Updraft: February 12, 2013 Archive

A sunny, mild Tuesday with a chance of snow Wednesday

Posted at 6:43 AM on February 12, 2013 by Bill Endersen (0 Comments)

February has brought us a lot of low overcast, that's for sure. At my house, the last mostly sunny day was two and a half weeks ago. Today will be quite different with partly to mostly sunny skies after some early-morning eastbound clearing. Scattered afternoon clouds should be about 2 miles up.

Temperatures will be pleasant for February. Afternoon highs will be mostly in the low 30s from the Twin Cities to Mankato and Rochester. Upper 20s will be the order from Redwood Falls to Brainerd to Duluth, Grand Rapids and Ely. Northwestern Minnesota will be a bit cooler with mid 20s around Bemidji.

Our next chance of snow will come in the form of an Alberta Clipper from the northwest beginning tomorrow afternoon. A couple inches of snow is likely across the northern half of Minnesota by tomorrow evening. The best chance of three inches could be around Brainerd to Mille Lacs. In the metro area, I expect up to an inch of white.

Bill Endersen

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How to photograph snowflakes

Posted at 9:00 AM on February 12, 2013 by Jon Gordon (0 Comments)

From meteorologist Bill Endersen:

Maybe you would like to take a closer look at or even photograph some of our flakes, such as those quarter-size flakes that fell on Sunday. Paul has been adorning his winter Updraft entries with exquisite photos of snowflakes, taken by Dr. Ken Libbrecht if I remember correctly.

Photographing snowflakes is extremely challenging. After they fall they break, clump, melt, evaporate and change shape due to vapor pressure gradients. The photography must be done in cold weather where even body heat can ruin a gorgeous flake. The lighting must be just right to reveal all the intricacies without melting the fragile flake.

So how did such a hobby get started? I'm glad you asked.

Wilson Bentley was a shy, curious, self-educated, bachelor farmer who lived in the small village of Jericho, Vermont. He was born in 1865 just as the Civil War was coming to a merciful end. As a youngster he enjoyed studying small objects through a microscope that his mother had used when she was a school teacher and he also became fascinated by snowflakes. So he tried to sketch them but was dissatisfied because he could not capture the layers of detail that he could see through the lenses.

Maybe, he thought, it would be possible to photograph these delicate objects of art. He somehow convinced his parents that they should buy a large bellows camera with a microscope objective lens so he could continue his studies.

He knew nothing about photography, so much trial-and-error followed as he learned to master temperature, lighting and the large dry plates (negatives that had to be made into positive prints) that far preceded film and digital photography.

During a snowstorm in January 1885, at the age of 19, he made the first successful photomicrographs ever taken of an individual snow crystal. Later he said that the greatest moment of his life was when he developed that negative and found it good.

Bentley continued his photomicrography every winter for nearly a half century until 1931. The variety of crystals from rather simple hexagonal plates to incredibly intricate stellar flakes and columns amazed him and led him to ponder the history of each flake in its "journey through cloudland."

After his death, 2453 of his black-and-white plates were published in the wonderful book "Snow Crystals" which is still available in softcover from Dover Publications.

The photos below show Wilson Bentley as an older man still using his original bellows camera and also samples of his life's work.

images courtesy:www.snowflakebentley.com

You might not have the equipment (or patience) to photograph snowflakes, but next time it snows go outdoors with a chilled, dark-colored towel. Catch a few flakes as they fall and take a good look at them through a magnifying glass. You will see a small but exciting world of crystal. And then give a nod toward Jericho, Vermont.

Bill Endersen

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Sunny Tuesday but snow on the way

Posted at 5:08 PM on February 12, 2013 by Bill Endersen (0 Comments)

That warm mid-February sun pushed the temperatures above freezing and melted some snow and ice today from the Twin Cities down through southeastern Minnesota.

The visible satellite photos this afternoon showed clear skies over much of eastern and southern Minnesota while clouds have moved into the northwest. Note the track of the Minnesota River in southern Minnesota and ice-covered Lake Mille Lacs in the center. Recent snows whiten the open terrain of southern and west central Minnesota but are masked by buildings and trees in the metro area.

source:NOAA

The real weather Tuesday was going on much farther to the south. Heavy snow has been spreading from the Texas Panhandle across western Oklahoma. Farther east, in the warmer air, heavy rain and spotty flooding have been a problem from Louisiana through Mississippi, Alabama and Georgia.

An Alberta Clipper with mostly light snow will head across Minnesota from the northwest on Wednesday. Here is where one of the forecast models "thinks" it will be snowing between 6 p.m. and midnight tomorrow:

source:NOAA/College of DuPage

Around two to three inches of snow is likely for much of the northern half of Minnesota during Wednesday-Wednesday night, but a few locations from around Mille Lacs into northwestern Wisconsin could pick up a bit more than that. The Twin Cities should be on the southern edge of this event with light snow beginning by late Wednesday afternoon and then accumulating around an inch overnight.

Look for a couple chilly days Friday and Saturday with highs in the teens, about ten degrees cooler than normal.

Following a warm-up beginning on Sunday we might slip a bit down the thermometer. Today the Climate Prediction Center issued a new six- to 10-day outlook for Feb. 18-22. It forecasts much of the western half of the United States and east into Minnesota to be colder than normal during that period:

Look for a pretty crescent moon to rise shortly before 9 p.m. this evening. It will be a waxing crescent with just 7 percent of the disk illuminated.

Bill Endersen

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