As I write, snow is still falling but beginning to taper off over the more western counties and will be ending from W-E this evening and overnight. In the meantime, the bitterly cold air of yesterday and today will only modify briefly before another surge of cold air arrives for Thursday & Friday and yet another surge early next week.
Up until recently, this has been a relatively mild winter and a relatively mild February. So what is going on?
It all goes back to the wind pattern aloft, or the location and strength of the jet stream if you will.
For example, notice the first map which shows the wind flow at around the 40,000' level back on Saturday evening, Feb 14. On that particular Saturday, we had a high temperature here in Tulsa that reached the mid-70s. But, notice that the winds aloft has the stronger flow coming off the Pacific, over an upper level ridge along the Rocky Mountains, and then drops southward with the strongest northerly flow east of us.
That is why we have been on the western fringe of the really cold air for much of the winter as the real brunt of it has been east of us.
The second map shows the wind flow aloft at the same level but initialized at Noon today. The more northerly component coming out of Canada is now headed our way, and then curves off to the east.
Notice that the second map also has a sub-tropical, or more southern jet, which is more W to E and is primarily positioned along or just south of OK. This is the track of the storm systems we had yesterday and again today.
This pattern brings the cold air further southward in our direction as opposed to the earlier pattern which was pushing the coldest air further east. This pattern also allows for storm systems to approach from the west bringing moisture up and over the colder surface air and giving us wintry weather as was the case yesterday and today.
These patterns shift around from day to day and the next couple of days will see a shift that will allow us to have a brief break for Tue/Wed.
Our skies will be clearing later tonight and lots of sunshine for Tuesday along with a light SW wind should get us into the lower 40s after starting off in the teens. Lots of sun on Wednesday and a light southerly breeze should get us well into the 40s after starting off in the teens to low 20s.
Then the pattern aloft will shift again supporting another surge of cold air that will arrive Wednesday night and we will be lucky to get above freezing for Thu/Fri.
There are also indications of another round of wintry weather, particularly on Thursday but that system does not appear to be very well organized at this time. Even so, some additional light snow is expected on Thursday and not much in the way of sunshine is expected right on through the coming weekend.
Gusty northerly winds on Thursday will diminish somewhat on Friday and from a more NE direction.
A brief return to a more southerly component will result in another moderating trend for Saturday and into the day Sunday before yet another surge of cold air arrives for early next week.
There will be a chance of what should be liquid precipitation over the weekend but that next surge of cold air may result in another chance of wintry weather early next week.
Not only that but the longer range guidance for the rest of that first week of March also looks cold and potentially wet. Notice the 6-10 day outlook maps for example, obviously winter is not over yet, not by a long shot.
So, stay tuned and check back for updates.