FXUS61 KPBZ 261955
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
255 PM EST SAT DEC 26 2009
.SYNOPSIS...
HIGH PRESSURE WILL PASS SOUTH OF THE AREA TONIGHT WITH DRY WEATHER
CONTINUING INTO EARLY ON SUNDAY. AN UPPER LEVEL LEVEL LOW WILL
CROSS THE GREAT LAKES SUNDAY...BRINGING A DISTURBANCE WITH LIGHT
SNOW ACROSS THE AREA SUNDAY NIGHT AND MONDAY. HIGH PRESSURE WILL
BUILD IN FROM THE WEST BY MID-WEEK...DRYING CONDITIONS ACROSS THE
AREA.
&&
.NEAR TERM /THROUGH TONIGHT/...
19Z 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 1003 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. A DEEPER LAYER OF DRY AIR CONTINUES TO BUILD IN
FROM THE SOUTHWEST...WITH CLEARING SKIES FROM THE WEST.
TONIGHT...DRY AIR ADVECTING INTO THE REGION WILL CONTINUE TO
DEEPEN AS HIGH PRESSURE PASSES SOUTH OF THE AREA. CLOUD COVERAGE
WILL FINALLY BEGIN TO DIMINISH ACROSS THE EASTERN RIDGES WITH MOSTLY
CLEAR SKIES OTHERWISE THIS EVENING WITH THE AREA IN A DRY SLOT. LOW-
LEVEL MOISTURE WILL ALLOW CLOUD COVERAGE TO ADVECT 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 SOME RADIATIONAL COOLING EXPECTED.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
THE UPPER LEVEL LOW WILL MOVE ACROSS THE LOWER GREAT LAKES WITH
ITS ASSOCIATED TROUGH AXIS ADVECTING ACROSS THE OHIO VALLEY ON
SUNDAY. A SURFACE TROUGH WILL BE THE FOCAL POINT OF SNOW SHOWERS
ADVECTING INTO EAST CENTRAL OHIO BY SUNDAY AFTERNOON. CLOUD
COVERAGE WILL INCREASE FROM THE NORTHWEST THROUGHOUT THE
DAY...LIMITING TEMPS SOMEWHAT. FORECAST CONSISTS PRIMARILY OF A
NAM/GFS BLEND...WITH NEAR NORMAL VALUES FOR HIGHS SUNDAY.
SUNDAY NIGHT AND MONDAY...THE UPPER LEVEL CLOSED LOW AND TROUGH
AXIS WILL CONTINUE TO TRANSLATE EASTWARD ACROSS THE LOWER GREAT
LAKES WITH THE AXIS OF THE TROUGH EXTENDING ACROSS WESTERN PA BY 12Z
MONDAY. GFS/NAM ARE IN REASONABLE AGREEMENT WITH THIS FEATURE
BRINGING AN ACCUMULATING SNOWFALL TO THE REGION STARTING SUNDAY
NIGHT. H5 VORT ENERGY WITH THIS SYSTEM APPEARS TO BE SUPPORTIVE
FOR THE BEST CHANCE OF A LIGHT SNOW AROUND DAWN ON MONDAY. THIS IS
HIGHLIGHTED IN THE HWO...WITH POTENTIAL IMPACTS TO THE MORNING
COMMUTE. 1 TO 3 INCHES ARE EXPECTED DURING THIS PERIOD...WITH THE
HIGHEST ACCUMULATIONS ALONG THE EASTERN RIDGES. AS THE TROUGH AXIS
MOVES EAST OF THE AREA...FLOW ALOFT WILL BECOME
NORTHWESTERLY...ALLOWING FOR UPSLOPING AND LAKE ENHANCEMENTS
MONDAY AFTERNOON INTO EARLY ON TUESDAY. TOTAL ACCUMULATIONS OF 3
TO 6 WILL BE POSSIBLE ACROSS THE LAKE EFFECT ZONES AND THE
EASTERN RIDGES THROUGH MONDAY NIGHT. COLD AIR ADVECTION THROUGHOUT
THE DAY WILL ONLY ALLOW TEMPS TO WARM INTO THE UPPER 20S MONDAY
WITH LOWS IN THE MID TO UPPER TEENS MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
COLD NORTHWEST FLOW ACROSS THE LAKES WILL BRING LAKE EFFECT SNOW
SHOWERS 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 /19Z 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.
&&
$$
