Sunday, January 8, 2012

Heavy Rainfall and Severe Weather Update - Southern Plains / Gulf Coast for Early Week...

Earlier this morning I made an update concerning the winter weather aspects of the upper-level low pressure system that is currently organizing and moving out over the southwest U.S. The purpose of this post is to give an update on the potential for heavy rainfall and severe thunderstorm development in association with the same system over the next few days...

At mid-afternoon the center of upper-level low pressure was organizing out over the southwest, along the Mexico border with Arizona and New Mexico:

The system will move out toward the East overnight tonight and into Monday, with rain and thunderstorm development likely to become widespread ahead of the system across the Southern Plains.  Some of the rainfall will become heavy at times, particularly across the eastern one-half of Texas into Louisiana on Monday and into Tuesday.

The latest rainfall forecast from the HPC is calling for widespread amounts in excess of 1 inch extending from central into eastern Texas and much of western and northern Louisiana.  The rainfall forecast image below is valid for the period from 6pm CST today through 6pm CST Monday:

The threat for widespread heavier rains will shift Eastward into Tuesday...with the following image valid 6pm CST Monday through 6pm CST Tuesday:

...and will extend across much of the remainder of the Southeast by Wednesday:

In addition to the possibility of widespread, locally heavy rainfall, there will also be a threat of severe weather in association with this system on Monday, Tuesday and Wednesday.

Strong, gusty surface winds and marginally severe hail (mainly less than 1 inch in diameter) will be the main threats from any severe storms that form.

Isolated tornado development also cannot be ruled out.  In all honesty, the wind profile from the surface into the middle levels of the atmosphere will be very favorable for tornado development, especially on Tuesday.  It's the fact that the low-levels of the atmosphere will be unable to become very unstable (due to widespread cloudiness, rain and relatively cool temperatures) that will limit the threat of widespread tornado development.

The threat of severe weather will be the lowest on Monday, in an area extending across far southeast Texas and into much of Louisiana, generally within the brown shaded area on the image below:

A greater threat of severe weather, including a higher risk of isolated tornadoes, will exist on Tuesday across portions of the Deep South and lower Mississippi River Valley:

By Wednesday, the threat will shift rapidly Eastward, reaching the Carolinas and into far southern Virginia by afternoon.  The greatest risk of severe weather by that time is expected to exist inside of the red shaded areas on the image below (which has been updated slightly since my original post yesterday):

Folks living across the severe weather threat areas for tomorrow through Wednesday should remain alert and listen for later forecasts and possible warnings regarding the potential for severe weather.

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Shamrock said...

Rob, I am noticing the tornado warnings for parts of Eastern Texas right now...I can't recall if that's your area-something tells me I remember you being more South. I hope this is the case. Be safe if it is you.

Rob White said...


Thanks for your concern. We're just getting much needed rain here in my neck of the woods. The few severe storms that have taken place so far have been further East, near Houston.

Thanks again, and happy new year!