FXUS61 KPBZ 150553
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1253 AM EST TUE DEC 15 2009
.SYNOPSIS...
SCATTERED SHOWERS CAN BE EXPECTED AS A COLD FRONT MOVES THROUGH
TONIGHT. COLDER TEMPERATURES WILL RETURN FOR THE REST OF THE WORK
WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
LOW PRESSURE WILL PUSH ACROSS THE EASTERN GREAT LAKES LATE TONIGHT.
A COLD FRONT WILL THE SYSTEM WILL PUSH ACROSS THE DISTRICT TOWARD
DAYBREAK BRINGING A CHANCE OF SHOWERS OVERNIGHT. AFTER THE COLD
FRONT MOVES THROUGH...FALLING TEMPERATURES WILL OCCUR...WITH THE
HIGH TEMPERATURE ON TUESDAY LIKELY OCCURRING TOWARD DAYBREAK IN MOST
LOCATIONS. WHILE PRECIPITATION SHOULD REMAIN IN THE FORM OF RAIN
OVERNIGHT...ANY PRECIPITATION LEFT OVER ON TUESDAY WILL EVENTUALLY
CHANGE OVER TO SNOW SHOWERS. WITH WEST- NORTHWESTERLY FLOW BEHIND THE
FRONT...LOCATIONS ALONG THE RIDGES AND NORTH OF I-80 WILL BE
FAVORED LOCATIONS FOR ANY MEASURABLE SNOWFALL LATE TUESDAY.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL DOMINATE THE WEATHER FOR WEDNESDAY AND THURSDAY.
AS THE HIGH MOVES FROM THE CENTRAL PLAINS ON WEDNESDAY TO OUR AREA
ON THURSDAY...EXPECT NORTHWESTERLY FLOW AND LAKE EFFECT SNOW SHOWERS
TO BE ON THE DECREASE. NAM/GFS AGREE THAT THERE COULD BE AN UPPER
LEVEL SHORTWAVE SLIGHTLY INTENSIFYING ANY LEFT OVER SNOW SHOWERS ON
WEDNESDAY. TEMPERATURES WILL BE 5-10 DEGREES BELOW NORMAL DURING THE
TIME PERIOD.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
JUDGING FROM RECENT GEFS AND ECMWF MODEL OUTPUT A STRONG UPPER LEVEL
LOW CENTER WILL DEVELOP OVER EASTERN CANADA THIS PERIOD...AND IT
APPEARS ONE OF ITS SHORTWAVE LOBES WILL MOVE SOUTHWARD THROUGH THE
GREAT LAKES. IN ACCORDANCE WITH HPC GUIDANCE...THIS SHOULD INDUCE A
TREND TOWARD COLDER TEMPERATURES ACROSS THE UPPER OHIO VALLEY THIS
PERIOD. WITH SURFACE LAYER WINDS GENERALLY FROM THE NORTH...THERE IS
AN INCREASING CHANCE OF LAKE EFFECT AND OROGRAPHICALLY ENHANCED
INSTABILITY SNOW SHOWERS TOWARD MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
A COLD FRONT WILL CROSS THE TERMINALS DURING THE PRE-DAWN HOURS
THIS MORNING WITH SOUTHWESTERLY WINDS BECOMING MORE WESTERLY AND
CEILINGS LOWERING TO MVFR. A FEW LIGHT RAIN SHOWERS OR DRIZZLE WILL
BE POSSIBLE FOR BRIEF PERIODS AT KDUJ/KFKL WITH MVFR VISIBILITIES.
BEHIND THE COLD FRONT...CEILINGS WILL DROP TO NEAR IFR ACROSS THE
TERMINALS THIS MORNING...SLOWLY RISING BACK TO AROUND 2KFT IN THE
AFTERNOON. WITH A NORTHWESTERLY FLOW AND COLD AIR ADVECTION...SOME
LAKE EFFECT SNOW SHOWERS WILL BE POSSIBLE LATE THIS
AFTERNOON...WITH THE BEST CHANCE OF SNOW SHOWERS WITH REDUCED
VISIBILITIES NORTH OF KPIT.
MVFR CEILINGS TUESDAY NIGHT WILL BECOME VFR AND CLOUD COVERAGE
WILL BEGIN TO DIMINISH WEDNESDAY MORNING AS LOW-LEVEL MOISTURE
ADVECTS NORTHEAST OF THE AREA AND HIGH PRESSURE BUILDS IN FROM THE
WEST. HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA LATE THIS
WEEK WITH MOSTLY VFR CONDITIONS EXPECTED THROUGH SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
