A mixed bag of weather

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Main Threats

Thurs night/Fri morning: possible light accumulations of snow and sleet.

Summary

It’s a cold day on the plateau and we have rain moving in. Rain may begin as a snow/sleet/rain mix and it may stay a bit of a mix throughout the day and night. The good news is that temps here at the surface will be just above freezing, preventing any travel issues or any accumulation. Tonight, temps will hover in the mid 30s as warm air tries  to move in. That warm air won’t make much of a punch into our area, but it should be just enough to keep us above freezing.

On Thursday, temps will be dropping as colder air moves back in. This should change any leftover moisture to some snow flakes. We could get a dusting or so, but most of the moisture should be gone by the time the coldest air arrives.

The weekend is looking great! Be sure and plan to get outside if you can! Mornings will be chilly but the afternoons should be quite pleasant.

Discussion

The system bringing us precipitation today is an upper-level low. You’re probably most familiar with surface lows, with their warm fronts and cold fronts. But we also have areas of low pressure that reside in the upper levels of the atmosphere. Remember, the atmosphere is like a layered cake, with layer upon layer extending up from the surface. Great, now I want cake.

Moving on…

This system is in the uppermost layers and is currently spinning over Arkansas. These systems are very cold-cored and can drop a lot of snow on areas that may even be a bit above freezing. These systems make forecasters nervous because data is so limited from up there and we have to do a lot of forecasting using our own skills.

The good news for us (if you don’t want snow) is that we will be on the east side of this system. That means we’re on the warmer side where south winds will be blowing. Since this system is in the upper levels it can’t pull up a lot of warm air but the subtropical jet is so close to us that warm air from it will be drawn in. This will be just enough to keep us safe from accumulating wintry precip. We should still see some fall, but it shouldn’t be able to accumulate.

This is not the case for folks out in West TN and up into Illinois. A major winter storm will develop for some of those areas, with over half a foot of snow possible in isolated locations. Those heftier snowfall totals will be north of West TN but it’s close enough to them to make them a little nervous.

These upper level lows are what often bring snow to the Deep South. I’ve seen these systems drop several inches of snow on Louisiana, Mississippi and Alabama. Sometimes these snows are surprises and that can be a nightmare for southerners. These systems can bring snow because they are up high in the atmosphere and can’t efficiently draw up warm air from the Gulf like a low at the surface can.

Whenever you hear of thundersnow, it’s often the result of an upper-level low. These systems are very dynamic and the temperature drops drastically with height these systems. Temperatures are so cold at the center of these upper-level systems that temps in the lower 30s at the surface seem tropical. That means there’s a lot of “warm” air rising, which leads to convection and possible thundersnow.

Tropics

We still have a system near Puerto Rico but it is looking less organized. It probably won’t become a storm before the environment becomes even more hostile.

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Records

Hardly anyone was cold east of the Rockies on this date in 1989. An unseasonably intense period of warm weather sent highs soaring to 70 degrees as far north as New England! For perspective, they are in the low to mid teens right now (9:00 a.m.). Much of the Southeast had temps in the 80s this day.

During this “heat wave”, Dallas, Texas nearly hit 90 degrees for a high. when they recorded their November record high of 89 degrees…for the second time this month! Waco not only made it to 90 degrees but actually exceeded it by one degree, recorded a high of 91 and establishing a new record high for the month.

Almanac

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News

Continue to keep all those affected by the California wildfires close to your hearts today. I just saw where stocks for PG&E have plunged 14% amid concerns that the utility company may be responsible for the Camp Fire. The power company released a statement saying that there is no way their insurance would cover the damages if the company is found at fault for starting the fire.

At least 42 people have now lost their lives to the fires. At least 7,600 structures have now been destroyed, which is a record for the state.

 

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