Cold Releasing Its Grip?

You read that right, we're looking at a break from arctic cold that has plagued the area since early December.

First, a look at winter so far.

It's been 9th coldest start to meterological winter (Dec. 1st - Feb. 28th) through today, averaging a temperature of 8.7°.  It's the coldest since we started the winter averaging 3.9° in 1978/79 through the same date.  The normal temperature during winter up to this date is closer to 17.7°

During that stretch we've had 41 days reach temperatures subzero.  18 of those days eclipsed -10°.  Just this morning the starting temperature was -19°, tied for the second coldest air temperature observed this season, only behind January 6th when it was -23°

In comparison, last year only bolstered 12 days with subzero temperatures.

While there has been several days with snow, none have been particularly overbearing when it comes to amount of snow.  The most snow in any one day was Jan. 18th when 4.1" fell.  So far this season, 30.1" of snow has fallen, behind the average winter by 5" but ahead of last year to date by 7".  (Remember the end of last year was snow heavy ending with 74"!)

So it hasn't been a lot, however, the cold has ensured a snow pack of 12"+ across the area.  And potent Alberta Clippers packing blizzard criteria winds have caused quite the ruckus too. 

There's been one common reason to why temperatures have been so cold.  The answer can be found with the jet stream several miles up in the atmosphere.  The jet stream is like a highway for storm systems.  These storm systems translate through the layers of the atmosphere to the surface.  Since December 5th, the day of our first subzero temperature of the season, the average position of the jet stream has been diving straight into the US from Canada and running south of the upper midwest, bringing most of our storm systems in from Canada.  You know them as Alberta Clippers.

This pattern set up a strong persistent ridge over the western US, western Canada and Alaska.  Alaska, which by no surprise, is normally shivering in that arctic air, but not this year.  Unprecedented warmth has been the rule, forcing the arctic air out of Alaska and moved southward by the jet stream

The following map shows the temperature anomaly from December 5th - February 9th.  Notice Alaska has seen temperatures some 4° to 6°C (7.2° to 10.8°F) above normal for the period.  Conversely, Minnesota and Iowa have been 3° to 6°C (5.4° to 10.8°F)  below normal.  That matches observed data. (7.9° below normal thus far)

If you've noticed the extended forecast, it doesn't show any sub zero temperatures!  The big reason again can be found in the jet stream as the pattern has shifted.  Here's a look at how the jet stream is expected to sit for Wednesday.   Notice how the jet no longer kinds down from the north west letting Canada and Alaska back in on the coldest of the air.  This allows our storm systems to move in more-so from the Pacific Ocean, rather than originating north of the arctic circle in Canada and Alaska.  As you would guess, this would mean we'd miss out on the coldest of the air as it retreats to the north. 

Looking out in the long term, this pattern that is more west to east should prevail, so we'll miss out on the arctic air for some time.  It's not a guarantee to say it won't return again.  But for now we can find some relief in knowing warmer temperatures are on the way.  After all, the warmest temperature we've seen so far in February was 20° on the 1st.  We should break into the lower 20s tomorrow.  More 20s, even 30s will be possible from time to time.

In days 8-14, the Climate Prediction Center is FINALLY showing some promising results after this potent winter.  It's boasting an above average temperature trend for the first time in months.

While we warm up, it will take some southerly winds to get us there, so the warmest of days will likely have a bit of a breeze to them.  Causing the breeze, are disturbances passing through from time to time.  And these disturbances will bring some periodic snow.  Eventually as temperatures warm enough into next week, it may even mean a wintry mix or even rain being possible.

Here's the extended outlook.

Tonight: Mostly cloudy, with snow developing after midnight. Lows in the single digits above-zero then rising towards sunrise. Winds SW 10-20 mph.

Wednesday: Snow early, wrapping up by mid morning. Mostly sunny afternoon.  Highs in the lower 20s.  Wind: W 5-15 mph.

Thursday: Partly cloudy.  Highs near the freezing mark.

Valentine's Day: Partly cloudy with a slight chance for light snow early.  A little cooler.  Highs in the upper teens.

Saturday: Mostly cloudy, with a slight chance for snow. Highs in the upper 20s.

Sunday: Partly cloudy. Highs in the lower 30s.

Monday: Mostly cloudy, with a slight chance for a light rain/snow mix. Highs in the middle 30s.

Tuesday: Mostly sunny.  Highs in the upper 30s.

Storm Tracker 6 Chief Meteorologist
Chris Kuball