Brett’s Blog (Rainy Stretch Continues)

There’s rain in the forecast for Thursday.  That’ll be the sixth time it’s rained in Kansas City over the last dozen days.  In that time we’ve netted 2.58 inches of rain.  You can thank an active west to east flow aloft for the suddenly wet weather pattern.

As winds aloft are racing over the Rocky mountains, low pressure areas are developing and heading on the Leeward side of the Rocky mountains.  These Lee side lows then race out across the plains.  We see the next storm in it’s infancy on our midday satellite snapshot.

Since the circulation around a low pressure system is counter-clockwise our next storm and recent storms pull moisture northward from the Gulf of Mexico.  In some cases there has been a lot of available moisture.  Since the air tends to rise near areas of low pressure, clouds can grow vertically and eventually into showers or thunderstorms.  In a nutshell that’s what’s happening between now and Thursday afternoon.

 

While the surface winds are from the south tomorrow.  The winds higher up in the thunderstorm may be from a different direction. This is known as wind shear and that change in direction with height can create thunderstorm updrafts. Updrafts can keep water droplets suspended in the clouds creating some severe hail, even in Summer.  Thursday’s thunderstorms will have the potential to create some isolated hail stones larger than quarters and that’s why the Storm Prediction Center has placed KC in a “Marginal Risk” for severe weather.

The better chance for severe weather will closer to the Low pressure area in Nebraska where the temperature profile will be the greatest.  In this region the air aloft could be much colder than the air closer to the ground.  This could create stronger updrafts over Nebraska and South Dakota and will create a small threat for tornadoes in this region.

The tornado threat in Kansas City and surrounding towns is very, very low at this time.  Our biggest threats will be lightning, marginally severe hail and downpours which could lead to some isolated street flooding.  Three out of the four computer models we commonly look at spit out an inch or more of rainfall for this next storm.

Ah, but do you notice the one model generating a lot less rain.  This must be watched because once again thunderstorms on Thursday will be heavy in some places and just brush by other backyards leaving some with lighter amounts of rain.  And while it appears it will rain Thursday it also appears the weather pattern may turn dry as we head into September.