Sunday, May 31, 2020

Update - May 31, 2020

I'll just start this one with - I have some bad news.  Let me go back to the fall when this weather pattern set up.

Back in October when this weather pattern got established and as fall progressed, there was a pretty good signal that there were going to be periods of active weather systems impacting the western high plains.  But, as is often the case for this area, weather systems require gulf of Mexico moisture to become efficient precipitation producers.  Those that have paid close attention; during the fall, winter and early spring there were many cold front passages and weather systems near by.  Sometimes the systems were wet, but mostly they were merely windy and dry.  As we entered spring, these cold fronts pushed the gulf moisture well south and even some times out into the Gulf!  As weather systems approached, the gulf moisture was late in returning, thus much of the area missed out on beneficial rain/snow.  Then to make matters worse, the elevated mixed layer (EML) - essentially the warm layer aloft (Capping Inversion) was a bit strong so that showers and storms formed farther north and east.

I thought April would have at least average precipitation.  But that thought was dead wrong.  I blame it again on the gulf of Mexico moisture being shunted too far south and east (and the airmasses were a tad chilly).  Then for May, I was expecting a particularly active period from May 10-28. That didn't work out too well although there were plenty of systems - just a lack of gulf of Mexico moisture again.  I've rarely seen a May with a lack of surface moisture so often!   In the post I did on May 6, I started stating that uneasy feeling that the high plains were going to be on the edge of the more significant precipitation.  I repeated that once again in the following blog post on May 14.  Now, I'm REALLY worried!

For the past 2 years, I've been stressing that the high plains has been blessed with above normal precipitation - and in some areas excessively for multiple years.  If history was to repeat itself, the pendulum would definitely swing the other way. Unfortunately, I think that has started.  There are now strong signals that dryness will accelerate.  Here is the latest drought map (caution - it's ugly)...

Here is the precipitation map for the past 14 days....

Here is the percent of normal for May (very ugly for the high plains)…

The drought area that developed last fall did see some precipitation this past several weeks but not nearly enough or widespread enough to help much.

Now with hot and windy conditions, it will only get worse.  Will there be some help soon?  Unfortunately, it doesn't look like it.  Here is the satellite image from this evening...

That is not a very typical winds aloft configuration for late May.  One thing of note is the convection (thunderstorms) across Mexico.  I would hesitate to call that the birth of this years North American Monsoon, but it's something to watch.  Another interesting area is the large high pressure center northeast of Hawaii!  Could this be tied to what is now happening with Pacific Equatorial waters?  They have cooled significantly during the past several months.  Here is the latest 7 day average (notice the below normal waters now)….

The prediction is for a La Nina to develop this fall or winter.  Tied with water temperatures cooling down significantly across the north Atlantic could very well contribute to an expanding drought.  But wait!  Remember I said that the pattern that developed last fall had quite a few active systems? Yes, but here is the problem.  We are now in the Summer season.  Weather systems shift north (typically).  So, the active pattern would benefit the northern plains at least, maybe as far south as I-70 in Kansas.
Well then.  Does that mean that the high plains of Kansas will be dry until infinity?  No, I still insist that there will be several opportunities for widespread thunderstorms.  I'm just afraid that those opportunities will be fewer as things have shifted north.  IF during the opportune times that other processes are going on (like the warm layer aloft being too strong, or for what ever reason surface moisture is lacking, etc), then the drought will get worse and may start to expand east, despite some rainfall.

Here is my hope.  Back in one of the blogs I did in April (22nd), I mentioned June 18-19 as a curiously and potentially BIG period.  Could it be for the high plains?  There are hints by some longer range computer models that the last half with odds favoring above  normal rainfall.  I'm not buying in on that just yet.   It's not out of the range of possibilities that as the latter part of June arrives, that we get into a northwest flow aloft pattern.  That could yield what are called MCS's (Mesoscale Convective Systems) that are typically good rainfall producers - but unfortunately often bring a lot of wind.  If we don't get those, then it's going to get really bad.

Lastly, here is the outlook from the Weather Prediction Center through the end of next weekend.  Ugh.

With a lot on my plate (personal obligations) - I may not get another post done until ~ June 10 (the earliest would be the 8th).

Thursday, May 14, 2020

Update - May 14, 2020

After a "cold" period during this past week, it looks as if the weather will be warming up significantly.  BUT, that doesn't mean there won't be a few "cool" days mixed in during the next few weeks.  Soil temperatures this past week certainly took a hit.  Here is a map of 4" soil temperatures as of 215 PM this Thursday afternoon....

For mid-May, that is pretty cold don't you think?

