ITHACA, N.Y. — For those of you cooking in this latest heat wave, there’s some good news and bad news. The good news is, the temperatures we’re seeing today – into the mid and upper 90s across much of the Northeast – will drop off as a Canadian trough presses against the jet stream ridge “heat dome” that has baked much of the eastern half of the country this month. The bad news is that that the air behind isn’t really cool, it’s just less hot, with temperatures topping out in the mid and upper 80s by late in the week.

Your Weekly Weather

With average temperatures pushing about 4°F above normal, it’s to-date the warmest July recorded in Ithaca since 1955. Before that time there’s about a dozen or so instances of warmer average monthly temperatures, but they also come with the big caveat that in those days the weather station used to be on Cornell’s Ag Quad, which even then was a more urbanized setting prone to the urban heat island effect. Once the station was moved further out into Dryden with only small groves and farm fields as neighbors, the average temperature dropped off accordingly, though in recent years it’s started to approach those old Ag Quad highs again.

Across the Northeast, the story is similar. At the first-tier sites (fully manned 24/7 and quality-controlled), Buffalo’s running for its hottest July on record, Syracuse its second-warmest, and Albany its third-warmest. With few breaks, we have been cooking the past couple weeks, and this latest heat wave is the most potent volley of heat yet.

At present, a lobe of the heat dome sits over the Northeast, and the temperatures and humidity are nothing short of stifling. With highs expected to reach about 98°F later this afternoon, and dewpoints around 70°F, the heat index will feel like 105. A heat advisory remains in effect until 8 PM. Just in case you need it, here’s the county’s tips and advice for coping with high heat, and identifying signs of heat exhaustion and heat stroke.

There is some risk of severe weather this evening as a squall line of thunderstorms presses into the Eastern Great Lakes ahead of an upper-level trough moving eastward across Canada. With the heat of the day approaching its maximum and providing lots of energy, and with the high humidity creating a more unstable atmosphere, this is something that needs to be watched, especially as it approaches Tompkins County in the 5-7 PM time frame – heavy downpours, small hail, and wind damage would be the primary risks. After sunset, the loss of diurnal heating will call these storms to fall apart.

Sunday night will be unsettled as the frontal trough approaches, setting off showers and thunderstorms during the overnight hours. There’s a chance that the storms could organize into another squall line, in which case there will be damage risks from gusty straight-line winds. Generally, though, the storms should remain cellular and scattered, with mostly cloudy skies between the storms and muggy lows in the low 70s.

Monday will be quieter and a little cooler as the cold front passes and winds turn from the southwest to the west by sunrise. With a modestly cooler and more stable airmass filtering in as part of an area of high pressure, it will be a more pleasant day than Sunday. Temperatures will top out around 90°F with partly cloudy skies, and the dewpoints will be in the mid 60s – humid, but not as bad as the previous few days. Monday night will see mostly clear skies and a low in the low 60s.

Tuesday should be another quiet as the high pressure shifts eastward. It will be a warm, sunny, and slightly humid day with highs in the mid 80s. Tuesday night will see a short wave (pulse of instability) enter the Southern Tier ahead of an unstable air mass supported by a low moving eastward across Canada, and a second developing over the Mid-Atlantic coast. Tuesday night will start off dry and partly cloudy, but showers and near-overcast conditions will prevail by morning. Lows will be in the mid 60s.

Wednesday will be a warm but stormy day, as the shortwave and a frontal trough to the west will make for a large but very unstable air mass overhead. It will be cloudy and muggy, with frequent batches of showers and thunderstorms throughout the day. Highs will be in the low to mid 80s. This activity will decrease somewhat Wednesday night with the loss of daytime heating, leaving partly cloudy skies and a few isolated showers overnights, with lows bottoming out into the upper 60s.

The trough should move through Tompkins County early Thursday, and that will settle the atmosphere down, but otherwise, it’s not much of a change in overall conditions – hot and humid will prevail as they have throughout much of the month. Thursday will be partly sunny with a few isolated showers and thunderstorms, humid with highs in the upper 80s. Thursday night will be partly cloudy with lows in the low 60s.

Friday should be more pleasant as high pressure sinks southeastward from the western Great Lakes. The humidity will be lower, and skies will be mostly sunny with highs in the mid 80s. Friday night will host a few passing clouds, calm winds, and lows in the low 60s.

Looking ahead into the weekend, Saturday will see the high shift east, and in its southerly rear flow we can expect sunny skiws and highs in the upper 80s. Sunday is looking more unsettled as a trough drapes southward from Canada, and it’s looking like scattered showers and thunderstorms with highs in the mid 80s.

Graphics courtesy of the NOAA Climate Prediction Center.

Extended Outlook

For those hoping for a break from the heat, it won’t be coming this month. The “heat dome” ridge of hot air that shoved the jet stream well into Canada will persist at least into the start of August, though things could be a little more variable on the West Coast. Precipitation will run a little below normal early in the period, and a little above normal later. There’s a good chance quite a few weather stations in the Northeast will be reporting their highest monthly average temperatures if this pattern pans out.

Brian Crandall

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