Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPBZ 052152 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 552 PM EDT SUN JUL 5 2015 .SYNOPSIS...
-- Changed Discussion --
A PASSING UPPER LEVEL DISTURBANCE WILL BRING INCREASING RAIN CHANCES TONIGHT AND MONDAY. UNSETTLED WEATHER WILL CONTINUE INTO MIDWEEK WITH AN APPROACHING COLD FRONT.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH MONDAY/...
-- Changed Discussion --
MADE AN UPDATE THIS EVENING TO ADJUST POPS SLIGHTLY BASED ON CURRENT RADAR TRENDS AND HI RES MODEL GUIDANCE. THERE SEEMS TO BE ENOUGH INSTABILITY EARLY THIS EVENING TO SUPPORT THUNDERSTORM DEVELOPMENT ALONG THE RIDGES BUT WITH VERY WEAK STEERING FLOW...THESE STORMS MAY MOVE VERY LITTLE. THIS IS ALREADY APPARENT IN THE CELLS THAT DEVELOPED IN GARRETT COUNTY. WITH PWAT VALUES EXPECTED TO INCREASE AS THE LOW APPROACHES...WILL HAVE TO WATCH FOR CONTINUED DEVELOPMENT OVER THE SAME AREA UNTIL DIURNAL HEATING WANES. WITH EXPANSIVE CLOUD COVER OVERNIGHT...HAVE MADE NO ADJUSTMENTS TO TEMPERATURES AT THIS TIME...AS LOWS LOOK TO STAY ELEVATED IN THE 60`S. PREVIOUS... SLOW-MOVING AND WELL-DEFINED UPPER LEVEL LOW CURRENTLY IN EASTERN KY WILL GRADUALLY FILL AS IT TRUDGES NORTHEASTWARD INTO THE CENTRAL APPALACHIANS THROUGH MONDAY. PROGRESS WILL BE SLOW UNTIL SYSTEM IS KICKED NORTHEAST AHEAD OF THE TUESDAY FRONT. MODELS ARE IN GOOD AGREEMENT WITH THE OVERALL PROGRESS OF THIS SYSTEM. POPS SLOWLY INCREASE TONIGHT FROM THE SOUTH WITH THE APPROACH OF THE UPPER LOW. 1.5+ INCH PWAT VALUES OVERSPREAD THE AREA...BUT MEAGER SUPPORT FOR LIFT WILL KEEP COVERAGE LOW OVERNIGHT...SAVE FOR THE SOUTHEAST RIDGES WITH MOIST UPSLOPE FLOW. BY MONDAY...LOW LEVEL LAPSE RATES WILL STEEPEN ENOUGH TO ALLOW FOR MORE COVERAGE OF SHRA AND TSRA DURING THE DAY. CONTINUED SOUTHEAST FLOW INTO THE RIDGES WILL ENHANCE COVERAGE THERE...THUS THE HIGHER LIKELY AND CATEGORICAL POPS. ANY THUNDERSTORMS WILL BE UNIMPRESSIVE...WITH CAPE BELOW 1000 J/KG AND LITTLE SIGNIFICANT FLOW ALOFT. REDUCED DIURNAL RANGE OF TEMPERATURES OVER THE NEXT 24 HOURS...HIGHER MIN TEMPS AND LOWER MAX TEMPS...WITH CLOUDS AND MOISTURE INCOMING. STILL CLOSE TO SEASONABLE LEVELS.
-- End Changed Discussion --
&& .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 /22Z SUNDAY 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 THROUGH THE EVENING...AND THUS NOT IMPACT TAF SITES...ALTHOUGH MGW WILL BEAR WATCHING. SOME SPOTTY MAINLY MVFR FOG IS POSSIBLE OVERNIGHT...CLOUDS AND A SLIGHTLY STIRRED BOUNDARY LAYER SHOULD KEEP THIS FROM BECOMING DENSE. LOW PRESSURE SYSTEM APPROACHING FROM THE SOUTH WILL SPREAD SHRA AND A FEW TSRA MAINLY EAST OF PIT 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. && $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.