For a while now I've been expecting an up-tick in weather activity from the 10th through 28th, specifically.  Since the last post I did on the 6th (you can read that post by clicking here), there were several systems bringing precipitation and generous amounts.  However, the growing drought area largely missed out.  This has been a concern of mine lately.  I sure have an uneasy feeling as we get deeper into the growing season.  Here is the map of rainfall (and actually snow in north central Kansas) for the past 7 days....

Eastern Kansas continues to be targeted with a lot of rain!  And the west?  Mostly missing out.  Will this continue through the 28th?

Again, I've expected this increase in activity for this period of 10th-28th that we've been in.  I would highly surprised is the drought area misses again, and again for this period.  Will it be enough to jump out of drought conditions.  I don't think so, at least through the rest of this month.  Here is the expected precipitation through next Thursday (from the Weather Prediction Center)….

With luck, that dry area will get quite a bit through the end of the Month.  But, I this point I wouldn't expect overly heavy rains.  I'm also concerned that other parts of the high plains may be on the edge of the elevated mixed layer (the warm air aloft or capping inversion that prevents widespread precipitation).

I'll try and update early next week....

Wednesday, May 6, 2020

Update - May 6, 2020

I'm starting this post by reviewing recent outlooks.  As you may recall in the post I did on April 14 I mentioned a possible light freeze or frost between May 1 and May 6 across the high plains.  I put the odds at rather small - but at that point there were absolutely no computer models hinting at much more cold for the remainder of the spring.  And, many forecasters said we were done with the cold.  In the post I did on April 22 I refined that cold outlook to May 5-6 (and the long range computer models STILL did no indicate any cold).  The cold arrived right on schedule!  Here is a map (at least for Kansas) of minimum temperatures ending May 5.

Here is a map of lows this morning (May 6).

Unfortunately there looks to be one more cold period at the end of this week.  Frost or a light freeze seems pretty certain either Friday morning or Saturday morning, or both.

In that last post, I also said that the May 5-6 period would probably be the next chance for widespread precipitation and probably severe thunderstorms.  Well both occurred, but only across the northern part of the high plains and on into eastern Kansas and Oklahoma.  That in itself is a little discouraging going forward and I'll explain later in this post.  Here is a map of severe weather reports for 05/04 ending 05/05...

So I feel pretty good that I was able to time the cold but why was the precipitation and severe weather displaced?  For early May there is typically a rich source of gulf moisture.  But because of frequent strong cold fronts this spring, the deeper moisture has often swept all the way through Texas and into the Gulf of Mexico.  So, because the lower atmosphere moisture has been less than normal for the high plains in advance of weather systems, the elevated mixed layer (capping inversion) has been strong enough to displace thunderstorms north and east of the majority of the high plains.  Will that continue?  To a point, probably but as we get deeper into May I think things should turn around.

In the previous outlooks I mentioned May 10-28 as being particular active.  I still believe that will be the case. Hopefully the majority of the active period will be wetter in lieu of severe weather but I'm pretty confident that severe weather episodes will ramp up.  Still - I have this uneasy feeling that  much of the high plains may be on the edge of the widespread rains.  It's just a feeling.  I'm still counting on much more rainfall.  Do you remember last year?  It was really dry until late April and then the faucet was turned on.  So far, that may repeat for a period this month.  But if it doesn't happen during this month, we may be in trouble.

Back to previous posts and outlooks.  Earlier in the winter, I was pretty confident that April would be cooler than normal and wetter.  The temperature outlook wasn't too bad.  But the precipitation outlook was trash!  There were systems but they were too fast and there wasn't enough boundary layer moisture in most cases.  Here is the percent of normal for April....

As a result, the drought has begun to expand once again across the high plains. There is that uneasy feeling again.  Here is the map of precipitation that fell during the previous 14 days ending this Wednesday morning (May 6)...

At least the northern part of the high plains did well.

And with that continued lack of precipitation across much of the high plains....the drought map.

So for that period of May 10-28...

To start, there should be several opportunities next week.  But before then, a weak disturbance moving southeast from the northwest U.S. (the red X on the satellite image below) will ignite widespread showers and thunderstorms this Wednesday night but unfortunately will largely miss the high plains again!

All indications from the Jetstream configuration should benefit at least part of the high plains next week.  One indication is the tropical connection.  That is indicated by the green arrows on the satellite image (bottom left stretching up into the Texas and Oklahoma panhandles).   That is likely tied to a rather robust (for May) MJO that continues propagating through the Maritime Continents.

Here is the outlook from the Weather Prediction Center through next Wednesday.

I'll do my best to update early next week.