Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 220202
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1002 PM EDT THU AUG 21 2014

.SYNOPSIS...
HOT AND HUMID CONDITIONS WILL PERSIST THROUGH FRIDAY. A COLD
FRONT WILL SAG SOUTHWARD ACROSS THE AREA FRIDAY NIGHT AND
SATURDAY...BRINGING A HIGHER RISK FOR SHOWERS AND THUNDERSTORMS.
SURFACE HIGH PRESSURE WILL FOLLOW FROM THE NORTH EARLY NEXT WEEK
BRINGING MORE COMFORTABLE TEMPERATURE AND HUMIDITY LEVELS.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 PM THURSDAY...THUNDERSTORMS SURGED SOUTHEASTWARD INTO
NORTHERN NORTH CAROLINA MORE QUICKLY THAN EXPECTED...BUT A DRIER
AIRMASS THROUGHOUT THE 950-800 MB LAYER AND INCREASING DISTANCE FROM
THE UPPER DISTURBANCE MEANS THESE STORMS ARE DRYING UP. IT REMAINS
POSSIBLE AS THE UPPER DISTURBANCE REACHES SE NORTH CAROLINA LATE
TONIGHT THAT ISOLATED SHOWERS COULD REDEVELOP AS SHOWN ON THE 23Z
HRRR RUN. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS...

CONVECTION ALONG THE COAST HAS DIED AWAY LEAVING A MERGED
OUTFLOW/SEABREEZE BOUNDARY EASILY DISCERNIBLE ON RADAR IMAGERY FROM
NEAR ELIZABETHTOWN TO DILLON...MARION...AND INTO WESTERN GEORGETOWN
COUNTY. VISIBLE SATELLITE IMAGERY SHOWS NO CUMULUS CLOUDS ALONG THE
BOUNDARY SUGGESTING LIFT IS INSUFFICIENT TO PUSH PARCELS TO THEIR
LCL...LET ALONE THEIR LFC! DRY WEATHER IS ANTICIPATED THROUGH THE
EVENING HOURS WITH JUST SOME CIRRUS IN A NORTHWEST FLOW ALOFT.

IN THE UPPER LEVELS HIGH PRESSURE IS CENTERED OVER NEW ORLEANS WHILE
A SERIES OF SHORTWAVES HELPS AMPLIFY A TROUGH OFF THE NEW ENGLAND
COAST. ONE SUBTLE SHORTWAVE TROUGH MOVED OFF THE CAROLINA COAST A
FEW HOURS AGO...WHILE A SECOND DISTURBANCE UPSTREAM ACROSS
SOUTHWESTERN VIRGINIA IS HELPING INDUCE THUNDERSTORM ACTIVITY THERE.
MODELS CONFIRM SIMPLE LINEAR EXTRAPOLATION BRINGING THIS NEXT UPPER
DISTURBANCE SOUTHEASTWARD AND ACROSS SOUTHEASTERN NORTH CAROLINA
EARLY FRIDAY MORNING...5-8 AM EDT. LAPSE RATES ALOFT WILL CERTAINLY
BE STEEP ENOUGH TO SUPPORT CONVECTION...HOWEVER RATHER DRY AIR
LURKING WITHIN THE 950-800 MB LAYER SHOULD MAKE IT TOUGH FOR MUCH
CONVECTION TO SURVIVE THIS FAR SOUTHEASTWARD.

LOWS TONIGHT SHOULD REACH 73-76 FOR MOST AREAS...WITH 500-1000 FOOT
WIND SPEEDS ARGUING FOR ONLY A SMALL POTENTIAL FOR FOG.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 PM THURSDAY...THE STRONG MID AND UPPER LEVEL RIDGE WILL
BEGIN TO RETROGRADE...ALLOWING A TROUGH OFF THE EAST COAST TO DIG
SOUTHWARD. THIS WILL ALLOW A COLD FRONT TO OUR NORTH TO SAG
SOUTHWARD AND WE EXPECT THIS FRONT TO SLOWLY BACKDOOR THROUGH THE
FORECAST AREA FRI NIGHT AND SAT. SHORTWAVES TOPPING THE AMPLIFIED
RIDGE MAY SERVE TO ENHANCE THE COVERAGE AND INTENSITY OF
CONVECTION AND ALTHOUGH TIMING IS DIFFICULT AT THIS JUNCTURE...
WILL SHOW POPS TRENDING TO A HIGHER PROBABILITY SAT AND SAT NIGHT.
THE CONVECTION WHILE STILL GENERALLY SLOW MOVING...SHOULD PICK UP
THE PACE THIS PERIOD AS COLUMNAR WINDS INCREASE SLIGHTLY.

