Area Forecast Discussion
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000 FXUS61 KPBZ 241130 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 630 AM EST MON NOV 24 2014 .SYNOPSIS... GUSTY WINDS TODAY WILL BE FOLLOWED BY A COLD FRONT AND A RETURN TO MUCH COLDER CONDITIONS FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... A FAIRLY STARK DRY SLOT IS EVIDENT ON SATELLITE IMAGERY FOLLOWING THE SPRAWLING UPPER LOW THAT IS MOVING INTO THE CENTRAL GREAT LAKES EARLY THIS MORNING. WIND GUSTS HAVE MANAGED TO MIX DOWN IN THE SUBSIDENCE IN THIS FEATURE VIA A FAIRLY DISCERNIBLE TROPOPAUSE FOLD OVERNIGHT ON THE ORDER OF 20-30 KTS. LUCKILY ENOUGH...THE BEST SUBSIDENCE AND DEEPEST PV PENETRATION INTO THE LOWER ATMOSPHERE HAS ALREADY CROSSED OUR AREA...SO FOR THE MOMENT...WIND GUSTS HAVE TEMPORARILY PEAKED WITHOUT INCIDENT ACROSS THE AREA. YET ANOTHER UPPER LOW IS POISED TO TRAVERSE THE CENTRAL GREAT LAKES BY AFTERNOON. THE UPPER PV FIELD WILL AGAIN BE CONTORTED BY THIS FEATURE AS YET ANOTHER INTRUSION OF HIGH PV AIR IS SET TO DROP THE DYNAMIC TROPOPAUSE GREATLY BY AFTERNOON OVER CENTRAL AND NORTHERN OHIO. THIS IS WELL DEPICTED ON MODEL CROSS SECTIONS VIA A VERY DEEP TROPOPAUSE FOLD THAT IS PULLING THE 1.5 PVU SURFACE DOWN TOWARD AND BELOW 600 MB ON MOST GUIDANCE. SUBSIDENCE BRINGING THIS FEATURE DOWNWARD COMBINED WITH 55-70 KTS OF AVAILABLE MOMENTUM WILL LIKELY ALLOW FOR WIND GUSTS IN EXCESS OF 60 MPH IN PORTIONS OF CENTRAL AND NORTHERN OHIO. HOWEVER...FARTHER TO THE SOUTH AN EAST ACROSS EASTERN OHIO AND THE REMAINDER OF OUR FORECAST AREA...A WEAKER FIELD OF MOMENTUM AND LESS POTENT MECHANISM FOR DOWNWARD MOMENTUM TRANSFER SEEM LIKELY TO ALLOW FOR OUR GUSTS TO TOP OUT AROUND 50 MPH. THIS PUTS US JUST A BIT SHY OF THE CRITERIA FOR A HIGH WIND WARNING...WHICH JIVES VERY WELL WITH THE PREVIOUS FORECAST. AS SUCH...WIND ADVISORIES WILL CONTINUE FOR ALL PORTIONS OF THE AREA. IF ANYWHERE IS TO OVERACHIEVE AN ADVISORY...IT WILL LIKELY BE OUR WESTERNMOST OHIO COUNTIES OR EVEN MERCER COUNTY AS THE HIGHEST AVAILABLE MOMENTUM VALUES ARE IN THE AFOREMENTIONED AREAS DURING MID-AFTERNOON. WINDS WILL LIKELY TAKE A WHILE TO SLOWLY TAPER OFF THIS EVENING WITH SOME LESSER GUSTS CONTINUING INTO THE OVERNIGHT PERIOD. HOWEVER...THE BIGGER STORY WILL LIKELY BE THE THERMAL ROLLER COASTER. WITH EXTREMELY STRONG MIXING AND SUBSIDENCE THIS AFTERNOON ALONG WITH 850 MB TEMPERATURES ON THE ORDER OF +8 TO +10C WITH A FULLY MIXED BOUNDARY LAYER...SOME 70S WILL CERTAINLY BE POSSIBLE SOUTH AND EAST OF PITTSBURGH...PARTICULARLY WITH A FEW SUN BREAKS. HOWEVER...A COLD FRONT RIPS THROUGH IN