Review of Summer 2023

Now that the calendar has turned to September, it's time to take a look back and assess the summer.  First, we'll start with temperatures.  For the June-August period (also known as meteorological summer), temperatures in the Northwest were actually Much Above normal.  This kinda surprised me a bit, because it didn't really seem like a "hot" summer (we did have a few triple-digit days in August).  Elsewhere in the lower 48, parts of New Mexico, south Texas, Louisiana, Mississippi and Florida had their hottest summer on record (going back to 1895).  You may recall that Arizona was also extremely hot in July.  But their June was actually cooler than normal, so that helped to balance out the average.


So how did the folks at the Climate Prediction Center do with their summer outlook?  Here was what they were saying back in May for the Jun-Aug outlook.  Overall, they had the right idea, that the biggest anomalies would be found in New Mexico, stretching across the Gulf Coast states.  Their hot summer forecast for the East Coast didn't quite pan out, but the warmth in the Northwest and cool in the interior East worked at as well.  


For precipitation, the anomaly chart was rather surprising.  Some of the largest anomalies were actually in the West for a change.  For southern California and Nevada, this was largely due to one event:  remnants of Hurricane Hilary.  But the wet anomalies for Idaho, Wyoming and southern Montana also factored in other rainy events.  In the Northwest, things were on the dry side overall, but actually near normal for northeast Washington.  There were multiple rain events in August, and while they seemed rather strange and wet, they actually resulted in just normal rainfall for the summer average.  Perhaps we've become accustomed to dry summers and forgot what normal is.




Precipitation outlooks are extremely difficult to get correct.  So they usually get more of a pass in verification.  A couple of things CPC got right: a weak Southwest Monsoon season (dry in AZ and NM) and dry in the Northwest.  We can't really fault CPC for not predicting the remnants of a hurricane 3 months in advance.  The Above Normal area in the interior East didn't really pan out well.



Looking a bit closer at the Inland Northwest, here's some numbers from a few locations.

Deer Park Airport

  • Number of 80+F days: 95 (normal is 66)
  • Number of 90+F days: 30 (normal is 22)
  • Number of 100+F days: 3 (normal is 2)
  • Number of 60+F nights: 2 (normal is 3)
  • Total June-August Rainfall: 3.19"  (normal is 2.95")

Spokane Airport

  • Number of 80+F days: 89 (normal is 67)
  • Number of 90+F days: 28 (normal is 22)
  • Number of 100+F days: 2 (normal is 1)
  • Number of 60+F nights: 47 (normal is 25)
  • Total June-August Rainfall: 1.96" (normal is 2.13")

Colville

  • Number of 80+F days: 100 (normal is 80)
  • Number of 90+F days: 41 (normal is 36)
  • Number of 100+F days: 3 (normal is 5)
  • Number of 60+F nights: 9 (normal is 7)
  • Total June-August Rainfall: 3.38" (normal is 3.25")





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