Tuesday, January 29, 2013

Severe storms likely in the metro tonight - details from MWN

The Memphis metropolitan area could experience part of the first major severe weather outbreak of 2013 tonight as a very potent storm system plows into a moist, warm, highly-sheared, and somewhat unstable atmosphere. The "somewhat unstable" part of the equation is the only thing that is inhibiting in any way.  Wind at the surface and aloft is more than sufficient to produce rotating storms, which means they will be capable of producing severe wind damage and possibly tornadoes.  Of course, a 75-degree January day is always the first clue to something else on the horizon!  Let's cut to the chase...

What we expect

Scattered storms are expected to form and/or move into the Mid-South from the west during the late evening, most likely after 8-9pm.  Some of these cells will likely form into one or more "mini-lines" of storms as they race northeast at 50-60 mph.  This is the more uncertain part of the forecast.  There is a "lid" or cap on the atmosphere this afternoon, keeping storms from forming.  If this cap is not broken before the main line gets here, these scattered storms may NOT form.  We expect to see something - we just don't know the degree to which these storms will form and how strong they may get.

However, much more certain is that a squall line will be moving across Arkansas during the late evening hours and will move through the metro probably between midnight and 2am.  The line will also be moving rapidly east and will be followed by a period of heavy rain and embedded thunderstorms.  Most of the rain should be gone from the metro by sunrise.

For a complete forecast, including what to expect in the next 7 days, click here.

Primary threats

In any storms that form ahead of the main squall line, all forms of severe weather will be possible, including damaging wind in excess of 60 mph, large hail, and tornadoes.  In the squall line, the most likely form of severe weather will be 60-80 mph straight-line wind and brief "spin-up" tornadoes that can occasionally form within the line, as well as hail. Any storms behind the line are not expected to be severe, but heavy rain will be likely for a few hours after the squall line (which will also bring torrential rain).  Total rainfall amounts could exceed 1-2" in a short period of time and flash flooding is possible, though not particularly likely due to the fast movement of the storms.

Severe weather risk maps for tonight. For tornadoes, wind, and hail, the probabilites indicate that chance of that phenomena occurring within 25 miles of any point.  Memphis has a 15% chance of a tornado, 45% chance of damaging wind (60 mph+), and 15% chance of 1" or larger hail.  The hatched areas for tornadoes and wind indicate there is a 10% or greater chance of an EF-2+ tornado or 75 mph wind within 25 miles of Memphis.

Call to action

Do not wait until a warning is issued to prepare for severe weather. Prepare NOW 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.  They are called outdoor sirens for a reason (it's not because they are located outdoors).

  • Make sure your NOAA Weather Radio has fresh batteries (despite earlier issues with Weather Radio, they are fully functional at this time)
  • Have your cell phone charged in case the power goes out.
  • Have flashlights, candles, or other portable light sources ready
  • Place shoes by your bed so you can slip them on if you need to take shelter
  • Clear out your "safe place" in case a Tornado Warning is issued - downstairs, away from windows, preferably a small enclosed area like a closet or bathroom, or your storm shelter
  • In your safe place, have flashlights and extra batteries and something to do to wait out the storm.  If you have kids, also have shoes for them, bicycle helmets (for flying debris if God forbid something happens), something to occupy them, and maybe a snack and water or a drink.

Smartphone apps

The best way to get severe weather info if you have a smartphone 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 and B, and preferably C. However, we highly recommend the MemphisWeather.net 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 and get used to it's features. You'll be glad you did if the power goes out and storms are overhead!

App note: For iPhone/iPad users, to hear the wake-me-up feature of StormWatch+, do NOT silence your phone. Apple does not allow sound from push notifications when a device is silenced.  For Android users, push notification sounds will sound if your device is silenced.

This is a situation that should not be taken lightly.  We have not been under a threat of this magnitude since last January.  IF a Tornado Warning is issued for your home and you have children asleep, don't panic.  Wake them and calmly head to your safe place. A reassuring voice and words go a long way to keeping everyone calm.

We'll provide continuous coverage of the storms via Facebook and Twitter (links below) tonight as long as there is a threat. We won't rest, so that you can!

Remember: be prepared, not scared!

Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring a fresh new interface and StormWatch+ severe weather alerts!

1 comment:

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