226 
FXUS61 KLWX 211450
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
950 AM EST SAT NOV 21 2009

.SYNOPSIS...
HIGH PRESSURE WILL CROSS THE REGION AND SETTLE OVER NEW ENGLAND 
THROUGH THE WEEKEND. A LOW PRESSURE AREA WILL MOVE UP COASTAL 
CAROLINA SUNDAY NIGHT INTO TUESDAY...BRINGING RAIN. HIGH PRESSURE
WILL RETURN LATE TUESDAY...THOUGH A COLD FRONTAL PASSAGE IS
EXPECTED IN THE MIDDLE TO LATE PORTIONS OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CURRENT ANALYSIS SHOWS A SURFACE HIGH THAT IS DRAPED ACROSS THE OHIO 
VALLEY INTO THE MID-ATLANTIC. THE JETSTREAM REMAINS SPLIT ACROSS THE 
CENTRAL AND EASTERN CONUS. AN UPPER-LEVEL LOW IN THE NORTHERN BRANCH 
IS LOCATED OVER THE OHIO VALLEY WHILE ANOTHER UPPER-LEVEL LOW IS 
LOCATED OVER TEXAS IN THE SOUTHERN BRANCH. 

A SOUTHWEST FLOW BETWEEN THESE TWO SYSTEMS HAS ALLOWED FOR HIGH 
CLOUDS TO OVERSPREAD THE AREA THIS MORNING. A STRATO CU DECK HAS 
ALSO SPREAD INTO THE AREA FROM THE NORTHWEST. HIGH CLOUDS SHOULD 
DISSIPATE FROM NORTHWEST TO SOUTHEAST DURING THE AFTERNOON HOURS AS 
THE DRY SLOT WRAPS AROUND THE UPPER-LEVEL LOW THAT IS LOCATED OVER 
THE OHIO VALLEY. THE STRATO CU DECK WILL HANG ON THROUGHOUT THE 
DAY...ESPECIALLY ACROSS THE NORTHERN AND WESTERN CWA. WILL CONTINUE 
MOSTLY CLOUDY/PARTLY SUNNY SKIES.  

SURFACE HIGH PRESSURE WILL KEEP DRY CONDITIONS IN PLACE. MAX TEMPS 
SHOULD BE NEAR CLIMO...IN THE 50S ACROSS MOST LOCATIONS...BUT 40S IN 
THE HIGHER ELEVATIONS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
CIRRUS AND LOWER STRATUS DECK IN THE NW ARE EXPECTED TO THIN OUT A 
BIT BY THE EVENING...HOWEVER MOISTURE FROM THE GULF STATES SYSTEM IS 
EXPECTED TO STREAM NORTHWARD OVERNIGHT. PARTLY CLOUDY/MOSTLY CLOUDY 
SKIES ARE EXPECTED MAINLY AFTER MIDNIGHT. MAV NUMBERS CONTINUE TO 
VERIFY SLIGHTLY BETTER THAN THE OTHER GUIDANCE...AND HAVE USED FOR 
THE OVERNIGHT MINS.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
SUNDAY...FLOW BECOMES NELY WITH HIGH PRESSURE OVER NEW ENGLAND AND 
AN APPROACHING COASTAL LOW OFF THE CAROLINAS. CLOUDS IN THE REGION 
DUE TO COASTAL SYSTEM...SO EXPECT MOSTLY SUNNY SKIES UNTIL CLOUD 
BANK ROLLS N-WARD IN ADVANCE OF THE LOW. WITH MORE SUN NRN 
ZONES...MAX TEMPS SUNDAY COULD BE THE INVERSE OF NORMAL WITH WARMEST 
/AROUND 60F/ LOCALES IN HARFORD/BALTIMORE AND COOLER /MID 50S/ 
NELSON/ALBEMARLE.

SUNDAY NIGHT THROUGH MONDAY NIGHT...HIGH PUSHES OFF NEW ENGLAND AND 
LOW PUSHES EAST OF HATTERAS...BRINGING ELY FLOW/CAD TO THE AREA. 
HAVING ALREADY MOISTENED...EXPECT LIGHT RAIN SPREADING EAST ACROSS 
THE AREA WITH EAST FACING SLOPES HAVING THE GREATEST PRECIP 
POTENTIAL DUE TO TOPOGRAPHY. SHOULD BE QUITE CLOUDY WITH SOME 
RAIN...EXPECT LOW DIURNAL RANGE...MINS MID 40S...MAXES MID 50S.

