FXUS61 KPBZ 051509
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1009 AM EST SAT DEC 5 2009
.SYNOPSIS...
LOW PRESSURE MOVING UP THE EAST COAST WILL BRING SNOW TO MUCH
OF THE AREA TODAY. THE SYSTEM WILL EXIT THIS EVENING...WITH
HIGH PRESSURE BRINGING DRY AND COLD CONDITIONS FOR SUNDAY
INTO MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SNOW IS MOVING NORTH ACROSS THE RIDGES AND WESTERN PA...WITH SOME
LIGHT SNOW AS FAR WEST AS ZANESVILLE. WITH REPORTS OF ACCUMULATING
SNOWS ACROSS THE WESTERN PA RIDGES...HAVE EXTENDED THE WINTER
WEATHER ADVISORY NORTH TO COVER WESTMORELAND/FAYETTE/PRESTON
COUNTIES. SNOW WILL CONTINUE INTO THIS AFTERNOON AS LOW PRESSURE
MOVES UP THE EAST COAST. EXPECT TOTAL SNOW ACCUMULATIONS OF
2 TO 4 INCHES ABOVE 2000 FEET...WITH AN INCH OR SO BETWEEN 1500
AND 2000 FEET...WITH A TRACE TO A HALF INCH FOR THE LOWEST
ELEVATIONS OF SOUTHWEST PA. THE UPPER TROUGH WILL SHIFT INTO W PA
BY LATE AFTERNOON AND KICK SFC LOW FURTHER EASTWARD. THIS WILL
BRING A QUICK END TO THE SNOW FROM WEST TO EAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
EXPECT SNOW TO END IN ADVISORY AREA BY 00Z. UL FLOW WILL BECOME
ZONAL AND SFC HIGH WILL MOVE INTO THE MID ATLANTIC. CAA EXPECTED
OVERNIGHT WITH DRIER AIR SHIFTING EASTWARD. MID LEVEL WINDS REMAIN
WESTERLY OVERNIGHT SO ANY LES SHOULD BE CONFINED TO COUNTIES TO MY
NORTH.
SFC HIGH WILL PROVIDE A DRY BUT COLD DAY SUNDAY.
A WEAK COLD FRONT WILL PASS THROUGH THE AREA MONDAY. THIS WILL
BRING A CHANCE FOR RAIN/SNOW MONDAY. A BIT TOO EARLY TO DETERMINE
WHERE THE CHANGE OVER LINE WILL BE. MOISTURE IS LIMITED, SO DO NOT
EXPECT MUCH PRECIP WITH SYSTEM.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
LOW PRESSURE IS EXPECTED TO TRACK NORTHEAST THROUGH THE CENTRAL
GREAT LAKES WEDNESDAY. TRACK AND CURRENT TIMING OF THE LOW ACROSS
OHIO AS DEPICTED BY OPERATIONAL GFS, GFS ENSEMBLES, AND ECMWF
WOULD MEAN AN INITIAL WINTRY PRECIPITATION MIX FOLLOWED BY A
CHANGE TO RAIN. THE SYSTEMS COLD FRONT WOULD THEN CHANGE THE RAIN
TO SNOW ON WEDNESDAY NIGHT WITH COLD NORTHWEST FLOW CONTINUING THE
CHANCE FOR SNOW SHOWERS FOR THURSDAY. WARM FRONT AHEAD OF AN
APPROACHING LOW MAY BRING THE POTENTIAL FOR MORE SNOW ON FRIDAY.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
SNOW HAS OVERSPREAD MUCH OF THE REGION THIS MORNING...IN ASSOCIATION
WITH A LOW PRESSURE SYSTEM MOVING UP THE EAST COAST. IFR CONDITIONS
IN SNOW ARE EXPECTED ACROSS MOST AREA TERMINALS WITH THE EXCEPTION OF
FKL AND ZZV WHERE RESTRICTIONS SHOULD BE LESS. FURTHER SOUTH FOR
MGW-LBE VLIFR CONDITIONS TO NEAR ZERO VISIBILITIES CAN BE EXPECTED
FOR A FEW HOURS INTO EARLY AFTERNOON IN SNOW. AS THE LOW PULLS
FURTHER NORTHEAST CONDITIONS WILL INCREASE RAPIDLY LATER THIS
AFTERNOON INTO EARLY EVENING.
HIGH PRESSURE COMING FROM THE MIDWEST WILL PROVIDE VFR ACROSS THE
UPPER OHIO VALLEY TONIGHT INTO EARLY MONDAY. THEN A LOW PRESSURE
SYSTEM MOVING EASTWARD THROUGH THE GREAT LAKES CAN PROVIDE A PERIOD
OF MVFR RAIN AND SNOW SHOWERS LATE MONDAY INTO TUESDAY. A STRONG LOW
PRESSURE SYSTEM COMING FROM OKLAHOMA CAN BRING IFR SNOW AND RAIN TO
THE UPPER OHIO VALLEY WEDNESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR PAZ030-
032.
WV...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR WVZ023-
041.
&&
$$
