FXUS61 KLWX 281942
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
242 PM EST SAT NOV 28 2009

.SYNOPSIS...
LOW PRESSURE WILL MOVE UP INTO THE CANADIAN MARITIMES TONIGHT...WHILE
HIGH PRESSURE BUILDS ACROSS THE MID ATLANTIC THIS WEEKEND. A COLD
FRONT WILL PASS THROUGH MONDAY...THEN HIGH PRESSURE BRIEFLY
RETURNS ON TUESDAY. LOW PRESSURE WILL LIKELY IMPACT THE AREA
DURING THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
STILL SOME LINGERING GUSTS FOR THE ERN HALF OF THE AREA...AS THE 
LAST WAVE OF UPPER ENERGY STREAMS OFF THE NEW ENGLAND COASTLINE INTO 
THE EVNG HRS. LOCALES E OF THE BLUE RIDGE STILL SHOWING G15-20MPH 
WINDS THO THESE NUMBERS WILL CONTINUE TO DROP OVER THE NEXT SEVERAL 
HRS /AND SO WILL TEMPS/. THE DRIER CONDITIONS /SFC DEWPOINTS IN THE 
U20S/ WILL ALLOW OVERNIGHT LOWS TO DROP INTO THE NEAR FREEZING 
REALM. MOST AREAS OUTSIDE THE IMMEDIATE DC/BALT METRO WILL LIKELY 
DROP TO WITHIN A 30-35 DEG RANGE...W/ LIGHT WINDS AS HIGH PRESSURE 
BUILDS IN FROM THE WEST.

&&

.SHORT TERM /SUNDAY/...
THE TRANSITION PERIOD BETWEEN SYSTEMS FOR THE MID ATLC WILL BE ABOUT 
A DAY...STARTING FROM LATER THIS EVNG AND LASTING THRU SUNDAY EVNG. 
WHAT APPEARS TO BE A QUIET WX-MAP ACROSS THE CONUS IS ACTUALLY A 
PRECURSOR TO ANOTHER COMPLEX SERIES OF WX-SYSTEMS THAT WILL AFFECT 
DIFFERENT PARTS OF THE NATION OVER THE COMING WEEK. THE FIRST OF 
THESE FEATURES WILL BE PART OF A MEANDERING UPPER CUT-OFF LOW OVER 
CNTRL CA CURRENTLY. AS THE LOW SLIDES DOWN INTO THE DESERT SW THRU 
THE NEXT DAY-OR-TWO...AN APPROACHING UPPER WAVE FROM THE NRN ROCKIES 
WILL QUICKLY SLIDE DOWN INTO THE NRN PLAINS/WRN GREAT LAKES OVER THE 
COURSE OF SUNDAY. 

BY LATE AFTN...THIS UPPER TROF /STRETCHING BACK DOWN INTO THE CNTRL 
PLAINS AND HAVING A WEAK CONNECTION TO THE DESERT SW UPPER 
LOW...WILL STREAM WEAKLY FORCED PRECIP FROM THE WEST COAST OF MEXICO 
ALL THE WAY TO SERN CANADA. NO WASH-OUT...JUST AREAS OF LIGHT RAIN 
ALONG A WEAK SFC BOUNDARY. BY LATE SUNDAY...THIS ACTIVITY WILL BE 
PUSHING INTO THE OHIO RVR VLY AND BEGIN TO AFFECT THE WRN ZONES W/ 
STEADY CLOUD COVER BY LATE SUN INTO THE OVERNIGHT HRS. 

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
EXPECT RETURN FLOW TO BE IN PLACE SUNDAY NIGHT WITH SURFACE HIGH 
PRESSURE OVER THE WESTERN ATLANTIC AND A COLD FRONT APPROACHING FROM 
THE WEST. COULD BE A FEW SHOWERS MAKING IT INTO THE HIGHLANDS LATE 
AT NIGHT...BUT A MORE LIKELY TIME FRAME IS MONDAY AS COLD FRONT 
MOVES ACROSS THE AREA. CONVERGENCE ALONG THE FRONT IS NOT FORECAST 
TO BE THAT GREAT...BUT THERE WILL BE SOME MID LEVEL SUPPORT IN TERMS 
OF PVA...SO THINK THAT A BAND OF SHOWERS WILL BE ABLE TO PROGRESS 
ACROSS THE CWA. 09Z SREFS FAVORS MORE CHANCE POPS AS OPPOSED TO 
HIGHER POPS. THIS IS LOWER THAN THE 12Z NAM MOS AND GFS MOS...AND 
CONTINUE TO PREFER LIKELY POPS ACROSS THE CWA. QPF IS EXPECTED TO BE 
LIGHT...ONE TO TWO TENTHS OF AN INCH. MODELS HAVE ALSO ACCELERATED 
THE FRONT AND THIS TREND IS PREFERRED. ADDED SOME TIMING DETAIL TO 
THE GRIDDED DATABASE.

CONTINUING THE SLIGHTLY FASTER TIMING...POPS DECREASE APPRECIABLY 
EARLY MONDAY EVENING EXCEPT ACROSS THE HIGHLANDS WHERE CHANCE POPS 
ARE MAINTAINED DUE TO DEVELOPING UPSLOPE SNOW SHOWERS.

