Next Arctic Blast - Rain Followed By Snow

Our next cold front likely stronger than the last

We will enjoy just a slight moderation in temperatures this afternoon as highs warm into the lower 40's. Even better, skies will continue sunny to partly cloudy for our Saturday with light winds expected.

Cloud cover and light rain arrive Sunday

Clouds will quickly increase Saturday night and Sunday with light rain expected to hold off until late in the day. Despite the clouds, temperatures will be slightly warmer Sunday afternoon and Sunday night as southerly winds help to push temperatures in to the middle and upper 40's by the afternoon hours. Some good news ... Temperatures will not fall much Sunday night, holding well above freezing with lows in the 40's. Precipitation will continue to fall only as rain, even in the mountains of Tennessee and North Carolina.

Rain eventually changes to snow before ending 

Rain will continue through the day Monday, and possibly heavy at times, with a 1/2" to 3/4" of rainfall expected. Temperatures will hold near 50 degrees through the early afternoon hours, even across the mountains of North Carolina. When will the cold air arrive? We turn sharply colder late Monday afternoon with rain quickly changing to snow late Monday afternoon or Monday evening with the exact timing still uncertain. 

Developing storm moves quickly and leaves only minor accumulations

Nine times out of ten, when a low pressure system emerges out of the Gulf of Mexico, it doesn't strengthen quickly enough to have a meaningful impact on the Tri-Cities. This will once again be the case. Only a dusting to an inch of snow will be possible Monday night in the Tri-Cities with one to three inches possible across the mountains (on average). The storm will rapidly strengthen as it moves past our area leaving several inches of heavy wet snow and dangerous traveling conditions across parts of West Virginia, Pennsylvania and New York.

Arctic Air Mass Not Here Yet Despite Chilly Temps

Cooler Today, Arctic Chill Holds Off Until Tomorrow Afternoon

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A weak cold front made it ways across our region last night, but a much colder air mass is poised to bring an Arctic chill to the area late Thursday. The forecast model below (NAM Model from weather.unisys.com) indicates 850 mb temperatures for this afternoon. The purple and pink colors indicate the location of the Arctic air mass to our north.

Even though this image illustrates the air temperature several thousand feet above the surface of the earth, it is a good forecasting tool for temperatures and weather conditions at the surface.

My friends, for those of you that would like to have a better understanding of weather models and how weather systems behave, this blog post is for you. My goal is to provide you the forecast along as well as a better idea of the science behind forecasting. Parents and teachers ... this is an excellent way to explain the science of weather to your children, especially 8 years old and up. Of course, some of the posts on my blog will be more technical than others.

 (These images can be viewed on weather.unisys.com. Questions and comments are always welcome here on Rob Batot's WeatherWorld)

The Arctic chill begins to arrive Thursday afternoon and by Friday morning we will have to bundle up and prepare for temperatures in the lower to middle 20's. Continuing with the same NAM forecast model, notice the purple colors below that now encompass our region. 

There is also a scale at the bottom of this forecast model. Notice the purple color is indicates temperatures ranging from -10 to -20 degree Celsius. This converts to 14 to -4 degrees Fahrenheit. However, since this represents temperatures for several thousand feet above the surface and since we will not experience the coldest part of this Arctic plunge, our coldest time period will be Saturday morning when lows fall to between 14 and 19 degrees Fahrenheit.

The Arctic air mass will begin to retreat Saturday afternoon as seen in the image below. Notice how the purple colors are once again located to the north of our region by Saturday afternoon. Since cold air is heavy, it will linger in place at the surface of the earth, so our high temperatures will only climb into the 40's Saturday afternoon. When an cold air mass retreats like this, it takes another area of low pressure to develop before the Arctic air is once again pulled back into our area.

I have included two images below (AVN forecast model) that highlight the formation of a low pressure system that will likely bring Arctic air back to the Southeast late Monday into Tuesday. These images are for Monday morning and indicate a Gulf of Mexico, low pressure system beginning to develop. 

The images indicate temperatures and precipitation for Monday morning. The very bottom forecast model indicates precipitation developing across our region. However, with the Arctic air mass remaining to our north, the precipitation will fall as rain, even across the mountains. The temperatures at 850 mb, as seen below, indicate above freezing conditions throughout our area. Lows will likely only fall into the upper 40's Monday morning. 

At this stage in it's development, the low pressure system is simply not strong enough to have pulled the Arctic temperatures back into our region.  Therefore, only rain is expected for Monday morning. Temperatures will not be cold enough to support snowfall. To see if this changes by Monday afternoon, continue reading Rob Batot's WeatherWorld. Don't miss important weather updates, register for Email Updates at the bottom of my blog.