The Bad, The Good, and The Bad - and Maybe Ugly (12/29/20)

If you didn't get a chance to read the previous post I did on the 24th, click here.  

The advertised precipitation event I discussed back on the 17th, was just a tad slower in evolving.  Some of the precipitation began the night of the 27th with a band of snow that moved across west central Kansas into northeast Colorado, northern Kansas and into Nebraska.  The second wave of precipitation began last night and into this morning (29th).  Here is a precipitation map from late on the 27th until 7 AM this morning....

The rain, freezing rain and sleet that started overnight and continued through much of the day as it shifted east was not necessarily a single storm.  Rather it was a maxima in the upper level wind field that promoted what is called a "warm conveyer belt" and produced lift across the relatively shallow cold airmass aided by a surface warm front that was moving up into southern Oklahoma.   Here is the 24 hour precipitation map for Kansas, ending at 4 PM and provided by the Kansas State Mesonet...

So, the bad.  Well, this "significant" precipitation event was farther east than what would have been preferred for the drought area of the high plains.  That has been a common theme for much of the fall and now early winter.  Comparing the map above to what occurred around in early November...this pattern of precipitation was farther east by about 50 miles (in regards to the heavier precipitation).  These sharp gradients of very little to a whole lot have repeatedly occurred this past 70-80 days.

The Good?  It was another significant precipitation generating weather system for the central U.S. that was "right on track" as far as long range predictability.  This boosts confidence going forward for other potential impacting events.

The bad or maybe ugly?  The same area that has missed the big events may miss many of storms going into spring.  The caveat is that some of the forcing areas around the northern hemisphere generating these storms have changed slightly.  My hope would be the pattern could shift west a little, with time.  

Looking at this mornings upper level chart....

                                                          500 MB - 12/29/20 at 12 Z

The main upper level storm was located across western Arizona.  Typically this would be a nearly perfect location to impact the high plains.  However, because of upper level ridging across the north Pacific and something referred to as Rosby Wave Propagation across the entire Pacific basin, this upper level low is predicted to take a track closely resembling the red arrow.  That is, the upper level low will intensify/amplify as it dives across northern Mexico before lifting rapidly northeast and then north across the mid-Mississippi Valley.  That will result in a tremendous amount (remarkably high) of precipitation (mainly rain)!  However, that track also keeps the precipitation out of the high plains.  IF, the storm were to take a track annotated by the green arrow, then we'd be in good gravy.  That won't happen (99% chance it won't).  Here is the outlook from the Weather Prediction Center (and keep in mind this in addition to what fell today)...

The western edge may be a bit too far west. 

You may also notice lots of precipitation across the west coast.  Great for them!  It also is an indication of an active upper level pattern across the Pacific.   I'm seeing indications of a developing extended east Asian jet stream (very energetic winds coming off the mainland due to very high pressures across Siberia).  That could very well impact the central U.S. once again around January 9, give or take a day.  That should be the next significant chance of precipitation after this Thursday/Friday (again east of the high plains).

Merry Christmas!

 In the previous post on the 17th, and it was a long one, I discussed a potential significant storm centered on December 27, give or take a day or two.  There was a lot of information in that post and you can read it here.  Ten days away and I put that date out there.  At the time there were NO computer forecast models with anything at all through the end of the year.  As late as 21st there was a lot of social media from various folks discussing above normal temperatures and below normal precipitation with NO storms through the end of December.   I was patiently waiting for those computer models (and the forecasters) to finally pick up on the possibility.   So, here we are on the 24th and I'm sure a lot of you have already heard the chatter about a significant storm next week.  Is it a slam dunk at this point?  No, not yet because of the complexity of what is going on with the jet stream, especially across the Pacific.

Here is a snapshot of the atmosphere late this afternoon....

The winds aloft across the Pacific are active and very complicated.  There are several source regions for energy, both tropical, mid-latitude, and higher latitude influences.  The red X's are disturbances (or storms) aloft with varying intensities.  The one that has my attention I labeled X1 near the Aleutian island chain of Alaska.   This disturbance in the wind field "should" begin to amplify as it approaches the west coast.  If not, there may be another development.  Regardless, amplification of the wind field should occur across the western U.S. starting late in the weekend and the result will be a widespread precipitation event for the central U.S., including much of the plains.

