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Weather Blog - Changes & Clouds

Upper Level Flow Today
Posted at 7:43 AM, Oct 20, 2021
and last updated 2021-10-20 09:50:05-04

Good morning bloggers,

There is a rather difficult forecast ahead of us for the weekend. A storm system will be developing over the plains by Sunday and it may impact our area with a chance of rain and thunderstorms. There may even be a risk of severe thunderstorms. There are big events going on at the Kansas Speedway this weekend, and we will go in-depth on our weather broadcasts today and tonight.

Between now and then, we have a weaker cold front moving through today. Here is a look at the surface forecast valid at 4 PM today:

Surface Forecast This Afternoon

That green and red box was left on there when I saved this picture for the blog. It is a box that pops up when I am drawing in fronts, changing the size of text, and plotting the lows and highs. I just forgot to save it without the box on there. The main storm system is way up over Minnesota and the Dakotas today. This will place us in a dry northwest wind this afternoon and we should still get up close to 71 degrees.

Upper Level Flow Today:

Upper Level Flow Today

The new LRC is developing right before our eyes. Did you know that you, the bloggers, named my theory the LRC for Lezak's Recurring Cycle? In 2002 when we were starting this blog, I discussed my hypothesis with you and we were beginning to make incredibly accurate weather forecasts using this breakthrough technology. In these past 20 years or so, we have learned a lot more, and in the past decade the weather forecasts for winter storms, severe weather outbreaks, tropical storms, flooding events, droughts, heat waves, Arctic blasts, and other significant events have become incredibly accurate. The LRC allowed us to accurately predict seven of the eight USA landfalling tropical systems this year, including a 7-month prediction of the worst weather disaster of 2021, Hurricane Ida.

The new LRC is evolving now, and soon we will be making these predictions for 2022. Right now, a fascinating and unique pattern is setting up above us. On this map above, you can see some blocking over Greenland, and today's storm system, the low just north of us. The blocking over Greenland is shown with that H plotted up there. This is what we call an upper level high, and it is at high latitudes. When these systems develop, it forces the just stream to strengthen farther south, and it often blocks up the flow.

Arctic Oscillation (AO)
North Atlantic Oscillation

The Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) have started this LRC season with a quite fascinating development. The NAO has dipped negative and has stayed below zero. The AO has been higher. I haven't seen this combination in a very long time, so it has my attention. When these indexes dip deeper negative, cold air is almost certain to follow.

Cumulonimbus Clouds:

A cumulonimbus cloud is the largest cloud type. Cumulus means piled up, or a building cloud. Nimbus means rain. So, this type of cloud begins as a cumulus cloud and then grows into these huge clouds that can have bases as low as 500 fee to 1000 feet above the ground to tops as as high as 70,000 feet. These clouds pack a lot of energy and are created when the atmosphere is very unstable.

On Tuesday, there was a thin band of clouds that moved across the Kansas/Missouri state line. These were high based cumulonimbus clouds, or what I call "Alto-Cumulonimbus". Altocumulus and Altostratus clouds form with bases closer to 10,000 feet up or a bit higher. The bases of Tuesday's clouds were at that level, and there was just enough moisture available for these to form rain that reached the ground. It rained for around 5 minutes in a few spots.

Here is a picture I took just after noon yesterday:

Altocumulonimbus Clouds

They zipped east in a changing weather pattern.

Today, even though we are being affected by a storm system to our north, you will barely notice it, as it is a gorgeous day. There will be a breeze shifting to the northwest. Temperatures will warm into the upper 60s to lower 70s. Cooler air will move in Thursday, and then we will look ahead to the weekend changes which include the chance of thunderstorms and rain later this weekend.

Thank you for spending a few minutes of your day reading the weather blog. Have a great day.

Gary