Area Forecast Discussion
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000 FXUS61 KPBZ 280206 AAC AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 906 PM EST Mon Feb 27 2017 .SYNOPSIS... A series of disturbances will keep periodic rain in the forecast through mid week until the passage of a cold front returns wintry weather for the last half of the week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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905pm update...Have removed all PoPs and put in sprinkles across the north, right along the warm front. South of the boundary, surface dewpoints have been slowly rising which is allowing for fog to form in some locations. Have included the mention of fog overnight, especially in local valleys. Temperatures have been adjusted with a blend of data. Previous discussion... The system looks to clear the eastern portions of the area this evening. Layer RH values start to fall off late in the evening from S to N, likely revealing some clearing before clouds look to start to increase from the west ahead of the next system. Temperature expectations overnight will likely be modulated by the exact interval and longevity of clearing with the low temperature forecast gradated from cooler east and warmer south as a result. Fries
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... Models continue to depict a series of shortwaves to cross the region Tuesday. These disturbances with the combination of strengthening low level SW flow will support periodic showers through Tuesday night. Thunderstorm chances increase gradually throughout the day as elevated instability and shear increase. By Wednesday, the western trough is progged to approach the Great Lakes region as an associated surface low tracks from the Midwest into Southern Ontario. Speed and directional shear will continue to increase as the cold front progresses southeast but models differ in the amount of instability progged to develop. Preceding rainfall and cloud debris may inhibit greater instability development. Hence, the severe weather coverage remains uncertain at this time and will depend on how much CAPE is present. Though uncertain in the occurrence of damaging winds on Wednesday, the possible threat will continue to be mentioned in the hazardous weather outlook due to substantial shear and high confidence in convection development. Post-frontal cold northwest flow will lead to lake and terrain induced snow showers on Thursday. Temperatures are expected to be 20 to 25 degrees above average Tue and Wed, returning to near or below seasonal levels Thursday. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Broad upper troughing is expected to continue through the late week, with a reinforcing crossing shortwave/surface low with some snow Thursday night and Friday. Some snow may accumulate across the higher terrain areas. General zonal flow is then progged by the weekend as the trough exits, with mainly dry conditions and moderating temperatures. By Monday, temperatures should rise to nearly 15 degrees above the average. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/...
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General VFR cig forecast through Tuesday morning. There may be some MVFR cigs that pass through FKL and DUJ this evening, but those too will dissipate. Will need to include the mention of fog, particularly at those ports that rest near valleys and rivers. Low level moisture is slowly increasing south of the warm front and with temps doing very little today, it will be easy for ambient temps to reach the dewpoint. Fog will dissipate after dawn. Restrictions return Tuesday afternoon with rain and low clouds. .OUTLOOK... Restrictions are likely Tuesday as precip develops with another shortwave in strengthening wsw flow. More restrictions and wind problems can be expected with, and in the wake of a Wednesday cold front.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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