FXUS61 KLWX 110906
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
406 AM EST SAT FEB 11 2012

.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEAST OFF THE CAROLINAS TODAY AS A
STRONG COLD FRONT RAPIDLY APPROACHES FROM THE NORTHWEST...CROSSING
THROUGH THIS AFTERNOON. HIGH PRESSURE WILL BUILD ACROSS THE MID-
ATLANTIC STATES THROUGH EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
NRN STREAM TROUGH CURRENTLY POSITIVELY TILTED DOWN THE GREAT LAKES 
TO THE MID SOUTH WILL TRAIL A SRN STREAM TROUGH CURRENTLY ACROSS THE 
SERN CONUS THROUGH TODAY. THUS THE TWO SYSTEMS WILL PROVIDE TWO 
WAVES OF WINTRY WEATHER TO THE CENTRAL MID ATLANTIC. THE SRN STREAM 
WAVE HAS A SURFACE LOW ALONG CAPE HATTERAS THAT WILL RAPIDLY DEVELOP 
THROUGH TODAY AS IT MOVES NORTHEAST PAST THE MID ATLANTIC COAST. 

THE BAND OF SNOW AND RAIN /SNOW FROM BALTIMORE TO THE WRN DC SUBURBS 
AND WEST...RAIN EAST/ WILL CONTINUE TO SHIFT NORTHEAST OVER THE NEXT 
FEW HOURS. A QUICK HALF TO ONE INCH OF SNOW FELL ACROSS THE VA/MD 
PIEDMONT TO THE NORTHERN SHENANDOAH VALLEY WITH THIS BAND. EXPECT A 
FEW TENTHS OF AN INCH ALONG AND WEST OF THE I-95 CORRIDOR THROUGH 
SUNRISE BEFORE THIS BAND TAPERS OFF/SHIFTS EAST. THE BACK SIDE HAS 
MOVED ACROSS THE SHENANDOAH VALLEY AND THIS WILL CROSS THE PIEDMONT 
AND THEN THE BALT-WASH METRO OVER THE NEXT FEW HOURS.

LATER TODAY...THE COLD FRONT /STRETCHING FROM ABOUT CLEVELAND TO 
CHATTANOOGA AT 09Z/ WILL SHIFT EAST ACROSS THE MID ATLANTIC WITH 
SNOW SHOWERS/SQUALLS MOVING THROUGH THE CWA THROUGH THE AFTERNOON. 
WEST WINDS WILL BE PICKING UP THROUGH THE AFTERNOON...WITH A NOTABLE 
STRONG GUST FRONT/SQUALL MOVING THROUGH THE CWA WITH THE COLD AIR 
LATE THIS AFTERNOON. THEREFORE...DESPITE THE REPRIEVE IN 
SNOWFALL...THE WINTER WEATHER ADVISORY WILL REMAIN IN EFFECT THROUGH 
TODAY. AFTER THE COLD AIR/STRONG GUST FRONT COMES THROUGH A FEW 
LIGHT SNOW SHOWERS COULD OCCUR...THOUGH LESS SIGNIFICANT IN SNOW 
AMOUNTS...SO THE WINTER WEATHER ADVISORY MAY NOT HAVE TO BE 
EXTENDED. IT MAY NEED TO BE EXPANDED DEPENDING ON COVERAGE OF THESE 
SHOWERS/SQUALLS. WITH COLD AIR MOVING IN THROUGH THE DAY...EXPECT 
MOST PRECIP TO BE SNOW...EVEN IF TEMPS REACH THE LOW 40S. THE 
CONVECTIVE NATURE OF SHOWERS WILL EASILY DRAW DOWN COLD AIR DROPPING 
THE TEMPERATURE AND RESULTING IN SNOW.

