Freeze Warning 1, NWS Pittsburgh, PA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
140 AM EDT SAT OCT 22 2011

.SYNOPSIS...
HIGH PRESSURE WILL BRING SLOW CLEARING THIS MORNING AND A WARM UP
TO NORMAL TEMPERATURES SUNDAY. A COLD FRONT, COMING EAST FROM THE
ROCKIES, WILL PROVIDE SCATTERED SHOWERS MONDAY.

&&

.NEAR TERM /THROUGH TODAY/...
PRECIPITATION HAS ENDED WITH BACK EDGE OF CLOUDS ONLY SLOWLY
EDGING EAST AS SURFACE RIDGE MOVES TOWARD THE UPPER OHIO VALLEY.

EXPECT LOWS TONIGHT, BASED ON BLEND OF RECENT GFS AND NAM MOS,
TO BE ONLY 2-4 DEGREES COLDER THAN NORMAL DUE TO REMAINING CLOUD
COVER, THAT IN PART SHOULD BE MAINTAINED BY 850 MB COLD POOL. IF
CLOUDS ARE ABLE TO BREAK BEFORE DAYBREAK MAY BE SOME FROST IN
EASTERN OHIO BUT FOR NOW NO MENTION. WITH RETURNING SUNSHINE TEMPERATURES
WILL WARM INTO THE 50S THIS AFTERNOON.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
WITH MOSTLY CLEAR SKIES TONIGHT TEMPERATURES WILL REACH THE 30S
MOST LOCATIONS WITH FROST POSSIBLE. ON SUNDAY, HIGH PRESSURE WILL
PROVIDE A DECENT AUTUMN DAY WITH SUNSHINE AND SEASONABLE
TEMPERATURES.

RECENT SREF MODEL OUTPUT CONTINUES TO SHOW A COLD FRONT, COMING
EAST FROM THE ROCKIES, WILL PROVIDE A CHANCE OF SHOWERS MONDAY.

PREFRONTAL CLOUDS AND MOISTURE SHOULD PROMOTE WARMER THAN NORMAL
LOWS SUNDAY NIGHT AND NEAR NORMAL VALUES MONDAY, AS INDICATED BY
GFS AND NAM MOS.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
BLEND OF RECENT NAEFS AND ECMWF MODEL OUTPUT SHOW A STRONGER COLD
FRONT, ALSO COMING EAST FROM THE ROCKIES, MOVING THROUGH THE UPPER
OHIO VALLEY WEDNESDAY. HAVE FORECASTED A CHANCE OF SHOWERS
STARTING LATE TUESDAY NIGHT. INFLUX OF COLDER AIR ON NORTHWEST
WINDS IN THE WAKE OF THE SYSTEM MAY MAINTAIN SHOWERS INTO FRIDAY.

FORECASTED TEMPERATURES, BASED ON RECENT GFS MOS AND NAEFS MEDIAN
VALUES, TO BE WARMER THAN NORMAL BY 5 TO 10 DEGREES INTO
WEDNESDAY. WITH THE POST SYSTEM CHILL DOWN, HIGHS THURSDAY AND
FRIDAY CAN BE 5 TO 10 DEGREES COLDER THAN NORMAL.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL MOSTLY PREVAIL ACROSS THE TERMINALS AS 3-4KFT
CEILINGS MOVE ACROSS THE REGION THIS MORNING. THE EXCEPTION WILL BE
AT KDUJ, WHERE IFR CONDITIONS WILL PREVAIL INTO THE MID-MORNING.
WITH SOME CLEARING POSSIBLE AT KZZV, A TEMPO GROUP HAS BEEN FORECAST
FOR MVFR VISIBILITIES NEAR DAWN THERE.

VFR CONDITIONS WILL MOSTLY PREVAIL ACROSS THE TERMINALS THIS
AFTERNOON AS HIGH PRESSURE CROSSES THE AREA. WINDS WILL BE LIGHT AND
SOUTHWESTERLY TODAY.

.OUTLOOK...SATURDAY NIGHT THROUGH WEDNESDAY...
VFR CONDITIONS WILL CONTINUE TO PREVAIL THROUGH SUNDAY NIGHT. A COLD
FRONT WILL RETURN THE CHANCE OF SHOWERS WITH RESTRICTIONS ON MONDAY.
A SECOND COLD FRONT WILL PROVIDE ANOTHER POTENTIAL ROUND OF SHOWERS
AND RESTRICTIONS STARTING LATE TUESDAY NIGHT INTO WEDNESDAY.

&&

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

&&

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