Area Forecast Discussion
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000 FXUS61 KPBZ 250616 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 116 AM EST WED FEB 25 2015 .SYNOPSIS... A COLD FRONT WILL MOVE THROUGH TONIGHT WITH LIGHT SNOW SHOWERS. BELOW AVERAGE TEMPERATURES WILL REMAIN THROUGH THE WEEK. && .NEAR TERM /THROUGH TODAY/...
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APPROACHING FRONT NOW JUST NORTH AND WEST OF OHIO WITH WITH LATEST GUIDANCE INDICATING PLACEMENT OVER EASTERN OHIO ZONES SHORTLY BEFORE DAYBREAK AND EAST OF THE RIDGES BY LATE MORNING. GIVEN THE LATER TIMING...HAVE INCREASED NEAR TERM TEMPERATURES...MOST SIGNIFICANTLY ACROSS THE NE OHIO AND NW PA AS THERE WILL BE SUFFICIENT SOUTHWESTERLY WINDS AHEAD OF THEW FRONT TO KEEP LOWER LEVELS WELL MIXED THROUGH THE MAJORITY OF THE NIGHT. DO NOT ANTICIPATE MUCH RECOVERY DURING THE DAY WITH WINDS SHIFTING NORTHWEST FOLLOWING THE MORNING FRONTAL PASSAGE. PREV DISCUSSION FOLLOWS.. A VERY DRY BOUNDARY LAYER REMAINS OVER THE REGION THIS EVENING AFTER THE WARM DAY...SOME MOISTURE INPUT FROM MELTING...SOUTHWESTERLY BOUNDARY LAYER FLOW...AND MID-LEVEL RH MOISTURE INCREASING ENOUGH TO BRING SOME CLOUDS OVER THE AREA. ALL OF THESE THINGS HAVE DONE LITTLE TO ALTER THE LOW LEVEL MOISTURE PROFILE...EVEN WHILE TEMPERATURES ARE SITTING 25 DEGREES OR SO WARMER THAN YESTERDAY. THIS WILL POSE A PROBLEM AS THE NEXT SYSTEM SLIPS TOWARD OUR AREA OVERNIGHT. AS MENTIONED...MID LEVEL RH VALUES ARE ALREADY UP...AND A FAIRLY SHARP SHORT WAVE TROUGH AND ASSOCIATED BALLED UP VORT MAXIMA LOOK TO MOVE ACROSS LAKE ERIE LATE THIS EVENING. DIFFERENTIAL PVA AND A STEEPENING OF THE LOW LEVEL LAPSE RATES DUE TO COLD ADVECTION OFF THE DECK SHOULD ALLOW FOR SUFFICIENT LIFT TO BE GENERATED TO DEVELOP SOME SNOW SHOWERS ACROSS THE NORTHERN TIER THAT WILL BE STRONG ENOUGH TO MOISTEN UP THE BOUNDARY LAYER. THE FARTHER YOU GO SOUTHWARD...THE MORE PROBLEMATIC THE EQUATION BECOMES TO GENERATING SNOW SHOWERS. WITH LIFT BEING MORE DISTANT...AND LOW LEVEL LAPSE RATES LESS UNSTABLE...NOT TO MENTION LESS INSTABILITY BISECTING THE LOWER REACHES OF THE DENDRITIC GROWTH ZONE...SNOW SHOWERS WILL BE FAR LESS COMMON SOUTH OF I-80 AND ESPECIALLY SOUTH OF THE TURNPIKE. IN REALITY...ACCUMULATING SNOW ONLY REALLY SEEMS POSSIBLY ACROSS THE FAR NORTH. ADDITIONALLY...AS STEEPER LAPSE RATES REACH THE RIDGES...A FEW UPSLOPE SNOW SHOWERS WITH MINIMAL ACCUMULATIONS AGAIN SEEM LIKELY THERE BY MORNING. DUE TO ABUNDANT CLOUDS AND WARM ADVECTION THIS EVENING...LOWS WILL BE LEAPS AND BOUNDS WARMER THAN LAST NIGHT. HOWEVER...THESE WILL LIKELY REMAIN WELL BELOW NORMAL. DRIER AIR SHOULD AGAIN RETURN FOR THE DAYTIME ON WEDNESDAY...WHICH SHOULD ALLOW FOR SOME EROSION OF THE CLOUDS. HOWEVER...THIS CLEARING WILL LIKELY BE SHORT LIVED...AS THE NEXT COUPLET OF SYSTEMS HEADS TOWARD THE REGION BY WEDNESDAY NIGHT AND THURSDAY. FRIES
