Area Forecast Discussion
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000 FXUS61 KPBZ 312339 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 639 PM EST SAT JAN 31 2015 .SYNOPSIS... LOW PRESSURE WILL BRING WINTRY WEATHER SUNDAY INTO MONDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... UPDT TO SKY COVER BASED ON SATELLITE AND NR TERM MDL DATA. WITH CLRG ERLY LOWERED TEMPS TO THE COLDER GFS NMBRS. PREVIOUS...HIGH PRES WL CONT TO BRING DRY WEA INTO THE EVE. A DIGGING UPR TROF AND DVLPG SFC LOW PRES WL BEGIN TO SPREAD SNW INTO THE RGN LT TNGT. MORE ON THIS IN THE SHORT TERM SECTION. ACCUMULATIONS BY MRNG SHOULD BE GENLY LESS THAN AN INCH AS THE PCPN WL JUST BE STARTING. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/... THAT DIGGING UPR TROF AND SFC LOW WL CONT TO ADVN OUT OF THE MIDWEST THRU OUR RGN SUNDAY MONDAY. MDLS HAVE SHIFTED THE TRACK OF THE SFC AND CLOSED 850 MB LOWS FURTHER N...SHIFTING THE FOCUS FOR HEAVIER SNW N OF PIT. A LLVL JET IS PROGGED TO DVLP ALG WITH DEEP MSTR AND INCRG OMEGA WITH WRM ADVCTN LTR SUN INTO SUN NGT...WHEN THE HEAVIEST PCPN IS EXPD. ALONG WITH THAT WRM ADVCTN...A CHANGEOVER TO MAINLY RAIN IS EXPD S OF I 70...WITH A MIX OF SNW...SLEET AND FRZG RAIN N TO ARND PIT. A BRF CHANGEOVER TO ALL RAIN IS PSBL AS WELL. N OF I 80 SHOULD STAY COLD ENOUGH FOR ALL SNW. GFS WAS FARTHEST N WITH THE SFC AND 850 MB LOWS...AND SEEMED TOO AGGRESSIVE WITH THE WRM ADVCTN. OPTED FOR THE COLDER NAM/ECMWF SOLNS WHICH ALLOWS FOR A LTL MORE GRADUAL OF A FCST SHIFT. RELIED ON CRITICAL THICKNESSES AND MDL SOUNDING PROFILES FOR PCPN TYPE FCST. ISSUED A WINTER STORM WARNING FOR AREAS N OF PIT WHERE 5 TO 10 INCHES OF SNW ARE EXPD. FM NR PIT AND S TO I 70 ISSUED WINTER WEA ADVYS FOR 2-5 INCHES OF SNW AND A POTENTIAL FOR A WINTRY MIX. WATCHES ARE NO LONGER IN EFFECT AS AREAS S OF THE PA BORDER...EVEN IN THE RIDGES...SHOULD CHG OVER TO MAINLY RAIN. FRZG PCPN IS PSBL ESP IN GARRETT COUNTY BUT HELD OFF ON ANY ADDNL HEADLINES ATTM. WRAP ARND SNW BEHIND THE EXITING LOW IS EXPD MON BUT ONLY ARND AN INCH OR TWO OF ADDNL SNW IS EXPD. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... ONLY CHANGE TO EXTENDED WAS TO SPEED UP FRONTAL PASSAGE WEDNESDAY AND BUMP UP POPS. NO OTHER CHANGES AS MUCH COLDER AIR POURS IN BEHIND THE FRONT AS A STOUT HIGH PRESSURE CENTERS OVERHEAD. TEMPERATURES EXPECTED TO BE WELL BELOW AVERAGE FROM MID-WEEK THROUGH THE END OF THE PERIOD. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS WILL PREVAIL THROUGH MOST OF THE NIGHT AS THE NEXT SYSTEM START TO INCREASE HIGH CLOUDS ACROSS THE AREA. SNOW WILL ADVANCE FROM SW TO NE ACROSS ALL SITES DURING THE OVERNIGHT AND PREDAWN HOURS. CONDITIONS WILL LIKELY RAPIDLY DETERIORATE TO IFR AT MOST SITES. THE TRACK OF THE SYSTEM IS CONTINUE TO MOVE FARTHER NORTHWEST ON THE LATEST FORECAST GUIDANCE SUCH THAT THE MID-LEVEL DRY SLOT IS LIKELY TO GO OVER ALMOST ALL SITES BY SATURDAY AFTERNOON OR EVENING. THIS SHOULD ALLOW FOR WARMER SURFACE AIR ALONG WITH DRIER AIR ALOFT TO MAKE SNOW TAPER TO LIGHT RAIN OR DRIZZLE. DEEPER MOSITURE WILL RETURN SUNDAY NIGHT...BRINGING RAIN SHWOERS THEN SNOW SHOWERS BACK INTO THE FORECAST ON MONDAY. FRIES .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... WIDESPREAD RESTRICTIONS CAN BE EXPECTED INTO MONDAY AS A LOW PRESSURE SYSTEM CROSSES THE REGION. NEXT CHANCE FOR WIDESPREAD RESTRICTIONS WILL BE WITH A WEDNESDAY COLD FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...WINTER WEATHER ADVISORY FROM 4 AM SUNDAY TO NOON EST MONDAY FOR OHZ039-040-048>050-057>059. WINTER STORM WARNING FROM 4 AM SUNDAY TO NOON EST MONDAY FOR OHZ041. PA...WINTER WEATHER ADVISORY FROM 4 AM SUNDAY TO NOON EST MONDAY FOR PAZ021-029-073-074. WINTER STORM WARNING FROM 4 AM SUNDAY TO NOON EST MONDAY FOR PAZ007>009-013>016-020-022-023. WV...WINTER WEATHER ADVISORY FROM 4 AM SUNDAY TO NOON EST MONDAY FOR WVZ001>003. && $$

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