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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 182306
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
706 PM EDT SAT MAY 18 2013

.SYNOPSIS...
RAIN CHANCES WILL INCREASE THE NEXT COUPLE OF DAYS AS WEAK LOW
PRESSURE ALOFT DRIFTS ACROSS THE CAROLINAS...WITH DAY AND NIGHT
TIME TEMPERATURES RUNNING NEAR NORMAL FOR MIDDLE MAY. BERMUDA
HIGH PRESSURE WILL BUILD TOWARD THE EAST COAST MID THROUGH LATE
WEEK...BRINGING A DRYING AND WARMING TREND.

&&

.NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --
AS OF 615 PM SATURDAY...2 AREAS OF CONVECTION NOTED BY THE KLTX
88D. OVERALL...SOMEWHAT BETTER ORGANIZED CONVECTION IS AND WILL
AFFECT THE FA THIS EVENING...COMPARED TO WHAT OCCURRED DURING THE
PAST SEVERAL DAYS. FIRST AREA OF CONVECTION CONSISTS OF A BROKEN
LINE OF N TO S ORIENTED ACTIVITY SPEWED ACROSS THE WESTERNMOST
PORTIONS OF THE ILM CWA. THIS CONVECTION WILL MAKE SOME HEADWAY
TO THE EAST THIS EVENING...BUT LIKELY WEAKEN AND/OR DISSIPATE AS IT
MOVES THROUGH THE SEA BREEZE AND INTO A SFC BASED MARINE STABLE
AIR MASS. THIS PCPN ACTIVITY IS ALSO BEING AIDED BY
FORCING/DYNAMICS FROM A MID-LEVEL VORT ALOFT...THAT WAS ONCE
ASSOCIATED WITH THE CLOSED UPPER LOW THAT AFFECTED THE SOUTHERN
U.S. DURING THE PAST MID-WEEK PERIOD. POPS WILL PEAK EARLY THIS
EVENING THEN TAILOR THEM BACK TO ISOLATED TO CHANCE FOR THE
OVERNIGHT PERIOD DUE TO THE LACK OF THE DAYS INSOLATION. THE
IMMEDIATE COAST MAY INEVITABLY NOT OBSERVE MUCH IF ANY PCPN FROM
THIS CONVECTION...ESPECIALLY ACROSS THE ILM NC COAST.

THE 2ND AREA OR CLUSTER OF THUNDERSTORMS LIES ACROSS EASTERN NC 1
TO 2 COUNTIES NE OF THE ILM CWA...WITH MOVEMENT TO THE NE AWAY
FROM THE ILM CWA. THIS ACTIVITY IS MAINLY ASSOCIATED WITH A SFC
FRONTAL BOUNDARY THAT IS SLOWLY LIFTING TO THE NORTH. THERE IS
SOME WEAK FORCING ALOFT FROM THE EARLIER MENTIONED VORT. HOWEVER
...MODELS DO NOT ILLUSTRATE THIS CONVECTION BACK-FILLING ACROSS
THE ILM NC COUNTIES...AND THUS WILL MAINLY CONCENTRATE ON THE 1ST
AREA OF PCPN DISCUSSED EARLIER.

PLENTY OF CLOUDINESS ACROSS THE FA TONIGHT...WHICH INCLUDES
A RATHER THICK VEIL OF CONVECTIVE DEBRIS CLOUDS. THIS WILL LIKELY
HINDER ANY WIDESPREAD/AREAS OF RADIATIONAL FOG DEVELOPMENT...EVEN
ACROSS AREAS RECEIVING RAINFALL TODAY. AT THIS POINT HAVE KEPT
LITTLE IN THE WAY OF FOG DEVELOPMENT. NO TWEAKING TO THE CURRENT
MIN TEMP FORECAST.

PREVIOUS DISCUSSION.............................................
AS OF 3 PM SATURDAY...SLOW MOVING AND DIFFUSE MID LEVEL TROUGH
WILL BEGIN TO IMPACT THE AREA IN A MORE SIGNIFICANT MANNER THIS
AFTERNOON AND EVENING. MOST OF THE HIGH RESOLUTION GUIDANCE AS
WELL AS THE SREF IS AGGRESSIVE ON QPF ACROSS THE WESTERN ZONES BY
0000 UTC AND HAVE RAISED POPS TO LIKELY IN THESE AREAS. THE COAST
SHOULD REMAIN RELATIVELY FREE OF ACTIVITY AS THE MARINE INFLUENCE
AND THE DISPLACEMENT FROM THE BETTER MID LEVEL FORCING TAKES ITS
TOLL. THERE REMAINS A DEFINITE CONVECTIVE NATURE TO THE ACTIVITY
SO I HAVE INCREMENTALLY LOWERED POPS FOR THE OVERNIGHT HOURS. THE
LACK OF THUNDER PROBABLY WARRANTS A CHANGE IN WEATHER TYPE WITH
ONLY ISOLATED THUNDER BEING MORE APPROPRIATE.

