Area Forecast Discussion
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000 FXUS61 KPBZ 141740 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 140 PM EDT MON APR 14 2014 .SYNOPSIS...
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A STRONG COLD FRONT WILL BRING SHOWERS AND A FEW ISOLATED STORMS TO THE AREA LATER THROUGH THE NIGHT. MUCH COLDER AIR WILL MOVE IN ON TUESDAY WITH THE CHANCE FOR SNOW SHOWERS.
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&& .NEAR TERM /THROUGH TUESDAY/...
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AN AREA OF SHOWERS CURRENTLY EXTENDS ACROSS MOST OF EASTERN OHIO IN ASSOCIATION WITH WEAK ASCENT AHEAD OF A COLD FRONT THAT IS SLICING THROUGH WESTERN OHIO AT THE MOMENT. ONE SURFACE WAVE DOWN THIS FRONT HAS MOVED NORTHWARD THROUGH THE DAY ALONG THE FRONT AND IS HELPING TO ACCENTUATE LIFT AND FOCUS INSTABILITY ALONG THE FRONT WEST OF CLEVELAND AND NORTHWARD INTO LAKE ERIE INTO A LINE OF FAIRLY IMPRESSIVE SHOWER DEVELOPMENT. LUCKILY ENOUGH FOR US...THIS WAVE ALONG THE FRONT WILL CONTINUE NORTHEASTWARD...WITH ONLY ENHANCED MOISTURE ADVECTION AND WEAK LIFT LIKELY TO GENERATE SHOWERS FROM WEST TO EAST ACROSS THE AREA LATE THIS AFTERNOON AND EARLY EVENING. A SECOND WAVE ALONG THE FRONT DEVELOPS IN THE RIGHT ENTRANCE REGION OF A DEVELOPING UPPER LEVEL JET STREAK LATE THIS EVENING AND TRACKS BASICALLY RIGHT OVER PITTSBURGH AFTER MIDNIGHT. LIFT IN ASSOCIATION WITH THIS WAVE WILL GENERATE A SECOND AREA OF SHOWERS THAT WILL LIKELY MOVE THROUGH THE AREA OVERNIGHT FROM SOUTHWEST TO NORTHEAST. IT IS BEHIND THIS WAVE THAT THE FLOW WILL FINALLY TURN AROUND TO THE NORTHWEST AND ALLOW THE MUCH ADVERTISED COLD FRONT TO TRUDGE EAST OF THE REGION THROUGH THE MORNING HOURS OF TUESDAY. DRASTICALLY COLDER AIR MOVES INTO THE REGION...UNDERCUTTING THE WARMER/MORE MOIST AIR. THIS WILL ALLOW FOR PRECIPITATION TO LIKELY TO CONTINUE AS THE MOIST AIR IS EVACUATED THROUGH THE MORNING...WHICH WILL SLOWLY TREND THE P-TYPE TOWARD SNOW FROM NORTHWEST TO SOUTHEAST. BECAUSE OF THERMAL PROFILES AND WARM AIR ALOFT...A PERIOD OF SLEET CERTAINLY WOULD NOT BE OUT OF THE QUESTION. HOWEVER...WHILE MOST AREAS SHOULD START TO CHANGE TO SNOW BY AFTERNOON...ACCUMULATIONS SHOULD BE MINIMAL GIVEN MARGINAL AIR TEMPERATURES AND UNFAVORABLE GROUND TEMPERATURES DUE TO RECENT WARMTH. FOR THE RIDGES...AS THE PROFILES COOL BY LATE AFTERNOON...LAPSE RATES WILL STRENGTHEN IN THE LOW LEVELS WHILE MOISTURE REMAINS. IT WILL TAKE VIRTUALLY ALL DAY FOR THE LOW LEVEL PROFILE TO COOL BELOW FREEZING...HOWEVER BY LATE AFTERNOON WITH THE TOP OF THE SATURATED LAYER LIKELY INTERSECTING THE BOTTOM OF THE DENDRITIC GROWTH LAYER...SNOWFALL RATES SHOULD START TO PICK UP ENOUGH TO ALLOW FOR SOME ACCUMULATION. FRIES
