Pages

22 November 2008

Numbers from the last LES and sub-zero temps.

Up to 2 feet of snow fell from the last lake effect snow event (Wednesday & Thursday).

I pulled together all the snow reports from NWS offices in Marquette (MI), Green Bay, and Duluth (MN) from the two-day event and listed them in this spreadsheet screenshot (to the right).

The left column lists totals from Wisconsin while the right from the UP of Michigan.
The highest totals I found were 25" in Luce County, MI and 13" in Vilas County, WI.

I received only three days' worth of flurries from the event.

To better answer Derek's question, the winds were very favorable for a few locations but never veered (turned clock-wise) northerly enough to bring heavy snow across the entire south shore of Lake Superior.


With winds staying northwest, a small section of the western south shore received some heavier snow (6-13"), and the eastern south shore was hammered (25"). For the Wisconsin shoreline to actually see some high snowfall amounts from the Lake, the wind needs to turn to the north or northeast.

The forecast for the last event called for some northerly winds but they didn't materialize.
I threw the map together (above) to give a rough idea of the most favorable directions for certain locations to see the highest amounts. I've never spent time in the Keweenaw Peninsula, but I'd image that any wind direction - except due southwest - would bring lake-enhanced snowfall.

Many things go into making lake-effect snowfall, several that are beyond me, the ones I do understand: the difference (delta T) between lake surface temperatures (warm) and air temperatures in the lower few thousand feet (cold but not dry) need to be greater than 13 C, an inversion helps avoid atmospheric mixing - but too low squashes the convection, and the winds need to stay blowing but not above 20 or 25 mph. The last several events were forecast to be better than they actually turned out, not all of the variables always come together perfectly.

After the clipper and cold front, some cold air settled in Saturday morning.

This morning I measured a low temperature of 4.8 degrees just after 7:00. The last time our low temperature dipped below 5 degrees was on 8 March, 2008, 260 days ago.

The NWS forecast called for most of northern Wisconsin to be at or near zero by dawn, but several places fell lower than expected.

With the help of GRlevel3, Paint, and MesoWest, I put together this map (to the right) of measured low temperatures across the region.

The coldest area was centered on the Saxon and Montreal river valleys: -12 in Upson, -14 in Wakefied, and -18 at Saxon Harbor. In fact, for 10 hours overnight (from 20:00 until 5:00) Ironwood, MI was the coldest official reporting location (ASOS) in the continental US. Then Eagle River, WI took over until 8:00.

9 comments:

  1. thanks for better explaining how Lake effect snow works, now I understand! wow -14.F thats very cold could you find any photos of the 20 inch snow?

    ReplyDelete
  2. The only pictures I can find are from WGN's blog:

    http://tinyurl.com/5hjo4m

    ReplyDelete
  3. Sweet entry, N. I had asked my buddy in MQT to take photos, but nothing has entered my inbox as of yet. I do believe him when he said Marquette had 22" and further east at his camp they had 2-3'. LES is so localized that getting a true perspective of what has transpired is so hit and miss. Skilling stumbled upon some sweet photos though! Good old Steve Brown! I've been up to Houghton a handfull of times back in 1995-1996 when I went to NMU and for weekends at a time it would never stop snowing. It was amazing. I'll do my best to dig up some photos from my friends who went to school at Tech from back then. I am now on a mission!!! Again, sweet entry! I really enjoy your perspective.

    ReplyDelete
  4. I truly know the variability from winds and snow off the Lake! Not only the snow to worry about but then the winds that move it around into back-breaking drifts!! I understand (but haven't personally seen) the need for two-story houses up in the UP to have a door on the top floor. I've always wanted to get a picture of the 'double stop sign' with an octagon at 8' and then another on the same pole at 16'.

    Still haven't had a "good" LES snow event here on the Bayfield Peninsula. Haven't had a decent winter low pressure snowstorm either. Next week looks to bring a slight warm-up.

    Looking forward to you hopefully finding some snow pics from up there. Let us know what you find!!

    Thanks J :)

    ReplyDelete
  5. Double story stop signs thats sounds like a funny Idea how useful! yes we would Love to see some photos OSNW3!

    ReplyDelete
  6. them photos are amazing there! It is neat what climates you can find in areas even across Wisconsin the northern part and Upper MI is under snow while down here in my and osns area we have not seen a snowfall over 1" Nathan did you know I have gotten Lake effect snow once from Lake Superior before ? Just what was left from a shower, but it was still neat to think about came from the lake!

    ReplyDelete
  7. Yeah, D, I remember you wrote on 8 November about a radar screenshot I posted. I would imagine that if the winds are right, you would get some snow from the lake that far south. I know Phillips sometimes feels the lake-effect snow too.

    ReplyDelete
  8. I found some beautiful snow pictures from out West - Yosemite National Park in California - on a fun blog. The pictures can be found on this link:

    http://geekhiker.wordpress.com/2008/02/27/yosemite-in-winter-trip-day-4-mirror-lake-half-dome/

    ReplyDelete
  9. Derek, you may also be interested to look through these photos from Wisconsin:

    http://www.jsonline.com/multimedia/photos/Weather.html?c=y&index=31&page=26

    The first picture that the link will take you to is from just north of where I grew up. That's the East Fork of the Chippewa River. I've canoed that river downstream of where this picture was taken.

    ReplyDelete