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Joe’s Weather Blog: The heat to briefly break (WED-7/12)

Good morning…some showers are ongoing across N MO this morning and there may be more activity up there later today as well. Back home into the KC Metro…no rain (yet) but and it’s still toasty but as I stressed over the weekend this is basically just a typical KC heat wave (if we can even really call it that). The dew points have been the reason why temperatures haven’t popped even higher. The higher the dew point the tougher it can be to heat up the air. Dry air (like the desert) heats up more efficiently that moist air does and with dew points hovering around 75° in many areas…it’s just tougher to realize the max potential of the temperatures. So far KCI has been 92° (MON) 93° (TUE) and we should be around 93-95° today (unless clouds hold things back farther). The heat index though has been around 105° and that is what you’re actually feeling out there. There has been a nice breeze though helping I guess.


Forecast:

Today: Partly cloudy with more sunshine from KC southwards. Highs around 95° with heat index values close to 105° again.

Tonight: Mostly clear with some rain/storms possible in N MO. Muggy again with lows in the 75-80° range

Thursday: Variable clouds with showers/storms possible later in the afternoon especially (earlier in N MO). The amount of clouds will determine the higher. We again could be in the 90-95° range with enough sunshine before the storms try and pop after about 2-4PM or so in the KC area. Those storms could be strong to severe in some cases with wind and hail being the main threats along with locally heavy rain.

Friday: The heat will break with highs closer into the 80s and could be cooler with some additional rain/clouds in the area.


Discussion:

Over the weekend, I indicated that this would really be a mini heat wave. While there really is no definition for what a heat wave is…I’m not sure this actually qualifies except for the fact that the heat index has been rather stout (but again very typical of July in KC). Downtown in KC has hit 95° (MON) and 96° (TUE) which is also not exactly unusual for this time of the year. Remember that the average high is around 88° at KCI and close to about 91° in Downtown KC. So really we’re talking about temperatures that are 5° or so above average.

Things though are going to change as we finish off the week. This past weekend in the blog and on the air I alluded to this potential. The model data was sketchy on this potential (the GFS was as usual horrendous with this potential) but I was thinking a cold front was going to be impacting the area and this appears to be coming to fruition. That’s good news because we should get at least a break from the mid 90s and see at least the chance of rain come into play over the next 2 days. Thursday and Friday will offer up chances at least. Can’t promise widespread coverage yet but the potential for some locally heavy rains are there. These summer time storms typically can be slow movers and there is a lot of water vapor in the air so there could even be some flash flooding if a storm sets up in the right spot. Some hail is not out of the question as well as some wind gusts to near severe levels.

This thunderstorm activity would be connected to a cold front coming in from the north. The front will be drifting towards N MO tonight then gradually sagging southwards Thursday.  This morning the cold front is up in NE and far NW KS.

Ahead of the front the usual warm moist flow continues a the surface. The front will gradually drift south today and should spark storms later today and this evening in the unstable air across N MO. Those storms will help to slowly push the front southwards tonight and tomorrow. One issue about the forecast for Thursday is the amount of debris cloud cover that will be generated by the activity tonight. Enough debris clouds can help keep temperatures a little less hot Thursday. Without those clouds we’re right back into the hot stuff.

Behind the front there should be a decent humidity break for FRI>SAT. It won’t feel nearly as nasty has it has for the last several days so that is a good thing.

By Thursday afternoon the front should be near the KC Metro area…if not in it.

The map above shows the CAPES or the amount of Convective Available Potential Energy that is available…it’s well above 2000-3000…which indicates a likely very unstable air mass on top of the area. With a cold front helping to create a focus point and no real cap in place by then…we should get at least some storms to fire up. Again wind/flooding/hail would be the main threats from the storms.

According to the SPC the risk for severe storms is considered “marginal” at this point. One of the negative factors would be a relatively light wind regime in the atmosphere as you go upwards. Still though…there could be some good storms out there later tomorrow into tomorrow evening I think.

IF we miss out on the rain chance later THU and FRI AM…then I’m not exactly sure when we get additional rains…because there are decent to strong signals that the heat will come right back into the area next week…again odds favor mid 90s BUT as the week goes along we may start to see things drying out a bit more (depends on the rains THU>FRI) and if that is the case it may actually get hotter later next week. So the rains before this weekend will determine the extent of the humidity next week to a certain degree.

With our terrain being so “green” right now, it acts as a counter to extreme heat (but it contributes to the nasty dew points). Here is a 4 part chart that shows this. Notice the “greenness” factor around the region. Also notice the lack thereof across the NW Plains and MT…that’s where the drought is expanding right now.

IF you look closely we’re actually more “green” than average for mid July. Tough to get to 100 with that look. It’s not impossible…just tougher.

For farmers this is an important time (especially for the corn). A well timed rain in the next 1-2 weeks could help the crop tremendously.

Soybean farmers have a bit more wiggle room…

Finally during this time of the year the tornado threat drifts northwards more and more (closer to the jetstream). Yesterday there were some interesting videos coming out of IA as well as ND.

OK that will do it for today. I should get another update out on Thursday. Our feature photo comes from David Lawson of a cloud illuminated by lightning last Friday night (south of Raymore)

Joe

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