Historic outbreak Sunday: The aftermath

[WaitingForSiren]

It appears increasingly likely that a major severe weather outbreak will occur starting march 9 and ending march 11. I wasnt too excited about this this morning, but now that Ive looked at the latest model data and HPC data Im in a daze.



As you can see an intense storm is exiting the southern rockies and entering the southern plains with strong cyclogenesis. The storm should move in slowly, ensuring ample moisture return, with plenty of dry air getting wrapped in from the west given the location of the Low and its time of strengthening. I think this could be the single biggest severe weather/tornado outbreak of the entire season. Here's my graphic of where it will all go down:





This is still a long ways out, but I think its close enough to say that it wont be a bust as far as the models tearing it apart or anything. Also, HPC and CPC both agree on it, so that boosts my confidence.[/img]

[conestogo_flood]

What are you saying?! HIGH RISK! Seriously? Anyone comment, I don't follow what is going on.

[WaitingForSiren]

Haha. that was just my preliminary risk graphic. It might need some tweaking, and probably will, but I am confident on an outbreak of tornadoes with this system. And you can ask everyone, wx mann and extremeweatherguy, they will tell you i am usually conservative about severe weather events.

[WaitingForSiren]

Also, this storm should bring beneficial rains to many areas in the plains. Its been very dry in MN recently, so this is a good thing, even IF theres no snow involved.

[SamSagnella]

I get rediculously antsy around this time of year for obvious reasons, the problem is that the chase terrain in that part of the country is crappy at best. On 3/21 of last year my chase partner and I were in eastern OK and we missed a tornado literally because it touched down behind a hill, and since then east of I35 has been less than appealing to us. That being said, however, if this system actually materializes in the fashion currently being indicated by several models, then I am all for giving crap terrain another shot -- that is a pretty damn awesome sight to see this early in the season (996mb surface low in the OK/TX panhandles). yeeha!

[jkt21787]

I'm not ready to get too much into specifics, but I completely agree with you. Barring major changes in the models, a significant if not major severe weather and tornado outbreak would be quite possible if not likely with this system. Pretty good map you have there above, I would not be surprised to see risks (perhaps not as large) to continue north and east of where you indicate as well. It will of course all depend on several features (SLP track, timing, etc) on that.

The system has been consistent for days, not only within models but between them, which certainly gives confidence, even at this range. Still, a lot could change so my best advice is that anyone in the Plains, MS/OH/TN Valleys, and Southeast keep a very close eye on this possible severe weather event.

[conestogo_flood]

This is exciting. Might this affect southern Ontario in anyway?

[wxmann_91]

Yes this has been mentioned in other boards. Very impressive indeed. It's not too often a 990mb low is shown for 5 consecutive days in about the same region on all the major models. That's agreement there.

[WaitingForSiren]

Nice to see people are agreeing with me, I thought you guys would think my forecast was a bit extremist. And yeah i agree that the severe threat might be even further north and east, into the tennessee valley and ohio valley possibly. I just was having too many uncertanties because the GFS takes this storm slowly towards the great lakes and doesnt really have that favorable a pattern for a big time ohio valley event, but I could see a severe event in that area if the models come together better.

[wxmann_91]

Looking at the GFS, the 12Z run (I hate looking at 18Z runs several days out), paints two systems, both sub-990 and strongly negatively tilted. And, last night's 0Z run had a good sampling from the EPAC.

[Weatherfreak14]

I agree on this situation it looks that the severe weather will start on the plains and move into the midwest later on.

[WaitingForSiren]

After looking at todays model data, I think Friday will be the big outbreak date now. The storm is moving in slowly according to the models, but thats not necessarily a bad thing as it will ensure ample gulf moisture by the time the main storm system finally ejects out. My only concern right now is whether or not a strong enough environmental turnover (dry to moist, like in the major outbreaks) can occur. I mean, if a bunch of gulf moisture sits in an area for a long long time, it might not get unstable enough for an outbreak of tornadoes. Also, I think the high risk area i pointed out might have to be lifted northward closer to st louis with a slight risk as far north as southern nebraska and southern iowa. Heck, i could see a moderate risk in southern nebraska and southern iowa if this thing goes as far north as HPC is indicating. I guess we'll have to wait some more.

