Friday, May 28, 2021

More Wet May Weather in Store

 In the previous post I did on the 19th (click here) I discussed another period of precipitation starting as early as the 21st but with increasing likelihood for severe weather.  Unfortunately the severe part became a reality.  As far as rainfall, here is what fell this past 7 days ending this morning (28th)...

With the added precipitation during the past few weeks, there has been a dramatic change in the drought monitor.

Will this trend continue?  In the previous post I mentioned signals pointing to a wetter than average June.  Some of the signals have backed up a bit, but I'm still leaning for near or above normal rainfall for most locations.

For the near term, a cold high pressure system settling into the midwest will promote gulf moisture to return across west Texas and into the high plains.  A weak, but important disturbance aloft will intensify into the southwest U.S. and will help to produce several rounds of showers and thunderstorms over the weekend and into early next week.   The majority of the rainfall will likely be concentrated over the southern High Plains but with a fair amount into Kansas/Colorado. That developing system is denoted by the red X across the eastern Pacific with it's eventual track indicated by the red dotted line/arrow.

There may be a prolonged (3 to 5 days) break beginning mid-week. 

Here is an early look at how much rain "might" fall through late next week, with the majority falling through the 2nd of June.

More on the June and July outlook in the next post.

Wednesday, May 19, 2021

Relief For Most of The High Plains

Very thankfully there has been widespread precipitation during the past few weeks - well actually for much of May so far, without a lot of hail and wind.  In the previous update I did on April 30 (read it by clicking here) the title of that particular post was "Will it be a repeat of 2011?".  For several months I have seen hints of what happened in 2011 - there were actually quite a few similarities in the signal.  That had me concerned but if you had read that posting or go check out the April 30 entry, you will see the following important statement: Am I still concerned?  Yes, but actually just barely. I was finally starting to see signals pointing to an increase in precipitation, for at least May.  The biggest contributor to the possibility was a strong MJO (Madden Julian Oscillation) and subsequent phase space.  "IF" May ended up wet then I had hopes of mitigation to possible dryness for the majority of the growing season into summer.  More on that in a bit.

Another component to my thought process has been looking at the length of magnitude of cycling nature of the upper atmospheric flow across the northern hemisphere.  Both elements have seemed to work in favor of precipitation across the high plains (and associated cooler than normal temperatures).  Here is a look at what has fallen for this May through 7 AM this morning, May 19.

There has been very generous precipitation for most locations with actually too much rainfall in some areas.  Locations in west central Kansas have ALREADY reached the wettest May on record!  Wow!  And look at the area around Salina with over 10 inches so far!

What a change! Especially for the areas with greatest drought impacts!  The drought monitor map has been updated only through the 11th, so much of the latest rainfall has not been incorporated into the drought analyst.  I suspect big improvements on the next issuance.

Here is a look at the jetstream map from this morning (19th)...

The upper low (the red L) over Clayton, NM this morning has been slowly meandering this way for the past week and has contributed to much of the rainfall (and heavy snow in the southern Rockies).   The influence of that feature will be out of here by the end tomorrow (Thursday).  But, we're not necessarily done with the precipitation!

A deep upper trough (the start is the L near Washington State on the map above) will be in place across the western U.S. for the next 4-5 days or so.  This will promote warming temperatures (surface and aloft) across the high plains.  IF the upper level temperatures don't get too warm, then there will continue to be opportunities for rainfall.  However, the bad news is that that precipitation will come in the form of thunderstorms and there will likely be severe weather too.  The most likely time-frame will be early next week, although there could still be at least widely scattered activity starting this Friday the 21st.  Here is the outlook for precipitation through next Wednesday (from the Weather Prediction  Center)...

Finally, I'm seeing strong signals for above normal precipitation for June!  Confidence is increasing anyway.  IF June ends up wetter than normal, then the likelihood that July temperatures will be at or even slightly cooler than average is seemingly becoming a possibility.  More on that later.

I'll do my best to update by the end of next week.

And again, if you haven't had a chance to submit the very short survey....