Monday, July 20, 2009

Rare July system

Well we have a pretty interesting and uncommon mid to late July storm system developing over us right now. It is almost 2:00 AM and I waited so long to post today, because this more of a nowcasting event as the models arent doing such a great job with this system and the storm is developing right over us, so things are changing all the time. Take a look at the current surface analysis map:

You can see the storm over northern Oklahoma and southern Kansas developing and the area of rain across southeastern Kansas and western Missouri in association with it. This storm will continue to organize as it pushes it way toward central Missouri. As a result, the rain will track out of Kansas and push into Missouri. Here is 12 hour forecast surface analysis map valid 2:PM Tuesday:

This is showing this happening with the rain spreading in across central Missouri. I am not expecting any severe thunderstorms with this, but any embedded thunderstorms could have a lot of lightning. If I am not expecting severe weather, why is this a rare storm system? Well there are many answers to that question.

In the Summer time, we commonly get complexes of thunderstorms that develop in association to small disturbences tracking across the area called MCS's or Mesoscale Convective Systems. These can commonly contain strong storms producing hail and damaging straight line and/or microburst winds. This is not a small disturbence, but a developing strong storm system. This is also unique as it is forming through many layers of the atmosphere. Another factor is we just had 3 straight days of record breaking low temperatures. There are many many more things I could mention as to why this is a rare storm.

So how is it forming? Take a look at the current 500 mb forecast map:

We are experiencing a Diffluent flow aloft as the air is strongly diverging. When you have a set up like this, the air at the surface must rise significantly. Take a look at the map below:

This map above is showing the current 700 mb Vertical Velocity, and it shows the air rising in our area. With this lifting mechenism, the storm is forming, but it isnt moving very fast and with all the rain in place, the set up is there for some flooding problems. I think areas in eastern Kansas and western Missouri have the potential to see 1 to 3 inches with locally up to 5 inches possible. The least likely spot to get in on the heavy rain will be north central Missouri and points east.

I will have a new blog in the morning.

Alex Pickman


Post a Comment

Subscribe to Post Comments [Atom]

<< Home