-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 200011
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
811 PM EDT SUN MAY 19 2013

.SYNOPSIS...
WESTERN ATLANTIC HIGH PRESSURE WILL RIDGE ACROSS THE FORECAST AREA
FOR THE MAJORITY OF THIS WEEK. A DISTURBANCE ALOFT MOVING ACROSS
THE AREA EARLY IN THE WEEK...WILL MAINTAIN THE THREAT FOR CONVECTION
TONIGHT THROUGH TUESDAY. FOR THE REMAINDER OF THE WEEK...EXPECT A
RETURN BACK TO THE NORMAL DIURNALLY INDUCED CONVECTION THREAT. FOR
LATE THURSDAY AND FRIDAY...A COLD FRONT WILL PUSH ACROSS THE AREA.
IN ITS WAKE...DRY CANADIAN HIGH PRESSURE WILL RIDGE ACROSS THE REGION
DURING THE UPCOMING HOLIDAY WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
-- Changed Discussion --
AS OF 700 PM SUNDAY...VIA LATEST 88D TRENDS...CONVECTIVE ACTIVITY
WEAKENING INLAND AND INCREASING AT THE COAST. IN GENERAL THE ATM
HAS BEEN WORKED OVER INLAND...WHERE-AS ALONG THE COAST...THE ATM
HAS HAD TIME TO RECOVER SOME FROM THE ACTIVITY EARLIER TODAY. POPS
ACROSS THE ENTIRE ILM CWA HAVE BEEN RE-ADJUSTED FOR THIS EVENING TO
ACCOUNT FOR THESE CURRENT TRENDS. QPF HAS ALSO BEEN RE-TOOLED...
MAINLY FOR THE EVENING HOURS. HAVE MAINTAINED THE PREVIOUS
FORECAST WITH POPS PROGGED TO GENERALLY INCREASE AFTER MIDNIGHT
ALONG THE IMMEDIATE COAST AND ADJACENT ATL WATERS...WITH LATEST
18Z MODELS FOLLOWING SUIT. OVERNIGHT MIN TEMPS AND HOURLY
DEWPOINTS HAVE SLIGHTLY BEEN TWEAKED BASED ON CURRENT OBS AND
LATEST MODEL MOS GUIDANCE.

PREVIOUS DISCUSSION...................................
AS OF 300 PM SUNDAY...THROUGH MIDDLE EVENING...SUBSTANTIAL RAINFALL
AMOUNTS OF 1-2 INCHES WILL BE FAVORED ACROSS OUR ZONES WEST OF I-95
WHERE ONE IMPULSE ALOFT EVIDENT IN VAPOR ANIMATIONS MOVING EAST OVER
CENTRAL SC...WILL SERVE AS A CATALYST FOR CONVECTION BY PROVIDING
UPPER SUPPORT THROUGH THE PERIOD OF MAXIMUM DIURNAL SURFACE HEATING.
STEERING FLOW WILL CONTINUE TO GUIDE THE RAIN MAKERS GENERALLY SOUTH
TO NORTH WITH A SLIGHT EASTWARD NUDGE. THE EASTERN 1/3 OF OUR ZONES
HAVE BECOME MORE STABILIZED BY THE DIVERGENCE ASSOCIATED THE SEA
BREEZE CIRCULATION AND A LESS BUOYANT LOW-LEVEL MARINE LAYER...SO
HIGHEST POPS TO PREVAIL INLAND THROUGH MUCH OF THE NIGHT PERIOD.

