FXUS61 KLWX 220202
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
902 PM EST MON DEC 21 2009

.SYNOPSIS...
HIGH PRESSURE ACROSS THE AREA THROUGH WEDNESDAY NIGHT. LOW PRESSURE
WILL TRACK NORTH FROM THE SOUTHERN PLAINS THROUGH THE GREAT LAKES
THURSDAY THROUGH SATURDAY. AN ASSOCIATED COLD FRONT CROSSES THE
MID ATLANTIC CHRISTMAS DAY INTO SATURDAY. THIS SYSTEM WILL LIKELY
BRING WINTRY PRECIPITATION FOLLOWED BY RAIN.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
HIGH PRESSURE CONTINUES TO BUILD ACROSS THE MID ATLANTIC OVERNIGHT. 
STRATO CU DECK HAS FINALLY BEGUN TO DIMINISH IN COVERAGE EAST OF THE 
BLUE RIDGE MOUNTAINS. ASSOCIATED MID LEVEL SHEAR AXIS WILL CONTINUE 
PULLING OFF TO THE NORTH...WITH CONTINUED DECREASING CLOUDINESS 
OVERNIGHT FROM THE SHENANDOAH VALLEY EASTWARD. CLOUDS ACROSS THE 
WESTERN AREAS...ESPECIALLY THE WESTERN FACING RIDGES...WILL HANG 
TOUGH OVERNIGHT AND SKIES ARE NOT EXPECTED TO CLEAR. SCATTERED LIGHT 
SNOW SHOWERS WILL ALSO CONTINUED ACROSS THE WESTERN RIDGES 
OVERNIGHT.  

HAVE POPULATED GRIDS WITH THE NEWEST WIND GRIDS/GUSTS AND TWEAKED ON 
THE SKY COVER. ALSO HAVE BUMPED MIN TEMPS UP A FEW DEGREES WHERE
CLOUD COVER SHOULD LINGER THE LONGEST.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
TUESDAY...VERY SIMILAR TO PREVIOUS DAYS...SOME CLOUD COVER COMING 
FROM THE WEST...MAX TEMPS IN THE MID TO UPPER 30S...AROUND 40F AGAIN 
IN SELECTED LOCALES. UPSLOPE SNOW OUT WEST VERY LIGHT/FLURRIES.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
THE FIRST PART OF THE XTND FCST IS FAIRLY STR8 FORWARD. CANADIAN 
HIGH PRES WL NOSE INTO THE MID ATLC RGN - KEEPING AREA DRY AND W/ 
BLO NRML TEMPS THRU XMAS EVE. BUT THE WX LOOKS TO CHG ON XMAS EVE 
NGT/XMAS DAY. I'LL DISCUSS PSBLTIES IN THE PARAS BLO. WHILE I 
REFRAIN FM ANALOGS BECAUSE NO 2 EVENTS ARE EXACTLY ALIKE THE DAY 
THAT COMES TO MIND IS JAN 19 1996. 

**
AT IAD JAN 6-9 1996 RCVD 24.8" OF SNOW...WHICH IS GNRLY 
REPRESENTATIVE OF THE ENTIRE CWA. THERE WAS A 2ND 6" SNOWFALL ON THE 
12TH. SOME MELTING/SETTLING TOOK PLACE IN THE WK THAT FOLLOWED BUT 
ON THE 18TH IAD STILL REPORTED 9" OF WHAT WAS PRBLY A VERY HIGH 
WATER CONTENT SNOWPACK.

ON THE NGT OF THE 18TH IT RAINED AND CONTINUED THRU THE MRNG OF THE 
19TH - TOTAL WAS 0.83". MORE IMPORTANTLY IAD DWPTS OVRNGT ROSE TO 
55-60 CAUSING SNOWPACK TO MELT RAPIDLY. THE COMBO OF THE RAIN AND 
SNOWMELT LED TO BAD FLDG THRUT THE CWA IN THE FOLLOWING DAYS.
**

THIS THU NGT LOW PRES CENTERED OVER UPPER GRT LKS W/ OCCLUDED FNT 
RUNNING DOWN INTO THE MID ATLC. SYNOPTIC SITUATION LOOKS LK A WEDGE 
OF SUB 1300M 850-1000 THCKNS DVLPG ALONG E SIDE OF MTNS THU WOULD 
RESULT IN A PD OF FZRA/IP W OF THE CITIES THU NGT INTO XMAS MRNG.

FOR NOW...IT LOOKS LK WARMER AIR WOULD PUSH INTO THE SHEN VALLEY BY 
FRI AFTN. AS ALWAYS I'M LEERY OF THE SCOURING TIME OF SUB FRZG AIR 
DURG THE WINTER.

FURTHER E - IN THE MAJOR CITIES. BLV THE BULK OF THE STORM THU 
NGT/FRI WL BE LIQUID...ENHANCED FRI AFTN BY SERLY LO LVL INFLOW. 
THIS IS SUBJECT TO CHG - BUT QPF OF 1" PSBL IN CITIES. DWPTS LOOK LK 
THEY COULD RISE TO 40S XMAS DAY...SO NOT XPCTG THE SAME LVL OF MELT 
AS JAN 96.

SO FOR NOW...THESE ARE THINGS LATER SHIFTS WL NEED TO MONITOR - PTNL 
FOR ICING IN THE SHEN VALLEY THU NGT/ERLY FRI AND URBAN FLDG IN THE 
I-95 CORRIDOR. IF STORM DRAINS AREN'T CLEARED OF SNOW CITY ROADS COULD 
BECOME FLOODED.

UPSLOPE SNOWS PSBL THRUT THE WKND. TEMPERATURES SAT AND SUN AFTN WL 
SPEND MAJORITY OF TIME IN U30S E OF THE MTNS.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
MID LEVEL DECK CONTINUES TO DECREASE FOR THE TERMINAL SITES EAST OF 
THE BLUE RIDGE MOUNTAINS. AS AN UPPER LEVEL DISTURBANCE PULLS OFF TO 
THE NORTH...THE CLOUDINESS WILL CONTINUE TO DECREASE. KMRB SHOULD 
STAY CLOUDY THE LONGEST. HOWEVER...CIGS WILL REMAIN WELL ABOVE 3 
KFT. 

VFR CONDS XPCTD TUE NGT-THU. CONDS XPCTD TO DETERIORATE THU NGT
AND XMAS DAY.

&&

.MARINE...
WINDS ON THE WATERS RANGE FROM 10 TO 15 KTS. THE SCA ISN'T BEING 
REALIZED AT THIS TIME. WILL GO AHEAD AND REMOVE HEADLINE FOR THE 
REMAINING OVERNIGHT HOURS. 

NO PROBS XPCTD ON THE WATERS TUE NGT-THU.

&&

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

&&

$$
UPDATE...LISTEMAA