ITHACA,N.Y. — For those looking to enjoy a fireworks show as part of their Independence Day weekend festivities, you could hardly ask for a better night, especially after the cool and unsettled conditions of the past few days. However, the weather will become hotter and more unsettled for much of the week ahead, so while you won’t need an umbrella tonight, you’ll want to have it on hand from Tuesday through the rest of the week.
With June in the record books, from a climatological standpoint it will be remembered as a hot and rather rainy month. Temperature-wise, the average clocked in at 67.3°F, which is 2.7°F above normal. It may not seem like much, and compared to our winter seasonal variation it isn’t. However, with the angle of incoming sunlight being high in the sky this time of year in the Northern Hemisphere, the temperature gradient between the tropics and the polar latitudes is smaller, and that thermal difference is what drives the jet stream that usually controls the ridges and troughs that define hot and cold patterns (the recent heat dome over the Pacific Northwest was only possible because a number of conditions came together at the right time and location to create a summer jet stream ridge with maximum impact). That normally weaker summer jet stream generally results in less variable conditions, so temperatures aren’t as likely to stray too far from the climatological average.
With that noted, 67.3°F was 19th warmest in Ithaca’s 129 years of June temperature records, and the warmest June since 2008. Regionally, June 2021 was the hottest June on record for three of the 35 first-order weather stations (Portland, Maine, Caribou, Maine, and Boston). For 26 other stations, it was in the top 20 warmest. Seven stations, including Syracuse and Rochester, set their warmest overnight low for June, at 78°F and 75°F respectively on the night of the 27th. So for those who like it hot, last month was a summer start they could appreciate.
On the precipitation side, 4.42″ were received at the Dryden Game Farm Road station, a little more than the usual of 3.98″, and 41st wettest. It wasn’t a washout overall, as 13 of the 30 days of the month recorded rain, and only eight days recorded more than 0.1″. Regionally, much of New England was parched, while it was a mixed bag for Upstate New York and the Mid-Atlantic depending on where moisture-heavy pop-up thunderstorms rolled through during the month. 28 of the first-order weather stations were drier than normal, (with six hosting a top 20 driest June), one was exactly average (Newark), and six were wetter than normal (with two, Syracuse and Huntington, West Virginia, recording a top 20 wettest June).
July is off to a cool start thanks to a cutoff low that slowly spun its way across the Northeast over the past few days. Now off in Atlantic Canada, high pressure from the west has been moving into the region, and will usher in another heatwave as we head into the start of the week.
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Skies have started to clear out in earnest with the entrance of an area of high pressure now extending from the Mississippi River Valley into the Northeast. For your fireworks viewing this evening, the weather should be nothing short of ideal, with nearly clear skies and temperatures drifting back from the lower 70s into the upper 60s with calm winds and a comfortable dewpoint in the upper 50s. Overnight tonight will be meteorologically quiet, with a few passing clouds and lows in the upper 50s.
As the northern lobe of the high pressure area shifts eastward Monday, temperatures will climb substantially, with moist, warm southwesterly flow on the rear flank of its clockwise circulation. This will also bring the dewpoint up during the day, and it will feel rather muggy by the evening hours as temperatures top out in the upper 80s in Ithaca and mid 80s in the higher elevations. While there will be increasing clouds during the day, the atmosphere will not yet be unstable enough to support convection like pop-up thunderstorms. Monday night will be humid and partly cloudy, with an isolated shower or two to the north as part of a weak Canadian short wave (pulse of instability), and with lows around 70°F.
Tuesday will be even hotter and more humid as a frontal boundary extending from a Canadian low pressure system begins to press on the high from the northwest; with its counterclockwise flow, that will enhance the southerly flow ahead of it and on the backside of the high, and it will also create more unstable conditions. Winds will be breezy out of the south and west as showers and thunderstorms develop and move eastward across the Southern Tier during the afternoon and evening hours. High temperatures will be in the low 90s, and the heat index will be in the mid to upper 90s, so use caution if you’ll be outdoors for an extended period, and try to stay cool and hydrated whenever possible. Showers and thunderstorms will wind down after sunset, leaving partly cloudy skies and a humid low in the upper 60s.
Wednesday will be another unsettled day as another storm system begins to push into the Great Lakes. Afternoon and evening showers and thunderstorms are likely as clouds increase, with mostly cloudy skies in the PM hours and highs in the upper 80s. Rain showers will continue as the system approaches Wednesday night into Thursday morning, with mostly cloudy skies and lows in the mid 60s.
Thursday is looking like a grey, rainy and occasionally stormy day as the storm system and its cold front move eastward across the Southern Tier, though nothing severe is expected. Highs will be near 80°F. The showers should taper off after midnight as the system continues to move east Thursday night, with mostly cloudy skies and lows in the lower 60s.
The upper-level portion of this storm system will be slower to move out, and so a few showers are still possible Friday morning, though most areas will remain dry with partly cloudy skies. A second frontal boundary over the Great Lakes will usher in more showers late in the day, though far enough away that the impact Friday will be limited. Highs will be in the low 80s. Friday night will see the chance for showers increase with the next trough approaching, and a low in the low 60s.
The weekend will be unsettled as that next frontal trough moves across the region. Expect partly cloudy skies intermixed with scattered showers and thunderstorms and rather muggy conditions. Highs will be in the mid 80s Saturday and Sunday, with overnight lows in the mid 60s.
Looking into the middle of the month, the large-scale weather patterns being picked up in the medium-range forecast models suggests a continued hot and dry air mass beneath the jet stream ridge in the Western United States, though the worst of the next heat dome will be to the south and west of Seattle and Portland. Over the central United States, Mississippi River Valley and Depp South will be a pronounced trough with cooler and largely wetter than normal conditions. As for us here in the Northeast, wetter than normal conditions are expected to continue, but we’ll be close enough to the next downstream jet stream ridge that it will keep temperatures near-normal (i.e. upper 70s-low 80s for highs) during the middle of July.