ITHACA, N.Y. — To close out meteorological fall, it will be seasonably chilly and unsettled. While no major weather events are in this week’s forecast, grey skies with rain and wet snow look likely for most of the week, though with little to no new accumulation.
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A weak shortwave (pulse of atmospheric instability) is passing through Upstate New York today, and the results are fairly typical for late November; a few light snow showers with little accumulation (as my mother likes to call it, “movie snow”), and overcast grey skies that are such a prevalent feature in one of the cloudiest regions of the continental United States.
As the shortwave moves through the Finger Lakes heading eastward, these snow showers will persist through the overnight and into the early hours of your Monday morning commute. Overall, don’t expect more than an inch of new accumulation in Ithaca, with localized areas of perhaps two inches if well-exposed to the west-northwest where some favorite winds allow lake enhancement. It’s enough to brush off the car and make the roads slick, but that’s about it. Mostly cloudy to overcast skies will prevent temperatures from falling back much, from today’s highs in the mid 30s to about the upper 20s for lows.
Monday shows some improvement as high pressure briefly builds in from the southwest. However, the winds will pick up and be breezy out of the northwest behind that shortwave, which will prevent any warming from that more stable airmass. Mostly cloudy skies will become partly cloudy by afternoon, with highs in the mid 30s and a wind chill in the mid 20s. Winds will calm down Monday night and clouds will increase as the lake effect bands move closer to Tompkins County, but it should remain dry. Expect a quiet night with lows in the mid 20s.
A trough will swing through Tuesday afternoon, part of a Canadian clipper low passing to the north. It will be an unsettled, overcast day, with some light snow and rain showers, but no significant accumulation is expected. Highs will be in the upper 30s as the winds pick up from the south ahead of the trough. Winds will be out of the west Tuesday night, with a few isolated snow showers, mostly cloudy skies, and lows around 30°F.
Wednesday will offer some brief improvement with a high out of the south. It will be dry with partly to mostly cloudy skies and light winds out of the southwest, allowing highs to climb into the lower 40s. The next system begins to move into the region Wednesday night into Thursday morning, though with thick cloud cover and warm air advection ahead of the low (recall air circulates counterclockwise around low pressure systems, so ahead and south of a low’s center is the “warm sector”), temperatures will still be in the mid and upper 30s by the time it arrives, meaning it will largely be a rain event by daybreak Thursday morning.
Thursday looks to be the warmest day of the week, albeit a wet day. The low will swing by to the north, reinforced by a secondary low, and these will result in persistent rain showers during the day Thursday, with overcast skies and highs in the upper 40s. The cold front will swing through after midnight Thursday, but by the then the bulk of the precipitation will be well to the east. Expect scattered rain showers to give way to a few isolated snow showers, with overnight lows in the mid 30s.
Friday will see a renewed flow of cold air out of the northwest, with some potential lake effect rain or snow showers during the day, especially north of Ithaca. It will be mostly cloudy with highs around 40°F. Friday night will be mostly cloudy with a chance for some lake effect snow showers mostly to the north of Ithaca, and lows in the upper 20s.
Looking ahead into next weekend, it will be unsettled as another Alberta clipper passes north of Tompkins County, but it will lack moisture and not be much of a hassle. Expect a chance of rain and snow showers both days, with partly to mostly cloudy skies and highs in the low 40s, and a chance for some light snow showers overnight Saturday with lows in the mid 20s.
Looking into the second week of December, the medium-range is favorable to a broad ridge in the jet stream with the maximum amplitude over the Great Plains states, the only cooler-than-normal region being further upstream of the ridge in Alaska. The models do suggest that systems will travel around the edge of the ridge and slide through the Northeast and New England, resulting in not only warmer-than-normal but also wetter-than-normal conditions for the period, and depending on timing these could be significant snow events. It’s too far out to see if this year’s Christmas will be white (right now the initial prognosis is less likely than normal), but we’ll keep you posted on any potential snowstorms should they show up with consistency in the forecasts.