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&& .SHORT TERM /TONIGHT THROUGH FRIDAY/... COMBINATION OF SYSTEMS FOR WEDNESDAY NIGHT AND THURSDAY WITH A NORTHERN STREAM SHORTWAVE AHEAD OF ANOTHER COLD CANADIAN SURFACE HIGH MOVES SOUTH...WHILE A SUPPRESSED SOUTHERN STREAM WAVE SHEARS OUT ACROSS THE MID ATLANTIC STATES. DEEP MOISTURE WILL BE LACKING BUT DO EXPECT SNOW SHOWERS AT TIMES BEFORE DAYBREAK THURSDAY MORNING CONTINUING THURSDAY. COLD FRONT WILL EXIT AS SURFACE HIGH BUILDS SOUTHEAST THURSDAY NIGHT INTO FRIDAY. CONTINUED QUITE COLD THROUGH THE PERIOD WITH LOWS NEAR OR BELOW ZERO AGAIN FOR THURSDAY NIGHT. TEMPERATURES WILL HOLD MAINLY IN THE TEENS FRIDAY. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ONLY SIGNIFICANT CHANGES WERE TO TEMPERATURES EARLY IN THE EXTENDED PERIOD. ARCTIC HIGH WITH CLEARING SKIES SHOULD ALLOW FOR SIGNIFICANT RADIATIONAL COOLING FRIDAY NIGHT AND TOOK TEMPERATURES DOWN TOWARD NEWEST WPC GUIDANCE FRIDAY NIGHT. LOWERED MAX TEMPS FOR SATURDAY AS WELL. PATTERN MUDDIES THEREAFTER AS MAIN BAROCLINIC ZONE SETS UP SHOP IN OR JUST SOUTH OF OUR REGION FROM SUNDAY INTO EARLY NEXT WEEK. MOIST SW FLOW AND A FEW SHORTWAVES WILL PROVIDE OPPORTUNITIES FOR PRECIPITATION...THE BEST OF WHICH APPEARS TO BE SUNDAY NIGHT INTO MONDAY AT PRESENT TIME. PRECIPITATION TYPE REMAINS UNCERTAIN THROUGH THIS PERIOD. ENSEMBLES LIKELY WOULD PROVIDE THE PATH OF LEAST REGRET AT THIS POINT. NEVERTHELESS...THE RISING H500 HEIGHTS POINT TO TEMPERATURES AT LEAST GETTING WITHIN THE REALM OF SEASONABLE VALUES BY THE END OF THE EXTENDED PERIOD. CL && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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A COLD FRONT WILL CROSS THE REGION EARLY THIS MORNING...WITH THE BIGGEST IMPACT BEING A SEVERAL HOUR PERIOD OF MVFR CIGS. BASED ON LATEST MODEL SOUNDINGS...CIGS SHOULD IMPROVE TO LOW VFR LEVELS BY LATE MORNING/EARLY AFTERNOON...HOWEVER...CONFIDENCE OF THIS OCCURRING IS ONLY ABOUT 60%. LIGHT SNOW MAY ACCOMPANY THE FRONT...MAINLY ACROSS NORTHERN SITES...BUT IMPACTS WILL BE MINIMAL. OUTLOOK.../WEDNESDAY THROUGH SUNDAY/... RESTRICTIONS ARE POSSIBLE AREA WIDE WITH A LATE THURSDAY DISTURBANCE SOUTH OF PIT. RESTRICTIONS WILL ALSO BE POSSIBLE SUNDAY WITH AN APPROACHING COLD FRONT.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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