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Idaho all-time record high...a short analysis


IbrChris

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The Idaho state record high of 118 at Orofino (1,027') on 7/28/1934 has seemed suspect to me in the past. In an attempt to determine the veracity I utilized an ad hoc event analysis for the late July 1934 heatwave.

My main questions:

  • Does the reading make sense given the topography (elevation, proximity to large bodies of water, continentality, aridity, etc)?
  • Does the reading make sense when compared with other local observations with similar topographical traits?

Without further adieu let's examine the topographical traits of some nearby stations.

Lapwai (891') - about 20 miles downstream from Orofino and also situated along the Clearwater in a narrow valley.

Kooskia (1,259') - 25 miles upstream from Orofino and also situated along the Clearwater in a canyon.
 

For comparison Lewiston (757') at the confluence of the Snake and Clearwater rivers in a broad valley.

 

All four are COOP stations...with a COOP station the high temperature depends on the time of day the observer reads the max/min thermometer (which is commonly during the early evening hours...5 or 6 pm local time was common). If the observations were made prior to the high temperature of the day, or right at it, the next-day's high temperature may be reflective of the previous day's high rather than the current day's high. Keep that in mind when observing highs that seemingly occurred on the same day yet are shown one day apart on the COOP obs.

 

It is pretty obvious the above scenario occurred at Orofino...the high on 7/27 was listed as 117 and the high on 7/28 was listed as 118...there weren't two separate days of 117+, what happened was the observer recorded the high for 7/27 which was 117 at the time he recorded it, then he reset the max/min thermometer and checked it again the next day which showed a 118 because the high for the day prior occurred after the observation was taken that day. I believe the Orofino 118 degree reading actually occurred on 7/27 rather than 7/28.

Nearby readings on 7/27 include:

116 at Lapwai
116 at Kooskia
114 at Lewiston
113 at Pete King R.S. (1,550')

Whether a station is located in a canyon or in an open valley/plain does reflect in terms of the maximum attainable temperature under identical atmospheric conditions. In a canyon you have a greater percentage of heated land-surface near the station which can produce higher temperatures on the canyon floor than would be encountered in a broad valley at the same elevation. I believe this "canyon" heating effect is the main factor allowing for Lapwai (and especially Orofino and Kooskia) to get hotter than would be expected given the slightly higher elevations versus Lewiston. All four locations are semi-arid with similar vegetation.

Lewiston actually managed to hit 117 in the pre-airport era on 7/27/1939. Slate Creek (in the Salmon River Canyon) at 1,566' hit 117 on 7/13/2002. A similar effect allows for some spots along the lower portion of the John Day River in eastern Oregon to reach the 115-116 mark during strong heatwaves (e.g. Monument, Dayville)

In conclusion I think the 118 reading is plausible at Orofino, and I feel comfortable listing it as the state record. It's not a "lone wolf" hot reading that sticks out well above other heat records in the region at locations with similar topography and elevation.

Comments are welcome, as always.

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The Pacific Northwest: Where storms go to die.

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Its interesting that you bring this up. I was in Pocatello, ID for much of this year (1/11/16 thru 10/1/16) for work. I payed as much attention to the weather as I could. Allot of people were saying how hot the summers are in Pocatello, being that it is situated in a high desert. They threw numbers out there like 120 degrees, 118 etc. I called BS instantly. I never did look up weather records to determine if they were indeed full of it or not. The highest temp this summer I believe was 96....

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In conclusion I think the 118 reading is plausible at Orofino, and I feel comfortable listing it as the state record. It's not a "lone wolf" hot reading that sticks out well above other heat records in the region at locations with similar topography and elevation.

 

 

Also interesting, Orofino reached 116F on August 4 1961.   It can definitely get hot there.  

 

Its interesting that you bring this up. I was in Pocatello, ID for much of this year (1/11/16 thru 10/1/16) for work. I payed as much attention to the weather as I could. Allot of people were saying how hot the summers are in Pocatello, being that it is situated in a high desert. They threw numbers out there like 120 degrees, 118 etc. I called BS instantly. I never did look up weather records to determine if they were indeed full of it or not. The highest temp this summer I believe was 96....

 

 
Yes, they were definitely full of it.   Pocatello does occasionally have temperatures of 100F or more, but it has never gotten warmer than 104F at the airport and 106F at another station well outside town. 
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Pretty crazy that some of those 1930s heat records still stand.

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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Good stuff. I was always a little wary of Orofino's record, simply because other heat waves (especially 1928, 1939, and 1961) seemed to be more likely candidates to set the ID state record. 

I spent several hours today putting together a temperature records narrative for Idaho similar to your write-up of Oregon records. Feel free to utilize it, and feedback including corrections is always welcome. That effort led to a more detailed examination of the all-time Idaho record high at Orofino.

 

The work on the narrative led me to revise the records listed in my spreadsheet database on a few occasions...definitely was worth the time IMO (and it was a pretty quiet day at work).

 

Orofino did manage 117 in the Aug 1961 heatwave.

The Pacific Northwest: Where storms go to die.

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Its interesting that you bring this up. I was in Pocatello, ID for much of this year (1/11/16 thru 10/1/16) for work. I payed as much attention to the weather as I could. Allot of people were saying how hot the summers are in Pocatello, being that it is situated in a high desert. They threw numbers out there like 120 degrees, 118 etc. I called BS instantly. I never did look up weather records to determine if they were indeed full of it or not. The highest temp this summer I believe was 96....

My folks live between Rexburg and Idaho Falls, and I can attest it doesn't get overly hot there in summer. Mid-90s are the warmest days in a typical summer with occasional upper-90s. 100-102 can occur but is quite rare at least north of about Blackfoot. Pocatello seems to reach 100 most years at the airport. On the other hand Boise gets pretty hot.

 

My folks don't even have window AC and they get along fine. Probably could use it on a handful of summer evenings but usually it cools off pretty quick after sunset.

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The Pacific Northwest: Where storms go to die.

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My folks live between Rexburg and Idaho Falls, and I can attest it doesn't get overly hot there in summer. Mid-90s are the warmest days in a typical summer with occasional upper-90s. 100-102 can occur but is quite rare at least north of about Blackfoot. Pocatello seems to reach 100 most years at the airport. On the other hand Boise gets pretty hot.

 

My folks don't even have window AC and they get along fine. Probably could use it on a handful of summer evenings but usually it cools off pretty quick after sunset.

That is one thing I did notice real quick around the end of May - beginning of June.... massive radiational cooling. I assume the elevation has just as much to do with it as the clear skies at night. 

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That is one thing I did notice real quick around the end of May - beginning of June.... massive radiational cooling. I assume the elevation has just as much to do with it as the clear skies at night. 

Yes the only warm nights occur when there's either good mixing with S-SE winds or convective debris cloudiness (like during SW Monsoon flow patterns).

The Pacific Northwest: Where storms go to die.

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