Joe’s Weather Blog: Watching storm potential for Wednesday (TUE-3/29)

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Good morning…pretty sunrise out there to start the day after a fantastic Monday in the area with highs yesterday in the middle 60s. Today should be about 5° warmer with more clouds and more of a wind kicking into the area. Storm chances and the severe weather risk will be the subject of the blog today.

Forecast:

Today: Partly sunny and pleasant with highs around 70° and SE winds of 15-30 MPH

Tonight: Partly cloudy and mild with lows in the 50s

Wednesday: Cloudy skies with scattered pockets of drizzle possible during the day, then storms possible later in the afternoon or evening. This would be the storm potential to be alert for in terms of bigger storms. Highs close to 70°. Gusty winds of 25-40 MPH possible.

Discussion:

Late last week we had a handful of severe storms move through the region. Some hail (mostly under 1″) and gusty winds (50-60 MPH) were reported from the storms if you remember. There was also locally heavy rain.

We may be setting up for much the same thing later Wednesday into Wednesday evening. While certain parameters are favorable for severe storms Wednesday there are still some concerns about just how unstable we’ll be locally with plenty of low gray clouds expected to cut down on the heating and also then cut down on the local instability. Should we have more sunshine and warmer temperatures then we could see more action in terms of stronger storms (gustier winds and larger hail in some areas). Also there is a question about where the storms actually form. IF farther to the west and NW of KC..then the storms would strengthen then weaken as they come into the state line area where the instability will be less. IF the sun though is out more than I think…then those storms will maintain themselves better. Another issue is what happens during the day (later morning and early afternoon in SW MO. IF there are a lot of storms down there, we’d then be bringing that more stable air northwards because of south winds…it was something that happened several times last year when we had these types of risks. So again not a slam dunk.

Basically in my opinion it’s NOT a slam dunk that we’ll have a lot of severe weather in KC Wednesday. Certainly something to watch though…

The 7AM surface map shows the main concern moving into TX this morning…moisture.

Notice the dew points in green in the map above…dew points in central and southern TX are now into the 60s and there are near 70° dew points in the western gulf of Mexico…notice as well the wind flow coming straight off the Gulf and then the air is coming into central TX. Here is another way of looking at it via windyty.com

As the sun gets higher in the sky today…the visible satellite pictures will show the moisture in the form of clouds across that area…

That moisture will surge into the region later tonight into early Wednesday so that when you wake up we should have pretty gray conditions and a decent wind blowing. In these scenarios, some drizzle or even a few showers are possible as the moisture thickens.

This moisture will be about 5-6000′ thick, Above that there should be a layer of warmer air…this is what we call the cap. This will prevent much vertical development of that moisture keeping it trapped below 6000′ or so. It’s not an overly strong cap though…but it should be strong enough to hold most convection at bay through the afternoon.

Tomorrow evening the temperatures in the mid levels of the atmosphere will be cooling off. At around 10,000′ the temperature will be dropping about 10° from 5PM-10PM or so…that will be enough to remove any capping present and allow any convection to grow especially farther westwards.

Right now the best thoughts are that storms should fire off towards the west of KC…from near Falls City, NE southwestwards towards Topeka and Emporia. Those storms would then move NE and ENEwards at 45-55 MPH! When you get those fast storm motions it’s a signal that the winds pushing the storms above us are pretty fast. It wouldn’t take much for any storm to take those stronger winds above and bring them down closer to the ground…that’s why some near severe level winds are very possible with the storm. Hail is somewhat of a concern but nothing out of the ordinary for KC (typically 1″ or less).

I still think the tornadic threat is pretty low for the KC area. One area that we’ll be watching (again with instability questions) is NW MO and north central MO which may be closer to a surface low in SE NE. Sometimes given favorable parameters…there may be a tendency for stronger storms up north towards the IA state line area…somewhat like last week if you remember.

nam_cape_mslp_mc_15

This map shows the CAPE values (a way to measure instability) and also the position of the surface low (black lines are isobars [lines of equal pressure]). Notice the increased CAPE values west of KC at 7PM…more instability out there.

Now let’s move 3 hours later…and this makes me wonder…notice the best instability is farther west still…BUT whatever storms form out there earlier are moving through our area, when the instability isn’t as strong. I think the model is reflecting the lower instabilities towards the state line area because of a lack of heating and low clouds present for much of the day.

nam_cape_mslp_mc_16

10PM CAPE values and surface map…again better instability is farther west…let’s see OF that moves closer to the state line so that when the storms form out west they can tap more unstable air closer to KC. That may not happen though.

The SPC has us in a “slight” risk of severe storms.

That certainly is a prudent forecast…BUT as I’ve said a few times…NOT a slam dunk situation. It’s one which we’ll just have to see how long the low clouds linger…are there substantive breaks in the clouds to pop the temperatures later in the afternoon in KC? Again things that will be nowcasted for tomorrow afternoon.

Have a great Tuesday and enjoy the mild weather…one last nite…the weekend looks great with mild weather for Opening Day. Highs may well be in the 70s with game-time temperatures near 70° dropping into the upper 50s by the end of the game.

Joe

 

 

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