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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 201041
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
641 AM EDT MON MAY 20 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 SHOWERS AND
THUNDERSTORMS THROUGH TUESDAY. DRIER AND WARMER WEATHER EXPECTED
FOR MID WEEK BEFORE A COLD FRONT PUSHES ACROSS THE AREA
FRIDAY...BRINGING DRIER AND SLIGHTLY COOLER WEATHER FOR THE
WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
AS OF 630 AM MONDAY...SLOW-MOVING SHOWERS AND T-STORMS WITH HEAVY
RAINFALL MAY HAVE LED TO FLOODING ACROSS PORTIONS OF DARLINGTON AND
MARLBORO COUNTIES WHERE FLOOD ADVISORIES AND WARNINGS HAVE BEEN
ISSUED THIS MORNING. FLASH FLOOD GUIDANCE FROM THE ATLANTA RFC WAS
EXCEEDED BY RADAR-ESTIMATED RAINFALL TOTALS ACROSS SEVERAL DRAINAGE
BASINS NEAR THE PEE DEE RIVER...MAINLY ALONG A LINE FROM MONT CLARE
NORTH-NORTHEAST TOWARD BENNETTSVILLE. NO REPORTS OF FLOODING HAVE
YET BEEN RECEIVED...ALTHOUGH RADAR-ESTIMATED STORM-TOTAL RAINFALL
OVER 5.5 INCHES IS INDICATED NEAR THE PEE DEE RIVER EAST OF
SOCIETY HILL.

THE LATEST SEVERAL HRRR RUNS (06-08Z) FOCUS ADDITIONAL HEAVY
RAINFALL THROUGH THE MORNING HOURS ACROSS LUMBERTON...MARION...
CONWAY...WHITEVILLE AND ELIZABETHTOWN...WHERE UPWARD OF 3 INCHES OF
RAIN IS DEPICTED IN THE MODEL ACROSS A LARGE AREA. FORTUNATELY THESE
LOCATIONS RECEIVED FAIRLY LIGHT RAINFALL AMOUNTS YESTERDAY WHICH
MEANS A GOOD PORTION OF ANY NEW RAINFALL SHOULD BE ABSORBED BY SOIL
RATHER THAN CONVERTING IMMEDIATELY TO RUNOFF. HIGH POPS (60-80
PERCENT) WILL BE MAINTAINED IN THE FORECAST THROUGH AFTERNOON.

AT THE COAST SHOWERS HAVE SO BEEN GENERALLY LIGHTER WITH NO FLOODING
CONCERNS. ALTHOUGH THE LATEST FEW HRRR RUNS SHOW AT LEAST SOME
POTENTIAL FOR HEAVY RAIN DURING THE MORNING HOURS AT THE COAST...
THE DEVELOPMENT OF A SEABREEZE SHOULD HELP CLEAR THE BULK OF THESE
SHOWERS OUT WITHIN 5-10 MILES OF THE BEACHES THIS AFTERNOON.

A WEAK UPPER LEVEL DISTURBANCE WILL ELONGATE NORTH-TO-SOUTH TODAY
ACROSS THE CENTRAL CAROLINAS...EVENTUALLY CLEAVING INTO TWO
INDIVIDUAL PIECES TONIGHT. CYCLONIC FLOW SURROUNDING THIS FEATURE
ALOFT IS VERY WEAK AND STORM CELL MOTION IS ANTICIPATED TO BE SLOW
TODAY. WITH PRECIPITABLE WATER VALUES NOW IN THE SUMMER/TROPICAL
RANGE OF 1.6 TO 1.8 INCHES AND MODEL FORECAST SOUNDINGS SHOWING
ALMOST 10000 FEET OF WARM CONVECTIVE CLOUD DEPTH (LCL AROUND 2500 FT
VERSUS AN ENVIRONMENTAL FREEZING LEVEL OF 12500 FT) THERE IS A
GROWING POTENTIAL FOR HEAVY RAINFALL...PERHAPS EVEN EXCESSIVE
RAINFALL AND FLOODING LATER TODAY. I DO NOT PLAN TO ISSUE A FLOOD
WATCH...BUT WILL INCLUDE HEAVY RAIN MENTION IN THE FORECAST GRIDS
AND HAZARDOUS WX OUTLOOK.

