ITHACA, N.Y. — According to observations at the Ithaca-Tompkins Regional Airport, the heat index reached as high as 106 °F at about 4 PM on Friday, and 101 °F on Saturday. It’s been brutal as summer days go in the land of gorges.
For those looking for a reprieve, however, your time is coming. A cold front passing through the Southern Tier tomorrow will send temperatures and dewpoints tumbling, though still fairly seasonable. We can expect a few pleasant dry days before the heat and humidity begin to creep back up in time for next weekend.
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The heat hasn’t been quite so bad this Sunday afternoon, though the heat index has been hanging around 90 °F for much of the day. The air in place is a touch cooler and somewhat less humid (a muggy dewpoint of 70 °F vs. a rare and extremely unpleasant 78 °F on Friday) as a low off the coast of Maine has created a northerly wind flow, drawing in more continental (drier) and somewhat cooler air, mixing with hotter and more humid air to the south.
An added benefit to this is that the drier air is more stable, so this evening and Sunday tonight should remain partly cloudy and rain-free except for one or two pop-up showers and thunderstorms south of Ithaca. Lows Sunday night will be in the mid 60s with a light northwest wind; for those who like the windows open when they sleep, we’ll call this a borderline case for comfort, as dewpoints will be in the low 60s overnight – a touch humid, not terrible.
Monday will be cooler with highs in the mid 70s, but still plenty humid. An approaching frontal trough associated with an area of low pressure over the Great Lakes will drive moist and unstable air into the region, with a jet streak aloft that will increase the instability of our corner of the atmosphere. However, it’s not looking like there will be much in the way of energy for thunderstorm development; so Monday is looking like rain, heavy at times, but no severe weather is anticipated. Expect about a quarter to half an inch of rain, starting around 7-10 AM in most areas (you’re on the later end of that range if east of Ithaca, earlier if west), with the majority falling between 11 AM and 6 PM as the front pushes through. After the frontal passage, scattered showers and thunderstorms will continue through the overnight, with mostly cloudy skies and lows in the low 60s.
Tuesday is looking pleasant thanks to high pressure building in behind the front from the Midwest. Apart from some lingering early morning showers east of Ithaca, it will be partly cloudy and comfortable humidity, with high temperatures in the upper 70s. Tuesday night will be cooler and comfortable, with partly cloudy skies turning mostly clear by the AM hours, and lows in the mid to upper 50s.
Wednesday will see the core of that high pressure area move closer to us, but otherwise more of the same weather-wise. Expect a few passing clouds, abundant sunshine, comfortable humidity and highs in the upper 70s. Wednesday night will see a few passing fair weather clouds and lows in the upper 50s.
The core of the high will be practically overhead for Thursday, so apart from a small increase in temperature and humidity with the loss of those clockwise northwest breezes, it will otherwise be sunny and seasonably warm. Highs will be in the low 80s. Lows Thursday night will be in the low 60s with mostly clear skies.
Friday will have Tompkins County on the backside of that high, and with its clockwise flow, that means we’ll be under the southerly winds, so a jump in temperature and humidity is anticipated. It won’t be as bad as this past week, but you’ll notice some stickiness to the air, with dewpoints in the mid to upper 60s. Actual temperatures for Friday will top out in the mid 80s with partly cloudy skies. Friday night will be mostly clear with lows in the mid 60s.
Looking ahead at next weekend, hazy, hot and humid appears to be the most likely outcome, as southerly flow brings temperatures into the upper 80s, with some mugginess (once again, upper 60s to 70 °F, so more typical summer heat vs. the exceptional conditions this past week), dry conditions Saturday, and dry early Sunday with pop-up showers and thunderstorms likely later in the day.
Chances for another heat wave are looking very good for the end of July and early August time frame, as a ridge of hot air over the eastern United States builds well into the northern latitudes, creating unseasonable heat and dryness for the Northeast through the first week of August. A similar dome of hot air will be in place over the desert Southwest as a persistent jet stream trough develops over the Pacific Northwest. Later in the medium-range period, the ridge is expected to shift a bit further eastward, which could allow for more frequent thunderstorm development as the dry spell shifts to a more seasonable pattern.