-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 210054
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
854 PM EDT MON MAY 20 2013

.SYNOPSIS...
A DISTURBANCE ALOFT MOVING ACROSS THE AREA WILL MAINTAIN SHOWERS AND
THUNDERSTORMS THROUGH TUESDAY. DRIER AND WARMER WEATHER IS EXPECTED
MID WEEK. A COLD FRONT IS EXPECTED TO APPROACH AND CROSS THE REGION
ON FRIDAY...BRINGING DRIER AND SLIGHTLY COOLER WEATHER INTO THE NEXT
WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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AS OF 745 PM MONDAY...CONVECTIVE ACTIVITY HAS WANED ACROSS THE FA
EARLY THIS EVENING...NEARLY IDENTICAL TO WHAT TRANSPIRED SUNDAY
EVENING. THE ATM ACROSS THE FA HAS BEEN ONCE AGAIN TAXED AND
BECOME SOMEWHAT STABLE AND WILL NEED SOME TIME TO DE-STABILIZE.
LIKE LAST EVENING AND OVERNIGHT...THE DAYS INSOLATION WILL NOT BE
AVAILABLE TO AID THE DESTABILIZATION PROCESS. WILL HAVE TO
RELY...LIKE LAST NIGHT...DYNAMICS FROM WEAK PVA ALOFT AND IN
ADDITION...THE SLIGHTLY COLDER TEMPS ALOFT TO REACH THE FA FROM
THE SW-W DIRECTION. LATEST CHS 00Z RAOB INDICATES SUB -10 C AT
500MB...WITH PWS ACROSS THE FA FROM 1.5 TO 1.7 INCHES. STORM
MOTIONS REMAIN SLOW 10 KT OR LESS WHICH WILL RESULT IN SUFFIXING
THE CONVECTION WITH HEAVY RAIN POSSIBLE. THE COASTAL PORTIONS OF
THE ILM CWA WILL HAVE THE HIGHEST POPS ILLUSTRATED...MAINLY
TO OCCUR DURING THE PRE-DAWN HRS INTO DAYLIGHT MORNING TUESDAY.
MIN TEMP FORECAST TWEAKED ACROSS THE FA BUT WILL REMAIN IN THE MID
TO UPPER 60S RANGE PREVIOUSLY FORECAST.

PREVIOUS DISCUSSION...............................................
AS OF 300 PM MONDAY...SPC MESOANALYSIS PAGE SHOWS THE HEAVIEST
CONVECTIVE RAINFALL IN ENCOMPASSED WITHIN A DEEP POCKET OF MOISTURE
STREWN ACROSS THE CENTRAL AND EASTERN CAROLINAS...WHERE PRECIPITABLE
WATERS WERE ESTIMATED AROUND 1.8 INCHES THIS AFTERNOON. WATER VAPOR
ANIMATIONS DEPICT A COMPLEX SET OF SWIRLS EMBEDDED WITHIN A WEAK
UPPER TROUGH FROM VIRGINIA TO NORTHERN FLORIDA. DIURNAL COOLING
INTO EVENING SHOULD REMOVE SOME INTENSITY OF CONVECTION...BUT GOOD
UPPER SUPPORT AND A MOISTURE RICH ENVIRONMENT SHOULD ALLOW FOR A
FEW BIG RAIN-MAKERS TO PERSIST THROUGH EVENING. THE OVERNIGHT
PERIOD WILL LIKELY SEE RE-DEVELOPMENT OVER THE WATERS AS LOW-LEVEL
BUOYANCY INCREASES. CIRCULATION AROUND BERMUDA HIGH PRESSURE WILL
HELP GUIDE OCEAN ACTIVITY ONTO THE COAST...AND THIS PROCESS MAY
LEAD TO NOTABLE RAIN AMOUNTS OF 1/2-1 INCH FOR THE COASTAL ZONES
OVERNIGHT. WITH THIS IN MIND WILL KEEP HIGH SCATTERED TO LIKELY
POP VALUES IN PLACE OVERNIGHT INTO DAYBREAK MONDAY...GRADUALLY
SHIFTING FOCUS INLAND...TO THE COAST IN THE NEAR TERM PERIOD.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...FORECAST MODELS ARE CONSISTENT IN SHOWING
THE MID LEVEL PATTERN TRANSITIONING FROM WHAT SEEMS LIKE A NEVER
ENDING TROUGH/WEAKNESS TO MORE OF A SOUTHWESTERLY FLOW. THIS IN
RESPONSE TO THE MASSIVE MID LEVEL LOW FINALLY OPENING UP ACROSS
THE NORTHERN PLAINS AND GETTING KICKED OUT.

