ITHACA, N.Y. — Many folks, Voice staff included, like some warm breaks to make the winter cold snaps a little more bearable. No one expects both of those to happen within the same 36-hour span.

Last Week’s Recap

It was hard to miss the rapid drop in temperatures on Friday, as temperatures fell from 63°F at about noon on Friday the 12th, to -7°F (with -16°F windchill) by 10 PM Saturday night. Yes, you’re reading that right, the temperature swung 70 degrees in a day and a half. As the National Weather Service’s Binghamton office has noted, as the strong cold front passed through, many places in the Southern Tier dropped 15 or 20 degrees in one hour. Cornell’s Game Farm Road observation site dropped from 59.6°F at 4 PM, to 41.1°F at 5 PM last Friday. Along with that came rain, fog, freezing rain, sleet, and snow. Offhand, the the only one missing from the party was gruapel. Reported snowfall totals ranged from 5″ in East Ithaca to almost 9″ in Trumansburg.

For the sake of accuracy, the county airport only reported a high of 62 F. So from their perspective, the temperature swing was only 69 degrees.

Image courtesy NWS Binghamton.

As it became clear for many folks last week, the combination of sudden, remarkable warmth and 1.13″ of rain and melted-snow liquid equivalent made for a rather unpleasant situation, as ice jams were reported across the region and state. An eye-popping ice jam on the Ausable River south of Plattsburgh has been making its rounds on news channels and websites the past few days. Closer to home, many residents of Ithaca city’s Fall Creek neighborhood found water in their basements, and an ice jam created flooding on Madison Street and First Street in the adjacent Northside neighborhood.

Let’s just make clear what an ice jam is for the uninitiated. Ice jams (also called ice dams) happen when rapid warmth and rain create a sudden spike in melt-off – this overwhelms frozen rivers, and the water breaks up the ice through force, and by weakening it with its slightly warmer temperatures. Where rivers narrows or the slope flattens out, the ice chunks can accumulate and clog up a river, forming a natural dam, and flooding surrounding areas. The dam is also temporary, so when it gives way, that may also send a deluge of frigid water downstream. Fall Creek and Northside have low-lying areas that are susceptible to these build-ups and break-ups.

Your Weekly Forecast

In the past couple of days, it has been relatively quiet, if bitterly cold. This morning, most folks are dealing with a fresh, light coat of snow, part of an area or low pressure passing through from the Great Lakes. With counterclockwise light southerly winds ahead of the low bringing in milder air, temperatures actually rose a little bit during the night to the low and mid 20s.

This system will combine with a coastal low pressure center to create a much stronger storm from Albany eastward. However, the latest model runs have noted an increased moisture content as well as  jet stream flow conducive for lifting that moist air and wringing it out as snow. As a result, expected snowfalls have increased to 3-4″ for most of Tompkins County through tonight and tomorrow morning.

For today, expect cloudy skies with snow showers and the occasional squall. These are most likely in the afternoon and will taper off through the evening. Highs will be in the upper 20s to 30°F. Tuesday night, the clouds will break up a bit, but it will still be mostly cloudy, with temperatures dropping to low to mid teens as cold air comes in from the northwest on the back side of a weak cold front passing through overnight, the tail end of that Great Lakes clipper low.

Precipitation, mean sea level pressure and 1000-500 mb thickness (temperature proxy) for 7 AM Wednesday morning. Cold air will move in from the northwest as a low pressure center moves eastward and merges with a coastal storm. GFS Model output courtesy tropicaltidbits.com.

It’ll be a brisk but quiet Wednesday as winds remain out of the northwest – nothing gusty, but highs will only be in the upper teens to about 20°F in our urban areas. A few folks well to the north of Ithaca may see a stray lake effect snow band, but don’t expect anything more than a coating. As the winds start to shift again Wednesday night, they’ll be west-southwest, limiting overnight lows to the low teens under partly cloudy skies.

Thursday starts a warming trend, as a ridge in the jet stream slowly builds while arctic air stays locked up in Canada. Expect partly cloudy skies and temperatures in the upper 20s, and lows Thursday night near 20. Friday will break freezing in most areas, with partly cloudy skies. Mid 30s in Ithaca, near 32°F elsewhere. Friday night will be partly cloudy with lows in the mid and upper 20s.

Image courtesy of the NOAA Climate Prediction Center.

Extended Outlook

The weekend looks more appealing. In the extended outlook, we’re seeing a substantial warm-up as the jet stream ridge builds and persists over the Northeast U.S. That will pump in lots of mild air, and perhaps Gulf of Mexico moisture to beef up rain accumulations next week.

Saturday is looking to make it into the low and mid 40s for much of Tompkins County with sunny skies, and Sunday is looking to be upper 40s to near 50 with mostly cloudy but dry conditions. Next Monday, many places will break the 50°F mark, although it’s looking like rain will move in by then. It will be downright mild, but with the rain and warmth, it will be necessary to watch out for more ice jams.

Beyond that, it’s looking really, really likely temperatures will be above normal for the last third of the month (the Climate Prediction Center never uses 90% probability unless they expect truly major and prolonged anomalous temperatures), so a more persistent if rainy January thaw is coming. Dare we say that we all deserve it after the past few weeks?

Brian Crandall

Brian Crandall reports on housing and development for the Ithaca Voice. He can be reached at bcrandall@ithacavoice.com.