Yesterday we discussed Invest 99L and its chances for development.

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Checking in our disturbance this afternoon, we see that 99L is trying very hard to organize. It’s displaying quite a bit of convection near its center and has hints of a low-level center. Development chances have been bumped up to 60%.

At the end of yesterday’s blog, I mentioned that this disturbance would impact weather in the US down the line regardless of development. How will it accomplish that?

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Through it’s moisture, of course.

Toward the end of the weekend/into early next week, a sluggish boundary draped over a decent portion of the southern 1/3 or so of the US will focus 99L’s northward-moving moisture over some the southern Plains states. This could be a prolonged event, as waves of moisture via the southerly flow repeatedly come up against this boundary.

We know from past tweets and blog discussions that this part of the country has been so very dry over the past few months. So, days of rain sounds like a wonderful thing. Hold on, not so fast.

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While yes, it will be beneficial in the long run, we need to remember that the ground is parched. And, not only is it parched, but it’s been sunbaked by the relentless heat this region has experienced this summer.

By now you should be picturing that cracked ground you see in movies when filmmakers are trying to suggest it’s extremely dry. Do we think ground like this will readily absorb rainfall? Well, that completely depends on the rate of rainfall.

While a gentle rain can be slowly absorbed, heavy tropical downpours pummeling the dry ground won’t allow time to absorb the sudden influx of water before translating to flash flooding. So, days of heavy rainfall can pose a serious flash flooding threat.

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A multi-day stalled boundary combined with very dry ground, an influx of tropical moisture, the potential for training storms, and  7 day estimated rainfall totals that look like this (above) should start sounding some alarms regarding flash flooding potential. Again, this rain is absolutely needed, but perhaps it would be best if it didn’t all come at once, not that the atmosphere plans on giving us a choice.

If you’re in this region and your location has been vulnerable to flooding in the past, now is the time to start planning in case you’re faced with an issue.

We’ll keep you updated on rainfall and flooding potential as we move into next week both here in the blog and in our Twitter feeds!