What makes a forecast with any detail impossible at this point is that it is uncertain which disturbance will become the main storm.  How amplified will it be?  What track will it take?  Exactly when does it move across the plains?  How cold will the airmass be?  Will it be cold enough to support all snow?  Freezing rain?  Sleet?  Thunderstorms?  Wow, there are MANY possibilities!  At this point, it's best to follow weather.gov as we get closer to the event.  You will see many computer solutions on social media, and THAT I can be certain about.  Some of these computer model solutions I've seen have ridiculous amounts of precipitation.  Some solutions (from the American model) keep much of the high plains dry while others are very wet.

As for that date of the 27th that I mentioned in that blog posting on the 17th...it looks like there could already be a little freezing drizzle as early as late on the 27th although the main "show" will probably be later on the 28th into the 29th.  

Here is an "early guess" from the Weather Prediction Center on precipitation amounts incorporating this potential storm.  At this point, it's just a broad brush of possible amounts.  Again, details are not possible at this point.  

If I get a bit of time, I may try and update this blog late Sunday or early Monday.

The pattern has started to repeat - I think (updated 12/17/20)

This one will be a long one....

The previous posting was on the 25th of November (you can read that one here) and I waited to update with a purpose.  As many readers are aware, the repeating or cycling of the "new" weather pattern that develops in the fall and the periodicity of that repeating is not known until the first cycle has ended.  Looking closely at the northern hemispheric upper pattern, I believe pretty strongly that the second cycle has begun and has a relatively short cycle length. So, now there should be slightly higher confidence of what is possible going forward.  However, there is still a small chance that the cycle time may be up to 12 days longer which completely screws up the timing of  forecasting certain high impact events.  I'm going forward right now based on the shorter time scale.

In that previous post, I ended with: "Looking ahead I suspect that mid-December ought to get really interesting based on a hunch, thinking the wavelength is around 55 days give or take."  I now believe the wavelength (cycle) is on a shorter time scale; perhaps as short as 48 days, but that would have still led to an active mid-December for at least southwest Kansas and into western Oklahoma.  As most of you are aware, unless you've been in a coma, it has been pretty active this December.  Now, I do see a problem at the moment.  The geographical region targeted by these storms has been relatively small in areal extent.  Not all locations of the drought area has benefited which continues to be a concern.

For December, there has been what would now be considered a near record amount of snow at some locations.  Look at the closeup of how much snow has fallen in the 3 storms for December!

The 3 storms have targeted basically the same area but with a tight gradient (especially to the north) of very little to a whole bunch! 

The drought map shows improvement where it snowed significantly.  Here is the latest map ...

After this last storm on the 15th, the snow field was pretty impressive viewing from satellite....

Back to the earlier storms, here is a map of snowfall from December 3rd and the view from satellite from that particular storm (sorry I changed the color scale)...

And here is the snowfall map from the storm on the 12th/13th and notice the target area is basically the same....

Imagine trying to forecast for a particular county.  On the 12th/13th event, the snow amounts across Ford County (Dodge City) were from around 2 inches to over 12 inches!

So, now what?

One key element through the end of December will be the Arctic Oscillation.  It has gone strongly negative (very cold air building up in the high northern hemispheric latitude region).  It is also projected to go even more negative by the end of the month. I haven't seen it projected to be this negative in a long time.  But, we'll see if it actually does go that negative.

Essentially this cold air buildup which is reflected in the negative index will help to energize the polar jetstream even more than it has been.  I expect that there will be rapid and significant changes upcoming.  The first impact is what produced the snow across the area a few days ago on the 15th and eventually the mega ice and snow storm across the eastern part of the U.S. (several reports of 4 feet of snow) yesterday and today.   The next two systems impacting the central U.S. will be fast moving with little or no moisture to work with so I don't believe we'll see much precipitation, if any, and only a glancing blow of cold air.