UPSLOPE SNOW SHOWERS CUT OFF TUESDAY AS FLOW BECOMES LESS FAVORABLE 
WITH HIGH PRESSURE BUILDING INTO THE MID ATLANTIC. MEANWHILE...THE 
TAIL OF THE FRONT THAT PUSHES THROUGH THE CWA MONDAY WINDS UP ACROSS 
CENTRAL FLORIDA AND THE GULF OF MEXICO TUESDAY/TUESDAY NIGHT...AND 
GULF LOW PRESSURE DEVELOPS ALONG IT. WITH MID ATLANTIC HIGH PRESSURE 
MOVING OFF THE COAST BY 12Z WEDNESDAY...THIS WILL ALLOW A MOIST 
RETURN FLOW TO RE-DEVELOP WHICH WILL SEND MOISTURE FROM THE GULF LOW 
PRESSURE NORTHWARD ON WEDNESDAY. MODELS ARE A LITTLE SLOWER WITH 
RAIN ONSET...BUT CLOUDS WILL THICKEN UP AND RAIN MAY BREAK OUT LATER 
IN THE DAY ACROSS THE SOUTHERN HALF OF THE CWA WITH ISENTROPIC LIFT 
ON THE INCREASE. 

DISAGREEMENT WITH LOW PRESSURE TRACK CONTINUES. BUT WHETHER IT MOVES 
UP NEAR THE COAST OR UP THE APPALACHIANS THE RESULT IS THE 
SAME...RAIN WEDNESDAY NIGHT. TIMING DISAGREEMENT WILL ALSO NEED TO 
BE RESOLVED...AS IF THE LOW IS SLOWER TO EXIT THEN RAIN MAY LINGER 
INTO AT LEAST THURSDAY MORNING. HAVE CHANCE POPS NOW CONSIDERING THE 
EXIT UNCERTAINTY. 

IN THE WAKE OF LOW PRESSURE...UPSLOPE FLOW WILL BRING SNOW SHOWERS 
BACK TO THE HIGHLANDS THURSDAY NIGHT/FRIDAY. EAST OF THE MTNS SHOULD 
BE DRY THE BALANCE OF THE TIME...BUT AN UPPER TROUGH MAY KEEP SOME 
CLOUDS AROUND AND BELOW CLIMO TEMPERATURES ARE EXPECTED TO SETTLE 
IN. 

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
WINDS STILL THE ONLY CONCERN...THO THIS WILL ONLY BE FOR THE NEXT 
SEVERAL HRS...AND EVEN LESS FOR SITES W OF KIAD. WINDS HAVE SUBSIDED 
SUBSTANTIALLY FROM EVEN A FEW HRS AGO /MUCH LESS YESTERDAY/. EXPECT 
BREEZY CONDITIONS TO LINGER OVER THE REGION CLOSEST TO THE 
CHESAPEAKE BAY...AND SUBSIDE CLOSER TO SUNSET. AFTERWHICH...SOLID 
VFR CONDITIONS THRU THE TAF PERIOD. LIGHT SWLY WINDS TMRW...MAINLY 
CLR SKIES UNTIL THE LATE EVNG HRS.

COLD FRONT FRONT WILL MOVE ACROSS THE REGION ON MONDAY...PRODUCING 
SHOWERS THAT MAY CAUSE MVFR CONDITIONS. WIND SHIFT FROM SOUTHWEST TO 
NORTHWEST IS EXPECTED AROUND THE AFTERNOON PUSH ON MONDAY. HIGH 
PRESSURE BUILDS IN TUESDAY. LOW PRESSURE FROM THE GULF WILL MOVE 
NORTH TOWARD THE REGION WEDNESDAY/WEDNESDAY NIGHT.

&&

.MARINE...
SCA CANCELLED FOR THE WRN 2 ZONES OF THE TP...AS WINDS GENERALLY ARE 
SUBSIDING AREAWIDE. EVEN THE BAY IN MARGINAL SCA GUSTS...BUT THE 
NUMEROUS +20KT OBS WILL CONTINUE OVER THE BAY REGION THRU THE NEXT 
FEW HRS...W/ A GRADUAL WEAKENING TOWARD SUNSET FROM N-TO-S. AS THE 
UPPER LOW EXITS OFF NEW ENGLAND...SFC HIGH WILL BUILD IN BUT ONLY 
THRU THE NEXT 24 HRS...AHEAD OF ANOTHER LOW PRESSURE SYSTEM FOR 
EARLY NEXT WEEK. 

COLD FRONT MOVES ACROSS THE WATERS MONDAY AFTERNOON/EARLY 
EVENING...WITH A GUSTY NORTHWEST WIND DEVELOPING BEHIND THE FRONT 
MONDAY NIGHT/TUESDAY WHICH COULD EVENTUALLY WARRANT A SMALL CRAFT 
ADVISORY. HIGH PRESSURE TUESDAY NIGHT MOVES OFF THE COAST WEDNESDAY. 
GULF LOW PRESSURE MAY MOVE UP THE MID ATLANTIC WEDNESDAY 
NIGHT/THURSDAY...WHICH COULD ALSO INSTIGATE SMALL CRAFT ADVISORY 
CONDITIONS. 

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR 
     ANZ530>533-538>541.
     SMALL CRAFT ADVISORY UNTIL 1 AM EST SUNDAY FOR ANZ534-537-543.

&&

$$
SYNOPSIS...GMS/PELOQUIN
NEAR TERM...GMS
SHORT TERM...GMS
LONG TERM...PELOQUIN
AVIATION...GMS/PELOQUIN
MARINE...GMS/PELOQUIN