Twin States Weather Blog

Quick Afternoon Update

* Please forgive the infrequent updates lately - I've had some major computer issues...

* We need to take some time to discuss the evolution of the severe weather threat for Thursday. The latest computer model guidance suggests that a potent upper trough will form and move through the central U.S. This trough will be accompanied by a deepening surface low, which will move from Arkansas towards the Ohio Valley. Historically, this is a favorable setup for a significant severe weather episode across our part of the world.

* There are several things that are enhancing the severe weather threat. We'll do a PLUS (+) and MINUS (-) breakdown of these factors. A PLUS+ is something that is enhancing the severe weather threat, while a MINUS- denotes a factor that is working against the severe threat. Of course, we are fans of the minuses. Here we go:

+ Approaching negatively tilted shortwave
+ Screaming 65-70 knot low level jet (measured at 850 millibars)
+ Position of surface low and upper trough
+ Low level wind shear

- Upper level winds are unidirectional (from around 700 millibars to 200 millibars)
- Questions about availability of moisture-rich unstable air

* It should be noted that my opinion is that there will be sufficient moisture-rich air to support severe weather. But, our models are not overwhelmingly favorable in this department, so we'll leave it as an uncertain minus.

* We believe the main threat will be damaging winds within a squall line, but a significant threat of tornadoes will exist if supercells can develop ahead of the squall line.

* Timing: The worst of it here will occur between 8:00 am and 8:00 pm Thursday. We will narrow this time frame down later tonight and again tomorrow.

* Location: While the largest threat of tornadoes will come along and west of the MS/AL state line, there is the potential for tornadoes area-wide. And, almost all of us will have to deal with a very powerful squall line.

* Other opinions: Jeff Craven (a very bright severe weather researcher) over at the NWS in Jackson says that this event seems very favorable for a significant episode of severe thunderstorms and possibly tornadoes. He believes the worst threat will be along a corridor from Natchez to Laurel and possibly Meridian. We agree with most of these ideas.

* Bottom line: This is a good time for you, your family, your workplace, and your school to review their severe weather safety plan. Check the batteries in your weather radios and make sure they are working properly. If you don't have a weather radio, now is a good time to make a small investment that could save your life. They are available at any local consumer electronics store.

posted by WTOK Weather Staff @ 4:03 PM