Severe WX Wednesday/Thursday/Friday April 17th-19th Severe Threat

[amp1998]

SPC just did a day 3 upgrade to enhanced with hatched sig threat for LA/MS.

That's rare that they do that.

 

[Kory]

That's rare that they do that.

Last time they did that for that area was 2/23/16 outbreak.

 

[CheeselandSkies]

That's rare that they do that.

Wow. That's just about unheard of. I was just looking over the NAM and 3k NAM and thinking LA might get the big long track tornado on Thursday that they didn't on Saturday.

 

[Kory]

Wow. That's just about unheard of. I was just looking over the NAM and 3k NAM and thinking LA might get the big long track tornado on Thursday that they didn't on Saturday.

It's difficult for Louisiana to get those. With the close proximity to the Gulf, too much forcing blows up into a mess. I think W/WNW flow events work well for them. See 2/7/2017 with the Akers and New Orleans tornado.

 

[CheeselandSkies]

It's difficult for Louisiana to get those. With the close proximity to the Gulf, too much forcing blows up into a mess. I think W/WNW flow events work well for them. See 2/7/2017 with the Akers and New Orleans tornado.

Yeah, that's why high risking them is silly which SPC seems to have finally caught on to.

 

[Kory]

If we get instability values to come in a touch higher on the Euro, it would mean big problems with shear values like such.

 

[warneagle]

I agree with the day 3 enhanced upgrade. That area looked particularly volatile on the NAM without the VBV issues that look likely further west on Wednesday and with shear vectors that favor a more cellular mode. The 3km NAM pops some PDS TOR hazard types down there unsurprisingly.

 

[Richardjacks]

looking at the 3k NAM, it has the highest td's in central Alabama, topping out around 66°n 69° in west Alabama, if that is correct, there will be trouble. I have seen this model overplay this before, but typically during the winter. We are well into April and with the warm temps, it isn't going to be as difficult to get the higher theta e air further north...especially if there is any kind of delay of just a couple of hours.

If there is a surface low around HWY 278, that may actually cause the Td's be lower as surface winds will be more easterly....looks like there is a fine line for all of this to come together in Alabama, but if it did, it would be trouble.

 

[Richardjacks]

Also, there are considerable timing differences in when exactly the south and north troughs phase...on the GFS it happens earlier, that would allow more time for the higher td's to move northward, also allow cold temps aloft to come in before the squall line. Will be interesting to see if the GFS folds to the NAM or the opposite happens. These two gifs are for the same time period

 

[Kory]

The NAM has a tendency to be slow.

 

[Gail]

I'm waving the white flag for Mississippi. We've had enough fun with severe weather for this season! Bring me the sunny, 90+ days of summer with occasional afternoon showers/storms.

 

[Richardjacks]

 

[gangstonc]

Is that our secondary low?

 

[Richardjacks]

Is that our secondary low?

Yes, instability is still in question

 

[gangstonc]

Yes, instability is still in question

Are the models or converging yet? It looks like lower level temps will be there. Is moisture return a problem, or will the mid and upper levels be warm and saturated?

 

[MattW]

Does anyone see this being a problem for Georgia on Friday morning? I'm not seeing that there's good conditions for severe weather, just strongish thunderstorms, but I'm also not nearly as experienced as others here.

 

[mattdanielwx]

Does anyone see this being a problem for Georgia on Friday morning? I'm not seeing that there's good conditions for severe weather, just strongish thunderstorms, but I'm also not nearly as experienced as others here.

I see it as a problem for areas south of I-20.....so for South/Central GA. Could see a line with a damaging wind and isolated tornado threat Friday AM

 

[Richardjacks]

I am a bit surprised to see this

 

[kcyalater]

What is the SPC seeing that we aren't?

 

[Kory]

Mesoscale models working in about 1000-1200 J/KG CAPE ahead of the main QLCS. That amount was very sufficient for last weekend and I suspect the same here.