Friday, April 25, 2014

Multi-day severe weather outbreak possible Sunday-Tuesday

A couple of hours of rain and storms and very few warnings were all that came of last night's severe weather risk and Thunderstorm Watch, but at least everything outdoors got a good pollen-washing!

All attention now turns to what may be a significant multi-day severe weather outbreak that begins in the Plains tomorrow, but then threatens the Mid-South and Mississippi Valley into the Southeast Sunday through Tuesday.  The map below identifies the areas that the Storm Prediction Center believes, at this time, are worth monitoring and could potentially see an outbreak of severe storms.

The left panel shows the severe weather risk area for Sunday. The Memphis metro is in a Slight Risk with the greatest threat from far eastern TX/OK into AR. Models are indicating storms will break out to our west during the day Sunday and move east towards the Mid-South, arriving sometime during the afternoon or evening. The highest risk of large hail, damaging wind, and tornadoes will be west of the river, but the metro will be in a favorable area for severe weather, which could include any mode - hail, wind, or tornadoes, as well as heavy rain and lightning - and last into at least the first half of the night.

The right panel above shows the risk area for Monday (red) and Tuesday (purple) with a large overlapping area for both days, including the Mid-South. Monday is our day of chief concern when the severe weather risk is centered over the region. Again, afternoon and evening are when the instability provided by the sun's warmth will be maximized, so the strongest storms would be most likely during those hours, however storms could be possible anytime from morning into the overnight. Until we get closer, timing storms is nearly impossible. Once again, all threats are possible, including large hail, high wind, and tornadoes. In addition, flash flooding could become a threat Monday as well due to the multiple rounds of storms.

By Tuesday (purple in the right panel above), the slow moving upper level system will push a bit further east and the actual cold front that will bring the severe weather threat to an end will move through. There is considerable uncertainty five days out as to when that happens. Until it does, more storms will be likely, especially during peak heating hours. We believe that threat is maximized east of the Mississippi River in TN, MS, and AL, but depending on the progress of the front, the west side of the threat area is hard to define. For now, SPC has the entire Mid-South outlooked for possible severe storms.

It's a beautiful day today and Saturday will be warmer and more humid but still a very nice day. Don't wait until Sunday to prepare for the likelihood of severe weather. Get your severe weather supplies/kits ready before Sunday. Know where your severe weather shelter will be wherever you will be Sunday through Tuesday. Check the batteries in your flashlights and weather radios and get StormWatch+ in your MWN mobile app set up ahead of time. (Don't have MWN with StormWatch+ for severe weather notifications that will wake you up if necessary? Get it here.) Secure any outdoor items you don't want damaged by wind or hail. In sum, take the time on good weather days to prepare for the bad!

This is not written to hype the event or preach doom and gloom, but we honestly haven't seen the threat of severe weather over multiple days in a couple of years (since the awful spring of 2011) in this area of the country. I'm not saying this is another April 2011 event, but overall, severe weather has been fairly benign for with a few exceptions since then. Keep it here for more updates as we get further information and follow us on social media for the latest as well.

Be prepared, not scared.

Erik Proseus
MWN Meteorologist

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