Monday, January 27, 2014

Winter Storm Warning

By Jay Grymes & Steve Caparotta

A Winter Storm Warning is now in effect for all of the WAFB viewing area from 6 AM Tuesday through 6 AM Wednesday. A Winter Storm Warning is issued when accumulations of ice and/or snow are expected.

The latest in a series of Arctic cold fronts moved through the area on Monday, with the brunt of the cold air lagging just a little bit behind the front. However, temperatures will drop steadily through the night and likely reach freezing a couple of hours before sunrise around metro Baton Rouge (and sooner farther north).

As the cold air spills south, an upper-air disturbance moving in from the west will help to lift moisture up and over the cold air at the surface -- a pattern we refer to as overrunning. This overrunning pattern will lead to widespread precipitation, with the big lingering questions being how much and in what form. Here's our best estimate of what can be expected for different parts of our viewing area as of Monday evening.

Expectations for Tuesday's weather around metro Baton Rouge.

Expectations for Tuesday's weather for areas north of Baton Rouge into SW Mississippi.

Expectations for Tuesday's weather for areas south of Baton Rouge.

There have been a couple of key changes in the model runs on Monday compared to what they were showing on Sunday. First, in general, the models are now forecasting lower amounts of precipitation than they were on Sunday. While that's certainly some good news, we still expect enough ice and snow to cause significant travel disruptions and road closures. Second, the models have been suggesting the precipitation may end a bit sooner than forecast on Sunday. If that occurred, it would mean a reduced window for potential snowfall and a greater chance of seeing most precipitation in the form of freezing rain and sleet. This part of the forecast is especially tricky, but we still think there's a pretty decent chance of some measurable snowfall around metro Baton Rouge and for areas farther north.

The models are in agreement that any precipitation should end late Tuesday night/early Wednesday morning, well before sunrise. The problem then becomes lingering temperatures below freezing that prevent a quick thawing of remaining ice. In fact, we're forecasting Wednesday morning lows near 20°, so we'll be facing the prospect of lingering ice and a hard freeze. What's more, Wednesday afternoon temperatures may only climb above freezing for a few hours, again limiting the potential for significant melting of ice. That could spell another morning of ice on bridges and overpasses as temperatures return to the 20°s on Thursday.

The good news is that a significant warm-up arrives after Thursday morning and any remaining ice would likely melt during the day. And can you believe highs are expected to reach the 70°s by Saturday? We'll be going from a deep freeze to possibly short sleeves by the weekend!

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