-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 221809
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
209 PM EDT WED MAY 22 2013

.SYNOPSIS...
BERMUDA HIGH PRESSURE WILL DOMINATE THE WEATHER ACROSS THE EASTERN
CAROLINAS THROUGH THURSDAY. SHOWERS AND THUNDERSTORMS WILL INCREASE
THURSDAY AND THURSDAY NIGHT AHEAD OF AN APPROACHING COLD FRONT. THE
FRONT WILL CROSS THE REGION FRIDAY MORNING. A MUCH COOLER AND DRIER
AIRMASS WILL FOLLOW...COMPLEMENTS OF A CANADIAN HIGH PRESSURE...AND
AFFECT THE AREA THIS WEEKEND. THE HIGH WILL SLIDE OFF THE EAST COAST
EARLY NEXT WEEK WITH TEMPERATURES REBOUNDING TO NEAR NORMAL...ALONG
WITH AN INCREASE IN AFTERNOON SHOWERS AND THUNDERSTORMS.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
AS OF 1:45 PM WEDNESDAY...A BAND OF LIGHT TO MODERATE SHOWER
ACTIVITY WITH THE ISOLATED RUMBLE OF THUNDER IS MOVING RAPIDLY
INLAND ALONG THE SEA BREEZE FRONT THIS AFTERNOON. CONVECTIVE BAND
NOW APPROACHING THE I-95 CORRIDOR WITH WHICH IT IS ALIGNED WITH.
SOME LIGHT SHOWERS ARE MOVING IN OFF THE OCEAN SOUTH OF CAPE FEAR.
OTHERWISE...THE COASTAL COUNTIES WILL BE ON THE DRY SIDE FOR THE
REMAINDER OF THE AFTERNOON.

FOR TONIGHT GUIDANCE IS STILL IN GOOD AGREEMENT ON REDEVELOPMENT
OF CONVECTION...ESPECIALLY ALONG THE COAST IN THE VICINITY OF THE
CAPE FEAR REGION...AS AN UPPER IMPULSE LIFTS AN AREA OF SHOWERS
AND THUNDERSTORMS ASHORE FROM OVER THE WESTERN ATLANTIC. HAVE GONE
WITH SCATTERED CONVECTION TONIGHT FOR MUCH OF THE FORECAST AREA.
EXTENSIVE CLOUD COVER AND CONTINUED WARM...MOIST SOUTHERLY FLOW
WILL KEEP MINIMUM TEMPERATURES ABOVE NORMAL...IN THE MID 60S MOST
PLACES AND THE UPPER 60S AT THE COAST.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...THIS PERIOD WILL BE HIGHLIGHTED BY THE
EVOLUTION OF A RATHER DEEP MID-LEVEL TROF THAT WILL DOMINATE THE
WEATHER ACROSS THE FA BY THE END OF THIS PERIOD. AT THE BEGINNING OF
THE SHORT TERM...THE AMPLIFYING UPPER TROF IS PROGGED TO BE JUST
EAST OF THE MISSISSIPPI RIVER...AND BY LATE FRIDAY NIGHT ITS NORTH
TO SOUTH TROF AXIS WILL HAVE MOVED JUST OFF THE NORTH AND SOUTH
CAROLINA COASTS...VIA NAM AND GFS MODELS. MODELS AT TIMES HAVE TRIED
TO MAKE THIS AN AMPLIFIED FULL LATITUDE TROF BUT INDIVIDUAL
VORTS/IMPULSES ROTATING THROUGH THIS UPPER FEATURE...ARE PROGGED TO
MOVE AT DIFFERENT SPEEDS AND THUS PREVENTING THE CARVING OF A TRUE
FULL LATITUDE TROF. ONE OF THE STRONGER VORTS IS PROGGED TO TRACK
ACROSS THE FA FRIDAY AFTERNOON/EVENING AS DYNAMICS FROM THIS FEATURE
AND COLDER TEMPS ALOFT PROVIDE ENOUGH INSTABILITY FOR ISOLATED
CONVECTION.

