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000
FXUS61 KPBZ 260113 AAB
AFDPBZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
913 PM EDT SAT MAY 25 2013

.SYNOPSIS...
DRY AND COLD WEATHER CAN BE EXPECTED FOR THE WEEKEND. WARM AND
HUMID CONDITIONS WILL RETURN BY MID-WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
CIRRUS CONTINUES TO SPREAD EASTWARD...SO AGAIN...NEEDED TO MAKE
ADJUSTMENTS TO CLOUD COVER OVERNIGHT. AS THINGS STAND...CONFIDENCE
WANING IN THE HEADLINES FOR TONIGHT. WARMER TEMPS TODAY AND
INCREASED CLOUD COVER...WILL MAKE IT DIFFICULT TO REACH COLD
TEMPS. HOWEVER...LATEST HIRES MODELS ARE INDICATING THAT MUCH OF
THE CIRRUS WILL DISSIPATE BEFORE DAWN ALLOWING FOR A COUPLE OF
GOOD HOURS OF RADIATIONAL COOLING.

PREVIOUS FORECAST...

SURFACE HIGH WILL CONTINUE TO BUILD OVER THE REGION AS THE UPPER
LOW ROTATES OVER NEW ENGLAND. TIGHTENED PRESSURE GRADIENT FLOW
BETWEEN THE TWO SYSTEMS WILL ALLOW FOR SOME STRONGER NORTHWESTERLY
WINDS TO CONTINUE...ALTHOUGH FOCUSED A BIT FURTHER EAST THAN
YESTERDAY. BEYOND SOME SCATTERED DIURNAL CU...SOME HIGH CIRRUS
FROM A CONVECTIVE SYSTEM OFF TO THE WEST MAY MAKE IT INTO THE
WESTERN ZONES. HOWEVER...MOST OF THE FORECAST AREAS SHOULD SEE A
MOSTLY SUNNY DAY. DESPITE THE SUNSHINE...COLD NORTHWEST FLOW WILL
KEEP TEMPERATURES 10 TO 15 DEGREES BELOW SEASONAL NORMALS ONCE
AGAIN TODAY.

WITH BUILDING HIGH CONTINUING ITS PROGRESSION EASTWARD...EXPECT
ANOTHER CALM...CLEAR NIGHT TONIGHT. HOWEVER...WITH THE BOUNDARY
LAYER WARMING SLIGHTLY...FOCUS OF WIDESPREAD FROST/FREEZE HAS
SHIFTED A BIT FARTHER NORTH AND EAST. DID HOWEVER EXPAND FREEZE
AND FROST PRODUCTS PER COORDINATION WITH ADJACENT OFFICES AND
RELATIVELY LOW DEWPOINTS REMAINING OVER THE REGION. WHILE
CONFIDENCE IN A WIDESPREAD FREEZE IN THE HIGHER ELEVATIONS REMAINS
LOW...ISOLATED POCKETS OF BELOW-FREEZING TEMPERATURES COULD
OCCUR...ESPECIALLY IN THE MORE SHELTERED VALLEYS.

SUNDAY SHOULD ONCE AGAIN BE A QUIET WEATHER DAY WITH TEMPERATURES
MODERATING A FEW DEGREES CLOSER TO NORMAL. WIND GUSTS SHOULD
CONTINUE TO DIMINISH AS HIGH SETTLES OVERHEAD.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
AS CLOSED LOW OVER NEW ENGLAND OPENS AND EXITS NEWD...FCST AREA
WILL RMN UNDER INFLUENCE OF RDG. LGT WINDS AND CLR SKIES XPCD SUN
NGT AND MON FOR MUCH OF RGN. AS A RESULT...TEMPS ONCE AGAIN XPCD
TO DROP LATE SUN NGT. FRZ WATCH WAS ISSUED FOR NRN ZONES...WHERE
TEMPS FCSTD TO BE VERY NR OR BLW FRZG. WITH UPR RDG RMNG TO W OF
FCST AREA THRU MON NGT...VERY LOW POPS WERE CONTD THRU THE PD.

WMFNT APRCHS ON TUE AS UPR RDG SHIFTS EWD. MSTR WILL BE SLOW TO
RETURN TO THE AREA...SO ONLY LOW POPS WERE MAINTAINED THRU TUE
NGT. ANY PCPN WILL BE TIED TO TIMING OF LOW-AMPLITUDE SHRTWV TROFS
THAT ARE POORLY RESOLVED ATTM...BUT CANNOT RULE OUT PSBLTY OF A
TSTM GIVEN XPCD WARM AIR ADVCTN.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
UPR RDG WILL AMPLIFY OVER ERN CONUS RMNDR OF THE WK AS SWLY LOW-
LVL FLOW INCRS. THIS FLOW WILL PROVIDE AMPLE MSTR AND HEAT TO THE
RGN. TEMPS IN MID-UPR 80S XPCD TO RETURN BY MID-WK.

ALTHOUGH LOW-LVL MSTR WILL BE PRESENT...LACK OF A BNDRY AND
UNCERTAIN SPHERE OF INFLUENCE OF STG UPR RDG WILL LMT PCPN CVRG.
GIVEN LOW CONFIDENCE IN AMPLITUDE AND NWD POSITION OF UPR RDG...
POPS CANNOT BE RULED OUT COMPLETELY. WITH MODEST INSTBY PRESENT...
SLGT CHC TSTMS WILL BE CARRIED DAILY THRU THE EXTENDED PDS UNTIL
IT IS CLEAR WHETHER CAPPING/SUBSIDENCE OR HEATING WILL WIN OUT.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS SHOULD CONTINUE OVERNIGHT AS HIGH PRESSURE BUILDS
EASTWARD. GUSTY NORTHWEST WINDS WILL QUICKLY DIMINISH AFTER
SUNSET. SOME PATCHY RIVER VALLEY FOG TOWARD DAYBREAK. FOR
NOW...LEFT OUT THIS MENTION IN THE TAFS AS IT MAY HAVE LITTLE
IMPACT ON TERMINALS.

.OUTLOOK.../SATURDAY NIGHT THROUGH WEDNESDAY/...
VFR CONDITIONS WILL CONTINUE THROUGH MONDAY. SOME RESTRICTIONS IN
SCATTERED SHOWERS AND THUNDERSTORMS RETURN TUESDAY AND WEDNESDAY AS
A WARM FRONT MOVES SLOWLY NORTH ACROSS THE OHIO VALLEY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...FROST ADVISORY FROM 2 AM TO 8 AM EDT SUNDAY FOR MDZ001.
OH...FROST ADVISORY FROM 2 AM TO 8 AM EDT SUNDAY FOR OHZ040-041-050.
PA...FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR
     PAZ007>009-015-016.
     FREEZE WARNING FROM 2 AM TO 8 AM EDT SUNDAY FOR PAZ007>009-015-
     016.
     FROST ADVISORY FROM 2 AM TO 8 AM EDT SUNDAY FOR PAZ013-014-
     020>023-029-031-073>076.
WV...FROST ADVISORY FROM 2 AM TO 8 AM EDT SUNDAY FOR WVZ001>004-012-
     021>023-041.

&&

$$
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