Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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064 FXUS61 KBUF 091823 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 223 PM EDT Sun Jun 9 2024 .SYNOPSIS... An upper level trough will move through the area, producing widespread showers and scattered thunderstorms through early evening. Scattered showers and cool temperatures will continue tonight through Monday. High pressure will then build in, resulting in a drying and warming trend through Thursday. && .NEAR TERM /THROUGH MONDAY/... Early this afternoon, showers and a few thunderstorms are developing across the region. This is due to diurnal instability, combined with a compact shortwave which is rotating through longwave trough and dropping southward across the region. Initially showers/storms are developing along a convergence zone from the Niagara Frontier east across the Genesee Valley and Northern Finger Lakes, and along a boundary across the Saint Lawrence Valley. Mesoscale guidance in good agreement showing the area of showers expanding and dropping southward, following the progression of the shortwave. Model agreement and upstream radar trends provide high confidence in the development of showers which should have quite a bit of areal coverage. These will hold off until closer to sunset across the Southern Tier due to the north to south movement. While severe thunderstorms are unlikely, low freezing levels around 7k feet on the Buffalo 12Z sounding suggest a risk for small hail with any thunderstorms. Gusty winds can`t completely be ruled out either, but for the most part these won`t be much stronger than the 25 to 35 mph winds outside of the storms. Showers will decrease in coverage from northwest to southeast this evening as the vorticity maxima moves southeast of the area. Overnight, additional weaker shortwaves, deepening moisture, and even some lake induced instability will support a few more scattered showers, increasing in coverage towards Monday morning. A cool northwest flow with 850mb temperatures falling to +3C on Monday will result in the coolest day of the recent stretch of unsettled weather. Highs will mainly be in the upper 50s to lower 60s. Cyclonic flow aloft will result in lots of cloud cover and possibly a few showers although coverage will be limited. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As we move into Monday night any diurnally-driven shower activity will fade out during the early evening with the loss of heating. This same loss of diurnal influences and a continued sufficiently cool (925 T`s lowering to around +6C) and moist cyclonic NW flow may then support the development of some rare June lake effect/enhanced showers southeast of Lake Ontario during the late evening and overnight hours...though with some shear and a cap of only 3-5 kft in place...any such activity will remain rather spotty and weak. Otherwise a fair amount of lower clouds will linger...with the cool airmass also supporting below average lows ranging from the lower- mid 40s in our normal interior cool spots to around 50 near the lakeshores. On Tuesday surface-based ridging and drier air will build across our region. Coupled with renewed diurnal influences...this will help to bring about a quick demise to any spotty weak lake response southeast of Lake Ontario during the morning. The incoming drier airmass and daytime heating will also result in the lingering lower clouds evolving into a SCT-BKN diurnal cumulus field...with the coverage of the latter greatest inland from the lakeshores. Otherwise it will be dry...with some gradual airmass modification allowing highs to climb back into the mid to upper 60s...still below normal for this time of year...but also not as cool as those of the previous day. The surface high will then crest directly across our region Tuesday night...with its axis then only slowly drifting to a position just to our southeast during Wednesday. This will result in fair dry weather for this 24-hour period...along with partly cloudy to mainly clear skies Tuesday night...and mostly sunny skies Wednesday. With respect to temperatures...the overhead position of the surface ridge will support good radiational cooling Tuesday night...allowing lows to range from the mid 40s across the interior Southern Tier/North Country to the lower 50s across the lake plains of western New York. Warm advection/continued airmass modification will then allow highs to finally climb back to normal or slightly above normal levels on Wednesday...when most areas should see readings peak in the mid to upper 70s. Wednesday night the surface ridge will slide further east and off the mid-Atlantic coastline...while a weak to modest shortwave trough approaches our region from the northwest. Cannot rule out this latter feature producing an isolated shower or two as it approaches later Wednesday night...however conditions should remain largely dry. With a deepening southwesterly flow of warmer air in place between these two systems...lows Wednesday night will be much warmer than those of the preceding three nights...with mins ranging from the mid 50s across the interior to the lower 60s across the lake plains of western New York. && .LONG TERM /THURSDAY THROUGH SUNDAY/... A trough will deepen across the Great Lakes region as an upper level ridge builds across the Rockies late in the work week. A strong, southerly flow will promote warm weather Thursday through Friday. An area of low pressure is expected to track across northern Ontario and Quebec Thursday through Friday with a cold front impacting the region during this time. There is low confidence in the timing of the front, however this should bring a period of scattered showers and thunderstorms. An area of high pressure is expected to move into the region this weekend with medium confidence of dry, fair weather. Temperatures will be near to around five degrees above normal for Thursday through the weekend. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... A mid level trough will move southeast across the area, and combine with modest daytime instability and lake/terrain generated low level convergence boundaries to generate another area of showers and scattered thunderstorms crossing the area from north to south. Expect areas of MVFR CIGS/VSBY to develop, with local/brief IFR in thunderstorms. Thunderstorms may produce some small hail. The more organized showers and scattered thunderstorms will taper off this evening, although a few scattered showers may linger overnight. CIGS/VSBY should improve back to VFR initially in the evening, but areas of MVFR CIGS will likely develop overnight in stratus. This stratus will linger most of the day Monday, with MVFR cigs lasting into the afternoon hours at most locations. Outlook... Monday night through Thursday...Mainly VFR. Friday...VFR/MVFR. A chance of showers and thunderstorms. && .MARINE... Moderate westerly winds today, with another round of Small Craft Advisory conditions on both lakes. Winds will decrease on Lake Erie this evening, but Small Craft Advisory conditions will continue much of tonight on Lake Ontario. Winds will be somewhat lower Monday, but still expect choppy conditions on both lakes. More favorable winds and waves for boating will return by the middle of the week. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Beach Hazards Statement through Monday morning for NYZ004. Beach Hazards Statement through Monday morning for NYZ005>007. Beach Hazards Statement until 11 PM EDT this evening for NYZ010-019-085. MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ020. Small Craft Advisory until 11 PM EDT this evening for LEZ040-041. Small Craft Advisory until 5 AM EDT Monday for LOZ042. Small Craft Advisory until 11 AM EDT Monday for LOZ043>045. && $$ SYNOPSIS...Apffel/Hitchcock NEAR TERM...Apffel/Hitchcock SHORT TERM...JJR LONG TERM...HSK AVIATION...Apffel/Hitchcock MARINE...Apffel/Hitchcock