TONIGHT...THE MOST SIGNIFICANT WEATHER TONIGHT WILL BE THE WIND. 
DRY/COLD AIR ADVECTION WILL BE STRONG...WITH 6-HR PRESSURE RISES OF 
AT LEAST 6 MB. WIND ADVISORIES ARE EXPECTED FROM THE BLUE RIDGE AND 
WEST...AND LIKELY EAST FROM THERE ACROSS THE BALT-WASH METRO. 
GFS/NAM BOTH INDICATE 50KT AT 925MB...BUT CONSULTATION WITH 
SURROUNDING OFFICES SUGGESTED TOO LOW OF CONFIDENCE ON PUTTING UP A 
HIGH WIND WATCH...HOWEVER HIGHER ELEVATIONS TONIGHT MAY REQUIRE A 
HIGH WIND WARNING. THE DAY SHIFT WILL HAVE TO DECIDE ON WIND 
HEADLINES. WITH THE COLD AIR AND STRONG WINDS...WIND CHILLS OF -5 TO 
-10 ARE EXPECTED ALONG/WEST OF THE ALLEGHENY FRONT. WIND CHILL 
ADVISORIES WILL BE NEEDED FOR SUCH WIND CHILLS.

&&

.SHORT TERM /SUNDAY/...
OFFSHORE LOW PRESSURE SUNDAY WILL MOVE FARTHER AWAY...WHILE HIGH 
PRESSURE OVER THE MISSISSIPPI VALLEY SLOWLY BUILDS EWD. PRESSURE 
GRADIENT EXPECTED TO REMAIN TIGHT THROUGHOUT THE DAY...SO GUSTY NW 
WINDS WILL CONTINUE. UPSLOPE SNOW OVER THE POTOMAC HIGHLANDS 
EXPECTED TO CONTINUE AT LEAST IN THE MORNING...BUT WIND DIRECTION 
MAY BECOME WESTERLY DURING THE DAY WHICH WOULD LIMIT THE MOISTURE 
FETCH FROM THE GREAT LAKES. WILL CONTINUE WINTER STORM WARNING FOR 
THIS REGION THROUGH SUNDAY SINCE THERE IS RELATIVELY LOW CONFIDENCE 
IN THE EXACT END TIME OF SNOW AT THIS POINT.

WITH STRONG COLD AIR ADVECTION STILL IN PLACE...HIGH TEMPS WILL BE 
AROUND 10 DEGREES BELOW NORMAL. UPPER 20S TO LOW 30S LIKELY OVER 
HIGHER ELEVATIONS....MID 30S ALONG THE I-95 CORRIDOR.  EARLY MORNING 
WIND CHILLS WILL BE IN THE SINGLE DIGITS ACROSS MOST OF THE 
REGION...AND LIKELY BELOW ZERO OVER HIGHER ELEVATIONS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGH PRESSURE RETURNS MONDAY AND MONDAY NIGHT...WITH DRY WEATHER AND 
DIMINISHING WINDS EXPECTED. DOWNSLOPE FLOW MONDAY WILL HELP TEMPS 
RETURN TO NEAR NORMAL. NEXT OPPORTUNITY FOR PRECIP WILL BE MONDAY 
NIGHT OVER WESTERN PORTIONS OF THE CWA...THEN TUESDAY AND TUESDAY 
NIGHT FOR THE REMAINDER...WITH THE POTENTIAL FOR A WEAK COLD FRONT 
PASSING THROUGH THE REGION.

AS THIS FEATURE ALSO DRIFTS OFF THE COAST...A SORT OF UNSETTLED 
SECOND HALF OF NEXT WEEK. ZONAL FLOW FROM THE PLAINS TO THE ATLC 
COAST...WHILE SEVERAL UPPER LOWS /IN DIFFERENT AREAS AT DIFFERENT 
TIMES/ BEGIN TO SPIN UP LARGER SYSTEMS TOWARD THE END OF NEXT WEEK. 
QUITE A MODIFICATION FROM THIS TIME YESTERDAY FOR THE FRI-SAT 
FRONTAL PASSAGE OVER THE AREA. INSTEAD...LONG RANGE GUIDANCE 
DEPICTING A STRONG BUT STRETCHED-OUT SYSTEM /WEST-TO-EAST/ OVER THE 
DEEP SOUTH AS OPPOSED TO THE MORE TYPICAL NORTH-SOUTH ORIENTATION.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
IFR WITH SNOW FROM MTN/BWI/DCA AND WEST IFR CIGS AND RAIN 
EAST...THROUGH THE REST OF TONIGHT AS A BAND OF PRECIP MOVES 
NORTHEAST. SNOW AT KMRB SHOULD END BEFORE 10Z. REPRIEVE FROM SNOW 
LATE MORNING THROUGH MIDDAY...WITH SNOW SHOWERS/SQUALLS THROUGH THE 
AFTERNOON AHEAD OF THE STRONG COLD FRONT THAT CROSSES FROM THE WEST 
LATE THIS AFTERNOON/EARLY EVENING. WINDS TONIGHT GUSTING 35 TO 40 KT 
ACROSS THE TERMINALS WITH SNOW SHOWERS TAPERING OFF IN THE EVENING.

