Area Forecast Discussion
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233 FXUS61 KPBZ 211923 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 223 PM EST Sun Jan 21 2018 .SYNOPSIS...
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Warm temperatures and patchy light rain will linger through Monday. A cold front brings more organized rainfall Monday night. Seasonable temperatures and snow showers return by late Tuesday.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Ongoing warm advection along a slow-moving warm front is keeping low clouds and locally dense fog in the I-80 area. Conditions here should improve over the next few hours. To the south, cloudy skies linger with little to no precipitation currently. Deepening isentropic lift near the lingering frontal zone should allow for the development of light rain as depicted on hi-res models, with the best coverage north of Pittsburgh. Have likely PoPs in this area, with the expectation of light QPF during the overnight period. Ongoing snow melt and warm advection will promote the development of at least light fog once again over much of the area, and have added that mention to the forecast. A nearly saturated boundary layer will not allow much of a temperature drop-off with most minimums in the 40s.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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The models continue to handle the approaching storm system with decent agreement, although the timing of Monday afternoon/evening rain arrival may be a touch later. The warm frontal zones continues to lift out of the region during Monday morning, with light rain pushing north. Precipitation coverage reaches a minimum by midday as the warm sector entrenches itself over the region. The stacked low still tracks across the Mississippi Valley and into the Great Lakes by Tuesday morning. This drags a cold front across the region on Monday night. Given the consistent model handling, upped PoPs to near 100 percent. The relatively thin precipitation shield and progressive nature of the front means that QPF is still expected to top out around a half inch through 12Z Tuesday. Thus, outside of possible isolated issues due to lingering river ice, flooding issues will be held to a minimum. A more seasonable air mass will rush in behind the boundary on Tuesday, with falling temperatures during the afternoon. Rain showers will change to snow showers during the afternoon and evening, with continued decent coverage provided by support from the passing upper trough. Best coverage will be north of Pittsburgh , but non-favorable trajectories and an icy Lake Erie will negate any lake enhancement. Still, around an inch is possible near and north of I-80 and perhaps on the higher southeastern ridges, with little or no accumulation elsewhere.
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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A few snow showers will linger into Wednesday, but building high pressure will shut off most of the precipitation by Wednesday evening. Dry weather is forecast for Thursday and Friday, with temperature moderation back above normal by the end of the week as the upper ridge crosses. Another trough emerges from the Plains next weekend with the next chance of rainfall.
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&& .AVIATION /19Z SUNDAY THROUGH FRIDAY/...
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While some improvement has been observed at the TAF sites south of KFKL and KDUJ, expect this to be short lived with prevailing IFR and low MVFR conditions in stratus across all terminals again tonight. A little uncertain to the extent of fog, but opted to take a persistence type forecast, albeit slightly more optimistic, with scattered showers/drizzle anticipated. Deep low level moisture will finally lift northward tomorrow with the warm front, which should return VFR to all sites by late afternoon. A WSW wind will persist through the period, and generally stay below 10kts .OUTLOOK... Restriction potential continues Monday night with the passage of a cold front.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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