Chris Hayes
EF5
That is the longest track tornado since November 23, 1992.
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There were well over 1000 tornado warnings issued for this outbreak yet there were 70 reported tornadoes, many of these we are finding out were long tracked tornadoes and multiple reports for the same tornado. This means the NWS is getting 4-6% of the warnings right and this was on a historic outbreak were the storms were actually producing tornadoes.
There were nowhere near 1000 tornado warnings issued during the outbreak. The total was a little over 200 tornado warnings from 16 NWSFO's.
http://www.easternuswx.com/bb/index.php?s=&showtopic=155131&view=findpost&p=2507699
As for the central MS having a high FAR, well I think many tornado enthusiasts know that JAN issues far more tornado warnings for marginal/weak storms than almost all other WFO's in the country.
Hi Rich, calling it a false alarm rate (FAR) to me is inaccurate, at least with the respect to the Dopper radar. The reason, the Doppler detects mesocycones not tornadoes, that's always been its job and in that respect it has a very high success rate. Unfortunately when the original project was lobbied it was being sold for wind shear, correct. That was justified off Fujita's original work concerning aircraft safety, down bursts and commercial planes falling out of the sky. It wasn't just about saving lives, it was about general trust from the public about commercial flying. Of course now we have on board radar in the expensive aircraft. Voices started saying these Dopplers will protect us against tornadoes....I remember certain people trying to tell the truth, but they were drowned out. Thus the billions of dollars was spent to upgrade the most populated areas of the nation first, finally getting down to isolated areas like Goodland. In the rare cases when we do see a tornado on the end of the hook what we are actually seeing is the debris ball; again much larger than the typical tornado. Even with the new and more powerful radars coming on line how does one see a 100-150 meter wide event at 65 miles distant. That is pretty much what we are asking that piece of equipment to do. Frankly I don't think it's possible even before we consider (a) curvature of the earth and (b) the +.05 degree tilt for environmental safety. With respect to the Doppler seeing the mesocyclone, we know that's accurate and as chasers we can verify it's rotating. For example, how many times have you sat on a rotating mesocyclone for 1-2 hours before that supercell produced a tornado. Remember the Hill City event last season? The supercell sat in that area for how many hours before it finally produced a condensation funnel to ground, at least four, would that be a fair assessment? Meanwhile, the Goodland Doppler sees a potentially tornadic mesocyclone the whole time and warning after warning is issued, most counting as false alarms. I wish the public understood the relationship between what the radar is doing (correctly) vs true tornadogenesis. Armchair chasing on Feb 5th I watched a lone supercell take over from a cluster in far NE LA, it was the first supercell of the day. It move into SE AR and immediately spun up a strong meso. In fact it had meso signatures early on and base reflectivity showed a classic supercell configuration. Yet that storm as threatening as it was traveled for at least 100+ miles I bet, before starting to produce real tornadoes. As it moved north other cells formed and trained that supercell finally moving into the Memphis-western TN region. It was there when they really let loose with tornado after tornado. To not put the warning on such a cell early would be tantamount to duplicating the infamous Fort Smith event where hours of warnings were issued prior to the destruction in that city...with no warning. Some supercells produce tornadoes within 30-45 minutes, others wait hours, but in the end the tornadoes are just as strong.
Unfortunately, daylight and roads available, coupled with extreme traffic congestion in Clinton did not allow us to follow the damage path of this tornado any further than approximately >10 miles northeast of Shirley, AR in Van Buren County and consequently this is where our own damage survey had to cease. We did not get to view the damage in the Mountain View/Zion/Highland areas.
KL
There were nowhere near 1000 tornado warnings issued during the outbreak. The total was a little over 200 tornado warnings from 16 NWSFO's.
http://www.easternuswx.com/bb/index.php?s=&showtopic=155131&view=findpost&p=2507699
As for the central MS having a high FAR, well I think many tornado enthusiasts know that JAN issues far more tornado warnings for marginal/weak storms than almost all other WFO's in the country.
NWS LZK has just issued another Public Info. Statement confirming that the AR tornado's path from Feb. 5th was 123 miles long - making it the longest confirmed tornado path since 1950. I imagine to top it one would have to look towards the Tri-State event and other historical markers.
http://www.srh.noaa.gov/lzk/cgi-bin/wxs1.php?pil=PNSMAIN&max=13
KL
I believe they are talking only about tornadoes that have affected Arkansas...there have been at least 3 with reported longer paths since 1990 elsewhere, including the previously mentioned 3-13-90 NE tornado at 124.0 miles, the Brandon MS F4 tornado of 11-21/22-92 at 128.0 miles and the already noted 11-23-92 NC F3 at 160.0 miles...whether these were adequately surveyed I have no clue. I would expect there were others from 1950 - 1979 with longer paths as well due to lack of surveys/knowledge of cyclical supercells.
RS
Gene,
I can't really speak for the motivations of the folks that started the whole WSR-88D project. However, by the time I joined the NWS in '92, the primary focus was on "20 minutes of lead time" for tornadoes. That's where our problems started.
The earlier Doppler radars were not collecting data unless a "big" day was expected, thus the early storm samples may have been biased toward high-end mesocyclones and tornadoes. Hence the old "50% of mesocyclones produce tornadoes" statistic. We've come to realize the fraction that produce tornadoes is much smaller, likely somewhere in the 10-20% range (depends on how you define a meso).
Gene is correct - the 88D almost never resolves an actual tornado, thus it's not fair to "blame" the radar for everything. In reality, the decision thresholds and situational awareness of the warning meteorologists play the biggest role in POD and FAR.
Rich T.
Hopefully Adam's project can have some success in defining a percentage of tornadic supercells and relate the percentages to their physical structural details.
Hey Brian,
That's interesting about that central NE storm with the 124 mile long track that may be one single tornado. I hadn't heard of that one - maybe I need to do some more research.
I'd edge away carefully from thinking that Tuesday's AR tornado maintained it's intensity for any significant length of time, however. It was certainly impressive to see a damage path continue uninterrupted for so far - but from our survey of the path today it was apparent that the vast majority of damage was in the EF-0 - EF-2 range. The track varied in width at several points - it was wide at Atkins, narrower at points northeast of there. Most notably however was the fact that - at points northeast of Atkins and southwest of Clinton, it was sometimes very hard to determine the damage path - the circulation appears to have got very diffuse and weak. It was still fairly wide - but the level of damage it was inflicting was greatly reduced compared to east of Atkins. Sometimes all we saw were some snapped twigs here and there. So - I would assert that this tornado went through several stages and morphs along it's path - and maybe have been multi-vortex in structure northeast of Atkins for a time. EF-4 damage is extremely hard to come by - as is EF-3. Mostly the tremendously long path consisted of nothing more than downed trees and sheet metal wrapped around fenceposts.
KL
I have gathered info from all the various damage surveys and have complied a list of the EF3 & EF4 tornadoes from the Feb. 5th/6th outbreak. Below is the link to the page on Vortex Times. There are still some details that have not been fully presented, and will update those as soon as they become available.
http://vortex-times.com/252608Outbreak
Per NWS LZK, they should make available later today a track map with map coordinates from ground/aerial survey data for the Arkansas EF-4 tornado from Tuesday last week. I will post a link when it is online.
It will be good to see this - because I am curious as to where the EF-4 damage was found along the track. I am thinking that this type of damage may have been located up in the Zion/Highland areas, which is the exact area we didn't make it to on Saturday.
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