Area Forecast Discussion
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988 FXUS61 KPBZ 232118 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 518 PM EDT Tue May 23 2017 .SYNOPSIS... Unsettled weather will return for the remainder of the week as an upper-level disturbance moves slowly across the Ohio Valley. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/...
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An approaching shortwave will result in light and scaterred shower devlopment early this evening south of I-70...with coverage gradually spreading further north as the night progresses and the very dry lower levels begin to saturate. Scaterred precipitation remains a possibility through Wednesday as a deep upper trough continues east towards the forecast area...becoming more widespread by early Wednesday evening as moisture increase further and the upper trough axis moves moves over the ohio river valley providing more favorable dynamics. Temperature on Wed will see little difference to those today, as insolation may be limited by clouds but cloud cover overnight will limit radiational cooling effects and provide a warmer initial state.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... A strong upper-level low pressure system will meander from the Central Plains into the Ohio Valley late in the week, leading to a persistent active weather pattern through the end of the week. Although air temperature will decrease slightly into the upper 60s owing to cloud cover, cold air aloft associated with this low is expected to provide a modest increase in instability Thu and Fri, which will increase the chances for more-vigorous convection, especially as the low-level wind flow veers to more of a wly component. && .LONG TERM /SATURDAY THROUGH TUESDAY/... The slow-moving upper low will advance newd by Friday night, and an upper ridge will take hold briefly. Quiescent conditions will be relatively short-lived as the mid-level ridge axis progresses quickly ewd. The net effect will be a return to deep swly flow aloft for the weekend. This will bring Gulf moisture toward the area again, resulting in increasing temperature and humidity and increasing convective chances at least through Memorial Day. && .AVIATION /21Z TUESDAY THROUGH SUNDAY/... VFR conditions are expected through the evening as only high clouds build into the area. The coastal low pressure system will begin to spread light rain into the area tonight, but no visibility restrictions are expected. Ceilings may begin to fall to near MVFR near daybreak Wednesday. Wind will remain light and from the east-southeast through the period. .Outlook... Restrictions are likely late Wed thru Thu and are possible Thu night thru Sat with crossing low pressure. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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