ITHACA, N.Y. — This is one of those weeks where if you don’t like the weather, just wait a little bit and see what comes next. The winds will be whipping tonight as a potent storm system sweeps across the Great Lakes over the next couple of days, and temperatures and weather conditions will vary widely as we head through the week.
November was a little colder and drier than average, though neither of those figures were especially unusual. According to the Northeast Regional Climate, the average temperature of 37.3°F was 1.3°F below normal, and the precipitation total of 2.69″ was a little drier than the usual 2.94″ (and on the solid side of that measurement, snowfall was 3.7″, a little below the November normal of 4.6″).
Across the Northeast and Mid-Atlantic, only four of the 35 first-order weather stations were above normal for November – Newark, Syracuse, Buffalo and Scranton. A persistent trough to the west allowed for extended cooler-than-normal conditions across the Great Lakes and into the Deep South, and the further east (away) one was from that, the more mild they tended to be.
Meanwhile, on the propitiation side, apart from a northeastward track along the eastern Great Lakes, most areas were below normal on precipitation, with 32 of the 35 first-order weather stations reporting drier than normal Novembers (Erie, Syracuse and Burlington were the wetter ones).
For meteorological fall, however, 2021 will be on the wet and warm side. The September-October-November time period say top 20 warmest falls at 29 of 35 stations, and 24, or about two-thirds, had wetter than normal autumns. The full write-up is on the NRCC’s website here.
December has started off on a warm note, if also cloudy and wet. It’s a fairly well-mixed bag in the week ahead, with some seasonably cold days mixed in with some quick spurts of milder conditions, and multiple days with rain or snow showers, though nothing that looks likely to create havoc.
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The biggest issue facing Ithaca and Tompkins County at the moment is a wind advisory in effect from 10 PM tonight through 7 PM Monday evening. A brief bubble of high pressure is quickly moving east, and a developing storm system is strengthening as it cuts across the Great Lakes and into Ontario and Quebec. As that system strengthens and presses against the high, that is creating a tight pressure gradient, which drives up the winds aloft, and the atmospheric conditions are allowing that to mix down towards taxpaying surface residents.
The winds will continue to build over the course of this evening. Winds will be steady in the 15-20 MPH range with gusts around 35-40 MPH in Ithaca and closer to 45 MPH on the hilltops, particularly northwest of Ithaca, closer to the core of the low. These winds will be at their strongest from 12 AM – 3 AM, so before you go to bed tonight, make sure to secure any loose outdoor objects like Christmas decorations, or garbage cans, and try to avoid parking under trees, because no one wants to wake up to find a branch through their windshield. On the same note, use caution if you’ll be driving overnight tonight, just in case any large branches fall onto the roadways, and pay attention to high profile vehicles like tractor trailers, as they have less control in high wind situations. Some localized power outages are possible as well.
Other than the wind issue, it’ll be mostly cloudy with rain showers starting in the early AM hours. The sheer amount of mild air being forced into the region will actually raise temperatures through the night, from upper 30s now to upper 40s by sunrise. New rainfall amounts will be less than one-tenth of an inch, and it should be all-rain to start, given the vertical temperature profile.
It’ll be windy, wet and mild Monday. The rain showers will continue intermittently through Monday afternoon, changing briefly over to snow Monday night before winding down. Temperatures will top out in the mid 50s with cloudy skies and new rainfall amounts between one-tenth and one-quarter of an inch. Winds will gust to 25-35 MPH across the county, weaker than the overnight but still quite breezy. The cold front associated with the low will come through around sunset Monday, and temperatures will steadily fall back into the upper 20s by morning, with the winds slowly settling down over the course of the evening. New snowfall should be no more than a dusting to a thin coating.
High pressure builds in from the Ohio River Valley Tuesday, which will allow for a quieter, drier, and colder day. Highs will be in the mid 30s with a light northwest wind and partly to mostly cloudy skies. Tuesday night will be mostly cloudy and quiet, with calm winds, a few lake effect snow showers to the north, and lows in the low to mid 20s.
Wednesday is something of a question mark in that the models were initially showing snow light snowfall from the precipitation shield of a developing coastal low pressure storm system moving northeastward from the Carolinas towards Atlantic Canada, but have since backed off on the precipitation shield getting this far to the northwest. The best estimate right now is for a mostly cloudy to overcast day, with a few light snow showers producing no more than a new coating of snow, and highs in the mid 30s. Those showers pull away as the storm heads east, and overnight it will be mostly cloudy with lows in the lower 20s.
Thursday will be quieter thanks to high pressure over Quebec. It will be partly cloudy with highs in the mid 30s. A weak short wave (pulse of instability) is likely tp pass through Thursday night, but precipitation will be light, with mostly cloudy skies and lows in the upper 20s.
A jet stream ridge builds over the eastern United States Friday, the downstream effect of a strong storm system trough develops over the central part of the country, creating a pronounced trough. Like a jump rope snapped up and down, a powerful event will trigger inverse waves downstream, in this case the ridge. Friday will be dry and mostly cloudy with highs in the mid 40s.
Unfortunately, the low quickly begins to push northeastward, creating a mild but wet Saturday. Friday night will see a few rain or snow showers after midnight with lows in the upper 30s, while Saturday sees rain showers and makes it into the low to mid 50s before the cold front comes through and brings drier and cooler conditions for Sunday, with highs in the upper 30s and partly cloudy skies.
It’s not very often the Climate Prediction Center has to break out the maroon color over such a large swath of land. But the models are consistent on a large and powerful jet stream ridge in mid-December, resulting in warmer than normal conditions across much of the continental United States. The only below-normal areas are the Pacific Coast and Alaska. Concurrently, conditions are expected to be fairly dry, with below-normal precipitation expected. Early indications show a continued warm bubble into the second half of the month as well – not blazing, but upper 40s and 50s look plausible. Chances of a “White Christmas” aren’t looking great at the moment, but we’ll see how conditions look as we get closer to the holidays.