Weather Blog: Too Much and Not Enough Rain

Posted at 9:22 AM, May 15, 2021
and last updated 2021-05-15 11:24:23-04

Good Saturday bloggers,

We are tracking several chances of rain & thunderstorms this weekend. The 1st round occurred this morning on a line from Atchison to Sedalia south. Rain chances are low this afternoon & evening before increasing after midnight.


Periods of rain & thunderstorms are likely all day Sunday. Some locations could see very heavy totals that could lead to some flash flooding. There will be other locations that receive under .50" of rain. The severe threat for all is, fortunately, very low.

Let's go through this.

There is a higher severe threat, level 2 of 5, for much of the western Plains from Colorado to Mexico. Thunderstorms that form out there this afternoon and evening will ride east and northeast and arrive here after midnight. They may be heavy, but most likely not severe.


Also, a warm front will be setting up across the southern Plains. This front will separate highs in the 60s and 70s from highs in the 80s and 90s. Thunderstorms will form on this front this evening to our south. They will head north ahead of the activity coming in from the western Plains. These thunderstorm areas will combine to bring very heavy rain to some locations.


The thunderstorms along the warm front will head north to around I-70 by midnight. So, this is good news for afternoon and evening outdoor activities of which there are many graduations. Highs today will be 65-70. If we see more sun, highs will reach 70-75.


There will be several periods of rain and thunderstorms as a series of disturbances precede a main system that tracks across the region Sunday night. These systems will track northeast towards I-70 before turning mostly east. There will be some dry hours as well, but timing the rain on Sunday is difficult more than a few hours in advance as the computer data we go off of does not handle these disturbances very well. We have to see how it sets up. It does look like there will be much less dry hours Sunday than today.

These areas of rain and thunderstorms will contain very heavy rain leading to some flash flooding issues and perhaps some wind gusts of 30-50 mph. The severe threat is low as the flow aloft is too weak for much severe weather. Now, it's May with thunderstorms, so we always have to watch it.


This is where it gets interesting. First, 7 AM Friday to 7 AM Saturday saw most of the rain in Kansas.

Here are radar estimated rainfall amounts. There was a thin band from Wichita to Great Bend, KS that received 2" to 6" of rain. Our area was on the eastern edge with amounts trace to .10". Emporia to Pleasanton, KS saw .25" to .90".


Here is the rainfall forecast for today through Monday. Check out the range of amounts. .35" at Maryville, MO to 8.7" of rain at Clinton, MO. The Kansas City area is in the 1" to 4" category, heaviest south of I-70. Now, this does not mean Clinton, MO will see 8.7" of rain, but it means some locations south of I-70 will see excessive rainfall.

This band of excessive rain could still shift south or north by 50-100 miles. Or...could it?


Here is the percent average rainfall during the last 30 days. It looks very similar to the rainfall forecast above.


The rainfall disparity between north and south can be shown further as the map above is just the last 30 days.

Here are rainfall totals from 3 locations south to north since January 1st.

Pleasant Hill, MO: 15.56"
Kansas City, MO (KCI): 13.08"
St. Joseph, MO: 8.65"

There is a 7" disparity from south to north in just these 3 locations. So, until proven otherwise, the rainfall forecast above seems correct.

Have a great weekend and stay healthy.