Severe storms 3-9/12

[AfewUniversesBelowNormal]

Nice setup on the Euro

 

[Chinook]

GFS is showing some higher EHI and other parameters in eastern Texas and Louisiana, 18z Saturday to 00z Sunday. If you check the Euro forecast reflectivity maps, it shows some heavy storms in Arkansas in this time period. Both models have <995mb in Kansas on Saturday. So these models are not too different, considering 120 hrs in the future.

[raindancewx]

CIPS has an interesting analog list for the outbreak. 

DATE	300HGHT	500HGHT	850HGHT	850SPED	PMSL	THICK	850TMP	2mTMP	PWTR	925MIXR	2mDWP	F120	F132	F144	FINAL
20120123/0000	0.842	0.798	0.751	0.880	0.755	0.780	0.729	0.853	0.932	0.936	0.855	11.074	12.279	11.514	11.622
19840218/1800	0.912	0.918	0.807	0.859	0.787	0.718	0.626	0.807	0.933	0.873	0.887	10.362	12.240	12.101	11.568
20010225/0000	0.740	0.788	0.860	0.888	0.841	0.876	0.756	0.850	0.942	0.914	0.893	12.276	12.738	9.237	11.417
19920218/0000	0.863	0.874	0.793	0.884	0.796	0.689	0.733	0.840	0.892	0.929	0.912	8.962	12.456	12.326	11.248
19920215/0000	0.769	0.745	0.810	0.900	0.695	0.616	0.506	0.759	0.861	0.784	0.627	11.960	10.979	10.524	11.154
20070301/0600	0.800	0.782	0.770	0.841	0.647	0.826	0.609	0.825	0.855	0.736	0.733	10.684	11.312	11.203	11.066
19820403/0000	0.764	0.778	0.690	0.851	0.755	0.680	0.788	0.663	0.889	0.867	0.826	10.639	11.585	10.907	11.044
20130210/1800	0.719	0.708	0.785	0.860	0.798	0.702	0.614	0.742	0.895	0.932	0.818	12.112	11.690	9.194	10.999
20070225/0000	0.866	0.831	0.689	0.874	0.773	0.739	0.720	0.875	0.906	0.873	0.761	9.104	11.880	12.004	10.996
20090405/0000	0.851	0.847	0.618	0.794	0.615	0.516	0.731	0.787	0.864	0.828	0.847	11.598	11.093	10.293	10.995
19860318/1800	0.543	0.612	0.791	0.836	0.788	0.758	0.538	0.683	0.917	0.880	0.811	10.248	11.155	11.549	10.984
20060129/0000	0.713	0.707	0.790	0.837	0.852	0.693	0.799	0.820	0.930	0.868	0.838	10.544	12.094	10.243	10.960
20020219/1800	0.710	0.716	0.708	0.763	0.717	0.806	0.592	0.702	0.849	0.832	0.815	11.357	11.050	10.254	10.887
20080411/0000	0.835	0.895	0.898	0.872	0.895	0.679	0.838	0.788	0.935	0.889	0.802	8.264	12.851	11.290	10.802
19820122/1800	0.636	0.675	0.708	0.863	0.773	0.863	0.632	0.823	0.810	0.698	0.526	11.846	10.754	9.800	10.800

[Sydney Claridge]

GFS and the GFS-FV3 seems to bring a front with storms through the DFW area early-to-mid morning, whereas the Euro seems to be slowing that front down a bit (bringing it through DFW around noon).  For my location, it would be interesting to see if the other models trend to slowing down the front as the event draws closer.  Still a few days out so we'll have to see, but currently it sounds like this would be more of a concern for east Texas than for DFW.

EDIT: though not for this timeframe, it is also interesting to see the GFS and Euro show another storm system next Tuesday as well.  I'm wondering if we are about to move into a pattern that is much more conducive for severe thunderstorms (and not just because of the change in seasons).

[1900hurricane]

The SPC has thrown up a large Day 5 15% risk area for Saturday, March 9th.

