ITHACA, N.Y. — It’s getting pumpkin spicy out there. A persistent trough over the Great Lakes will result in some unsettled and cooler than normal conditions to close out September. But for those of you who adore the changing colors and crisper air of fall, you’ll be in your element.

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The dominant feature in the local weather for the next few days will be a deep, slow-moving low pressure storm system over the Great Lakes. With a very pronounced and strong ridge over the Great Plains, there’s nothing to really push this trough and associated low forward, so it’s going to linger over the Great Lakes and Northeast for a few days before slowly moving off to the northeast.

As a result, temperatures over the next few days are likely to be a little below average, though not icy cold – imagine the climatology is two to three weeks ahead of schedule, and you’ve got the idea. There will also be frequent cloudiness and occasional showers over the next few days, though overall rainfall amounts will be light.

As an aside, Tropical Storm Ian’s trajectory is directly impacted by this trough. The stronger and/or more to the east it is, the sooner Ian, likely to become a major hurricane, takes a turn to the northeast and into Florida’s west coast, drawn in by the trough. A weaker or more westerly trough will pull it further up into the Gulf of Mexico and into the Florida Panhandle. In either case, if you have a vacation home or family down there, keep an eye on it; someone’s getting walloped later this week, we just aren’t sure who yet.

For the rest of your Sunday, expect periods of showers and a few thunderstorms as the low’s warm front cross the region. With that rain and with cloudy skies overhead, highs will only top out in the low 60s even with the light southwest wind ahead of the low pressure system’s core. New rainfall amounts today will be in the 0.25-0.50″ range. Tonight will see thunderstorms ending, and showers becoming more sporadic, though a few will cross Tompkins County during the overnight hours. Skies will be mostly cloudy with lows in the low 50s.

The cold frontal boundary will still be to the west of Ithaca on Monday. This will keep Tompkins in the warm sector through the day, though conditions will continued to be unsettled. Expect some scattered light rain showers and a few isolated thunderstorms, but less than 0.1″ of new rainfall, with mostly cloudy skies and highs in the upper 60s. As showers lose the energy of daytime heating, Monday night will see showers ending, leaving partly cloudy skies and lows around 50.

Current models show the frontal trough crossing anytime from Tuesday evening to just before sunrise Wednesday – once again, a mild nuisance for us, but a nightmare for hurricane forecasters. It does look like a little more moisture and instability will be present Tuesday just ahead of the front, so the chances for scattered showers and thunderstorms will be greater; also, it will be cloudier, which will limit the rise in temperature. Expect mostly cloudy skies with periods of showers or a rumble of thunder, with highs in the low to mid 60s. New rainfall amounts will be in the 0.10-0.25″ range. Tuesday night will see mostly cloudy skies and a few showers as the front passes, with lows in the upper 40s.

Even with the frontal passage, Wednesday will remain unsettled as we enter the cold sector, and those northerly winds pass over Lake Ontario, resulting in lake-enhanced showers. Plan for some light rain showers throughout the day with mostly cloudy skies and highs in the upper 50s. Wednesday night will see a a few persistent showers with mostly cloudy skies and lows in the mid 40s.

Heading into Thursday, a large area of high pressure begins to build in from the northwest. With a strong northwest breeze, it will be a cool day, with partly cloudy skies and highs in the upper 50s. The wind settles overnight, and mostly clear skies will allow for a chilly night and some likely frost on the hilltops. Lows will be in the upper 30s. For what it’s worth, this high will keep the remnants of Ian from penetrating into the Northeast.

Friday will be a little warmer with high pressure overhead. Skies will be partly cloudy with highs in the low 60s. The high shifts a little eastward Friday night, allowing for weak southerly flow, and so lows won’t be as cold, mostly clear but in the lower 40s.

Looking into next weekend, it appears that it will be seasonably mild and dry as the remnants of Ian pass to the south. Highs will be in the lower to mid 60s with partly to mostly cloudy skies. Overnight lows will be in the 40s.

Graphics courtesy of the NOAA Climate Prediction Center.

Extended Outlook

Heading into the second week of October, the extended-range favors continuation of the pronounced ridge over the Central United States, but an eastward shift will result in a moderation in temperatures in the Northeast, from below-normal to near-normal. Locally, precipitation is expected to be near-normal for the period.

Brian Crandall

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