AT THE SURFACE...BERMUDA HIGH PRESSURE WILL REMAIN THE MAIN PLAYER
ALTHOUGH THIS HAS LITTLE IMPACT OR CHANGE ON PREVAILING CONDITIONS
AS THIS HAS BEEN SECONDARY THE PAST FEW DAYS. POPS REMAIN ON A
DIURNAL CYCLE ALTHOUGH LOWER THROUGH THE PERIOD AS THE MID LEVEL
CATALYST IS ALL BUT REMOVED. HAVE OPTED FOR THE WARMER MAV NUMBERS
FOR TEMPERATURES THROUGH THE PERIOD.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 PM MONDAY...ONE LAST DAY OF WARM AND HUMID CONDITIONS ON
THURSDAY AS UPPER TROUGH AND SURFACE COLD FRONT BEAR DOWN ON THE
REGION FROM THE NW. SOMEWHAT SURPRISINGLY MODELS ARE GRAVITATING
TOWARDS A QUICKER SOLUTION AND THE FRONT MAY PUSH THROUGH TUESDAY
NIGHT. AHEAD OF IT SW FLOW AND HEIGHT FALLS SHOULD YIELD BETTER THAN
AVERAGE COVERAGE OF CONVECTION AND WITH A LARGELY PINNED SEABREEZE
THERE MAY BE NO PREFERRED LOCATION FOR MEASURABLE RAINFALL ESP THIS
FAR OUT IN TIME. SYSTEM WILL MOVE A LITTLE BIT SLOWLY OWING TO THE
STRENGTH OF THE DOWNSTREAM RIDGING AND RAIN CHANCES MAY LINGER INTO
FRIDAY ESPECIALLY ALONG THE COAST. MODEST COOLING AND STRONG DRYING
WILL THEN FOLLOW FOR THE WEEKEND AND SOME VERY COMFORTABLE AND
PLEASANT WEATHER APPEARS TO BE ON TAP. DAYTIME DEVIATIONS FROM CLIMO
TEMPS SHOULD BE RATHER SMALL BUT THE NIGHTS MAY TURN COOLISH DUE TO
THE DRYING. THE POST-FRONTAL HIGH MAY MOVE OFF THE COAST ON MONDAY
ALLOWING FOR AN UPTICK IN THE DEWPOINTS.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
AS OF 00Z...SLIGHT CHANCE OF ISOLATED SHOWERS OVERNIGHT WITH PERIODS
OF MVFR/IFR POSSIBLE DUE TO LOWERED CIGS/AREAS OF FOG
INLAND. OTHERWISE EXPECT VFR WITH PERIODS OF MVFR/IFR POSSIBLE ON
TUESDAY WITH ISOLATED TO SCATTERED SHOWERS AND A POSSIBLE
THUNDERSTORM.

ACTIVITY HAS QUIETED DOWN OVER THE PAST FEW HOURS...WITH ONLY AN
ISOLATED SHOWER OR TWO DEPICTED ON LATEST RADAR IMAGERY. MAINLY VFR
PREVAILS THIS EVENING WITH LIGHT SOUTH WINDS...WITH AREAS OF LOW
CIGS INLAND CREATING MVFR/IFR. GIVEN RAINFALL FROM TODAY...ALONG
WITH LATEST FCST SOUNDING ANALYSIS...COULD FORESEE FOG/LOW LEVEL
STRATUS BECOMING AN ISSUE LATE OVERNIGHT AND INTO THE EARLY
MORNING HOURS...MAINLY AT THE INLAND SITES. WOULD NOT COMPLETELY
RULE OUT ISOLATED SHOWERS LATE OVERNIGHT AS WELL. FOR
SUNDAY...SCT/BKN/OVC CLOUD COVERAGE WILL CONTINUE WITH SOUTH-SOUTHWEST
WINDS AOB 10 KTS. HAVE KEPT IN VCSH AT ALL SITES GIVEN SLIGHT
CHANCE FOR ISOLATED TO SCATTERED SHOWERS...AND THE POSSIBILITY OF
AN ISOLATED THUNDERSTORM DURING THE DAY.

