This Day in History!
Today marks the 30th anniversary of the event knowns as "Firestorm" in the Spokane Area. This event was characterized by a dry spell that occurred from late August through early October. The fall rains were late to arrive with fuels crispy dry and able to carry fire very easily. The event itself was driven by a strong cold front that produced extreme southwest winds with numerous ignitions from downed powerlines. Multiple fires broke out that quickly overwhelmed initial attack as strong winds fanned flames all across the Spokane Area. In this blog, we will re-visit Firestorm: news articles chronicling the event, the antecedent conditions, and of course the meteorology.
"Northern Spokane County like war zone"
Here is a portion of an article courtesy of the Spokesman Review detailing the conditions that day.
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| Article courtesy of Spokesman Review |
Below are a couple maps summarizing the fires across Northeast Washington and North Idaho, followed by a zoomed in look at the Spokane area.
A summary of various newspaper articles from that day showed
- 114 homes destroyed
- 2 fatalities
- 50,000 acres burned
- 80 fires
Lets shift gears and talk about conditions leading up to the event, beginning with total precipitation leading up to the summer of 1991. Below is a chart of precipitation accumulations at the Spokane International Airport for the water year. Each water year begins on the first of October. The month of October is when we will see mid-latitude storm systems move across the United States and is a good starting point for determining precipitation accumulations over an annual cycle.
The brown curve represents the average precipitation accumulation for the water year in Spokane and the green curve is the actual precipitation accumulation that fell from October 1st, 1990 through the day of Firestorm. Taking a quick glance, it's evident that precipitation accumulations followed the normal curve very closely; however, taking a closer look, it's also evident that a dry spell set up from August into the first half of October. Zooming into this period of the precipitation climate record (black rectangle above) and we see this:
July and August are typically our driest months of the year. The average, or normal, precipitation curve shows this with less than an inch of precipitation usually for this summer period. Then this curve starts to take more of an upward turn around mid September into October as weather systems off of the Pacific Ocean begin to usher in precipitation and shift out of fire season. It's clear to see zooming into this period that this precipitation was delayed. At the time, August through October of 1991 was the driest on record with only 0.18" recorded at Spokane International Airport -- 1.66" below normal!
How about the winds on the event? The next series of graphics are surface analysis charts showing mean sea level pressure (MSLP) through the event starting from the early morning hours on October 16th, 1991 into the afternoon. Keep in mind that the winds peaked during the late morning hours.
At 2:00 AM PDT
At 5:00 AM PDT
The storm intensified through the day, dropping from 994mb (29.35") at 2 am PDT to 984mb (29.06") at 2 PM PDT. The storm produced the strongest winds in the late morning when the low was in close proximity to Eastern Washington and North Idaho. Here are the observations from Spokane International Airport during the event.
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| Spokane International Airport observations for October 16th, 1991 from 7 AM to 7 PM PDT |
Note the wind/wind gust columns with a peak gust of 62 MPH. Also note the visibility and remarks where smoke and dust reduced visibility to as low as a quarter mile!
Where were you 30 years ago today? If you lived in Eastern Washington and north Idaho at the time, you probably still have memories of that day. Of course there have been many more Firestorms since 1991 (Carlton Complex, Okanogan Complex, Cold Springs/Pearl Hill, etc), but today we focus on what happened on October 16th, 1991.
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