FXUS61 KPBZ 010133
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
833 PM EST MON NOV 30 2009
.SYNOPSIS...
COLD NORTHWEST WINDS WILL BRING SOME SNOW SHOWERS TO THE UPPER
OHIO VALLEY OVERNIGHT INTO TUESDAY MORNING. HIGH PRESSURE WILL
THEN BRING DRY CONDITIONS LATER TUESDAY AND TUESDAY NIGHT. A
DEEPENING LOW PRESSURE SYSTEM MOVING NORTH FROM THE GULF STATES
WILL BRING RAIN WEDNESDAY AND WEDNESDAY NIGHT FOLLOWED BY SNOW
SHOWERS LATER THURSDAY.
&&
.NEAR TERM /THROUGH TUESDAY/...
JUDGING FROM RECENT SURFACE AND RADAR DATA COUPLED WITH SREF MODEL
OUTPUT AND NAM MODEL PROFILES...CONTINUE TO EXPECT THE BULK OF LAKE
EFFECT SNOW SHOWERS OVERNIGHT INTO TUESDAY MORNING TO AFFECT THE
I-80 CORRIDOR AND APPALACHIAN MOUNTAINS. WITH SURFACE LAYER WINDS
TURNING WESTERLY OVERNIGHT...MOST SNOW ACCUMULATIONS SHOULD BE MAINLY LESS
THAN AN INCH. THE REST OF THE UPPER OHIO VALLEY WILL MAINLY GET
ISOLATED SNOW SHOWERS WITH LITTLE IF ANY ACCUMULATION.
RECENT SREF MODEL OUTPUT CONTINUES TO SHOW AN UPPER TROUGH MOVING
THROUGH WESTERN NEW YORK STATE TUESDAY MORNING THAT CAN BRUSH
NORTHERN VENANGO AND FOREST COUNTIES WITH A SMALL SNOW
ACCUMULATION THEN. ELSEWHERE...NAM MODEL PROFILES SHOW THE SURFACE LAYER
STABILIZING AND VERTICALLY SHRINKING AND WINDS TURNING
WESTERLY...SO SNOW SHOWERS WILL BE ENDING BY AFTERNOON.
SURFACE WINDS CAN GUST TO 20-25 MPH.
FORECASTED TEMPERATURES USING A BLEND OF RECENT RUC AND SREF MODEL
OUTPUT COUPLED WITH GFS MOS. ALTHOUGH CONDITIONS FEEL
COLD...ACTUAL TEMPERATURES THIS PERIOD WILL BE ACTUALLY CLOSE TO
NORMAL.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
MODELS HAVE COME INTO BETTER AGREEMENT OVERALL WITH SOUTHERN
STREAM CLOSED LOW OPENING AND QUICKLY MOVING NORTHEAST WEDNESDAY
AND WEDNESDAY NIGHT WITH SURFACE LOW MOVING QUICKLY TO OHIO VALLEY
BY THURSDAY MORNING AND THEN TO NEW YORK STATE BY LATE DAY. RAIN
WILL OVERSPREAD THE REGION WEDNESDAY AND CONTINUE INTO WEDNESDAY
NIGHT. DRY SLOT WILL THEN WORK INTO REGION THURSDAY MORNING AS
SURFACE LOW HEADS NORTH AND COLDER AIR WRAPS IN BEHIND SYSTEM
CHANGING PRECIP TO SNOW SHOWERS BY EVENING. MILD AHEAD OF
WEDNESDAY THEN COOLER THURSDAY BEHIND FROPA.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
DEEP DIGGING CLOSED LOW WILL MOVE FROM NORTHERN PLAINS TO GREAT
LAKES THROUGH PERIOD BRINGING COLDEST AIR OF SEASON WITH OFF AND
ON SNOW SHOWERS DUE TO LAKE EFFECT AND DISTURBANCES MOVING UNDER
CLOSED LOW. NOT MUCH TO ARGUE WITH FROM HPC PROGS AND FOLLOWED.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
BASED ON RECENT SURFACE AND RADAR DATA...EXPECT SCATTERED BANDS OF
SNOW SHOWERS TO CAUSE BRIEF IFR CONDITIONS OVERNIGHT INTO TUESDAY
MORNING TO LOCATIONS WITHIN THE I-80 CORRIDOR AND NEAR THE
APPALACHIAN MOUNTAINS. ELSEWHERE ACROSS THE UPPER OHIO VALLEY
CONTINUE TO EXPECT MAINLY VFR THAT CAN BE BRIEFLY PUNCTUATED BY
MVFR.
SURFACE WINDS WILL GO WESTERLY 10-15 KTS OVERNIGHT TO
SOUTHWESTERLY 10 TO 20 KTS DAYTIME TUESDAY.
HIGH PRESSURE WILL PROVIDE PREVALENT VFR CONDITIONS LATE TUESDAY INTO
WEDNESDAY. A STRONG STORM SYSTEM MOVING NORTHEAST FROM THE DEEP
SOUTH WILL BRING RESTRICTIONS IN RAIN THURSDAY...AND SNOW SHOWERS
FRIDAY AND SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