ASSOCIATION WITH THE STRONGEST WIND GUSTS LATE IN THE AFTERNOON. THIS WILL DROP 850 MB TEMPERATURES INTO THE -4 TO -8C RANGE BY THE OVERNIGHT HOURS. THIS WILL LIKELY DROP SURFACE TEMPERATURES AROUND 35 DEGREES FROM TODAY`S HIGHS TO TONIGHT`S LOWS AND RETURN US TO OUR RECENT COLDER THAN NORMAL TEMPERATURES AFTER A VERY WARM MONDAY. FRIES && .SHORT TERM /TUESDAY THROUGH THURSDAY/... TUES MORNING FLOW REMAINS FROM THE SW...BUT A STOUT INVERSION PROGGED AT H85 WILL HOLD LLVL MOISTURE IN THROUGH AT LEAST MIDDAY. THIS WILL KEEP CLOUDS HOLDING STEADY THROUGH THE DAY. H85 TEMPS IN THE -4C TO -6C RANGE STEEPENS LAPSE RATES IN THE BL ENOUGH TO GENERATE SOME LIGHT SHOWER ACTIVITY. KEEPING POPS MAINLY ALONG AND NORTH OF I-80 DURING THIS TIMEFRAME. BRIEF RESPITE FROM DISTURBED WEATHER TUES EVENING...BUT THE NEXT SYSTEM ARRIVES WEDS MORNING...WITH THE POTENTIAL TO DISRUPT HOLIDAY TRAVEL...ESPECIALLY FOR THOSE HEADED EAST. A DEVELOPING COASTAL LOW WILL TRACK NORTH THROUGH THE MID-ATLANTIC WEDS WITH THE WRN EXTENT OF THE PRECIPITATION SHIELD REACHING SOMEWHERE BETWEEN THE ERN SLOPES OF THE APPALACHIANS TO THE OHIO VALLEY. EXACT PLACEMENT AND AMOUNTS OF PRECIPITATION DEPEND ON THE INTERACTION WITH A CLIPPER-TYPE SYSTEM MOVING OUT OF THE NRN PLAINS. ATTM MODEL SOLNS STILL VARY GREATLY WITH THE NAM BRINGING THE PLAINS SHORTWAVE IN QUICKER...ULTIMATELY PUSHING THE COASTAL LOW EAST OF THE AREA....HOLDING ALL PRECIPITATION ASSOCIATED WITH IT OUT OF OUR RIDGES. THE 00Z ECMWF IS ON THE OPPOSITE END OF THE SPECTRUM ALLOWING THE LOW TO TRACK FURTHER WEST WITH PRECIPITATION SPREADING WEST TO AT LEAST THE OHIO BORDER. WITH THIS MUCH SPREAD...DECIDED TO HOLD ONTO THE SREF AS GUIDANCE...WHICH IS A DECENT COMPROMISE. POPS WERE EXPANDED WESTWARD...HOWEVER...TO SHOW AT LEAST A CHANCE OF PRECIPITATION GETTING WEST OF THE RIDGES. COMPLICATING MATTERS FOR THE MID-WEEK SYSTEM WILL BE TEMPS HOVERING NEAR OR ABOVE FREEZING FOR LOCATIONS RECEIVING PRECIPITATION. ATTM...OPTED FOR A MAV/MOS BLEND FOR HIGHS WEDS...AND APPLIED A LIBERAL RAIN/SNOW DELINEATION...GIVEN THE FAIRLY COLD AIR ALOFT AND A RELATIVELY SHALLOW WARM LAYER NEAR THE SFC. ALL TOLD...THROUGH EARLY THANKSGIVING MORNING...BETWEEN THE COASTAL LOW AND THE CLIPPER...HAVE LIGHT SNOW ACCUMULATIONS FOR THE RIDGES AND LITTLE TO NO SNOW ACCUMULATION ACROSS THE LOWER ELEVATIONS WEST. FOR REFERENCE...THE GFS...WHICH HOLDS A SIMILAR TRACK TO THE 00Z ECMWF MODEL MENTIONED ABOVE...GENERATES AROUND 6" IN THE HIGHEST ELEVATIONS THROUGH WEDS NIGHT. TAX && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... NORTHWEST FLOW AND REMNANT MOISTURE FROM