2019-08-13: South-Central Minnesota Wall Clouds & Tornado

Aug 18, 2016
13
4
1
Mankato, Minnesota
Before I go any further, I have a question. This was the 2nd time that I was caught off guard in 2019.
By off guard, I mean that the site I check for storm prediction SPC Day 1 Outlook
only depicted the area I live in as (TSTM-light green) a 10% or higher probability of thunderstorms.

As far as I know, even as the storms were active, NOAA never moved the rating above TSTM probability for my area ?
I understand that none of the tornadoes in Minnesota last Tuesday, were high EF rated, or long duration/destructive ones, but they were tornadoes nonetheless.

Can someone recommend a better storm prediction site ?



Like I said earlier, I was caught off guard, so the first I was aware of any severe weather in the area was when I heard the sirens going off in town.
(Mankato) Around 3:00. Looked out the window to the north east & saw why they were going off.
I won't bore anyone with unnecessary details, but I do need to explain one thing before you watch the video.

The video of the tornado at the end is bad for 3 reasons.
1a- It was a substantial distance away, which means I had to use the zoom.
1b- When heavy zoom is used, the built-in stabilization feature is basically rendered useless.

2- On top of that, the sun was out. It was at my back, which caused extreme glare on the camcorder screen, making it almost impossible for me to see what I was filming.

The tornado was SE of Janesville Minnesota.

All that being said, I'm thrilled to have seen a tornado that day!
 
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Reactions: Adam Lucio
Shots looked good. Awesome video if you had a tripod. SPC is more of a single generalized information source for chasing. I have better luck on the marginal days. :) Keep a look at the models and forecasts. I think the NAM had a few cells over the southern MN area, but I don't have the data in front of me now.
 
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Reactions: Steve Frederick

GPhillips

EF4
Jul 8, 2004
301
32
11
Topeka KS
It looks like you were on the west edge of a marginal area for severe storms forecast by SPC day 1 forecasters, with a 2% tornado probability area forecast just to your east over EC and SE MN and western WI. There's even a mention for the possibility of brief tornadoes in the Northern Plains/Upper Midwest in the text discussions from them on the 8 AM, 1130 AM and 3 PM outlooks.


That is really not a bad forecast for a marginal event in late summer.
 
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Reactions: Steve Frederick
May 18, 2013
374
291
11
You're not looking at the correct SPC outlook. The one you posted was issued at 1:01z on 8/13 (8 PM CDT 8/12). It says it is valid from 1z on 8/13 (8 PM CDT 8/12) to 12z on 8/13 (7 AM CDT 8/13). The tornados reported in MN on 8/13 occurred between 18:18 and 22:03 UTC (1:18 PM and 5:03 PM CDT) - over 5 hours after the SPC outlook you posted expired.

Here is the outlook the SPC issued at 5:39z on 8/13 (12:39 AM CDT 8/13) that is valid from 12z 8/13 (7 AM CDT 8/13) to 12z 8/14 (7 AM CDT 8/14):

day1otlk_20190813_1200_prt_small.gif

As you can see it is a lot closer to what happened. As the day went on SPC refined it further (all outlooks from 8/13 can be found at Previous SPC Convective Outlooks Issued on : ). By the time they got to the 16:30z outlook (11:30 AM CDT), they where pretty close. Here is how the 16:30z outlook finished for the day:

day1otlk_v_20190813_1200.gif

Don't feel bad - it is very easy to look at the wrong outlook and we all have done it. If you look before the 12z (7 AM CDT) issuance, the main graphic on the SPC page is still the day before.