Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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808 FXUS61 KPBZ 070432 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1232 AM EDT Fri Jun 7 2024 .SYNOPSIS... Probability of rain showers will be elevated on Friday north of Pittsburgh with passing shortwave. Below average temperatures are also expected into late Saturday. && .NEAR TERM /THROUGH FRIDAY/... KEY MESSAGES: - Pockets of river valley fog will continue to develop early this morning east of Pittsburgh. - Probability of rain shower activity increases after day break north of Pittsburgh with a passing shortwave. - Areas north of I-80 may observe a few thunderstorms; small hail may develop. - Confidence is high that rainfall total amounts through Friday evening will be less than 0.25 inches. -------------------------------------------------------------- A passing surface trough is created enough lift early this morning to create a few stray showers across the region. Probability of precipitation decreases below 10 percent just before 3am. With noted remnant moisture, light winds, and some breaks in the clouds, river valley fog is noted northeast of Pittsburgh on Nighttime Microphysics GOES-16 satellite. However, confidence is high that fog will not be an issue during the early morning commute with passing clouds from the northeast with a new shortwave. Rain showers probabilities increase after 10am north of Pittsburgh with a passing shortwave and will likely continue into the late evening. Hi-Res model soundings suggest pockets of 50J/kg to 150J/kg low-level instability during peak heating. Therefore, a few updrafts may lead to thunderstorm activity. With a low freezing level (7kft to 8kft) and storm tops projected near 10kft to 11kft, a few cell may produce small hail. With rainfall activity being sporadic, low PWATs, and the loss of a well- defined warm cloud layer, rainfall totals will be range between a trace to 0.25 inches across the region; higher amounts mainly focused near I-80. High temperatures will range from mid-70s to mid-60s Friday afternoon. The probability of higher temperatures will likely be south of I-70, where clouds and precipitation will be heavily absent for a large portion of the day. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... KEY MESSAGES: - Persistent upper trough maintains an unsettled pattern - Cooler temperatures expected ------------------------------------------------------------------- An upper low will drift across southeastern Canada and the Great Lakes region Friday through Saturday night. Individual shortwaves rotating around the low will keep an unsettled pattern across the Upper Ohio Valley region through the remainder of the period. A diurnal trend to the cloud cover is expected, with low convective temperatures in place and cool air aloft. One of these shortwaves is expected to cross the Upper Ohio Valley region on Friday, with isolated to scattered showers. Another is expected for Saturday, though the best upper support for any showers is expected to be mainly north of PGH. A stronger shortwave rotating around the low is expected to cross the region Saturday night, with scattered showers across much of the area. Temperatures are generally expected to average around 5 degrees below seasonable levels through the period. && .LONG TERM /SUNDAY THROUGH THURSDAY/... KEY MESSAGES: - Unsettled pattern through mid week under a series of upper troughs - Cool temperatures to start should warm next week ------------------------------------------------------------------- Shortwave troughs rotating around the upper low, mentioned in the short term section of the discussion, will maintain scattered showers on Sunday and Monday, though much of the time in any one location will be dry. Mainly dry weather is expected on Tuesday as the upper low exits the New England coast, and ridging briefly builds in. A shortwave trough is expected to advance eastward from the Plains region Tuesday night, crossing the Upper Ohio Valley region on Wednesday. Scattered showers are expected with the approach and passage of the trough. Temperatures should start out a few degrees below average Sunday and Monday, before returning to near, or above average readings by mid week. && .AVIATION /04Z FRIDAY THROUGH TUESDAY/... Some widely scattered showers forming off of remnant outflow boundaries, which have caused brief shifts in wind direction, will wane after sunset and VFR conditions prevail overnight with light wind 5 knots or less. Wind will increase with mixing on Friday morning out of the west with gusts to 15-20 knots. Diurnal cumulus will develop beneath a building subsidence inversion as high pressure noses in from the southwest. An upper wave will pass by the northern part of our area bringing a chance (30-40%) of scattered showers for the afternoon. There is also a low confidence chance (~30%) of a brief period of MVFR CIGs early Friday morning for FKL but conditions will otherwise remain VFR through the TAF period. .Outlook... Periodic restrictions and scattered showers are then expected through Sunday as a slow moving upper low persists across the Great Lakes region. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Hefferan NEAR TERM...Hefferan SHORT TERM...WM/88 LONG TERM...WM/88 AVIATION...Cermak/MLB