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
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPBZ 130808 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 408 AM EDT SUN JUL 13 2014 .SYNOPSIS... A SERIES OF COLD FRONT WILL BRING SHOWERS AND STORMS TO THE AREA THROUGH EARLY TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... ATMOSPHERE WILL QUICKLY DESTABILIZE THIS MORNING...AS MOISTURE LEVELS INCREASE DUE TO THE A STRONG SOUTH-SOUTHWESTERLY FLOW. MODEL SOUNDINGS ARE SHOWING A LOW LEVEL INVERSION HOLDING UNTIL AROUND 14 OR 15Z WHICH WILL CAP THE LOWER LEVELS OF THE ATMOSPHERE. AS THE AFTERNOON APPROACHES...A SHORTWAVE TROUGH WILL SWING THROUGH FOLLOWED QUICKLY BY A WEAK COLD FRONT. THE BEST TIME FOR STRONG TO SEVERE DEVELOPMENT LOOKS TO BE WITH THE PASSAGE OF THIS SURFACE BOUNDARY. STRONG LINE OF LOW LEVEL MOISTURE CONVERGENCE AND FORCING WILL DEVELOP AHEAD OF THE FRONT. ATMOSPHERE WILL BE PLENTY BUOYANT WITH SURFACE CAPES OF 2000-2500 J/KG AND SHEAR VALUES WILL BE 35 TO 45 KTS...STRONG ENOUGH TO PROMOTE ORGANIZED DEVELOPMENT. IN ADDITION TO THE INSTABILITY...PWAT VALUES OF UP TO 2 INCHES WILL PROVIDE THE THREAT FOR HEAVY DOWNPOURS. THERE WILL BE LIMITING FACTORS HOWEVER...TEMPS ALOFT ARE VERY WARM AND WITH THE CLOUD COVER AHEAD OF THE FRONT...WE MAY FIND IT DIFFICULT TO REACH CONVECTIVE TEMPS. THE SLIGHT RISK IN PLACE LOOKS REASONABLE. AS FRONT DRAGS SOUTHEASTWARD THIS AFTERNOON IT WILL LOSE MUCH OF ITS PUNCH AS THE MOISTURE CONVERGENCE AND FORCING DISSIPATES. ATMOSPHERE WILL STABILIZE AS THE EVENING APPROACHES AND THE LINE OF SHORTWAVES WILL MOVE INTO NORTHERN WEST VIRGINIA. THE OVERALL SETUP POINTS TO A LINE OF CONVECTION DEVELOPING RIGHT ALONG THE FRONT AND WEAKENING AS IT MOVES SOUTHWARD. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... CONVECTION WILL WEAKEN OVERNIGHT AND THE THREAT FOR HEAVY RAIN SHOULD DECREASE AS WELL. THE FRONT WILL BE DIFFICULT TO FIND LATER TONIGHT...BUT IT DOES APPEAR THAT IS WILL STALL OVER THE SOUTHERN HALF OF THE FA. MODELS ARE HINTING AT A SECOND COMPLEX DEVELOPING AS DAWN APPROACHES MONDAY MORNING ALONG THE STALLED BOUNDARY. THIS CURRENTLY GIVES ME PAUSE AS THE MAIN UPPER LEVEL SUPPORT WILL BE WELL TO THE SOUTH BY THIS TIME AND THE REAL UNSTABLE AND MOIST AIR WILL ALSO BE SHOVED SOUTHWARD. ITS POSSIBLE THAT AN MCS COULD DEVELOP OVER THE LOWER OHIO VALLEY AND THEN SPREAD EASTWARD ALONG THE BOUNDARY. IF THIS SECOND COMPLEX DEVELOPS...HIGH WATER MAY BECOME A CONCERN. MONDAY`S FORECAST STILL REMAINS MUDDLED AS FOCUS EARLY WILL BE ON THE STALLED FRONT OVER THE SOUTH AND THEN SHIFT TO THE PASSAGE OF A SECONDARY FRONT FROM THE NORTHWEST MONDAY NIGHT. STILL SOME TIMING ISSUES WITH THE PASSAGE OF THE SECOND FRONT AND HOW MUCH ADDITIONAL ACTIVITY WILL DEVELOP AHEAD OF IT. WILL NEED TO LEAVE IN AT LEAST HIGH CHANCE POPS INTO EARLY TUESDAY. FRONT WILL FINALLY CLEAR EARLY TUESDAY AS A STRONG SHORTWAVE TROUGH MOVES INTO THE UPPER OHIO VALLEY. SHOWERS TUESDAY MORNING SHOULD BE CONFINED TO THE EAST...BEFORE EXITING BY THE AFTERNOON. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... DRIER AND MUCH COOLER AIR WILL SETTLE IN TUESDAY NIGHT. BROAD CANADIAN HIGH WILL KEEP THE AREA DRY AND COMFORTABLE THROUGH THE REMAINDER OF THE LONG TERM. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... VFR CONDS EXPD THRU TNGT WITH INCRG AC/CI. AN ADVNG SHRTWV WL CROSS THE AREA SUN WITH SHWRS AND TSTMS EXPD TO DVLP THRU THE DAY...WITH SITES FM PIT S NOT EXPG CNVCTN UNTIL MID TO LT AFTN. WL MAINTAIN A VCTS OR TSTM MENTION IN THE TAFS FOR THE MOST LIKELY TIME OF CNVCTN. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... OCNL RSTRNS WL BE PSBL UNTIL THE PASSAGE OF A MON NGT-TUE CDFNT. && .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.