Updraft: December 11, 2012 Archive

Cold, but bearable; quiet much of the week

Posted at 6:31 AM on December 11, 2012 by Craig Edwards (2 Comments)
Filed under: Cold, Winter 2012-13, Winter storms

Monday brought the coldest temperatures of the season to much of the state. If you were standing at a bus stop that's likely not breaking news to you. The mercury at the Twin Cities International Airport was on a slow decent toward zero when clouds moved in last night.

The temperature dipped to 2 degrees at MSP, which is the coldest temperature since a low of of 1 on February 11th.

As the daylight continues to grow shorter, combined with the low sun angle and snow cover, it becomes increasingly difficult to warm the surface of the northern landscape.

Maximum temperatures today will remain well below normal, but a moderation is in store for Wednesday and Thursday. For today:

20 F Monday's maximum temperature in the Twin Cities

-20 F Monday's minimum at Roseau, MN

The far southwest corner of Minnesota and Sioux Falls, SD missed out on much needed moisture from the weekend snowfall. Snow also bypassed the drought area of northwest Minnesota and eastern North Dakota. Grand Forks, ND and Sioux Falls, SD both reported a snow depth of only two inches on Monday morning.

7.76 inches Moisture deficit for 2012 at Fargo, ND

9.73 inches Moisture deficit for 2012 at Sioux Falls, SD

The National Weather Service in Chanhassen posted this map of the total snowfall for Saturday and Sunday:

Source:NOAA/NWS Chanhassen, MN

Snowfalls of this magnitude and coverage are not rare, but based on the winters we've experienced of late, this was quite a snow dump, particularly in central Minnesota and into western Wisconsin. The type of snow depth that puts a smile on the face of skiers and those that enjoy a snowmobile ride.

Be cautious if you wish to take a snowmobile across a lake. Snow is insulating the formation of ice and there wasn't much depth to the ice layer prior to the weekend snowfall.

Don't look for much in the way of additional snowfall the remainder of the work week.

As a meteorologist, I'm frequently asked, "When's the next chance for snow?" It comes with the territory. There is a tendency to over reach by believing long term computer models. The models did pretty well on the last system.

We'll be keeping our eye on the computer runs for possible snow on Saturday and Sunday. The emphasis is on possible.

GFS model valid at 6 p.m. CST Saturday.
Source; NOAA/COD

You'll note on this model forecast for Saturday evening the relatively mild air extending into northern Illinois. Here's an interesting weather highlight for 2012 out of Chicago, which set a record yesterday for the longest period without measurable snowfall:

PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE CHICAGO IL 401 AM CST TUE DEC 11 2012 /501 AM EST TUE DEC 11 2012/

...LACK OF SNOWFALL RECORD BROKEN AT CHICAGO...

MONDAY DECEMBER 10TH MARKED THE 281ST CONSECUTIVE DAY WITHOUT
MEASURABLE SNOWFALL AT CHICAGO...SURPASSING THE PREVIOUS
CONSECUTIVE DAY RECORD THAT HAD BEEN SET IN 1994. THIS IS NOW
THE LONGEST PERIOD OF TIME WITHOUT MEASURABLE SNOWFALL IN CHICAGO
ON RECORD. THE LAST DAY WITH OFFICIAL MEASURABLE SNOWFALL IN
CHICAGO WAS MARCH 4TH. ROCKFORD CURRENTLY STANDS AT THE SAME
AMOUNT OF DAYS...WHICH IS THE FOURTH LONGEST SUCH STRETCH IN ITS
PERIOD OF RECORD.

Here's a visible satellite image captured late morning on Monday giving you a good idea of the snow cover -- the forested area of northeast Minnesota may mask some of the snow depth:

Visible satellite image, Monday morning.
Source: NOAA

Landscape outside the Eden Prairie weather lab late Sunday afternoon:

Image: Craig Edwards

(2 Comments)

Snow will hang around; more to come this weekend

Posted at 3:50 PM on December 11, 2012 by Craig Edwards
Filed under: Cold, Snow, Snow cover, Winter 2012-13

The high quality snowflakes that accumulated on Sunday have already settled several inches. Chanhassen measured 13.5 inches on Dec. 9. By 6 a.m. today the snow depth was down to 8 inches.

Snow that accumulated in my yard on Sunday has settled about 4 inches from the 12.5 inches measured on Sunday evening.

How do you measure snow?

It's much easier when the snow falls with little wind as it did Sunday in the Metro. Observers are instructed to take about 10 spatial measurements and average them for a best-derived snowfall estimate. Official snowfall measurements are to be taken at six-hour intervals, beginning at 6 a.m. The total of the measurements is considered the daily snowfall or the snow storm total.

Water equivalent is collected in a gauge, as the one shown here.

Image:Craig Edwards
For display only. My gauge is positioned in a well-exposed area!

During the winter season, the funnel and measuring tube are removed so the snowfall can collect in the 4-inch gauge. Once the snow has stopped, the observer takes the gauge indoors, melts the snow and pours the water into the measuring tube.

We are early into the meteorological winter, which began Dec. 1. But snowfalls can clobber us in late autumn, as we experienced in the Halloween Blizzard in 1991.

Snow lovers were cheated last winter. This recent dump of snow should be sufficient for cross country skiing and snowmobiling for some time. Here's a link from the
Minnesota DNR on tracking conditions on the recreational trails.

Look for another very chilly night. Temperatures will drop off quickly this evening over the snow cover with nearly calm winds. Rising temperatures are expected in the early morning hours.

Tonights minimum temperatures.

Still tracking the potential snowmaker for the weekend. Models are tracking the next low pressure a little farther to the south. You'll recall the low pressure on Sunday traveled pretty much along the Iowa/Minnesota border.

The GFS model run from 6 a.m. CST paints this forecast of the surface low for Saturday evening. Masked by the precipitation, the low is in southeast Iowa. The heaviest precipitation, shown for this six-hour period, over southeast Wisconsin, may fall as a cold rain.
Source:NOAA/COD

Our colleagues at the National Weather Service in Chanhassen present this nice graphic of the potential snow for Saturday.

In case you missed it, the low at the Twin Cities International Airport late last night was 2 degrees above. It was the coldest temperature recorded at MSP this season. Monday was the first day this month when the temperature average was below normal.

Craig Edwards