FXUS61 KPBZ 261759
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1259 PM EST SAT DEC 26 2009

.SYNOPSIS...
HIGH PRESSURE WILL BUILD IN FROM THE SOUTH TODAY WITH SKIES CLEARING
AND DRY WEATHER EXPECTED THROUGH TONIGHT. AN UPPER LEVEL LEVEL LOW
WILL CROSS THE GREAT LAKES SUNDAY AND RETURN SNOW SHOWERS TO THE
AREA LATE SUNDAY INTO EARLY MONDAY.

&&

.NEAR TERM /THROUGH SUNDAY/...
16Z RUC 500MB ANALYSIS INDICATES A DEEP CLOSED LOW CENTERED ACROSS
WISCONSIN WITH A TROUGH AXIS EXTENDING SOUTHWEST OF THE FEATURE
INTO THE CENTRAL PLAINS. LOCALLY...DRY AIR AT THE MID-LEVELS IS
CONTINUING TO ADVECT ACROSS THE AREA...WITH A SOUTHWESTERLY FLOW
ALOFT. AT THE SURFACE...A 1001 MB SURFACE LOW IS LOCATED ACROSS
IOWA WITH A 1010MB LOW OFF THE NC/VA COAST. A BROAD AREA OF HIGH
PRESSURE IS BUILDING INTO THE SOUTHEAST FROM THE GULF OF MEXICO.
LOW-LEVEL MOISTURE IS ADVECTING NORTHEAST OF THE AREA...WITH
A FEW LINGERING SNOW SHOWERS ALONG AND NORTH OF THE INTERSTATE 80
CORRIDOR. A DEEPER LAYER OF DRY AIR IS BUILDING IN FROM THE
SOUTHWEST...WITH CLEARING SKIES FROM THE WEST.

THIS AFTERNOON AND TONIGHT...DRY AIR ADVECTING INTO THE REGION WILL
CONTINUE TO DEEPEN AS HIGH PRESSURE PASSES SOUTH OF THE AREA.
LINGERING FLURRIES WILL DIMINISH ALONG THE INTERSTATE 80 CORRIDOR.
SKIES WILL BECOME MOSTLY SUNNY THIS AFTERNOON WITH THE AREA IN A
DRY SLOT. CLEARING WILL ALLOW TEMPS TO RECOVER TODAY SOMEWHAT
DESPITE COLD AIR ADVECTION...WITH HIGHS NEAR NORMAL VALUES TODAY.
SKIES WILL BE MOSTLY CLEAR OVERNIGHT WITH LOW-LEVEL MOISTURE
BEGINNING TO ALLOW CLOUD COVERAGE BACK INTO THE AREA FROM THE
NORTHWEST DURING THE PRE-DAWN HOURS MONDAY. WITH INCREASED
CLEARING AND LIGHT WINDS OVERNIGHT...TEMPS HAVE BEEN LOWERED A FEW
DEGREES WITH INCREASED RADIATIONAL COOLING EXPECTED.

&&

.SHORT TERM /SUNDAY 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 SNOW
ACCUMULATION SUNDAY NIGHT INTO MONDAY. AT THIS POINT, EXPECT 1 TO
3 INCHES ACROSS MUCH OF THE FORECAST AREA WITH HIGHER AMOUNTS
NORTH AND OVER THE RIDGES.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
COLD NORTHWEST FLOW ACROSS THE LAKES WILL BRING LAKE EFFECT SNOW
SHOWERS FOR LATE MONDAY INTO TUESDAY. HIGH PRESSURE BUILDING INTO
THE DISTRICT TUESDAY NIGHT WILL BRING DRY WEATHER FOR TUESDAY
NIGHT AND WEDNESDAY. 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 AND SATURDAY.

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

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
THE DRY SLOT BEHIND THE COLD FRONT HAS BROUGHT CLEARING SKIES TO 
THE AIRPORTS FROM PIT AND WEST. THE CLEARING LINE WILL CONTINUE
EAST THIS EVENING WITH CONDITIONS AT DUJ LBE AND MGW IMPROVING TO
VFR. LARGE AREA OF LOW PRESSURE PUSHING INTO THE WESTERN GREAT LAKES
WILL BRING WRAP AROUND STRATOCU TO THE FORECAST AREA FROM WEST
TO EAST LATE TONIGHT INTO SUNDAY. IN THE COLD WRAP AROUND FLOW
FOR SUNDAY INTO TUESDAY EXPECT SCATTERED TO NUMEROUS SNOW SHOWERS
AND MVFR/IFR RESTRICTIONS IN SNOW SHOWERS. GENERAL MVFR STRATOCU CEILINGS
CAN BE EXPECTED OUTSIDE OF SHOWERS. HIGH PRESSURE WILL BUILD OVER
THE REGION TUESDAY NIGHT AND WEDNESDAY FOR DRY/VFR CONDITIONS. A
STORM MOVING TO THE ATLANTIC COAST THURSDAY WILL BRING A RISK OF
SNOW SHOWERS WITH GENERAL MVFR FLIGHT RESTRICTIONS.

&&

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

&&

$$