Leap Day update on Super Tuesday thunderstorms

In yesterday's blog about the weather this week, we discussed the probability of severe storms on Tuesday, indicating that the likelihood of severe weather was rather low. While this update isn't a complete "180," today's forecast data caused me to pause for a closer look. First let me say that another Super Tuesday severe weather outbreak (i.e., 2008) is NOT expected. However, a few severe storms cannot be ruled out.

Here are the two graphics worth sharing today. First our impact graphic produced at mid-day that contains the high-level overview:

...and next a reminder of what the various risk levels mean. For now, we're in a category 2 of 5 (Slight Risk) for Tuesday, meaning some storms could become severe, but not a lot.

Description of the outlook categories used by SPC. Click for larger image.

The details are that a strong upper level system and associated cold front will be moving through the region. These systems will tap into increasing levels of moisture and modest instability. There will also be a good deal of wind energy with this system, at the surface and especially aloft. These factors will combine to produce a large area of rain and thunderstorms, starting early Tuesday as noted above, and moving east of the metro by mid-afternoon. A few morning storms could become severe with damaging wind the primary threat. The wind energy will be borderline for producing tornadoes, so we'll have to keep a close eye out. In addition, any storms will be capable of brief heavy downpours and the wind will be blowing strong until after the front has passed in the mid-afternoon.

Tomorrow is Super Tuesday, which means many of you will be voting (we highly recommend it, but please go through the line once, even if you really like your candidate...).

While there may be some showers around during the pre-work voting hours, the best chance of strong storms will be after rush hour through the lunch hour. By the afternoon rush hour, it'll be over. If you have a choice when to vote, we recommend getting off work a little early and doing it in the late afternoon/early evening. Then expect a wait, because most everyone else will wait too.

Regarding preparation, we suggest that as well. We'll even help you with it. Tonight at 8:30pm, live via the magic of video chat, we'll convene a panel of guests to talk about severe weather preparation, and maybe a controversial topic or two, because it's Severe Weather Awareness Week. We may even have a giveaway of some sort, because we appreciate all of you. You can participate by watching on YouTube (desktop or mobile) or on our Hangout webpage and asking your questions on Twitter using the #wxchat tag or in the chat we have set up for you on the Hangout page linked. I hope you'll join us!

Erik Proseus
MWN Meteorologist

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Warm weekend gives way to spring rain. Is winter over?

The past week ended cool, but just like last weekend, beautiful spring weather arrived just in time for the weekend! We've certainly enjoyed temperatures in the 60s the past couple days with a breezy south wind.

Early week forecast

A weak front arrives tonight, bringing a slight chance of showers mainly in the late evening hours, before stalling and basically washing out over north Mississippi on Monday. Temperatures remain above normal tonight in the mid to upper 40s then rise well back into the 60s on Monday with sky conditions no worse than partly cloudy on average.

High-resolution model simulated reflectivity indicates a few showers will pass through early this evening ahead of a cold front. Graphic courtesy WxBell.

The next major weather system arrives on Tuesday. Strong southerly wind help to "reload" the atmosphere, but March won't exactly come in like a ferocious, hungry lion. Low pressure going by to our north will push a front into the region Tuesday afternoon. Some instability will be available and moisture levels will be high for this time of year, meaning thunderstorms are probable, but wind shear will be at moderate levels so severe weather is expected to be limited at best.

Tuesday afternoon instability values, as measured by Convective Available Potential Energy (CAPE), will be sufficient for thunder, but the upper level dynamics will be insufficient for much severe weather. Graphic courtesy WxBell.

The severe weather risk Tuesday is Marginal (category 1 of 5), indicating no widespread severe storms are anticipated. A few storms could have gusty wind. 

With the high atmospheric moisture content (about two times normal for early March), rainfall could be heavy on Tuesday though, even though it won't be prolonged. Some areas could see up to an inch during the afternoon and early evening hours.

Total precipitation early this week could be near 1", especially across northern portions of the Mid-South, according to the NWS. Graphic courtesy WxBell.

Extended forecast

Following the front, a couple of days of cool weather is anticipated with another decent chance of rain on Thursday as yet another low pressure system moves through the region. The good news is that the weekend trend continues with temperatures rebounding back towards the 60s by the first weekend in March. This is a trend I certainly don't mind!

OK, so is winter over?

This is the question I've been getting of late. Last year, our biggest snow storm of the year came on March 4-5. Given that no snow is expected for the first week in March, we'll be back in the 60s next weekend, and the week 2 outlook for the second week in March forecasts above normal temperatures (as average highs climb close to 60°), I am fairly confident that measurable snowfall is done for this year. That doesn't mean we won't still see a cold snap, more frost, or even a sub-freezing low over the next couple of weeks, as that is possible well into March, but chances of any more snow are dropping by the day. With one near-miss of a big snow storm, this winter will go down with very little measurable snow in a strong El Nino season.

There is a high probability that temperatures will be above normal across much of the eastern U.S. for the second week of March according to NOAA.

Severe Weather Awareness Week

This week is Severe Weather Awareness Week in Tennessee. Check out our SWAW website for details on topics that will be covered. We'll also have a few giveaways this week and host a preparedness chat Monday night at 8:30pm via Google+ Hangout. Check out our social media feeds for the latest details.

Erik Proseus
MWN Meteorologist

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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 StormWatch+ severe weather alerts!