Twin States Weather Blog

Severe Weather Threat?

* It sure looks like we'll need to beef up our wording about the potential for severe weather Friday and into Friday night. The last couple of model runs have brought the surface low and best upper level support a bit farther south. This would indicate an increased chance of severe thunderstorms.

* The NAM (North American Mesoscale) model indicates a rather strong surface low, on the order of 996 millibars. But, the GFS (Global Forecast System) model shows a much weaker surface low, with a minimum pressure of around 1004 millibars. Lower pressure = higher severe weather threat. It should be noted that the GFS has outperformed the NAM over the last few months.

* It's too early to really define the main threat with this system. For now, we'll just go with the broad-brush idea that large hail, damaging winds, and even some isolated tornadoes are possible. The tornado threat will hinge on what type of storms we're dealing with: isolated supercells would have a greater threat of tornadoes than a squall line.

* Timing: The time of maximum concern comes between noon Friday and midnight Friday night. We'll try to narrow that down a bit tomorrow.

* I'll closely review the afternoon and evening model guidance and post an update here later this evening....

posted by WTOK Weather Staff @ 3:02 PM