Posted at 8:32 AM on January 28, 2010
by Paul Huttner
They've been counting snow by the flake instead of the inch in St. Cloud this January.
Our climatologically snowiest month of the year has come up short of expectations for much of southern Minnesota. So far St. Cloud has measured only 0.9" of snowfall this month. With little more snow expected before the clock runs out on January Sunday, this looks like the 5th lowest January snow total on record for St. Cloud.
In the Twin Cities we've measured 3.1" so far this month. Our January average is 13.5" which gives us a deficit of about 10". By contrast Duluth has banked 14.7" so far this month. That's still 2.7" below average.
This season shows an interesting lack of snow in central Minnesota surrounded by heavier snows in the north and south. Here's a look at some area cities, snowfall and departure from average this season to date.
International Falls: 41.7" (-0.2")
Duluth: 52.9" (+3.7")
Grand Forks: 39.5" (+14.2")
St. Cloud: 21.6" (-6.0")
Twin Cities: 26.8" (-5.7")
Sioux Falls: 39.7" (+17.4")
Rochester: 39.1" (+8.7")
La Crosse: 30.3" (+4.8")
Our next shot at snowfall appears to be next Monday. An early look hints at the possibility of a 2" to 4" swath through much of Minnesota.
February: A bit milder?
The medium range forecast models are hinting at a slight moderating trend next week, followed by what could be a bigger warm up next weekend. Signs point to a lack of arctic air from late next week that may possibly last into Valentine's Day. Temperatures could return to readings several degrees above average by next weekend, the 6th & 7th of February.
So far we've felt 15 sub zero mornings in the metro this winter season. We may add 2 more by Saturday before temperature begin to moderate next week. That's 17 days, and the winter average is 30 days of sub zero air in the metro. It's looking more and more like we won't get there this year.
If we can get to mid February without any sub-zero air, the increased solar output, higher sun angle and rapidly increasing daylight make it less likely to sustain any arctic plunges that may come our way. My experience is that we usually see one or two more sub zero mornings in late February or early March, but I believe the worst of winter cold may be on the wane after this weekend.
Hang in there!
Posted at 4:12 PM on January 28, 2010
by Paul Huttner
Hopefully, it won't be long before wind chill babble disappears from the vocabulary of over zealous meteorologists in the Upper Midwest. These "lazy" winter days in Minnesota are like forecasting weather in Arizona. How many different ways can you say "clear and cold?" In Arizona months go by where you have to figure out yet another way to say "sunny & hot."
Believe it or not, there is a method to the madness of wind chill. People have observed for decades that you feel colder when the wind blows in winter. The NWS quantifies that feels like temperature on your skin through something called "the human face model."
People often ask me how wind chill is really calculated. If you're a math wiz, have a crack at the wind chill formula below.
Windchill (ºF) = 35.74 + 0.6215T - 35.75(V^0.16) + 0.4275T(V^0.16)
Where: T = Air Temperature (F)
V = Wind Speed (mph)
^ = raised to a power (exponential)
Now you know why I prefer to use the chart above.
The NWS updated the wind chill chart in the last few years to better reflect the actual heat loss on exposed skin in cold weather. A series of human trials were conducted in wind tunnel conditions with heat sensors attached to the faces of volunteers.
"The NWS Windchill Temperature (WCT) index uses advances in science, technology, and computer modeling to provide an accurate, understandable, and useful formula for calculating the dangers from winter winds and freezing temperatures. The index:
-Calculates wind speed at an average height of five feet, typical height of an adult human face, based on readings from the national standard height of 33 feet, typical height of an anemometer
-Is based on a human face model
-Incorporates heat transfer theory, heat loss from the body to its surroundings, during cold and breezy/windy days
-Lowers the calm wind threshold to 3 mph
-Uses a consistent standard for skin tissue resistance
-Assumes no impact from the sun (i.e., clear night sky).
Windchill Temperature is only defined for temperatures at or below 50 degrees F and wind speeds above 3 mph. Bright sunshine may increase the wind chill temperature by 10 to 18 degrees F."
It amazes me to see people these days wandering around outside without jackets in Minnesota when it's 20 degrees outside with a brisk wind. It seems our mentality these days is we can handle anything, who needs a coat? I have often said 20 is the new 40 when it comes to how Minnesotans dress in winter.