-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 201722
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
122 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 /THROUGH TONIGHT/...
AS OF 1037 AM MONDAY...LATEST RADAR TRENDS SHOW THE AXIS OF HEAVIEST
RAINFALL INLAND IS SHIFTING EAST AND AWAY FROM AREAS THAT HAVE
RECEIVED PLENTIFUL TO EXCESSIVE RAINFALL. THIS EASTWARD PROGRESS WILL
HELP ALLEVIATE THE NEAR TERM FLOODING POTENTIAL...AND CURRENTLY NO
FLOOD WARNING OR ADVISORY PRODUCTS ARE IN EFFECT. THE FLOOD WARNING
FOR MARLBORO COUNTY LAST NIGHT AND THIS MORNING HAD VERIFICATION
WITH FLOODING OF MAIN ST IN BENNETTSVILLE WHERE EARLIER...WATER HAD
RISEN UPON THE ADJACENT SIDEWALKS. CURRENT ACTIVITY WILL WANE OVER
THE WATERS AS LOW-LEVEL BUOYANCY WEAKENS. THE AFTERNOON FOCUS WILL
BE IN FOLLOWING THE TRENDS OF THE MAIN AXIS OF RAINFALL INLAND
EDGING SLOWLY TOWARD THE COAST. OUR CENTRAL AND EVENTUALLY THE
EASTERN ZONES STAND TO RECEIVE AN INCH OR MORE OF RAIN AS THE SLOW
EAST COMPONENT OF THE STEERING FLOW PREVAILS. PORTIONS OF THE
PREVIOUS DISCUSSION FOLLOWS.

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.

&&

.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 /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
AS OF 18Z...MORE SHOWERS/T-STORMS ARE EXPECTED THIS AFTN WITH
MVFR/TEMPO IFR CONDITIONS IN HEAVIER DOWNPOURS. HAVE INCLUDED
VCSH/VCTS AT ALL TERMS WITH TEMPO GROUPS ATTEMPTING TO CAPTURE THE
TIMING OF PCPN BASED ON RADAR TRENDS AND HRRR OUTPUT. VFR/MVFR
LIKELY WILL PREVAIL WITH SHORT PERIODS OF IFR VSBYS IN +SHRA. MOST
PCPN SHOULD BE NEARING THE COASTAL TERMS BY MID-AFTN...THOUGH MORE
SCT SHOWERS INLAND ARE POSSIBLE AS WELL. RAIN CHANCES RAPIDLY
DIMINISH AFTER 00Z TUESDAY. FOG/STRATUS COULD BE AN ISSUE OVERNIGHT
WITH TODAYS PERSISTENT RAINFALL...HIGHEST CONFIDENCE AT KLBT/KFLO.
EXPECT MOSTLY CLOUDY SKIES AGAIN ON TUESDAY WITH S-SW WINDS 6-10
KTS. HAVE INCLUDED VCSH ALONG THE COAST TMRW TO ACCOUNT FOR SLIGHT
PCPN CHANCES AS THE UPPER DISTURBANCE NEARS THE COAST.

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

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1037 AM MONDAY...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.

&&

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

&&

$$


NEAR TERM...TRA/MJC
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...BJR/MJC