SCATTERED TO NUMEROUS SHOWERS WITH ISOLATED TSTMS WILL CONTINUE TO
MOVE NNE THROUGH THE AFTERNOON AND OVERNIGHT PERIOD AHEAD OF A MID
LEVEL TROUGH...SHIFTING CONVECTIVE FOCUS GRADUALLY EAST THROUGH
THE LATE NIGHT. THINK DIURNAL SURFACE COOLING AFTER EVENING MAY
DECREASE CONVECTIVE INTENSITY OVERALL...BUT WITH ADEQUATE UPPER
SUPPORT AND PWAT VALUES APPROACHING 1.75 INCHES INTO THE PRE-DAWN
HOURS OF MONDAY...THE POTENTIAL FOR HEAVY SHOWERS AND ISOLATED TSTMS
WILL PREVAIL OVERNIGHT. AS THE UPPER TROUGH NEARS THE COASTAL ZONES
BY DAYBREAK MONDAY...STORM MOTION WILL TAKE ON A MORE WEST TO EAST
TRAJECTORY...WITH BEST DYNAMICS ALOFT SHIFTING CLOSER TO THE COAST.
TIMING OF QPF FIELDS BRINGS THE BEST RAINFALL OPPORTUNITY FOR OUR
COASTAL LOCATIONS MAINLY JUST AFTER 12Z MONDAY.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...MAIN FORECAST CHALLENGE WILL BE POPS AND THE
TIMING THEREOF AT LEAST THROUGH THE FIRST DAY...MONDAY. THE MID
LEVEL PATTERN WILL CONSIST OF A WEAK RIDGE EXTENDING INTO THE
TENNESSEE VALLEY/WESTERN NORTH CAROLINA REGION WITH A BROAD
WEAKNESS ALONG THE EAST COAST AT LEAST FROM FLORIDA NORTH TO THE
DELMARVA. PRECIPITABLE WATER VALUES REMAIN ELEVATED MONDAY INTO
MONDAY EVENING NEAR ONE AND THREE QUARTERS OF AN INCH. THE FORCING
WILL BASICALLY CONSIST OF THE WEAK MID LEVEL FORCING...A BROAD
DEFORMATION ZONE IN THE 700-300MB LAYER...AND DIFFERENTIAL HEATING
VIA THE SEA BREEZE AND INTERVALS OF CLOUDS.

INTERESTING TO LOOK AT THE CURRENT MESOSCALE CONVECTIVE SYSTEMS WEST
OF OUR AREA AND THE DEFORMATION. THESE APPEAR TO BE THE PRODUCT OF
THIS BROAD ZONE. HOWEVER THIS AREA OF FORCING...WHILE STILL PRESENT
IN A WEAKER STATE MONDAY AND OVER OUR AREA...MOVES LITTLE AND DO NOT
ANTICIPATE AS MUCH ORGANIZED CONFECTION...MORESO OF WHAT WE ARE
SEEING TODAY. MORE OF A SOUTHWEST FLOW DEVELOPS TUESDAY WITH PW
VALUES DROPPING SOMEWHAT AND THIS IS REFLECTED IN LOWER POP VALUES.

FOR TEMPERATURES...LOW CONFIDENCE FORECAST BUT I FOLLOWED A
CONSISTENT TREND OF LOWER VALUES MET NUMBERS MONDAY VIA HIGHER POPS
AND WARMER NUMBERS TUESDAY...MAV NUMBERS.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 300 PM SUNDAY...WEDNESDAY SHOULD BE THE LAST DAY WITH THE
ABSENCE OF ANY SYNOPTIC SCALE ASCENT AS WEST ATLANTIC SURFACE AND
UPPER RIDGE HOLD ON. THE LATTER WILL BE WEAKENING HOWEVER AND LARGE
SCALE WEAK FORCING MAY KICK IN AS EARLY AS WEDNESDAY NIGHT. THE
AFTERNOON HOURS WILL STILL BE SUSCEPTIBLE TO ISOLATED COVERAGE OF
CONVECTION BORNE OF MESOSCALE BOUNDARIES ESPECIALLY WITH
TEMPERATURES ON THE WARM SIDE OF CLIMO...YIELDING EXTRA INSTABILITY.
THURSDAY AND FRIDAY MAY TURN ACTIVE WITH UPPER TROUGH AND SURFACE
COLD FRONT BOTH IMPINGING UPON THE REGION FROM THE NW. THE SPEED
AND AMPLITUDE OF THE TROUGH AND ENSUING COOLER/DRIER AIR IS NOT
AGREED UPON BY MODEL GUIDANCE. THE SLOWER AND LESS AMPLIFIED 00Z
EC SEEMS AT ODDS WITH THE MORE AGGRESSIVE GFS/GEM. THE QUICKER
SOLUTIONS OF CONTINUITY HAVE BEEN PRESERVED...IMPLYING THAT SOME
CONSIDERABLY DRIER AIR WILL WORKING OVER THE WEEKEND.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
AS OF 00Z...PERIODS OF MVFR/IFR POSSIBLE OVERNIGHT...ESPECIALLY
INLAND...DUE TO LOW CIGS AND AREAS OF FOG. OTHERWISE EXPECT VFR
WITH PERIODS OF MVFR/IFR POSSIBLE ON SUNDAY WITH ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS.

