New Year's Eve 2010 Tornado Outbreak: how did the SPC bust so badly?

[harlequin]

I've thought for a while now that last year's New Year's Eve outbreak is pretty underrated. Not here necessarily, as TN avoided any significant severe weather, but just in general.

It killed 9 people and all fatalities occurred outside of the SPC's initial Day 1 Convective Outlook (included below). Even in subsequent outlooks (after a killer tornado had already killed 4 west of Fayetteville, AR) the Slight Risk was only gradually expanded and probabilities never really matched the magnitude of the events (even in MS where several EF2/EF3 tornadoes occurred).

I only point this out because it's one of the most shocking SPC busts I've seen. I wonder if they did an internal assessment of their performance?


Even the previous evening they busted a bit too, although to a much lesser degree.

[Eric]

Without digging into the synoptics and mesoscale features of the system, it's really hard to speculate what really transpired...but I seem to want to remember something about the low-level jet being more intense than progged.  I could be wrong, though...and I've also slept since then.   

[toastido]

Here's a good overview page:

http://www.spc.noaa.gov/exper/archive/events/101231/index.html

Both the 1300 (7am) and the 1630 (1030am) SWODY1 had the assumed "missed' areas covered by a SLGT outline.  Based on the time of the storm reports, they did not bust; the areas were outlined during that time period.

EDIT: I forgot to mention, there were tor watches out in the areas, too. 

[harlequin]

Yeah, I'm aware about the tornado watches and the gradual expansion of the outlooks.

The SPC, though, did bust on some of them. The NW AR tornado that killed 4 was never included in an outlook. Plus the SPC uses the 6z for verification, I think?

Plus for such a significant outbreak the probabilities were quite low. Never going above 5% in any area. Say what you will be I personally think the SPC busted this one.

That isn't to say the general public didn't have warning. They don't pay an exorbitant amount of attention to outlooks and the watches and warnings were certainly adequate.

[Kevin]

The SPC was a bit slow on that part of the event...but nothing really suggested what happened would happen...so hard to say they should have caught it beforehand. I remember waking up being really surprised at what had taken place...but figured once it did it would carry upstream along the LP through MO...which it did. SPC did catch onto that.

I think some of the dynamics ended up stronger than expected...and I wouldn't be surprised if something like terrain effects in NW AR further enhanced the situation. As said...warnings were out in time...so that was most important...but add in the fact it was a pre-dawn tornado during a holiday period in a forested/elevated part of the state...just made for a deadly event.

It may have been a technical SPC bust (not sure of their exact verification standards) but I've seen worse...both events worse than expected and much less than expected. I think the fact it occurred on NYE made it a bit overshadowed...and especially when you think about the events that would follow in 2011...even beyond severe weather but just the major pattern shift that followed days later with the cold/snow.

[tennessee storm09]

i remember the system modeled about a week out... it really looked mean and very dangerous... course the instability wasnt very impressive and the shear was off the charts and a nice lower level jet to work with... meg jumped on it 5 days out, saying all modes of severe possible with tornadoes even... that was one of the earliest systems i ever seen meg say the tornado word that far off.

[bugalou]

and I wouldn't be surprised if something like terrain effects in NW AR further enhanced the situation.

Those sneaky Ozarks always seems to play a quiet role in winter time events.

[@NashSevereWx]

I recall SPC extending a Tornado Watch for N MS into Memphis, only there was some technical/software problem on SPC's end preventing this extension to be communicated to media (The Weather Channel, in particular) and other weather providers (Allison House).  Caused confusion considering the watch extension appeared on SPC's site, and no where else.