Severe WX April 28th-29th, 2020 Severe Weather Threat

[Taylor Campbell]

A thread for the severe weather threat tomorrow April 28th and Wednesday April 29th, 2020.

 

[Brice]

Isolated tornadoes possible

 

[Bevo]

The volatile environment ahead of the squall line makes me nervous...none of the models are showing development occurring directly ahead of the line (save for the most northeastern parts in AK/OK) but the environment in and around the Dallas-Fort Worth metroplex seems very conducive to tornadoes should something pop up. I'm talking 600+ SRH and 3500+ CAPE around 04z. Looking at the 2% tor SPC risk at the current moment makes me feel a bit better since they don't seem to have higher confidence in development, but still...

 

[Brice]

The volatile environment ahead of the squall line makes me nervous...none of the models are showing development occurring directly ahead of the line (save for the most northeastern parts in AK/OK) but the environment in and around the Dallas-Fort Worth metroplex seems very conducive to tornadoes should something pop up. I'm talking 600+ SRH and 3500+ CAPE around 04z. Looking at the 2% tor SPC risk at the current moment makes me feel a bit better since they don't seem to have higher confidence in development, but still...

The biggest chance for tornadoes will be, of course, the supercells that form in Texas/Oklahoma and the Midwest with a line of possibly discrete cells. I agree enhanced risk is enough since it will be a couple of squall lines rolling through.

 

[Bevo]

Now there’s something you don’t see every day—wind driven moderate risk.

 

[Bama Ravens]

BMX forecast discussion. They sound unimpressed with the threat for their area.

Wednesday through Monday.

Due to a stronger than expected cold pool from early morning
storms to our west, the severe weather threat for Wednesday
afternoon now appears that it may not materialize in the same
fashion as previously expected. A weakened band of convection
should enter west Alabama around 6 AM with MUCAPE of 500-1000 J/kg
possible in a small corridor ahead of the line. Isolated strong
to marginally severe wind gusts cannot be ruled out as this band
moves across the forecast area through the morning. There is
little evidence pointing toward restrengthening of the line, but
daytime heating could help maintain a chance of marginally severe
gusts across our eastern counties during the afternoon. For
consistency and to avoid wholesale changes, a Marginal Risk will
be kept in our forecast but only for isolated damaging winds.
Additional showers or perhaps a few thunderstorms could develop in
the afternoon and evening as strong PVA and mid-level cold
advection occurs from the northwest. This potential is unclear,
but gusty winds might be possible with any such convection.

 

[Kory]

Yeah this looks like a nasty damaging wind threat to our NW. The QLCS will begin to lose focus as it shifts SE away from better instability and forcing (I.e toward MS/AL/TN).

 

[Bevo]

DFW Metro upgraded to moderate for straight line wind damage 75+mph. Might be looking at a derecho event? What an absolute monster of a system, reaching all the way from Illinois down to south Texas.
Would be a good idea to charge up electronics now before this rolls in, because there could be a good bet that some power grids are gonna be throttled.

 

[MattW]

For Atlanta, the HRRR and NAM 3km paint almost opposite pictures, though I notice the NAM does seem to be trending somewhat downward in terms of threat.

 

[Kory]

For Atlanta, the HRRR and NAM 3km paint almost opposite pictures, though I notice the NAM does seem to be trending somewhat downward in terms of threat.

As it does 99% of the time.

 

[NorthGaWeather]

The SPC outlook covers it well. Even with re-development, the severe threat will be isolated to scattered.

 

[KoD]

And we're off

 

[bwalk]

Tor warning for NE LA. (until 6pm)

 

[Austin Dawg]

The SPC outlook covers it well. Even with re-development, the severe threat will be isolated to scattered.

Good. We don't want none.

 

[Bevo]

Oh man there’s probably some nasty straight line winds with this sucker. ETA Denton probably 30ish mins.

 

[bwalk]

At 11:30 pm a solid wall of connecting Severe Thunderstorm Warnings from sw of Ft. Worth all the way to the Missouri state line. Been awhile since we’ve seen that long of a continuous line of warnings.

 

[Tyler Penland]

Interested to see what happens in GA/sc/nc later on. Every model had an initial round of convection coming through this morning from the leftovers of that Midwest line that decided to visit the LA gulf coast instead. HRRR has pockets of decent instability developing. Still won't be widespread severe by any means but could keep things more interesting.

Sent from my SM-G960U using Tapatalk

 

[Weatherphreak]

Wonder how this huge mass of rain on the gulf coast affects development in north/central Alabama.

 

[CSimonds]

The SPC completely dropped NE AL out of the slight risk about 25 minutes ago. They shaved it way back to just SE AL now.

 

[MattW]

And now the slight risk is entirely gone.