ITHACA, N.Y. — It will be a generally quiet week weather-wise, though there will be a few opportunities for some rainfall in the upcoming days. Some light rain is possible for Labor Day morning, Wednesday and Thursday evening, and some stronger thunderstorms are possible Wednesday, the result of a pair of Canadian lows sweeping frontal boundaries across the Southern Tier. But Tuesday and Friday should be mild and pleasant, and next weekend is looking dry and comfortable as well.
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Scattered showers and thunderstorms are moving across Upstate New York this afternoon ahead of a frontal boundary associated with an area low pressure moving eastward over Canada. While the atmospheric dynamics aren’t favorable for severe weather, rounds of showers and thunderstorms will continue during the day today, with the height of activity being in the 4-7 PM time frame when the most daytime heat energy will be in the air above. This activity will begin to wind down by sunset as skies begin to clear up, but most areas can expect one-tenth of an inch to one-quarter of an inch of new rainfall today. With the cloudy conditions, highs today will only make it into the mid 70s in Ithaca and low 70s in the outlying towns. Sunday night will be dry and fairly quiet with partly cloudy skies and lows in the upper 50s.
For your Labor Day Monday, the front will push through during the morning hours and bring another round of rain showers with it, but these should be light and sparing enough that they’re unlikely to put a damper on any outdoor plans. The air behind the front is fairly mild, so temperatures will actually be comparable to Sunday, even with the northwesterly flow. A few stray showers will last through the afternoon Monday, but most communities should expect partly cloudy and dry conditions with a breezy northwest wind during the afternoon and highs in the mid 70s. Monday night will be mostly clear and quiet with lows in the mid 50s.
Tuesday will be a warm and pleasant day as high pressure builds in from the Mid-Atlantic. This high will shut down the northwesterly flow and turn it to a weak southwesterly flow, which will allow the temperatures to perk up. Expect near clear skies Tuesday with highs around 80°F. An upper-level low pressure system moving from the Western Great Lakes northeastward into Canada will bring renewed chances for rain after sunset ahead of its passage, particularly after midnight, through new amounts will be light. Apart from the showers, it will be partly cloudy with lows in the mid 60s.
As that low passes to the north, Wednesday will be an unsettled day as another frontal boundary sweeps across the region, with a southwesterly breeze ahead of the low Wednesday and temperatures in the upper 70s for highs. Skies will be mostly cloudy with scattered rain showers throughout the day, and this will need to be watched for the potential development of strong thunderstorms. Wednesday night will see the showers and storms tapering off as the front passes, with partly cloudy, dry conditions and lows in the mid 50s.
The air mass behind this front is a little cooler, but temperatures will remain on the mild side for Thursday with partly cloudy skies and highs in the mid 70s. A weak shortwave (pulse of instability) passing around the low to the northeast will trigger a few light showers across the Southern Tier later Thursday, though any new rainfall amounts should be light. These showers will taper off as the shortwave moves eastward Thursday evening, with dry conditions overnight Thursday into Friday under partly cloudy skies and lows in the mid 50s.
High pressure from the mid-Atlantic will take a firmer hold Friday, hemmed in somewhat by Hurricane Larry to the east. Expect a few passing clouds and highs in the low and mid 70s. Friday night will be partly cloudy with a low in the mid 50s.
Looking into next weekend, the forecast models show there could be some passing showers Saturday night into Sunday with yet another Canadian low passing Ithaca/Tompkins to the north, but even if that pans out, it’s not looking to be a major event. Highs will be in the mid 70s during the day both Saturday and Sunday with partly cloudy skies, and upper 50s for lows overnight.
Looking out into mid-September, the medium-range weather pattern favors a large and strong jet stream ridge over the Great Plains and Midwest, results in hot air being brought poleward from lower latitudes and a widespread area of warmer than normal temperatures, of which Tompkins County will be on the periphery of. Near-normal to slightly drier than normal conditions are also expected as the ridge creates a large bubble of high pressure over the Mid-Atlantic and Southeastern United States.