Ag Weather Forum
Doug Webster DTN Senior Ag Meteorologist

Monday 08/25/14

Where Have the 90-Degree Days Gone?

Those of us who wait all winter for those lazy, hazy, hot days of summer have been disappointed this summer as the typical periods of hot, humid weather we normally see across a large portion of the central and eastern U.S. have been hard to find. Absent has been the subtropical ridge which we rely on to allow heat to build under the upper level dome of warm air.

Numerous recording sites from the Plains through the Midwest and into the East all are reporting very low numbers of 90-degree afternoon high temperatures so far this summer. In some cases the 90-degree mark has not been reached and time is starting to run out as summer fades into meteorological fall in just a week.

Hot weather has made an appearance across many portions of the central and southern Midwest and Plains during recent days but for many areas this is the first such "hot spell" of the summer and is not really anything to write home about. This burst of summer temperatures does not look like it will have staying power as some polar air gets back into the mix later this week across the northern half of the central and eastern U.S.

The reasons behind the cool summer are pretty much the same as the reason we saw the cold winter and spring. High latitude blocking has been a persistent feature across North America and through the Greenland region through most of the summer. Only during the past 5 days have we seen this blocking relax enough to allow the subtropical ridge to grow northward into the south-central U.S.

The Bermuda high has also been on vacation this summer and has tended to stay across the central Atlantic rather than poking west into the East Coast of the U.S. as it does many times during a normal summer. The lack of this "heat pump" has kept places like Boston, New York, and Washington D.C. with very few 90-degree afternoons.

More often than not we have seen polar air masses make their way southward into the Midwest and East bringing cooler, drier air. Some of these fronts have even made their way all the way into the southern U.S. bringing cooling to even our most southern states.

The Southwest has also seen "cool" weather during the past month with temperatures averaging as much as 2 to 4 degrees below normal so far during August. Phoenix, Arizona has seen 9 days during August when temperatures have failed to reach the century mark. Normal high temperatures are a few degrees over the 100-degree mark.

Current model products are telling us that summer may try to make a modest attempt to continue into early September with the mostly missing subtropical ridge expected to be more of a player in our weather across the central and eastern U.S. This might mean a few places may add a few more hot days into the tally before summer finally does fade away.

Doug Webster can be reached at doug.webster@dtn.com

Posted at 11:46AM CDT 08/25/14 by Doug Webster
Comments (6)
Must be you have not been outside much this week!The cool temps earlier this summer are probably our only saving grace,with very little rain since June.We will be shelling corn and running beans next month.
Posted by Raymond Simpkins at 10:13AM CDT 08/26/14
we are in mi. and no 90 this year , lots of rain and big crops comimg .
Posted by Arlen Meeuwsen at 3:52PM CDT 08/26/14
I just got back from a family vacation in McCall Idaho. I was led to believe the inter mountain west and west coast is where all the heat was positioned this Summer. We took a boat cruise on Payette Lake on Saturday afternoon and it was so cold at 2 pm that the boat crew dug out the blankets to keep as somewhat warm. So no heat out there. So where is it?
Posted by MARK & LEA NOWAK at 4:59PM CDT 08/26/14
What is causing the "High Latitude Blocking" ?
Posted by Darwin blank at 11:19PM CDT 08/26/14
We had a fairly "cool" July for western Kansas standards, but August has made up for that. Most of the month of August has been mid to upper 90's with several 100 degree days mixed in. August 2013 was much cooler than this year. We've also only had very spotty rains. Localized areas have seen several inches in an event and fields within in a few miles getting trace amounts. Thru July we had grand visions of finally seeing a good dryland sorghum crop after numerous years of drought, but that is fading fast. Although we had some rains this summer the High Plains region in general is still very dry in regards to profile moisture. I know I'm hoping for an El Nino to maybe bring some much needed moisture to this region.
Posted by Brad Niehues at 8:54AM CDT 08/27/14
OMG, it is global cooling!!! We better pass some sort of treaty or global agreement to address this situation right now.
Posted by Mr. Brandy at 11:50AM CDT 08/28/14
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