ITHACA, N.Y. — It’s the time of the year for long evenings and light clothes. The drinks are cold, the fans are blowing, and the sunscreen is generously applied. The week will start off on the humid side, but with the passage of a slow-moving cold front Tuesday and Wednesday, the week will finish out sunny, warm, and a little less humid, perfect for making those summer memories.

Precipitation, mean sea level pressure and 1000-500 mb thickness (temperature proxy) for 8 AM Wednesday morning. A cold front will be pushing into the area from the west, resulting in rainy conditions for both Tuesday and Wednesday. GFS Model output courtesy tropicaltidbits.com.

Your Weekly Weather

Starting off this Sunday evening, the heat of the day and the unstable, moist atmosphere enhanced by a weak disturbance (shortwave) aloft have allowed some thunderstorms to fire off across the Southern Tier, with some of the convective (pop-up) cells being on the strong side and causing the National Weather Service in Binghamton to initiate severe thunderstorm warnings in several communities.

Looking at tonight and tomorrow, the region will be between a high pressure system to the east over the Atlantic Ocean, and a cold front associated with a Canadian low coming in from the west. The clockwise flow of the high and the counterclockwise circulation of the low will work in tandem to create a strong southerly wind, one that will bring in hot, humid air from the Southeastern U.S. In short, tomorrow will be a lot like today, maybe a tad warmer.

For tonight, the chance for thunderstorms will decrease as the heat of the day dissipates and the energy it injects into the atmosphere is no longer present to power storm development. Expect partly cloudy skies and a rather muggy night with lows in the upper 60s.

Heading into Monday, it will be on the sultry side, as temperatures quickly climb into the upper 80s, maybe a few 90 °F readings in the valleys. With oppressively high dewpoints in the low 70s, the heat index will feel more like the mid 90s, so be careful if outdoors, and keep an eye on neighbors who may not have easy access to air conditioning or cooler spaces. By noon, thunderstorms will begin to build up as that daytime heat powers up their development and another weak disturbance passes aloft, and the risk for thunderstorms, some of which could be on the strong side, will persist through the afternoon and early evening. Monday night will be warm and muggy with the front unlikely to make it in before daybreak. It will be partly cloudy, muggy, with lows in the upper 60s.

The front should be near Buffalo Tuesday morning, and slowly plodding eastward over the course of the day. It will be increasing cloudy as the day goes on, with the likelihood of rain showers or thunderstorms growing as the incoming front destabilizes the atmosphere ahead of it. It will be hot and humid, with highs in the upper 80s. The greatest likelihood for rain will be in the evening and the early overnight hours, but scattered rain showers and storms will continue through the night Tuesday, with some downpours likely given the humid air and slow movement of the cold front. It will be cloudy with lows in the upper 60s. Expect a quarter to half an inch of rain. The model soundings of the vertical layers of the atmopshere suggest storms Tuesday could be severe, so keep an eye out for warnings if you’ll be out and about during the day.

The front will finally push through Wednesday morning around mid-morning, but its slow motion means rain will linger through the day. 8 AM to 1 PM looks to have the strongest chances for rain, progressively winding down during the afternoon hours. Mostly cloudy skies will start to clear out during the PM hours, with mostly dry conditions across Tompkins County and partly cloudy skies by sunset. Highs will be in the low 80s. The last of the rain will clear out early Wednesday night, with partly cloudy skies and lows in the low 60s.

Thursday and Friday are looking pleasant as a high pressure system builds into the region from the northern Great Lakes. Thursday will see mostly sunny skies and a high in the low 80s, with a touch of humidity (low 60s for dewpoints) but not especially muggy. Thursday night will be dry and quiet, with partly cloudy skies and lows in the upper 50s.

Friday will be slightly warmer as the northwesterly wind peters out with the core of the high moving into the region, but generally it will remain pleasant and summery, with mostly sunny skies and a high in the mid 80s. Friday night will see just a few passing clouds and a low in the low 60s, not bad for you stargazers paying trips to the open house at Fuertes Observatory on Cornell’s campus.

Looking ahead towards the weekend, it’s looking nice for your outdoor activities as the high pressure system retains its grip on Tompkins County. Both Saturday and Sunday will be partly sunny with a high in the mid 80s. We can’t totally discount the possibility of an isolated thunderstorm or two, especially Sunday on the back side of the high, but by no means is anyone getting a washout, and in fact most places will stay dry through the weekend.

Graphic courtesy of the NOAA Climate Prediction Center.

Extended Outlook

A pattern change is likely in the cards for the second week of August. A trough in the jet stream is likely toe result in cooler conditions for the central and eastern United States, though not necessarily stormier – places at the bottom of the western edge of the trough (Kansas, Missouri) will see wetter than normal conditions, but the wide variety of storm tracks us expected to result in near-normal precipitation for Tompkins County. Meanwhile, upstream in the Pacific Northwest, a ridge will pump heat poleward, while the trough in the east causes hot air to be pent up over the southern edge of the country, resulting in warmer than normal conditions for Florida and South Texas.

Brian Crandall

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