Quote

Day 5, a surface cold front is progged to sweep across the central
   and southern Plains and into Missouri/Arkansas through the day, and
   then quickly eastward across the Mississippi River into the Ohio and
   Tennessee Valleys overnight.  While the strongest large-scale ascent
   is progged at this time to sweep across the Ozarks vicinity during
   the day, as the trough takes on a negative tilt, substantial
   questions remain as to the degree of moistening/destabilization that
   will be able to occur this far north.  Greater severe risk may
   therefore remain farther south, from east Texas/Louisiana across the
   Lower Mississippi Valley region, and possibly into the central Gulf
   Coast states late.

   Aside from questions regarding instability, this appears likely to
   be a strongly dynamic system with strong flow/shear covering a broad
   area.  As such, damaging winds, and potential for tornadoes, is
   evident at this time.  At this time, a large 15% probability area
   will be issued centered on a north-south zone from Missouri to the
   Lower Mississippi Valley, with additional areal, and risk-level,
   refinements to be made in subsequent outlooks.

 

[Tallis Rockwell]

Instability is going to make or break this event. Lift and  shear is forecast to be more then favorable. I think GFS is underestimating the CAPE.

[AfewUniversesBelowNormal]

Euro last night is no longer a closed low, but it does have the NE trough that you see in outbreaks. 

12z GFS is 990mb

[AfewUniversesBelowNormal]

18z GFS doesn't look bad. It's early in the year though. 

 

[CheeselandSkies]

Another one of those times I'd like to bottle and save this pattern for May. Watch these systems be moisture-starved and then we're stuck in a blocky eastern trough pattern for the balance of May.

[andyhb]

Wrong system @AfewUniversesBelowNormal

The SPC outlook is for 3/9, which is the shortwave before the one you keep posting maps for.

[raindancewx]

Generally when we get snow here (Albuquerque) in Spring down to the valley floor in Mar-May - keep in mind our highs are 57F (3/1) to 85F (5/31) in Spring - I find the Plains or South do tend to get pretty nasty outbreaks. We had about an inch of snow in town on 4/29/2017 for instance (during the day no less, amazing cold with that system). The European system shown on 3/12 is probably powerful enough to bring snow down to the valleys almost to El Paso if it verified as shown.

[1900hurricane]

To be fair, the days the thread specifies March 10th and 11th. As it now stands, it appears the main days for the two systems will fall on March 9th for the first one and March 12th for the second, meaning both systems actually fall outside the scope of the thread.

[AfewUniversesBelowNormal]

00z Euro.. it may now be trending toward a wind/squall line threat vs primarily tornado outbreak. Time to trend of course, it's taking on the El Nino seasonal characteristic. 

[bjc3395]

I disagree. This is looking increasingly like a long-duration supercell event across the states of Louisiana, Arkansas, Mississippi, Alabama, and Tennessee. Very well put together system we are dealing with here, with rapid destabilization ahead of the front likely. Storms will be able to keep pace, too. 

 

These are some of the largest non-contaminated hodographs I’ve seen for quite some time. I’ll also note the instability progged by all models is looking like an underforecast, at least for southern areas. 

[Sydney Claridge]

1 hour ago, AfewUniversesBelowNormal said:

00z Euro.. it may now be trending toward a wind/squall line threat vs primarily tornado outbreak. Time to trend of course, it's taking on the El Nino seasonal characteristic. 

That's for the 3/12 system based on the timestamps that I see.  I had thought that one had looked a bit more like a squall line based on the GFS models I had been looking at anyways.  What do you think of the 3/9 system?

[AfewUniversesBelowNormal]

3 hours ago, BrandonC_TX said:

That's for the 3/12 system based on the timestamps that I see.  I had thought that one had looked a bit more like a squall line based on the GFS models I had been looking at anyways.  What do you think of the 3/9 system?

It seems the first one stole a lot of the potential energy, both are real threats. I'll make the threat title March 9-12. 12z Euro looks good. 

Edit: look at this trend on the 12z Euro now of the SW trough. 

[Indystorm]

Despite the intense cyclone out in La La Land the GFS depicts for the east coast at the end of its run both GFS and  FV3 show a rather intense storm cutting up the Plains mid week this coming week in the 18z run.  Will be something to watch for sure.

[raindancewx]

The Euro has been showing pretty huge moisture for the storm on 3/12. These figures are consistent with a pretty powerful storm, and they'd certainly end our 2008-2018 streak of dry Marches. In fact, I think this is the most precipitation I've ever seen depicted for a March storm in New Mexico - 90% of it is for Monday morning to Tuesday evening. I'd have to look, but you have to think if Eastern NM is getting that much rain/snow, there is substantial Gulf moisture coming up.

