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Scott Nelson
01-26-2009, 08:08 AM
My son and I were looking at the sky today up here in the chilly Northeast. Temps are in the teens but a cloud bank seems to have a classic beaver tale to it. Although this of course isn't connected to a storm that's going to produce anything more than a few flurries, it prompted the question from him that I could not answer. "What the coldest temp a tornado has been reported in?" Anybody know?

Shane Adams
01-26-2009, 08:38 AM
I have no idea if this answer is correct, but I'll throw February 22, 1975 into the mix. Six tornadoes ravaged parts of southwest Oklahoma, including five F2s. I'm not certain, but I believe the AG temps were in the mid 30s-low 40s range. Even more impressive was the fact these tornadoes were nocturnal.

It snowed the next day (if I'm not mistaken) while rescue/clean-up teams were in action.

Scott Weberpal
01-26-2009, 09:49 AM
There have been numerous events in recent history when a very late/very early season tornado occurs along a boundary with temps in the 30s north of the boundary and in the 50s or 60s south of the boundary. As long as the storm is feeding on the airmass south of the boundary, technically a significant part of the storm can be in very cold air while tornadoing. I can think of a handful of upper-midwest events when there were blizzard conditions and inches of snow literally hours after a tornado. The 11/11/1911 tornado outbreak is an extreme example....

"Nine tornadoes were reported in the states of Michigan (http://en.wikipedia.org/wiki/Michigan), Illinois (http://en.wikipedia.org/wiki/Illinois), Indiana (http://en.wikipedia.org/wiki/Indiana), and Wisconsin (http://en.wikipedia.org/wiki/Wisconsin). An F4 tornado hit in Janesville, Wisconsin (http://en.wikipedia.org/wiki/Janesville,_Wisconsin) killing 9 and injuring 50. Within an hour of the tornado, survivors were working in blizzard conditions and near zero temperatures to rescue people trapped in debris (http://en.wikipedia.org/wiki/Debris)." Source - Wikipedia

Chad Cowan
01-26-2009, 11:57 AM
Mike U caught a nice tube on November 11th with a cold core setup in SW KS. I believe air temps at the time were under 50 degrees.

http://www.underthemeso.com/blog/

http://davieswx.blogspot.com/2008/11/mike-umscheid-catches-november-wedge.html

Greg Stumpf
01-26-2009, 01:50 PM
I photographed a non-supercell tornado on Lake Ontario in Oswego NY in December 1982 while there was light snow falling and temps were in the mid 20s. Scans of those old photos here. Low-contrast was due to snow, so I enhanced the contrast for these scans.

http://members.cox.net/gstumpf/snow%20tornado%201.jpg (http://members.cox.net/gstumpf/snow%20tornado%201.jpg)

http://members.cox.net/gstumpf/snow%20tornado%202.jpg (http://members.cox.net/gstumpf/snow%20tornado%202.jpg)

Jeff Snyder
01-26-2009, 02:15 PM
I, Gabe Garfield, and Justin Walker were on a tornadic supercell in NW OK on March 20th, 2006 (it was a "cold-core setup"). The temperature at our location was in the mid-40s (with an actual wind chill that must have been in the 30s), and there was snow (with 1/2 mile visibility) reported about 30 minutes after the tornado ~45 miles northwest of the supercell. In fact, we experienced what I only can call graupel falling on the backside of the storm after the storm. It felt and looked like dime-sized snowballs or low-density partially-melted hail. Below is a pic of the small wall cloud and tornado... This is looking southwestward, with the RFD clear slot visible cutting around the west (e.g. left) side of the low-level meso:

http://www.tornadocentral.com/chasing/2006/03202006/img_1743-01_std.jpg

A very brief (and likely not the best) sfc analysis I did a couple of years ago is given below... Note that the temps (T and Td) are given in celsius, and the cyan-colored T just NE of the surface low represents the location of the tornado; another tornado occurred near the location of the cyan-colored 'T' near Marshall. It's a rather complicated surface map, with several fronts and boundaries evident (best seen by looping the sfc data). The contouring of SLP makes me think another sfc trough could be analyzed N of the warm front, but oh well.
http://www.tornadocentral.com/chasing/2006/03202006/2218_mesonet_with_fronts_2.png

Again, the temp and dewpoint are given in degrees Celsius! I have another analysis in degrees F at http://www.tornadocentral.com/chasing/2006/03202006/2218_mesonet_f.png if you don't want to convert C to F (though I don't like the placements of fronts and troughs much in this one).

More pics on chase log -> http://www.tornadocentral.com/chasing/2006/03202006.php

Scott Nelson
01-26-2009, 02:18 PM
WOW!!!!! That is insane! I figured that a tornado might form in the cold IF the weather to the South of the front was REALLY REALLY warm. But never did I think one could still drop once the temps got into the 20's! Figured there simply would be enough updraft because cold air is so heavy! I'm guess I'm still learning. REALLY cool info guys and thanks for these photos Greg and Jeff!!!

Jonathan Behle
01-28-2009, 12:53 PM
So a followup question I wonder to this is, can we have freezing rain with a tornado? Ive seen fairly intense rain and lightning with the temperature around 27 or so..

I remember last January in Wisconsin with the tornado outbreak, piles of snow in parking lots were visible as that was going on.. But of course the ground mostly was bare at the time..

afischer
01-29-2009, 09:56 AM
January 7, 1992 had a "chilly" cold core tornado event in central Nebraska (including an F2)... haven't seen surface data for it but am guessing it was similar (with respect to "relatively" modest temp and dewpoint at the surface) to the March 20, 2006 one. When you've got -3C to -7C at ~700mb in a classical cold-core type of set-up, 40s dewpoints at the surface is often sufficient to result in some pretty ridiculous low-level CAPE. Add higher terrain in (northeast and eastcentral CO are a hotspot for cold core events) and the effects on low-level CAPE can be even more surprising.

Boris Konon
01-29-2009, 02:58 PM
On 11/24/05, a pair of mini supercell tornadoes occurred on coastal Maine
near Brunswick after a few inches of snow had just fallen.

http://www4.ncdc.noaa.gov/cgi-win/wwcgi.dll?wwevent~ShowEvent~577846
http://www4.ncdc.noaa.gov/cgi-win/wwcgi.dll?wwevent~ShowEvent~577847

Snow ended about an hour before the event as a warm front pushed
through. Tornadoes occurred shortly after 18z w/ sfc temps in the low 40s.
Not that cold, but it was the 850 and 500 that struck me as unusual. Rather
low heights w/ basically a piece of the polar vortex moving into the area!

http://www.spc.noaa.gov/obswx/maps/500_051124_12.gif
http://www.spc.noaa.gov/obswx/maps/500_051125_00.gif
http://www.spc.noaa.gov/obswx/maps/850_051124_12.gif
http://www.spc.noaa.gov/obswx/maps/850_051125_00.gif