Area Forecast Discussion
Issued by NWS Buffalo, NY
Issued by NWS Buffalo, NY
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118 FXUS61 KBUF 022031 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 431 PM EDT Tue Jul 2 2024 .SYNOPSIS... High pressure will move off into New England this afternoon while maintaining fair dry weather. A deepening southerly flow between exiting high pressure and an approaching cold front will support mid summer heat and humidity to return on Wednesday. Showers and thunderstorms (many with drenching downpours) will then make their way into our region later Wednesday and Wednesday evening. Dry weather will then return for the Independence Day holiday. && .NEAR TERM /THROUGH WEDNESDAY/... Fair dry weather will continue this afternoon with exiting high pressure. There are a few high clouds spreading east across NYS due to a decaying upstream MCS. A warm front will enter the area tonight and may produce a sprinkle or isolated shower. Although, it is very likely that we will only see an increase in mid to high clouds. Very low PoPs (< 20%) considering Bufkit profiles do show a very prominent dry layer between 5K and 10k feet. Otherwise, not quite as cool with lows generally in the 60s. A few reading may dip into the 50, this would be for locales well inland east of Lake Ontario (Lewis Co). Wednesday is then GUARANTEED to be very warm and moderately humid... as a deepening southerly flow increases ahead of an approaching cold front. This will prompt Tds to return to the mid and upper 60s...while PWAT values will surge to around 2 inches. As is most often the case during the summer...the approaching cold front will be preceded by a pre-frontal sfc trough. This will help to initiate some thunderstorms over the Southern Tier and western Finger Lakes during the afternoon...then more widespread convection can be expected late in the day into the evening with the cold front. Forecast bulk shear of 40kts or so will increase the risk for organized convection that could produce gusty winds...particularly over southern areas. SPC highlights the most favored area for severe weather to be well to our southwest...in the vcnty of the Ohio valley. Temperatures on Wednesday will top out between the 85F to 90F range ...with the higher end of that range expected for the lake plains where heat index values will approach the mid 90s. Wednesday night...showers and storms will dwindle as the cold front settles south of the Lower Lakes overnight. Otherwise...not overly cool behind this front with lows generally found in the 60s. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... Weak cold frontal boundary will continue to press southeast through the region Thursday. A few showers or a thunderstorm will be possible closer to the New York/Pennsylvania state line, especially if the front slows down and does not clear the area by afternoon. Otherwise drier air advecting in behind the front will keep the remainder of the area dry. Not much of a push of cooler air behind the front, so temperatures Thursday still will be warm with highs mostly in the lower to mid 80s, but humidity levels should slowly drop off through the day. Dry conditions should continue Thursday night with the boundary to our south, although the boundary will start to makes its way northward as a warm front with at least some small risk for some convection working back into the Southern Tier late Thursday night. Warm frontal boundary will continue to make its way northward through the region Friday with temperatures following suit with highs in the mid to upper 80s, with the warmest heat index values approaching 90F. With the very warm and humid air mass in place, a few showers and thunderstorms may develop, mainly across western New York. A better convective signal exists for the Friday night period, anchored by the arrival of organized forced ascent associated with a mid level wave shortwave tracking eastward from the upper Midwest into the Great Lakes. && .LONG TERM /SATURDAY THROUGH TUESDAY/... The low pressure system that brought widespread showers Friday night will become vertically stacked across the upper Great Lakes by Saturday morning, causing it to weaken as it tracks northeast into Quebec. The system`s cold front will be in the process of marching east through western NY Saturday morning, with a mid/upper level dry slot following in its immediate wake. While showers and possibly a few thunderstorms should be ongoing Saturday morning across the North Country Saturday ahead of the front, confidence is lower in whether or not the dry slot will extend far enough north to bring a period of drier weather to our eastern zones by the afternoon. Have therefore undercut NBM PoPs by a small amount across WNY in the morning to better indicate the expected dry interlude, before additional synoptic moisture out ahead of the main trough axis combines with diurnal heating in the afternoon to increase shower/thunderstorm chances. While temperatures Saturday will likely depend on the exact timing of the front in the morning, highs are expected to generally range from the upper 70s to the mid 80s, warmest across the Finger Lakes region and in the Genesee Valley. The mid-level trough axis and moisture starved secondary cold front will swing through the region Saturday night. An area of high pressure subsidence building in its wake will lead to sharply decreasing chances for showers and thunderstorms from west to east overnight, with just a low-end chance lingering across the North Country by Sunday morning. Lows Saturday night will range in the 60s with lower overall humidity. Surface high pressure centered to our south along with a flattening mid-level ridge moving through the Great Lakes will then crest over our region through Sunday night, ensuring fair dry weather to cap off the weekend. Highs Sunday will be comfortable in the 70s to low 80s, with lows Sunday night in the low to mid 60s. Unsettled weather returns for the work week as weak high pressure is gradually replaced by yet another broad, weakening trough across the Great Lakes. While Monday is expected to be mainly dry as the eastern Great Lakes looks to be sandwiched between areas of deeper moisture to our west and along the East Coast, some diurnal shower activity can`t be completely ruled out. The next large scale system will come sometime Monday night into Tuesday as a shortwave trough moves out of the Ohio Valley, partially phasing with the longwave trough over the Great Lakes as it moves into the forecast area. Could see PoPs being raised into lkly territory for parts of the area with subsequent updates as timing discrepancies are better refined, but at this range will stick to Chc. Otherwise, the position of the high to the east should give temps a solid boost Monday back into the mid and upper 80s across the Lake Plains, cooling off again slightly for Tuesday. && .AVIATION /21Z TUESDAY THROUGH SUNDAY/... High pressure will produce VFR through the entire area this afternoon. Tonight, a warm front will work through the area overnight. It might bring with it a sprinkle or shower but VFR is expected to be maintain. Outlook... Wednesday...VFR, then MVFR with showers and thunderstorms late Wednesday afternoon and Wednesday night. Thursday...Mainly VFR with a low chance of a shower or thunderstorm across the western Southern Tier. Friday and Saturday... Mainly VFR with a chance of showers and thunderstorms. Sunday...VFR && .MARINE... High pressure will bring light winds and minimal wave action thorugh this evening. High pressure exits tonight and a warm front will work across the lakes overnight. Winds will pickup late out of the south pushing higher wave action off shore as we move into Wednesday. A cold front will approach the region Wednesday. Winds will veer to the southwest ahead of the cold front. While fair weather will remain in place through at least midday...there will be an increasing risk for thunderstorms in the afternoon and evening. In the wake of the cold front...fair weather will return to the region later Wednesday night with subsiding southwest breezes. Looking ahead to the Fourth of July...gentle to moderate winds will be in place throughout the region. These winds will be from the southwest on Lake Erie and primarily from the west on Lake Ontario. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...AR/EAJ/RSH NEAR TERM...AR/EAJ/RSH SHORT TERM...TMA LONG TERM...PP AVIATION...AR/EAJ MARINE...AR/EAJ/RSH