ITHACA, N.Y. — The past few weeks have been rather messy from a meteorological standpoint, between multiple snow storms (from both coastal storms and lake effect bands in their wake) and bone-chilling temperatures. This week won’t be great by any measure, but compared to the first two-thirds of February it’ll be a welcome reprieve. High pressure will build in on the heels of a storm system passing through Monday, which should allow for the warmest temperatures we’ve seen since Christmas Eve, and generally quiet conditions for most of the week.
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It’s a quiet, cold yet sunny Sunday across Tompkins County now that the as the last tendrils of lake effect snow bands wither away under the dry, stable air of an Arctic high. Since high pressure systems have counterclockwise air flow and the core is to the east, we’re seeing a modest amount of warm air advection from the south, which counteracts some of the Arctic air and allows for a seasonably cold day with highs around 30°F.
Clouds will steadily build in late evening ahead of the next system, an area of low pressure over Iowa heading east-northeast. There is not a lot of moisture for this storm system to tap into and it’s not very strong, so major impacts are unlikely. The building cloud cover will provide some insulation overnight, with lows in the upper teens, and a few precursor flurries are possible but not accumulations are expected overnight.
Looking at Monday, most of the snow that falls will do so between 8 AM and 2 PM, and that’s not much – most of Tompkins County can expect 1-2″ of snow, and with an area of high pressure will be pushing in from the southwest right behind the storm system, and instead of the usual cold northwest winds behind a counterclockwise-circulating low pressure area, the low will be wrapping in milder air from the clockwise-flowing high to the southwest. In other words, it’s likely to transition over to rain during the afternoon as the low passes eastward. Winds will be gusty from the south during the late morning, but the high temperature in the upper 30s won’t occur until the late afternoon, when the wind slackens and begins to turn southwesterly as the milder air of the high wraps in. Skies will remain cloudy Monday night with a few lingering rain-turning-to-snow showers in the evening, with lows in the upper 20s.
Tuesday will be unsettled as a weak shortwave (pulse of instability) passes around the northern periphery of the high and across the Southern Tier. This will result in a new coating of snow after sunrise, but this will change over to a light rain by afternoon. Expect a fairly gray day with highs in the low 40s. Tuesday night will see some clearing as the shortwave moves eastward, with dry, mostly cloudy skies and a comparatively mild overnight low in the low 30s.
Wednesday will be a more pleasant as the high moves over the Deep South and takes a firmer grip of our local column of atmosphere. It will be a mild day with a light southerly winds and highs in the upper 40s in Ithaca and mid 40s in the outlying towns. A weak storm system will skirt by to the north Wednesday night, which will allow the cloud cover to persist and potentially enable a few rain or snow showers to cross the Southern Tier, though no significant impacts are expected. Lows will be around 30°F.
As the southern high shifts eastward, a new high pressure will take hold from the Midwest, and this will bring colder air in for Thursday, if still fairly stable and dry air. Plan for partly cloudy skies and highs in the mid 30s. Thursday night will be dry and partly cloudy with lows in the upper teens.
Friday will be more of the same as the high slowly shifts east. It will be partly cloudy with highs in the low to mid 30s. Friday night will be partly cloudy with lows in the upper teens.
As the high shifts east of Tompkins County for the weekend, temperatures should warm up in the southerly flow of its rear flank. A system may pass close enough Sunday to produce some rain or snow, but right now it looks a little too far to the east to be of much impact. More notable is a potentially significant storm system showing up in the American (GFS) and European (ECMWF) model runs that may develop and pass through early next week, but it’s too far out to make any firm predictions. Expect partly cloudy skies and highs in the low 40s Saturday, dry conditions and lows in the upper 20s Saturday night, and mostly cloudy with a chance for light rain or snow showers Sunday with highs in the mid to upper 40s as we close out the month.
Heading into the start of March, the large-scale pattern is favorable for a jet stream ridge and warmer than normal air in the eastern third of the continental United States, and a pronounced trough over the West Coast. This will allow dry polar air to intrude into the Mountain West and Great Plains, while for Ithaca and Tompkins County, the core of that ridge to the southeast will mean that the jet stream passes close to the Southern Tier (i.e. more passing storm systems) and in a position to tap into moisture from the Gulf of Mexico, resulting in elevated chances for precipitation. March is one or our most variable months, but the early indicators call for a modest warmer and wetter start than climatology. Very early indicators show a significant warm pattern developing later in March, but we’ll have to wait and see if those pan out in the shorter-range models.