ITHACA, N.Y. — It’s a sweltering, stormy Sunday in Upstate New York. But some relief is on its way this week – a cold front will provide a brief bubble of cooler and less humid for Tuesday, and then more seasonable and less muggy conditions should work their way in in time for next weekend.

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Much of the region is under Heat Advisories as temperatures are in the 90s in most valley areas, with dewpoints in the mid to upper 60s that make it feel more like the upper 90s to around 100 degrees. In addition, because of the heat, humidity and unstable atmospheric conditions, a Severe Thunderstorm Watch has been issued through 10 PM tonight.

The abundant heat energy and favorable atmospheric dynamics thanks to a destabilizing low pressure storm system to the northwest mean that multiple strong to severe thunderstorms are likely to pop up around the region, including one Severe Thunderstorm Warning issued already for Northern Tompkins County. Some of these cells will be capable of golf-ball sized hall, damaging gusty winds of up to 70 MPH, and even a few isolated tornadoes. If a Severe Thunderstorm Warning is issued for your area, seek shelter and wait for the storm to pass.

This low pressure storm system will primarily work its way through the overnight hours tonight and into tomorrow morning, with the most significant precipitation falling between 12 AM and 6 AM. With the humid air, models suggest this could be a drenching overnight, 1.00-1.50″, though in recent weeks the models have tended to be more generous with precipitation amounts vs. reality. It will be near overcast overnight, and with the frequent rain and humidity, temperatures won’t cool off much, settling around 70 for an overnight low.

As the low’s associated cold front passes through in the morning hours, the rain will taper off and the skies will clear up, though a few lingering showers and storms are likely through the AM hours. By the afternoon, winds will have turned to a northwesterly breeze and temperatures will still be warm but more seasonable, in the lower 80s for highs. High pressure moves overhead Monday night, which will settle down the winds, and with only a few passing clouds, temperature overnight will be fairly comfortable for throwing open the windows, with lows in the upper 50s.

With high pressure staying overhead Tuesday, it should be a fairly pleasant summer day. Dewpoints will be in the upper 50s so humidity will be comfortable, with mostly sunny skies, a light northwest breeze, and highs in the low to mid 80s. Tuesday night will see partly cloudy skies with lows in the low 60s.

Wednesday will place Ithaca and Tompkins County on the back side of the high, which will usher in warmer and more humid southerly flow. With an incoming storm system from the west, there will be increasing clouds during the day. Temperatures will top out in the upper 80s with rather muggy conditions by late afternoon. As the storm system spins northeastward over Canada Wednesday night, there will be scattered showers and thunderstorms during the overnight hours as a shortwave pulse rotates around the low, but it will not a washout. It will be mostly cloudy with lows in the upper 60s.

Heading into Thursday, the cold front will begin to push through, but it will be fairly slow and models are trending drier with the atmosphere aloft. Some thunderstorms may fire off Thursday and Friday, but these will be fairly sparse, and the front will work in drier air that will tamp down thunderstorm development. Skies will be partly cloudy with decreasing humidity during the day Thursday, with highs in the upper 80s. It will be mostly cloudy with a few isolated storms overnight Thursday, with lows in the lower 60s.

Friday will see the front push through fully, and temperatures will fall a few degrees, topping out in the low 80s with a touch of humidity but not especially muggy, low 60s for dewpoints. Friday night introduces drier air, and that lower humidity will allow temperatures to cool down to the upper 50s for low under mostly clear skies.

Looking into next weekend, conditions appear to be pleasant for outdoor activities. It will be partly cloudy both Saturday and Sunday, with mid 80s and dewpoints in the upper 50s (comfortable) for Saturday, and a little warmer and more humid Sunday, with highs in the upper 80s.

Graphics courtesy of the NOAA Climate Prediction Center.

Extended Outlook

Looking into early August, the large-scale pattern favors a ridge of heat over the Upper Midwest and Northeast, and that will result in unseasonably warm temperatures for what is climatologically the warmest part of Ithaca’s year. Precipitation is expected to run near to slightly below normal as the jet stream is displaced northward and Gulf moisture is relegated to the base of the ridge in the Deep South and Southern Appalachians. This a recipe for a very thirsty environment, and honestly not good news given the spreading and deepening drought conditions across the region.

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