ITHACA, N.Y. — It feels more like September than November out there, as record-breaking heat caps off an extended spell of warm temperatures in Upstate New York. That will recede to values closer to normal as a cold front pushes in Monday night, but a second if briefer warm spell will provide mild temperatures late in the week.
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High pressure over the Atlantic Ocean is maintaining its grip over Tompkins County for the time being, but its regime is challenged by the approaching cold front boundary of a Canadian low. The high has been difficult to dislodge, and so the front is approaching at a very slow pace. The counterclockwise flow around the low and the clockwise flow of the high have worked in tandem to produce strong southerly breezes this weekend that have resulted in record high temperatures in many part of Upstate New York.
Temperatures have already hit 75°F at the airport (and a rather humid 75 at that, with dewpoints in the low 60s). With more sun breaking in through the clouds, chances are pretty high for another record high today, as Ithaca/Tompkins eke out another couple of degrees on the thermometer before the sun gets low and daytime heating is lost. The high dewpoint will result in another mild overnight, with temperatures falling back to the low 50s with a few light to moderate rain showers early, a possible weak thunderstorm or two, and decreasing clouds towards morning.
Monday will be the last of the near-record warm days, as the cold front moves through during the late morning hours. The air behind the front is very dry, so it will be a brilliantly sunny days, but also a breezy day as winds pick up from the northwest, with 20-25 MPH gusts by the afternoon. Highs will make it into the low to mid 60s, on the warmer side of that if the front is later and/or the winds are lighter. That drier air will allow for a steady cooling Monday night as high pressure builds in from the northwest. Expect mostly clear skies Monday night and lows in the upper 30s.
Heading into Election Day, the weather will absolutely not be your excuse to skip the polling place this year. Skies will be mostly sunny with highs in the low 50s. Tuesday night will be cold with a few passing clouds and lows in the upper 20s.
Wednesday will be somewhat warmer as the high slides to the southeast into New England, placing Tompkins County on the warmer rear/west flank of its clockwise flow. It will be sunny with highs in the upper 50s. Wednesday night will be mostly clear and milder (perhaps less cold is better phrasing?), with lows around 40.
High pressure remains in control Thursday, as a broad and powerful storm system develops over the Midwest. While it brings blizzard conditions to the Northern Plains, we’ll be in its placid warm sector, which will further boost temperatures. Thursday will be mostly sunny with highs in the upper 60s. Thursday night will see increasing clouds as the system begins to head east-northeast, with lows in the upper 40s.
The forecast from here on gets a little tricky. Models show a tropical storm developing and are suggesting this will make landfall, possibly as a hurricane, on the Atlantic coast of Florida late this week (this system is likely to be named “Nicole”, though if a developing low in the North Atlantic gets named first, that will be Nicole and the Florida system will be named “Owen”). The storm then gets picked up by the cold front low pressure system from the Midwest and pulled up along the Atlantic Coast, which makes for a very complex forecast. With this in mind, the forecast comes with a higher degree of uncertainty than usual.
Friday, it’s reasonable to say that during the day will be mostly cloudy with some showers ahead of the front and highs in the mid to upper 60s. Early Friday night has rain possible with lows in the low to mid 40s.
Beyond that, the amount of rain and the temperatures are very difficult to predict – the tropical moisture will have great influence on rainfall and the surge of subtropical air will impact temperatures, all while the cold front pushes eastward. The consensus is for an unsettled Saturday in the low 50s, and the surge of cold air behind the front will likely keep highs in the lower 40s Sunday, though Tompkins will be far enough from the front at that point that it should be a dry, partly cloudy day.
It’s not often that practically the entire Lower 48 is expected to have below-normal temperatures, but here we are. The large storm system later this week and a low wave-number pattern in the jet stream (which means it was a long wavelength) will result in a trough over much of the continental United States, while Alaska, further upstream in the ridge, will be above normal. For what it’s worth, I’m seeing temperatures about ten degrees below normal for highs at its max, moderating later in the period. It won’t be like that blistering cold Thanksgiving a few years back. Precipitation will be slightly below normal for the period.