EXTENDED OUTLOOK...SCATTERED SHOWERS/TSTMS WITH TEMPO MVFR ON
TUESDAY. CHANCE OF SHOWERS THURSDAY THROUGH EARLY FRIDAY.
OTHERWISE EXPECT VFR.

&&

.MARINE...
-- Changed Discussion --
NEAR TERM /THROUGH TONIGHT/...
AS OF 810 PM MONDAY...SSE-SSW WINDS TO REMAIN 10 TO OCCASIONALLY
15 KT OVERNIGHT...IN RESPONSE TO RIDGING FROM THE WESTERN
ATLANTIC HIGH. SOUTH OF THE SFC RIDGING...ESE-SSE FLOW WELL
OFFSHORE ACROSS A DECENT FETCH LEADING UP TO THE SE U.S.
COAST. THIS WILL RESULT IN AN EVOLVING SE GROUND SWELL AT 2 TO 4
FT EXHIBITING 7 TO 8 SECOND PERIODS JUST PRIOR TO ENTERING THE ILM
COASTAL WATERS. COMBINED WITH 3 TO 5 SECOND PERIOD LOCALLY
PRODUCED WIND DRIVEN WAVES...SIGNIFICANT SEAS WILL RUN A SOLID 3
TO 4 FT...WITH 5 FOOTERS POSSIBLE ACROSS THE OUTER WATERS OFF CAPE
FEAR. OVERALL WIND AND SIG SEAS FORECAST ON TRACK. ONLY UPDATE WAS
TO RESTRUCTURE POPS ACROSS THE COASTAL WATERS TO ACCOUNT FOR THE
DIMINISHED CONVECTION THIS EVENING...AND INCREASED COVERAGE TOWARD
DAYBREAK.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...BERMUDA HIGH PRESSURE REMAINS THE MAIN FEATURE
FOR THE COASTAL WATERS WITH A SOUTHERLY FLOW EXPECTED TO CONTINUE
THROUGH THE PERIOD. SPEEDS WILL CONTINUE IN A 10-15 KNOT RANGE
WITH A SLIGHT INCREASE CLOSER TO THE COAST EACH LATE MORNING AND
AFTERNOON WITH THE SEA BREEZE. THE LATEST RUN OF SWAN REMAINS
CONSISTENT WITH 2-4 FOOT SEAS.

LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 300 PM MONDAY...COAST WILL LIE BETWEEN STRONG HIGH PRESSURE
ACROSS THE WEST-CENTRAL ATLANTIC AND APPROACHING COLD FRONT TO THE
NW. THE LATTER WILL BE DISPLACED EASTWARD OF THE MORE TYPICAL
BERMUDA HIGH POSITION WHICH WILL ACT TO EASE THE GRADIENT OTHERWISE
EXPECTED GIVEN SUCH A LARGE ANTICYCLONE. THE RESULTING SWELL ENERGY
COULD BRING SOME SCEC-WORTHY 5 FT SEAS TO PART OF THE AREA MAINLY
NORTHERN ZONES. COLD FRONT NOW APPEARS FASTER THAN PREVIOUSLY
THOUGHT AND SHOULD YIELD VEERING WINDS BY FRIDAY MORNING WITH A TURN
TO OFFSHORE. THE OFFSHORE FETCH AND SWELL DISRUPTION WILL LEAD TO
LOWER SEAS ON FRIDAY BUT THEN THE ENSUING PUSH OF DRY HIGH PRESSURE
COULD TIGHTEN THE GRADIENT AGAIN TO WHERE HEADLINES TOUGH TO RULE
OUT.
-- 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