Heat crests Thursday, then storms offer cooling

GRAND JUNCTION, Colo. (KKCO) - The heat has been building this week, and we’ll reach the summit of that heat on Thursday afternoon with temperatures as high as 100 degrees for parts of the Grand Valley.

Our Next 24 Hours

This evening is warm. Showers and storms are scant, but the few that we have will mainly stay over the higher terrain. We will slowly cool from mid-90s around 6 PM to upper 80s by 9 PM. It will probably be midnight before we cool below 80 degrees. We’ll be partly cloudy to mostly clear overnight. Low temperatures by morning will be near 69 degrees around Grand Junction and 63 degrees around Montrose. Be ready for hot Thursday. The day will be mostly sunny. The rare showers and storms that form will mainly stay over the mountains. High temperatures will be near 98 degrees around Grand Junction and 92 degrees around Montrose. Some of us may touch 100 degrees on some of our back yard thermometers in the Grand Valley.

Setting Up For Rain

The most intense part of this August broil will be short-lived and nowhere nearly as hot as the triple-digit spike we experienced a couple of weeks ago. The atmosphere will humidify Thursday night and Friday. A streak of wind passing just north of us will draw a strengthening wind flow about 35,000 feet over the Western Slope. We won’t notice the wind down here on the ground, but that acceleration of the wind overhead will turn the atmosphere into a giant straw. It will lower the pressure and pull the humid air up from near the ground to generate clouds. It will also lead to the formation of some showers and thunderstorms. This upper level wind pattern will most strongly favor increasing showers and storms on Friday and Saturday afternoons and evenings.

Rain May Favor Evenings In The Valleys

Then there’s the humidity... while the humidity is noticeably higher than normal during the afternoons, it’s still quite low. It’s low enough, in fact, that rain will fall from the clouds and evaporate. Many of the afternoon showers and storms will consist of virga and gusty winds, most of the rain won’t reach us on the ground in the afternoons and early evenings. Humidity will increase with the cooling during the evenings, so the evenings may offer a bigger chance for rain as compared to many of the afternoons. That’s not to say there can’t be rain in the afternoons. It’s just going to be more difficult, and it’s going to require the air undergoes some humidifying before the rain can start reaching the ground. The atmosphere has to work toward its goals, too.

Looking Ahead

Showers and storms will begin to subside on Sunday and even more on Monday. A gradual drying trend early next week will come with some warming.

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