000 
FXUS62 KILM 050726
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
326 AM EDT FRI OCT 5 2007

.SYNOPSIS...
HIGH PRESSURE ACROSS THE MID ATLANTIC REGION WILL SINK SLOWLY SOUTH
AND OVER THE CAROLINAS THROUGH EARLY NEXT WEEK. UNTIL THEN...BROAD
LOW PRESSURE IN THE BAHAMAS WILL MOVE WEST INTO THE GULF OF MEXICO
NEXT WEEK. THE HIGH WILL WEAKEN AS A COLD FRONT APPROACHES FROM
THE WEST BY WEDNESDAY...POSSIBLY STALLING NEARBY ON THURSDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE GFS AND TO SOME EXTENT THE WRF IS DEPICTING A RATHER WET 
SCENARIO FOR MOST OF THE AREA TODAY...AT LEAST EAST I-95. ONCE AGAIN 
FORCING IS SUBTLE...MOSTLY A FUNCTION OF 500MB VORTICITY. HOWEVER 
WITH PRECIPITABLE WATERS HOVERING AROUND TWO INCHES...IT WONT TAKE 
MUCH.

GFS/MAV NUMBERS SHOW LIKELY 12 HOUR POPS ALONG THE COAST AND 
NORTHWESTERN AREAS TRENDING LOWER AS YOU GO SOUTH AND WEST. STILL 
NOT OVERLY CONFIDENT WITH THE FORCING MECHANISMS BEING SO SUBTLE AND 
DIFFICULT TO RESOLVE. STILL...THINK THIS WILL BE THE BEST CHANCE OF 
RAIN IN SOME TIME AND WHILE NOT BUYING INTO LIKELY POPS...HAVE 
TRENDED STRONGLY IN THAT DIRECTION FOR THE LATER MORNING AND EARLY 
AFTERNOON HOURS. ALSO ADDED ISOLATED THUNDER FOR THE LATE MORNING 
AND AFTERNOON HOURS AS MODEL SOUNDINGS ARE SHOWING SUFFICIENT CAPE.

HIGH TEMPERATURE FORECAST WILL REMAIN CHALLENGING AND PRIMARILY A 
FUNCTION OF ANY BREAKS IN THE CLOUD COVER. THE LATEST GFS/MAV 
NUMBERS SEEM VERY REASONABLE WITH SLIGHTLY WARMER VALUES INLAND 
WHERE THERE MAY BE MORE INSOLATION. 

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
VERTICALLY DEEP HIGH PRESSURE CENTERED OVER THE MID ATLANTIC
STATES WILL MOVE LITTLE THROUGH THE WEEKEND. BROAD LOW PRESSURE IN
THE BAHAMAS WILL DRIFT WEST WITH TIME...ENDING UP IN THE EASTERN
GULF OF MEXICO BY SUNDAY NIGHT. THE PRESSURE GRADIENT BETWEEN
THESE TWO SYSTEMS WILL CONTINUE TO DIRECT AN EASTERLY LOW AND MID-
LEVEL FLOW ACROSS THE CAROLINAS THROUGH THE WEEKEND. 

THE UNSEASONABLY MOIST AIRMASS WE HAVE ENJOYED FOR THE PAST
SEVERAL DAYS WILL CONTINUE THROUGH SATURDAY. DESPITE MOSTLY CLOUDY
SKIES...ENOUGH HEATING SHOULD MAKE IT THROUGH TO DESTABILIZE THE
AIRMASS SATURDAY AFTERNOON AND LEAD TO 40-50% COVERAGE OF SHOWERS
AND STORMS. THERE WILL BE LITTLE IF ANY UPPER SUPPORT WITH THE
UPPER HIGH SITTING JUST TO OUR NORTH AND TROPOSPHERIC WINDS
GENERALLY LIGHT...THEREFORE CONVECTION SHOULD BE ALMOST A PURE-
INSTABILITY PLAY. A SURGE OF DRIER AIR WILL SPREAD IN FROM THE
EAST SATURDAY EVENING WITH CLEARING SKIES OVERNIGHT. SUNNY SKIES
ARE EXPECTED FOR SUNDAY.

