ITHACA, N.Y. — There’s no way of sugarcoating it. It’s stifling outside, and Tompkins County will have to sweat it out for another day or so before gradual relief works into the region. It’ll give the stores time to replenish their stocks of ice pops and fans.

A Heat Advisory is in effect from 11am today through 8pm Monday for the Finger Lakes, Southern Tier and Mohawk Valley. The best chance for afternoon T-Storms will be across NEPA and the Catskills. The main threat will be heavy downpours and localized flooding.

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A stagnant frontal boundary lingers over Northern New York; as part of a Canadian low, it had tried to push through Upstate Thursday into Friday, but lacked the momentum and strength to dislodge a high pressure system over the Atlantic Ocean, and in fact it actually retrograded back to the northwest. For the past few days, this frontal trough has served as a conduit for moisture around the edge of the high, and a channel for the hot air being pumped into the Great Lakes and Midwest on the rear flank of the high.

The long story short is that the frontal trough is ushering tons of very hot, moist air into the region, and it able to maintain atmospheric moisture via instability showers and thunderstorms fed by the heat energy of that southwesterly air. These hot and oppressively humid conditions make the temperature feel dangerously high. Heat advisories have been abundant across New York State in the past several days; Heat Advisories remain in effect through tomorrow evening.

For the remainder of your Sunday, it will be unsettled. Showers and thunderstorms will continue to fire off, primarily south and east of Ithaca, with partly to mostly skies and temperatures in the low to mid 90s, which with dewpoints in the downright tropical low 70s, will make it feel like it’s around 100 degrees. The high dewpoint also means little respite at night – moisture slows down the cooling of air, and the air temperature cannot go below the dewpoint. While the showers will shift down with the loss of daytime heating and clouds will decrease, it will remain humid Sunday night with lows around 70.

Monday will see at least one more day of the very hot and humid regime. A reinforcing cold front will sweep across the Great Lakes as part of a compact low, and that will finally shunt the sultry air mass eastward, but it will take time to get here. Expect hazy, hot and humid conditions to continue, with pop-up afternoon showers and thunderstorms, oppressive mugginess and increasing clouds with highs in the low 90s, that will feel more like the upper 90s. New rainfall amounts will generally be less than 0.1″. Monday night will be mostly cloudy with scattered showers and non-severe thunderstorms ahead of the low with lows around 70.

The cold front looks to cross Tompkins County during the mid/late morning hours Tuesday. This will come through with a widespread area of rain and slow down as it works to dislodge the high, so expect a wet, near-overcast morning with light to moderate rain with a few rumbles of thunder, with decreasing showers and clouds late in the day. The humidity will persist, but with highs in the mid 80s, Heat Advisories appear unlikely at this time. New rainfall amounts will be between 0.1 and 0.25″. Tuesday night will see a few lingering showers with partly cloudy skies and lows in the low to mid 60s.

Wednesday will still be on the warm side of normal, and rather humid, though not as sultry as the past few days. With high pressure coming in from the Great Lakes, expect a few weak pop-ups showers and partly cloudy skies with highs in the mid 80s. New rainfall amounts, if any, will be less than 0.1″. Wednesday night will host mostly clear skies with lows in the low 60s.

We can’t rule out an isolated shower or two Thursday, stirred up by a storm system passing to the north. As the next cold front crosses later Thursday, there isn’t much moisture available to it and it’s not that strong. All it’s likely to do is increasing the cloud cover, which will on the balance remain more sun than cloud anyway. Highs will be in the low 80s. Thursday night will be genuinely comfortable with a light north breeze and mostly clear skies allowing for a low in the upper 50s.

Friday will be a pleasant as drier air flows into the region on a northwest breeze, part of an expansive, strong high pressure system over the Midwest. The humidity will decrease during the day and it will be quite comfortable, with mostly sunny skies and highs in the upper 70s. Friday night will be mostly clear with lows in the low 50s; some overnight valley fog may develop in the usual suspect areas.

Next weekend is looking quite pleasant in the forecast runs. Expect mostly sunny skies Saturday with highs in the upper 70s, and partly cloudy Sunday with highs in the low 80s. Overnight lows will be in the mid to upper 50s.

Graphics courtesy of the NOAA Climate Prediction Center.

Extended Outlook

Looking into the second half of August, the large-scale pattern generally favors a pronounced ridge in the jet stream over the Western United States, with monsoonal flow off the Pacific to provide needed rain, and a more troughy pattern over the Eastern United States, with the next downstream ridge clipping New England. For Tompkins County, near to slightly-above normal temperatures with near-normal precipitation amounts are expected.

Brian Crandall

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