FXUS61 KPBZ 260310
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1010 PM EST FRI DEC 25 2009

.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM OVER THE MIDWEST WILL MOVE SLOWLY
NORTHEASTWARD ACROSS THE GREAT LAKES THIS WEEKEND AND PUSH A COLD
FRONT THROUGH THE UPPER OHIO VALLEY SATURDAY MORNING. THERE CAN BE
ISOLATED SHOWERS SATURDAY FOLLOWED BY SCATTERED SNOW SHOWERS
SUNDAY INTO TUESDAY. 

&&

.NEAR TERM /THROUGH SATURDAY/...
BASED ON RECENT RADAR DATA AND SREF MODEL OUTPUT...REDUCED
COVERAGE OF PRECIPITATION ACROSS THE UPPER OHIO VALLEY OVERNIGHT
AND SATURDAY. WIND GUSTS NEAR THE MOUNTAINS SHOULD BE SUBSIDING
LATE TONIGHT. AREAS OF FOG AND POCKET OF FREEZING DRIZZLE CAN
PERSIST ACROSS THE WEST VIRGINIA AND MARYLAND MOUNTAINS.

FORECASTED TEMPERATURES USING A BLEND OF GFS MOS AND SREF MODEL
OUTPUT.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
JUDGING FROM RECENT SREF MODEL OUTPUT IT STILL APPEARS THAT
PROBABILITY OF INSTABILITY SNOW SHOWERS RELATED WITH THE EASTWARD
PASSAGE OF A COLD UPPER LOW CENTER THROUGH THE GREAT LAKES WILL
NOT INCREASE TO LIKELY UNTIL SUNDAY AFTERNOON AND SUNDAY NIGHT.
THIS CAN RESULT IN A SMALL SNOW ACCUMULATION SUNDAY NIGHT INTO
MONDAY. 

FORECASTED TEMPERATURES USING A BLEND OF RECENT GFS MOS AND SREF
MODEL OUTPUT.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS UPPER LOW CENTER EXITS EASTWARD TO NEW ENGLAND...EXPECT SNOW
SHOWERS TO WIND DOWN MONDAY NIGHT. 

SURFACE HIGH PRESSURE WILL BUILD INTO THE REGION TUESDAY AND
WEDNESDAY BRINGING DRY WEATHER. A LOW PRESSURE SYSTEM OVER THE
SOUTHEASTERN STATES WILL BRING MOISTURE AND A CHANCE OF SNOW
SHOWERS TO THE THE FORECAST AREA FOR WEDNESDAY NIGHT INTO THURSDAY.
ANOTHER WEAK SHORT WAVE WILL BRING MORE SNOW SHOWERS FOR FRIDAY.

CLOUD COVER WILL HOLD DAYTIME TEMPERATURES DOWN TO FEW DEGREES BELOW 
NORMAL THROUGH THE EXTENDED PERIOD.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
A STRONG LOW PRESSURE SYSTEM WILL REMAIN ACROSS THE MIDWEST...WITH A 
FEW ASSOCIATED SHOWERS MOVING ACROSS THE TERMINALS OVERNIGHT.  
SOUTHEAST WINDS WILL SHIFT TO SOUTHWEST AND GUST TO AROUND 25 KTS. 
THE WIND SHIFT WILL OCCUR FIRST AROUND 03Z AT KZZV...REACHING KPIT 
AROUND 08Z...AND FINALLY KDUJ/KFKL BY DAWN. CEILINGS WILL BECOME
MVFR ACROSS MOST OF THE TERMINALS AND MAY DROP TO IFR AT TIMES
OVERNIGHT. IFR CEILINGS WILL BE MORE LIKELY TO PREVAIL AT
KFKL/KDUJ.

LOW-LEVEL WIND SHEAR WILL CONTINUE TO BE POSSIBLE ACROSS
THE TERMINALS THIS EVENING...WITH A LOW-LEVEL JET EXITING
NORTHEAST OF THE AREA AND LLWS DIMINISHING BY 09Z ACROSS THE TAF
SITES.

HIGH PRESSURE WILL BUILD IN FROM THE SOUTH ON SATURDAY...WITH
CEILINGS BECOMING VFR BY LATE MORNING ACROSS THE AREA. THERE IS
THE CHANCE FOR A FEW SNOW SHOWERS ACROSS THE NORTHERN
TERMINALS ON SATURDAY...ALTHOUGH CONFIDENCE IS NOT HIGH ENOUGH TO
MENTION IN THE TAFS AT THE MOMENT. AN UPPER LEVEL LOW WILL
ADVECT INTO THE EASTERN GREAT LAKES ON SUNDAY AND INTO THE
NORTHEAST ON MONDAY. THIS WILL ALLOW FOR THE POSSIBILITY OF SNOW
SHOWERS WITH REDUCED CEILINGS AND VISIBILITIES. HIGH PRESSURE WILL
BUILD INTO THE AREA LATE ON TUESDAY...WITH VFR CONDITIONS
PREVAILING INTO WEDNESDAY.

&&

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

&&

$$