Monday, January 28, 2013

First major severe weather event of 2013 possible Tuesday night in the Mid-South

We'll have more detail later on as we continue to examine model data, but the first large-scale severe weather event of 2013 could unfold on Tuesday into Tuesday night from the ArkLaTex into the Lower Mississippi Valley, with the potential for severe storms as far north as central IL/IN.

For the first time in over a year (January 22, 2012), the Memphis metro has been included in a Moderate Risk of severe storms for the overnight period Tuesday night.  The Storm Prediction Center indicates that there is a 45% chance of severe weather (wind in excess of 60 mph, 1" or larger hail, or tornadoes) from Memphis south and west into southeast AR, northern LA, and western MS.  In addition, the possibility of "significant" severe weather is at least 10%.  It is uncommon for these sorts of probabilities to be issued on a "day 2" outlook and raises red flags.  (The last Moderate Risk on January 22, 2012 was a slight risk on day 2 and not upgraded until the day of the event.)

The first Moderate Risk area of 2013 includes the Memphis metro. This is valid Tuesday into Tuesday night. Storms are expected in the metro on Tuesday night.

Probabilities of severe weather with Tuesday's severe weather event. A "45% hatched"area for the metro means that there is a 45% chance of severe weather within 25 miles of any location in the area and a 10% of greater probability of that severe weather being "significant" (very high wind or large tornadoes).

Associated threats and timing

There are still model differences that have to be ironed out, including exactly when to expect the severe weather in the metro, but we do know that it will be after dark and most likely in the 9pm-3am time frame Tuesday night. All modes of severe weather are possible with the #1 threat being a squall line with excessive and damaging wind of 60-80 mph.  It appears that wind just a couple thousand feet off the ground will approach, or possibly exceed, 75 mph.  In convective situations, it is not hard for these winds to be shoved to the ground, producing widespread damage.

There will also be a threat for tornadoes with this event, though the risk is lower than damaging wind. Typically in squall line events such as this, tornadoes are brief and weak, but a "weak" EF-0 to EF-1 tornado can bring wind in excess of 100 mph. They are typically very hard to pinpoint very long before they occur because they are fleeting.  Any storms that form during the evening hours ahead of the main line would pose a higher risk of tornadoes.

Call to action

Do not wait until a warning is issued to prepare for this potential severe weather event. Prepare today and tomorrow before the threat is on us, including having at least one way of receiving warning information while you sleep. That should NOT include expecting to hear outdoor warning sirens.  With wind blowing and rain pouring while you sleep, you will likely NOT hear them.  Make sure your NOAA Weather Radio has fresh batteries. Get more safety tips from MWN here.

The best way to get severe weather info if you have a smartphone though is to download a weather warning app that will A) alert you for Severe Thunderstorm and Tornado Warnings, B) wake you up if you are asleep, and C) preferably warn you only if your location is under the warning.  We don't care which one you get as long as it meets A & B, and preferably C.  However, we highly recommend the mobile app for iPhone and Android. The StormWatch+ feature within MWN meets all three criteria above, is reasonably priced, and the app contains a ton of other content that will keep you updated any time you need good, reliable, LOCAL information that you won't find on a "national" app produced by an out-of-town provider with no customer support. Download the app today and get used to it's features.  You'll be glad you did if the power goes out and the storms are overhead!

We'll have more information later today and tomorrow.  Be prepared, not scared!

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