Monday, December 19, 2016

Pattern Change Could Bring Rain for Christmas - Likely Travel Impacts

Temperatures for the month of December have been well below average, especially within the past couple of weeks.  But that pattern is about to change with milder air arriving at the end of this week, just in time for Christmas.

A big dip in the jet stream will develop out west forcing a ridge in the jet stream over the Great Lakes and East Coast.  With this pattern change, an area of low pressure will develop in the Plains and lift into the Mississippi River Valley by Saturday afternoon.  Weather forecast models are taking that low west and northwest of Northern Illinois Christmas Eve and Christmas Day, placing the Stateline well within the warm sector of the storm.  This means temperatures could warm into the 40's, and even 50's where there is very little snow cover on the ground.  High pressure in the southeast will allow Gulf moisture to be pulled well north into the Great Lakes during this time suggesting a rainy Christmas Day, and possibly even some thunderstorms out west.

Temperatures this week will warm, but won't warm fast enough for us to get rid of all the snow we have on the ground.  So a slight southward shift in the track of the low is possible.  However, I do think there is potential for this next storm system to be warmer because our temperatures leading up to the weekend will be warmer as the overall pattern shifts from the deep freeze to more seasonable.  If we end up seeing mostly rain in and around Christmas Day, this could lead to some flooding concerns with the melting snow and heavy rainfall. 

If you're planning on traveling this weekend, pay attention to the forecast.  While it's unlikely at this point we'll be dealing with a snowy winter storm, rain or even a wintry mix could impact your holiday plans.

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