FXUS61 KPBZ 221429
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
929 AM EST TUE DEC 22 2009
.SYNOPSIS...
SCATTERED SNOW SHOWERS ARE POSSIBLE TODAY. HIGH PRESSURE
BUILDING INTO THE DISTRICT THIS AFTERNOON WILL BRING COLD AND DRY
CONDITIONS FOR TONIGHT INTO THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
MORNING UPDATE TO THE FORECAST INCREASES THE CHANCE OF SNOW IN ALL
LOCATIONS TODAY. ONE AREA OF SNOW IS DEVELOPING ACROSS OHIO AND
PUSHING TO THE EAST...WHILE A SECOND AREA OF SNOW IS MOVING OFF
LAKE ERIE INTO THE I-80 CORRIDOR. ONCE UPPER LEVEL SUPPORT MOVES
EAST OF THE AREA THIS AFTERNOON..EXPECT PRECIPITATION TO DIMINISH.
SNOW ACCUMULATION SHOULD BE NO MORE THAN AN INCH. SOME PATCHY
FREEZING DRIZZLE MAY ALSO BE POSSIBLE...PARTICULARLY IN THE
RIDGES...WITH CLOUD TOPS NOT NECESSARILY COLD ENOUGH TO SUPPORT
GROWTH OF SNOW CRYSTALS. HOWEVER...COVERAGE IS NOT EXPECTED TO BE
WIDESPREAD ENOUGH TO SPECIFICALLY INCLUDE IN THE FORECAST - HAVE
COVERED THIS WITH AN SPS. HIGH PRESSURE BUILDING INTO THE DISTRICT
THIS AFTERNOON WILL BRING DRY WEATHER TONIGHT.
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
HIGH PRESSURE WILL BRING DRY WEATHER FOR WEDNESDAY AND WEDNESDAY
NIGHT.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
ON THURSDAY A POWERFUL STORM DEVELOPS IN THE NATIONS MID
SECTION WITH MOISTURE STREAMING INTO THE REGION BY LATE DAY. FOR
NOW IT APPEARS ANY PRECIP THAT ARRIVES LATE DAY WILL START AS
RAIN. THE MIDWEST STORM WILL MOVE SLOWLY EAST ACROSS THE CENTRAL
PLAINS THURSDAY NIGHT WITH A BROAD AREA OF LIFT AHEAD OF THIS
SYSTEM BRINGING MIXED PRECIPITATION TO THE AREA BY THURSDAY NIGHT.
SNOWPACK AND ELEVATION WILL BE MORE CONDUCIVE FOR SUBFREEZING
GROUND TEMPS TO LINGER OVERNIGHT ACROSS THE EASTERN RIDGES...WITH
THE POTENTIAL FOR A FREEZING RAIN EVENT THERE THROUGH CHRISTMAS
MORNING. TEMPS WILL BE AROUND 5 DEGREES ABOVE NORMAL ON
CHRISTMAS...WITH WARM AIR ADVECTION AND LIKELY POPS CONTINUING
THROUGHOUT THE DAY.
ON CHRISTMAS NIGHT THE UPPER LEVEL LOW WILL LIFT NORTHEASTWARD INTO
THE UPPER GREAT LAKES AND A COLD FRONT WILL CROSS THE AREA. FORECAST
IS CLOSER TO A GFSE/HPC SOLUTION...ALTHOUGH THE 12Z ECMWF TRENDS
EVEN SLOWER WITH THE ARRIVAL OF THE FRONT. WITH THE PASSAGE OF THE
FRONT...PRECIPITATION WILL TURN OVER TO ALL SNOW BY SATURDAY MORNING
WITH COLD AIR ADVECTION THROUGH THE DAY. WITH THE TROUGH AXIS
CROSSING THE AREA THROUGH MONDAY...THE CHANCE OF SNOW SHOWERS ACROSS
THE AREA WILL CONTINUE. FORECAST HIGH TEMPERATURES WILL BE AROUND 5
DEGREES BELOW NORMAL THROUGH THE WEEKEND INTO MONDAY.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
MVFR WILL PERSIST THROUGH THIS AFTN...AS UPPER LEVEL LOW PRESSURE
CROSSES THE NORTHERN GREAT LAKES. SCATTERED SNOW SHOWERS WILL CLIP
NORTHERN TERMINALS FKL/DUJ THROUGH MID/LATE MORNING WITH AREAS OF
IFR...WITH ISOLATED SNOW SHOWERS FURTHER SOUTH. CONDITIONS WILL
IMPROVE TO VFR BY THIS EVENING AS THE LOW EXITS TO THE NORTHEAST.
LIGHT W/SW WINDS OVERNIGHT WILL BECOME N/NW 5-8 KT THIS AFTN.
HIGH PRESSURE WILL BUILD OVER THE REGION FOR WEDNESDAY INTO THURSDAY
WITH VFR CONDITIONS CONTINUING. LOW PRESSURE WILL APPROACH FROM THE
SOUTHWEST BY THURSDAY NIGHT CROSSING THE AREA CHRISTMAS DAY BRINGING
PRECIPITATION/RESTRICTIONS AREA WIDE. THERMAL PROFILES SUGGEST
MAINLY RAIN FOR MOST AREAS WITH SOME CHANCE FOR FREEZING RAIN AT
PORTS FKL/DUJ THURSDAY NIGHT THROUGH CHRISTMAS MORNING. RESTRICTIONS
WILL PERSIST FRIDAY NIGHT AND SATURDAY WITH PRECIPITATION CHANGING
TO SNOW.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
