Thursday, November 14, 2013

An early look at Sunday's chance of severe weather

The Mid-South has been quite chilly as of late with dry air, clear skies, and calm wind managing to drop temperatures into the 20's the past couple of nights. That diurnal cold trend ends tonight with increasing moisture/clouds and southerly winds. This change in the weather is important leading up to Sunday because thunderstorms are fueled by water vapor and the warm temperatures that accompany them. You can thank the Gulf of Mexico for potential severe weather by being so generous to supply plenty of moisture in a relatively short time frame. Lets take a look at some details.

Infrared satellite imagery valid at 2332z (5:32 PM CST).
Infrared satellite imagery reveals cloud cover surging toward the northeast from the western Gulf of Mexico. Observed dewpoints in eastern Texas and western Louisiana are in the 50's while Memphis is still hovering around 20 at the time of this post. Our dewpoints will increase rapidly overnight and will continue to increase as we approach Sunday.

The Weather Prediction Center's 60-hr forecast of fronts/pressure and weather, valid 00z Sunday (6:00 PM Saturday).
The above image, valid Saturday evening at 6PM, indicates the formation of a surface low pressure system. This low in eastern Colorado will provide the cold front responsible for a line of thunderstorms approaching the Mid-South the latter half of Sunday. But remember, without the days of building moisture the initiation of the thunderstorms would not be possible.

Perhaps the most important feature that we will keep an eye on will be the state of the atmosphere during the day on Sunday. Depending on many specifics, thunderstorm initiation could occur prior to the arrival of the line of storms on Sunday. If this is the case, this would be the period of time with the highest risk of severe weather. This is primarily due to the storms being in a more favorable, isolated environment. Tornadoes, large hail, and damaging winds are all a possibility if supercells are able to form ahead of the expected line of thunderstorms on Sunday.

The Storm Prediction Center is monitoring a large area from the Ohio Valley to the Mid-South for potential severe weather on Sunday.

With that said, now is the time to revisit your severe weather plans (we are in the heart of secondary severe weather season). As of now, you should be prepared for all types of severe weather for the entirety of Sunday. As we get closer, timing and storm mode will become more precise and of course we will pass that information on to you. Let us know if you have any questions regarding the potential severe weather Sunday!

--William Churchill (Social Media Intern)

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