Drought Report-Rain-Isaac Update

Posted on: 9:42 am, August 23, 2012, by , updated on: 01:34pm, August 23, 2012

drought

A lot to go over on this Thursday AM. Our rain chances will be the last thing I cover. So many interesting things related to our drought. I know it’s been awhile, but on average did you know that we should be getting about 1″ of rainfall per week? It’s been a couple of months since that happened. Yesterday in Las Vegas, they had their second biggest rain in their history with 1.65″. Their previous daily record was .23″. So then I decided to crunch some numbers. Since 6/22 I think, we’ve had about 1.3″ of rainfall. So based on yesterday Las Vegas has had more rain in one day than we’ve had in 2 months! For the month of August they’ve had 2.28″ of rain which is more than 3x’s what we’ve had here in KC! (.65″).

So it’s no wonder why we’re having all the issues we’re having. Since the flash drought started in April, we’re now close to 15″ below average since 4/1. The new drought report came out and aside from some expansion of some of the categories, hasn’t really changed much since last week. The thing is though, when you’re in an “exceptional” category, like most of us are in, it can’t get any worse from a “category” standpoint. Exceptional is the worse of the worse. Here is a breakdown for MO/KS.

Basically for MO…99% is now in an “extreme” or higher category drought and on the KS side 96% is in the “extreme” or higher drought. The most noticeable change was an expansion of the “extreme” drought through NW MO. By the way, to our south, this is a big issue for AR as well.

While the “extreme” category is “only” 74%, the “exceptional” category is a whooping 45%. So this drought is really gripping more than just MO/KS

What we need is a good tropical system to come up and soak the region. While doubtful, there is a system that we’re watching to affect the SE part of the country. That would be Isaac with winds as of this writing at around 40 MPH. While looking decent on the satellite images, there is still much disorganization with the storm, with multiple centers and clusters of storms rotating around.

At this point, because the storm isn’t well organized the wind fields are not terribly large.

The future of Isaac, still appears to be towards FL, however where the center of the storm goes and how strong it is is still uncertain. There is a lot of terrain the storm may be going over between where it is now and where it might be on Monday.

Going over Hispaniola is never a good thing for struggling systems, for the system or for that island. Then there is the interaction with Cuba, then it comes back into the water int eh FL Straits. How the system will be able to constantly cycle up and down with the various land interactions is still up in the air but usually these things don’t like all the land interactions at all, and it’s very possible this storm struggles quite a bit for most of it’s life. There may be periods of decent intensification, there is a LOT of warm water in the Gulf region, but how large the wind field gets to actually do damage on the US mainland is still a question as well. Here is a look at a multitude of computer forecasts and you can see why the Hurricane Center is pretty much sticking to the average off all these positions.

OK so I started the blog talking rain, now let’s finish the blog talking rainfall. 1st the good news, the air is going to get more moist. That is one of many things we’ve been lacking for awhile now. The water content of the atmosphere should jump to 1-2″ over the next several days. That’s a good thing because as the flow flattens out and disturbances come out of the monsoonal flow across the SW and the Rockies and move across KS, they actually will have some moisture in the air to work with to sustain themselves. Another good thing for rain is that there should be some wind in the lower part of the atmosphere from the S/SW. This low level jetstream should also help sustain the systems and even generate additional rains as the whole entity moves eastwards. Finally the surface moisture should increase rather dramatically on Saturday. That means dewpoints will pop into the 60s again, we’ve been in the lower 40s in the PM hours lately. That too should help the cause. So we do have certain things working for us over the next 3 days that we haven’t had recently. No the issue is getting these disturbances to track correctly for us to maximize all this potential. That could be trickier, and the modeling really won’t have a clue to the proper placement. They will show potential but heavy rain targets will fluctuate from run to run and relying on a specific run to justify a forecast will be daring to say the least. We also have to remember that even IF we can manage 1″ of rain…let’s remember that is our average week of rainfall. So while it would be the best rain in 2 months, it’s just a average late August worth of rainfall.

At this point I’m remembering all to well the systems a couple of weeks ago that gave us great looking swirls of disturbances on the satellite images but really generated “minor” rainfall amounts, despite the fact that it did rain over a few days. I’m still not comfortable forecasting amounts for the weekend. I am comfortable in saying there should be a lot more cloud cover dropping highs into the 80s, and depending on the timing of the rain, maybe only in the 70s for awhile. Our microcast model late last night painted a 2-3+” rain for the I-35 corridor, I think the chance of that happening is slim at this point.

Looking at the 1st bits of new data this AM, it seems to confirm what I forecasted yesterday that the better chances of decent rainfall would be to the NW of KC, up towards NW MO and NE KS. Again this could change and there could be a southwards shift, but until these things actually develop and move closer, I won’t be confident that we’ll get anything more than minor amounts (under 1/2″), which is an average Summer would be great, but in a “exceptional” drought is really a pittance. it should be noted that the PM models are rather bullish with the rainfall, essentially giving most of the region 1-2″ of rainfall. Their doing it in different ways and over the course of different times but at least their showing some potential. We’ll see and hope they’re right!

As for timing the rain, well there actually may be some scattered showers in the region tomorrow, then the better chances are across NW MO and NE KS on SAT, with some trailing metro activity during the day possible, but the “heavier” rainfall is perhaps slated for SAT night into SUN AM.

To me this is not a “washout” weekend. there will be LOTS of dry times to do things outdoors I think at this point. You may be dodging some rainfall however at various times.

Joe

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