ITHACA, N.Y. — It’s been an abnormally warm March, but hopefully you didn’t put away the shovels just yet; a developing storm system will result in a significant late-season snowfall with several inches of heavy, wet snow across Tompkins County by Thursday morning. A Winter Weather Advisory has been issued.

UPDATE: The afternoon model runs have dialed back on the snowfall significantly; as a result, the initially forecasted amounts of up to 12″ shown in the morning runs are now unlikely to materialize in Tompkins County, as the area of most significant snow has shifted eastward towards the Catskills. At this time, Ithaca is now only expected to receive 3-4″ overnight, with 6″ possible in the higher elevations.

As previously forecasted in the Sunday weekly weather, a pronounced frontal trough extends from Canada to the Gulf Coast. An area of low pressure will ride northward along that trough, destabilizing the atmosphere further and ushering in deep Gulf of Mexico moisture. The unstable, moisture-laden air is moving into the area this afternoon.

The latest model guidance has raised the amount of snow expected from about 3-4″ to upwards of six inches of snow, as the track of the low has shifted eastward, allowing for cold air to wrap in more quickly while also tapping into oceanic moisture as it passes over Long Island and Cape Cod.

Tompkins County will remain in the warm sector for the rest of today, so one-quarter to one-half inch of rain is expected through midnight, with heavier bands passing through in the 4-8 PM period. Temperatures will drop steadily from the mid 50s now to mid 40s by sunset, and falling back further into the 30s by midnight. A transition from rain to a heavy, wet snow is expected to occur in the 12-2 AM timeframe. Valley areas can expect upwards of 4″ by morning, while hilltops may see up to 6″, as they will transition over to snow sooner than the warmer valley areas. Areas south and east of Ithaca will in general change over to snow later in the night than Ithaca and towns to the north and west.

Snowfall rates of 1″ per hour are expected overnight, and this will quickly accumulate on roads. Travel may be difficult Thursday morning, especially before sunrise. With temperatures near freezing and ample moisture aloft, the snow will have a high liquid water content – this heavyweight, wet snow will weigh down power lines and tree branches, and may be a challenge to shovel, so pace yourself when clearing off sidewalks and driveways, and if you’re elderly or your health is at-risk, consider asking for assistance.

Another 1-3″ of snow is possible Thursday morning after sunrise as strong northwest winds produce lake-enhanced snow showers across the Finger Lakes. The combination of wind gusts up to 30 MPH and heavyweight snow may result in some localized power outages, and temperatures in the mid 30s will feel like they’re in the lower 20s. Snow showers will slowly taper off overnight Thursday into Friday morning, with lows in the low 20s.

Friday will be cold with highs in the mid 30s and a few lingering snow showers. Temperatures will recover into the 50s for the weekend. The snow should melt fairly quickly with the warmer temperatures and high spring sun angle, and temperatures in the 50s and 60s will make quick work of what remains through the weekend.

Brian Crandall

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