Turning Up The Severe Potential
Much of the Spring Season has been a quiet one when it comes to severe weather. It has been a below average season for tornadoes as well, with only 18 preliminary reports coming in for March when the 3-year average is 87 and in April, there were only 83 preliminary reports of tornadoes where a 3-year average is 368. So far, the quiet trend has lingered into May with only 17 preliminary reports coming in for tornadoes. However, the weather turned dangerously severe on this past Wednesday (May 15th) when a preliminary estimated 16 tornadoes rolled through portions of northern Texas with the strongest being an EF-4 with winds around 180 MPH and was about half a mile wide.
The pattern is looking to stay active for the next few days with several days of back-to-back severe weather chances popping up, from the upper Midwest to the Southern Plains.
There was plenty of activity in the very early hours this Saturday morning with flashes of lightning and heavy downpours coming around the Twin Cities area in Minnesota. This suburb of Minneapolis, Minnetonka, was being lite up throughout youtube user weathrlver, journey. He is our very own weather producer, DJ, and he had said he had to pull over for a while because the rain was coming down at such a furious pace.
Speaking of rain, wow, did the St. Paul area see a lot of it! It rained heavily and plentifully across portions of Minnesota. A daily record was almost broken at the Minneapolis-St. Paul Airport this morning where almost 1.5″ of rain fell. The previous record was 1.57″ set back in 1892. Storms later on today might come along and add a few more drops into that rain gauge later on this evening. After the showers came and moved on, a hazy picture was left to be found and some rays of sunshine were seen popping through the cloud deck. If enough sunshine comes through, the temps will rise this afternoon and go beyond normal levels, into the mid 80s. It will feel very muggy with all that moisture left around and temps get up that high.
The CAPE or Convective Available Potential Energy, is a measure of much energy the atmosphere has to fire off severe thunderstorms. Here we show the “Thunderstorm Potential” available later on Sunday afternoon. The darker the colors, the higher the CAPE. There looks to be plenty of potential from central Oklahoma up into northern Illinois.
On Monday, that potential is still rather strong across the southern plains, and looks to be a little bit higher towards the Great Lakes.
The pattern in the jet stream is helping to make the severe potential strong this weekend and into the beginning of the work week. The jet is dipping down across the west and then bending back up towards the northern plains, across the mid-west, and riding up towards the northeast. It is that area right ahead of the bend in the jet stream where we could really see some strong storms fire up. The jet stream is the “river” of steering winds aloft in the upper atmosphere.
The dew points, the measure of the moisture in the atmosphere, is going to be on the plentiful side, as it is going to be flowing freely from the Gulf of Mexico, and up into the plain states. Dry air is going to slide down where the jet stream is dipping out in the west. The border of where the airmasses will be clashing is also where we could see storms fire up; right along the Dry Line.
Temperatures are going to be very warm ahead of the storm system, with highs in some spots approaching record levels. Across the central plains and into the mid-Mississippi River Valley, there could be temps riding up into the 80s and possible 90s. Back into the western areas, cool air is dropping down and temps will be running about 10-15° than normal.
There is a Moderate Risk zone highlighted in orange for Sunday. The slight risk zone covers roughly 9 states, just about all of the plain states.
On Sunday, that threat for severe storms shifts slightly eastward, encompassing more territory and another Moderate Risk zone is up once again. And tomorrow, there could be a higher chance for seeing widespread tornadoes.
By the time we begin the work week, the Slight Risk zone is extending from Michigan to Texas, covering just about 11 states and numerous big cities. Chicago, St. Louis, Kansas City, Oklahoma City and Dallas could all have to deal with large thunderstorms delivering hail, gusty winds, and isolated tornadoes.
Stay safe and stay tuned right here at WeatherNation for the latest information.
Meteorologist Addison Green (Twitter: @agreenWNTV)