000
FXUS61 KLWX 100731
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
331 AM EDT FRI SEP 10 2010

.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL CONTINUE ACROSS THE MID ATLANTIC
THROUGH TONIGHT...MOVING OFFSHORE EARLY SATURDAY. A COLD FRONT
WILL CROSS THE AREA LATE SATURDAY NIGHT OR EARLY SUNDAY...
ACCOMPANIED BY SCATTERED TO NUMEROUS SHOWERS. HIGH PRESSURE WILL
BRIEFLY BUILD OVERHEAD ON MONDAY...BUT ANOTHER COLD FRONT IS
EXPECTED BY MID WEEK.

.NEAR TERM /TODAY/...
TEMPS A BIT COOLER...WINDS A BIT LIGHTER - BUT ALL-IN-ALL FRI WILL
BE PRETTY SIMILAR TO THU. THE UPPER LOW RESPONSIBLE FOR THE AREA/S
WX OVER THE PAST FEW DAYS WILL ONLY HAVE MOVED A COUPLE HUNDRED
MILES ESE OF ITS POSITION 24 HRS BEFORE. THIS WILL KEEP GENERALLY
THE SAME ATMOSPHERIC REGIME STATIONED ACROSS GENERALLY THE SAME
AREAS. MEANWHILE...ACROSS THE NRN PLAINS/NRN ROCKIES - ANOTHER
STRONG LOW PRESSURE SYSTEM IS GEARING UP TO MAKE AN QUICK MOVEMENT
ACROSS THE GREAT LAKES AND OHIO VLY OVER THE NEXT COUPLE OF DAYS.

THE REMNANTS OF FORMER TROPICAL SYSTEM HERMINE WILL CONTINUE TO
DISSIPATE AS THE FEATURE DRIFTS TOWARD THE CONFLUENCE OF THE MS/OH
RIVERS. THE NRN PLAINS STORM SYSTEM WILL BE AT ITS STRONGEST OVER
THE NEXT 24 HRS...THEN THE NRN STREAM VORT WILL WRAP AROUND THE
UPPER LOW AS IT PULLS INTO SRN CANADA. NORMALLY SUCH A SYSTEM WOULD
BASICALLY DISSIPATE AND THE COLD FRONT WOULD WEAKEN UPON ITS
APPROACH TO THE APLCN CHAIN. WITH THIS SCENARIO HOWEVER...A STRONG
PUSH FROM ANOTHER AREA OF UPPER VORTICITY WILL TILT THE UPPER TROF
NEGATIVE AND KEEP THE FRONTAL REGION MOVING STEADILY ACROSS THE MID
MS VLY AND INTO THE OHIO VLY...AND W/ SPEED...LATER TODAY INTO SAT.

WELL BEFORE THIS SYSTEM AFFECTS THE MID ATLC REGION...ANOTHER
BEAUTIFUL LATE SUMMER/TRANSITION DAY AHEAD FOR THE REGION. TEMPS
WILL AGAIN STRUGGLE TO REACH 80 /EXCEPT IN THE SRN HALF OF THE CWA/.
WINDS WILL AGAIN GUST IN THE 20-25MPH RANGE DURING THE DAYTIME
HRS.../SLIGHTLY LOWER THAN YESTERDAY AFTN-EVE/. SKIES WILL AGAIN BE
MOSTLY CLEAR ACROSS THE SWRN HALF OF THE CWA AND PARTLY CLOUDY FOR
THE NERN HALF - AGAIN MUCH LIKE YESTERDAY.

.SHORT TERM /TONIGHT/...
ANOTHER COPY/PASTE OVERNIGHT PERIOD FROM THE CURRENT OVERNIGHT
PERIOD. WINDS WILL BE A BIT LIGHTER TONIGHT AND DEWPOINTS WILL BE A
COUPLE OF DEGREES HIGHER...WHICH WILL MODERATE TEMPS A DEGREE OR TWO
HIGHER THAN THE CURRENT CONDITIONS. SKIES WILL CLEAR OUT JUST AHEAD
OF THE UPPER MIDWESTERN LOW PRESSURE SYSTEM.

.LONG TERM /SATURDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL MOVE OFFSHORE EARLY SATURDAY. A WARM FRONT WILL
BEGIN TO MOVE NORTHWARD FROM THE SOUTHERN STATES...WHILE A COLD
FRONT APPROACHES FROM THE OHIO VALLEY. THERE ARE SOME DIFFERENCES
BETWEEN THE MODELS ON EXACTLY HOW FAR THE WARM FRONT MAKES IT NORTH
BY LATE SATURDAY/EARLY SUNDAY. THE GFS IS MORE AGGRESSIVE...WHILE
THE NAM IS SLOWER TO MOVE THE BOUNDARY NORTHWARD. THIS IS VERY WELL
DEPICTED IN THE MAX TEMP GUIDANCE FOR SUNDAY...WITH THE MET BEING
MUCH COOLER THAN THE MAV. HAVE CHOSEN TO TAKE A BLEND...AND ENDED UP
SOMEWHERE IN THE MIDDLE OF MET/MAV/NAM12/MOSGUIDE/SREF.