SCT/BKN LOW/MID/HIGH LEVEL CLOUDS AS WELL AS SHOWERS ARE SPREAD
ACROSS THE AREA THIS EVENING. LATEST OBS ALSO DEPICTING SOME
AREAS OF FOG...BUT CURRENTLY NOT AFFECTING ANY OF THE TERMINALS.
EXPECT SOUTH WINDS AOB 8 KTS AND LINGERING ISOLATED SHOWERS
THROUGH THE OVERNIGHT HOURS...WITH LOW CIGS CREATING MVFR/BRIEF
IFR CONDITIONS POSSIBLE GIVEN FCST SOUNDINGS AND TIME-HEIGHT
ANALYSIS. ALSO CANNOT RULE OUT FOG INLAND LATE OVERNIGHT INTO THE
EARLY MORNING HOURS...WHICH MAY CREATE MVFR/BRIEF IFR. AFTER
DAYBREAK...ANY LINGERING FOG WILL DISSIPATE AND CIGS WILL
GRADUALLY LIFT GIVING WAY TO VFR AREA-WIDE. SOUTHWEST WINDS WILL
PREVAIL AOB 10 KTS WITH GUSTS UP TO 18 KTS ALONG THE COAST LATER
IN THE DAY. CHANCE FOR ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS THROUGHOUT THE DAY.

EXTENDED OUTLOOK...AFTN SHOWERS/TSTMS POSSIBLE MONDAY AND
TUESDAY. OTHERWISE PREVAILING VFR.



AS OF 18Z...EXPECT TO SEE
SCATTERED SHOWERS AND STORMS TO CONTINUE THE PATTERN OF
REDEVELOPMENT AND DISSIPATION DURING THE TAF PERIOD AS WE HAVE
SEEN DURING THE PREVIOUS 24 HOURS. INITIALLY...THE GREATEST
POTENTIAL FOR ADDITIONAL CONVECTION WILL BE OVER SOUTHERN AND
WESTERN AREAS TODAY WITH A SHIFT EAST AND NORTH TONIGHT INTO
MONDAY. THE EXACT TIMING THAT EACH TERMINAL WILL BE AFFECTED
DURING THE NEXT 24 HOURS IS SOMEWHAT UP TO CHANCE SO PILOTS SHOULD
BE PREPARED TO DEAL WITH THE ATTENDANT MVFR OR BRIEF IFR CIGS AND
VSBYS AT ALMOST ANY TIME DURING THE NEXT 24 HOURS. OUTSIDE
CONVECTION EXPECT S WINDS OF 5 TO 10 KT WITH SLIGHTLY HIGHER WINDS
POSSIBLE NEARER THE COAST THIS AFTERNOON.

