Date: 010618 Braham, MN, and Siren, WI tornadoes
All times UTC
MM=Mobile mesonet

The field crew: Albert Pietrycha
Elke Ueblacker
Christina Hannon
The chaser formally known as "Matt" Biddle


Brief SUMM
Time of Braham, MN tornado ~0025-0028.

The crew continuously observed the Siren tornado from 0105-0126 before being forced to plunge into the forest; resumed full 
visual contact at 0143.  The tornado approached 1/2 mile wide at the sfc.
Time of adult black bear crossing road at a right angle to the tornado, 0138 (seriously!).


Long SUMM
Started out from Yankton, SD at 1500.

We intercepted the back (rear) periphery of the tornado cyclone associated with the Braham, MN tornado at ~0025.  From our vantage point 
within the wrapping rain curtains, the tornado had dissipated by 0028.  We were able to detect a portion of the funnel embedded within the 
rain curtains but unable to confirm a debris shield; vegetative debris did however rain down around/over us.  Before we saw the back of the 
tornado we drove past scattered fresh, minor tree damage (F0).  At that time we were not certain if the damage was from the night 
before (MCS?) or from the tornado.

We then headed east on Hwy 70 and positioned beneath the updraft base.  The MMs performed transects across the southern periphery of 
the tornadocyclone.  A broad thin rain curtain wrapped around the MMs as tornadogenesis commenced ~1.5 mile east of Grantsburg, WI, 
1/4-1/2 mile north of HWY 70, at 0106.  We drove east out of the surface debris circulation and began the first of several attempts at 
stereo photogrammetry.  As the Siren tornado raced east at 40-43 mph, it quickly evolved from a small cone, to large cone, then a fat 
stove pipe, and finally a true wedge where the tornado approached a 1/2 mile wide at the sfc.  We busted east ahead of the tornado now 
traveling 1/4-3/4 mile off our rear bumpers.  The tornado was _highly_ visible due to superb contrast and amazingly, several open fields.
Hwy 70 in that area rides a shallow ridge and trees were cleared well away from the roadside (about 50 feet).   The large debris shield 
was impressive, full of large trees and structures being flung up and outward.  Hwy 70 turned north for a 1/2 mile stretch a few miles 
west of Siren; which was daunting indeed.  The tornado track was continuous to Siren and entered the west side of the town at 0125.  

We continued east on road B, now surrounded by dense forest, with only the clear slot visible over our heads and a few north viewing 
"windows"; violent wrapping rain curtains persisted.  We were able to make a final attempt at an intercept once we turned north on 
road H.  The tornado crossed from west to east ~1 mile in front of us at 0143 (it is possible this may have been a different tornado); 
two nervous white tail deer ran low to the ground across the field to the road.  We aborted the intercept at this time as the tornado was
tracking down our only remaining east road option.

Observations
Since 60-80 foot hard wood trees were at one point being snapped by the RFD south of HWY 70 and tossed on the road, we had to stay 
immediately ahead of the RFD jet max.  I was concerned that if the RFD jet caught us, trees would have pinned us down on the road and 
then we would have been in trouble; 3-meter MM winds along the periphery of the RFD jet max were 34 m/s.

The clear slot along the SRN and ERN (forward) edge of the tornado appeared to have eroded cloud mass all the way up to the bottom of 
the anvil cirrus.  The temp/dewpoint was nearly uniform ahead of the tornado; ~27/22C.  

Photogrammetry is very difficult to do in a debris filled, wet RFD.  I was soaked (no big deal) and hit a few times by small debris (ouch).

If the tornado we witnessed at 0043 was the same tornado that hit Siren and was continuous east of Siren, the path length was at least 
28 miles. 

All four MM participants heard a continuous low frequency oscillating "roar" when stopped for photogrammetry work immediately downstream 
of the tornado.

A sincere thanks to my morning forecaster Jason Lynn and our two nowcasters Jim Johnson and Marty Venticinque.  Marty worked his tail 
off in aiding me in positioning the teams along the warm front.

The MM data and digital video will be analyzed ASAP.

--Alnado