Severe weather risk – Update for Sunday, November 17

The southeastern U.S. is in the heart of it’s secondary severe weather season, but it appears the Midwest, Ohio Valley, and parts of the Great Lakes will have the greatest chance of severe storms on Sunday.  However, that doesn’t mean we’re completely out of the woods in the Mid-South.  Overall, my confidence in severe storms in this area, particularly tornadoes, is somewhat low for Sunday.  Here’s how I expect it to unfold.

Severe weather risk zones for Sunday. The greatest threat is well north of the Mid-South

Warm, moist air has infiltrated the Mid-South on southerly, occasionally gusty, wind today, as temps have climbed well into the 60s.  With increasing wind and moisture overnight, don’t look for temperatures to fall much if at all, remaining in the 60s with wind gusts to 20-25 mph. Our first round of thunderstorms is also expected early Sunday morning, probably after 3am, in the metro.  These storms are NOT expected to be severe, but could wake you up overnight and might produce strong wind to 40 mph or so, but not quite to severe criteria (58 mph), or perhaps small hail.

Hi-res NAM model showing “forecast radar” at 4am Sunday. Scattered storms could be in the area by then. Don’t take this graphic literally with regard to exact storm location.

Showers and storms will be ongoing into the mid-morning hours or so before tapering off as the first impulse moves out of the region.  During the day, very strong southerly wind, with gusts to 35-40 mph (Wind Advisory in effect), will push temperatures up to near 80 degrees and a little sun is possible in the afternoon.  However, even given increased instability due to warming temperatures, high moisture content, and a little sun, computer models really do not develop additional storms until the cold front approaches.  Timing of the front is around 6pm, give or take an hour or two.  The same model shown above develops a line of storms along the front pretty much right over the metro (see below).  These storms could bring a round of near-severe wind gusts (50-60 mph), though the tornado risk will be fairly low with these storms. Once the front moves through, skies will clear quickly and the storm threat disappears.

Hi-res NAM model (as above) showing “forecast radar” at 6pm Sunday. A line of storms will likely form along the cold front. Again, exact storm timing is not certain, but should be close to this time.

To recap: scattered storms and showers are likely after 3am Sunday until mid-morning, followed by a break in the action and quickly warming temperatures along with windy conditions. A few more storms are possible by late afternoon but the last round of storms will occur along the cold front in the early evening.  The severe weather threat is not zero (a Slight Risk is in effect), but does not seem particularly high.  Further north, a much more significant threat is unfolding.

Consider where you will be during potential storms and be sure you have a way to get severe weather watches and warnings if they are issued.  We highly recommend the MWN mobile app with StormWatch+.  Links are provided below.  We’ll provide nowcasting coverage throughout the day tomorrow to keep you informed via our social channels, also below.

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