Weather Blog - Thunderstorms are in the holiday weekend forecast

Stalling Front
Posted at 7:19 AM, Jun 30, 2022
and last updated 2022-06-30 11:17:19-04

Good morning bloggers,

Thunderstorms are in the forecast for Friday evening through Saturday. Heavy rain is likely in a few spots with up to 5" of rain not out of the question.

Kansas City Forecast Timeline:

  • Today: Nearly 100% sunshine for the third day in a row with no chance of rain. The humidity will be increasing. South winds 5-15 mph with a few gusts to 20 mph. High: 93°
  • Tonight: A few clouds later tonight with a chance of thunderstorms north of KC by morning. Low: 68°
  • Friday: Partly cloudy with morning thunderstorms possible near the Iowa and Nebraska borders way up north. The chance of rain in KC is 10% or less through 3 p.m. The chance of rain will increase to 80% by evening with a very low severe weather risk. The wind will be shifting to a northeast direction by evening north of KC and it will be out of the south farther south. A front will be nearby. High: 90°
  • Friday Night In The Big Town: Mostly cloudy with a 90% chance of thunderstorms. Heavy rain & lightning are likely. There is a low severe weather risk. Low: 65°
  • Saturday: A 90% chance of morning thunderstorms. The rain may taper off by mid-afternoon. The chance of rain is down to 30% Saturday evening. High: 82°

The Setup:

This first map shows the surface setup valid at 1 p.m. Friday:

Friday's Set-Up

The solid black lines are called isobars. Isobars are lines of equal pressure, so the pressure is the same along each line. When they kink up, or bend around, the isobars will show where the wind shift line is located, where the fronts are located.

I plotted this map, shown below. A stalling front may become stationary Friday evening. This will be the focusing mechanism for thunderstorms to organize:

Stalling Front

The black dashed line shows the thunderstorm developing zone. Kansas City is near the center of this zone.

  • We will be monitoring the location of this front closely
  • If thunderstorms form on or near the front, it may push it a bit farther south
  • Heavy rain and lightning are the main risks for this setup

Take a look at the rainfall forecast from this model ending Saturday night:

Heavy Rain In The Forecast

The rainfall forecast from this GFS (American) model shows widespread 2" to 5" totals. This is centered just northwest of Kansas City.

Notice that there is no rain forecast just south of us. There will likely be a cut-off to where the heavy rain falls, and some spots may end up dry. At this moment, this rain cut-off line looks to be around 75 miles south of KC, but it could be farther north or even farther south, and we will try to identify this zone as we move through the next 24 hours.

Severe Weather Risks:

Severe Risk Today

The front is north of us today, and the risk of severe weather extends from Lake Superior southwest to northern Iowa. The risk then decreases as it trails into Kansas.

By Friday, the risk gets even lower. The SPC even said yesterday that there was almost no risk of severe weather at all. The LRC tells us to still monitor this one closely, as it is related to a storm system that came through in the last cycle producing a lot of severe weather around April 4-5.

The jet stream is now much farther north, and the energy is much less in the upper levels of the atmosphere, which will limit our severe weather risk this time.

Severe Risk Friday

The Storm Prediction Center then takes us out of the risk on Saturday. And yet we likely will have numerous thunderstorms in our area Saturday morning. The main risks will be lightning and heavy rain.

Severe Risk Saturday

What is a severe thunderstorm? A severe thunderstorm is defined by three main criteria:

  1. Winds 50 knots or stronger, which is 58 mph or stronger
  2. Hail one inch in diameter or larger, the size of a quarter or larger
  3. A tornado

If one of these criteria is reached, then it is a severe thunderstorm. It can be windy, with winds up to 57 mph or lower and hail the size of a nickel, and this would not be a severe thunderstorm. It would certainly get our attention, however.

For this setup, most of the thunderstorms will likely stay below severe levels with winds gusting to 30 or 40 mph near some of the stronger thunderstorms, and possibly some small hail. The chance of a tornado in this setup is very low.

The Tropics:

As a few of you may remember, Weather 20/20 issued the hurricane season forecast in March, predicting a quieter hurricane season this year. The season has started out very quiet, but we still expect one potentially major hurricane in late August or early September targeting Florida. For now, it is very quiet.

We may get Tropical Storm Bonnie to form later today. It doesn't look organized at all to me, and it is way south. Here is the track from the NHC:

Potentially Tropical Storm Bonnie?

This system will cross into the Pacific this weekend, and that's when it will likely strengthen.

Get that sunscreen on today! The outlook for the Fourth of July is dry with hot weather. Expect a high of around 92° Monday!

Thank you for spending a few minutes of your day reading the weather blog and sharing in this weather experience.

Have a great Thursday,