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Weather Blog: Heat dome, Hurricane Hilary

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Posted at 1:45 PM, Aug 16, 2023

Good Wednesday bloggers,

The weather pattern is evolving in to one where our rain chances are dropping and our temperatures will be rising.

So far this August we are running 1° degree below average. This is not as low as you might think as we are 3° below average on highs and actually 1° above average on lows. This is due to the high humidity we experienced this month, keeping lows up. The humidity was turned into a lot of rain in most locations.

Average rainfall for the entire month is around 4.25". There are many locations that are way above average through the first half of August. There are some locations wondering how they missed all the rain. See Lee's Summit, Olathe and south Overland Park.

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We are tracking two main weather features the next seven-10 days. One will have direct impact on Kansas City. One will likely have a direct impact on southern California.

The first weather feature is an upper level high also known as a "heat wave creating machine" and is more often called a "Heat Dome". This feature is basically a big warm area around 18,000 feet. Warm air expands, so it creates a dome like feature when looking at the atmosphere in 3D. This feature creates sinking air, which suppresses cloud and rain development. Sinking air also heats up the air at the surface. During the summer, these features can create heat waves.

Sunday and Monday this feature will become quite large and center itself over our area. This will push the fronts and thunderstorm producing systems way to the north. This means we are likely in for the longest and hottest stretch of weather this summer. The good news is that it will likely breakdown at the end of next week.

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The second feature is a tropical storm, about to become a hurricane, possibly Major Hurricane Hilary. Hilary is forming off the south coast of Mexico. Hilary will not impact our area, but could bring an unusually high amount of rain to southern California this weekend.

You can see in the upper level flow above, the hurricane is getting pulled north into southern California around the western edge of our heat dome. A tropical storm or hurricane has never hit San Diego or Los Angeles as the water is too cool offshore. The systems weaken rapidly as water temperatures are in the 60s, way too cool to support a tropical system. This system will weaken as well and may be remnants as it moves north into California. But, the moisture will combine with the summer monsoon and create very heavy rain in some typically very dry areas.

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Here is the rainfall forecast for the next seven-10 days. The heat dome is well represented with our area in a circle of no rain as thunderstorms track around the periphery of the dome.

You can see the heavy rain signature into southern California into Nevada. Amounts could be in the 2"-6" range! It will be interesting to see how much rain San Diego and Los Angeles receive.

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Back to our area. How hot will it get?

THURSDAY:
The heat gets delayed another two days as a dry cold front sneaks in Thursday. This will keep our highs in the 80s.

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FRIDAY:
The Thursday cold front becomes a warm front and heads our way. We will still be on the cooler side of the front Friday, so we get another day where highs are in the 80s.

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SATURDAY-SUNDAY:
Now, our luck has run out. Highs both days will be near 100° with lows 75°-80°. The humidity will be moderate and also there will be a south to southwest breeze at 10-20 mph. But, hot is hot. Keep this in mind if you are out and about. Drink plenty of water and where light colored, light weight clothing.

We have two big daytime outdoor events this weekend. The KC Air Show in Gardner, KS and the Missouri State Fair.

The Billy Joel, Stevie Nicks concert is at night. Temperatures will drop from the 90s to 80s and with no sun beating down, it will be somewhat tolerable.

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Have a great rest of your week
Stay healthy.