ITHACA, N.Y. — It could be a rough couple of days ahead for Upstate New York. A storm system will stall out over the Northeast, and the tropical humidity in tandem with oceanic moisture flow will produce frequent heavy downpours and strong thunderstorms tonight and tomorrow. Flood Watches have been issued for most of the eastern half of the state.
Moderate to locally heavy rainfall 🌧️ is continuing late this afternoon over the Wyoming Valley, Poconos & Catskills. Additional sct'd t'storms are developing over the Finger Lakes with locally heavy rain and⚡️. Please pass on any reports of flooding or significant WX #NYWX #PAWX pic.twitter.com/apSqJf19t6— NWS Binghamton (@NWSBinghamton) July 9, 2023
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A low pressure storm system will stall out over Quebec and Eastern New York, and plumes of heavy rain with embedded thunderstorms, some of which could be severe, will drench much of the eastern half of the state over the next 36 hours. Tompkins County will be on the western fringe of the main moisture plumes, and with periods of heavy rain and thunderstorms through the rest of today, tonight and Monday, about 1.00-1.50″ of rain is expected. That’s a soaking, and liable to cause some isolated cases of urban/small stream flooding, but not a major risk to health and safety. A few severe thunderstorms may produce frequent lightning, brief gusty winds and small hail, so be mindful of any light lawn decorations or loose tree branches overhead.
The much bigger concern will be areas from Binghamton eastbound, including the Catskills, Hudson Valley and Capital Region. Models suggest 6 inches or more of rainfall may fall in some of these areas, basically two months of rain in two days. Numerous instances of flash flooding are expected, with significant risks of areal and river flooding as well. If you are planning to travel to New York or Albany tonight or tomorrow, be very careful, as roadways will be at serious risk for ponding, streambank overflows, and potentially even washouts of the road bed itself. Remember to go slow, be wary of hydroplaning, and if there is water pooling on the road, don’t assume it’s shallow enough to pass – “turn around, don’t drown”.
Turning back to Tompkins County, most of the rain should fall this evening and earlier tonight; some scattered showers and thunderstorms will continue through the day tomorrow, but the large majority of precipitation will be in the next eight hours. Along with periods of heavy rain this evening, it will be warm and humid, with temperatures now in the mid 70s only falling to lows in the mid 60s tonight, with light and variable winds.
Monday sees less significant scattered showers and storms, with the bulk of activity further east. Highs will be in the upper 70s with mostly cloudy skies between storm cells, and winds turning to the northwest as the frontal boundary grinds further eastward. Monday night will see less humid and more tolerable conditions, with partly cloudy skies and lows in the lower 60s.
Tuesday will offer a brief break before a reinforcing cold front approaches from the west for Wednesday. Expect mostly sunny skies with somewhat humid conditions and highs in the upper 80s. Tuesday night will be mostly clear, with increasing clouds towards sunrise Wednesday, with lows in the lower 60s.
Wednesday sees the cold front move in, with PM shower and thunderstorms likely. Rainfall amounts will be light to moderate, and not pose any major flooding risks. Skies will become cloudier during the day, with highs in the mid 80s. Wednesday night will see scattered showers continue throughout the night, with near-overcast skies and lows in the mid 60s.
Thursday sees a shortwave “pulse of instability” ride along the frontal boundary, and this will lead to more unsettled weather. Expect scattered and thunderstorms, some of which may produce gusty winds or small hail, mostly cloudy skies, and highs in the low 80s. Thursday night. The thunderstorms whittle away as daytime heating is lost Thursday night, but showers should continue through the night, with mostly cloudy skies and lows in the mid 60s.
Unsettled conditions will continue for at least the rest of the week as a strong cutoff low slowly spins over the Western Great Lakes, causing shortwaves to spin around it like the spokes of a wheel. Friday will host scattered showers and thunderstorms with highs in the mid 80s, and showers overnight with lows in the mid 60s. Saturday and Sunday will also see rounds of showers and thunderstorms during the day, with partly to mostly cloudy skies between cells. Highs will be in the low to mid 80s, with lows in the mid 60s.
Looking into the second half of July, once the Great Lakes cutoff low begins to pull off to the northeast, warmer temperatures are expected to make their way back into the Northeast, while unseasonable wetness continues. Texas and much of the south will continue to swelter under the heat dome, and all of the country except parts of Alaska and the Pacific Northwest is expected to have temperatures above normal.