So far this year the severe weather season has been rather quiet, but big changes are ahead as we track what will likely be a multi-day severe weather outbreak for a large area of real estate in the Central US.
The risk for severe weather will begin on Sunday. The Storm Prediction Center locates about 1.5 million people in the “marginal” risk zone for severe storms, which stretches from southeastern Montana and southwestern North Dakota southward through the Mexican border in West Texas. The trough of low pressure, which will be the large-scale instigator for this week’s severe threat, will begin to dig into the Western US, so the thunderstorm activity will not be as widespread on Sunday in comparison to the middle of the week because the trough is still moving into the West. Once it centered its axis towards the Four Corners States, the threat for strong storms will ramp up. So on Sunday, storms will develop during the late-afternoon into the early-evening hours in the areas where severe storms are possible. These storms will be very scattered, if not isolated. Very spotty showers and storms are also possible farther east in the western Midwest region. Based on the atmospheric dynamics, small hail and damaging winds will be the main factors prevalent with these storms, but there is definitely a tornado risk, especially in the Northern Plains where the jet stream winds punch into that area. These storms will then die down and dissipate early-Monday morning, while showers and storms develop over North Dakota and head into Canada at around daybreak.
On Monday, the threat for severe storms will increase. Over 5 million people will be at risk, including about 2.5 million who are under a “slight” risk for severe storms, as noted by the Storm Prediction Center. In the morning, there will be a batch of rain with embedded thunder over central Minnesota that will track toward the western part of Lake Superior. There will also be a few spotty showers and storms further south and east in portions of Wisconsin and Iowa. Now in the afternoon, we’ll see a widespread batch of rain form in the Dakotas. These showers will not be too severe. The severe storms are expected to form in central Nebraska, where there will be a large line of storms. This line will contain damaging winds and large hail. The tornado threat will be on the low side due to the uni-directional winds in all levels of the atmosphere. Further south, isolated storms may develop in the western Southern Plains. Also a line of storms is expected to develop and move east through central Oklahoma. Overnight Monday, the line of storms will track east while weakening and becoming a bit more scattered toward Iowa and Minnesota. Additional showers may develop in Nebraska and southern South Dakota behind these storms.
On Tuesday, the severe weather risk will persist, particularly across the Central Plains this time. In the morning, scattered showers and storms will be found in parts of the Northern Plains and Upper Midwest. Then into the afternoon and evening hours, the severe storm risk will ramp up as the instability increases to the south. A line of heavy thunderstorms may develop from southern Minnesota through Iowa and into eastern Nebraska. Storms will then become more spotty to the south of there from Kansas through Texas.
The tornado threat will be higher on Tuesday, especially the further south you go. If any storms form in eastern Kansas and Oklahoma in particular, these storms will likely spin and may produce tornadoes. The reason for this is because of a very strong, low-level jet at about 5000 feet with winds up to 60 mph coming out from the south while the jet stream winds come out from the west at up to 75 mph. This entire severe weather risk zone will also be hot and humid with temperatures in the 80s and dew points in 50s and 60s, which is conducive for the formation and persistence of strong storms. This day will definitely be more active than Sunday and Monday, and one of this main reasons for this is because there will be much more moisture. The air will be moist enough for some storms to form on Sunday and Monday, but definitely not enough for widespread thunderstorms, unlike on Tuesday and Wednesday.
Then overnight Tuesday, most of the spotty storms will dissipate in the Southern Plains while the showers and thunderstorms, which will be very heavy for some, continue from northeastern Kansas through Wisconsin.
That leads us to Wednesday, which will be another big day for severe weather as the low-level jet speeds and instability, or CAPE values, peak in value. This severe weather threat will be centered around centered and eastern Kansas and Oklahoma, which happens to be the heart of Tornado Alley. These are also the two states that have not seen a tornado at all through April, which is unprecedented. In the morning hours of Wednesday, it will be a messy radar picture with spotty showers and thunderstorms spanning from the midsection of Texas through the Central Plains and into portions of the Midwest. Then as the setup becomes more organized, storms will fire up and strengthening along the dry line from Kansas through Texas. Scattered showers and storms will also form ahead of the warm front from the Central Plains through the Upper Midwest.
This set up will not be perfect for tornadoes, but it will definitely be conducive for them to form. The low-level jet will be even stronger with speeds up to 70 mph out from the south while winds at the jet stream level come out from the southwest up to 80 mph. There will be some spin in the atmosphere, but a 90 degree shift in the wind direction opposed to a 45 degree shift would be more favorable for tornadoes. There will still be large hail and damaging winds that will accompany these storms, however, which will make these storms very dangerous.
The severe weather threat will continue throughout Wednesday night. Rounds of rain and thunderstorms ahead of a raw warm front will persist from the Central Plains through the Midwest, including much of the Great Lakes, while severe storms hit the Southern Plains. Strong to severe storms are possible from western Missouri through central Texas. The greater Kansas City area as well as central Texas are the two areas we’re concerned about in terms of the best risk for heavy, severe storms. Not only will the conducive upper-level winds be present, especially toward the Kansas City area, but this is where the greatest instability, or CAPE, will be found. Tornadoes will be possible, so having weather alerts activated on your devices is crucial to staying safe.
On Thursday, the surface low pressure will eject into the Central Plains and eventually the Midwest during the day. Some severe weather is still expected on Thursday, but it will not be as widespread compared to Tuesday and Wednesday, and the components responsible for producing these strong storms become displaced. Instead of the strong jet stream winds overlapping with the strong, low-level jet, the instability, and moisture, it will be to the north, far enough north to prevent widespread severe weather. Nonetheless, strong to severe storms are expected from the Midwest in the Chicagoland area southwestward through the eastern Southern Plains. The best risk for severe storms will be near the surface low in the Midwest. Showers and storms will also extend into the interior Northeast and northern New England.
Then overnight Thursday, the line of the storms will break up, but will continue from the western Ohio River Valley through the Mid-Mississippi River Valley. Spotty storms will remain in place in the eastern Southern Plains. Showers and storms will also continue in the interior Northeast. The best risk for the strong storms will be in the western Ohio Valley.
By Friday, we’ll still be tracking this line of storms as they head into the northeastern US ahead of a cold front, and additional severe storms, containing small hail and damaging winds, in the Ohio River Valley. Storms will streak from northern New England through the Texas Gulf Coast.
As the storms approach the East Coast on Saturday, they will weaken. In terms of rainfall this week, the heaviest will be found in the Midwest where over three inches may fall in some locations. Otherwise, a widespread 0.5 to 1.5 inches if forecast for the Central US.
Stay with WeatherOptics this week for the latest developments on this severe weather outbreak.