Area Forecast Discussion
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000 FXUS61 KPBZ 060202 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 1002 PM EDT SUN JUL 5 2015 .SYNOPSIS... A PASSING UPPER LEVEL DISTURBANCE WILL BRING INCREASING RAIN CHANCES TONIGHT AND MONDAY. UNSETTLED WEATHER WILL CONTINUE INTO MIDWEEK WITH AN APPROACHING COLD FRONT. && .NEAR TERM /THROUGH MONDAY/... STACKED UPPER LOW OVER EASTERN KENTUCKY WILL SLOWLY LIFT NORTHEASTWARD TOWARD THE REGION OVERNIGHT. AS ANTICIPATED...CONVECTION HAS WANED WITH THE LOSS OF HEATING. WILL STILL KEEP THE CHANCE FOR SHOWERS IN THE SOUTHERNMOST COUNTIES OVERNIGHT...ESPECIALLY NOW THAT THE LOWER LEVELS HAVE BECOME BETTER SATURATED...AND ALONG THE RIDGES WHERE SOUTHEASTERLY FLOW MAY PROVIDE FOR SOME UPSLOPE...BUT TOOK OUT ANY MENTION OF THUNDER. WITH EXPANSIVE CLOUD COVER OVERNIGHT...DO NOT THINK TEMPERATURES WILL FALL OFF MUCH. HAVE OPTED TO STAY CLOSER TO THE WARMER SREF/NAM GUIDANCE. UPPER LOW WILL CONTINUE ITS TREK NORTHEASTWARD DURING THE DAY MONDAY. PWAT VALUES ARE EXPECTED TO INCREASE AND WITH LITTLE STEERING FLOW...SOME HEAVY DOWNPOURS MAY BE POSSIBLE...ESPECIALLY IN THUNDERSTORMS. MODELS TO ONE DEGREE OR ANOTHER HAVE A DRY SLOT WRAPPING INTO THE LOW OVER THE RIDGES IN THE AFTERNOON. THIS MAY BE THE BEST LOCATION FOR THUNDER...BUT MODEL PROFILES HAVE ABOUT 800J/KG ACROSS THE ENTIRE AREA. WILL CONTINUE TO CARRY THE HIGHEST POPS OVER THE RIDGES FOR NOW...BUT IT MAY NEED TO EXPANDED FURTHER NORTH AND WEST. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... AN ACTIVE WEATHER REGIME REMAINS IN PLACE WITH SOUTHEASTERN CONUS RIDGE TRYING TO RE-ESTABLISH PLACING THE UPPER OHIO VALLEY IN THE CORRIDOR OF THE MID LEVEL STEERING FLOW. WHAT IS LEFT OF LOW PRESSURE SLOWLY TRUDGING NORTHEAST FROM TENNESSEE RIVER VALLEY WILL DEPART MONDAY NIGHT. WITH POSITION OF MID LEVEL TROUGH AXIS...OPTED FOR PRECIPITATION PROBABILITIES TO BE HIGHEST OVER PA...NORTHERN WV...AND WESTERN MD MONDAY NIGHT. WITH EASTERN OHIO ON THE WESTERN FLANK AND ANTICYCLONIC DIFFERENTIAL VORTICITY ADVECTION REMOVED POPS FOR THOSE LOCATIONS. TUESDAY FEATURES MAIN WEATHER MAKER OF THE SHORT TERM AS A BAROCLINIC ZONE CROSSES DURING THE LATE EVENING HOURS. 