Thursday, September 6, 2012

The Heat of Summer

The National Weather Service reports that this August was the hottest in the records at the Salt Lake City International Airport, and this summer (June–August) was the second hottest.  We obliterated the previous August record (1994) by 0.9ºF, while we just missed the summer record (2007) by only 0.1ºF.

1994 is now the third warmest year on record, although I think it carries on as the summer with the most 100 degree days (21).  This year we had 11.

The heat was associated with an upper-level ridge that setup over the central United States and dominated the weather for most of the summer, as shown in the mean and anomaly 500-mb geopotential height analyses below.

In August, this ridge was located a bit west of its mean position for the summer, which contributed to the anomalously high temperatures.

Note also that the ridge had a positive negative tilt, meaning the ridge axis was aligned from southeast to northwest.  This pattern helped keep monsoon moisture from penetrating into northern Utah.  

This was an exceptionally warm summer by historical standards, but we will see more like it in the coming decades.  


  1. I am ready for some cooler weather. It's looking cooler for next week which is promising.

  2. Disclaimer....I have posted before, am not a scientist but got a BS in Geoscience (included Meteorology)so I am "tuned" to weather things and weather is my hobby. I have been noticing now for about 5 years this "stuck", and I mean really stuck, type of pattern being the most significant synoptic thing that is happening to the weather in the mid latitudes. This blog post points this out. Last winter was the same, that ridge off the west coast that just would not move. My recollection of the past was winters that typically had periods of "progressive" storminess, fast moving west to east kind of events, and the occassional 1-2 week "stuck" kind of patterns, fortunately for us Utah powder lovers both pattern types tended to hit the Wasatch! However in the past two years, we have kind of gotten the "stuck" thing happening leaving us in a feast or famine mode. Now the Summer in Utah exhibits the same pattern. I live in Virginia and can tell you that the weather pattern feels very much the same. Our summers are almost always "stuck" as a result of the Bermuda high so we have not seen a huge difference here in the summers since this kind of pattern change.

    Has any study been done on the reason for this type of change? I have heard that the delta between warming in northern latitudes (>60) vs midlatitudes warming leads to a higher than normal latitudinal jet stream, but nothing seems to speak to this "stuck" thing.

    Hoping for some thoughts from you!


    1. Pem:

      Start here:

      The authors argue that arctic amplification leads to more persistent mid latitude weather due to weaker zonal flow and increased wave amplitude.


    2. Perfect, thanks Jim!!..Pem