FRI SHOULD BE THE WARMEST DAY OF THE TWO AND THUS THE MOST
UNCOMFORTABLE. HOWEVER...THERE APPEARS TO AGAIN BE ENOUGH DRIER
AIR IN THE MID LEVELS SO THAT WHEN MIXING BECOMES DEEPER MIDDAY
AND THROUGH THE AFTERNOON...DEWPOINTS WILL AGAIN DROP...WITH MANY
AREAS AWAY FROM THE IMMEDIATE COAST DROPPING TO THE UPPER 60S AND
LOWER 70S. THUS...EVEN WITH THE INTENSE HEATING...TEMPS IN THE
MID AND UPPER 90S FRI...IT WILL BE A STRUGGLE TO MEET HEAT
ADVISORY CRITERIA IN MOST LOCATIONS. THE BEST CHANCE FOR MARGINALLY
MEETING CRITERIA WILL BE ACROSS THE SOUTHERN PEE DEE AND PERHAPS
PORTIONS OF THE GRAND STRAND. AT THIS TIME...WILL HIGHLIGHT THE
HEAT AND HUMIDITY IN THE HWO...BUT REFRAIN FROM ISSUING AN
ADVISORY. MORE WIDESPREAD CLOUDINESS DEVELOPING SAT SHOULD HELP TO
KEEP TEMPS DOWN A CATEGORY OR SO...WILL GO FOR WIDESPREAD LOWER TO
MID 90S. THE SEABREEZE WILL MOVE INLAND BOTH DAYS...MORE SO ON
SAT... KEEPING DAYTIME HIGHS LOWEST ALONG THE IMMEDIATE COAST.
NIGHTTIME VALUES ACROSS THE FORECAST AREA WILL BE A LITTLE ABOVE
CLIMATOLOGY FOR LATE AUG.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 300 PM THURSDAY...MID TO UPPER LEVEL PATTERN AMPLIFIES AS THE
RIDGE BUILDS UP FROM THE MISSISSIPPI VALLEY INTO NEW ENGLAND THROUGH
EARLY NEXT WEEK AND THEN EXPANDS EASTWARD OVER THE SOUTHEAST COAST
THROUGH THE WEEK. THIS WILL HELP TO PUSH COLD FRONT FARTHER SOUTH
THROUGH SUNDAY AS SURFACE HIGH BUILDS DOWN FROM THE NORTHEAST
THROUGH THE WEEK. EXPECT LINGERING CLOUDS AND SHOWERS ON SUNDAY TO
SHIFT SOUTH THROUGH THE DAY AS COLD FRONT MOVES SOUTH. THEN THE
BUILDING RIDGE SHOULD HELP TO SUPPRESS ANY WIDESPREAD OR STRONG
CONVECTION THROUGH MUCH OF THE WEEK PRODUCING A QUIETER WEATHER
PERIOD. TEMPS WILL BE BACK DOWN TO NORMAL BEHIND COLD FRONT WITH
HIGHS BETWEEN 85 AND 90 MOST DAYS AND OVERNIGHT LOWS BETWEEN 65 AND
70.

AS FOR THE TROPICAL SYSTEM APPROACHING THE WINDWARD ISLANDS
MENTIONED PREVIOUSLY...THE MODELS REMAIN FAIRLY INCONSISTENT AS TO
THE EXACT TRACK OR INTENSITY. THE GFS WAS TRACKING IT UP INTO THE
GULF COAST A FEW DAYS AGO AND THEN HAS PROGRESSIVELY SHIFTED EAST
NOW SHOWING MORE OF A TRACK UP THROUGH THE ATLANTIC WATERS EAST OF
COASTAL CAROLINAS LATER NEXT WEEK. THE ECMWF HAS BEEN THE FARTHEST
EAST AND FASTEST MODEL WITH THE SYSTEM. AT THIS POINT DECENT SWELLS
MAY REACH OUR COASTAL WATERS BY MID WEEK BUT AS FAR AS WEATHER...TOO
MUCH UNCERTAINTY STILL EXISTS.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 00Z...VFR CONDITIONS THIS EVENING AS EARLIER CONVECTION HAS
LONG SINCE DISSIPATED. REGIONAL RADAR IMAGERY SHOWS A LINE OF STORMS
OVER VIRGINIA DIVING DOWN WITHIN THE NORTHWEST FLOW ALOFT. THOUGH
VCSH CANNOT BE RULED OUT AT KLBT/KILM EARLY FRI MORNING...THE MORE
NOTABLE IMPACT WILL BE AN INCREASE IN DEBRIS CLOUD COVER OVERNIGHT.
THIS SHOULD HELP MITIGATE THE FOG THREAT...DESPITE THE LIGHT/CALM
WINDS EXPECTED AFTER 06Z FRI. STILL EXPECT SOME MVFR VSBYS TOWARD
DAYBREAK...ESPECIALLY ALONG THE COAST WHERE EARLIER RAINFALL HELPED
TO COOL AND MOISTEN THE LOW LEVELS. VFR WILL PREVAIL DURING THE DAY
FRI WITH WEST WINDS AOB 8 KTS EARLY...BECOMING S-SW AROUND 10 KTS AT
THE COASTAL TERMS FOLLOWING SEA BREEZE PASSAGE. HIGH PRESSURE ALOFT
WILL CONTINUE TO EXERT ITS INFLUENCE ON THE AREA...WITH ONLY SLIGHT
CHANCES OF ISOLATED CONVECTION IN THE AFTN.

