Storm system brings mixed bag of snow and ice Tuesday

Storm Timing

The Finger Lakes will get caught in the crossfire as warm and cold air battle over the region on Tuesday.

Before this system rolls in, a weak disturbance is passing through the Finger Lakes Monday morning with a bit of light snow.

This snow should dissipate during the course of the morning with no more than a coating falling. A little filtered sunshine will be possible this afternoon as thin clouds work in ahead of Tuesday’s system.

Temperatures Monday will top out in the low 30s.

Precipitation will move from southwest to northeast into the Finger Lakes in the hours leading up to dawn on Tuesday. Precipitation will be over the entire region by no later than 8 am.

Cold air will be plentiful early on in this system and precipitation should fall as snow through the morning. The snow will become especially have after 9am with rates of one-inch per hour possible.

Warm air will begin to work in well above the surface, changing the snow to sleet during the late morning and early afternoon. The precipitation intensity should drop during the mid to late afternoon.

As warm air continues to deepen, the sleet will eventually turn over to a period of freezing rain during the evening. The precipitation may become steady again for a while before tapering to freezing drizzle around midnight.

For a refresher, the difference between sleet and freezing rain is as follows. Sleet falls as ice pellets, while freezing rain falls as rain, but then freezes upon contact with the ground.

Precipitation will then wrap around the backside of the low pressure and cold air will return, changing everything back over to snow before dawn Wednesday.

Periods of snow will continue through Wednesday.

Blustery winds will be possible Tuesday and Tuesday night, mostly over higher elevations where gusts of 40 mph will be possible.

Stronger winds will be more widespread on Wednesday with 40-50 mph gusts to the west and 35-45 mph gusts further east.

Storm Impacts

Any time there is a multi-phased mixed precipitation event, the uncertainty is high. Timing the change over from one precipitation type to the next is one of the hardest forecasts to make in meteorology and these events are often full of surprises and hyper local variations.

Counties served by the National Weather Service in Buffalo have Winter Weather Advisories in place for moderate snow and ice accumulations. Onondaga county has a Winter Storm Warning with the National Weather Service expecting more snow (though I do not necessarily agree with that). The remainder of the area is under a Winter Storm Watch. Watches are a precursor to either advisories or warnings and are issued when there is still uncertainty in the storm impacts. Expect these watches to be changed to advisories (most likely) or warnings (less likely) later today. As a reminder, these alerts are issued by the National Weather Service and do not always match up with my forecasts.

Generally speaking, I expect 2-5 inches of snow to fall Tuesday morning. This snow will be wet and heavy. Sleet accumulates slowly, so only expect an inch or less of sleet. A coating to perhaps a tenth of an inch of freezing rain will fall. The highest freezing rain amounts will be over higher elevations.

Travel conditions will deteriorate quickly Tuesday morning as the snow increases in intensity. Sleet and especially freezing rain will continue to keep roads slick and hazardous through the evening commute and into the overnight.

Wednesday will likely have some improvement on major roads, but many secondary and rural roads will probably remain messy.

Should more freezing rain fall than expected, power outages would be possible due to the strong winds. Even without much freezing rain, some sporadic outages will be possible.

Temperatures at the surface are unlikely to ever get above freezing during the duration of this event. The lack of a thaw and the long duration make this an impactful event.

Given the nature of this storm with its multiple hazards and high uncertainty, I will not have a snow map or ice map. Remember, we are generally expecting 2-5 inches of snow, an inch of sleet, and up to a tent of an inch of ice, but there will be variations in this, sometimes over small distances.

The bottom line is that, no matter how the snow-sleet-ice amounts end up, travel will be hazardous, so please use appropriate and due caution.