Monday, June 15, 2015

More Flooding Rainfall Possible As Tropics Heat Up

If you have not had the chance to watch the video below, I highly recommend it for more specifics. As of Monday morning, I don't have much in the way of changes.  The track of the tropical low is key in determining where the axis of heaviest rainfall sets up.  At this time, it appears the track will go right over eastern Oklahoma which puts western Arkansas in a favorable position for heavy, tropical rainfall.  If this verifies, eastern Arkansas will see very little compared to the west.    Any deviation in the track of the system will change who gets the heaviest rainfall.  If the heaviest rainfall stays over eastern Oklahoma, this will still cause river flooding issues in Arkansas.

I will once again mention the threat for tornadoes.  Honestly, it's not high at all, but it's there.  Even a weak tropical system can spawn a brief tornado or two so that must be watched.  The favored locations for that will be eastern Oklahoma and western Arkansas.  That too is subject to change depending on the track.  These brief spin-ups usually occur along and just east of the center of low pressure at the surface.

Hungry for some spaghetti?  That's what this is called "spaghetti plots".  Each line represents a computer model and its forecast track.  There is remarkable consensus on a landfall in SE Texas, then a recurve through eastern OK into Missouri.  This puts Arkansas on the eastern side of the circulation which is always the wettest.  The exact track still has to be pinned down to determine who gets the heaviest rainfall.  There is the potential for a sharp rainfall gradient from west to east.

The Weather Prediction Center really indicates where the track of the low will be located and the heavy rainfall associated with it.  Some of the rainfall could exceed 7 inches over eastern OK and NW AR.  This will cause flooding and even river flooding along the Arkansas River downstream.  Notice eastern Arkansas will not see much compared to the west as the system is steered by a large ridge located over the SE United States.
The Sunday night run of the European shows the axis of heaviest rainfall a little more to the west.

The GFS from weatherbell.com shows the heavy rain over western and northern Arkansas.  You can see both models have the same idea, but differ on the exact placement of the heavy rainfall.  This is why the forecast will have to be fine tuned in the coming days.
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