Tuesday, April 9, 2013

Update on potential severe weather Wednesday night

Severe weather remains a concern Wednesday night for much of the area.  Though models are getting very close to agreeing on the main concepts, fine scale details are still to be determined.  Below is a probability map showing the chance of severe weather on Wednesday and Wednesday night, as issued by the Storm Prediction Center.  

The entire region continues to be under a Slight Risk of severe weather, though the probability map highlights those areas that are more likely to see severe storms.  The eastern half of AR right up to the Mississippi River, southeast MO, and extreme southern IL are under a 45% risk area, meaning there is nearly a 50/50 chance that severe weather could occur within 25 miles of people living in that region.  The west TN and northwest MS portions of the metro have a 30%+ risk of seeing severe weather within 25 miles.  This is, of course, subject to change as the new outlooks are posted beginning early Wednesday morning.

As for timing and severe weather risks, the models have come to a consensus that the cold front will move through the metro sometime between about midnight and 6am Thursday.  The solutions vary from 1am-4am along the river.  Just ahead of the cold front, we expect to see a squall line (or QLCS - quasi-linear convective system) move through.  This line will bring the primary severe weather threat, which will be a period of strong to possibly damaging thunderstorm wind of 40-60 mph+. Some hail is also possible with the line.  It is also possible, especially in the 45% risk area, to have brief "spin-up" tornadoes embedded within the line.  These types of QLCS tornadoes generally last just minutes and are typically weak (although 80-100 mph "weak" tornadoes in the right place will definitely do some damage).

Ahead of the line, scattered showers and thunderstorms are possible beginning during the afternoon and lasting into the evening hours. Severe weather is generally not expected with these, although brief gusty wind and small hail are possible.  Following the line, thunder will likely continue to rumble deep into the night, but the main threat behind the line will be torrential rain that could produce minor flash flooding. Rain will continue into the morning hours Thursday, tapering off by afternoon, and produce rainfall totals of upwards of 2-3" for the event.

Rainfall totals from the upcoming event could total nearly 3" in the metro

Mid-Southerners should be prepared for the possibility of severe weather, mainly high wind, during the overnight hours on Wednesday.  This could include the chance of power outages.  Have multiple ways of getting severe weather information at night, even if you are asleep. NOAA Weather Radios and smartphone apps are our top 2 suggestions.  Notice outdoor warning sirens are NOT a preferred method.  You likely won't hear them if the wind is howling and rain is pouring down, plus they won't go off for 60+ mph straight-line wind from a severe thunderstorm, only tornado warnings.  Our recommendation for a smartphone app is the MemphisWeather.net app with StormWatch+, which will alert you (and wake you!), but only if your location is threatened by severe weather.  It's street level alerts in the palm of your hand!

MWN will provide overnight coverage of the storms on our social networks listed below with our highly-acclaimed wall-to-wall severe weather nowcasting as long as there is a threat of severe storms.

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:

DanTheCigarMan said...

Thanks Eric for keeping us posted!