Area Forecast Discussion
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000 FXUS61 KPBZ 261927 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 327 PM EDT THU MAR 26 2015 .SYNOPSIS... MUCH COLDER AIR WILL SPILL IN TONIGHT AND LAST INTO THE WEEKEND...WITH SCATTERED RAIN AND SNOW SHOWERS LINGERING INTO FRIDAY NIGHT. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... FRONT HAS ADVANCED THROUGH LBE AND WILL PASS MGW SHORTLY. TIGHT TEMPERATURE GRADIENT EXISTS ACROSS THE BOUNDARY...WHICH IS HELPING TO FEED A STRONGER LINE OF SHRA ALONG THE FRONT IN THE RLX CWA. LIGHTER SHOWERS EXIST BEHIND. THUNDER HAS BEEN NONEXISTENT SO FAR...BUT COULD STILL SEE A LIGHTNING STRIKE OR TWO IN THE FAR SOUTHEAST OVER THE NEXT COUPLE OF HOURS. DESPITE THE QUICK COOLDOWN BEHIND THE FRONT...SUBZERO LOW LEVEL COLD AIR IS LAGGING THE BOUNDARY A BIT. THIS WILL DELAY THE CHANGEOVER TO SNOW FOR MOST AREAS UNTIL THE EVENING HOURS...ALTHOUGH THE FKL AREA SHOULD START TO SEE FLAKES BEFORE 00Z. WITH DEEP MOISTURE DEPARTING QUICKLY AND THE SNOW GROWTH ZONE ABOVE WHAT MOISTURE THERE IS...PLUS THE WARM GROUND... ACCUMULATIONS WILL HARD TO COME BY. EXPECTING LESS THAN AN INCH FOR THE MOST PART. SHOWER COVERAGE WILL BOTTOM OUT DURING THE PREDAWN HOURS...ALTHOUGH IT WILL START TO TICK UP AGAIN TOWARDS 12Z AS MAIN H500 SHORTWAVE STARTS TO APPROACH. OVERNIGHT TEMPERATURE FORECAST ALREADY IN GOOD AGREEMENT WITH GUIDANCE CONSENSUS AND MADE LITTLE CHANGE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... DEEP UPPER TROUGH WILL PIVOT ACROSS THE REGION WITH COLD ADVECTION AND NORTHWEST FLOW EXPECTED TO KEEP RAIN AND SNOW SHOWERS POSSIBLE THROUGH SATURDAY MORNING. WHILE DEEP MOISTURE WILL BE LIMITED...THERE IS A PERIOD FRIDAY NIGHT WHERE SEVERAL OF THE MODEL SOUNDINGS HAVE STEEP LAPSE RATES AND MOISTURE INTO THE DENDRITIC GROWTH ZONE AS THE BASE OF THE UPPER TROUGH CROSSES. THIS IS BETTER REPRESENTED IN THE FORECAST POINTS NORTH OF I-80 AND IN THE RIDGES WITH UPSLOPE SUPPORT...SO THE HIGHEST POPS WERE MAINTAINED IN THOSE LOCATIONS. WHILE SNOW MAY ACCUMULATE WITH FALLING TEMPERATURES AND STRONG COLD ADVECTION...IT SHOULD GENERALLY BE LESS THAN AN INCH AND MAINLY ON GRASSY SURFACES. 850HPA TEMPERATURES FALL TO NEAR -18C BY SATURDAY MORNING SO EXPECT BELOW AVERAGE TEMPERATURES FRIDAY NIGHT AND SATURDAY...WITH A GRADUAL WARMING TREND BY SUNDAY AS THE TROUGH SHIFTS TO THE EAST AND HIGH PRESSURE BUILDS OVERHEAD. HOWEVER WITH THE SURFACE RIDGE OVERHEAD SATURDAY NIGHT...CLEAR SKIES AND LIGHT WINDS MAY KEEP LOWS BELOW NORMAL. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... THE NEXT SYSTEM WILL QUICKLY MOVE THROUGH THE GREAT LAKES SUNDAY NIGHT...BRINGING THE RISK FOR RAIN OR SNOW AND ANOTHER SHOT OF COLD AIR ON MONDAY. DRY WEATHER AND A SLOW MODERATION IN TEMPS IS EXPECTED TUESDAY AND WEDNESDAY. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... IFR CONDITIONS WILL PERSIST FOR SEVERAL HOURS BEHIND THE BOUNDARY IN LINGERING LOW LEVEL MOISTURE. LITTLE CHANCE OF SEEING TSRA AT THE TERMINALS AT THIS POINT. SHOWER COVERAGE WILL DECREASE WITH TIME. CHANGEOVER TO SHSN WILL OCCUR SLOWLY TONIGHT...BUT CIG/VIS SHOULD MOSTLY BE MVFR AT WORST OVERNIGHT. EXPECTING SHOWER COVERAGE TO INCREASE AGAIN AFTER 12Z WITH APPROACH OF SHORTWAVE...BUT CIGS WILL KEEP SLOWLY IMPROVING THROUGH MVFR. GUSTY WINDS THIS AFTERNOON WILL DIMINISH BY EVENING AND SETTLE TOWARDS NW. .OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/... RESTRICTIONS ARE POSSIBLE INTO SATURDAY AS COLD ADVECTION CONTINUES IN THE WAKE OF THE FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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