ITHACA, N.Y. — If you haven’t stocked up on rock salt or your de-icer/friction provider of choice, Monday morning would be a good time to do so, ahead of a potential wintry mix that could introduce some sleet and some freezing rain into parts of Tompkins County. Beyond that, a brief warmup for Tuesday tapers back to cold and quiet conditions for the remainder of the week.
Taking a look at the climatological wrap-up for the month of December 2018, at 30.5 °F the month ended up being just a notch above average with an anomaly of +2.2 °F, and with 2.19″ of precipitation (liquid and liquid equivalent), it ended up a touch on the dry side at well, a bit below the December average of 2.46″. Those modestly warm and dry conditions translated to a lackluster amount of snow for the month, with 6.4″ recorded at the Northeast Regional Climate Center / Cornell weather station off of Game Farm Road in Dryden, less than half of the typical amount of 13.4″. Thanks to the heavy snows in November, however, we’re still running above average for the winter season.
Looking at 2018 as a whole, the annual average temperature clocked in at 46.6 °F, just a smidgen below (-0.4 °F) the annual average, and total precipitation came in at 41.66″, about six inches above the annual average of 35.67″. So long story short, 2018, was a wet year in Ithaca’s climate record, with generally average temperatures.
Looking at the week ahead, the same descriptors look to be in play – wetter than normal and perhaps a touch on the cool side, but nothing extreme expected for this second week of 2019.
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At the moment, the dominant weather feature is a strong are of high pressure situated over Southern Canada, which has been driving brisk northwest winds over Ontario and the Finger Lakes. This passage of seasonably cold air over the ice-limited waters of Ontario has allowed the lake effect to fire up somewhat, but a lack of moisture in the air has limited the lake effect to just scattered light snow showers across the region. As the winds slacken, the instability should decrease and the snow showers will taper off. Sunday night will see generally dry conditions and decreasing clouds, with a low in the mid teens in Ithaca proper, to perhaps ten above in the more rural areas.
Monday will start off quiet, with partly cloudy skies and high clouds giving way to a greyer, thicker cloudmass ahead of the next storm system approaching from the west. Winds will shift to the southeast by the afternoon hours as the low pressure area approaches, and temperatures will climb to about 30 °F by sunset, and hold steady or even creep upward through the evening as weak warm front pushes through. It’s looking like there are two primary periods of precipitation with this storm. The first in the late afternoon with the warm front, 3-5 PM. Temperatures should be cold enough at first for a quick light snow (a coating to half an inch) transitioning to sleet, but freezing rain is possible during the early evening, so use caution on your evening commute. No advisories have been issued yet, but with only moderate confidence in the forecast models, there is potential for an advisory to be issued in a later update, so keep an eye out for weather updates.
Monday late evening will be relatively quiet as a dry slot passes overhead, but a decaying frontal boundary will shamble through from about 11 PM through 2 AM as the low passes well to the northwest. This too looks likely to a wintry mix, and with temperatures hovering around 32, sleet and freezing rain will make travel potentially hazardous during the overnight hours. The precipitation will wind down and temperatures will warm into the mid 30s by daybreak, so the Tuesday morning commute should be manageable. New snowfall accumulations will be less than an inch, with a possible thin glaze of ice.
Tuesday itself will be cloudy and on the warm side for January, with highs in the mid 40s. Round two of the storm system will sweep in for Tuesday evening, as energy from the Canadian low gets transferred to a strengthening low passing over upstate New York and into northern New England. A cold front on the backside of this low will usher in colder air and a transition from rain to snow showers. Temperatures will slip back to about 32 °F by daybreak Wednesday, with a coating to perhaps half an inch of snow.
Wednesday will be cloudy and seasonably cold, with a northwest breeze and scattered snow showers throughout the day. Highs will be in the mid 30s, and new snowfall amounts will generally be in the half inch to one inch range. Wednesday night will be cloudy with a few lingering snow showers and lows in the mid 20s.
Conditions should dry out a bit Thursday as high pressure begins to build in again, and more northerly winds bring in drier if colder air into the Southern Tier. Highs will be in the upper 20s with mostly cloudy skies. Thursday night will be will be cold and quiet, with mostly cloudy skies, a few isolated snow showers, and lows in the mid to upper teens, perhaps single digits on the more exposed hilltops.
With high pressure in place, Friday will also be cold and quiet, with mostly cloudy skies and a high in the mid 20s. Friday night will be dry, with mostly cloudy skies and a low in the upper teens. The weekend is looking a bit warmer but with a renewed threat of snow showers with a weak atmospheric disturbance nudging into the region on a weak ridge in the jet stream. Highs will be around 30 °F Saturday and in the low 30s Sunday, with lows in the low 20s.
Also, a quick word of thanks to the hardworking staff of the National Weather Service, who are still carrying out their forecasting and analysis duties even with the uncertainty and difficulties created by the government shutdown.
Looking into the middle of the month, it’s looking like a pronounced ridge will set itself up over the Great Plains, but most of the ridge will be focused from the Central United States westward, with a sharp trough over the eastern seaboard and New England. That means temperatures will likely be a bit colder than normal for Ithaca and Tompkins County. On the bright side, it also appears that conditions will be drier than normal for the mid-month period. Some moderation to near-normal temperatures is expected heading into the second half of the month, but large-scale atmospheric teleconnections in the Pacific Ocean are contributing to an increased risk for cold air outbreaks in late January.