Tuesday, June 16, 2009

Missouri Soaker

What an appropriate day to wrap up our Missouri climate chat -- when much of the state is sitting under a flash flood warning.

A complex of storms that developed over eastern Colorado and Kansas on Monday moved in overnight and is slowly pushing across the state as we speak.

A large swath of 2 to 4 inch rainfall amounts has been measured across the region with many reports of flooding from south of Kansas City to St. Louis and across the Ozarks.

Over 5 inches of rain fell in a few isolated locations.

Numerous roads are closed in spots, including state routes E, U, FF, HH, WW, Z, P, W, H, 18 and 123.

Near Marshfield, a spotter reported 1.60 inches of rainfall in just 30 minutes along with 55-60 mph wind gusts.

Annual precipitation follows a similar gradient to the temperatures, with lower values in the northwest and increasing as you move southeast.

Northwest Missouri averages about 34 inches of precipitation each year with southeast counties closer to 50 inches.

Northwest Missouri has a large influence from continental climate influences and sees a pronounced wet and dry trend in their annual precipitation. June is 5 times wetter than January.

But as you move into the southeast counties, where the climate is influenced more by sub-tropical air masses off the Gulf of Mexico, we don't see near the variation during the year as they do up north.

Winters are dry in the northern counties and fairly wet across the south, ranging from an average of 0.8 inches during January across the northwest to about 3.60 inches in the southeast.

However, when we look at the warmer months, July in particular, the wet bullseye moves from the south to the northeast, where the average precipitation is 4.40 inches compared to 3.20 inches in the southwest.

This pattern during July is mainly due to the convection patterns that set up from the thunderstorm cycle over the high plains of the central US. Storm complexes form across eastern Colorado and Wyoming and move east, often staying together overnight and traveling all the way to Iowa and Missouri.

Rain isn't the only form of precipitation that falls over Missouri, snow can be seen as early as October and as late as May in the Show Me state.

However, most snow falls during the climatological winter, which covers the months of December, January and February.

Northern Missouri sees the most snow annually, with 18-24 inches common north of the Missouri River.

The southern counties see 6 to 12 inches of snow each year on average.

It is unusual for snow to remain on the ground more than a week or two in Missouri.

Freezing rain or drizzle can also fall -- but not usually more than 5 times a year on average according to the Missouri Climate Center.

Most of Missouri's precipitation comes from thunderstorms. While storms have been documented each month of the year, the most common months to see storms are April through July.

Hail can also fall any time of the year, although much less common during the winter months.

May is the month with the most hail on average across Missouri.

If you live in Missouri, you can expect precipitation about 100 days out of the year.

Anywhere in Missouri is subject to high-intensity precipitation events.

The town of Holt, on the northeast fringes of Kansas City, holds the title for highest precipitation intensity in the world, having received 12 inches of rain in just 42 minutes on June 22, 1947.

On average, southwest Missouri is prone to the highest frequency of high-precipitation rain events.

Residents in that area can expect to receive a 4.5 inch rain event in a 24 hour period once every 2 years.

Along with all the thunderstorms you can expect to see about 30 tornadoes each year in Missouri.

Of those, up to 8 can be considered violent, rated EF2 or higher.

About 80% of Missouri tornadoes happen between noon and midnight, with the greatest activity between 4 and 6 pm.

Missouri tornadoes are usually short-lived, staying on the ground an average of about 10 miles.

Here is a great link to find additional weather information about Missouri.

Much of the research I did came from the Missouri Climate Center. Click here to visit their web site.


  1. Off topic - did others get this email?

    CoCoRaHS observers-

    You have been identified as a reliable source of data for our office. In the near future, we will be incorporating your daily precipitation observations into our HYD text product (found at http://www.crh.noaa.gov/product.php?site=MKX&product=HYD&issuedby=MKX).

  2. Grinder, yep. I wonder how many other states are doing this?

    I replied telling them that my CoCoRaHS ID obs are the same obs as my NWS COOP ID. I wonder if they'll list my observation twice?

    We'll soon see.