Area Forecast Discussion
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000 FXUS61 KPBZ 201945 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 245 PM EST Sat Jan 20 2018 .SYNOPSIS... High pressure will maintain dry and warmer weather through today. Light rain chances return with the new week. && .NEAR TERM /THROUGH TONIGHT/...
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Plenty of sunshine remains in place across the region, and temperatures in the 40s are allowing for some snow and ice melt. Clouds are starting to advance across the middle Ohio Valley, where low level moisture/surface dewpoints show an increase. Based on satellite trends, have slowed down the cloud increase for our area even further from this morning, bringing in the bulk of them after sunset. Have kept the chances of light rain or drizzle overnight with the development of weak isentropic lift in the moisture-bearing layer. Still some question as to whether temperatures can drop enough to allow for freezing rain/drizzle for a period across the far northeast CWA late tonight. Model soundings indicate that the surface wet bulb values should remain at or above freezing for the most part, and with the column remaining stirred, do not foresee a big temperature dropoff this evening despite the lingering snowpack. Will leave out freezing mention for now, but will alert following shift to monitor trends.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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Chances of light rain or drizzle will remain for Sunday and Sunday night as southwest flow continues to bring slow lift and moisture increase. Temperatures will tick up a degree or two as compared to yesterday. Snow melt will continue, especially with dewpoints climbing above 32 degrees, helping to keep any non-ice jam flooding concerns at bay for the upcoming weather system. Warm advection continues to ramp up Monday as a stacked low pressure system crosses the Mississippi Valley. Temperatures will reach at least the 50 degree mark CWA-wide, with some 60+ plus readings south of Pittsburgh. This will finish off the snow pack. A relative minimum of light rain activity will be seen during the day as the warm sector strengthens. The low will cross the Great Lakes Monday night and early Tuesday, pushing a well-advertised cold front across the region. PoPs were upped further into the categorical range given good model consensus. The progressive nature of the system plus the relatively narrow moisture plume still point to relatively subdued QPF of around a half inch with this system. Again, this will limit general flooding concerns.
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&& .LONG TERM /TUESDAY THROUGH SATURDAY/...
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More seasonable temperatures will flow into the region behind the front, with rain showers changing over to snow showers Tuesday afternoon and evening. Any accumulation is expected to be minor at this distance. Showers taper off by Wednesday night, and high pressure provides dry weather Thursday and Friday, with another warming trend towards above normal temperatures. Rain chances may return by the end of the extended as a trough emerges from the Plains.
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&& .AVIATION /19Z SATURDAY THROUGH THURSDAY/...
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VFR will continue through much of the afternoon before MVFR and IFR stratus develops in an increasing warm and moist regime. Expect these conditions to then prevail through the night with some light rain anticipated along a lifting warm front. Deep moisture will remain present through the rest of the period but opted to lift cloud deck after sunrise, despite pessimistic model trends. WSW wind will remain gusty to 20-25kts through the evening, with some weakening expected as warm advection strengthens inversion aloft...capping momentum transfer. .OUTLOOK... Restriction potential continues for the first half of the week with the approach and passage of a frontal system.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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