347 FXUS61 KPBZ 101417 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 917 AM EST Sat Feb 10 2024 .SYNOPSIS... Shower and isolated thunderstorms are expected today with the crossing of a trough over the Great Lakes and cold front. Widespread dry conditions are expected briefly overnight before precipitation chances increase south of I-70 due to remnant shower activity over the Southeast from a passing trough under southwest flow. The next impactful weather will come late Monday into Tuesday as the probability of accumulating snow increases. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Isolated storm activity is expected along I-80 through 1pm this afternoon with a passing shortwave and approaching cold front over the Great Lakes. - Precipitation chances remain elevated through 6pm-8pm before drier air overspreads the region from the northwest. -------------------------------------------------------------- A broken line of showers and isolated thunderstorms are currently situated along Lake Erie this morning with a crossing trough and cold front. If one were to glance at the 12Z PIT and 12Z BUF sounding, pockets of elevated instability (especially near Buffalo, NY where 278J/kg MUCAPE was observed) are noted above 800mb. Hi-Res model guidance suggests thunder chances will remain focused north of Pittsburgh, mostly along I-80, through 1pm with warm, moist conditions at the surface along the frontal boundary. In northwest Ohio, winds have already shifted and dew points have dropped into the low-40s to upper-30s. Drier air will eventually advance into the region and decrease the chances of precipitation between 6pm to 8pm this evening. With low temperatures ranging in the upper-40s low-50s early this morning, there is a chance of record Hi-Min temps being tied or being broken today. This scenario will heavily be depending on how fast the cold front passes late this evening. At the moment, the cold front is expected to be in the vicnity of Pittsburgh,PA around midnight. Therefore, HLG and MGW may have the best chance at breaking or tying their Hi-Min temperature with their prolong period with in the warm sector. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... KEY MESSAGES: - Low-probability rain will linger for northern West Virginia for the morning hours, followed by dry conditions. - Temperatures will remain cooler, but still above average. --------------------------------------------------------------- Some low-probability precipitation may linger in northern West Virginia through the afternoon. Thereafter, the low departs to the east and weak eastern ridging develops in response to a deepening trough over Texas. Temperatures are expected to remain cooler than the day prior behind the cold front, but daytime highs and overnight lows are still expected to remain 10 degrees above average with anomalously warm 850mb temperatures. Throughout Sunday, the aforementioned Texas trough is expected to cut off from upper flow and meander eastward. The strength and track of the cut-off will become important in determining the details of the next impactful system. && .LONG TERM /MONDAY THROUGH FRIDAY/... KEY MESSAGES: - The next potential system will impact the region late Monday into Tuesday, with a range of potential winter weather- related impacts. --------------------------------------------------------------- The cut-off low will develop a coupled surface low over the Mississippi Valley early Monday. As the cut-off draws eastward, it will attempt to re-phase into zonal flow over our area Monday night through Tuesday. In all likelihood, the system will start as rain late Monday. From there, the details get dicey. The strength of the cut-off low will determine various aspects of the surface low behavior. This could play out as a couple scenarios over the forecast area. 1) The upper-low is weaker and phases more rapidly into zonal flow. This would act to keep the surface low track more progressive and farther to the south. Coastal low development would then dominate into Tuesday morning. Because the low track would be farther away, local northerly flow would be weaker. This would lessen the magnitude of cold and dry advection around the backside of the system. An area of frontogenesis is possible, centered over northern West Virginia on the northwest side of the low, though temperatures would likely be too warm to result in snowfall. This solution would result in mostly rain across the area with a lower probability of appreciable snow accumulation. This is reflective of the NBM 10th percentile, where totals amount to zero across the lowlands with a light accumulation for the ridges. 2) The upper low is stronger and slower to re-phase into zonal flow. Though subtle, this would affect surface low behavior and the eventual coastal low development. Under this scenario, ensembles indicate the surface low has a tendency to pull back and collocate under the upper low before the coastal low takes over. This is important. A stronger low across the West Virginia interior could influence three processes. First, stronger north to northeast flow on the northern side of the system would advect cooler and drier Canadian air, capable of wet-bulbing temperatures further. Second, the area of frontogenesis would more likely be in an area that is cold enough to support snowfall. Third, latency time of favorable lift increases as the cut-off is slower to incorporate into the upper flow. These factors could lean towards snowfall amounts toward the higher end of the distribution. Even then, there is still uncertainty with the exact track that the cut-off low may take, adding uncertainty to the area that may see the highest snowfall totals. This scenario is more reflective in the NBM 90th percentile, which shows a sizable tract of 6"+ of snow across western Pennsylvania and the northern West Virginia panhandle. With the spread as large as it is between these two scenarios and still a great deal of uncertainty in track, the current forecast is reflective of some "middle-ground". Though not necessarily the "most-likely" scenario, will opt to continue to trend toward the more likely solution as more information becomes available in subsequent updates. The rest of the week is expected to remain comparatively cooler and drier as the region sits north of a prominent southeast jet, shunting the main storm track south accordingly. Nonetheless, a few shortwaves in quasi-zonal flow will allow for intermittent, low-QPF, rain and snow chances. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... MVFR cigs will quickly overspread the region before dawn and remain over the area through the rest of the morning. Rain showers will begin to move in from the west later this morning and press through the area during the afternoon hours. Rainfall looks to be light and should remain non-restrictive. There is a low chance for a thunderstorm this afternoon. If convection does develop, it could bring vis restrictions, but the probability that a storm would hit a port is very low. Surface wind gusts will strengthen this morning. Gusts of 20 to 25 mph are possible throughout the day. An improvement back to VFR cigs is anticipated during the afternoon, except at FKL and DUJ where MVFR cigs may linger. However, a rain shower could bring a brief restriction. .Outlook... Improvements to VFR are expected for most terminals late Saturday followed by a possible dip in cigs again Saturday night. Widespread VFR is likely once again on Sunday before restrictions return Monday into Tuesday as the next weather system approaches from the south. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Hefferan NEAR TERM...Hefferan SHORT TERM...Milcarek LONG TERM...Milcarek AVIATION...22