Area Forecast Discussion
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000 FXUS61 KPBZ 012138 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 538 PM EDT FRI AUG 1 2014 .SYNOPSIS... TEMPERATURES WILL MOVE TO NEAR AVERAGE WITH CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH SUNDAY. DRY AND MILD CONDITIONS TO RETURN BY THE BEGINNING OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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SHOWER AND THUNDERSTORM ACTIVITY IS HAVING DIFFICULTY MAINTAINING ITSELF THIS EVENING...AS WEAK SHEAR IS FAILING TO EVACUATE ENOUGH MASS FROM THE COLUMN TO ASSIST IN CONSISTENT UPDRAFT FORMATION BEFORE VERTICAL MOTION BECOMES AFFECTED BY SPREADING COLD POOLS BELOW STORMS. EARLIER COLLAPSING STORMS OVER THE SOUTHEASTERN CWA AND RIDGES HAVE MANAGED TO PRODUCE WHAT IS NOW A COHERENT OUTFLOW STRUCTURE EMANATING WESTWARD FROM THE COMBINED COLD POOL INTO AN ARC FROM ROUGHLY KITTANNING TO PITTSBURGH TO FAIRMONT AT THIS HOUR. INCIPIENT UPDRAFT FORMATION IS MANAGING TO ALLOW FOR SOME ADDITIONAL SHOWER/STORM DEVELOPMENT ALONG THE INTERFACE BETWEEN SAID COLD POOL AND THE MORE UNSTABLE ATMOSPHERE TO ITS WEST...HOWEVER HERE AGAIN...THE MOVEMENT OF THE COLD POOL TO THE WEST SHOULD CONTINUE TO UNDERMINE CONTINUED UPDRAFT FORMATION OF THESE NEW CELLS. AS A RESULT...JUST SCATTERED TO ISOLATED ACTIVITY IS LIKELY TO CONTINUE TO REDEVELOP FARTHER TO THE WEST AND NORTH IN THE CWA AS THIS BOUNDARY TRANSITS AND WEAKENS THROUGH THE EVENING HOURS. FRIES
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... SHORTWAVE DIGGING THROUGH THE UPPER TROUGH WILL MAKE IT`S APPROACH LATE ON SATURDAY. WHILE THE DEEPEST MOISTURE WILL REMAIN SHUNTED BY THE HIGHER TERRAIN TO THE EAST...THE APPROACHING SHORTWAVE SHOULD PROVIDE ENOUGH LIFT TO SET OFF SHOWERS AND STORMS ACROSS MOST OF THE FORECAST AREA BY SATURDAY AFTERNOON. SINCE THE LOW-MID LEVEL FLOW WILL REMAIN RATHER WEAK...AND BUFKIT SOUNDINGS HAVE VERY UNIMPRESSIVE INSTABILITY VALUES...DO NOT ANTICIPATE A SEVERE THREAT. ACTUALLY QUESTION THE EXTENT OF THUNDER AS CLOUD COVER COULD FURTHER LIMIT DESTABILIZATION. PWAT VALUES WILL ALSO REMAIN UNDER 1.5 INCHES...SO HEAVY RAIN IS NOT ANTICIPATED EXCEPT IN ANY SLOW MOVING STORMS. SHORTWAVE WILL TAKE ITS TIME CROSSING THE REGION...MAINTAINING THE CHANCE FOR SHOWERS AND A FEW STORMS INTO SUNDAY. BY MONDAY...MOST OF THE MOISTURE WILL BE WELL EAST OF THE REGION...WITH SUBSIDENCE TAKING PLACE FURTHER WEST. WILL KEEP SLIGHT CHANCE POPS IN THE FORECAST FOR THE RIDGES HOWEVER. TEMPERATURES WERE A BLEND OF MEX/MET VALUES THROUGH THE PERIOD. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... UPPER TROUGH WILL REMAIN SETTLED OVER THE EASTERN CONUS THROUGH THE BULK OF THE LONG TERM...SHIFTING EASTWARD BY LATE IN THE PERIOD. MODELS HAVE A WEAK COLD FRONT DROPPING SOUTHWARD OUT OF THE GREAT LAKES LATE TUESDAY INTO WEDNESDAY BUT AT THIS POINT IT LOOKS RATHER MOISTURE STARVED. AFTER THIS...THE MODEL SOLUTIONS DIVERGE. OPTED TO MAINTAIN LOW CHANCE POPS THROUGH MUCH OF THE PERIOD...INCREASING CHANCES LATE AS THE LOW LEVEL FLOW TURNS MORE SOUTHWESTERLY. TEMPERATURES WILL REMAIN RIGHT AROUND SEASONAL AVERAGES THROUGH THE PERIOD. && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/... VFR FOR THE BALANCE OF THE AFTERNOON AND EVENING AWAY FROM ANY SHRA/TSRA...WHICH COULD PROVIDE A BRIEF DROP TO IFR VSBY AT ANY TERMINAL THAT GETS HIT. ELECTED TO KEEP VCTS MENTION AS ANY RESTRICTIONS WILL BE BRIEF AND HARD TO TIME. WENT WITH MVFR FOG OVERNIGHT AT WORST DUE TO LINGERING CLOUDS...BUT WOULD NOT BE SURPRISED IF A LOCATION GETS CLEARING AND THUS IFR LATE. CONDITIONS IMPROVE TO VFR BY 15Z...BUT VCTS ENTERS THE PICTURE AGAIN AROUND MIDDAY. OUTLOOK.../FRIDAY NIGHT THROUGH TUESDAY/... A LOW PRESSURE SYSTEM COULD BRING RESTRICTIONS THROUGH THE BALANCE OF THE WEEKEND. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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