000
FXUS61 KPBZ 200742
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
242 AM EST THU NOV 20 2008
.SYNOPSIS...
AS A LOW PRESSURE SYSTEM MOVES SOUTHEAST TOWARD NEW ENGLAND...A
COLD FRONT WILL CROSS THE DISTRICT THIS MORNING. THIS WILL USHER
IN A COLDER AIRMASS...AND AN EXTENDED PERIOD OF LAKE EFFECT SNOW
FOR TONIGHT THROUGH FRIDAY NIGHT.
&&
.NEAR TERM /THROUGH TODAY/...
THE COLD FRONT...JUST EAST OF CLE AT 7Z WILL CROSS THE CWA EARLY
THIS MORNING. SNOW SHOWER ACTIVITY WILL FOLLOW IN UNSTABLE AIRMASS
BEHIND THIS FRONT.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
LAKE EFFECT SNOW SHOWERS WILL START IN EARNEST THIS EVENING...AS
THE COLDER AIR PUSHES SOUTH...AND FLOW TURNS MORE NORTH TO
NORTHWEST. THIS SCENARIO WILL CONTINUE RIGHT THROUGH FRIDAY 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 /07Z THURSDAY THROUGH MONDAY/...
A COLD FRONT WILL PUSH ACROSS THE FORECAST AREA TODAY KEEPING
OVERCAST STRATOCU WITH CEILINGS OF 025-035 FEET THIS MORNING. THE
CEILINGS WILL SLOWLY LOWER THIS AFTERNOON 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 CONDITONS 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.
&&
$$
LS
