FXUS61 KPBZ 282036
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
336 PM EST SAT NOV 28 2009
.SYNOPSIS...
HIGH PRESSURE ACROSS THE AREA WILL BRING DRY WEATHER THROUGH
SUNDAY. A COLD FRONT WILL APPROACH FROM THE WEST SUNDAY
NIGHT...RETURNING SHOWERS TO THE AREA BY MONDAY MORNING. THE
CHANCE FOR SHOWERS WILL CONTINUE THROUGH MONDAY NIGHT...WITH
PRECIPITATION CHANGING OVER TO SNOW BY TUESDAY MORNING.
&&
.NEAR TERM /THROUGH SUNDAY/...
HIGH PRESSURE WILL CONTINUE TO DOMINATE THE FCST OVERNIGHT WITH
RIDGING BUILDING IN ACROSS THE AREA. THIS WILL ALLOW FOR CLEAR
SKIES ALONG WITH LIGHT SWRLY WINDS. SOME RADITIONAL COOLING WILL
OCCUR OVERNIGHT...AS THE CORE OF COOLEST TDS ADVECTS ACROSS THE
AREA. MAV/MET GUIDANCE SEEM TO BE TRENDING A FEW DEGREES WARM ON
TDS OVERNIGHT...AND AM EXPECTING TDS TO RADIATE DOWN
SOMEWHAT...WITH FCST LOWS BELOW AROUND 3-5 DEGREES BELOW GUIDANCE
TONIGHT.
SUNDAY...A SFC LOW IS PROGGED TO BE ACROSS MICHIGAN WITH ITS ASSOCD
COLD FRONT EXTENDING SWWD ACROSS THE MO VALLEY FOR SUNDAY MORNING.
AHEAD OF THE COLD FRONT...FLOW ALOFT WILL BECOME MORE ZONAL EARLY. A
FRONTAL BOUNDARY WILL LIFT NWD ACROSS THE AREA SUNDAY AFTN. THIS
WILL ALLOW FOR MORE SRLY WINDS AND WAA TO PROVIDE AN UNSEASONABLY
WARM DAY...WITH HIGHS AROUND 10 DEGREES ABOVE NORMAL. CLOUDS SHOULD
BE INCREASING FROM THE NW AS SOME WEAK ISENTROPIC LIFT WORKS IN FROM
THE WEST.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
A COLD FRONT WILL APPROACH FROM THE WEST...WITH THE AREA IN WAA WITH
A SRLY FLOW AHEAD OF THE FRONT ON SUNDAY NIGHT. CHC POPS FCST TO
BEGIN AFTER 00Z WITH SHOWERS LIKELY BY 12Z AS THE COLD FRONT NEARS
THE AREA. MET/SREF BLEND APPEAR TO BE ACCOUNTING FOR WARMER TEMPS
FOR SUNDAY NIGHT WHICH SEEMS REASONABLE.
GFS/NAM ARE IN AGREEMENT WITH THE FRONT PROGGED TO BE CROSSING THE
CWA AROUND 12Z MON. 500MB TROF WITH THE SYSTEM WILL BE FAIRLY BROAD
WITH MORE OF A WRLY FLOW MONDAY NIGHT AND CAA CONTINUING WITH A
NWRLY FLOW ON TUESDAY. TEMPS WILL BE FAIRLY STEADY MONDAY IN THE
LOWER TO MID 40S AS THE FRONT MOVES THROUGH AND DROPPING OFF QUICKLY
MONDAY NIGHT INTO THE UPPER 20S TO LOWER 30S. TEMPS ON TUESDAY WILL
BE NEAR NORMAL VALUES WITH CLOUD COVERAGE IN A NWRLY FLOW.
PRECIP WILL BE FOCUSED IN TWO PHASES. THE FIRST SHOT WILL BE WITH THE
FRONTAL PASSAGE EARLY MONDAY. THE SECOND WILL BE ALONG AND BEHIND
THE H5 TROF AXIS IN THE MOIST NWRLY FLOW WHICH WILL GENERATE
POST-FRONTAL LAKE EFFECT SHOWERS MONDAY NIGHT AND EARLY TUESDAY. ON
THE BACK EDGE OF THE FRONT...SNOW WILL MIX IN WITH RAIN SHOWERS.
WITH THICKNESSES CONTINUING TO DECREASE WITH THE TROF AXIS
CROSSING THE AREA...PRECIPITATION SHOULD BECOME MOSTLY SNOW ACROSS
THE AREA BY THE TIME LAKE EFFECT KICKS IN OVERNIGHT INTO TUESDAY
MORNING. LAKE EFFECT ZONES AND THE UPSLOPING ACROSS THE EASTERN
RIDGES WILL BE MORE CONDUCIVE TO ANY ACCUMULATION. AT THE
MOMENT...SREF PROBS ARE NOT HITTING ON SIGNIFICANT ACCUMULATIONS
FOR THESE AREAS...ALTHOUGH GFS/NAM ARE INDICATING THE POSSIBILITY
OF ACCUMULATION TUESDAY MORNING.
ON TUESDAY...HIGH PRESSURE WILL BUILD IN FROM THE SOUTH WITH
LINGERING SNOW SHOWERS DIMINISHING ACROSS THE RIDGES AND LAKE
EFFECT ZONES DURING THE DAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
INTERESTING PATTERN FOR MID TO LATE WEEK WITH SOUTHERN STREAM ENERGY
KICKING OUT IN ADVANCE OF NORTHERN STREAM TROF DIGGING INTO THE
GREAT LAKES. NOT THAT FAR OFF OF HPC PROGS ALTHOUGH DID GO A BIT
COLDER FOR THURSDAY AND BROUGHT THE PRECIP SWITCH OVER TO SNOW BY
LATE DAY. LATEST ECMWF AND GFS LOOKING COLDER FOR LATE WEEK INTO
NEXT WEEKEND AND WENT NEAR OR A BIT BELOW HPC GUIDANCE.
&&
.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
HIGH PRESSURE ACROSS WEST VIRGINIA WILL MOVE EAST THROUGH SUNDAY
WITH VFR CONDITIONS PREVAILING ACROSS THE TERMINALS.
A COLD FRONT WILL CROSS THE REGION MONDAY MORNING BRINGING THE
NEXT CHANCE FOR REDUCED CONDITIONS INTO MONDAY. VFR IS THEN
EXPECTED AGAIN FOR MONDAY NIGHT INTO TUESDAY. A SYSTEM MOVING
NORTHEAST UP THE COAST WILL BRING THE NEXT POTENTIAL FOR REDUCED
CONDITIONS WEDNESDAY AND THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