WITH ALL THE MOISTURE AND NO WEAK FRONTS AROUND TO DISTORT OVERNIGHT
LOWS...SLIGHTLY WARMER VALUES THAN MOS IS ADVERTISING APPEARS TO BE
THE BEST STRATEGY.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...BATCHES OF SHORT-WAVE ENERGY EVIDENT IN
VAPOR ANIMATIONS TWISTING AND CURLING WELL UPSTREAM OVER THE MID
MISSISSIPPI VALLEY WILL APPROACH AND MOVE ACROSS THE CAROLINAS
SUNDAY AND MONDAY. COLUMN MOISTURE/PWAT VALUES WILL INCREASE AND
WE MAY SEE A FEW DEGREES OF H7 COOLING AS THESE DISTURBANCES MOVE
ACROSS THE AREA. THESE SUBTLE FEATURES OF SLIGHT COOLING ALOFT AND
INCREASING MID-LEVEL MOISTURE MAKE A LARGER DIFFERENCE THIS TIME
OF YEAR WHEN CONVECTION BREWS. WILL MAINTAIN HIGH SCATTERED TO
LIKELY POP VALUES SUNDAY INTO MONDAY GIVEN THESE ANTICIPATED
INGREDIENTS. CONSIDERABLE CLOUDINESS WILL TEMPER MAX TEMPS IN THE
LOW 80S MOST LOCATIONS BOTH SUNDAY AND MONDAY...WHILE KEEPING
NIGHT TIME READINGS VERY MILD. AN H7 COLD FRONT WILL BRING A
WIND-SHIFT AND DRYING ALOFT LATE MONDAY AND HAVE TAPERED POP VALUES
INTO VERY EARLY TUESDAY. EXPECTED RAIN AMOUNTS/QPF BOTH DAYS ADDS UP
TO A 1/2 TO 1 INCH ALONG AND NEAR THE COAST...AND POTENTIALLY 1-2
INCHES OVER OUR WESTERN ZONES AND FAR INTERIOR FOR THE PERIOD SUNDAY
AND MONDAY.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
AS OF 3 PM SATURDAY...BROAD UPPER RIDGING IN PLACE ON TUESDAY AS
WILL BE WEST ATLANTIC SURFACE HIGH PRESSURE. MAIN POINT OF
UNCERTAINTY REGARDING MID LEVEL SHORTWAVE/PRONOUNCED SHEAR AXIS.
SOME GUIDANCE HAS IT ALREADY OFFSHORE FOR WHAT SHOULD BE A RATHER
QUIET AFTERNOON WITH NEAR SEASONABLE TEMPS WHILE OTHERS HAVE IT
ALONG THE COAST FOR SLIGHTLY MORE ACTIVE AFTERNOON OF CONVECTION.
GIVEN HOW WEAK THE FLOW IS WILL SHOW LOW END CHANCE POPS. WITH THIS
FEATURE OUT OF THE PICTURE WEDNESDAY EXPECT A FURTHER WARMUP AND
MERELY ISOLATED CONVECTION ALONG BOUNDARIES LIKE THE SEA BREEZE AND
OUTFLOW FROM ANY ACTIVITY FROM THE PRIOR AFTERNOON. A VERY GRADUAL
UPTICK IN MID LEVEL SWRLY FLOW EXPECTED THURSDAY AHEAD OF TROUGHINESS
STRENGTHENING OVER OH/UPPER MS VALLEYS. THURSDAY THUS BEGINS AN
UPWARD TREND IN CONVECTIVE COVERAGE AS MOISTURE MAY DEEPEN. THE
ACTUAL CYCLONIC FLOW ASSOC WITH THE TROUGH WILL OVERSPREAD THE
REGION THURSDAY NIGHT INTO FRIDAY FURTHER BOLSTERING RAIN CHANCES
AND TEMPERING DAYTIME HIGHS BACK TOWARDS CLIMO.
-- End Changed Discussion --

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
AS OF 18Z...IN GENERAL...EXPECT VFR THROUGH MUCH OF THE PERIOD.
HOWEVER...SCATTERED SHOWERS AND STORMS SHOULD DEVELOP THIS AFTERNOON
AND IMPACT THE INLAND TERMINALS DIRECTLY AND AFFECT THE COASTAL
TERMINALS WITH DEBRIS CLOUDS. SHOWERS AND STORMS...DEBRIS CLOUDS AND
THE PERIOD FOR ABOUT 3 HOURS AFTER SUNRISE SUNDAY MAY RESULT IN
BRIEF PERIODS OF MVFR CONDITIONS AT ALL TERMINALS WITH THE GREATEST
POTENTIAL AT LBT/FLO.  LINGERING CLOUDS AND THE PROXIMITY OF THE
UPPER LEVEL ENERGY TRIGGERING THE STORMS SHOULD PRECLUDE THE
DEVELOPMENT OF SIGNIFICANT FOG TONIGHT.  OUTSIDE STORMS...S TO SW
WINDS OF 5 TO 10 KT ARE EXPECTED DURING DAYLIGHT HOURS THROUGH THE
PERIOD.

