Winter Storm in Virginia, January 19, 2002

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE WAKEFIELD, VA
725 AM EST SAT JAN 19 2002

MASSAGED SNOW AMOUNTS DOWNWARD FEW ZONES...AND PTYPE CHANGE TIMING A
LITTLE WITH UPDATE. PAST FEW HOURS HAVE NOTED INCREASE IN SFC WET
BULB ACROSS THE SOUTHEAST...WITH TEMPS RISING FROM 25F TO 34F SINCE
MIDNIGHT HERE AT THE OFFICE. DEWPTS HAVE LIKEWISE RISEN. THIS SFC
WARMING...AND EXPECTED WARMING ALFT SHOULD LIMIT SNOW AMOUNTS OVER
ALL BUT THE NW COUNTIES. GOING FCST STILL LOOKS REASONABLE...
ALTHOUGH ICING POTENTIAL OVER SRN PORTIONS OF THE WARNED AREA
SOMEWHAT IN DOUBT. ALSO...NOTED THUNDERSNOW AT BECKELEY AN HOUR AGO.
WELL SEE WHAT HAPPENS WHEN STG DYNAMICS AND MODERATE TO HEAVY PRECIP
WORK ITS WAY INTO OUR AREA AS FAR AS PTYPE IS CONCERNED.  PREVIOUS
AFD INCLUDED BELOW.
*****************************************************************

PRECIP NOW ON OUR DOORSTEP...WITH SNOW FALLING ACROSS MUCH OF
KY...AND A COLD RAIN ACROSS TENNESSEE...WITH SOME FREEZING RAIN NR
THE BORDER. THIS BAND OF RAIN IS PROGGED TO MOVE QUICKLY EWD TODAY
ACROSS OUR CWA. UVV FORCED PRIMARILY BY LOW LEVEL WAA...WITH
IMPRESSIVE VERTICAL MOTIONS DUE TO MOVE QUICKLY FROM W TO E ACROSS
THE AREA TODAY.

PRECIP TYPE AND AMT TODAY ARE THE MAIN FORECAST PROBLEMS. SFC LOW
PROGGED TO PASS THROUGH N CAROLINA TODAY...AND OFF NE NC BY THIS
EVENING. 850 MB LOW TO PASS TO OUR NW...ALLOWING WARMER AIR...AND
STG WAA...TO MOVE IN AT THAT LEVEL. PRECIPITATION TO FALL INTO AN
INITIALLY DRY AMS...WITH SFC WETBULBS GENERALLY BELOW
FREEZING...EXCEPT FOR SE ZONES WHERE ABOVE. 06 SOUNDING FROM ROANOKE
SHOWS JUST HOW DRY LOWER LAYERS ARE...AND THE POTENTIAL FOR COOLING
BELOW THE WET BULB AT THE ONSET OF PRECIP.

BASED ON PARTIAL THICKNESS SCHEMES AND MODEL SOUNDINGS...STILL
EXPECT MAINLY RAIN SE ZONES...RAIN...CHANGING TO SNOW ACROSS THE ERN
SHORE AND MUCH OF S CENTRAL VA...AND PERHAPS SEVERAL HOURS OF SNOW
ACROSS NW ZONES...OUT TOWARD LOUISA AND FLUVANNA COUNTIES...BEFORE
POSSIBLY CHANGING TO SLEET OR FREEZING RAIN. PLACES LIKE FARMVILLE
WILL SEE LESS SNOW...BUT FREEZING RAIN MAY BE MORE OF A PROBLEM...AS
SFC TEMPS INITIALLY STRUGGLE TO RISE ABOVE FREEZING.

JUST HOW QUICKLY THESE PHASE CHANGES OCCUR WILL BE DEPENDENT ON THE
CHANGING THERMAL STRUCTURE...WHICH IS COMPLICATED BY STG WAA...BEING
BALANCED AT LEAST INITIALLY BY EVAP COOLING. EVENTUALLY...WAA WILL
WIN OVER ALL BUT OUR NW PIEDMONT COUNTIES...BUT BEFORE CHANGEOVER
OCCURS...COULD SEE BURST OF MDT TO HEAVY SNOW N OF THE R/S LINE.

BOTTOM LINE...WILL MAKE ONLY MINOR ADJUSTMENTS TO GOING FCAST...WITH
SLIGHT ADJUSTMENTS TO SNOW AMTS...BUT WILL LEAVE WARNINGS AND
ADVISORIES AS IS.

OTHER POSSIBLE PRECIP CHCS LOOK TO BE SUN NIGHT...WITH WEAK FAST
MOVING SYSTEM JUST A SLIGHT CHC...THEN MOVE SIGNIFICANT STORM BY THU
(PERHAPS STARTING WED). NO CHANGES TO EXTENDED AT THIS POINT...AS
CHCS SUN NIGHT REMOTE AT THIS POINT. DAY SHIFT CAN REEVALUATE.

FCSTID = 18
SBY   39  28  45  32 / 100  50   0  10
OXB   39  28  45  32 / 100  50   0  10
ECG   49  34  49  35 / 100  60   0  10
ORF   43  33  48  34 / 100  50   0  10
PHF   37  28  47  32 / 100  50   0  10
AKQ   37  28  47  32 / 100  50   0  10
RIC   35  27  46  30 / 100  30   0  10
FVX   34  27  47  30 / 100  30   0  10

.AKQ...
MD...WINTER WEATHER ADVISORY FOR SATURDAY FOR ZONE MDZ021. SCA ATLC
COASTAL WATERS.
NC...SCA...ATLC COASTAL WATERS N OF CURRITUCK BEACH LIGHT.
VA...WINTER STORM WARNING FOR SATURDAY FOR ZONES
VAZ048>049...VAZ060>064...VAZ066...VAZ069.
SCA...ATL COASTAL WATERS AND CHES BAY S OF NEW PT COMFORT.

WINTER WEATHER ADVISORY FOR SATURDAY FOR ZONES VAZ065...VAZ067>068...
VAZ070>076...VAZ082>083.

REILLY