Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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742 FXUS61 KBUF 211825 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 225 PM EDT Sat Sep 21 2024 .SYNOPSIS... An upper level disturbance will cross the area, producing scattered showers and a few isolated thunderstorms, mainly through this evening across Western New York, the Genesee Valley, and Finger Lakes. A narrow ridge of high pressure will then bring a return to dry weather Sunday. The weather will then turn unsettled, as a cold front moves into the area Monday and stalls out, with several areas of low pressure moving northeast along it through the course of next week, with numerous rounds of showers and a few thunderstorms. && .NEAR TERM /THROUGH SUNDAY/... A mid level shortwave within northwest flow aloft will cross the eastern Great Lakes through this evening. Modest diurnal instability has developed this afternoon with surface-based CAPES nearing 1500 J/Kg. This combined with the forcing from the incoming shortwave will produce an increasing coverage of showers and a few thunderstorms. HREF/HRRR suggesting the best coverage will be across the Genesee Valley/western Finger Lakes and interior Southern Tier through about 8 PM this evening. A few showers may reach the eastern Lake Ontario region, but coverage here should be much less. The evening showers/storms will faded by mid to late evening with loss of heating and exiting shortwave, with any remaining spotty showers ending before daybreak Sunday morning. Some clearing along with light winds overnight will promote areas of fog, especially across the Southern Tier and western New York, and in any areas which receive rainfall through this evening. Any morning fog and low stratus will burn off by mid morning, leaving a mix of sun and clouds for the rest of the day with dry weather prevailing as a narrow ridge builds into the eastern Great Lakes. Temperatures will remain above normal with most highs in the mid 70s to around 80. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... A well defined closed low over the desert Southwest this early morning will open up with a piece of energy transversing the Plains, and phasing with a northern branch jet to bring enhanced synoptic lift for the formation of showers late Sunday night and through Monday. Deeper moisture will be near the surface low along a stalled frontal boundary...with this low just to north of Lake Erie. This will allow for rainfall amounts Monday and Monday night for most areas to remain a third of an inch or less...with heavier rain just to our west and north. With this low remaining to our west, surface winds will generally remain south to southeast, with the downslope regions near Lake Erie/Thruway and along the southern Lake Ontario shoreline likely to top the 70 degree mark Monday, while cloud cover over higher terrain will keep the interior higher terrain of WNY and the Tug Hill in the lower to mid 60s. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Pattern this period will feature unsettled weather throughout. Aloft a 250/300 hPa southern branch of the jet stream will lift northward towards the Ohio Valley, while a northern branch jet within a developing long wave trough will be dropping over the Prairies of Canada and into the Northern Plains. In an amplifying pattern, these jets will help to close the upper level trough over the Plains/Midwest region, which will linger unsettle weather through the remainder of this period. Where this closure occurs is still with great uncertainty among the models, increasing further the uncertainty in the weather towards the end of this period. Will carry chance to likely PoPs each day through this period. Wettest period may end up being Tuesday night into Wednesday as a stronger LLJ of 30 - 35 knots, and surface warm front moves across the region. Marginal instability will allow for a risk of thunder through Thursday, though none of the days is overly convincing for thunder chances. Cloud cover and showers will keep daytime highs close to normal, while these same clouds will hold overnight lows above normal through the period. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... A mid level shortwave will cross the region bringing with it a period of cloudiness with VFR bases and scattered showers through this evening. Most of the shower activity will be from western New York to the Finger Lakes. Overall, coverage of the showers will stay scattered to widely scattered, with the best chance of a more organized cluster of showers across the Genesee Valley and Southern Tier between 19z and 24z. There may be a few isolated thunderstorms as well in this area. Given the expected scattered nature of showers, and even more sparse coverage of thunder, used VCSH in the TAFs for now. Tonight, any remaining showers will taper off and end, and skies will partially clear. The light winds and clearing skies will allow areas of IFR fog and low stratus to develop, especially across the Southern Tier and Finger Lakes valleys and in any locations that receive rainfall today. KJHW is the most likely terminal to experience fog and IFR overnight through Sunday morning. Outlook... Sunday...Patchy IFR fog and low stratus through mid morning, then mainly VFR. Monday through Thursday...VFR/MVFR with showers likely and a chance of thunderstorms at times. && .MARINE... East to southeast winds will continue through the weekend on the lower Great Lakes, directing most of the moderate chop into the middle of the lakes and Canadian waters. Low pressure and a cold front will approach from the west late Sunday night and Monday, with increasing south to southeast winds on both lakes. This wind direction will once again keep the greater wave action well offshore and in Canadian waters. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Hitchcock/TMA NEAR TERM...TMA SHORT TERM...Thomas LONG TERM...Thomas AVIATION...Hitchcock/TMA MARINE...Hitchcock