EXTENDED OUTLOOK...AFTN SHOWERS/TSTMS POSSIBLE THROUGH MONDAY.
OTHERWISE VFR.

&&

.MARINE...
-- Changed Discussion --
NEAR TERM /THROUGH TONIGHT/...
AS OF 635 PM SATURDAY...ONLY MAJOR CHANGE WAS TO CUT BACK ON THE
POPS RELATED TO THE CONVECTION MOVING OFF THE MAINLAND INTO THE
ILM COASTAL WATERS. RATHER THICK SFC BASED STABLE MARINE LAYER
CONTINUES TO HAVE A NEGATIVE IMPACT ON CONVECTION DEVELOPMENT OR
SUSTAINABILITY AFTER MOVING OFF THE MAINLAND. THIS ALSO CAN BE
SEEN OVER LAND WHEN THE SEA BREEZE PUSHES INLAND FOLLOWED BY A
SFC BASED STABLE MARINE LAYER. THE CONVECTION THAT PUSHES THROUGH
THE SEA BREEZE AND INTO THIS STABLE MARINE LAYER...NOT AS THICK
COMPARED TO THE SOURCE REGION...STILL WEAKENS AND/OR DISSIPATES
BUT JUST NOT AS POETIC WHEN ACTIVITY QUICKLY DISSIPATES AFTER
MOVING OFF THE MAINLAND. LATEST WINDS AND SIG SEAS LOOK AOK WITH
ONLY VERY MINOR TWEAKING NEEDED.

PREVIOUS DISCUSSION.............................................
AS OF 3 PM SATURDAY...THE ONLY SURFACE FEATURE TO IMPACT THE
COASTAL WATERS IS THE SEA BREEZE AND THIS IS TYPICAL OF A
SUMMERTIME PATTERN. OTHERWISE...LOW LEVEL WIND PROFILES...THROUGH
850MB...SHOW ONLY A MARGINAL INCREASE OVERNIGHT TO ABOUT 16
KNOTS...UP FROM ABOUT TEN KNOTS. THIS WILL WARRANT AN INCREASE IN
THE FORECAST TO A RANGE OF 10-15 KNOTS FROM THE SOUTH. SIGNIFICANT
SEAS WILL SEE AN INCREASE FROM AROUND TWO FEET TO 2-3 FEET.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...LESS THAN IDEAL MARINE CONDITIONS EXPECTED
SUNDAY AND MONDAY BUT NO HEADLINES OR CAUTIONARY STATEMENTS ARE
EXPECTED AT THIS TIME. SW WINDS OF 15-20 KT AND 4 FT SEAS WILL
MARK A GOOD PORTION OF THE MARINE FORECAST SUNDAY THROUGH MONDAY
AS BERMUDA HIGH PRESSURE BUILDS WEST TOWARD THE COAST AND LOWER
PRESSURE INLAND INTERACT. SEAS WILL BE COMPOSED OF GROWING S WAVES
WITH PERIODS AROUND 6 SECONDS AND LOW-AMPLITUDE ESE SWELL WAVES.
MARINERS SHOULD CONSIDER GETTING A FIX ON RADAR TRENDS BEFORE
HEADING OUT SINCE TSTMS MAY DOT THE WATERS...FAVORED MOSTLY LATE
SUNDAY INTO MONDAY. WINDS AND WAVES WILL BE LOCALLY HIGHER IN AND
NEAR TSTMS.

LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 3 PM SATURDAY...SOUTHWESTERLY FLOW SHOULD PERVADE THE
ENTIRE PERIOD AS HIGH PRESSURE REMAINS NEARLY STATIONARY ACROSS
THE WESTERN ATLANTIC. THE FLOW MAY INCREASE TOWARDS THE END OF THE
PERIOD AS RIDGE AXIS INTO THE CAROLINAS DEVELOPS AND MOVES TO THE
NORTH. THIS COULD ALSO STEER JUST ENOUGH SWELL ENERGY INTO THE
REGION TO BUILD SEAS A FOOT OR TWO.
-- End Changed Discussion --

&&

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

&&

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