Area Forecast Discussion
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000 FXUS61 KPBZ 200839 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 339 AM EST Mon Feb 20 2017 .SYNOPSIS... Dry and warm conditions will continue until a frontal system crosses the region Tuesday night. Well above normal temperatures are expected through the end of the work week. && .NEAR TERM /THROUGH TONIGHT/... Stratus coverage remains somewhat stagnant in the ridges and generally along and south of I-68 early this morning. While this seems unlikely to change for the rest of the early morning hours due to nearly nil advection, rational cooling across Ohio and areas along the I-70 corridor in PA have allowed for the development of fog. This is generally south of a dewpoint discontinuity that was quite noticeable on radar as it pushed through Pittsburgh late last evening. In the more moist area south of this boundary, some fog will be possible. To the north, clear skies will rule the roost. Dense fog advisories have been issued for portions of Ohio where the most dense patches of fog seem to be occurring based upon observations and fog product satellite imagery. Fog and stratus should mix out fairly efficiently on Monday. With that in mind, 850 mb temperatures seem poised to run up a degree or two relative to Sunday. With a bit higher dewpoints, this will have more difficulty being translated to the ground, so in areas that were clear on Sunday, highs will be relatively similar on Monday. In areas that had stratus on Sunday, highs will likely be half a dozen degrees warmer on Monday. Fries && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... The latest model runs continue to slow the progression of a weak front, as it attempts to break down the sharp ridge over the eastern CONUS. With the slower progression, likely PoPs are not introduced until later in the afternoon/evening, which leaves more time for daytime heating in warm advection/mixing. Thus, highs were bumped up a few degrees despite increasing cloud cover. The slower passage of the front will leave the chance for rain in the southern zones through Wednesday morning but this boundary will do little to change the continued unseasonable warmth as 850hpa temperatures approach +10C once again. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Broad upper ridging will continue to support fast moving waves and warm temperatures through the end of the week, followed by a brief return to seasonal values with the passage of a more amplified shortwave and associated low pressure on Saturday. Before this system approaches, a weak wave passing north over the northern Great Lakes may bring a slight cool down and low chance PoPs on Thursday, before a the warm front with the intensifying low lifts back over the region. Strong warm and moist advection in advance of this system will support values nearly 30 degrees above normal on Friday, hampered only by any shower activity that occurs. Sharp cold front will pass Saturday morning, based on consensus of model guidance. Expect a non-diurnal trend in temperatures through Saturday, but high pressure building over the region will limit snow shower activity. Likely PoPs and a chance of thunder were maintained in the forecast with the Friday night/Saturday front passage. && .AVIATION /09Z MONDAY THROUGH FRIDAY/... VFR conditions for most airports PIT northward are expected through the morning under building high pressure. Higher dew points are in place S of I 70 where cloud cover prevented full mixing during the day. These areas should see IFR/local LIFR fog and possible stratus overnight through early Monday morning. The fog should burn off as mixing begins, with VFR conditions expected for all locations the rest of the day under the high. .OUTLOOK... Restrictions are likely with a Tuesday trough and a late Friday cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...Dense Fog Advisory until 10 AM EST this morning for OHZ039-048- 057>059-068-069. PA...None. WV...None. && $$

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