Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 160819 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 419 AM EDT Tue Aug 16 2022 .SYNOPSIS...
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A weak upper level low will meander across the Northeast States today through Thursday, bringing unsettled weather with a few showers and widely scattered thunderstorms at times. Dry weather will return Friday as high pressure builds back into the eastern Great Lakes.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Radar imagery early this morning showing an area of showers over northwest PA drifting northwestward, clipping the southwest corner of NY state. This area of showers will likely move a little farther north and west through early this morning, with a period of showers for Chautauqua and southern Cattaraugus counties. Elsewhere, a few sprinkles and spotty light showers are found from the western Finger Lakes westward to Lake Erie. A broad/weak upper level low over eastern NY/PA this morning will drift slowly east into southern New England and gradually deepen through Wednesday morning, with an associated surface low deepening off the New England coast. The better forcing and deeper moisture will be found east of the upper level low and off the east coast through the period. Meanwhile, large scale forcing across our region will be weak and stochastic as subtle, convectively modulated vorticity maxima orbit the upper level low. At the surface, there will be very little in the way of a synoptic scale feature, with mesoscale boundaries dominating. Expect the primary low level focus to be terrain induced boundaries and weak circulations over the Southern Tier and western Finger Lakes this afternoon. Most of the showers through the morning hours will continue to focus across the western Southern Tier near a weak inverted trough axis. This afternoon diurnal instability and local terrain forcing will take over, with showers becoming more numerous across the Southern Tier and western Finger Lakes. Enough instability will develop to support a few widely scattered thunderstorms as well. Farther north, a stabilizing northeast flow off Lake Ontario will likely keep areas along and north of the NY Thruway mainly dry from Wayne County westward across Rochester and Buffalo. East of Lake Ontario, high- res guidance suggests a few terrain induced showers will develop over the Adirondacks and then drift westward towards the east end of Lake Ontario during the afternoon and early evening. This evening the areal coverage of showers will diminish, and any thunder will end. Overnight, model guidance suggests another weak inverted trough will drift across northwest PA and southwest NY, supporting the chance of a few scattered showers. Increasing lake induced instability may also support a few scattered showers over Lake Ontario and Lake Erie, possibly drifting onshore at times across Western NY.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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Heading into Wednesday, a broad negatively tilted trough will lie across much of the Great Lakes and New England, where it`s within this trough a closed low will deepen and engulf much of New York State and spread eastward into Cape Cod. Throughout the day this closed low will ever so slightly advance northward into New England. As such, with the the close proximity of the low with respect to the region, weak flow will remain across the region and any forcing in place across the area will primarily be diurnally driven and therefore expect any showers and thunderstorms to form by Wednesday afternoon. The aforementioned upper level closed low over New England will meet up with a coastal low Thursday, where by Thursday night both features will become vertically stacked. This being said, the lower Great Lakes region will remain of the backside of the low pressure system which will produce a marginal lake response as winds back more north-northwest Wednesday night into Thursday and therefore kept the slight chance and chance for lake effect rain showers Wednesday night into Thursday. Additionally, later on Thursday diurnally driven showers/thunderstorms will be possible once again. Thursday night, the stacked low pressure system will continue to progress north into the Canadian Maritimes allowing for some upper level ridging and surface high pressure to spill across the Great Lakes. With the incoming ridging and surface high pressure, expect mostly dry conditions Thursday night.
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&& .LONG TERM /FRIDAY THROUGH MONDAY/...
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Another potent shortwave trough will dive south from the Canadian Prairies and into the Upper Midwest Friday. Similar to the low pressure system earlier in the work week, this feature will closely follow suit by closing off and slowing down its progression across the Upper Mississippi Valley through the first couple of days of the weekend. On the bright side, the slowing progression of the trough will support ridging, surface high pressure and consequently a period of dry weather across the region Friday through most of the day Saturday. As of 00Z model guidance packages arrive, the weakening upper level low is progged to track east late Saturday and Saturday night which would support a chance for some scattered showers Saturday night, mainly across Western New York. Then increasing moisture along with diurnal heating will support better chances for showers and thunderstorms Sunday afternoon, though the best opportunity for showers and storms will arrive as the system nears the area at the start of the next work week.
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&& .AVIATION /08Z TUESDAY THROUGH SATURDAY/...
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A weak upper level low will continue to meander across NY/PA and New England today through tonight, producing scattered showers at times. Through the morning hours the majority of the showers will focus across the western Southern Tier. The greatest coverage of showers will occur this afternoon and early evening across the Southern Tier and western Finger Lakes as modest diurnal instability develops, although a few spotty showers are also possible outside of this time and space as well. Enough instability will develop this afternoon to support a few isolated to widely scattered thunderstorms. Any thunder will end in the evening, with showers decreasing in coverage. VFR will prevail most of the time, although any heavier showers may produce local/brief MVFR to IFR conditions. Some patchy fog may develop across the Southern Tier later tonight through early Wednesday morning with local IFR VSBY. Outlook... Tuesday night through Thursday...Mainly VFR. Chance of showers and isolated thunderstorms with local/brief flight restrictions. Friday and Saturday...VFR.
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&& .MARINE...
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High pressure will remain anchored over Quebec today through Wednesday, with general low pressure over the southeast states and along the east coast. This will maintain an extended period of northeast winds on Lake Ontario and Lake Erie. Sustained wind speeds will generally be 10-13 knots, producing a light chop at times. Forecast BUFKIT soundings over Lake Erie and Lake Ontario dont support a chance of waterspouts today through this evening with lake induced equilibrium levels too low. That will change overnight as mid level temperatures cool and allow for deeper lake induced instability to develop, bringing the chance of waterspouts by late tonight and Wednesday morning.
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&& .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Hitchcock NEAR TERM...Hitchcock SHORT TERM...EAJ LONG TERM...EAJ AVIATION...Hitchcock MARINE...Hitchcock

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