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27 April 2008

Cool/rainy has turned to cold/snow.

Rain and storms covered the region on Friday. Snow and wind brought winter back to the region on Saturday.

The upper-low that was responsible for all this wet weather was spinning over northern Minnesota, bringing instability across Wisconsin and the UP of Michigan. Wisconsin's first tornado watch was issued on Friday across the southern third of state (Watch #0232).

While there was large hail and one tornadic storm towards the south, there were two cells that produced large hail in the north. At its closest approach, one of the two passed 50 miles to my east, and I captured it on radar (to the upper right). It started down in Oneida county and trekked almost due north, bringing Severe Thunderstorm Warnings to Onedia, Vilas, and Gogebic counties. My radar screenshot was captured at 20:08 and shows the storm as it is about to emerge over the waters of western Lake Superior.

Hail reports.

As the storm formed in Oneida county, it produced several reports of hail:

1.75" Heafford Junction (1 mile N)
1.75" Harshaw
1.75" Lake Tomahawk (3 miles NW)


The storm continued it path north and entered Vilas county, leaving 1.75" hail at Manitowish Waters at 21:18 (first storm report to the left).
The storm was still producing hail as it moved offshore into Lake Superior. 1" hail was reported northeast of Wakefield in the UP county of Gogebic (second storm report to the left).

Storm Reports from 4.25.08 can be found on the SPC site here.

Quite a strong low pressure system.

I pulled two graphs off my personal weather station (to the right). The top one shows measured outside temperature from the last seven days, while the bottom shows a combination of barometeric pressure and highest daily wind gusts from the same time frame.

Wednesday (4/23) I recorded the highest temperature of the year, so far, at 74.9 degrees. Four days later, the low temperature this morning was 26.1 degrees. This is a drop of almost 50 degrees! Average highs for this time of year should be around 55 degrees, we're a bit below that right now.

Pressure shows the low pressure system as it passed by - a huge dip down to 29.33 "Hg on Saturday. The lowest pressure coincides with the highest wind gust I measured, 28 mph. My location is sheltered, but Ashland's airport measured gusts in the upper 30 mph range. The winds were similar across the entire region as the low pressure spun northeastward.

Snowfall from Friday evening through Saturday night.

Over a foot of snow was reported on the Iron Range northwest of Duluth, where Winter Storm Warnings had been posted.
The rest of the area saw either mixed precipitation fall, or only a trace amount of snow.

This radar image (to the left) is from 11:12 on Saturday morning, and shows the large area of light snow falling in northeastern Minnesota and northern Wisconsin. Wind barbs on the ASOS metar plots shows sustained winds around 20 mph. I experienced brief bursts of heavy snow and wind, followed by several minutes of weak sunshine. The pattern repeated itself throughout the daytime hours on Saturday.

Snow pictures.

Through most of Saturday the snow stuck only to branches, the wet and warmer ground melted snow on contact. This picture (to the right) shows the Hemlock trees in the driveway's roundabout.


I received a total of 0.98" of rain and melted snow from this storm system (from Thursday through Saturday night). This was about half of what was originally forecast, therefore the Flood Watch that was posted for the area was allowed to expire without any reported problems.

By mid-afternoon, the snow began to stick to elevated surfaces and was beginning to turn the grass white. This picture (to the left) is looking east across the front deck.

Accumulations never rose above a trace as the snow continued to melt on contact, but it was enough to make the landscape look like winter.

In fact, Saturday felt exactly like a wet and cool mid-November day. Wet and brown leaves covered the ground, winds were gusty and cold, and snow was falling. A typical November day up here.

Towards evening, the snow stopped melting on contact as the temperature fell below freezing. This picture (to the right) is looking north towards the garage. Snow was covering the garage roof as well as some grassy surfaces and a few places on the gravel driveway.

By this morning (Sunday), all the snow has disappeared! Temperatures have risen above freezing around 10:00 and the clouds are letting blue sky and sunshine through now at 11:00. Winds are calmer this morning, but still a chilly breeze from the west.

Looking ahead.

The forecast from the NWS calls for a high temperature of 40 at my location with a slight chance of more snow/rain showers this afternoon. It looks like we'll finally start to warm up on Tuesday, with a return to average temperatures on Thursday.

