Area Forecast Discussion
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958 FXUS61 KPBZ 241809 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 209 PM EDT TUE MAY 24 2016 .SYNOPSIS... Mostly dry weather is expected through Wednesday. A weak disturbance will provide a chance of rain starting Wednesday night. A slow warming trend will continue through Friday. && .NEAR TERM /THROUGH WEDNESDAY/... A 500 mb ridge will keep the forecast area dry over the next 24 hours. Overall moisture in the column is fairly limited, but still enough for some diurnal cumulus this afternoon. These will collapse towards sunset. Mostly clear skies are forecast overnight, although a bit of cirrus may spill over the ridge late. Low temperatures will be seasonable, but still a few degrees above climatology. The upper ridge shifts east on Wednesday, and increasing southwest flow will start the process of increasing dewpoints. More diurnal cumulus are expected. Although low-level instability will start to increase, a mid-level cap will keep convection at bay for much of the area. Southeast Ohio may get just moist enough to break the cap for a few isolated showers and storms after 18Z, and have slight chance PoPs here. With rising 500 mb heights and 850 mb temperatures, we expect afternoon highs to be a few degrees warmer than today. CL && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... A weak shortwave trough in the midst of an unstable atmosphere is progged to slowly pass on Thursday. Hence, showers and thunderstorms are expected to develop in the afternoon and evening. Unstable conditions will continue into Friday as the broad ridge of high pressure strengthens and terrain driven diurnal thunderstorms occur. Very warm and humid conditions are expected through the period via southwest flow with temperatures forecast to be at least 10 degrees above average. Have used a blend of GFS, NAM, and WPC guidance for temperatures as a broad and anomalously strong ridge pattern holds across the region. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... The ensemble members continue to be in good agreement that the aforementioned ridge enhances. Above average temperatures with humid conditions are expected. Saturday appears to be the warmest day of the period as the ridge axis is progged to be very near or directly over the forecast area while mid-level heights have reached their maxima. The overall broad ridge of anomalously high pressure over the Eastern US remains certain through the period and thus near WPC values for temperatures were used. Diurnal convection can be expected each day and so chance pops have been maintained. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... VFR flight conditions will continue into Wednesday afternoon underneath high pressure. Milder overnight temperatures and a dry air mass will keep fog formation very limited to perhaps a few of the deeper valleys or cooler water sources. .OUTLOOK /WEDNESDAY THROUGH SATURDAY/... The next chance for restrictions will come with the advance and passage of a disturbance late Wednesday and Thursday. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.