TUESDAY AND WEDNESDAY...A CLOSED LOW OVER THE CENTRAL PLAINS/MID 
WEST TO BREAK CAD WITH SWLY FLOW BY TUESDAY AFTERNOON /DID INCREASE 
POPS FOR TUESDAY MORNING ACROSS EASTERN HALF OF CWA DUE TO EXTENDED 
CAD/. WARMING TREND TUE /UPPER 50S/ TO WED /AROUND 60F/ AHEAD OF 
FROPA.

WEDNESDAY NIGHT/THANKSGIVING...S/W LOBE/S/ FROM THE LOW TO BRING ONE 
OR MORE COLD FRONTS PASSAGES IN MID TO LATE WEEK TIMEFRAME BRINGING 
PRECIP CHANCES ACROSS THE CWA. HOWEVER...MOISTURE AVAILABILITY FOR 
THE MID ATLANTIC IS UNCERTAIN. COLD AIR DOES LOOK TO FOLLOW THE 
FRONT...BRINGING A COOL DOWN AND MOUNTAIN WINTRY PRECIP.

THURSDAY NIGHT/FRIDAY...MODELS UNCERTAIN OF LOW INTENSITY AND 
TRACK...BUT THE POTENTIAL IS THERE FOR AN EARLY UPSLOPE SNOW EVENT 
IN NWLY FLOW AROUND THE BACKSIDE OF THE LOW FEEDING GREAT LAKE 
MOISTURE TO THE ALLEGHENY FRONT AND POSSIBLY RIDGES FURTHER EAST. 
WILL HAVE TO MONITOR FUTURE MODELS FOR CONSISTENCY/GREATER 
DISCERNMENT. IF ANYTHING...COOLING TREND LATE NEXT WEEK.

&&

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS THIS AFTERNOON. HIGH CLOUDS WILL DISSIPATE FROM 
NORTHWEST TO SOUTHEAST THIS AFTERNOON...BUT A BKN STRATO CU DECK 
WILL PERSIST THROUGH THE AFTERNOON. CIGS WILL REMAIN ABOVE 3KFT. THE 
STRATO CU DECK WILL DISSIPATE THIS EVENING. VFR CONDITIONS ALONG 
WITH LIGHT WINDS ARE EXPECTED MOST OF TONIGHT. MVFR VSBYS ARE 
POSSIBLE TOWARDS MORNING WITH PATCHY BR. 

ONSHORE NELY FLOW SETS UP SUNDAY...WITH MOISTENING/PRECIP BEGINNING 
BY LATE SUNDAY NIGHT AS ELY FLOW SETS UP ACROSS THE TERMINALS. LOW 
CIGS AND REDUCED VSBYS IN RAIN/DRIZZLE INTO TUESDAY MORNING. SWLY 
FLOW AHEAD OF THE NEXT COLD FRONT LATER TUESDAY/WEDNESDAY WITH 
IMPROVED AVIATION CONDITIONS. QUANTITY OF PRECIP ASSOCD WITH FRONT 
LOOKS TO BE LOW AT THIS TIME THOUGH WITH TIMING LATER 
WEDNESDAY/EARLY THURSDAY CERTAINLY PAY ATTENTION TO SUBSEQUENT 
FORECASTS.

&&

.MARINE...
NORTH-NORTHWEST WINDS ARE EXPECTED ACROSS THE MARINE AREA THROUGH 
TONIGHT. NO FLAGS ARE EXPECTED.  

HIGH PRESSURE BUILDING OVER NEW ENGLAND AND A COASTAL LOW MOVING UP 
THE CAROLINAS SUNDAY/NIGHT BRINGS ABOUT NELY FLOW. SMALL CRAFT 
ADVISORY WINDS POSSIBLE SUNDAY NIGHT THROUGH MONDAY NIGHT. SWLY FLOW 
AHEAD OF THE NEXT FRONT LATER TUESDAY AND WEDNESDAY. ONE OR MORE 
FROPAS LATER WEDNESDAY THROUGH FRIDAY TO BRING SOME PRECIP AND 
COLDER AIR.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

$$
LISTEMAA/LASORSA/BAJ