Area Forecast Discussion
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798 FXUS61 KPBZ 271912 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 212 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 /THROUGH TONIGHT/... Light rain is just starting to overcome the dry air below 800 mb that was present on this morning`s 12z KPBZ sounding. The first reports of rain have started to trickle in over the past half of an hour around Zanesville, roughly in line with both large scale and hi-res model timing. As the wave generating the warm advection light rain over the area slides ENEward over the afternoon, this rainfall will likely develop farther ENE across the area. Likely PoPs have been maintained for this activity, however saturation is over a fairly limited time interval, and lift is somewhat unimpressive, so QPF remains light. 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 && .SHORT TERM /TUESDAY 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 /18Z MONDAY THROUGH SATURDAY/... Restrictions of the MVFR variety will be likely shifting ENE from ZZV toward PIT through the afternoon today as light rain develops across the region ahead of a weak system. While rainfall may not make it all the way to FKL, a period of MVFR cigs may this evening for a time. Skies should start to scatter out beyond the evening for a period at most sites with a window of VFR conditions before the next system on Tuesday. .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. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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