9 comments:

  1. Nathan, I've put your data into the "Winter Season Duration" formula. Preliminary findings suggest your Winter started Dec 2, 2007 and currently is in day 5 of transition from Winter to Spring. The transition started on Apr 23 assuming your observations from yesterday, today, and tomorrow find you in the same position (above 32F and less then one inch of snowdepth). If so, Apr 28 will be your last day of Winter! It would suggest then, that your Winter lasted 146 days, Dec 2 thru Apr 28.

    If your outcome doesn't match mine lets review our definition! Perhaps I misinterpreted the data. Hey, welcome to Spring, potentially. :)

    I can send you the spreadsheet I updated if you are interested. Also, just for my verification, what were your observations from the 26th and 27th?

    Fun stuff!

    ReplyDelete
  2. Ummm...about that GRLEVEL3 stuff. I downloaded a trial but I can't get it out of the Atlanta area!
    Has this happened to you?

    ReplyDelete
  3. Scout, to fix your problem, go up to the top menus and pick SITE and choose SELECT from the drop-down menu. From there you can pick any radar site in the country.

    Or, you can click on the radar screen on the Blue Dot next to a nearby radar site. The four-letter ID of the radar sites are next to each dot.

    If you need any more help, just email me direct at my gmail account! I'd be glad to assist in any way I can!!

    ReplyDelete
  4. OSNW3,

    26th: 26.6/36.3
    Trace of snow fell.
    Water Equivalent and Rainfall: 0.15".

    27th: 26.1/44.6
    No snow fell.
    No precipitation measured.

    28th: 28.5
    Trace of snow fell overnight.

    I put my observations into a modified Julian Date (i.e. July 12, 2007 = Day 1). I agree with Dec 2, 2007 (i.e. JD 144) and Apr 23, 2008 (i.e. JD 287) as being the dates of the definition. 287 - 144 = 143 days. I'm not sure how this is three days different than your count (146).

    I'm a little torn as I think about tweaking the criteria. I was thinking about the large taste of Spring (74.9 degrees) last week. Conversely, I'm now thinking twice with more snowflakes and very cold temperatures today and yesterday.

    I'll keep thinking about it, maybe getting above 70 degrees with less than an inch of snow should bypass the rest the definition. Or maybe new snow fall, even a trace, should delay the day count. Today should be the first day of Spring then, but if more snow falls today, might tomorrow then be the first day of Spring? Just thinking about loud.

    Of course, it's reasonable that a little Spring occurs in Winter and vise versa as things begin a transition. In this case, the definition fits my weather perfectly.

    I like the definition, as it is, as a measuring stick. From nothing we've formed something. I guess, after my rambling, I like it :)

    Yeah, please do send me your spreadsheet update. I like the idea that today is the beginning of Spring!

    ReplyDelete
  5. Our days may be off because I am not calling Apr 23 as your last day of Winter, but after the transition, Apr 28 being your last day of Winter.

    Right now, today will be your day if you break 32F and an inch of snow doesn't accumulate.

    These flakes down here are gigantic! Still!

    ReplyDelete
  6. I guess the Excel duration day counter didn't account for LEAP YEAR.

    From and including:
    Monday, December 3, 2007
    To, but not including:
    Monday, April 28, 2008

    It is 147 days from the start date to the end date, but not including the end date

    Or 4 months, 25 days excluding the end date

    ----

    Now I suppose my duration days are goofed by one day as well if Excel is using a 360 day year. I'll go back and check. I suppose we should decide on the actual end date.

    Should the duration count the end date or exclude it?

    ReplyDelete
  7. Ah, my bad. Too many dates and numbers on the spreadsheet. You're using 6 days transition?

    Wouldn't this make Dec 3rd the first day of Winter for me then?

    Reading through NWS Duluth's discussion, it's not out of the realm of possibility that another closed upper-low may bring a weather repeat towards the end of next week. T-Storms, Rain, Snow.

    Freeze warnings through Iowa, northern Illinois, and Missouri tonight. Probably that record low temperature will be broken in central Missouri tonight. That's pretty far south for this cold pool of air at the end of April!

    ReplyDelete
  8. Should the duration count the end date or exclude it?

    I think the last date of Winter should be included, followed by the first day of Spring. Right?

    ReplyDelete
  9. Your spreadsheet
    My spreadsheet
    (if you are interested)

    ----

    I am thinking it should be included as well. So each of our durations will be bumped up another day.

    I use this Date Duration site to calculate!

    ----

    I was thinking that the sixth day of transition was the DAY Winter/Spring begins/ends.

    DATES! AH! Yeah we need to come up with a standard. Take a look at the spreadsheets and let me know what you think.

    ReplyDelete