ITHACA, N.Y. — Everyone enjoys saving on their heating bills and heading outdoors with the unusually warm late fall we’ve been having, but all good things must come to an end. As a colder jet stream pattern takes hold across the country, temperatures will be chilly as lake effect rain and snow pose a near-constant threat through the week.

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At present, a broad area of low pressure extends from New England to Quebec. Since this system, which ushered in heavy rains at the beginning of this weekend, is to Ithaca’s east, and air circulates counter-clockwise around lows in the Northern Hemisphere, that means northerly flow is ushering in cold Canadian air into Tompkins County.

This cold air crossing over Lake Ontario is generating some light lake effect snow and rain showers, but temperatures in the mid to upper 30s are preventing the snow from sticking. at least for now. Models initially suggested a high in the low to mid 40s in the Ithaca area today, but it looks like we’ll fall short of that this afternoon due to persistent mostly cloudy to overcast skies.

The wind angle (fetch) will shift to a more westerly direction tonight, which should reconfigure downstream lake effect bands towards Syracuse, which will likely see some light accumulations as temperatures dip below freezing – as we’re getting into winter, do be mindful of untreated, slick roads and give yourself extra time for your travels. As for Tompkins County, a few flurries are likely tonight, with partly cloudy skies and lows in the mid to upper 20s.

Brief high pressure builds in from the northwest for Monday, and drier, more stable air should squelch lake effect for Monday. Expect partly to mostly cloudy skies with highs in the low 40s. Monday night will be cold but quiet. with lows in the low to mid 20s.

The next storm system is slated to cross the area later Tuesday, a low pressure center that will move from the Mississippi River Valley into the Mid-Atlantic states. The precipitation shield’s northern flank is expected to spread across Tompkins County, enhanced by a secondary low that develops across the Great Lakes and moves eastward into the Atlantic. The bulk of precipitation should hold off until after sunset Tuesday, though a few afternoon rain showers are possible, with mostly cloudy skies and highs around 40.

Tuesday night is likely to be a mixed event, with rain showers changing over to snow during the evening, and persisting as snow until around sunrise when they change back over to rain. Lows will be around 32, and the atmospheric profiles don’t support a wintry mix at this time. Do expect around a coating to an inch by Wednesday morning, maybe 2″ on the hilltops outside Ithaca.

If you don’t brush it off the car during the morning, it’ll melt off during the day Wednesday, as the snow changes back to rain around sunrise and Wednesday warms up into the mid 40s, though it’ll continue to be an unsettled day with on-and-off light rain showers. The pair of lows merge off New England and continue ENE later Wednesday, which will tamp down the shower action overnight. The lingering showers will change over to snow, with little to no accumulation, as lows Wednesday night dip into the upper 20s.

On the backside of the lows, renewed northwesterly glow Thursday will usher in another round of lake-effect showers, which will be in the form of rain during the day. Skies will be mostly cloudy with highs in the low 40s. Thursday night will see those showers change over to snow, though accumulations will be light if there is any at all. Skies will be mostly cloudy with lows in the lower to mid 20s.

High pressure over Montana and the Lower Mississippi create an environment that’s very conducive for unseasonable cold across the Eastern United States Friday. It will be below average in Tompkins County, though not as bad as communities to the west. Skies will be partly cloudy with highs around 40. Friday night will see a few lake effect snow showers south and southeast of Lake Ontario, and a very cold overnight with lows in the low 20s, and perhaps some teens in the outlying areas.

Looking into next weekend, it will be dry but brisk. Expect partly cloudy skies both Saturday and Sunday, with highs in the upper 30s to around 40 both days, and lows in the low to mid 20s during the overnight hours.

Graphics courtesy of the NOAA Climate Prediction Center

Extended Outlook

Looking forward towards the Thanksgiving holiday and associated travel period, the long-term forecast calls for a cold but dry pattern. With the highs over the Mountain West and Mississippi Delta, a pronounced trough in the jet stream will be reinforced with dry but freezing polar air from continental Canada. While it’s unlikely to be as bad as the subzero Thanksgiving a few years back, it will be below normal and the initial outlook for travel looks smooth from a meteorological standpoint.

Brian Crandall

Brian Crandall reports on housing and development for the Ithaca Voice. He can be reached at bcrandall@ithacavoice.com.