Area Forecast Discussion
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774 FXUS61 KPBZ 042209 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 509 PM EST THU FEB 4 2016 .SYNOPSIS... SEASONABLE TEMPERATURES ARE EXPECTED INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... LOW LEVEL FLOW WILL TURN MORE NORTHWESTERLY A BIT LATER THIS EVENING...INCREASING THE OVER-LAKE MOISTURE FETCH. HOWEVER...EVEN AS THIS OCCURS AND THE INVERSION HEIGHTS RISE A TOUCH DUE TO COLDER AIR ALOFT WITH THE MID-LEVEL TROUGH AXIS SWINGING THROUGH...REAL DIFFICULTY SEEMS TO BE HAD IN TERMS OF THE UNSTABLE BOUNDARY LAYER TOP COOLING ENOUGH TO GET TOWARD THE DENDRITIC GROWTH ZONE. THAT SAID...LIKELY COINCIDENT WITH THE TROUGH AXIS PASSAGE...THERE IS A BRIEF PERIOD WHERE THERE MAY BE ENOUGH INSTABILITY AND MOISTURE DEPTH TO DRIVE A FEW FLURRIES ACROSS MOST OF THE AREA. IN THE FAR NORTHERN REACHES OF THE AREA...SUCH AS NORTH OF I-80...A FEW HOURS OF NEARLY UNIDIRECTIONAL FLOW DOES MANAGE TO BISECT THE LOWER END OF THE DENDRITIC GROWTH LAYER. HOWEVER...GROUND TEMPERATURES WILL BE UNLIKELY TO BE CONDUCIVE TO ACCUMULATION...SO NOTHING MORE THAN A LIGHT DUSTING SEEMS LIKELY THERE. ALSO...IN THE RIDGES...A BIT LONGER PERIOD OF UPSLOPE NORTHWESTERLY FLOW WITH COLDER TEMPERATURES MAY ALLOW FOR UP TO A HALF OF AN INCH IN A FEW SPOTS. HOWEVER...BY DAYTIME ON FRIDAY...ALL OF THIS ACTIVITY SHOULD BE WINDING DOWN AS DRIER AIR WILL BE MOVING IN FROM THE WEST...ALLOWING FOR CRASHING INVERSION HEIGHTS AND AN INHIBITIVE BOUNDARY LAYER PROFILE. FRIES && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/... COLDER AIR WILL PULL BACK TO THE NORTH ON FRIDAY AS RIDGING BUILDS IN OVER THE UPPER OHIO VALLEY. THIS WILL ALLOW FOR A DECREASE IN CLOUD COVER AND ANOTHER DAY OF NEAR NORMAL TEMPERATURES. SATURDAY WILL BE DRY WITH INCREASED CLOUD COVER DURING THE AFTERNOON. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A WEAK COLD FRONT WILL CLIP THE AREA SATURDAY NIGHT...BUT THE HEART OF THE COLD AIR WILL REMAIN NORTH OF THE AREA. A SHORTWAVE TROUGH WILL QUICKLY SWING THROUGH WITH THE SURFACE BOUNDARY...SO THIS MAY PROVIDE ENOUGH LIFT FOR SCATTERED SNOW SHOWERS ACROSS THE NORTH. AFTER A DRY PERIOD SUNDAY...A LARGE TROUGH ACROSS THE EASTERN UNITED STATES WILL BRING WIDESPREAD CLOUDS...SCATTERED RAIN/SNOW SHOWERS...AND EVENTUALLY COLDER TEMPERATURES. MODELS CONTINUE TO WRESTLE WITH THE DETAILS THROUGH THE PERIOD. THE LONG TERM WAS CONSTRUCTED USING THE SUPERBLEND. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... CIGS WILL HOVER AROUND THE 3000FT MARK THIS AFTERNOON INTO THIS EVENING...WITH ALL LOCATIONS EXPECTED TO HAVE MVFR CIGS OVERNIGHT. AS WINDS PICK UP AFTER MIDNIGHT CLOUDS WILL BEGIN TO SLOWLY SCATTER OUT FROM WEST TO EAST...WITH CEILINGS REMAINING THE LONGEST AT FKL/DUJ. MAJORITY OF SITES SHOULD BE VFR BY MID FRIDAY MORNING. MVFR CIGS WILL OVERSPREAD THE REGION THIS MORNING AND CONTINUE INTO THE AFTERNOON. WITH SOME MIXING EXPECT AN IMPROVEMENT TO BKN VFR TOWARD EVENING. WINDS WILL GENERALLY BE WEST AROUND 10 KTS. .OUTLOOK.../FRIDAY NIGHT THROUGH TUESDAY/... GENERAL VFR CAN BE EXPECTED THROUGH THE WEEKEND. THE NEXT CHANCE FOR WIDESPREAD RESTRICTIONS WILL BE MONDAY AND TUESDAY WITH A COLD FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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