VFR LIKELY SUNDAY. GUSTY NW WINDS CONTINUING...POSSIBLY ABOVE 30 KT 
MOST OF THE DAY.

VFR LIKELY MONDAY WITH LIGHT WINDS. OCCASIONAL SUB-VFR PSBL TUESDAY 
WITH A WEAK COLD FRONT APPROACHING. VFR EXPECTED AGAIN WEDNESDAY 
WITH HIGH PRESSURE OVER THE AREA. SUB-VFR POSSIBLE LATE THURSDAY 
INTO FRIDAY WITH ANOTHER COLD FRONT.

MARINE...GUSTY NW WINDS CONTINUE BEHIND THE DEPARTING LOW PRESSURE 
SYSTEM SUNDAY. GALE WARNING MAY NEED TO BE EXTENDED THROUGH AT LEAST 
PART OF THE DAY. CONDITIONS IMPROVE GRADUALLY SUNDAY NIGHT...BUT SCA 
GUSTS WILL BE POSSIBLE THROUGH SUNDAY NIGHT AND MUCH OF THE DAY 
MONDAY. THEN SUB-SCA CONDITIONS BY MONDAY NIGHT AND CONTINUING 
THROUGH THE REST OF THE WEEK.

&&

.MARINE...
NELY FLOW 10 TO 15 KT BECOMES NLY THROUGH THE MORNING WITH 
CHANNELING GUSTS TO AROUND 20 KT. FLOW BECOMES WLY THROUGH MIDDAY 
AND INCREASES WELL INTO THE SCA RANGE. A STRONG COLD FRONT CROSSES 
IN THE EARLY EVENING...WITH A QUICK INCREASE TO GALES THAT CONTINUES 
THROUGH TONIGHT.

GUSTY NW WINDS CONTINUE BEHIND THE DEPARTING LOW PRESSURE 
SYSTEM SUNDAY. GALE WARNING MAY NEED TO BE EXTENDED THROUGH AT LEAST 
PART OF THE DAY. CONDITIONS IMPROVE GRADUALLY SUNDAY NIGHT...BUT SCA 
GUSTS WILL BE POSSIBLE THROUGH SUNDAY NIGHT AND MUCH OF THE DAY 
MONDAY. THEN SUB-SCA CONDITIONS BY MONDAY NIGHT AND CONTINUING 
THROUGH THE REST OF THE WEEK.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER STORM WARNING UNTIL 7 PM EST SUNDAY FOR MDZ501.
     WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR 
     MDZ003>007-502.
VA...WINTER STORM WARNING UNTIL 7 PM EST SUNDAY FOR VAZ503.
     WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR VAZ028-
     504.
WV...WINTER STORM WARNING UNTIL 7 PM EST SUNDAY FOR WVZ501-503-505.
     WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR 
     WVZ050>053-055-502-504-506.
MARINE...SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 6 PM EST THIS 
     EVENING FOR ANZ530>543.
     GALE WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY FOR 
     ANZ530>543.

&&

$$
SYNOPSIS...KS
NEAR TERM...BAJ
SHORT TERM...KS
LONG TERM...KS
AVIATION...BAJ/KS
MARINE...BAJ/KS