Update: Tri-Cities to See 4 to 7 Inches by Midnight

UPDATE: 3:31 p.m. Tuesday, Feb. 26, 2013

The National Weather Service has extended its winter weather advisory until midnight Tuesday, although snowfall is expected to diminish in the early evening.

Snwfall will continue to be heavy at times through the early evening, affecting commuters. Accumulations may measure 4 to 7 inches.

UPDATE: 12:51 p.m. Tuesday, Feb. 26, 2013:

The National Weather Service on Monday evening has changed it winter storm watch to a winter weather advisory that begins Tuesday afternoon and extends to 9 p.m. The storm could bring with it 3 to 6 inches of snow by late this evening.

The weather system, which hit states from Kansas to Oklahoma to Missouri on Monday, is expected to hit the Tri-Cities area this afternoon, the National Weather Service said. Precipitation may begin as rain, a rain-snow mix or rain-snow-sleet mix, may be heavy at times, and continue into mid- to later afternoon, when it diminishes in intensity, although it will continue to accumulate into the evening.

Snowfall is expected to total from 3 to 6 inches by late evening, although the weather service maintains this storm presents a higher than normal uncertainty about how much snow to expect.

The snow will be heavy and accompanied by strong winds, gusting to as high as 35 to 40 mph, the weather service said.

Heavy winds will pose the greatest impact, whipping up wet snow and possibly causing very low visibility and difficult travel, the weather service said. Even though the intensity of the snow is expected to diminish during the commute, it is still expected to slow travel significantly.

UPDATE: 10:30 p.m. Monday, Feb. 25, 2013:

The National Weather Service on Monday evening updated its winter storm watch, which begins Tuesday afternoon and extends into the evening. The storm could bring with it more than 6 inches of snow.

The storm, which hit states from Kansas to Oklahoma to Missouri on Monday, is expected to hit the Tri-Cities area Tuesday afternoon or evening, the National Weather Service said. Precipitation may begin as rain, a rain-snow mix or rain-snow-sleet mix, may be heavy at times, and continue into the evening.

The snow will be heavy and accompanied by strong winds, gusting to 40 mph, the weather service said, particularly near the Lake Michigan shore. Conditions will mean reduced visibility and travel could be hazardous.

According to the weather service, there is a greater than usual amount of uncertainty about how much snow to expect. “It appears as though several inches of accumulation are probable … with at least some limited threat for localized accumulations of 6 or more inches,” the advisory update states.

Heavy winds gusting to 40 mph will pose the greatest impact, whipping up wet snow and possibly causing very low visibility and difficult travel, the weather service said.

Heavy snow could complicate late-afternoon commuters, and the weather service said travelers should plan ahead for travel times that could be increased greatly.

Also, if heavy snow does materialize, the weather service said snowfall rates of 1 to 2 inches per hour are possible. Expect heavy, wet snow to increase difficulty shoveling as well.

UPDATE: 2:28 p.m.

If the winter storm watch the National Weather Service issued for Tuesday has you’re thinking, “Been there, done that,” don’t get cocky.

It is, after all, winter in the Midwest, which means conditions can change. Besides, a winter storm watch is a stronger caution than an advisory, like the one issued last week, and the National Weather Service has issued this one with good reason: It says this watch comes in advance of a major winter storm developing over the central part of the nation.

But the National Weather Service admits, in an advisory update issued early Monday afternoon, that there a higher than usual amount of uncertainty about how much snow to expect. “It appears as though several inches of accumulation are probable … with at least some limited threat for localized accumulations of 6 or more inches,” the advisory update states.

Regardless, the National Weather Service is calling for potentially heavy snow and strong winds in northern Illinois.

The winter storm watch is in effect from Tuesday morning through Tuesday evening.

Precipitation may begin as rain, a rain-snow or rain-snow-sleet mix on Tuesday morning, may be heavy at times, and continue through Tuesday afternoon. Snow is expected to taper off into the evening.

The snow will be heavy and accompanied by strong winds, gusting to 40 mph, the Weather Service said, particularly near the Lake Michigan shore. Conditions will mean reduced visibility and travel could be hazardous.

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