Area Forecast Discussion
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124 FXUS61 KPBZ 191955 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 255 PM EST Thu Jan 19 2017 .SYNOPSIS...
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Rain will return to the region late tonight and Friday as the next upper level system moves through. The mild pattern continues through the weekend.
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&& .NEAR TERM /THROUGH FRIDAY/...
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Although some partial clearing is working its way into the region from the southeast, think that most locations will remain partly to mostly cloudy before next round of clouds moves in from the southwest as low pressure approaches. All models continue to slow down the arrival of precipitation, with HRRR/RAP even slower than the synoptic models. Went with timing closer to the synoptic models, which keeps any mention of rain out of the evening forecast and doesn`t bring rain to Pittsburgh until sunrise. Although temperatures will initially fall this evening, temps should slowly begin to rise after midnight and continue to rise through Friday. This should keep the chance for snow minimal. Warm advection should allow highs on Friday to range anywhere from the mid 40s along the I-80 corridor to almost 60 degrees across southern counties.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
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Although different models show isolated showers through this period, have decided to go with a dry forecast Friday night and Saturday, and chance pops Saturday night since there should not be much to provide any sort of organized lift. This should be the warmest stretch of the forecast, with lows only dropping into the 40s and many locations reaching the 60s on Saturday.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
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A strong upper low will develop over the Southern Plains Sunday and track eastward into early Monday, before turning toward the northeast Monday night and Tuesday. While the GFS and ECMWF keep the surface low moving along the Atlantic coastline, the NAM keeps the surface low as far west as Kentucky, and have not used the NAM during the early part of the extended forecast. The GFS and ECMWF are trending farther east with the track of the system, and while they are in good agreement, this track may result in the widespread precipitation shield also being farther to the east. Nevertheless, have still kept likely pops in the forecast for now from Sunday through Monday night. After a brief break in precipitation Tuesday, GFS and ECMWF are in good agreement showing low pressure moving across the Great Lakes Wednesday and Thursday, and have gone with chance pops. Although temperatures will be lower with multiple storm systems, the forecast remains well above normal warmth.
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&& .AVIATION /20Z THURSDAY THROUGH TUESDAY/... IFR cigs will persist as low level moisture remains trapped under building high pressure. A brief break is possible overnight shortly before the next disturbance returns rain and IFR/LIFR cigs. .OUTLOOK... Restrictions are likely with low pressure Friday, and again on Sunday. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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