Bob's Burgers

Just now, jojo762 said:

00z WRFs are.... aggressive? Yikes.

Yes. Very interesting seeing the NMMB firing clean convection. 

2 minutes ago, Quincy said:

The 00z 3km NAM is either scary af, clueless or both. I cherry picked some soundings with 700-500mb lapse rates over 9 C/km with Tds in the lower 70s. Even area averaged soundings show lapse rates around 8 C/km with a small capping inversion. Important note is that low level lapse rates in this environment are marginal, in some cases <6 C/km.

If the cold bias is correct, you’d have that tiny cap being obliterated. 

Is it overly simplified to say a HRRR/3km NAM blend is one of the scariest scenarios you could fathom? HRRR is messy with widespread convection, while the NAM is just a little bit too cool in the boundary layer, resulting in very little warm sector convective initiation. 

It's like the ceiling got even higher, but the certainty lower.

Clear as mud what happens tomorrow

and that would be why there is nothing

Yep. The parameter space on the NAM3k is through the roof... and nothing.

That is a very strong run of the NAM, guys.

stout NAM is stout.

Based off what the latest HRRR showed, I feel like what we saw last Wednesday is a pretty realistic scenario. 

This hrrr is definitely weaker. 

A high risk looks practical after seeing these 18z runs.

That is a beastly run of the NAM

1 minute ago, DanLarsen34 said:

Some key context on the language used in this outlook. It’s very rare to see the mention of violent tornadoes in a day two outlook. 
 

Kind of crazy in hindsight that 4-27-2011 wasn’t on this list. 

Expanding the moderate and enhanced northeast would make sense. There isn't quite good enough model agreement for a high risk D2 yet due to storm mode. Some of the HREF members last night had some early convection too which can be a bit of a fly in the ointment. That said, a high risk at 6z would make sense if the 0z HREF shows a strong signal.

4 minutes ago, jojo762 said:

00z CAM run down:

HRRR: Plenty of supercells, but also a fair amount of junk in the warm sector.

NSSL-WRF: Numerous discrete supercells traverse the warm sector... Much less junkvection.

WRF-NMMB: Most aggressive with junk in the warm sector. Maybe some tornadic supercells, but looks awfully junky.

WRF-ARW: Much like the WRF-NSSL is fairly aggressive developing numerous discrete supercells across the warm sector.

NAM NEST: Numerous discrete supercells across the warm sector.

 

Pretty substantial agreement in CAM output that a significant threat will evolve on Thursday... Perhaps the biggest question relates to northward progression of the warm sector with both the HRRR and NAM, as well as the globals being substantially further north than most other CAM guidance was.

You gotta wonder what the next few hours of both the ARW and NSSL WRF would look like; both look like they are forming a lot more storms at 0z when the run ends. 

The ARW is a total slugfest/high-end outbreak.

SPC might have to bring the Slight all the way to Dayton Ohio

The warm sector on the NMMB is enormous 

This takes the threat well into TN too, including Nashville ^^^

That's enough simulated HRRR supercells for one day. LOL

16 minutes ago, CheeselandSkies said:

Thursday's gonna be another one of those "respect the polygon" days...
 

 

This is gold

1 minute ago, brianc33710 said:

Spann generally says a #/5 level threat. Moderate doesn't sound scary but a 4/5 level gets the public's attention.

10 minutes ago, JasonOH said:

FWIW the whole SPC thing isn’t even meant for the general public at all. It’s guidance mainly for mets and to a lesser extent, emergency management (controls staffing levels).  It wasn’t designed for general consumption but it’s gone that way over time. The good thing is that lots of TV mets use the 1-5 scale to communicate it.

Should the SPC evolve the convective outlook in response to the public consuming their products? To me it would make sense for the sake of better hazard communications. 

The second high risk will be this Thursday, March 25th.

27 minutes ago, nrgjeff said:

Thursday will be a regional severe wx outbreak. @CheeselandSkies I think SPC was waiting for American guidance to come toward the ECMWF. It was stubbornly slow this time. Regardless of how we got here, we are at hatched ENH Day 3 now.

First thing I noticed with 12Z guidance is that 500/200 mb winds are forecast WSW. Some of the sloppy South days those winds are SSW. From the SW is plenty of turning. From the WSW as forecast offers robust turning with height. No strange 700 mb winds, smooth forecast hodographs. LLJ is still forecast S or SSW, correct for South severe, even on the squirrelly GFS runs. Winds of course strengthen with height too. 

Warm sector looks a little bigger than last week defined by northward extent of the synoptic warm front. That does not necessarily mean intense severe weather farther north. That'll depend on the outflow boundary situated south of the warm front, and influenced by midday rain. Undisturbed warm sector soundings should have a little EML and lots of instability.

Background pattern is there for a severe weather outbreak. Mesoscale details remain up in the air as usual Day 3, including the size of the region impacted.

Broad troughing like we're seeing with this event Thursday usually bodes poorly for the Deep South and TN Valley. The shear profiles are better, less VBV, storms move off the hodograph... etc. The deep, super amplified negative tilt trough is way overrated. 

Drop the term Moderate. Actually, just drop all the wording together and do a numbered scale 1/5, 2/5... etc.