Storms Still Expected Thursday – Later Arrival
We have been monitoring the potential for severe storms since last week, as the timing and strength of the storm system out west becomes more clear. In the meantime, it has really felt like spring over the last couple days, thanks to unseasonably warm temperatures, increasing humidity and of course the overwhelming high pollen levels. Today will be no different, with highs again around 80 degrees and a stout southerly breeze between 10-20 mph. Due to increasing humidity and warmer temperatures, clouds have been on the increase, along with even the potential for a sprinkle or two today, but we are expecting the majority to just remain dry under a partly to mostly cloudy sky. Another dry day is expected Wednesday, with highs mostly in the low 80s and a mix of sun and clouds.
As we look ahead to Thursday, model guidance has been trending later with the arrival of showers and storms associated with an approaching cold front. A strong to severe line of storms will be approaching the Mississippi River late Wednesday and will slowly track east overnight, entering northwest Alabama sometime around daybreak to mid-late morning on Thursday.
With dew points surging into the mid (maybe even upper 60s), ahead of the line of showers and storms early Thursday, there will be substantial moisture to support severe storms. CAPE and shear values remain low, but keeping the tornado threat on the low side. With that said, there will still be the potential for storms to rotate and if rotation looks strong enough on radar, a tornado warning or two may be issued, whether or not the storm produces a tornado. So keep in mind you need to have a way to get the latest weather information in case a warning is issued. We learned on March 18th, that it doesn’t take a tornado to cause significant damage, straight-line winds can cause just as much damage as an EF0 – EF1 tornado.
The good news is because instability parameters are not overwhelmingly high, we are not expecting a widespread significant severe weather event, though it only takes damaging straight-line winds or a tornado in your community to make it significant for you. Below the Storm Prediction Center in Norman, Oklahoma has outlined most of the Tennessee Valley and the entire state of Alabama in a Slight Risk area for severe storms Thursday.
This graphic shows where the greatest risk for severe storms will likely be, which is the 30% area outline in red in northeast, east/central and southern Alabama.
As previously mentioned, we are expecting a squall line (line of storms), or QLCS (Quasi-Linear Convective System) as Chief Meteorologist Jason Simpson described in his post yesterday (This Week’s Stormy Weather), to move into northwest Alabama sometime Thursday morning and track east throughout the day. If a QLCS does develop, that will mean a greater potential for individual line segments to bow out and cause severe straight-line winds, or for rotation and possible tornadoes. As the line progresses east through the day Thursday, the environment any storms move into will be more unstable and more conducive for strong to severe storms. This will be the case especially east of I-65 with the line expected to move through during the afternoon hours, as CAPE values are forecast to approach 750 J/kg. That being said, the entire Tennessee Valley has the potential for strong to severe storms Thursday.
Below is an approximate timeline for storms that is subject to change, but is our latest thinking on when storms will be moving through specific areas of the Tennessee Valley. Showers will be possible in northwest Alabama before daybreak Thursday, but storms aren’t expected to arrive until 7:00 am or later.
Northwest Alabama (The Shoals): 7:00 am – 11:00 am
I-65 Corridor/Huntsville: 11:00 am – 2:00 pm
Northeast Alabama: 2:00 pm – 6:00 pm
Today and tomorrow is the perfect time to review your severe weather safety plan with your family and make sure your NOAA weather radio is working properly and has fresh batteries if needed. If you need help programing your weather radio, click here –> ‘How To Program Your Weather Radio‘, for an instructional video by meteorologist Brandon Chambers.
Also there are many ways for you to stay alert of severe weather on your smart phone or mobile device by downloading any of the FREE apps from WHNT and other ways to track storms and receive warnings.
Check back here for continuous updates as the storm system approaches and especially when it moves through Thursday.
- Jennifer Watson
Facebook: Jennifer Watson WHNT