ITHACA, N.Y. — It’s looking like a mostly quiet week ahead as the most potent weather stays to our east. Apart from a cold front sweeping through Tuesday, high pressure will have control of our weather. It’ll be a seasonably cool if fair week ahead, though next weekend is looking like it has the potential to be stormy.

Precipitation, mean sea level pressure and 1000-500 mb thickness (temperature proxy) for 8 a.m. Tuesday morning. A cold front will sweep across the region, result in rainy conditions throughout the day. GFS Model output courtesy

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We’re finishing off the weekend with some relatively quiet conditions across the Southern Tier. The current disturbance, which has been enhanced by the remnants of Tropical Storm Nestor, is exiting the region and high pressure is building in its wake. The next real disturbance to impinge on our autumnal serenity will be a strong and large storm system brewing up over the Great Plains.

This storm will draw down a massive amount of cold air into the Mountain West, Great Plains and Mississippi River Valley as it deepens and draws frigid polar air into its counterclockwise circulation, but temperature-wise we in the Northeast are unlikely to see much in the way of change – like the previous storm that walloped the Great Plains a couple of weeks ago, this system will move north-northeast, and will be well to our north and much weaker by the time it reaches our longitude, easily deflected by the high-pressure building in for the second half of the week. However, the frontal boundary leading from its core will sweep across the Eastern U.S. like the spoke of a wheel, so we can expect a wet Tuesday in store for Tompkins County

Starting off, it’s a quiet Sunday night in Tompkins County, or at least it will be weather-wise. It will be partly cloudy overnight, with lows in the low 40s in the more urban areas and along the south end of Cayuga Lake, and upper 30s on the hills and especially east of Ithaca.

Monday will be a fairly pleasant as high-pressure shifts eastward and southerly flow is channeled into the region on its rear flank. Temperatures should climb into the mid-60s and even the upper 60s in a few spots, as we bask under partly sunny skies. Clouds will begin to cover more of the sky toward sunset, and by late evening it will be mostly cloudy to overcast. With the clouds holding in the day’s heat and southerly flow enhanced ahead of the frontal boundary, temperatures will only fall back to the low 50s for lows Monday night.

Tuesday will be a warm but wet fall day, probably enough to take many of the leaves off the changing trees. A strong south breeze will result in some gusty winds during the late morning through early afternoon, with gusts up to 30 MPH possible. Rain could arrive in areas west of Ithaca around sunrise, but generally, most of the county can expect rain by 10 a.m. Tuesday and can expect it to stick around for the whole day and into the evening before tapering off between 8 p.m. and midnight. This will be a light to moderate rain with some breaks, and overall we can expect about 0.5″ to 0.75″ of rain. With the cloudy skies, temperatures won’t be warming much, topping out in the low 60s. The clouds will move out during the overnight, and temperatures will be in the low to mid-40s by daybreak Wednesday.

Wednesday will be a little cooler, though not especially impressive since the high-pressure building in behind the front isn’t from the northwest as they often do here, but from the southwest, which will channel in air from the west-southwest in its clockwise circulation. Air over the Ohio River Valley isn’t that cold, so that means we aren’t going to be that cold. Plan for mostly sunny skies, and highs in the mid to upper 50s. Wednesday night will be rather chilly, with light winds and a few fair-weather clouds, temperatures will drop to the upper 30s to around 40° F.

Apart from the high to our south shifting further eastward Thursday, and maybe adding a modestly more southerly component to the wind, not much will change weather-wise. Highs will be around 60° F with partly cloudy skies Thursday. Thursday night will be partly cloudy with lows in the low 40s.

Friday will be seasonable with highs in the upper 50s under partly cloudy skies turning mostly cloudy as a plume of moisture rides up the backside of the high and into our region, bringing with it the potential for some showers. Friday night will be mostly cloudy with a chance for some light rain showers and a low in the around 40 °F.

Saturday and Sunday are looking seasonable if a bit unsettled, with mostly cloudy skies, scattered showers, and highs in the mid-50s during the day, and upper 30s for lows at night. We can’t discount the possibility for another layer in our usual cooler spots by daybreak Sunday morning. A developing storm to the southwest is still being resolved by the models, which are not in agreement, so the forecast for the weekend is bound to change as timings for rain and the amount of rain are better determined.

Graphic courtesy of the NOAA Climate Prediction Center.

Extended Outlook

Here’s an example of how the weather in one part of the world affects another.

In the Western Pacific, a powerful typhoon (what hurricanes are called in the Western Pacific) will be re-curving into the mid-latitudes, charging into the jet stream and undergoing an extratropical transition, meaning it’s no longer a tropical system, but a very strong mid-latitude storm.

As it does this, the effect on the jet stream is like a cannon-ball into a pool of water. The transitioning typhoon creates a huge ridge (which is partly why Alaska will be so warm), and the jet stream contorts into a huge trough downstream. Here, that means a large amount of polar air will be shunted down from northern Canada and into the Western and Central United States before Halloween, and eventually, this will overtake the East, if not quite as strong. By Halloween itself, much of the country could be shivering under abnormally cold temperatures, and the split between warm and cold air masses over the Southeast will serve as a conduit for storm systems as they develop and ride along its channel of instability.

The long story short is that we’ll want to keep an eye on the overall conditions, because if the timing is right, the cold air will be there to potentially allow for a form of precipitation other than rain, but it’s still too far out to tell at this point. Yes, we’ll be deploying the four-letter “S” word in the forecast soon enough, it’s just not clear if these large-scale conditions will result in that first instance.

Brian Crandall

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