So with a pretty good idea of the cycle length, if I'm right about the time period, then here is what I expect...

1) There should be a pretty good warmup leading up to Christmas.  Now, the snowpack will definitely impact (or mitigate) the amount of warming.  Those areas of the high plains without snow cover will see a few days next week that should be pretty mild!.  Timing of particular fronts will always be a challenge across the high plains, regardless of weather patterns in place. 

2) The next chance for a significant storm will be a day or two centered on the 27th (Dec).  However, if that storm does occur, it is impossible to predict if it will be the southern, central, or northern high plains.  Based on what has been going on this month and with the projected phase of the Arctic Oscillation, I would favor the odds to be closer to southwest Kansas.  The balance of December after the 27th and into the first few days could be pretty cold!

3) Mid-January could be pretty active (8th-20th) but confidence of that period is still very low.

4) I would put high odds of several more BIG storms this winter, including storms in February AND March.

BTW, in the numerous presentations I've done the past few years (and also mentioned in this blog), at Dodge City there had never been more than 3 years in a row with annual above normal precipitation (based on the current 30 year average).  Last year (2019) ended as the 6th year in a row with above normal precipitation.  Just based on laws of averages, that seemed highly unlikely to occur.  So what about making it 7 in a row?  Believe it or not, 2020 will end up with above normal precipitation once again (even if no more falls)!  Absolutely incredible!  Seven years in a row!  If there had been just a bit more precipitation in 2013, then this would be the 8th year in a row!  Records began in October 1874 at Dodge City.  The closest I could find that had this many years in a row of above normal precipitation was from 1922 through 1928 when 5 of 7 were above normal (3 in a row) with the other 2 pretty close to normal.  You know what followed?  The next 11 years (in a row) were below normal on precipitation.  Laws of averages...it's real.

More statistics....

This current weather pattern cycle began around Oct 7.  The amount of precipitation that has fallen in Dodge City from the 7th up through yesterday, the 16th, is the 19th wettest on record (147 years of records).  Of the top 20 wettest periods (10/7 thru 12/16), here is what occurred the following spring and summer...

Out of those 20 years, the following spring (Mar-Apr-May) was drier than normal 9 times.  Of those 9 years the spring was drier than normal, the following summer (Jun-Jul-Aug) was wetter than normal 6 times and the other 3 were not too much drier than normal!  If the following spring was wet, the majority of the summers afterwards were dry.

So, to recap.  I think there will be plenty of opportunities for more moisture going into spring.  But my concern is that those areas largely missing out may continue to miss the majority of those chances.  Typically though, as the jetstream reaches it's maximum intensity (on average) storms become larger in areal extent and intensity.  At least there are chances going forward.

Later this winter I'll jump forward with an outlook for the spring and summer.  I would like to see another cycle of this weather pattern and nail down the actual periodicity. 

I'll try to get an update done right before Christmas to update the thoughts of that late December opportunity of a storm, if it occurs.

A Precipitation event! Updated 11/25/20

 In the previous post on the 20th (read it here) I discussed the system that would occur on the 21st and said "In general, amounts will be a quarter of an inch or less.  But there will be bands of precipitation (relatively small) where some will get closer to 1/2 to 3/4 of an inch."  Here is what fell....

Just that one storm is encouraging going forward as it will return later this winter and spring.  

The next system I discussed was to occur Monday with another possible later in the week, based on energy across the Pacific.  It appeared the first system would impact mainly Nebraska and the eastern half of Kansas.  As has been the case with a couple of the systems this fall, the first one amplified way more than expected and thus slowed down.  The precipitation occurred yesterday and was MUCH more than expected! This is yet another encouraging sign!  However, what is still very concerning is that the hardest hit drought area keeps missing out on the heavier precipitation.    Here is a map of the precipitation that occurred yesterday with this storm....

There were reports of over 2 inches of rain across parts of Saline county and up in to north central or northeast Kansas.  And, for the second time this month, there was a lot of lightning and thunder.  That is unusual for November.

