000
FXUS62 KILM 191913
AFDILM

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

.SYNOPSIS...
UNSETTLED CONDITIONS WILL PERSIST FOR MUCH OF THE WEEK. A COLD
FRONT WILL MOVE ACROSS THE AREA THIS WEEKEND BRINGING COOLER AND
DRIER CONDITIONS.

&&

.NEAR TERM /THROUGH TONIGHT/...
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.


&&

.SHORT TERM /MONDAY 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 /19Z SUNDAY THROUGH FRIDAY/...
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.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
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.

&&

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

&&

$$
SYNOPSIS...SHK
NEAR TERM...MJC
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...RAN