Area Forecast Discussion
Issued by NWS

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000 FXUS61 KPBZ 020042 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 742 PM EST SUN FEB 1 2015 .SYNOPSIS... LOW PRESSURE WILL APPROACH AND CROSS THE REGION THROUGH MONDAY. MUCH COLDER AIR IS EXPECTED EARLY IN THE WEEK. && .NEAR TERM /THROUGH MONDAY/...
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WITH 730PM UPDATE...HAVE ADDED FREEZING RAIN FOR THE NEXT COUPLE OF HOURS AROUND THE PITTSBURGH METRO AREA. REPORTS OF FREEZING RAIN HAVE COME IN FROM BEAVER AND BUTLER COUNTIES...AND FREEZING RAIN IS ALSO BEING OBSERVED AT THE NWS OFFICE. ALTHOUGH AIR TEMPERATURES ARE READING 32 TO 34 AROUND THESE LOCATIONS...THIS APPEARS TO BE ANOTHER CASE WHERE AIR TEMPERATURES ARE WARMING UP MORE QUICKLY THAN SURFACE TEMPERATURES. SO FAR ALL REPORTS HAVE BEEN REPORTED INSIDE OF THE WINTER WEATHER ADVISORY AREA...SO NO CHANGED TO HEADLINES ARE NEEDED AT THIS TIME. WILL CONTINUE TO MONITOR EVOLUTION OF FREEZING RAIN. WITH 6PM UPDATE...PRIMARY CHANGES WERE TO UPDATE HOURLY TEMPERATURES AND SUBSEQUENT WEATHER TYPES ACROSS THE CENTRAL TIER OF THE FORECAST AREA. NUDGED RAIN-SNOW LINE SLIGHTLY FARTHER NORTH DURING THE EVENING HOURS...WHICH SHOULD ALLOW FOR MORE OF A MIX OF RAIN AND SNOW ALONG THE PENNSYLVANIA TURNPIKE CORRIDOR. PARTIAL THICKNESSES AND MODEL SOUNDINGS INDICATE THAT WHILE RAIN COULD MAKE ITS WAY AS FAR NORTH AS INTERSTATE 80...STILL THINK LOCATIONS NORTH OF THE INTERSTATE WILL REMAIN SNOW THE ENTIRE TIME. PREVIOUS DISCUSSION FOLLOWS. SFC LOW PRES WAS CENTERED OVER IL WL CONT TO ADVN ACRS THE RGN TNGT TRACKING OVR WRN PA. THE 850 MB LOW IS PROGGED TO TRACK ACRS NW PA AND LAKE ERIE...KEEPING THE HEAVIEST SNW AXIS ACRS NWRN PA. ANOTHER AREA OF DEEP MSTR AND OMEGA IS EXPD TO MOVE ACRS THE AREA AGAIN THIS EVE. CRITICAL THICKNESSES AND MDL SOUNDING PROFILES SHOW WRM ADVCTN ACRS THE RGN THRU TNGT. THIS SHOULD ALLOW SNW TO MIX WITH OR CHG TO RAIN WITH A PSBL BRIEF PD OF FRZG RAIN S OF I 80...REDUCING SNW TOTALS TNGT. FOR THIS REASON CHGD THE WINTER STORM WRNG TO AN ADVY S OF I 80...BUT KEPT THE WRNG N AS PCPN SHOULD STAY ALL SNW THERE. CANCELLED ADVYS IN OTHER AREAS WHERE PCPN HAS TAPERED OFF AND WHERE NO SIGNIFICANT SNW/ICE ACCUMULATIONS ARE EXPD. CONTD THE ADVY FOR ALLEGHENY COUNTY AND SURROUNDING AREAS BUT THIS PORTION COULD BE CANCELLED ERLY IF TEMPS WRM SUFFICIENTLY. GENLY FOLLOWED THE DETAILS OF THE NAM WHICH WAS SLGTLY LESS AGGRESSIVE THAN THE GFS WITH WRM ADVCTN TNGT. ADDNL SNW SHWRS ARE EXPD MON AS THE UPR TROF AXIS CROSSES AND STRONG COLD ADVCTN SETS UP. UPSLOPE FLOW SHOULD SET UP AS WELL...BUT MSTR THINS QUICKLY IN THE SNW GROWTH RGN WHICH SHOULD HELP LIMIT ACCUMULATIONS TO ARND A COUPLE OF INCHES IN THE RIDGES. USED A NAM/GFS BLEND FOR TEMPS.
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&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... COLD HIGH PRESSURE WILL BRING AN END TO LINGERING SNOW SHOWERS WITH CLOUDS BREAKING SOMEWHAT MONDAY NIGHT. LOWS WILL BE IN THE SINGLE DIGITS WITH BELOW ZERO ACROSS THE NORTH. QUIET AND COLD TUESDAY. NEXT COLD FRONT AND ASSOCIATED SHORTWAVE WILL APPROACH LATER TUESDAY NIGHT AND WEDNESDAY WITH INCREASING CHANCES FOR SNOW SHOWERS. TEMPERATURES AHEAD OF THE FRONT WEDNESDAY WILL MODERATE TO NEAR THE SEASONAL AVERAGES. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... COLD AND DRY HIGH PRESSURE WILL DOMINATE INTO SATURDAY. LOW PRESSURE WILL BRING THE CHANCE FOR SNOW SHOWERS LATER SATURDAY NIGHT INTO SUNDAY. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... CENTRAL AND SOUTHERN AIRPORTS HAVE IMPROVED TO MVFR. IFR TO LIFR CIGS AND SNOW WILL REMAIN FOR KFKL AND KDUJ THROUGH THE PERIOD...AND AS SURFACE LOW MOVES EAST ACROSS THE UPPER OHIO VALLEY OVERNIGHT IFR CIGS AND VSBY IN RAIN WILL REDEVELOP. COLD AIR WRAPS IN QUICKLY BEHIND SYSTEM MONDAY MORNING WITH A PERIOD OF IFR SNOW SHOWERS AS WINDS SHIFT TO THE WEST AND NORTHWEST WITH GUSTS TO 30 KTS. OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/... NEXT CHANCE FOR WIDESPREAD RESTRICTIONS WILL BE WITH A WEDNESDAY COLD FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...WINTER WEATHER ADVISORY UNTIL NOON EST MONDAY FOR OHZ040-041. PA...WINTER STORM WARNING UNTIL NOON EST MONDAY FOR PAZ007>009-015- 016. WINTER WEATHER ADVISORY UNTIL NOON EST MONDAY FOR PAZ013-014- 020>023-073-074. WV...NONE. && $$

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