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&& .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... FRONT SLOWLY MOVES THROUGH THE AREA LATE TONIGHT/EARLY TUESDAY MORNING. THE CONVECTIVE THREAT WILL DECREASE TONIGHT AND WINDS WILL RELAX. MOST OF THE PRECIPITATION WILL MOVE THROUGH DURING FRONTAL PASSAGE. MUCH COLDER AIR WILL QUICKLY RUSH IN BEHIND THE FRONT...WHICH SHOULD BE COLD ENOUGH TO CHANGE POST FRONTAL RAIN SHOWERS TO SNOW SHOWERS. LOOKING WESTWARD...FRONT IS SEPARATING A WIDE RANGE OF TEMPS WITH READINGS EAST OF THE FRONT IN THE MID 60S TO TEMPERATURES BEHIND THE FRONT IN THE UPPER 30S TO MID 40S. LOW CONFIDENCE IN THE CURRENT AMOUNT OF QPF MODELS ARE CREATING BEHIND THE FRONT. AT THIS TIME...IT LOOKS AS IF THERE IS A PERIOD DIRECTLY BEHIND THE FRONT WHERE THE MODELS ARE OVER DOING THE AMOUNT OF LIFT. THIS SHORT PERIOD OF STRONG OMEGA IS LIKELY CAUSING AN OVER AMPLIFICATION OF QPF AMOUNTS TUESDAY MORNING. TEMPS WILL BE VERY TRICKY ON TUESDAY...LATEST MODEL SOUNDINGS ARE INITIALLY SHOWING A RAPID DROP OF SURFACE TEMPERATURES WITH FROPA...AS A SHALLOW LAYER OF LOW LEVEL COLD AIR SETTLES IN. THIS FEATURE SHOWS UP WELL WITH AN EXAMINATION OF LAYERED THICKNESSES. LOW LEVEL THICKNESS WILL BECOME COLD ENOUGH FIRST TO SUPPORT SNOW...HOWEVER THE COLD MID LEVEL THICKNESSES ARE LAGGING BEHIND BY ABOUT 3 HOURS. THIS SETUP WOULD LIKELY PRODUCE A MIX OF RAIN AND SNOW WHICH WOULD EVENTUALLY CHANGE TO ALL SNOW. THE OTHER QUESTION IS HOW FAR DO TEMPS DROP AND WILL THERE BE ANY RECOVERY DURING THE DAY WITH STRONG CAA ONGOING THROUGHOUT THE DAY. THE NEXT HEADACHE WILL ARRIVE LATE TUESDAY AFTERNOON THROUGH TUESDAY EVENING. VERY COLD AIR WILL CROSS THE GREAT LAKES AND STRONG WINDS ALOFT WILL BE OUT OF THE NORTHWEST. THE MAIN SHORTWAVE TROUGH SWINGS THROUGH DURING THIS TIME AND MODELS ARE HINTING AT A PERIOD OF LAKE EFFECT/ENHANCED SNOW SHOWERS. INVERSIONS TUESDAY EVENING ARE PLENTY DEEP ENOUGH TO SUPPORT LES. INVERSIONS QUICKLY DROP TUESDAY NIGHT AS WINDS ALOFT VEER TO THE NORTH AND A STRONG SURFACE HIGH WILL BUILD IN FROM THE WEST. THIS WILL BRING A QUICK END TO ANY SNOW SHOWERS THAT DEVELOP. COLD AIR WILL EVACUATE TOWARD THE NORTH WEDNESDAY...THIS WILL ALLOW FOR A QUICK DECREASE IN CLOUD COVER AND A MODERATION IN TEMPS. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... A RETURN TO SPRING FOR THE LONG TERM...WITH THE RISK FOR SHOWERS FRIDAY NIGHT/SAT. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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VFR CONDITIONS WILL PREVAIL AHEAD OF THE SHOWERS THAT ARE MOVING INTO THE REGION THIS AFTERNOON. WIDESPREAD GUSTY SW WINDS WILL TREND TOWARD THE WEST AS A COLD FRONT APPROACHES OVERNIGHT. A WAVE ALONG THE FRONT WILL ALLOW FOR A SECONDARY INCREASE IN SHOWER DEVELOPMENT LATE THIS EVENING AND OVERNIGHT...WHICH SHOULD TREND ALL SITES FROM MVFR TOWARD IFR BY MORNING. THEN MUCH COLDER AIR MOVES IN...WINDS TURN NW AND BECOME GUSTY. PRECIP SHOULD TREND TOWARD SNOW SHOWERS BY TUESDAY AFTERNOON UNDER CONTINUED IFR CONDITIONS. FRIES .OUTLOOK.../TUESDAY NIGHT THROUGH FRIDAY/... SOME RESTRICTIONS ARE EXPECTED UNTIL LOW LEVEL MOISTURE GETS REMOVED FROM THE AREA...WHICH WILL LIKELY TAKE UNTIL WEDNESDAY.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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