOW LIGHT...GENERALLY
SOUTHERLY...WINDS WITH SEAS AROUND 2 FT. NO CHANGES NEED TO BE
MADE TO THE FORECAST FOR THE NEAR TERM. PREVIOUS DISCUSSION
FOLLOWS:

HIGH PRESSURE OVERHEAD THIS AFTERNOON WILL SHIFT FARTHER OFF
SHORE THROUGH TONIGHT. THEREFORE EXPECT VERY LIGHT WINDS TODAY
SHIFTING AROUND TO AN ON SHORE RETURN FLOW AS HIGH MOVES EAST
WHILE EXTENDING BACK WEST. EXPECT A DECENT SEA BREEZE TO DEVELOP
WHICH WILL LEAD TO SOME CHOPPY SEAS IN THE AFTERNOON INTO THE
EVENING WITH WINDS NEARSHORE BECOMING E-SE TO S-SE AT 10 KT...AND
UP TO 10 TO 15 KT AND GUSTY AT THE HEIGHT OF THE SEA BREEZE.

SIGNIFICANT SEAS WILL RUN AROUND 2 TO 4 FT WITH A VERY SLOW
DECLINE THROUGH TONIGHT AS SEA BREEZE CUTS OFF AND BACKSWELL FROM
THE LOW MOVING OFF INTO THE DISTANT ATLANTIC WATERS BEGINS TO
SLOWLY WANE. OVERALL THE LONGER PERIOD E-NE 9 TO 11 SECOND SWELL
WILL CONTINUE TO DOMINATE THE WATERS WITH ONLY A SPIKE IN WIND
WAVES THROUGH LATE THIS AFTN DUE TO THE SEA BREEZE.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 PM SUNDAY...FRIENDLY MARINE ENVIRONMENT EXPECTED THIS
PERIOD AS LIGHT ONSHORE FLOW PREVAILS WITH MINIMAL WAVE ENERGY.
A MODERATE AFTERNOON SEA BREEZE MAY DRIVE ONSHORE GUSTS TO 17 KT
INSHORE ACCOMPANIED BY MODERATE CHOP...OTHERWISE ONSHORE 10 KT
MON/TUE. WITH LIGHT CHOP AND WEAK SWELL DOMINANT WAVE PERIOD OF
7-9 SECONDS EXPECTED...EXCEPT INSHORE DURING THE AFTERNOON THE
CHOP MAY BRIEFLY BECOME THE PRIMARY ENERGY. NO TSTMS OR VSBY
RESTRICTIONS EXPECTED MONDAY OR TUESDAY.

LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 3 PM SUNDAY...ALL EYES WILL BE ON A HYBRID-TYPE LOW
PRESSURE SYSTEM DEVELOPING WELL OFF THE SOUTHEAST COAST. THIS LOW
IS EXPECTED TO BEGIN FORMATION WEDNESDAY...AND THEN STRENGTHEN
SLOWLY WHILE MEANDERING IN WEAK STEERING FLOW. STILL MUCH
UNCERTAINTY REGARDING THIS PORTION OF THE FORECAST...BUT CONSENSUS
AT THIS TIME KEEPS WINDS E/NE THROUGH THE PERIOD WITH SPEEDS
PRIMARILY 10-15 KTS...HIGHER AT TIMES. OF COURSE...THESE COULD
CHANGE SIGNIFICANTLY DEPENDING ON HOW THIS STORM SYSTEM EVOLVES.
PROLONGED E/NE FETCH COMBINED WITH THE ELEVATED WINDS WILL DRIVE
SEAS UP FROM 3-5 FT WEDNESDAY...TO 4-7 FT THU/FRI...AND AN
EXTENDED SCA MAY BE NEEDED FOR MUCH OF THE PERIOD.

&&

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

&&

$$

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



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