Thursday, January 31, 2013

Is Winter Over?




I'm getting this question quite a bit lately... is winter over?  There are very strong indications the first half of February will be well above average in terms of temperature.  We'll have a cold day Friday, then temperatures will trend well above average.   I suspect IF we have anymore winter, it will not be until after February 10th.  I'll explain below with maps.

Let's look at winter so far.  January will end up almost 4 degrees above the average and December was almost 7 degrees above average.  We've had 2 snows so far.... 1 HUGE and the other very minor.  Those two snows have almost tripled our yearly average and I don't think it's over... wink, wink. 

Here's an interesting fact, Little Rock has not had an official temperature in the single digits since early February of 1996.  As we get later in the month, that statistic will be hard to change as we begin to head into spring.  

By daily low temperature, 5 of the top 10 coldest were in February!  The coldest was Feb. 12th, 1899 when Little Rock dropped to -12.  

By daily high temperature in Little Rock, 3 of the top 10 were in February.  

In terms of snowfall, 3 of the top 10 snowiest months were in February.  3 of the top 10 snowiest days were in February as well. 

I don't like long term forecasting.  I define that as anything past the 7-10 day period.  However, I'm going to show you some of the things I have noticed with the data.  This winter is completely different than last winter as I see POTENTIAL for more cold and POTENTIAL for more wintry weather.  Last year, you may remember I declared winter over in mid February.  That was a risk that paid off.  This year I will go out on a limb and say there are more fun and games we'll have to deal with.  Remember though, I think readings will be well above average through at least the 10th, then we may see some changes.  I'm going to show you the past 4 runs of the GFS valid February 10th.  This is an attempt to show you what's happening over the Pacific Ocean.  The downstream effects over the United States are far from certain, but with a pattern developing out there like this, I will not write winter off yet.  One other point of interest, long range experts are talking about another stratospheric warming event.  I talked about that in early January.  These tend to shove arctic air masses to the south, but as I cautioned you then, I'll caution you now.  Where those cold shots are directed is the big question.   Will it be the western, central, eastern United States, or a combination?

Check out the maps below.

This is the 6Z run of the GFS valid February 10th at 500 mb.  We're looking for ridges and troughs with the black solid lines.  Look over the eastern Pacific off the coast of California.  That ridge, if strong enough, can work its way to the north and dislodge the cold air over western Canada and Alaska.  When that happens, it's usually forced south into the trough downstream over the United States.  Where it's directed is a question at this time.
The 00Z run shows the same thing on Feb. 10th and it's a bit more amplified.  That means it's poking up to the north and able to dislodge that colder air.
And the 18Z run from yesterday valid Feb. 10th, the same eastern Pacific ridge.
And there it is again on yesterday's 12Z run
And now my favorite long range model, the European shows it as well.
In summary, we see some consistency with possible ridging across the Pacific.  The downstream effects are not known and each model run says something different.  Because of this, climatology as explained with the February records, and another stratospheric warming event, I will not write winter off at this point and go out on a limb and say there are more interesting things to blog about this month!

3 comments:

donaldwaynebrown said...

there will be more winter!

Mitchell McDill said...

I have noticed that this winter seems to have large daily swings in high temperatures. Several times the high might be 60 for a couple of days, then drop to 45 for a day, then go right back to 60the next day. Whatever happened to the 3-5 usual degree variance per day!

Tam said...

I've seen snow as late as Easter in Arkansas so I say never say never. We've also had a few snow and or ice events on Valentine's Day...I remember because they ruined plans I had at the time. :)