THE EXITING MID-WEEK SYSTEM WILL PRODUCE SNOW SHOWERS THANKSGIVING NIGHT...ENHANCED JUST DOWNWIND OF LAKE ERIE AND IN THE UPSLOPE REGIONS OF OUR SE RIDGES. THESE SHOWERS SHOULD QUICKLY TAPER OFF EARLY FRI...HOWEVER...AS SUBSIDENCE OCCURS WITH HIGH PRESSURE MOVING IN FROM THE WEST. THIS WILL EFFECTIVELY LOWER INVERSION HEIGHTS AND CHOKE OUT THE REMAINING BL MOISTURE BY LATE FRI MORNING. FROM THAT POINT THE EXTENDED PERIOD GETS A LITTLE TRICKY AS MODEL GUIDANCE DIVERGES GREATLY. PRIMARILY STUCK CLOSE TO WPC GUIDANCE BASED HEAVILY ON THE OPERATIONAL GFS. THIS BRIEFLY HOLDS THE SFC HIGH OVER THE AREA INTO THE EARLY PART OF THE WEEKEND BEFORE AN UPPER TROF PROPELS A SFC LOW PRESSURE SYSTEM THROUGH THE NRN GREAT LAKES. THE ASSOCIATED MOISTURE-STARVED COLD FRONT WILL STREAM ACROSS THE FORECAST AREA SUN RESULTING IN SOME SHOWERS. RAISED TEMPS AHEAD OF THE FRONT WHICH MEANS THAT RAIN AND RAIN/SNOW COME INTO PLAY...BUT ANY QPF ASSOCIATED LOOKS LIGHT. TAX && .AVIATION /12Z MONDAY THROUGH FRIDAY/... A LARGE SCALE DRY IS CURRENTLY PUSHING NORTHWARD THROUGH THE AREA EARLY THIS MORNING WITH WINDS GUSTING AND TURNING A BIT MORE SOUTHERLY. BEHIND THIS DRY SLOT...WHILE STRATUS WAS SOMEWHAT PERVASIVE EARLIER...MIXING AND SUBSIDENCE HAS TAKEN ITS TOLL ON THIS STRATUS...ALLOWING FOR SKIES TO START TO BREAK UP SIGNIFICANTLY. THIS WILL ALLOW FOR AT WORST BROKEN SKIES OVER MOST SITES BY LATE MORNING/AFTERNOON. GUSTY SOUTH TO SOUTHWEST WINDS WILL ALSO ARRIVE MORE STRONGLY BY AFTERNOON. WIND GUSTS OVER 40 KTS WILL BE POSSIBLE AT ALL SITES. FRIES OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/... POSSIBLE RESTRICTIONS IN SNOW SHOWERS LATE WEDNESDAY THROUGH THURSDAY. && .CLIMATE...
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RECORD HIGH TEMPERATURES ARE POSSIBLE IN THE REGION TODAY. HERE IS A SUMMARY OF CURRENT FORECAST HIGH TEMPERATURES WITH THE STANDING RECORDS AND YEARS OF RECORD OCCURRENCE. CITY FORECAST RECORD/YEAR PITTSBURGH INTERNATIONAL 71 69/1931 MORGANTOWN 74 72/1979 ZANESVILLE 65 70/2001 NEW PHILADELPHIA 65 71/1979 WHEELING 71 70/2001 DUBOIS 67 61/1979
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WIND ADVISORY FROM 11 AM THIS MORNING TO 10 PM EST THIS EVENING FOR MDZ001. OH...WIND ADVISORY FROM 11 AM THIS MORNING TO 10 PM EST THIS EVENING FOR OHZ039>041-048>050-057>059-068-069. PA...WIND ADVISORY FROM 11 AM THIS MORNING TO 10 PM EST THIS EVENING FOR PAZ007>009-013>016-020>023-029-031-073>076. WV...WIND ADVISORY FROM 11 AM THIS MORNING TO 10 PM EST THIS EVENING FOR WVZ001>004-012-021>023-041. && $$

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