AT THE SURFACE...WESTERN ATLANTIC RIDGING WILL CONTINUE ACROSS THE
FA EARLY THURSDAY. A PRE-FRONTAL OR LEE SIDE TROF ORIENTED N-S WILL
DEVELOP ACROSS THE WEST-CENTRAL CAROLINAS AND BECOME THE FOCUS FOR
CONVECTION DEVELOPMENT AS IT SLOWLY PROGRESSES EASTWARD. IN ADDITION
MID-DAY/AFTERNOON DIURNALLY INDUCED CONVECTION WILL BREAK OUT ACROSS
THE COASTAL PORTIONS OF THE ILM CWA. WILL INDICATE 50 POPS
INLAND...WITH 30-40 CLOSER TO THE COAST DURING THE DAY THURSDAY. FOR
THURSDAY NIGHT...THE APPROACHING COLD FRONT WILL BECOME THE PRIMARY
FORCE FOR INDUCING CONVECTION. HOWEVER...THE SUB-TROPICAL/TROPICAL
MOISTURE FEED WILL HAVE BEEN PUSHED OFFSHORE AND NO LONGER THE
PRIMARY SOURCE. THINKING IS THAT ENOUGH MOISTURE WILL REMAIN FOR
ADDITIONAL CONVECTION TO FIRE AHEAD OF THE COLD FRONT...DEPENDING
HOW MUCH THE ATM IS ABLE TO DE-STABILIZE FROM THE CONVECTION THAT
DEVELOPED EARLIER IN THE DAY. AS A RESULT...WILL HIGHLIGHT 40-50
POPS IN THE EVENING AND SLOWLY DROP THEM TO SLIGHT CHANCE OVERNIGHT.
MODELS AFTER MIDNIGHT FRIDAY...DIVERGE FROM ONE ANOTHER WITH RESPECT
TO THEIR SOLUTIONS RELATED TO THE TIMING AND PLACEMENT OF THE COLD
FRONT. FOR EXAMPLE THE NAM AND CANADIAN HAVE THE FRONT OFF THE
CAROLINA COASTS BY DAYBREAK FRI...WHEREAS THE GFS LAGS BEHIND AND
ONLY HAS IT PROGRESSING THROUGH THE COASTAL CAROLINAS BY DAYBREAK
FRI. WILL LEAN TOWARD THE SLIGHTLY SLOWER PROGRESSION OF THE CFP.
POST FRONTAL DRIER AIR FINALLY ADVECTS ACROSS THE FA DURING THE DAY
FRI. CANADIAN HIGH PRESSURE WILL FINALLY PROVIDE RELIEF FROM THE
HUMID SUBTROPICAL/TROPICAL AIR MASS THAT AFFECTED THE FA FOR MUCH OF
THIS WEEK.

