Tuesday, February 28, 2017

March arrives like a lion - details on potential severe weather

As we close out what will likely be the warmest February on record, March appears to be coming in like a lion as severe weather potential exists mainly early on Wednesday morning (March 1).

A strong cold front will plow into a very warm, unstable, and moist airmass that resides across the eastern U.S. A rare (considering time of year and location) Moderate Risk (category 4 of 5) zone across the Midwest and Ohio Valley region, which stretches as far south as southern Missouri. Scattered supercells capable of producing tornadoes, very large hail, and damaging wind will be likely across this region this evening and into the overnight hours:

The severe weather outlook for Tuesday through 6am Wednesday. A Slight Risk (category 2 of 5) is in effect for the metro, primarily for the last few hour of this outlook period (wee hours Wednesday).

Behind those discrete supercells, a squall line will likely form along the front as it moves east overnight into Wednesday. That will lead to additional severe storms, more capable of damaging straight line wind, east of the Mississippi River on Wednesday:

The severe weather outlook for Wednesday, beginning at 6am. A Slight Risk (category 2 of 5) is in effect for the early portion of this outlook period. Storms should be east of the metro by 9-10am.

A preliminary look at hi-res simulated radar from the HRRR model valid at 6am Wednesday showing the approach of what might be the second line of storms to affect the metro early Wednesday morning. An extensive area of thunderstorms extends through the Ohio Valley into western PA. (WxBell)

Memphis-area storms

For the Memphis metro, most of the "discrete" supercells tonight will remain to our north. That is a good thing. A few thunderstorms will likely form in AR late this afternoon/early evening and move northeast, but will likely miss the metro to our northwest. We'll be keeping a close eye on this situation as they could produce large hail, damaging wind, and have the low potential for a tornado. Note that those are most likely in the Enhanced Risk (3 of 5). For at least the first half of the overnight period, we should remain dry, but strong south wind and high dewpoints (mid 60s) will keep the pump primed.

By the wee hours of the morning through rush hour, we will begin to see our severe weather risk ramp up as the cold front draws a little closer to our area. The possibility exists of one or more lines of strong to severe storms moving through between 3am-9am. These lines would bring the possibility of straight-line wind damage, perhaps some hail, and a low-end tornado risk. By mid-morning, the line(s) should be to our east and the threat of storms ends as wind shifts to the northwest and temperatures fall out of the 70° range.


To summarize, a few storms are possible, mainly northwest of the metro, early this evening, followed by a higher risk of storms from the wee hours of Wednesday morning until mid-morning. Damaging wind, hail, and possibly a tornado are all possible. We strongly suggest that you take the time review your severe weather action plan and make sure that you have multiple ways to receive notice of threatening weather while sleeping. These could include NOAA Weather Radio and a smartphone service like StormWatch+ in the MemphisWeather.net mobile app. Do NOT rely on hearing a tornado siren overnight. With wind blowing and potentially rain hitting the roof, you're asking for trouble if you hope that you hear a siren. We also encourage you to follow along on our social media channels for the latest information and nowcasting of any storms that affect the area.

Given that this week is also Severe Weather Awareness Week, it's perhaps ironic that severe storms could occur. However, it's also fortunate that this week is the one week of the year that we discount the StormWatch+ service in the MWN app! If you don't have a weather radio or can't get one, spend $5.99 (one-time upgrade in the app) and set up the locations you want to be alerted for. Here's a video that describes the setup (it's pretty straight-forward) and here's something you should read to make sure you receive severe weather notifications via our "wake-me-up" audio alerts while sleeping. The app only yells at you if a Tornado Warning (or Severe Thunderstorm Warning) is issued for your specific location.

Finally, on our Facebook page, we are giving away a NOAA Weather Radio this week courtesy of our partners at Midland Radio! Just find the pinned post at the top of the page to enter. #TeamMWN also will be presenting a severe weather preparedness video discussion on Thursday night at 8pm. Be sure to mark your calendar to watch, learn, and join in the conversation, as well as have another chance to win a weather radio!

Stay safe,

Erik Proseus
MWN Meteorologist

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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

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