The US Northwest feels the heat

Aside from a few locations in mid-latitudes, July and August are the warmest months of the year. However, the northwestern US experienced extraordinary warmth over the past 6-8 weeks with most locations 2-3 degrees C (3-5 F) above normal adding to the crescendo of the hottest time of the year.

This has occurred in contrast to much of the eastern 2/3rd of the US that has seen cooler than normal conditions due primarily to a perturbation in the midlatitude wave track that brought enhanced ridging (warmer air) over western North America and pushed the jet stream well north, while cooler air and a dip in the jet stream impacted the eastern US.

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Looking through a few stations across the northwestern portion of the inland Northwest the following have had their warmest Jul 1-Aug 19 on record (40+ years)

  • La Grande, OR
  • Pullman, WA
  • Spokane, WA
  • Walla Walla, WA
  • Lewiston, ID

Likewise, many temperature records have also been seen across the Willamette Valley and southwestern Washington state as reported by NWS Portland and the Oregonian.

A sampling of some of the notable records by numbers:

  • 19: Number of consecutive days that Spokane Washington had overnight low temperatures of 60F+ (Jul 2-20, 2014) Interesting aside is that second longest streak since station moved to its current location in 1942 was 12 days, set from Jul 26-Aug 7 2014.
  • 7: Number of consecutive days that Wenatchee had overnight low temperature of 70F+ (Jul 13-19, 2014).
  • 13: Number of days in July with triple digit temperatures for Lewiston, Idaho.
  • 99.1: Average high temperature of the warmest 14-consecutive days on record at Moses Lake (July 6-19 2014, tied with late July 1998).
  • 79: All-time warmest overnight low temperature on record for Wenatchee, July 14th.
  • 256,108: Estimated acres burned by Cartlon Complex fire as of Aug 20th, most of which burned over a 5-day period (Jul 16-20th) along the easternmost extent of the Okanogan National Forest in north central Washington. The Cartlon Complex is the largest fire in Washington state per the observed record (100+ years) and has destroyed more than 300 homes.  A lightning bust on July 14th was the culprit for the fire as well as several other across the region. Lightning ignition combined with very receptive dry-fuels led to the right combination for large fire growth.

Reported impacts

  • Heat stress compounding drought stress on winter wheat yields in the central Columbia Basin, reported by AP.  The ongoing drought has received the most attention in California, but continues to have significant impacts in Oregon, southern Idaho and the western Columbia Basin in the lee of the Cascades. Since much of the dryland farming of wheat occurs, by definition w/o irrigation, the lack of precipitation over the past 10 months likely has resulted in moisture limitations. Heat stress was also reported to have impacted potato and onion crops in southwestern Idaho in July. Expect to pay more for that onion potato roll, if that’s your thing.

  • Smoke filled skies, again. The fire complexes burning along the east slopes of the Cascades and general prevailing westerly flow allowed for smoke to infiltrate the Spokane metro areas and regions from Lewiston, ID to Missoula, MT. The fires have also displaced wildlife in the region (largest heard of Mule deer in WA state have their winter range in areas that burned) leaving them to venture into agricultural lands.

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For those interested, I put together a webpage that provides maps of the National Fire Danger Rating System updated in near-real time http://nimbus.cos.uidaho.edu/NFDRS/

The reported lack of wildfire this year covered by various outlets with less than half the burned area in 2014 vs. the previous 10-year average may seem to contradict the active fire season in the NW. The NW and British Columbia have seen more than twice the amount of burned area so far in 2014 than in the previous 10-years thus reflecting a regional signature. US wide numbers are heavily influenced by whether Alaska and the southern plains have big fire years (in 2014 both had minimal fire). There has also been a lack of big rangeland fires this year in Nevada and Utah that can contribute significantly to US wide burned area.  The lack of big rangeland fires in these regions is possibly due to sub-par precipitation the past couple years have limited fuel buildup.