FXUS61 KPBZ 150004
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
704 PM EST MON DEC 14 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 TUESDAY/...
LOW PRESSURE NEAR CHICAGO WILL MOVE TO THE NORTHEAST...MOVING ACROSS 
THE EASTERN GREAT LAKES. CURRENTLY...THE COLD FRONT IS NOT PRODUCING 
MUCH OF ANY PRECIPITATION...WHICH DECREASES CONFIDENCE IN THE CHANCE 
THAT THERE WILL BE MEASURABLE RAINFALL ONCE THE FRONT REACHES OUR 
AREA. AT THIS POINT...WILL STICK WITH LOW CHANCE POPS THAT HAVE BEEN 
IN THE FORECAST. AFTER THE COLD FRONT MOVES THROUGH...FALLING 
TEMPERATURES WILL OCCUR...WITH THE HIGH TEMPERATURE ON TUESDAY 
LIKELY OCCURRING AT MIDNIGHT 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. WITH 
WEST-NORTHWESTERLY FLOW BEHIND THE FRONT...LOCATIONS ALONG THE 
RIDGES AND NORTH OF I-80 WILL BE FAVORED LOCATIONS FOR ANY 
MEASURABLE SNOWFALL.

&&

.SHORT TERM /TUESDAY NIGHT 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 /00Z TUESDAY THROUGH SATURDAY/...

CIGS WILL LOWER TO MVFR BY AROUND 04Z THIS EVENING...AS A COLD FRONT
APPROACHES. THIS FRONT WILL REACH WESTERN PORTS AROUND
6Z...PASSING EAST OF THE REGION BY 09Z. CIGS WILL LOWER INTO THE
IFR TO MVFR RANGE ALONG AND BEHIND THIS FRONT. A FEW SPOTTY
SHOWERS WILL ALSO BE POSSIBLE WITH THE FRONT. 

FOR TUESDAY...PREVAILING MVFR IS EXPECTED WITH A FEW WIND GUSTS TO
AROUND 20 KNOTS POSSIBLE. A BRIEF PERIOD OF IFR WILL BE POSSIBLE
FKL/DUJ IN SNOW SHOWERS.

CONDITIONS WILL IMPROVE TO VFR TUESDAY NIGHT AND CONTINUE THROUGH
WEDNESDAY AS A HIGH PRESSURE RIDGE BUILDS NORTHEAST...EXCEPT
FKL/DUJ WHERE LAKE EFFECT CLOUDS AND SNOW SHOWERS COULD LEAD TO
OCCASIONAL LOWER CONDITIONS. 

PREVAILING VFR CONDITIONS ARE THEN EXPECTED FOR THURSDAY THROUGH
SATURDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$