Area Forecast Discussion
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000 FXUS61 KPBZ 190504 AAC AFDPBZ AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PITTSBURGH PA 104 AM EDT TUE AUG 19 2014 .SYNOPSIS... A SERIES OF DISTURBANCES WILL KEEP SHOWER AND THUNDERSTORM CHANCES IN THE FORECAST THROUGH THE WEEK. && .NEAR TERM /THROUGH TODAY/... SOME MINOR CHANGES TO OVERNIGHT. INCREASED CLOUD COVER WITH MODELS SHOWING AN INCREASE IN LOW/MID LEVEL MOISTURE. STARTING TO SEE THIS ON LATEST SAT PICS. HAVE ADJUSTED POPS AND TEMPS WITH LATEST GUIDANCE. APPEARS MOST OF THE DAY SHOULD BE QUIET WITH ZONAL FLOW ALOFT AND NO UPPER LEVEL WAVES EXPECTED. COULD SEE SOME SHOWERS/STORMS DEVELOP ALONG THE RIDGES WITH UP-SLOPE FLOW. HIRES MODELS ARE HINTING AT LOW LEVEL MOISTURE POOLING THIS AFTERNOON AND WITH DAYTIME HEATING...WILL NEED TO INCLUDE POPS. WILL BRING A SLOW INCREASE IN POPS TO THE REST OF THE AREA VERY LATE IN THE DAY AS MODELS CONTINUE TO SHOW AN MCS DEVELOPING TO THE WEST WITH THE NEXT SHORTWAVE TROUGH. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... CONTINUES TO LOOK LIKE AN MCS WILL MOVE THROUGH TONIGHT. DO FEEL THAT MODELS...PARTICULARLY THE NAM...MAY BE OVERPLAYING THE INTENSITY OF THE COMPLEX AND MAY BE JUST A BIT FAST. SEEING A LOT OF CONVECTIVE FEEDBACK IN THE NAM QPF SOLUTIONS LIKELY DUE TO THE FORECASTED INTENSITY OF THE SHORTWAVE. ATMOSPHERE IS NOT PARTICULARLY UNSTABLE OVERNIGHT AS THE THE REAL JUICY AIR REMAINS TO THE WEST ON THE OTHER SIDE OF A STALLED BOUNDARY. IN THE SMALLER SCALE...NAM IS SHOWING VERY STRONG LOW LEVEL MOISTURE CONVERGENCE AND FORCING RIGHT AHEAD OF THE WAVE...LEADING ME TO BELIEVE THAT IT IS TRYING TO FORCE THE BOUNDARY EASTWARD. HOWEVER...IT APPEARS THAT FRONTAL INFLUENCE WILL DISSIPATE QUICKLY AS IT RUNS INTO LOW LEVEL SUBSIDENCE FROM EASTERN HIGH. WILL NEED TO KEEP AN EYE ON THE OVERNIGHT PERIOD IN FUTURE FORECASTS. FEEL MARGINALLY CONFIDENT THAT WIDESPREAD SHOWERS WILL MOVE THROUGH... BUT AT THIS POINT...WILL NOT OVERPLAY A SEVERE THREAT. WILL ALSO NEED TO WATCH HOW THE AIR-MASS EVOLVES TODAY. IF THE HIGH SURFACE TDS DO MAKE IT FURTHER EAST...HEAVY DOWNPOURS WILL BE A THREAT OVERNIGHT. WAVE MOVES EAST WEDNESDAY MORNING...ALLOWING THE JUICY AIR TO THE WEST TO SHIFT EASTWARD. ATMOSPHERE DESTABILIZES IN RESPONSE TO THIS CONTINUING THE THREAT FOR SHOWERS AND STORMS. IT IS LIKELY THAT A BOUNDARY WILL BE LAYING OUT ACROSS THE REGION WEDNESDAY AND THIS WOULD BE THE FOCUS OF ACTIVITY. A GENERAL NORTHWEST FLOW ALOFT WILL NOT PROVIDE ANY PROTECTION FROM CONVECTION AND A LATE DAY/EVENING WAVE WILL ONLY INCREASE THE THREAT. STILL HAVE HESITATIONS ON LOCATION AND TIMING OF ANY WAVE THAT FAR OUT. ACTIVITY SHOULD QUIET WEDNESDAY NIGHT WITH THE LOSS OF DAYTIME HEATING AND UPPER LEVEL SUPPORT. REALLY LOOKS LIKE A BROKEN RECORD ON THURSDAY WITH LITTLE TO NO CHANGE IN THE OVERALL PATTERN (ALOFT OR AT THE SURFACE). HUMID AND WARM BOTH WEDNESDAY AND THURSDAY. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... LITTLE CHANGE IN THE FORECAST UNTIL PERHAPS SUNDAY WHEN AN UPPER LEVEL RIDGE MAY BE ABLE TO EJECT STUBBORN FRONTAL BOUNDARY. THIS WILL MEAN A CONTINUATION OF SHOWERS AND STORMS DEPENDENT ON TIMING AND LOCATION OF UPPER LEVEL DISTURBANCES. A STRONGER COLD FRONT IS EXPECTED SOMETIME MONDAY WHICH WILL EVENTUALLY BRING A CHANGE. && .AVIATION /05Z TUESDAY THROUGH SATURDAY/... IFR FOG IS FORECAST AT ALL PORTS THIS MRNG WITH MDL SNDINGS INDICATING A POSITIVE BNDRY LYR HYDROLAPSE WITH A WEAK SFC FLOW AND A CLEARING SKY. THEREAFTER...GENERAL VFR WL RAPIDLY DVLP AFTR DAYBREAK...BUT CONDITION DETERIORATION SHOULD BE EXPECTED TNGT AS AN APCHG SHRTWV SPAWNS SHWRS AND TSTMS. OUTLOOK.../WEDNESDAY THROUGH SATURDAY/... SEVERAL CROSSING DISTURBANCES WILL CAUSE PERIODIC RESTRICTIONS INTO THE WEEKEND. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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