Wednesday, December 20, 2017 –
Good Evening. We certainly have see our share of clouds and rain today. You can see the cloud cover on this satellite imagery from College of DuPage.
Low pressure is moving across the Tennessee Valley this evening. Look at this satellite imagery from NOAA and you can see the spin across west and middle Tennessee.
We will keep the clouds and fog in the forecast through the night with rain early.
8 PM Tonight – Clouds and rain continue with areas of fog.
7 AM Thursday – Clouds and fog will prevail across the region with a slight chance of a shower.
Noon Thursday – Variable cloudy skies are forecast for the area with temperatures in the middle and upper 40’s.
5 PM Thursday – We keep the clouds in the place with afternoon high temperatures in the lower 50’s.
If you like the mild weather, you will enjoy the temperatures through Saturday. Colder air moves into the area Sunday.
We stay mild Friday and Saturday, but rain chances will increase again.
I do want to point out that we could see some locally heavy rainfall across the region on Saturday. Here is a look at the rainfall potential late Friday through early Sunday.
Low pressure will move across Tennessee late Friday and Saturday which will bring the heavy rain threat to the area.
8 PM Thursday – we will have clouds and cool air across the region with areas of patchy fog.
Noon Friday – Our next Weather Maker will increase the clouds across the area through the morning. Rain will be possible through the afternoon.
10 PM Friday – Clouds and rain are in the forecast Friday night.
7 AM Saturday – Look for cloudy skies and rain Saturday morning.
Noon Saturday – Locally heavy rainfall will be possible with mild temperatures.
7 PM Saturday – we keep the rain in the forecast through the night. Some areas could see well over an inch of rain.
Take a look at this upper air map for today. This is a 500 MB chart -18,000 feet. You can see all the black solid lines which are called contours – they connect equal lines of height. What this map is showing us today is that we are seeing what we call a “zonal” flow. This means that all weather is moving from the west tot he east with no real cold air intrusion. The “X” marks an area of vorticity or spin on this map which can generate moisture.
Now look at the upper air pattern for early next week. This is the map at 500 MB or 18,000 feet on Monday, Christmas Day. Cold air will push south across the Ohio Valley and the Great Lakes into the northeast. The coldest air stays north of our area. High pressure keeps mild air across the deep south in Florida.
We will see colder temperatures Christmas Day, but it appears that the chance of accumulating snow will be slim. The higher elevations may see a dusting to an inch late Sunday into Monday with flurries possible Christmas morning across the Tri-Cities. This forecast for Monday could change, but that is what it looks like right now.
Have a great night!
News Channel 11