LOWS TONIGHT WILL BE WITHIN A FEW DEGREES OF 70 WITH CLOUDS AND
ONSHORE WINDS. HIGHS SATURDAY SHOULD TOP OUT IN THE LOWER 80S MOST
AREAS. WITH THE DRIER AIR BUILDING IN SATURDAY NIGHT LOWS WILL
DROP DEEP INTO THE 60S. THAT SAME DRY AIR WILL ALLOW FOR MORE
SUNSHINE ON SUNDAY WITH HIGHS REACHING THE MID 80S.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
UPPER HIGH WILL PREVAIL ACROSS MOST OF THE EASTERN UNITED STATES 
SUNDAY THROUGH MONDAY BEFORE BECOMING SUPPRESSED TO THE SOUTHEASTERN 
STATES TUESDAY. BY MID-WEEK IT APPEARS THAT A STRONG UPPER LOW WILL 
MOVE ACROSS THE GREAT LAKES THEN MEANDER ACROSS THE OHIO VALLEY BY 
THU. THIS PATTERN LEADS TO A CHANGE FROM PREVIOUS THINKING WITH 
RESPECT TO THE SURFACE FEATURES. SPECIFICALLY...THE FRONT EXPECTED 
TO AFFECT THE AREA BY WED WILL STALL MUCH FARTHER NORTH AND ANOTHER 
FRONT WILL MOVE INTO THE AREA LATE IN THE WEEK. AS A RESULT... 
INCREASED MAX/MIN TEMPERATURES IN THE MID-WEEK TIME FRAME. STILL 
EXPECT TO SEE A FEW SHOWERS AROUND WITH WEAK COASTAL TROUGH WASHING 
OUT DURING SUNDAY. THE FIRST PART OF THE WEEK LOOKS VERY DRY UNDER 
RIDGING ALOFT. FINALLY BEGIN TO SEE SOME WEAK MOISTURE ADVECTION BY 
WED NIGHT AND THU AS THE MOVEMENT OF THE UPPER LOW PROMOTES DEEPER 
SOUTHWESTERLY FLOW AHEAD OF THE NEXT FRONT. WILL A SMALL POP IN THE 
GRIDS AT THAT TIME. TEMPS WELL ABOVE CLIMO FOR THE UPCOMING WEEK.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
BASICALLY THE SAME SITUATION AS LAST NIGHT...SOME SCATTERED ACTIVITY 
AFFECTING THE SOUTH CAROLINA TERMINALS...LIGHT RAIN SHOWERS THROUGH 
THE MORNING HOURS WHILE THE INLAND AND NORTH CAROLINA STATIONS WILL 
DEAL WITH THE POSSIBILITY OF FOG AND STRATUS DEVELOPMENT. HAVE 
ADDRESSED SHOWER ACTIVITY IN SOUTH CAROLINA WITH TEMPO/MVFR GROUPS 
THROUGH THE MORNING HOURS. USED TEMPO IFR GROUPS FOR JUST A COUPLE 
OF HOURS IN LBT. AND FLO. BASED ON CLOUD COVER AND A LITTLE STRONGER 
GRADIENT...ILM SHOULD REMAIN VFR. USED VCSH FOR THE LATE MORNING 
AFTERNOON HOURS IN ALL SITES AS THE GFS IS DEPICTING BETTER COVERAGE 
OF SHRA TODAY.

ISOLATED TO SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS 
THROUGH SUNDAY.

&&

.MARINE...
NEAR TERM /THROUGH 6 PM THIS EVENING/...
EAST TO NORTHEASTERLY FLOW OF 10-15 KNOTS WILL CONTINUE UNABATED 
TODAY AS SURFACE HIGH PRESSURE REMAINS ANCHORED OFF TO THE 
NORTHEAST. WAVEWATCH GUIDANCE AND REEFCAST ENSEMBLES ARE ONCE AGAIN 
IN GOOD AGREEMENT WITH SEAS OF 3-5 FEET.

SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... 
HIGH PRESSURE OFF THE MID ATLANTIC COAST WILL ONLY SLOWLY DRIFT
SOUTHWARD OVER THE WEEKEND. BROAD LOW PRESSURE IN THE BAHAMAS WILL
DRIFT SLOWLY WEST AND SHOULD END UP IN THE EASTERN GULF OF MEXICO
BY SUNDAY NIGHT. THE LONG EASTERLY FETCH BETWEEN THESE TWO SYSTEMS
WILL CONTINUE TO KEEP SEAS CHURNED UP LOCALLY THROUGH THE WEEKEND.
WAVEWATCH OUTPUT SHOWS 6-8 SECOND PERIODS WHICH IS RIGHT ON THE
BOUNDARY BETWEEN WIND WAVE AND SWELL...EVIDENCE OF THE RELATIVELY
LOCAL GENERATION ZONE FOR THE WAVES. WINDS ACROSS THE COASTAL
WATERS WILL AVERAGE EAST 10-15 KT WITH A FEW 20 KT GUSTS FROM TIME
TO TIME.

IT APPEARS SEAS WILL REACH 6 FEET IN THE COASTAL WATERS ADJACENT
TO CAPE FEAR BEGINNING TONIGHT...SO WILL BRING SMALL CRAFT
ADVISORIES BACK INTO EFFECT WITH THIS ISSUANCE. ACROSS THE SOUTH
CAROLINA WATERS SEAS MAY REACH 6 FT ON SATURDAY...STILL OUTSIDE
THE WINDOW OF ADVISORY ISSUANCE.

LONG TERM /MONDAY THROUGH TUESDAY/... 
THE CENTER OF SURFACE HIGH PRESSURE WILL SETTLE ACROSS THE
CAROLINAS BY MONDAY...FOCUSING THE STRONGER ONSHORE FETCH SOUTH OF
THE COASTAL WATERS. AS A RESULT...SEAS WILL GRADUALLY SUBSIDE
THROUGH THE LONG TERM PERIOD. WITH HIGH PRESSURE OVERHEAD TUESDAY
EXPECT TO SEE A PERIOD OF LIGHT AND VARIABLE WINDS WITH SEAS 3 FT
OR LESS.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM EDT 
     SUNDAY FOR AMZ250-252.

&&

$$

NEAR TERM...SHK
SHORT TERM...TRA 
LONG TERM...PFAFF 
AVIATION... SHK