AS FOR MAX/MIN TEMPS...A RANGE OF 80 TO 85 FOR HIGHS THU...SIMILAR
TO WHAT THE NAM/GFS MOS GUIDANCE SHOWS. THE COLD AIR ADVECTION
BEHIND THE CFP WILL LAG BEHIND...AND BE OFFSET BY A DOWNSLOPE
TRAJECTORY IN THE WIND FIELDS. AS A RESULT...HAVE GONE ABOVE
GUIDANCE FOR FRIDAYS HIGHS WITH THE COASTAL COUNTIES LIKELY TO BE
WARMER THAN INLAND. A COMPROMISED MOS GUIDANCE MIN FORECAST WAS
USED.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM WEDNESDAY...FOR SATURDAY THRU MONDAY MID LEVEL FEATURES
REMAIN RELATIVELY UNCHANGED WITH THE TROF AXIS ASSOCIATED WITH THE
UPPER TROF HAVING ONLY PROGRESSED JUST OFF THE EAST COAST. THE
CENTRAL U.S. WILL BE HIGHLIGHTED BY AN UPPER RIDGE WITH ITS AXIS
RUNNING N-S ALONG THE MISSISSIPPI RIVER. BY TUESDAY...THE EUROPEAN
FLATTENS THIS RIDGE WHEREAS THE GFS PROGRESSES IT EASTWARD AND
MAINTAINING ITS IDENTITY. PREFERRED THE GFS SOLUTION AT THIS POINT.
AT THE SFC...CANADIAN HIGH PRESSURE TO RIDGE ACROSS THE FA SATURDAY.
ITS CENTER IS PROGGED TO BREAK APART BY SUNDAY...WITH THE SOUTHERN
EXTENT OF ITS CENTER MOVING ACROSS AND OFFSHORE FROM THE CAROLINAS
MONDAY AND TUESDAY. SUBSIDENCE ALOFT WILL KEEP A LID ON THE
DIURNALLY DRIVEN CU FROM DEVELOPING IN THE VERTICAL. THEREFORE NO
POPS THROUGH SUNDAY. FOR LATE SUNDAY NIGHT THRU TUESDAY...MODELS ARE
HINTING AT A BACK-DOOR COLD FRONT DROPPING SOUTHWARD...AND BECOMING
STATIONARY JUST NORTH OF THE FA. THIS MAY BECOME AN AID TO POSSIBLE
MCS/MCC THAT DEVELOP WELL UPSTREAM MON AND TUE...WHICH WILL FOLLOW
THE NW-SE UPPER FLOW. TOO FAR OUT IN TIME TO PREDICT THEIR
TIMING...HOWEVER ENOUGH OF A POSSIBILITY TO PLACE A LOW CHANCE POP
IN THE GOING FORECAST.

FOR THIS UPCOMING MEMORIAL DAY WEEKEND...SATURDAY THROUGH MONDAY
MORNING TEMPS ACROSS THE FA WILL RUN 5 TO 10 DEGREES BELOW
NORMAL...ESPECIALLY WITH OVERNIGHT LOWS. FOR MONDAY THRU
TUESDAY...WILL BE LOOKING AT NEAR NORMAL TEMPS. IF THE BACK-DOOR
COLD FRONT DROPS FURTHER SOUTH THAN ANTICIPATED...THE NW FLOW AHEAD
OF IT COULD PUSH TEMPS WELL INTO THE 80S TO AROUND 90...MUCH HIGHER
THAN THE CURRENT MOS GUIDANCE.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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AS OF 18Z...MOST OF THE CONVECTION THIS AFTERNOON WILL BE BETWEEN
THE INLAND AND COASTAL TERMINALS...HOWEVER THINK FLO WILL SEE SOME
ACTION SOMETIME AFTER 18Z. VISIBILITIES COULD BE BRIEFLY IFR IN
THE SHOWERS. MOST OF THE ACTIVITY WILL BE DYING DOWN BY
EVENING...BUT ANOTHER SLUG OF MOISTURE WILL ADVECT IN FROM THE
SOUTH AT THE COASTAL TERMINALS BY MID TO LATE EVENING. EXPECT
SHOWERS TO CONTINUE OVERNIGHT WITH CEILINGS LOWERING TO NEAR IFR.
INLAND...EXPECT POSSIBLE IFR CONDITIONS AFTER MIDNIGHT WITH
ABUNDANT LOW LEVEL MOISTURE. THURSDAY...MORE SHOWERS ARE EXPECTED
WITH TROPICAL MOISTURE FLOWING NORTHWARD.

EXTENDED OUTLOOK...SHOWERS/T-STORMS POSSIBLE THURSDAY THROUGH EARLY
FRIDAY. OTHERWISE VFR.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
NEAR TERM /THROUGH TONIGHT/...
AS OF 1:45 PM WEDNESDAY...THE SEA BREEZE CIRCULATION HAS TURNED
WINDS NEAR-SHORE MORE EASTERLY. OTHERWISE...LATEST OBS SHOW LIGHT
SE WINDS WITH SEAS IN THE 3 TO 4 FT RANGE.

