Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPBZ 270526 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 126 AM EDT Thu Jul 27 2017 .SYNOPSIS... Showers and thunderstorms return Thursday and Friday as a cold front and upper level low pressure system move through. Dry and seasonable weather returns this weekend. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... No major changes needed to the overnight forecast. Previous discussion follows... High clouds continue to filter through the area with a long upstream fetch. While the layer below the cirrus is largely bone dry, high clouds show no signs of abating. As such, generally mostly cloudy but still dry conditions are expected. Likewise, with high clouds in place, low temperatures will be up a tad from last night. Fries && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/... Similar to previous forecast, forecast confidence for this period remains low. The one general concept that the deterministic models agree on is that the overall rain shield on Thursday should be somewhat farther to the south. Have increased the gradient in pops from north to south, pushing the line of likely pops farther south and keeping chance pops to the north. However, overall precipitation along the cold front remains somewhat unorganized. Due to concerns about instability, the risk of convective weather on Thursday has been lowered by the Storm Prediction Center down to a marginal area across all counties. Damaging winds remain the primary threat. There should be a bit of a lull in precipitation Thursday night as the surface front plunges south, but precipitation will redevelop as an upper level low drops into the Ohio Valley on Friday and helps to restrengthen low pressure along the front. All locations have likely pops on Friday. Forecast models continue to slow down the departure of precipitation Friday night into Saturday, and have decided to keep pops in the forecast longer through this time period, with morning showers on Saturday only expected in Pittsburgh and locations east. While the severe threat has diminished on Thursday and is not present on Friday, flooding could still be a possible concern. The entire vertical sounding remains quite moist, and warm cloud depths could support plenty of downpours. In addition, flow will be rather weak on Friday, meaning that any storms that do develop will be slow moving in nature. Rainfall could range anywhere from a half inch along Interstate 80 to more than 2 inches in southernmost Tucker County from Thursday morning through Saturday. However, no flood watches have been issued at this time because of the extended time period over which the rain is expected to fall. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... High pressure across the Great Lakes should keep weather dry through the extended forecast, with temperatures remaining seasonable through the period. A front may approach from the northwest by the middle of next week, but the timing remains highly uncertain. && .AVIATION /05Z THURSDAY THROUGH MONDAY/... With dewpoints creeping up around the region and calm winds still in place, the only fog inhibitor this morning will be the presence of high clouds. Latest satellite imagery does show some breaks in the cloud cover. Will continue to carry a fog-free forecast areawide, but cannot rule out a bounce down to MVFR or worse, if a cloud break can persist over a given terminal in the pre-dawn hours. High clouds will continue to push in from decaying upstream convection. As the first in a series of waves approaches from the west today, the energy dissipates, losing organized ascent. As a result, model guidance is continuing it`s trend towards a drier solution. This seems prudent, given the copious dry air present in the lowest 10kft. TAF forecast will reflect a conservative approach to shower and thunderstorm chances this afternoon. Best chances will reside south of KPIT, but activity looks too scattered to mention in any one terminal. Dry air will continue to erode towards the end of the TAF period with perhaps MVFR cigs beginning to show up from KZZV to KMGW. Surface winds will remain light through the period. .OUTLOOK... Restriction chances may continue through Friday and possibly into Saturday as low pressure impacts the Ohio Valley. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.