Weather Blog: A Fourth of July Weather Pattern Shift

Posted at 10:40 AM, Jun 28, 2021
and last updated 2021-06-28 18:27:19-04

Good Monday bloggers,

We are in for 4 more cloudy days with periods of rain and some thunderstorms. The pattern has set up in such a way that tropical moisture is tracking north from the Gulf of Mexico and eastern Pacific Ocean. This comes right after a pattern of west-northwest flow last week that brought 2-3 days where large clusters of thunderstorms tracked across the Plains.


Prior to last week, most locations needed rain. Here are the rainfall totals from selected cities through June 20th. Keep in mind May and June, are on average, the wettest months of the year. Olathe was sitting at 0.11" of rain.


What a difference a week makes. Rainfall through June 27th has seen Olathe's rainfall climb from 0.11" to 2.68". Chillicothe, MO still leads the way jumping from 2.75" to 8.74".


This is the radar estimated rainfall from the last 7 days. The rain was needed in many of these locations, but there was too much of a good thing across northern and central Missouri. The rainfall in the Kansas City metro was heavy, but not excessive. If you look closely, there is a small dent in the heaviest rainfall totals around KC. So, the rain was beneficial and brought locations south of I-70 in KC to still 50% of the June average with 3 days to go.


This second wet pattern will hold through Wednesday before breaking down Thursday, just in time for the 4th of July. Locations south of I-70 may finish the month around or just below average for June. The official total for Kansas City, KCI airport, will likely finish the month above average, as by the 27th, the total was 4.48".

This is the rainfall forecast for the next 5 days. You can see the result of the tropical flows as there is a band of heavy rain from Mexico to southeast Canada.


When we zoom in you can see 2"-5" or more of rain is likely along and east of I-35 through Thursday. West of I-35 amounts taper to .10"-1" in the northwest corner of Missouri. The lower rainfall in northwest Missouri, upstream of KC, will help our river and stream flooding. But the 2"-5"+ of rain from I-35 south will be a flood issue from southern Missouri, eventually to the Gulf coast. Especially when you add in the water from last week.


Here is the forecast.

Periods of showers and thunderstorms, very heavy at times. The severe threat is very low to zero. The heaviest and most frequent rain will occur along and east of I-35. Timing the rain is very difficult, but basically each day can have a total of 10-15 non-consecutive dry hours and 10-15 non-consecutive hours where there is rain and thunderstorms. Highs will be around 80 with lows 65-70.

The tropical flows pattern will break down as an upper low forms over the Midwest, east of the Mississippi river. This will turn our flow to the north and with our area west of the system, we should have drier air, drier days. Highs much of the holiday weekend will range from 75-85 with lows 55-65. You can't ask for better temperatures this time of year around here.

There is one potential fly in the ointment as they say. You can see the showers around the upper low from around the Mississippi river eastward. There is a chance the upper low drifts west. If it does, and it shifts west by 100 miles, we could see a few afternoon showers on the 4th. The heavy rain shifts to the southeast USA.


Have a great week and stay healthy.