FOR THE REMAINDER OF THIS AFTERNOON AND OVERNIGHT WE WILL SEE
LITTLE CHANGE FROM PRESENT CONDITIONS. A STATIONARY BERMUDA HIGH
OVER THE WESTERN ATLANTIC WILL KEEP SOUTHERLY WINDS IN THE 10 TO
15 KT RANGE...WITH 2 TO 4 FT SEAS. WINDS WILL BE GUSTY THIS
AFTERNOON NEAR SHORE DUE TO THE SEA BREEZE CIRCULATION...WITH
GUSTS UP TO AROUND 20 KTS.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...WESTERN ATLANTIC RIDGING WILL PROVIDE A
RATHER SOLID 15 KT SOUTHERLY FLOW DURING THU...BECOMING SW LATE
THU AFTERNOON AND NIGHT. THE SFC PG WILL TIGHTEN BETWEEN THE
APPROACHING COLD FRONT AND THE WESTERN ATLANTIC HIGH CENTERED WELL
OFFSHORE FROM THE SE U.S.COAST. COULD SEE 15 TO 20 KT WITH SOME
HIGHER GUSTS. CFP SLATED FOR AFTER DAYBREAK FRI...WITH WINDS
VEERING TO W TO NW 10 TO 15 KT...INCREASING TO 15 TO 25 KT FRIDAY
NIGHT DUE TO COLD AIR ADVECTION COMBINED WITH A TIGHTENED SFC PG.
SIGNIFICANT SEAS WILL RANGE FROM 2 TO 4 FT THU...BUILDING TO 3 TO
5 FT LATE THU THROUGH EARLY FRI. TEMPORARILY DROPPING BACK TO 2 TO
4 FT DURING FRIDAY...THEN BUILDING BACK TO 3 TO 5 FT FRI NIGHT
WITH 6 FOOTERS POSSIBLE OUTER WATERS OFF CAPE FEAR. SIG. SEAS WILL
PRIMARILY BE DRIVEN BY AN ESE GROUND SWELL AT 8 TO 9 SECOND
PERIODS DURING EARLY THU...WITH 4 TO 6 SECOND PERIOD WIND DRIVEN
WAVES TO DOMINATE LATE THU THRU FRI NITE. SCEC CONDITIONS POSSIBLE
FOR ALL WATERS...WITH A BORDERLINE SCA FOR THE ILM NC WATERS
DURING THE INFLUX OF COLD AIR FRI NIGHT.

LONG TERM /SATURDAY THROUGH SUNDAY/...
AS OF 300 AM WEDNESDAY...POSSIBLE SCEC OR SCA CONDITIONS WILL
PEAK DURING EARLY SATURDAY...WITH A DIMINISHING AND SUBSIDING
TREND FOR WINDS AND SIGNIFICANT SEAS RESPECTIVELY DURING THE
LATTER 2/3RDS OF THIS PERIOD. ALL IN RESPONSE TO THE CENTER OF THE
MODERATING CANADIAN HIGH PUSHING ACROSS THE LOCAL WATERS SUNDAY
THROUGH SUNDAY NIGHT. WINDS ARE PROGGED TO BECOME VARIABLE IN
DIRECTION DURING SUNDAY AND SUNDAY NIGHT AT 10 KT OR LESS.
SIGNIFICANT SEAS WILL BE DRIVEN BY LOCALLY PRODUCED SHORT PERIOD
WIND DRIVEN WAVES ON SATURDAY...WITH AN 8 TO 9 SECOND PERIOD SMALL
EASTERLY SWELL DOMINATING ON SUNDAY.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...DCH
NEAR TERM...REK
SHORT TERM...DCH
LONG TERM...DCH
AVIATION...DL
MARINE...DCH/REK