Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 151039 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 639 AM EDT Wed Aug 15 2018 .SYNOPSIS... Weak high pressure ridging over New York will support warm and humid weather for today with just a few isolated chances for a shower or thunderstorm. Widespread unsettled weather will then return for Thursday and Friday as a complex area of low pressure will cross the Lower Great Lakes. Dry and seasonable weather is then expected this weekend. && .NEAR TERM /THROUGH TONIGHT/... Surface ridging extends north across New York this morning stemming from high pressure centered over West Virginia. Satellite imagery shows mainly clear skies over much of western NY and central NY outside of some patches of fog and low stratus. A low amplitude mid- level level ridge axis will become more zonal with time as it passes over our region today. This will promote mainly dry weather today with elevated dewpoints in the 60s to 70F supporting rather uncomfortable humidity levels. There are some low chances for some isolated to scattered showers and thunderstorms that remain in the forecast for this afternoon during peak heating. Developing lake breeze boundaries could lead to a few of these showers and storms inland from the lakes. There is also a risk in place across the North Country and into the SLV ahead of an approaching weak frontal boundary sagging south toward Lake Ontario. CAPE is forecast to reach 1000-2000 j/kg ahead of the front with 30-40kts of effective bulk shear. This may bring an isolated strong to severe thunderstorm in the North Country where SPC has placed a marginal risk area. Otherwise, temperatures are expected to run a few degrees above normal with afternoon highs ranging from the lower 80s across the higher terrain to the mid and upper 80s across the lower elevations. This evening, some lingering low chances fora shower or storm will remain in place ahead of the weak cold front dropping across the Saint Lawrence Valley and North Country. Otherwise dry weather is expected overnight for the remainder of central NY and most of western NY. Moisture transport and warm advection ahead of a warm front will allow for a chance for a few showers approaching Western NY by daybreak Thursday. The elevated humidity will make for another warm and muggy night, with lows in the upper 60s to around 70 near the lakes, and low to mid 60s in the cooler Southern Tier valleys and Lewis County where some more patchy fog may develop again. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Confidence remains high in an unsettled and rather wet pattern during this period. Short term models are in good agreement showing the Central Plains upper low opening and lifting northeast into the lower Great Lakes during Thursday with another wave moving into the region from the upper Midwest Thursday night into Friday. Precipitation chances will increase Thursday as a surge of moisture pushes into the region. This will spread showers and scattered thunderstorms into western New York around mid day, reaching the Genesee Valley and western Finger Lakes during the afternoon. Highs will reach the lower to mid 80s in most locations prior to the arrival of steadier showers. Coverage of showers and embedded thunderstorms will become fairly widespread Thursday night and Friday as a surface low tracks over or just north of Lake Ontario. Robust moisture transport will send precipitable water values to near 2 inches. This will bring the risk for locally heavy rainfall and possible flooding concerns. WPC continues to highlight far western New York with a Day 3 Slight Risk of Excessive Rainfall, although this may be slightly overdone given the relative recent drier conditions in this part of the state and overall fragmented forcing profile. The system will slowly exit the area Friday night as the mid level trough eases southeast across the eastern Great Lakes. The heavy rain risk will end in the evening, with lingering showers slowly tapering off from northwest to southeast. && .LONG TERM /SATURDAY THROUGH TUESDAY/... Saturday the late week system will weaken and slowly exit off the New England coast. There may be enough lingering moisture and weak forcing to support a few more scattered showers or an isolated thunderstorm, mainly across the Southern Tier and points southeast and east of Lake Ontario. A somewhat less humid airmass will build into the region Saturday, with highs ranging from 75-80. Sunday through Monday weak high pressure will bring a return to dry weather across the eastern Great Lakes. It will remain warm, with highs in the lower 80s Sunday and mid 80s by Monday across lower elevations. Lows will generally be in the 60s on the lake plains and 50s in the cooler Southern Tier valleys and Lewis County. The next system will move into the Great Lakes later Monday night and Tuesday. A mid level trough and associated cold front are forecast to cross our region Tuesday, with the next chance of rain. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... A narrow area of surface ridging extends over western and central NY this morning. This has brought much drier air in with mainly clear to partly cloudy skies at all TAF sites in patches of fog and low stratus leading to some MVFR to IFR conditions. Fog and low stratus will dissipate shortly after sunrise with daytime mixing resulting in largely dry VFR conditions for the balance of the day. The possible exceptions to this will be during afternoon peak heating where lake breeze boundaries could lead to a few isolated to widely scattered showers and storms south of Lake Ontario. There is also a low risk for some isolated to scattered showers and storms possible ahead of an approaching weak cold front pushing south across the North Country and Saint Lawrence Valley. Brief/localized reductions to sub-VFR conditions will be possible with any shower or storm along with variable and gusty winds near storm outflows. There is a marginal risk for a strong to severe storm ahead of this front. There may be some lingering showers in the North Country this evening otherwise VFR expected outside of some more patches of possible fog overnight. Outlook... Thursday and Friday...Showers and thunderstorms with areas of attendant MVFR likely.. Saturday...Mainly VFR with a chance of a shower across interior sections. Sunday...VFR. && .MARINE... Isolated to scattered showers and storms are possible this afternoon and evening across the Saint Lawrence Valley as a weak cold front crosses the region. Otherwise, there will be little in the way of marine concerns through midweek with both winds and waves expected to remain safely below Small Craft Advisory levels. More unsettled conditions will then return for Thursday and Friday as another wave of low pressure crosses the Lower Lakes Region and brings a renewed potential for showers and thunderstorms. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Smith NEAR TERM...Smith SHORT TERM...TMA LONG TERM...Hitchcock AVIATION...Smith MARINE...Smith

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