Upper-Midwest winter storm on Friday

[Joel Wright]

I was hoping for maybe a few rumbles of thunder today. With a current Td of 17°(!!) it's going to have to be all dynamics for any chance at any thunder. That's one bad thing about this time of year. Moisture is usually very hard to come by. Even when moisture does get here, it's usually VERY shallow. There's nothing environmental either to help out, like leaves and anything evapotranspirating. We have to rely soley on advection at this point in the game.

There's some very impressive bands of heavy snow on the north side of this system. There has to be some terrific snowfall rates in some of those bands. What's really interesting is the VERY sharp cutoff to the northern edge of the snow near MSP. It would be interesting to drive south into that. It looks like you would just drive into a wall of snow!

 

[Bill Schintler]

Satellite animation of the storm

1-km visible animation (NASA site):

http://www.ghcc.msfc.nasa.gov/GOES/goeseastconus.html

Select "animation",
25 images to loop,
quality=100%,
zoom="high",
map="standard",
map color = "black"

Click on the Sioux Falls area. This may take a long time to load on
a slow connection. Once it loads and starts animating, increase the
speed of the animation a few notches, click "faster" a few times.

An animation like this tells a 1000 words. A few noteworthy
features today: in MN the northern extent of the stratus deck (low
clouds) is seen repidly moving to the west, while the cirrus shield
(high clouds) lifts off to the north east. Note the fresh snow in
the wake of the storm in SD. Note the "dry intrusion" now working
into western IA. Note the high cloud tops developing in north-
central IA and lifting NE towards the IA/MN border. This convection
is a result of very strong upward vertical veloticies as a
result the vort max moving in. Juxtaposed with this is a pocket of cooler
temperatures moving in at the mid and upper levels in association with the upper low. Picture in your mind a moisture "conveyer belt" moving northward through eastern IA and then lifting along the isentropic surfaces from northeastern IA into southern MN. This moisture feed rotates counter-clockwise around the upper-low while continuing to rise (the TROWEL). This is the region of the heaviest snowfall.

- bill