[CryHavoc]

Day 3 still slight risk.

Somewhat surprised given the moisture content and returns on the hodographs.  I guess Day3 MDTs are pretty rare, but this seems to be a good synoptic setup.

Am betting on a Day2 MDT.  Anyone think this could go HGH day of?

[CheeselandSkies]

Day 3 still slight risk.

Somewhat surprised given the moisture content and returns on the hodographs.  I guess Day3 MDTs are pretty rare, but this seems to be a good synoptic setup.

Am betting on a Day2 MDT.  Anyone think this could go HGH day of?

Doubt it because it's a relatively small area with high CAPE, and there are some VBV issues apparent in soundings. Still verbatim the potential for an isolated nasty event like last Sunday's EF4 is apparent should a storm find a sweet spot.

Sent from my SM-G955U using Tapatalk

[1900hurricane]

Forgive me for looking out a little bit, but verbatim, next Tuesday on the 12Z GFS is probably a few degrees at the surface short of a tornado outbreak for somewhere within the northeastern quarter of Texas. The only thing a little lackluster is the instability, particularly in the low levels. This is the first time the GFS has shown something this volatile so it could just as easily disappear again, but the ECMWF had on and off been showing similar wind fields with the system. It certainly caught my eye, to say the least.

 

[CryHavoc]

1 hour ago, CheeselandSkies said:

Doubt it because it's a relatively small area with high CAPE, and there are some VBV issues apparent in soundings. Still verbatim the potential for an isolated nasty event like last Sunday's EF4 is apparent should a storm find a sweet spot.

Sent from my SM-G955U using Tapatalk
 

Thanks.  Could you link/attach some of the new soundings?  I haven't seen the veer back, but I haven't really had the time to take a look at them.

[AfewUniversesBelowNormal]

This is one heck of a setup. It would be better if it were April or May. (The negative anomaly in the NE going into the Great Lakes is showing up for the first time.)

[Chargers09]

21 minutes ago, 1900hurricane said:

Forgive me for looking out a little bit, but verbatim, next Tuesday on the 12Z GFS is probably a few degrees at the surface short of a tornado outbreak for somewhere within the northeastern quarter of Texas. The only thing a little lackluster is the instability, particularly in the low levels. This is the first time the GFS has shown something this volatile so it could just as easily disappear again, but the ECMWF had on and off been showing similar wind fields with the system. It certainly caught my eye, to say the least.

 

Was just about to post this sounding from KSAT (San Antonio)

[CheeselandSkies]

32 minutes ago, CryHavoc said:

Thanks.  Could you link/attach some of the new soundings?  I haven't seen the veer back, but I haven't really had the time to take a look at them.

Here's one from the 12Z NAM valid for 21Z Saturday from the zone of greatest progged 0-1KM EHI along the MS river/AR-TN border region. Looking at the wind barbs the veer-back isn't as pronounced as earlier runs, but there's a very slight amount of backing from 850 up to 700mb, but moreover the winds look pretty unidirectional albeit very strong at all levels. Even so, there are ample amounts of SRH and EHI depicted.

The wind profile is depicted as much more classic (southerly surface winds, veering to SW at 850mb and WSW at 500mb) farther east near the MS/AL border, but instability is progged much weaker there.

[AfewUniversesBelowNormal]

Big difference between the GFS and Euro right now.. especially with regards to timing. 

[CheeselandSkies]

3 minutes ago, AfewUniversesBelowNormal said:

Big difference between the GFS and Euro right now.. especially with regards to timing. 

For Saturday, or mid-next week?

[1900hurricane]

The discussion of two different events in one thread is a little confusing. Maybe we should split them?

[AfewUniversesBelowNormal]

Euro is 983mb though. 

[1900hurricane]

As of today's 12Z model cycle, the GFS and ECMWF are actually pretty similar for next week's storm system. The ECMWF is a tad slower and deeper with the trough wrt the GFS, but that's a fairly normal bias between the two. I bet the SPC gives Tuesday a risk area in the next 4-8 day outlook.

https://twitter.com/1900hurricane/status/1103749722609717248