Core of coldest air next 24 hours

Respectable.

That's what MPR News Morning Edition weather chat cohort Cathy Wurzer called our cold air mass this morning during our daily weather chat. You might be tempted use some other words as you step outside today.

Some colors on the weather maps today are not found in nature.

The freezing line penetrates all the way to the Gulf Coast this morning. The core of the coldest air passes over Minnesota during the next 24 hours.

One saving grace? As the center of arctic high pressure moves over Minnesota, winds gradually diminish later today and Thursday. The next clipper rides southeast Friday morning with another dusting of light but potentially impactful snow.

Rock bottom

Temps stagger above zero today for a few hours, then retreat into sub-zero territory again tonight. We moderate into the weekend, but the overall temperature trend favors a cold bias through next week. February is determined to go out cold this year. Cue the moans and groans.

Saturday's American Birkebeiner in Cable and Hayward still looks cold with temps "warming" into the teens. Here's the latest trail report from the Birkie crew.

2.17.2015 (6:00am):  Groomed 1 skate lane from OO south to lake Hayward early this morning as we shuttle a PB south for main street work.  Also groomed the loops at OO.   Enjoy the skiing!

- chris and the groomers

MPR weather fan and fellow Macalester College Geography grad Ari Ofsevit has complied some interesting weather stats on the Birke. It turns out colder temps do make for faster conditions, but not by as much as you might think. There's a pretty high skill level in this race.

• The average high is 29º, the average low is 13º and the average 8 a.m. start temperature is 16º. Not too bad, eh?

• The coldest reported temperature at Hayward was in 2011 when it was -6º (and Cable was -10º). Four of the past seven years have seen the start temperature below 0º. The coldest DLH/EAU temperature was in 1994, when the average of the two sites was -6.5º. The coldest temperature reported by the Birkie for the start was -13º in 1974. And the course was uphill both ways that year, to boot. Pretty cold, eh?

• The Birkie has some luck, too. The 2009 race was held on February 21. Had it been a leap year, the race would have been on the 28th (last full weekend in February). That morning the low was -24º, and it was -17º at 8 a.m. (although it did reach in to the mid-teens later in the day).

• The highest start temperature was in 1999 when it was 35º as racers toed the line. In 2000, when the race was canceled, temperatures were quite a bit higher (those data are missing, but it was likely in the mid 40s). This is the only time the race has started above freezing; in 1981 it was warm but the race was postponed two weeks (except for elites and international races who lapped Mount Telemark six times).

• Since it’s late February, on sunny days the temperature often rises dramatically during the race. Four of the past eight years have seen the temperature rise by 20 degrees or more from 8 a.m. to the daily high. In 2008 and 2010 the temperature rose by 35 and 34 degrees, respectively. In 2008, the overnight low was -8º, it was -2º at race time, 22º at 11 a.m. and the high was 33º. In 2010, the overnight low was 3º, race temp 5º, by 11 a.m. it was 31º and the high was 39º. (Both these years were fine times to grab a beer and hang out on the lake.)This seems to be occurring more frequently in recent years, but that could be due to the data coming from Hayward and not EAH/DLH averaged.

• Snow is common during the race, falling about once every four races. Rain is less common, with only three races washed out in 40 years (including the 2000 cancellation). There have been two Birkie Blizzards in 1991 and 2001, each dropped 8″ of snow overnight and in to the morning of the start.

Milder light at the end of a long cold tunnel?

Scanning the maps for milder air is a national pass-time this time of year. The overall upper air pattern today looks a lot like the polar vortex driven pattern we endured last winter, just not as cold or persistent.

The National Oceanic and Atmospheric Administration's Global Forecast System has been insistent for three days now that a milder Pacific flow will develop by early March. Three days of the same pattern gives us a little more confidence that our deep cold days may be numbered as we depart February.

Here are the numbers. Keep in mind the longer range of the 16-day GFS shows more skill with temperature trends than individual days or precip events.

A string of days in the 30s with snow or rain chances the first week of March?

Stay tuned.