A STABILIZING BOUNDARY LAYER AND A WEAKENING UPPER LEVEL DISTURBANCE
TONIGHT SHOULD PRODUCE A RAPID DECREASE IN COVERAGE OF SHOWERS.
SOUTH WINDS MAY STILL ADVECT NOCTURNAL MARINE CONVECTION ONSHORE SO
THE HIGHEST POPS (30-40 PERCENT) WILL REMAIN OVERNIGHT NEAR THE
BEACHES...WITH LESSER CHANCES INLAND. LOWS SHOULD FALL TO 66-69 FOR
MOST AREAS.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...HIGH PRESSURE OFFSHORE WILL CONTINUE ITS
INFLUENCE ACROSS THE CAROLINAS...BUT A DECREASING TREND IN
CONVECTION WITH WARMING TEMPS IS EXPECTED THROUGH THE SHORT TERM.
BUILDING 1000-500MB THICKNESSES AND SOME WEAK NVA BEHIND A DEPARTING
SHORTWAVE WILL CREATE SUBSIDENCE WITH INCREASED DRYING THROUGH THE
COLUMN. FORECAST PROFILES SUGGEST SIGNIFICANT DRY AIR ABOVE
800MB...AND THIS IS ECHOED IN PWATS FALLING TO 1.25 INCHES BY
WEDNESDAY. THIS WILL TEND TO INHIBIT MUCH IN THE WAY OF
CONVECTION...BUT WITH TEMPS RISING WELL INTO THE 80S...ISOLATED
CONVECTION WILL REMAIN POSSIBLE...ESPECIALLY TUESDAY. WILL CONTINUE
LOW-CHC POP TUESDAY AND SCHC WEDNESDAY...BUT WOULD NOT BE SURPRISED
IF WED ENDS UP BEING DRY ACROSS THE CWA.

TEMPS WILL RESPOND TO BULGING HEIGHTS...RISING FROM THE LOW/MID 80S
TUESDAY INTO THE MID/UPR 80S WEDNESDAY. LOWS WILL REMAIN WELL ABOVE
NORMAL FOR MID-MAY THANKS TO CONTINUED SOUTHERLY WINDS...FALLING
ONLY INTO THE UPPER 60S BOTH NIGHTS.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 300 AM MONDAY...PATTERN CHANGE TO OCCUR DURING THE EXTENDED AS
COLD FRONT CROSSES THE AREA FRIDAY...USHERING IN A MUCH DRIER
AIRMASS TO THE CAROLINAS.

BERMUDA HIGH AND MID LEVEL RIDGING WILL PERSIST AT THE START OF THE
PERIOD...BUT FULL LATITUDE TROUGH WILL BEGIN TO DISPLACE THE RIDGE
CAUSING INCREASED CONVECTIVE CHANCES AND SLIGHTLY COOLER TEMPS. GFS
HAS SPED UP TIMING OF FRONT CONSIDERABLY...WHICH DOESN`T MAKE A LOT
OF SENSE BASED OFF RESTRICTIVE ANTECEDENT FLOW OF THE UPPER
PATTERN...AND FAVOR THE SLOWER CMC/ECMWF WHICH HAS THE FROPA
OCCURRING FRIDAY AFTN. THIS WILL SUPPORT ANOTHER DAY OF CONVECTION
AHEAD OF THE FRONT...BUT DRYING WILL OCCUR RAPIDLY BEHIND IT AS HIGH
PRESSURE BUILDS IN FROM THE NW. WHILE OVERALL TEMPERATURE CHANGE
WILL BE MINIMAL...WITH TEMPS ONLY A FEW DEGREES COOLER DURING THE
WKND...IT WILL BE MUCH DRIER...AND A BEAUTIFUL WKND APPEARS TO BE IN
STORE FOR THE AREA WITH TEMPS SLIGHTLY BELOW CLIMO.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 06Z...NIGHTTIME SHOWERS ARE INCREASING IN COVERAGE OVER THE
EASTERN CAROLINAS AHEAD OF A WEAK UPPER LEVEL DISTURBANCE OVER THE
WESTERN CAROLINAS. MOISTURE FROM THESE SHOWERS SHOULD CREATE IFR
STRATUS IN FLO/LBT AFTER 08Z. ALONG THE COAST WARMER TEMPERATURES
DUE TO ONSHORE FLOW OFF THE ATLANTIC SHOULD MAINTAIN MVFR CIGS...
ALTHOUGH IT IS NOT IMPOSSIBLE THAT ISOLATED IFR CONDITIONS COULD
DEVELOP NEAR HEAVIER SHOWER ACTIVITY. AFTER DAYBREAK...CIGS WILL
GRADUALLY LIFT TO MVFR/VFR. SOUTHWEST WINDS WILL PREVAIL AOB 10 KTS
WITH GUSTS UP TO 18 KTS ALONG THE COAST LATER IN THE DAY. INCREASED
CHANCES FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
THROUGHOUT THE DAY...SLOWLY TAPERING OFF INTO THE EVENING HOURS.
FOR CURRENT FCST HAVE KEPT IN VCSH GIVEN UNCERTAINTY OF
TIMING/OCCURRENCE OF ANY CONVECTIVE ACTIVITY.