Because the upper level low was so compact and energetic it was capable of producing an area of snow.  However, the area was very small compared to the area of precipitation that it produced.  A cold source really was not available (colder yes, but not snow-like).  But, it still produced the snow!  The largest amount I saw was 6 inches with numerous reports of 2 to 4 inches...lesser on the edge of the snowfield. 

So, as I've mentioned a zillion times.  The weather pattern of upper level troughs and ridges and orientation of the jet stream will start to repeat or have very similar characteristics.  I still haven't seen evidence of this repeating but it has got to be getting close.  The pattern started setting up that first week of October and I'm going to say centered on October 7.   Looking ahead I suspect that mid-December ought to get really interesting based on a hunch, thinking the wavelength is around 55 days give or take.

Later this weekend or first of the week there should be another system but at this point it looks like it will stay way south across Texas.  Long range computer models are getting screwy late next week and I think that might be related to an active jet stream across the Pacific.  All bets are off beyond about 5 days.  

I'll try and update around the 1st.

Brief update - 11/20/20

This will have to be brief.  In the last update on the 13th (read it by clicking here) I ended with "There is enough energy across the Pacific Ocean basin that I see a possibility of another amplified system centered around the 21st.  That might be our next shot at precipitation (20th, 21st, 22nd).  Before that, much warmer weather is expected next week."

At this point all is on track.  It was definitely warmer!  In fact, temperatures were 15 to 20 degrees above normal!  That is pretty significant!  The precipitation event expected does look like it will be primarily tomorrow (Saturday the 21st).  In general, amounts will be a quarter of an inch or less.  But there will be bands of precipitation (relatively small) where some will get closer to 1/2 to 3/4 of an inch.  The rain will be widespread and maybe as far west as the Colorado border but again it won't be much.  

The Pacific jetstream moving into the Conus is energetic and there should be a few more systems by Monday and perhaps again later in the week.  The first one will bring the majority of the precipitation to Nebraska, Iowa and the eastern half of Kansas with just widely scattered "stuff" to western Kansas.  Neither system (Saturday and Monday) will do much to alleviate the worsening drought.  

Here is the outlook from the Weather Prediction Center through the end of the next week but it appears they are discounting any late week system....

The possible system towards the end of the next week may or may not be that significant.  I say that because being a week out in the pattern like this it is virtually impossible to predict the time, space and intensity.  But, just know that there "could be" an amplified system.  

As far as the returning systems I discussed in the previous post, I just don't know yet what that repeating cycle length is or will be.  I have a hunch that it is between 50 and 60 days. 

If I don't have an opportunity to update this blog next Wednesday (25th), then I won't get to it until around the 1st.

Update - November 13, 2020

 Sigh...

I had attended to post an update last week.  But, I had to change out laptops and lost a lot of data links and programs I use to keep up on the weather.  Most have been restored.

The most recent precipitation event on November 9th was a bit of a surprise,.. at least it was not expected 3 or 4 days out.  It originally had looked like the system would be too fast and not amplified enough to bring precipitation to areas west of southeast Kansas.  As it turned out, the system amplified into a closed low over the 4 corners region and was then capable of drawing moisture north from the Gulf of Mexico.  Unfortunately for areas hardest hit by the drought very little or no rain fell.  Here is a map of precipitation for the event....

At several locations there was even severe sized hail (1 to 1 1/4 inch in diameter).  So, the system was very energetic.  In this new northern hemispheric weather pattern that developed in early October, this is the second time a strong upper low amplified across the west and benefited at least a big chunk of the central U.S..  Yes, farther west there hasn't been that much.  That IS a concern.  But at the same time, I'm slightly encouraged that there have been these 2 events.  

So going forward into winter and next spring, these 2 episodes will return.  More than likely they will be impacting events (blizzards for the cold season and severe weather in the warm season).  However, what still has me concerned is that there will likely be long stretches of no precipitation going into spring.  Those periods may also be associated with above normal temperatures and lots of wind.  That's not a good combination. 

