Tuesday, December 20, 2022

Brief update

This will have to be very brief.  My NWS is coming to a close and I have been swamped in that preparation.

The expected cold mentioned in the previous post has come to fruition and will culminate with brutally cold and wind Thursday and into the early weekend.  Any meaningful snow will concentrate on the midwest but won't help in any drought concerns as it will be very dry.  The biggest issue will be the cold (actual temperatures and wind chill indices), as shown below.

The upper air pattern is ideal with the cold buildup across the higher latitudes of North America and is being unleashed south as the blocking high had developed across Greenland.  Here is the upper air map as of this morning...

Expected temperatures Friday morning (and keep in mind Thursday temperatures will not be much warmer and wind chill indices will be extremely cold)...

Warmer weather is expected the last few days of December.  January - I need to find some time to look it over.

BTW, here is a map of precipitation that occurred yesterday by a little weak weather system.

I'm not sure I will be able to update until after the first of the year - as a Non-National Weather Service but as a consulting Meteorologist.  Changes are coming!

Friday, December 9, 2022

The pattern may be set

In the previous post on 11/23/22 (read it by clicking here) the headline was "another swing and a miss?".  I also discussed that this year's pattern was not quite set, or so it would appear.  With the system this week (southeast of the area across mainly Oklahoma but a secondary moving well north) and the system moving by this Friday night and Saturday (again mainly southeast of the area), I believe I have a pretty good idea of the nature of the pattern.  Is it concerning that much of the high plains has been left high and dry?  Absolutely.  But with the changing of the seasons (fall into winter, winter into spring, and spring into summer), the pattern will shift around enough that it won't be totally gloom and doom.  Now to time it.

The system(s) the past 2 days brought good moisture to Oklahoma again (and into the Corn Belt).  Here is a map of that precipitation. 

During the past 2 weeks there was "some" precipitation farther into the plains, but not a lot.

The biggest weather news this next week will be a monster storm that is going to impact much of the central part of the country with a blizzard across Nebraska and the Dakotas and severe convective weather farther south and east.  There will be a big concern for a possible outbreak of tornadoes across the Mississippi Valley.  For the high plains (at least the central and southern high plains), it looks like more of the same with dry and way too much wind.  But....

In the past few meetings and presentations that I have been doing, I mentioned the second half of December could be active and very cold.  I've expected this for several weeks because of some connections to the tropics with the higher latitudes; possible blocking of the jetstream;, and a buildup of snowcover across the northern hemisphere. One thing I look at in a shorter time frame (less than 30 days) is the indices of the Arctic Oscillation and the North Atlantic Oscillation. 

It's not unusual for these indices to go strongly negative.  When the Arctic Oscillation goes strongly negative, it is often followed by a deep intrusion of Arctic air into lower latitudes.  Sometimes it's across Europe or Eurasia and sometimes into North America.  It just depends.  When the North Atlantic Oscillation goes deeply negative, there is usually blocking of the jetstream across the Atlantic and into Greenland.  When this happens weather systems tend to slow down and move more meridional. But, when both the AO and NAO go negative, there is quite often a major intrusion of Arctic air into North America, including the U.S..  That is one clue that December is about to get frigid.  Then top it off with the snow that has built up across the northern hemisphere...

BTW, that area of snow cover across the northern hemisphere had been above record levels and still is above the 56 year mean.  Interesting. 

With all this going on and with the pattern that is setting up, the jet stream flow is going to become (or has become) very energetic and volatile.   After this major storm moves by early next week, the remainder of December will, on average, be colder than normal with periodic episodes of snow (including snowfall for the high plains).  The way I see it, many locations across the central and northern U.S., will have a white Christmas or at least the odds favor such.

As far as precipitation, here is what the Weather Prediction Center is expecting through the end of next week.

That is definately a concerning image for the central and southern high plains, especially knowing that there is going to be more wind.  The periodic snow I'm expecting towards the end of the month will help a little.  I would expect those opportunities to repeat a couple of times going into spring.  

My gut feeling going farther into 2023?  It will be a “normal” winter, active spring and probably a dry and hot summer – all subject to updates as the pattern becomes evident.  

With me wrapping up my career in Meteorology with the NWS, I'm not having much time to update this blog but I will attempt to do so again next week.  As mentioned, a month ago or so, changes will be coming to this blog.  More later.