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

&&

.MARINE...
-- Changed Discussion --
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM MONDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
MARINE FORECAST THIS MORNING. PREVIOUS DISCUSSION FROM 300 AM
FOLLOWS...

THE OVERALL PATTERN WILL BE LITTLE CHANGED FROM YESTERDAY WITH
SURFACE HIGH PRESSURE REMAINING ANCHORED ALMOST 1000 MILES EAST OF
CAPE HATTERAS AND LOW PRESSURE MOVING SLOWLY ACROSS THE NORTHERN
PLAINS STATES. THIS WILL ENSURE A LIGHT TO MODERATE SOUTH WIND
ACROSS THE CAROLINA COASTAL WATERS TODAY AND TONIGHT.

SHOWERS AND EMBEDDED THUNDERSTORMS THIS MORNING SHOULD DECREASE IN
COVERAGE THIS AFTERNOON AS THE SEABREEZE CIRCULATION DEVELOPS...BUT
ANOTHER ROUND OF SCATTERED SHOWER ACTIVITY MAY DEVELOP TONIGHT. HIGH
MOISTURE CONTENT OF THE ATMOSPHERE MEANS HEAVY RAINFALL AND MARINE
VISIBILITY RESTRICTIONS ARE THE LARGEST THREATS.

SEAS CURRENTLY RANGE FROM 3-4 FT AT THE CAPE FEAR AREA BUOYS IN A
COMBINATION OF SOUTHEAST SWELL AND SOUTH WIND WAVES.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...RETURN FLOW AROUND BERMUDA HIGH PRESSURE
OFFSHORE CONTINUES THROUGH THE SHORT TERM...WITH SOUTHERLY WINDS OF
10-15 KTS COMMON EACH DAY. SEAS OF 2-3 FT TUESDAY WILL RISE TO 2-4
FT WEDNESDAY THANKS TO SLIGHTLY HIGHER WINDS. WHILE A DEAMPLIYFING
SE SWELL WILL BE PRESENT WITHIN THE WAVE SPECTRUM...SEAS WILL BE
PRIMARILY DERIVED FROM A SOUTHERLY 5-6 SEC WIND WAVE.

LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 300 AM MONDAY...SOUTHERLY WINDS AROUND 15 KTS TO START THE
PERIOD WILL VEER THROUGH THURSDAY TO THE W/SW AS A COLD FRONT
APPROACHES FROM THE NW. THIS FRONT WILL CROSS THE WATERS DURING
FRIDAY...TURNING WINDS QUICKLY TO THE WEST FRIDAY EVE WITH DECREASED
SPEEDS BEFORE WINDS INCREASE FROM THE NORTH FRIDAY NIGHT. SEAS WILL
RISE TO 3-5 FT THURSDAY NIGHT AHEAD OF THE COLD FRONT BEFORE FALLING
BACK TO 2-4 FT LATE FRIDAY THANKS TO THE OFFSHORE COMPONENT OF THE
WIND.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...TRA