2021-04-24 EVENT: AL/FL/GA/SC

[Matthew Wann]

I hope I'm doing this correctly, this is my first time posting one of these, but far from my first time with severe weather. SPC has a 15% risk across the southern area of this region. The NAM, and now NAM 3km (at the end of its range) is showing very high SigTor values across southern Alabama and Georgia throughout Saturday. Attached is a NAM3km sounding from 20 miles NNW of Tuskegee, AL. I believe there is still some uncertainty with moisture return however.

 

[Jeff House]

That's a good first Target Area post. I'm also surprised the NAM has healthy EHI values; I use those more than other blended indices.

I thought the low levels look too veered off eyeballing constant pressure and/or sounding forecasts. Apparently the SRH forecast is enough. Also concerned morning MCS stabilizes things. However, in late April the atmo can recover. CAPE forecast is bullish.

For North Georgia of course the obligatory southern Apps wedge front will be around. Should intersect with the synoptic trough somewhere in the North Georgia mountains. If not the ATL metro. Oh none of that sounds like good chasing, haha!

Meanwhile the NAM is teasing me with what would be low-topped good visibility cells right around Chattanooga. We lack CAPE up here due to the Georgia MCS. If the wedge front lifts this far north, SRH will be quite good despite otherwise veered off low levels. Frankly, I don't believe the NAM for Tenn. However at least I know good spots close to home for viewing things.

In a nutshell I have no storm chasing plans Saturday. We'll see where the data takes us. ARWs in rage next run I believe.

 

[Matthew Wann]

So the past few runs of the HRRR and 3km NAM are consistent, but split. The HRRR seems to want to keep a wedge across North Georgia which would limit northern development, while the NAM is not showing any such thing. Verbatim the HRRR shows 63 degrees for Atlanta at 17:00 EDT while the 3km NAM shows 71 degrees. Both they've both been consistent with themselves on target area, the HRRR wants to center the threat from Montgomery over to Macon while the NAM is centered on Atlanta-Athens. I'm honestly not sure which one to believe, I'm not as up on particular model biases.

 

[Greg Rutland]

I couldn't justify the trip to Tx/Ok today (would have had to drive all night and chase with little to no sleep) but I'm about to leave Florence, Al for the lower Mississippi River delta (and depending on initiation and track I may end up in central to eastern La) to chase lightning photos later today/tonight before circling back to see what develops in central to south Alabama tomorrow afternoon. Will be closely watching model trends.

 

[Jeff House]

Yeah with the system slowing down for Saturday, probably give Dixie and chance if one already lives here. Now it looks like Alabama could get going which has some terrain better than Georgia. However, Talladega National Forest? Please no, just no!

Proper Alabama terrain is north, preferably in the Tennessee River Valley; but, that's going to require some big time destabilization. Currently appears wedge front gets hung up central/southern Alabama, and with it the best juxtaposition of CAPE and shear.

Lead surface trough will be ongoing in southeast Georgia. No thanks. Low level wind will be more backed, but ongoing rain and blobs are not acceptable chase modes.

Back surface trough may work out of Alabama and/or intersect the wedge front. Much of that area will suffer veered off surface winds. Best area with decent wind direction looks to me unfortunately dreadful chase terrain South Bama.

They all keep southeast Georgia rain going through midday. NAM destabilizes the back trough area with hailers, assuming veered off. HRRR is way too bullish. ARWs seems reasonable, some potential but messy.

One thing about the back target is that visibility will probably be good after midday clearing. Also the storms may be more sculped than usual Dixie. However I have yet to see anything (including Day 2) that inspires me to chase.

We'll see how the 00Z stuff goes. I'm far more interested in the ARWs than the NAM or HRRR. ARWs been money in the South this year.