Friday’s Ice Situation Still Unclear

Areas in pink could see a glaze to 1/10" of ice accumulation.

Areas in pink could see a glaze to 1/10" of ice accumulation.

The evening model guidance is rolling in, and unfortunately, we are no closer to a definite answer on the threat of wintry precipitation on Friday morning. There are two models that are usually good at catching events like this, and both of them are very consistent with differing opinions.

The RPM model run by WSI is much more aggressive with cold air moving in Thursday and Thursday night, and therefore, it pushes everything south of where the NAM suggests it will be. The area of low pressure developing out in northeast Texas will follow the leading edge of that cold air, so if it is farther south, the whole event will be farther south than most model guidance forecasts right now.

Here’s the RPM forecast for 9 AM Friday:
Screen Shot 2013-01-23 at 9.00.34 PM

The NAM brings the low farther north and shoves the coldest air northeast of the Tennessee Valley; that would leave us with more rain than anything AND a warm-up into the 40s in the afternoon.

Screen Shot 2013-01-23 at 9.00.10 PM

So this presents yet another challenge!

The Bottom Line:

    • Ice is looking like a legitimate problem early Friday morning for some in the Tennessee Valley. The most likely places for slick spots on roads & bridges are in the areas highlighted in pink:

      Areas in pink could see a glaze to 1/10" of ice accumulation.

      Areas in pink could see a glaze to 1/10″ of ice accumulation.

    • Hazardous travel is possible in some of the icy areas; that is particularly the case for Monte Sano, Keel, Green, Brindlee, Sand, Lookout, and Cumberland Mountains in Northeast Alabama as well as the Cumberland Plateau in Middle and East Tennessee. The travel issues will hinge on which model guidance is most accurate.
    • The time frame for this is from about 2 AM to 9 AM in Madison, Morgan, Limestone, Marshall, Giles, Lawrence (TN) and Wayne. It could last longer in those higher elevations above 1200′ from Huntsville east and north.
    • School/business delays? We don’t make those decisions, so I won’t speculate as to how that will work Friday morning.  Some school systems have already notified us of delays – see this list on

Connect with me!
Google+: Jason Simpson
Facebook: Jason Simpson’s Fan Page
Twitter: @simpsonwhnt