[WaitingForSiren]

I went ahead and made two new graphics for this whole deal (3-8-3-11), the first is for both wednesday and thursday, and the second is just for Friday. For my logic, if youre wondering, I figured that since a sub 1000 mb low will be centered in the central CONUS on wednesday that gulf air will rapidly move northward, and since theres cool air in place north if this boundary i figure a nice overiding event might set up with severe storms lining up just south of the boundary. This should be mainly across northern missouri into illinois and as far north as michigan on wednesday. Then, on thursday a low will strengthen in western kansas and with that cycogensis I expect more severe storms to fire up on thursday across kansas and oklahoma, thus the mdt risk over those areas.

On friday the main event happens, with the storm finally exiting out of the rockies and entering the plains, about to eject eastward. The strength of the low (980s mb), widespread gulf moisture and strong shear should result in a major severe weather outbreak. This is all very preliminary and quite a ways out yet (5-7 days), but i think its close enough and the models are consistent enough to discuss the severe weather potential and take it seriously.




[/img]

[wxmann_91]

After looking at todays model data, I think Friday will be the big outbreak date now. The storm is moving in slowly according to the models, but thats not necessarily a bad thing as it will ensure ample gulf moisture by the time the main storm system finally ejects out. My only concern right now is whether or not a strong enough environmental turnover (dry to moist, like in the major outbreaks) can occur. I mean, if a bunch of gulf moisture sits in an area for a long long time, it might not get unstable enough for an outbreak of tornadoes. Also, I think the high risk area i pointed out might have to be lifted northward closer to st louis with a slight risk as far north as southern nebraska and southern iowa. Heck, i could see a moderate risk in southern nebraska and southern iowa if this thing goes as far north as HPC is indicating. I guess we'll have to wait some more.

It's a bad thing for me since our orchestra has a performance at a festival a week from today. Figures that an outbreak would occur on the day I am unable to track it.

[WaitingForSiren]

Thats alright man, Ill track it for you. Lol.

[WaitingForSiren]

And on another forum site I saw somebody bring up an interesting question: Do you think the models are underdoing the moisture that will be brought north from the gulf? Well, I definitely do. Graphical forecasts from NWS only show dews in the 40s and low 50s over my MDT risk area for wednesday and thursday, and 40s and 50s over the high risk area for friday. This is ridiculous. I think 60s dew points will nudge up to central missouri by wednesday evening at least.

[Indystorm]

As you well know it is early to specify geographical risk areas a week out, but given what the models show now I think you are pretty much on target as you await further refinement in future model runs. The consistency of this intense system in run after run since last Sunday has been amazing along with the consensus of models that something big is going to happen somewhere next week. Need to keep watching and hoist alerts as we get closer to the event.

[WaitingForSiren]

00z gfs just came in and seems to show Thursday being the big outbreak now. Shows a mid 980s mb low with intense convection over the central plains...Hmm, Im beginning to think it might all just go down on Thursday, but Friday could be another outbreak further east. Im sticking with my graphic for friday right now, but the one for wednesday and thursday may need some tweaking tomorrow.

[Extremeweatherguy]

Looks like you may have to extend a threat level down into SE TX as well. 00z GFS shows a squall line type feature on Thursday moving through SE Texas and with strong upper level winds and lots of gulf moisture this can spell trouble.

[WaitingForSiren]

Yeah, I think Ill extend thursdays threat level into southeast texas to give you guys a slight risk. I could see a lot of hail in SE texas from this along the dryline. Also, latest GFS really blows up fridays storm and heads it almost due north into the dakotas....I think its too far west with the storm, though. I think fridays storm will head more towards des moines or southern MN. either way, friday still looks like a big outbreak along with thursday, back to back outbreaks i suppose.