Area Forecast Discussion
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234 FXUS61 KPBZ 231851 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 251 PM EDT Mon Oct 23 2017 .SYNOPSIS...
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Low pressure will maintain chances for showers and cool temperatures through mid week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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A potent closed low in the central CONUS will maintain deep, moist sely flow across the Great Lakes through tonight. Breezy conditions in the ridges can be expected to continue as the terrain penetrates into the strong flow above the shallow sfc inversion. Considerable moderate rain will increase this afternoon and evening for much of the region as moisture flux strengthens ahead of the upper low. Although we are outlooked in a marginal risk of both severe and excessive rainfall, any threat appears quite minimal lacking instability. The ground and rivers both can tolerate considerable rain given the dry antecedent conditions. A dry slot will encroach late tonight, spelling an ewd shift and end to the moderate rain showers.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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A closed upper low will linger in the Great Lakes region Tue and Wed, with likelihood of precipitation being moderated by dry air being wrapped into the upper circulation. After a showery day on Tue, the system`s dry slot will shift the brunt of precipitation ewd, and any remaining showers will be driven by the cold pool aloft as the trough meanders ewd. There is a non-zero possibility of snow showers in the ridges Wed night as cold air invades, but precipitation may be ending by the time the air cools sufficiently for accumulation. Owing to the presence of the strong trough, temperature will be seasonal to below average for the time of year, with maxima in the low-mid 50s common by Wed.
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&& .LONG TERM /THURSDAY THROUGH MONDAY/...
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A quasi-zonal flow pattern will take shape Thu and Fri in the wake of the early-week trough. However, a deep upper trough will be carved out in the central CONUS by Fri, and a cold front will surge ewd, approaching the region by Fri evening. Thu and Fri seem quite likely to be dry as moisture and lift will be lacking. However, the weekend likely will be wet and colder than recent days, as the deep trough is slow to depart.
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&& .AVIATION /19Z MONDAY THROUGH SATURDAY/... VFR conditions will drop to MVFR during the afternoon and evening hours as a cold front moves through the region. While wind gusts were expected to have developed by 18Z, since they have not, decided to start the TAFs with a period of low level wind shear as both speed and directional shear are present. Along the cold front itself, isolated IFR conditions will be possible along with gusts up to 30 kt. The bulk of the rain should have moved east by the early morning hours on Tuesday, and low ceilings will remain. Some gradual improvement back to VFR should happen by the afternoon. .Outlook... Periodic restrictions will continue into early Thursday with the region under upper troughing. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ Kramar

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