EXTENDED OUTLOOK...CHC AFTERNOON/EVENING SHRA/TSRA THROUGH SUNDAY.
EXPECT VFR MON/TUE WITH HIGH PRESSURE OVER THE EAST COAST.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 PM THURSDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
FORECAST. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS...

THE PRESSURE PATTERN OVER THE CAROLINAS IS QUITE WEAK THIS EVENING.
LOW PRESSURE IS LOCATED ACROSS THE PLAINS STATES AND HIGH PRESSURE
IS WELL OFFSHORE. AN OLD STATIONARY FRONT HAS DECAYED TO A SIMPLE
LOW PRESSURE TROUGH INLAND. THIS BOUNDARY HAS MERGED WITH TODAY`S
SEABREEZE AND EARLIER THUNDERSTORM OUTFLOWS AND IS NOW LOCATED JUST
EAST OF INTERSTATE 95. SOUTHWEST WINDS AROUND 10 KNOTS SHOULD VEER A
LITTLE MORE WESTERLY OVERNIGHT...WITH SEAS AROUND 2 FEET. THE
POTENTIAL FOR FURTHER THUNDERSTORM ACTIVITY IS RATHER LOW...HOWEVER
AN UPPER LEVEL DISTURBANCE CURRENTLY PRODUCING THUNDERSTORMS ACROSS
SOUTHWESTERN VIRGINIA WILL SWEEP SOUTHEASTWARD AND MAY AFFECT THE
CAPE FEAR AREA BEGINNING AROUND 5 AM.

SHORT TERM /FRIDAY THOUGH SATURDAY NIGHT/...
AS OF 300 PM THURSDAY...SW WINDS WILL PERSIST INTO FRI NIGHT. A
COLD FRONT WILL SLOWLY SAG SOUTH ACROSS THE WATERS LATE FRI NIGHT
AND SAT AND THIS WILL SERVE TO SHIFT WINDS TO A MORE NORTHERLY
DIRECTION AND THEN MORE EASTERLY SAT AFTERNOON AS THE SEABREEZE
DEVELOPS. WINDS SAT NIGHT WILL BACK TO NE AND INCREASE AS A MODEST
SURGE DEVELOPS SOUTHWARD ACROSS THE WATERS. HIGHEST WIND SPEEDS
WILL BE FRI AFTERNOON AND NIGHT AND THEN AGAIN OVERNIGHT SAT...UP
TO AROUND 15 KT. SEAS WILL BE 2 TO 3 FT WITH SOME 4 FT SEAS
DEVELOPING FRI NIGHT ACROSS THE OUTERMOST WATERS. THESE 4 FT SEAS
WILL BECOME MORE WIDESPREAD FROM NORTH TO SOUTH LATE SAT NIGHT.

LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 300 PM THURSDAY...HIGH PRESSURE WILL BUILD DOWN BEHIND COLD
FRONT FROM THE NORTHEAST THROUGH EARLY NEXT WEEK. THIS WILL PRODUCE
A NORTHEAST SURGE IN WINDS WITH PERSISTENT NE FLOW UP TO 15 KTS
CONTINUING THROUGH MONDAY. MAY SEE AN INCREASE IN WINDS AND SEAS BY
TUESDAY AS A TROPICAL SYSTEM BEGINS TO MAKE PROGRESS NORTH HELPING
TO TIGHTEN THE GRADIENT AND INCREASE WINDS AND SWELLS. FOR NOW WILL
SHOW INCREASE IN SEAS UP TO 4 TO 5 FT LATE SUNDAY INTO MONDAY AND
THEN FURTHER INCREASE POSSIBLY UP TO ADVISORY LEVELS BY MID WEEK.

&&

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

&&

$$

NEAR TERM...TRA
SHORT TERM...RJD
LONG TERM...RGZ
AVIATION...BJR





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