Severe Weather Sunday, Continued Threat Later This Week

Sunday, March 26th 2017, 6:08 pm
By: News On 6

Severe weather season in Oklahoma is underway and a risk for large hail, damaging winds and a few tornadoes is with us this evening. A compact low-pressure system is kicking out of the Rockies and bringing a small, but a potent area of forcing for thunderstorms from central into eastern Oklahoma. 

Like many early season events, the lack of instability and moisture is going to downsize the threat somewhat. However, there are other factors that make tonight’s risk the highest Green Country has seen so far this year.

Here’s the break-down. We have got three opportunities for storms from mid-afternoon Sunday until about sunrise Monday. The first wave of storms will continue to push into Green Country with a threat for small hail and nothing more. This round will be the least concerning but could impact areas south and west of Tulsa before 6 p.m.

The second round will form late in the afternoon near I-35 in central Oklahoma (just ahead of the dry line) and push east into our viewing area after 7 p.m. This will bring the primary severe threat tonight between then and midnight. 

The strong wind shear will allow supercells to form, creating the risk for large hail with very cold air aloft in place.  High winds are also likely in the stronger cells. These supercells, by their very nature, will be rotating and bring a tornado risk, especially south of I-40 where dew points greater than 55° are found (a needed component for most tornadoes). 

Storms will eventually outrun the better instability and moisture found in central Oklahoma, but the low-level jet stream (strong southerly winds just above the surface) will allow them to continue to carry eastward to the Arkansas border by midnight. The Tulsa area could see the storms any time between 7 p.m. & 10 p.m. from this round. Below is the HRRR computer model depiction of the radar at 7 p.m.

The final round comes after 10 p.m. tonight, mainly north of Tulsa near the Oklahoma/Kansas line due to the strengthening low-level jet stream. The “nose” of this wind maximum will be the focus for these storms that will mainly bring a large hail threat and perhaps some localized flooding as storms may train over the same locations through the overnight time frame. These should weaken in the pre-dawn hours with the rain exiting our viewing area to the northeast by around sunrise. Fortunately, these storms will not be rooted in the surface and should not bring a tornado risk.

In summary, the greatest threats for the largest hail, tornadoes and damaging winds will be mainly west and south of Tulsa due to the greater fuel available for storms, but the threat will extend into our area with a potentially higher risk along the warm front that will bisect the area from northwest to southeast this evening where greater turning of winds occurs.

Beyond this severe weather event lies another one just a few days later. Another powerful upper level low in this conveyor belt pushes into the southern Plains midweek drawing northward better quality moisture. Its track may be a bit further south, which might keep the threat more contained to our southern areas. 

It’s too early to denote if tornadoes will be widespread or if this will be mainly a hail and high wind event. However, if we can get enough instability into our area, it could be just as big of deal or greater than our more immediate storm system. As the season grows later, the missing components of instability and moisture become more plentiful and the risk will continue to grow. 

The pattern appears to be sitting in place for at least another week or two, bringing a few more rounds of this into early April. This is certainly good news concerning our drought with several inches of rain in the forecast for the next week as shown below.

Now is the time to be prepared for dangerous storms. If tonight’s activity misses your location, be on guard for our next round later this week. I’ll have more severe weather updates on Twitter: @GroganontheGO and on my Facebook page.