Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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668 FXUS61 KBUF 072039 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 439 PM EDT Sun Jul 7 2024 .SYNOPSIS... High pressure centered over Lake Erie will slowly drift east and provide us with fair dry weather through Monday night. A slow moving cold front will then sag across and stall over our region late Tuesday and Wednesday. Remnants from Beryl will circulate up across the forecast area during this period to help set the stage for the potential of some areas to receive multiple inches of rain. && .NEAR TERM /THROUGH MONDAY NIGHT/... Another pleasant...star filled night can be expected tonight with temperatures settling into the upper 50s to lower 60s. As was the case this morning...the clear skies and light winds will encourage fog to form in the Southern Tier valleys. High pressure wedged from New England to West Virginia will then guarantee another sunny day to start the new work week. Temperatures aloft will nudge upwards into the mid teens C...so that will allow Mondays max temperatures to climb WELL into the 80s to near 90. While fair dry weather will persist Monday night...it will be a notably warmer night with lows ranging from the mid 60s across the Southern Tier and North country to nearly 70 degrees elsewhere. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... ...Significant Rains from Beryl Possible Wednesday... A warm and unsettled, though not overly active day expected Tuesday as weak troughing remains upstream over the central Great Lakes. With weak moisture advection and leading shortwave energy moving into the region, expect some widely scattered convection to develop in the afternoon mainly focused on lake breeze boundaries during peak heating hours. While there will likely be more mid and high cloud cover around, expect daytime temperatures well into the mid and upper 80s, even a few low 90s across the typical warm spots in the Genesee Valley and Finger Lakes regions. While convection will likely wind down with the setting sun Tuesday evening, rain chances will increase later in the night ahead of the next complex system emerging to our west, though the vast majority of the night is expected to be dry. Overnight lows will range from the mid 60s across the hilltops to the low 70s across the Lake Plains. A complex rainfall forecast is shaping up for the midweek timeframe. Weak, positively tilted longwave troughing initially across the Upper Midwest and Great Lakes region Tuesday morning will slowly translate eastward and de-amplify New England Tuesday night. Broad upper level troughing will remain over the western Great Lakes as reinforcing shortwave energy slides southeast out of Manitoba and into the Dakotas. It is this shortwave energy that is expected to interact with what will then be post-TC Beryl through the course of the day Wednesday, causing a sharp mid-level trough and attendant sfc cyclone to emerge over the Upper Midwest/western Great Lakes, which will then slowly trudge northeast. A belt of warm tropical moisture advection with PWATs surging to 2-2.5" will extend northeast out ahead of the system and move into the eastern Great Lakes as it does so. The main slug of heavy rain looks to come sometime between Wednesday afternoon and late evening as this deep tropical moisture overlaps sharp mid-level convergence along an 850H warm front under diffluent flow aloft. There will also likely be embedded thunderstorms that will locally enhance rainfall rates and amounts, though severe potential looks to be lower than the rainfall threat at this time. The bands of heaviest precip should begin to shift east out of western NY and into the North Country late Wednesday night. It should be stated here that with the large amount of dynamics in play, how exactly these features will interact will have a large impact on the sensible weather and thus the deterministic forecast, especially in regards to expected rainfall amounts and timing. The timing of the reinforcing shortwave trough and the track of Beryl`s remnants will be crucial to where the axis of heaviest QPF sets up over our region, and there remains ample uncertainty in these details at this range. However, given the overall synoptic setup and PWATs climbing to near the daily maximum for the time of year, large swaths of rainfall totals of 1.5-2" are very well possible, with locally higher amounts certainty not out of the question especially with any embedded thunderstorms. This could lead to poor drainage flooding issues as well as minor rises on area waterways, though the dry antecedent conditions should be a mitigating factor here. && .LONG TERM /THURSDAY THROUGH SUNDAY/... A mid-level closed low over Upper Great Lakes region Thursday will move towards the eastern Great Lakes region while opening up as a weaker wave by Friday. Deep, southerly flow and tropical moisture with become squeezed over the eastern seaboard, between the advancing trough and a prominent Atlantic ridge. Post T.S. Beryl will weaken and move northeast of the region Thursday. This surface reflection will become elongated near the eastern Lake Ontario region and heavy showers and thunderstorms are possible through Thursday afternoon. Drier air will work into western NY Thursday, however diurnally driven circulations will trigger some showers and thunderstorms through the early evening. The axis of tropical moisture will be east of the forecast area Friday. Drier air will continue to move into the region, however the mid-level wave will be overhead and diurnally driven showers and thunderstorms will be possible, albeit the threat of heavy rain will be less. A mid-level ridge will move across the region Friday night through Sunday and mostly dry conditions are expected across the region. There is a low chance of showers in the afternoon through early evening Saturday and Sunday, mainly inland from the lakes and near lake breeze boundaries. && .AVIATION /21Z SUNDAY THROUGH FRIDAY/... Surface high pressure slowly moving across the region will guarantee fair and largely VFR weather through Monday. The one exception to this will be in and around any valley fog that develops in the Southern Tier late tonight. This will likely cause reductions to vsbys down to IFR at KJHW between 07z/08z to 12z. Any fog will then quickly lift and dissipate after sunrise Monday, with a return to areawide VFR. Outlook... Tuesday..Mainly VFR. A low chance of showers and thunderstorms. Wednesday...MVFR with showers and thunderstorms likely. Restrictions to IFR possible in heavy showers. Thursday...Restrictions possible with a chance of showers and thunderstorms. Friday...Mainly VFR with a low chance of showers and thunderstorms. && .MARINE... High pressure across the Lower Great Lakes will drift east to New England Monday...then off the east coast Monday night and Tuesday. This will bring a period of generally quiet weather and light winds/minimal wave action through Tuesday. The light prevailing flow will allow local lake breeze circulations to once again develop during Monday afternoon. More unsettled conditions - featuring widespread rain and some embedded thunderstorms - are then expected to develop on Wednesday as an area of low pressure (the remnants of Tropical Cyclone Beryl) tracks northeastward across the Ohio Valley. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...RSH NEAR TERM...RSH SHORT TERM...PP LONG TERM...HSK AVIATION...JJR/PP MARINE...JJR