Tuesday, August 29, 2017

Update - 08/29/17

What has happened to the pattern?  Well, it's now late enough in the summer that the upper atmospheric wind currents have reached their lowest average magnitudes (averaged across the northern hemisphere).  The general pattern that developed last fall is falling apart and won't start reorganizing for another 4 to 6 weeks.  I really hope that what we have now persists for that long (i.e., limited rainfall through September).

Since the last post on the 17th (read it by clicking here), the following is the accumulated rainfall:

That is quite a range of totals across the high plains (and especially eastern Kansas and western Missouri).

Here is the latest satellite image:

The North American Monsoon is GONE!  There continues to be scattered late afternoon high terrain showers and storms, only because of the residual moisture.  But the flow from the deep tropics into the west has ceased.  It could come back briefly before the end of September.  Also, the upper ridge across the Rockies is about as strong and robust as it has been all summer.  The resultant flow aloft across the high plains is north to south.  Surface moisture has dried out considerably.  This is partly due to "Harvey" that has pounded Texas and Louisiana. Usually a system in that area of the Gulf states plus the presence of a big upper ridge across the west is detrimental to the high plains receiving any rain.  Since the remnants of Harvey are slow moving, I don't see much hope for improvement in rain chances for at least a week (or more).  So, those areas that have really dried out lately will suffer.

Here is the outlook from the Weather Prediction Center:

BTW, next week or maybe even this Friday I will post about the summer rainfall for the high plains.  It's going to show a remarkable difference across short distances.  More on that later.

Finally, a look at the latest US Drought Monitor.  Some areas have improved, some have gotten drier.

I'll be discussing the fall outlook (and into winter) sometime in September.  I have a week long conference coming up in a couple of weeks and some other issues that need attention, so I'm not sure when I can get to that.  Stay tuned.

Thursday, August 17, 2017

Quick update - 08/17/17

In the post I did on Monday the 14th (read it by clicking here) I discussed the notion that the high plains was going to have an early fall - others ideas, not mine.   More on that towards the end of the post.

First, even though there was "some" rain across the western corn belt, drought conditions have worsened in the past week. Here is the latest available:

There was improvement across TX and OK at least.

For the next week (through August 24) the Weather Prediction Center is expecting some improvement across the corn belt - or at least some rain and with a return of the North American Monsoon (note the precip from Mexico into Colorado).

Back to the "early fall".  I've talked to several folks that are under the assumption that since it's been relatively cool and wet across much of the high plains since the last week of July, that an early fall was in the offing.  I'm assuming they mean we'll have an early freeze.

As I've stated numerous times in this blog, the pattern that produces the spring and summer weather, will change completely during the fall.  Having said that, I wanted to look at some numbers. 

The dramatic cool-down began on July 27 for the high plains.  For "most" of the area, it has been relatively cool and wet since then.   For Dodge City, the average temperature from July 27 through August 17 was about 4 1/2 degrees below normal. Going back since 1875 and looking at that exact period, this year ranks as the 18th coolest.   I took the top 15 coolest periods (again July 27 through August 17) for Dodge City and then looked at when the first freeze (32 degrees) occurred.   The result? On average, the first freezing temperature occurred 7.6 days after the 1981-2010 climatological average.  Only 3 of those years had an "early" freeze, and October 9 was the earliest date.  The first 28 degree temperature (killing freeze) occurred on average 2.7 degrees later than normal.  So what this says, is that based solely on climatology and with a similar cool late July and early August, there most likely will NOT be an early freeze.  Again, the pattern starts to change during the fall so at this point it's impossible to forecast.  Just a guess based on history. 

Here is the graph of those numbers.

Monday, August 14, 2017

Update - 08/14/17

Catching my breath, I can at least briefly post. 

The North American Monsoon (partly responsible for the high plains wetness) has abated, at least temporarily.  More on that below.  First...

Over the past 14 days, there have been incredible amounts of rainfall (August standards) for many locations across the high plains.  BUT, there continues to be those unfortunate ones that keep missing out.  One area is from near Dodge City to Concordia.  You can see that during the past 14 days, there are those heavy rainfall amounts but also the areas that have missed out.  Click on the map for a large (very large) image:

Unfortunately, there has also been a rash of very severe thunderstorms.  The hail and wind across the I-70 corridor on Thursday and also across Barber county on Wednesday was particularity bad.  Supercells (that produced the severe weather) of this magnitude are not unheard of for early August, but relatively rare.

Because of those that have missed out, moderate drought conditions have developed across the central third of Kansas and down into Oklahoma.  The western corn belt and into much of Iowa is getting progressively drier too, although there were some big rains over the weekend at some locations. Here is the latest drought monitor (as of August 8)

Looking at the latest satellite image...

Most notably was an anomalously strong upper level system across the western U.S..  The jet stream associated with this system was dipping pretty sharply south!  As this system moves out int the plains later in the week, there should be another a pretty big warmup for the northern plains followed by a cool down.  For the high plains, the result will be a boundary that will be part of the equation that will bring additional chances for thunderstorms.  This time it looks like areas farther east will be targeted, hopefully helping a bit with the moderate drought area.  Here is the latest thinking from the Weather Prediction Center....

I'm not sure if the NA Monsoon will return as strong as it has been during the summer, but it may not matter too much since the grounds are relatively wet and green across much of the high plains.  We'll see, but I would suspect that things will start drying out as September approaches.  You might know what that means.  Just like last year, take advantage of early top moisture for fall planting (for those that have benefited this summer anyway).

I've heard lately from a "lot" of people that because it's been wet and considerably cooler than normal during the past 3 weeks that we're going to have an early fall.  I'm taking that an early freeze would be expected - at least that's what they are saying. 

However, summer weather patterns usually have very little to do with the weather during the following fall (and especially into the winter).  Having said that, I did a really quick glance (since 1875) of late summers (late July into mid August) that were wet and "cold" at Dodge City and found that a very high percentage of those years actually had normal to late first freezes.  I'll do a little more digging into the past data and post here, maybe by Thursday (17th).