INSIDER BLOG: Tracking and timing strong storm potential for Saturday

SETUP:

For the majority of the past week, we've had something called a "Rex Block" positioned over the eastern half of the country. This is essentially a big area of high pressure in the upper levels of the atmosphere that sits north of an area of lower pressure. This has blocked any form of active weather for us this week, leaving us sunny and warm. That is already changing as that upper level ridge of high pressure is starting to break down and shift east.

This is allowing a trough of low pressure aloft to move in from the west. This will develop an area of low pressure at the surface that will ultimately drive storms into central/eastern Kansas by Friday.

Storms will run out of steam Friday night as instability wanes overnight. Just a day ago, it looked like this would save us here in mid-Missouri, but as new data rolls in this morning, it appears that may not be the case. From the beginning, we've been talking about timing. This system certainly will live or die for us in central Missouri on timing. The progression of the low looks to be slowing in latest runs, meaning the passage of the cold front is looking like it may take longer to clear the region. What I'm getting at, is that some of us will reach the hot and steamy mid-afternoon hours before the cold front reaches us. If that's the case, those areas (largely east of HWY 63) will have a chance at an isolated severe storm.

IMPACTS:

If we manage to get storms to develop, the most likely impacts will be damaging wind and large hail. Plenty of instability will develop along the front, and enough shear will accompany the front, that we could develop an organized line of storms.

WHAT COULD CHANGE:

The biggest variable here is clearly timing. If recent trends are wrong, and this system speeds out of mid-Missouri by the noon hour, then we may not see any severe threat in the region, in which case St. Louis would be at greater risk. If we see current trends hold or progress, the severe threat will remain or possibly shift closer to our neck of the woods.

TIMING:

The most likely time frame for severe weather will be between late afternoon and early evening.

WHAT TO KNOW:

In either scenario, this is NOT the type of severe threat we saw at the end of March and beginning of April. As it sits right now, we expect a line of thunderstorms that will pose an isolated severe risk within it. Pay attention to the forecast leading into Saturday for final details on timing of storms, and for any last minute changes in the forecast.

As always, be sure you know how you'll be alerted of severe weather, and know your plan ahead of time. Download the ABC17Stormtrack Weather App for on the go alerts, and we always recommend a NOAA Weather Radio for a backup at home.