EXTENDED OUTLOOK...AFTN SHOWERS/TSTMS POSSIBLE AGAIN MONDAY AND
TUESDAY. OTHERWISE PREVAILING VFR.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
NEAR TERM /THROUGH TONIGHT/...
AS OF 700 PM SUNDAY...LATEST COASTAL AND MARITIME OBS INDICATE
WINDS NEED TWEAKING SLIGHTLY LOWER ACROSS THE NEAR SHORE
WATERS... BASICALLY UP TO 10 NM OUT FROM THE COAST DURING THE
EVENING HOURS. OVERALL LOOKING AT 170-190 DEGREE WINDS AT 5 TO 10
KT NEAR SHORE...10-15 KT ELSEWHERE...BECOMING 10-15 KT THRU OUT
AFTER MIDNIGHT. SIGNIFICANT SEAS 2 TO 3 FT...WITH 4 FOOTERS
POSSIBLE ACROSS THE OUTER WATERS 15-20 NM OUT. A 1 TO 2 FOOT
EASTERLY PSEUDO SWELL AT 8 TO 9 SECOND PERIODS...AND WILL MESH
WITH LOCALLY GENERATED SOUTHERLY WIND WAVES AT 4 TO 5 SECOND
PERIODS.

PREVIOUS DISCUSSION....................................
AS OF 300 PM SUNDAY...MODERATE SOUTH WINDS WILL PREVAIL ALTHOUGH
THEY HAVE BEEN A BIT LIGHTER THAN FORECAST...ASIDE FROM LOCAL
GUSTY INSHORE DUE TO THE SEA BREEZE CIRCULATION. THUS THINK SEAS
WILL GENERALLY HOLD IN A 2-3 FOOT RANGE MOST WATERS...POSSIBLY
NEAR 4 FEET LATE TONIGHT OVER THE OUTER WATERS WHERE PERSISTENCE
OF SSE WINDS PREVAIL. SEAS PF 2-4 FEET...HIGHEST OFFSHORE...WILL
BE MADE UP OF 2-3 FOOT SSE WAVES EVERY 5-6 SECONDS...AND 1-2 FOOT
ESE WAVES EVERY 8-9 SECONDS. MARINERS ARE ENCOURAGED TO GET A
RADAR UPDATE BEFORE HEADING OUT SINCE A FEW STRONG TSTMS COULD DOT
THE WATERS LATER TONIGHT INTO MONDAY MORNING. WINDS AND SEAS WILL
BE LOCALLY HIGHER IN AND NEAR TSTMS.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...SURFACE PATTERN CHANGES LITTLE THROUGH THE
PERIOD WITH IF ANYTHING...A SLIGHT TURN IN THE WINDS TOWARD THE
SOUTHWEST TUESDAY. DIRECTION SHOULD REMAIN STRAIGHT SOUTHERLY
MONDAY. OVERALL WINDS WILL CONTINUE TO DISPLAY SUMMERTIME SPEEDS
IN A 10-15 KNOT RANGE. SEAS WILL ALSO DISPLAY LITTLE IN THE WAY
OF VARIABILITY WITH 2-4 FEET AS PERIODS REMAIN DOMINATED BY WIND
WAVES.


LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 PM SUNDAY...SOUTH TO SOUTHWESTERLY FLOW THROUGH THE
PERIOD WITH BERMUDA HIGH PRESSURE BEING THE MAIN PLAYER AT LEAST
INITIALLY. THE INCREASED DURATION OF FETCH WILL ALLOW FOR SOME
LONGER PERIOD SWELL ENERGY TO BEGIN MOVING INTO THE SOUTHEASTERN
U.S. AS A RESULT THERE SHOULD BE A DECREASE IN THE OVERALL WAVE
PERIOD WHILE SIGNIFICANT WAVE HEIGHT IS ON THE RISE. THERE COULD
EVEN BE SOME SCEC-WORTHY 5 FT SEAS ALONG THE OUTER EDGES OF THE
FCST ZONES BY THURSDAY. APPROACHING COLD FRONT ON FRIDAY COULD
VEER THE WIND SLIGHTLY. THIS BOUNDARY MAY BE COMING THROUGH AS
EARLY AS FRIDAY NIGHT BUT A SLOWER SOLUTION SEEMS LIKELY IN
FUTURE MODEL RUNS.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...SHK
NEAR TERM...DCH/MJC
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...SGL