Area Forecast Discussion
Issued by NWS Buffalo, NY

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356 FXUS61 KBUF 191052 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 652 AM EDT Sun Aug 19 2018 .SYNOPSIS... High pressure will provide dry weather with comfortable humidity and seasonal temperatures through Monday. An unseasonably deep low pressure system is forecast to shift west then north of New York through Tuesday. This storm will bring widespread showers and chances for thunderstorms with heavy rainfall possible. A few showers may linger into Wednesday before another area of high pressure brings a return of fair weather Thursday and Friday. && .NEAR TERM /THROUGH TONIGHT/... Satellite imagery this morning shows some patches of low clouds across portions of western NY with more widespread low cloud cover over the Finger Lakes into CNY. Clear skies are in place east of Lake Ontario. Some thin high level smoke is also likely lingering but is not being picked up by IR imagery. High pressure is centered over central Quebec with a surface ridge extending southwest into into the lower Great Lakes. This ridging is providing for rain-free conditons with light winds. River valley fog across the western Southern Tier will dissipate through the morning hours. It will be less humid today under northeast flow with dewpoints running within a few degrees either side of 60F and comfortable air temperatures topping out in the mid 70s to lower 80s. Outside of some lingering morning stratus then diurnal cumulus developing inland from the lakes, some high level smoke from western wildfires may again be observed across our area as suggested by the HRRR Vertically integrated smoke model. Tonight, the center of high pressure shifts over Newfoundland with fair weather continuing. Look for mainly clear skies for most with some low stratus possibly limited to the interior western Southern Tier. River valley fog is expected to again develop with just light southeast winds. Lows will again dip to within a few degrees of 60. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... Monday surface high pressure over New England will continue to influence our region with fair weather, mostly sunny skies and temperatures rising into the upper 70s and lower 80s. The weather pattern will turn more active Monday night through Wednesday as a season strong storm system, and impacts along its associated warm and cold fronts pass through our region. Monday night an upper level low will be spiraling towards the Central Great Lakes from the mid Mississippi Valley. This feature will bring a surface low to near southern Lake Michigan, with a warm front extending eastwards towards WNY. Rain showers developing within instability aloft will be possible near Lake Erie and inland across the Niagara Frontier and So. Tier after midnight...with rain becoming likely across Chautauqua county by the start of Tuesday. Showers and a few thunderstorms will expand across our region through the day Tuesday as another shortwave dipping southward from Canada produces height falls aloft, deepens the surface low and enhances low level convergence. Aiding in lift will be the right entrance region to a 110 knot 250 hPa jet whose axis will be oriented northeastward across southern Ontario and Quebec. Morning clouds and rain showers will limit the amount of daytime destabilization, though with the surface low now deepening as it passes by to our NW, it will enhance the low level wind field such that there may be a risk for severe thunderstorms later in the day Tuesday. This will most likely be well south of the warm front, and ahead of an inbound cold front...across the Ohio Valley and towards the western So. Tier...which is presently outlined in a Slight Risk for Severe Storms by SPC. Of concern also will be heavy rain, with PWATS again nearing 2 inches. The increase in low level winds will keep storms moving, but any training of storms over the same region could bring an isolated flood threat. A surface cold front will cross our region Tuesday night with additional showers...though very little instability aloft will limit thunder chances. Another jet aloft, this across the Ohio Valley...whose left exit region will be near our region will again bring additional synoptic lift to aid in precipitation formation. Behind the front 850 hPa temperatures will lower into the single digits Celsius across much of the region by the end of Wednesday. The axis of an upper level trough will pass across the region Wednesday, maintaining chances for scattered showers. The cooling aloft will also bring a response from the lakes, with lake enhanced showers downwind of the lakes. Bountiful clouds through the day Wednesday combined with the pool of cold air aloft will make this a cool day, with highs in the upper 60s to lower 70s...which is 5 to 8 degrees below normal. Drier air building towards the region Wednesday night combined with the pool of cold air aloft being displaced to the east will end much of the showers...though a slight chance for a few lake effect sprinkles or light rain showers will continue. && .LONG TERM /THURSDAY THROUGH SATURDAY/... This period will feature a return to pleasant weather as high pressure ridging aloft builds towards the Eastern Great Lakes behind a recently departed mid level trough of low pressure. Thursday will start cool with a few nuisance lake effect clouds, and possible sprinkles/light showers starting the day. The building ridge will bring day to day increasing warmth, with highs in the mid 70s Thursday topping out in the mid 80s by Saturday. Humidity will remain comfortable through the period, and it will not be until Saturday, ahead of another storm system that some stickiness returns with dewpoints rising into the lower 60s. A few showers will be possible later in the day Saturday as another shortwave rides through the Central Great Lakes and towards James Bay. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... VFR ceilings with patches of lower level stratus are showing up across portions of western NY and the Finger Lakes region. VFR is expected to continue this morning at most terminals. Saturated ground from recent rainfall and calm to light winds has led to patches of fog and low stratus mainly in the western Southern Tier river valleys including some IFR at KJHW. Surface ridging from high pressure over eastern Canada will continue to provide fair weather through today and into tonight. Some VFR level diurnal cumulus is likely inland from the lakes while high level smoke will likely linger from western wildfires. Some river valley fog may again develop across the western Southern Tier late tonight possibly impacting KJHW. Outlook... Monday...VFR. Tuesday...MVFR. Showers and thunderstorms likely. Wednesday and Thursday...Mainly VFR. A chance of showers. && .MARINE... High pressure will continue to provide for fine boating conditions on the lakes today and Monday. On Tuesday a unseasonably deep surface low is forecast to track north across the central Great Lakes with southerly winds picking up on the eastern Great Lakes. There is a chance of advisory level winds and waves but the southerly direction should direct the worst into Canadian waters. A sharp cold front is forecast to cross the lower Great Lakes Tuesday night which will bring westerly winds and higher waves. Small craft advisories are most likely on Wednesday for the eastern end of Lake Ontario. High pressure will return for the end of the week with a return of fair conditons. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Smith NEAR TERM...Smith SHORT TERM...Thomas LONG TERM...Thomas AVIATION...Smith MARINE...Smith is the U.S. government's official web portal to all federal, state and local government web resources and services.