In the previous post I did on the 29th of October (read it by clicking here) I mentioned November 10-15 being a suspicious period that models were converging on that could bring some weather.  Unfortunately, there just isn't enough amplification of the jetstream to bring precipitation for the high plains.  It looks like southeast Kansas will be as far northwest as we can expect with this one.  Just more wind and warmer weather for the high plains.  Here is the outlook from the Weather Prediction Center through the end of next week....

No help for the drought area....

U.S. Drought map

So, as I've mentioned way too many times, the weather pattern that forms in early fall will begin to cycle at some point.  I don't know if that will be every 30, 40, 50, 60 days, etc. until I see the whites of it's eyes (I can recognize similarities across the northern hemisphere).  There is enough energy across the Pacific Ocean basin that I see a possibility of another amplified system centered around the 21st.  That might be our next shot at precipitation (20th, 21st, 22nd).  Before that, much warmer weather is expected next week.  

I'll try and update later next week.

Updated 10/29/20

 If you didn't have a chance, please read the post I did on the 22nd.  Click here.

In that post the discussion centered on the cold and then the potential storm for mid-week (which just occurred).  The cold air was certainly very cold.  I said it wasn't going to be record setting but I probably should have looked a records a little closer.  Low temperatures didn't set a record but the very cold calendar day high temperatures did set a few records this past Monday.  There were high temperatures that were only in the teens (I was expecting 20s which for the most part is what occurred).  The attention then turned to this mid-week system.

Here is the important part I discussed in that posting on the 22nd..."But....will it amplify and follow the blue line track?  This would occur in concert with a building ridge (the blue zig-zag) across the eastern Pacific because of the upper low.  That would mean a more favorable storm track and possible significant precipitation event for the central U.S. by mid-week.  This would also be a part of the pattern that would repeat at some frequency during the winter and spring."

The digging of the system I was talking about developed into a huge closed low aloft and well west of the high plains.  It's what I call an anticyclonic wave break.  This event has very SIGNIFICANT implications on this years pattern.  A similar event occurred in September (the previous widespread precip event).  Even though that was part of the former weather pattern, what forced that storm is likely what forced this current storm.  So that part of this new weather pattern will repeat again going through winter and through the spring months (and even into the summer).  However, and as I mentioned in that last post, the big question will be "how often".  Maybe every 30 days - maybe 60.  Unfortunately I won't know until it occurs again.  Plus, the next time it could be farther north...or maybe farther south!  Or maybe too far west or east!  But, what is encouraging is that it actually happened. 

This current storm, that has now moved east, "could of" been MUCH more significant!.  First, if it wasn't for the very cold air moving all the way to the Gulf, the extent of the precipitation would have been bigger and the amounts would have been even heavier.  Second, the hurricane that went into Louisiana also "robbed" the plains system of moisture to work with.   The gradient of who got a lot and who got very little was very tight.  Without the aforementioned hurricane and very cold air, I bet the precipitation would have been farther west and north.

Here is a map of what fell yesterday....

And here is what fell this past week (including Monday and Tuesday's snow and freezing rain) - this map includes additional reports and radar data... 

Look at the snow that fell around the high plains, especially across Texas and Oklahoma!

So, what's next?

The very cold air is not likely to return for at least 2 weeks.  It will be mostly milder with an occasional cold frontal passage (first may be late in the weekend) but no significantly cold air is expected.  Any precipitation would likely remain across the higher terrain of the Rockies .  Here is the expected precipitation (from the Weather Prediction Center) through next Thursday...

Long range forecast models are starting to converge on a possible through (dip in the jet stream) about November 10-15.  That could lead to warm and windy followed by a return of some pretty cold air.  Precipitation would be highly dependent on the amplitude and orientation of the jet stream.  That is impossible to predict at this point.  Again, the weather pattern is just getting set up and return intervals of specific orientations of the jet stream just can't be predicted at this point.  Keep your fingers crossed that we get those amplifying jet streams or anticyclonic wave break storms more frequently and to the west.  I wouldn't count on a frequent occurrence but hopefully enough that others that missed the precipitation this time will benefit the next. 

I'll shoot for an update around the 5th.