Area Forecast Discussion
Issued by NWS

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000 FXUS61 KPBZ 271747 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 1247 PM EST TUE JAN 27 2015 .SYNOPSIS... LIGHT SNOW AND FLURRIES WILL PERSIST TODAY BEFORE HIGH PRESSURE BUILDS AND DECREASES CLOUDS TONIGHT. A COLD WEDNESDAY MORNING WILL FOLLOW. && .NEAR TERM /THROUGH TONIGHT/...
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ONLY MINOR TWEAKS TO HOURLY TRENDS WERE NEEDED FOR THE EARLY AFTN UPDATE AS LGT DEFORMATION ZONE SNOW CONTS...ALBEIT WEAKLY. THAT ZONE WL SHIFT EWD AND CONT TO WEAKEN AS NEW ENGLAND LOW LIFTS NEWD. OTHERWISE...DRY SFC HIGH PRES WL BLD EWD UNDR NNWLY FLOW ALOFT TNGT. A CLEARING SKY...LGT WIND...AND WIDESPREAD SNOW COVER WL SPPRT A TEMP SIGNIFICANT TEMP DROP WITH SINGLE DIGITS ANTICIPATED FOR THE ENTIRE AREA...WITH READINGS ARND...OR A FEW DEGREES BELOW ZERO ANTICIPATED FOR COUNTIES NORTH OF PITTSBURGH. THESE ADJUSTMENTS WERE COMPLETED WITH A BLEND OF GUIDANCE TRENDS AND PERSISTENCE.
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&& .SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
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WEDNESDAY HIGHS WERE LIMITED TO ROUGHLY 10 DEGREES UNDR THE AVGS WITH SFC HIGH PRES SLIDING ACRS THE UPR OH REGION. SHRTWV RIDGING WL MAINTAIN DRY CONDITIONS THROUGH WEDNESDAY NIGHT...BUT STRENGTHENING WARM ADVCTN IN ADVN OF TROUGH DIGGING RAPIDLY TWD THE WRN LAKES WL IMPROVE THE THURSDAY MRNG LOWS. THE NAM...GFS...ECMWF FORECASTED CENTER TRACK OF THAT SYSTEM RMNS N OF THE REGION...HENCE CONTD WARM ADVCTN ON THE ERN FLANK IS EXPECTED TO LIMIT SNOW ACCUMULATION POTENTIAL. HOWEVER...THE SCENARIO WL FAVOR A WINTRY MIX COMPLICATED BY COLD SURFACES LEFTOVER OVR FM THE PREVIOUS TWO NGTS. ANY PCPN THAT DOES TURN TO RAIN WL STILL HAVE THE POTENTIAL TO FREEZE ON CONTACT. IN ADDITION...THE DRY LAYER WHICH IS PROGGED TO LIMIT PCPN ONSET IN THE MRNG MAY OFFSET A WEAKER WARM ADVCTN REGIME VIA WET BULBING. BOTTOM LINE IS THAT FORECAST WL FEATURE A WINTRY MIX WITH A CHANGE TO SNOW WITH PASSAGE OF THE SYSTEMS COLD FRONT ON THURSDAY EVENING. A HAZARDOUS WEATHER OUTLOOK WAS ALSO INCLUDED FOR THE FREEZING RAIN POTENTIAL. QPF WAS COMPLETED USING HPC GUIDANCE TRIMMED FOR LOCAL POP TRENDS WITH SNOW TOTALS ADJUSTED FOR SFC TEMP EXPECTATIONS. IN THE WAKE OF THE FRONT...COLD TEMPS WL AGAIN VISIT THE REGION. DEPTH OF COLD AT MOMENT LKS SUFFICIENT TO SPPRT SNOW SHWRS...SO LIKELY POPS WERE MAINTAINED OVR THE RIDGES PAST DAYBREAK DESPITE DRY ADVCTN AND LACK OF ANY REINFORCING LAKE ERIE MSTR DUE TO ICE.
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&& .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... COLD ARCTIC HIGH SHIFTS EAST INTO SATURDAY WITH SNOW SHOWERS IN NORTHWEST FLOW FRIDAY ENDING FRIDAY NIGHT. WITH 850MB TEMPS PROGGED NEAR -20C BY 00Z SATURDAY TEMPERATURES FRIDAY WILL BE STEADY OR FALL. CLOUDS SHOULD BEGIN TO BREAK AS CENTER OF HIGH MOVES INTO REGION FRIDAY NIGHT...WITH LOWS BELOW ZERO NORTH AND SINGLE DIGITS SOUTH. IF CONDITIONS GO CLEAR AND CALM FRIDAY NIGHT MAY GO BELOW ZERO ACROSS THE ENTIRE REGION. TEMPERATURES RECOVER TO MAINLY THE 20S SATURDAY. A SIGNIFICANT STORM LOOKS POSSIBLE FOR SUNDAY INTO EARLY MONDAY BEFORE ARCTIC AIR RETURNS TO START THE WORK WEEK. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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MVFR CIGS WILL CONTINUE THROUGH THE AFTERNOON INTO THE EVENING HOURS. MVFR/VFR VISIBILITY SNOW WILL ALSO CONTINUE...WITH AN OCCASIONAL IFR VISIBILITY POSSIBLE. SNOW SHOULD COME TO AN END DURING THE EVENING HOURS. CEILINGS SHOULD BEGIN TO SLOWLY LIFT AS CLOUDS SCATTER OUT DURING THE LATE EVENING INTO EARLY MORNING HOURS. CLEAR SKIES ARE EXPECTED BY SUNRISE. A GUST TO 15-20 KTS IS POSSIBLE THROUGH MIDNIGHT WITH WINDS VEERING FROM NORTHWEST TO WEST...AND WINDS SHOULD DROP UNDER 5 KT FOR WEDNESDAY. .OUTLOOK.../WEDNESDAY THROUGH SUNDAY/... WIDESPREAD RESTRICTIONS ARE EXPECTED ON THURSDAY WITH CROSSING LOW PRESSURE. FREEZING PRECIPITATION IS POSSIBLE AT ALL TERMINALS THURSDAY WITH PRECIPITATION CHANGING OVER TO SNOW BY MIDNIGHT FRIDAY. RESTRICTIONS WILL CONTINUE INTO FRIDAY. VFR CONDITIONS ARE EXPECTED SATURDAY...WITH ANOTHER SET OF RESTRICTIONS POSSIBLE SUNDAY.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ 15/33

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