ALSO IN THE SATURDAY/SUNDAY TIME FRAME...HAVE UPPED THE POPS FROM
CHANCE TO LIKELY LATE SATURDAY NIGHT. SREF GUIDANCE CONTINUES TO
INDICATE AT LEAST LIKELY POPS ACROSS THE CWFA...SO HAVE CHOSEN TO
BUMP UP TO BETWEEN 60 AND 70 PERCENT IN MOST LOCALES. AVERAGE QPF
EXPECTED IS AROUND ONE QUARTER OF AN INCH...MUCH NEEDED.

OTHERWISE...NO MAJOR CHANGES TO THE REMAINDER OF THE FORECAST FOR
THE LONG TERM. TEMPS LOOK TO STAY AT OR SLIGHTLY BELOW NORMAL FOR
MINS AND MAXS WITH A LONGWAVE MID LEVEL TROUGH OVERHEAD. COLD FRONT
ON TUESDAY/WEDNESDAY STILL LOOKS TO BE MOSTLY DRY.

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
SOLID VFR CONDITIONS OVERNIGHT - W/ LIGHT NWLY WINDS - NEAR CALM AND
MOSTLY CLEAR SKIES. FRI WILL BE MUCH LIKE THU W/ WINDS INCREASING
BACK INTO THE 15-20KT RANGE BY MID MORNING...LINGERING INTO THE LATE
AFTN-EVE AND AGAIN SUBSIDING. THE DAYTIME 5-7KFT CLOUD DECKS WILL
DISSIPATE ACROSS NERN MD/POTOMAC RVR VLY.

SUB VFR CIGS/VSBYS STILL ANTICIPATED OVERNIGHT SATURDAY AND SUNDAY
AS A COLD FRONT CROSSES THE REGION. CONDITIONS EXPECTED TO IMPROVE
LATER SUNDAY AFTERNOON AS HIGH PRESSURE BUILDS OVERHEAD AND REMAINS
THROUGH MONDAY. ANOTHER COLD FRONT IS EXPECTED TUESDAY INTO
WEDNESDAY...BUT ONLY A WIND SHIFT IS EXPECTED WITH THIS SYSTEM.

.MARINE...
SCA CONDITIONS HAVE STATIONED ACROSS THE UPPER-MIDDLE BAY
OVERNIGHT...W/ THE REST OF THE WATERS SOLIDLY NEAR 10KT. THIS WILL
LIKELY CONTINUE INTO THE PRE-DAWN HRS. DAYTIME MIXING WILL AGAIN
CREATE NEAR 20KT GUSTS ACROSS MUCH OF THE BAY/TP WHICH WILL THEN
SUBSIDE TOWARD EARLY EVE FRI.

SOME CHANNELING UP THE BAY IS ANTICIPATED LATE SATURDAY NIGHT INTO
SUNDAY AHEAD OF A COLD FRONT. WIND SPEEDS TO INDICATE THE
POSSIBILITY OF A LOW END SCA. COLD FRONT MOVES THROUGH THE WATERS ON
SUNDAY...BRINGING NUMEROUS SHOWERS. HIGH PRESSURE BUILDS OVERHEAD
LATER SUNDAY INTO MONDAY. A SECOND FRONT IS EXPECTED ON
TUESDAY...WITH ANOTHER WIND SHIFT.

.FIRE WEATHER...
EVEN W/ LIGHTER NWLY WINDS AND SLIGHTLY COOLER CONDITIONS TODAY -
THE AREA REMAINS VERY DRY...W/ MUCH OF THE AREA STILL IN THE
LOWER-MID DROUGHT CATEGORIES. MORE ELEVATED FIRE WX CONCERNS FOR
TODAY BUT SLIGHTLY LESSER FROM THU AND ESPECIALLY WED. ANOTHER SPS
MAY BE WARRANTED FOR THE WINDY/DRY CONDITIONS TODAY.

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR
     ANZ530533-538541.
     SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 6 PM EDT THIS
     EVENING FOR ANZ534537-542-543.

SYNOPSIS...LISTEMAA
NEAR TERM...GMS
SHORT TERM...GMS
LONG TERM...LISTEMAA
AVIATION...GMS/LISTEMAA
MARINE...GMS/LISTEMAA
FIRE WEATHER...GMS