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

[Kory]

The worst of the QLCS runs north of the ENH risk. Some nasty streaks in that thing later today from MS into AL.

 

[Kory]

There’s a tongue of instability on the mesoscale models that makes it all the way to the MS/AL/TN junction. If that’s correct, things will be surface based pretty far north enhancing the severe threat.

 

[CheeselandSkies]

Yeah, if the HRRR and 3KM NAM are anywhere close to correct, much of MS into western AL is going to have big problems today. Time to go watch the Weather Xtreme video!

 

[South AL Wx]

Looks like the Enhanced Risk was expanded slightly to the north on the latest SPC outlook.

 

[Richardjacks]

Looks to me that there is a warm front forming near Tuscaloosa, got to watch for any cells in that area...may also act a triple point as the MCS moves east with damaging wind threat.

 

[Kory]

Looks like the Enhanced Risk was expanded slightly to the north on the latest SPC outlook.

This is a friggin joke. C'mon SPC

 

[Bama Ravens]

 

[darkskys25]

Qlcs looks a little stronger a little further north on the hrrr this morning so I guess that is why they pulled the enhanced slightly north. The cells in south al will have the best chance of producing tornadoes today imo. Hrr has been consistent on that.

 

[NorthGaWeather]

This is a friggin joke. C'mon SPC

I think Mr. Edwards has a good handle on the 13z outlook. A nudge to the North is appropriate, as the 6z outlook was too conservative.

 

[Kory]

I think Mr. Edwards has a good handle on the 13z outlook. A nudge to the North is appropriate, as the 6z outlook was too conservative.

That’s what I was referring to. We have knee jerk responses to a couple CAM runs and the outlook trimmed back and then immediately updated nearly to original extent north.

We can’t even get consistency from one agency over the course of one day much less across several government agencies.

 

[apocalyptic_pleasures]

Sounds like they may be dropping the significant tornado threat. Sigtor values drop fast as it moves across south Alabama similar to how they did Sunday although that still produced the one in Troy.

A modulating influence, however, may be storm mode. The bulk of
convection should be quasi-linear, with only conditional potential
of warm-sector supercells surviving long enough to become tornadic
in that favorable environment before being overtaken by the MCS.
QLCS tornadoes (which occasionally can become significant also,
though not to the frequency and duration of supercellular ones) also
are possible as the convective band impinges on the high-SRH and
marginally to moderately unstable boundary layer. For now, will
maintain the significant-tornado area with some peripheral
modifications.

 

[NorthGaWeather]

That’s what I was referring to. We have knee jerk responses to a couple CAM runs and the outlook trimmed back and then immediately updated nearly to original extent north.

We can’t even get consistency from one agency over the course of one day much less across several government agencies.

Oh, now I agree with that. The people placing their hopes and dreams on a particular model run are ridiculous. Every model is wrong. Some are just less wrong than others. One should never make a forecast based on them alone. This is where skill comes into play. But this is another topic for another day.

 

[bjdeming]

sure suggests a bow echo/derecho pointing right at B'ham.

Something I was wondering about Sunday night: can you get tornadoes and a derecho at the same time? That's sure what it looked like in the Northeast then, but I haven't had time to look into the theory.

 

[Timhsv]

The worst of the QLCS runs north of the ENH risk. Some nasty streaks in that thing later today from MS into AL.

I saw that in the MAX UH, so Im wondering whats with SPC thinking's?

 

[Taylor Campbell]

Purely off of all the things to forecast with I should be under an enhanced risk by the SPC, and local NWS, but I’m not. That doesn’t mean I won’t treat it like it.

 

[bjdeming]

As for today, and perhaps this, from the current day 1 outlook, answers the tornado/derecho question, too (emphasis added):

A modulating influence, however, may be storm mode. The bulk of
convection should be quasi-linear, with only conditional potential
of warm-sector supercells surviving long enough to become tornadic
in that favorable environment before being overtaken by the MCS.
QLCS tornadoes (which occasionally can become significant also,
though not to the frequency and duration of supercellular ones) also
are possible as the convective band impinges on the high-SRH and
marginally to moderately unstable boundary layer.

The biggest problem getting a lay understanding of weather is that it is so incredibly complicated, beyond the capabilities of any explanatory model for general public use (i.e., to me). I get the tornado general model. I get the derecho general model. Put them together and up in the sky coming at people, though, and it's often boggle time.

 

[TornadoFan]

Storm Prediction Center Mesoscale Discussion 387

Severe weather, tornado, thunderstorm, fire weather, storm report, tornado watch, severe thunderstorm watch, mesoscale discussion, convective outlook products from the Storm Prediction Center.

www.spc.noaa.gov

 

[Weatherphreak]

It’ll be interesting to see how far the warm front and low make it in relation to the line moving through North Alabama. GFS, FV3, and Nam3k appears to have the low around Nashville as the line is passing through which would lead me to believe that the threat could extend all the way to the state line. The HRRR looks to have the low around Muscle shoals which goes along with the enhanced look. At this point it’s a wait and see. I’ll be at the Havoc game when all those blows through so hopefully it’s not too serious.

 

[Kory]

74/64 in Tuscaloosa with sun.

 

[Richardjacks]

74/64 in Tuscaloosa with sun.

I dont remember any model showing tcl td that high this early