Meteorologist Mark’s Wx Blog for Sun., Jan 17

Headlines 

More snow flurries tonight

Chilly days ahead

Rain showers arrive Wednesday night

Meteorologist Mark’s Wx Vlog 

48-Hour WX

Seven-Day Forecast

Daily Forecast Summary

Today: Mostly cloudy. Snow flurries develop overnight w/ up to a dusting of accumulation.

Monday – Tuesday: Partly to mostly cloudy.

Wednesday: Increasing clouds. Rain develops overnight.

Thursday – Friday: Showers likely.

Saturday: Partly cloudy.

Meteorologist Mark’s Wx Concerns

The best chance for a dusting of snow will be north of the interstate. The closer to Kentucky you are the better your chances.

Meteorologist Mark’s Wx Discussion

At one point this morning, I reduced my confidence to “low” for tonight’s dusting of snow. I then went back and looked at a bit more data and moved my confidence back to “medium”. It’s been a dramatic morning, as you can tell (ha). Areas north of the interstate certainly have the best chance for snow flurries or a snow shower and those chances increase the closer to the Kentucky border you are.

Another rain system moves in by Wednesday night, but models sure have backed off on precip. If this trend continues, rain chances will drop from 50% to 30% even for Thursday. I’ll keep an eye on that.

There are no clear signs of any wintry weather in any of the data from yesterday, last night, or this morning. There had been hints at wintry precip for Friday, but that’s all but completely gone now. Such is the way with extended model data. Trends could still flip back, so I’ll watch it closely.

On This Day in Wx History

1999- About 350 homes and 25 businesses receive damage from straight-line winds in Columbia, Tennessee. At the Shady Brook Mall, huge panes of glass at the entrance are shattered. Forty mature trees are uprooted at the Graymere Country Club. There is $400,000 in damage to the Pepsi Cola plant alone. Overall, $4 million in damages are reported in the city. Elsewhere, softball-sized hail is reported at Pulaski, damaging numerous vehicles. This is the largest known hail ever to fall in Tennessee’s history.

Almanac

Yesterday’s National Temperature Extremes

High: 93° at Camarillo, California 

Low: -4° at Terreton, Colorado

Today’s National Wx Hazards

Snow flakes are flying across the Midwest and Northeast today, as well as across the northern plains.

Tomorrow’s National Wx Hazards

Snowflakes fly across the Midwest again, as well as along the Front Range of the Rockies and the northern plains.

 Sunday Story

Predicting the weather would be challenging enough if there were only one layer of the atmosphere to be concerned with. The fact is that the atmosphere is made up of multiple layers that each behave like a fluid. 

In other words, the atmosphere is like a river, with different layers moving at different speeds, with different temperatures, all changing by the minute. 

When a forecast is made, all layers must be considered. Unfortunately, data from the highest levels of the atmosphere is rather scarce. We rely on weather balloon launches to give us some of that data, while satellite observations provide a bit more. Overall, both offer very limited amounts of data. 

Here at the surface we have an abundance of observations due to an abundance of weather stations here on the ground. 

One example of how important it is to understand all the layers is when we have snow in the forecast. While cold surface temperatures are needed for snow, cold air is drier air. As a snowflake falls into that drier air, it can evaporate. So, while the layer the snow begins in is moist, the air it may fall into could be too dry for snow. 

Sometimes it takes so long for the falling snow to moisten up the surface air mass that all the snow evaporates before ever reaching the ground.  

During severe weather, each layer must be analyzed for wind speed and direction, as well as moisture content. Calculating the tornado risk is dependent upon properly understanding each layer’s behavior. 

An analysis of each layer is necessary to get a forecast right. Just one piece of missing or misunderstood data can completely bust a forecast. 

Considering there’s about 60,000 thousand feet of atmosphere to analyze, it’s a wonder we ever get a forecast right! 

Data from a weather balloon launch. Meteorologists, such as myself, analyzing the data from the surface up, analyzing moisture, wind speed, and temperature as they change with height.

You all have a great day!

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