000
FXUS61 KPBZ 201619
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1119 AM EST THU NOV 20 2008
.SYNOPSIS...
AS A LOW PRESSURE SYSTEM MOVES SOUTHEAST TOWARD NEW ENGLAND A
COLD FRONT WILL MOVE EAST OF THE REGION THIS AFTERNOON. THIS WILL
BRING ANOTHER VERY COLD AIR MASS ACROSS THE GREAT LAKES WITH AN EXTENDED
PERIOD OF LAKE EFFECT SNOW FOR TONIGHT THROUGH FRIDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
COLD FRONT HAS MOVED EAST OF RIDGES WITH SNOW SHOWER ACTIVITY THIS
AFTERNOON BECOMING MORE LAKE ENHANCED TONIGHT WITH NORTHWEST FLOW
AND 850MB TEMPERATURES FALLING TO -14C TOWARD MORNING.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
COLD NORTHWEST FLOW SCENARIO WILL REMAIN IN PLACE INTO FRIDAY
NIGHT WITH REINFORCING TROUGHS PASSING THROUGH THE FLOW. WITH A
COLDER AIRMASS THAN WE HAD WITH THE SYSTEM EARLY THIS
WEEKEND...NOT MUCH IF ANY MELTING OF SNOW EXPECTED THROUGH THIS
UPCOMING PERIOD. THEREFORE...ACCUMULATION RATES HIGHER. ALSO...THE
DURATION OF THIS PATTERN IS LONGER. THE FLOW WILL TURN MORE FROM
THE WEST/NORTHWEST FRIDAY NIGHT...LIMITING THE LAKE EFFECT SNOW.
ORAGRAPHIC ENHANCEMENT WILL LEAD TO HIGHEST AMOUNTS OVER THE
SOUTHEAST RIDGES...WHERE A FEW LOCALITIES COULD ACCUMULATE OVER A
FOOT. WILL TURN THE CURRENT WATCH AREAS INTO WARNINGS...AND ADD AN
ADVISORY IN THE AREAS IN BETWEEN.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
BLEND OF RECENT GFS ENSEMBLE/GEFS/ MODEL RUNS SHOW THE NEXT
CLIPPER TYPE LOW PRESSURE SYSTEM AFFECTING THE UPPER OHIO VALLEY
AROUND MONDAY. SO THE WEEKEND APPEARS DRY WITH THE NEXT POTENTIAL
PRECIPITATION EPISODE AROUND MONDAY. FORECASTED TEMPERATURES WERE
CLOSE TO GFS MOS AND HPC GUIDANCE WHICH CONTINUE TEMPERATURES AS
COLDER THAN NORMAL INTO MIDWEEK.
&&
.AVIATION /16Z THURSDAY THROUGH MONDAY/...
CEILINGS WILL SLOWLY LOWER THIS AFTERNOON BEHIND COLD FRONT INTO
TONIGHT AS COLD ADVECTION AND LAKE EFFECT SNOW SHOWERS SET UP
BEHIND THE FRONT. MVFR CIGS WILL BE WIDESPREAD TONIGHT AND AREAS
OF IFR/LIFR CIGS AND VSBY EXPECTED IN SNOW SHOWERS ESPECIALLY LATE
TONIGHT INTO FRIDAY. SOME WIDELY SCATTERED SNOW SHOWERS ARE
POSSIBLE THIS AFTERNOON BUT THE SHOWERS WILL BE MORE WIDESPREAD
TONIGHT AND FRIDAY. IFR CONDITIONS MAY BE EXPECTED FRIDAY WITH THE
SNOW SHOWERS...ESPECIALLY AT FKL AND DUJ.
HIGH PRESSURE IS PROGGED TO BUILD INTO THE DISTRICT FOR SATURDAY AND
SUNDAY...WITH MAINLY VFR CONDS EXPECTED. NEXT CHANCE FOR LOWER
FLIGHT CONDITIONS WILL COME WITH THE APPROACH AND PASSAGE OF A COLD
FRONT EARLY NEXT WEEK.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM EST FRIDAY
FOR MDZ001.
OH...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST
FRIDAY FOR OHZ041.
PA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM EST
FRIDAY FOR PAZ013>016-020>023.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM EST FRIDAY
FOR PAZ030-032.
LAKE EFFECT SNOW WARNING FROM 6 PM THIS EVENING TO 6 PM EST
FRIDAY FOR PAZ007>009.
WV...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM EST FRIDAY
FOR WVZ023-041.
&&
$$