12Z NCEP GUIDANCE HAS SLOWED DOWN FROPA A FEW HOURS WITH IT CROSSING AFTER MIDNIGHT. SEVERAL CONVECTIVE ALLOWING MODELS PORTRAY A LINE OF SHOWERS AND THUNDERSTORMS DEVELOPING OVER OHIO AND WEST VIRGINIA AFTER 21Z TUESDAY THEN MOVE THEM THROUGH OUR REGION. SBCAPE VALUES SURPASS 2.5 KJKG-1 HOWEVER WITH MODEL DEWPOINTS PROGGED IN THE LOWER 70S...CAPES ARE INFLATED. SHEAR ON THE OTHER HAND IS NOT TOO IMPRESSIVE WITH 0-3KM WINDS AROUND 35 KTS. LOW LEVEL LAPSE RATES ARE MODEST PEAKING OUT AROUND 6.5CKM-1. WITH ALL THAT INFORMATION...POTENTIAL IS THERE FOR STRONG TO POSSIBLY SEVERE STORMS TUESDAY EVENING. THE AMOUNT OF SUNSHINE OR LACK THEREOF WILL BE A DECIDING FACTOR IN COVERAGE AND INTENSITY. STILL TOO MUCH UNCERTAINTY TO WARRANT AN INCLUSION IN THE HAZARDOUS WEATHER OUTLOOK AT THIS TIME. DID INCREASE POPS AS CONFIDENCE IS HIGHER IN AT LEAST MEASURABLE RAINFALL. BOUNDARY STALLS EARLY WEDNESDAY MORNING SOMEWHERE IN THE VICINITY OF I-70 BEFORE RETREATING NORTH DURING THE DAY DUE TO ANTICYCLONE BUILDING OVER THE SOUTHEASTERN UNITED STATES. THIS WILL CREATE A WINDOW FOR SHOWERS AND THUNDERSTORMS MAINLY NORTH OF THE AFOREMENTIONED INTERSTATE DEMARCATION. POINTS SOUTH COULD SEE A POP UP SHOWER OR STORM DUE THE AMOUNT OF MOISTURE PRESENT. MOST OF THE UPPER LEVEL DIVERGENCE IS FORECAST NORTH OF LAKE ERIE AND THUS WILL ANY ORGANIZED ACTIVITY MID WEEK. PWATS SURPASS 2.0 INCHES TUESDAY NIGHT INTO WEDNESDAY COUPLED WITH A WARM CLOUD DEPTH IN EXCESS OF 11KFT RESULTING IN POSSIBLE DOWNPOURS. TEMPERATURES WERE A BLEND OF THE EXISTING FORECAST AND THE ADJUSTED ECMWF GUIDANCE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... MODEL ENSEMBLE PROGS CONTINUE TO SHOW A GENERAL ZONAL FLOW THROUGH THE PERIOD...WITH PERIODIC CROSSING SHORTWAVES BRINGING OCCASIONAL SHOWER AND THUNDERSTORM CHANCES. OPTED FOR WPC ENSEMBLE BASED GUIDANCE TO SMOOTH OUT OPERATIONAL MODEL DIFFERENCES. MAIN ADJUSTMENTS TO THIS GUIDANCE WERE FOR DOWNWARD POP ADJUSTMENTS AND UPWARD TWEAKS TO THE EXPECTED SEASONALLY WARM TEMPERATURES. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... VFR CONDITIONS FOR THE MOST PART THROUGH THE EVENING HOURS WITH LOWERING HIGH CLOUDS. EXPECTING ANY SHRA/TSRA TO BE CONFINED MAINLY TO THE WV/MD RIDGES AND KMGW AREA THROUGH THE EVENING HOURS. SOME SPOTTY MAINLY MVFR FOG IS POSSIBLE OVERNIGHT...CLOUDS AND A SLIGHTLY STIRRED BOUNDARY LAYER SHOULD KEEP THIS FROM BECOMING TOO WIDESPREAD. LOW PRESSURE SYSTEM APPROACHING FROM THE SOUTH WILL SPREAD SHRA AND A FEW TSRA MAINLY EAST OF KZZV FROM MIDMORNING MONDAY ON...ALTHOUGH ANY LOCATION MAY RECEIVE A SHOWER. KEEPING LOW VFR CIGS FOR NOW ALTHOUGH TEMPO MVFR/IFR MAY NEED TO BE ADDED PENDING FUTURE TRENDS. .OUTLOOK.../MONDAY THROUGH THURSDAY/... PERIODIC RESTRICTIONS ARE POSSIBLE THROUGH THE PERIOD WITH SEVERAL CROSSING DISTURBANCES. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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