Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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081 FXUS61 KBUF 060730 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 330 AM EDT Thu Jun 6 2024 .SYNOPSIS... A slow moving cold front will press through the region with showers likely today, and thunderstorms possible this afternoon. Today will be the final day of this stretch of summery-like weather as temperatures are slated to average below normal from Friday through Monday of next week. The cooler weather will be accompanied by fairly frequent shower activity. && .NEAR TERM /THROUGH TONIGHT/... Surface analysis shows a deep low pressure system over south-central Canada this morning. There are two cold fronts that extend southward from this low pressure system, the westward one extends south across Michigan while the eastern cold front extends south across Lake Erie and Ohio this morning. Regional radar shows showers ahead of these two cold fronts, and locally, these showers are across western and north central NY this morning. The airmass is saturated and any showers will produce heavy downpours. The western Southern Tier continues to get the bulk of the heavier showers with rain gauges across Chautauqua county reporting 0.75-1.25 inches overnight. It will be the last day of our summery stretch of weather as a deep low pressure system the Great Lakes region today. The forecast area remains on the warm side of an approaching cold front this morning. Muggy conditions persist with dewpoints in the 60s across the region. Lightning has dropped off overnight, however an area of 500- 1000 J/kg of MLCAPE exists immediately upstream and may move into western NY this morning. This will keep a low chance of thunderstorms through mid-morning. The cold front will enter western NY between 6-8am this morning. There will be a wind shift from south to west-southwest with an uptick in winds behind the front. Most showers will end from west to east with partial clearing across western NY this morning. Post-frontal conditions are favorable for additional cumulus and showers to develop along a convergence zone from the Niagara Frontier to Rochester, mainly north of the City of Buffalo into this afternoon. As dry conditions move in behind the front, daytime heating and dewpoints in the 60s will be ahead of the front. Mid-level winds will increase ahead of an approaching trough and conditions will become favorable for thunderstorm development from the Finger Lakes region to north central NY this afternoon. There is a Marginal Risk of Severe thunderstorms and isolated severe thunderstorms are possible within this corridor. The increase in winds will also cause southwest winds to gust up to 35 mph east of Lake Erie this afternoon. Elsewhere, gusty winds around 25-30 mph are possible. Highs will reach the mid to upper 70s across the region today. The aforementioned deep trough will move across the eastern Great Lakes region tonight. Cold air advection will spread eastward and the switch to cooler weather will arrive for Friday. Moist, cyclonic flow will also move into the region and showers will increase in coverage by Friday morning. Lows will reach the 50s. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... A very unsettled pattern will continue Friday through the weekend as a mid level closed low moves very slowly from near Georgian Bay Friday morning eastward across southern Quebec over the weekend. A multitude of shortwaves will round the base of the closed low and bring periods of enhanced ascent and deeper moisture to our region, producing frequent rain chances. These smaller scale shortwaves become more difficult to place in time and space beyond a few days, with the finer details of the forecast becoming more uncertain beyond Saturday. Friday, the base of the mid level low will move across the eastern Great Lakes, bringing with it a period of deep moisture and ascent. Cool temperatures aloft will support steepening lapse rates with modest diurnal heating. The coverage of showers should still be rather sparse early in the morning, but expect a quick expansion of shower coverage and intensity by late morning into the afternoon as the deeper moisture and forcing arrive and interact with steepening lapse rates. Instability will be weak, but still may support some isolated thunder in the afternoon and evening. Stable lake shadows will keep shower coverage lower east and northeast of Lake Erie and Lake Ontario, but the synoptic forcing may be strong enough to overcome the lake shadows to some extent. Friday night, showers will continue as the trough moves slowly east. Temperatures aloft become cool enough to support lake enhanced showers east of the lakes, especially east of Lake Ontario overnight as 850MB temps fall to around +5C or so. This is a rarity in June, but the cool temperatures aloft combined with well above normal lake temperatures will bring our first lake effect rain showers of the 2024-2025 season. Saturday through Sunday, the closed low and trough axis will continue to move slowly east. Cyclonic westerly flow will continue across the Great Lakes, along with a series of difficult to time mid level shortwaves. The 00Z model guidance suggests the most notable of these waves will move across the eastern Great Lakes Saturday night, bringing a greater chance of more organized rainfall. Otherwise, weak diurnal instability, lake breeze boundaries, and general weak large scale forcing will continue to support scattered to numerous showers and possibly a few isolated thunderstorms Saturday through Sunday. Temperatures will run below average through the period with the persistent trough and cool air aloft in place. Highs Friday through Sunday will generally be in the 60s. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... The same general longwave pattern will remain in place across North America through early next week, with an expansive ridge in the west and a trough in the east. The trough and associated forcing, deeper moisture, and cool air aloft will continue to support showers and cool temperatures through at least Monday. By Tuesday, forecast model guidance continues to show the trough axis making some eastward progress to along or just off the east coast. There may still be a few spotty showers, especially in the afternoon across higher terrain inland from the lakes, but the coverage of showers should be much lower than previous days. Tuesday night and Wednesday height rises will spread across the Ohio Valley and eastern Great Lakes ahead of another trough digging into the upper Great Lakes. This will bring a brief interlude of dry weather, but shower chances may start to increase again as early as Wednesday afternoon with the approach of the upstream trough. Temperatures will warm through midweek as the pool of cool air aloft exits. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... VFR conditions will become MVFR/IFR by this morning as showers move across western and north central NY overnight. While the threat for TS has reduced significantly as showers have moved into a more stable airmass, the threat continues as a cold front approaches the region. The cold front will slowly cross the region today with winds becoming westerly. Overall, flight conditions will improve from west to east across western NY through this afternoon. Additional cumulus and showers are possible from KIAG/KBUF To KROC along a convergence zone this afternoon. This may produce a brief period of MVFR conditions. Southwest winds will increase east of Lake Erie with gusts up to 30kts from KBUF To KGVQ this afternoon. Showers will continue east of Lake Ontario through this afternoon. The threat for thunderstorms increases east of Lake Ontario this afternoon which may result in heavy downpours and gusty winds at KART. Flight conditions will improve to VFR tonight. Outlook... Friday through Monday...VFR/MVFR with mainly daytime showers likely with possible thunderstorms. && .MARINE... A cold front will cross the Lower Great Lakes this morning. Showers will continue with the threat for thunderstorms increasing across the eastern half of Lake Ontario this afternoon. SW to WSW winds will freshen on both Lakes today through Friday in the wake of the cold frontal passage with choppy waters developing. Conditions may possibly near Small Craft Advisory criteria for a couple of brief periods, especially across eastern Lake Erie. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...HSK/RSH NEAR TERM...HSK SHORT TERM...Hitchcock LONG TERM...Hitchcock AVIATION...HSK MARINE...Apffel/HSK/JM/TMA