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Washington State Temperature Records by Month w/ a little analysis


IbrChris

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My aim here is to vet the unofficial record highs and lows for the state of Washington. By "vet" I mean examine the readings in the context of the event (utilizing data from surrounding stations) and the geography of the area surrounding the station. Erroneous readings are fairly common in the COOP data, however NCDC for a long time accepted the COOP values as legitimate. Many of the values accepted as records have turned out to be likely erroneous, commonly due to bad siting and overexposure. There are also human errors introduced by the observers as well. This is a cursory attempt to list the most credible records by month after an extensive review of the available data:

January

 

Record high: 74 at Darrington on 1/31/1940 and Mud Mtn Dam on 1/28/1940, both areas influenced by downslope warming. The former corroborated by a reading of 66 at Sedro Woolley and the latter by a 70 at Buckley the same day.

Record low: -42 at Deer Park on 1/20/1937 supported by -33 at Chewelah the same morning.

 

February

 

Record high: 78 at Glenoma on 2/28/1986. 73 at Centralia and 75 at Oakville on 2/27. 74 at Everett and Sedro Woolley on 2/28.

Record low: -40 at Deer Park on 2/9/1933. -38 at Chewelah and -36 at Newport the same morning.

 

March

 

Record high: 87 at Kennewick on 3/30/1911. 86 at Mottinger on 3/29. 85 at Kiona on 3/30. Oregon recorded its March record high a day later.

 

Record low: -25 at Stockdill Ranch (Okanogan Co.) on 3/4/1955. Numerous corroborating readings the same morning: -24 Chesaw, -19 Republic, -17 Conconully

April

Record high: 100 at Wahluke on 4/29/1926. 98 at Kiona and Mottinger on 4/28. 96 at Sunnyside on 4/29.

Record low: -7 at Lake Keechelus on 4/1/1936. A known cold wave, -1 at Bumping Lake on 4/3.

May

Record high: 107 at Dallesport (The Dalles Airport) on 5/30/1986. 107 at Arlington, OR on 5/30 and at The Dalles, OR on 5/31.

Record low: 10 at Paradise Mt Rainier on 5/19/1987. Camp Muir reached 2 on 5/5/2010 (automated sensor)

 

June

 

Record high: 114 at Hanford on 6/28/2015. Greatest June heatwave on record...113 at Chief Joseph Dam, 113 Lacrosse, 113 Walla Walla airport the same day.

Record low: 13 at Paradise Mt Rainier on 6/1/1933. Camp Muir reached 11 on 6/7/2012.

July

 

Record high: 118 at Wahluke on 7/24/1928. 114 at Kiona the same day. 113 at Omak the same day. 113 at Walla Walla on 7/26.

Record low: 20 at Paradise Mt Rainier on 7/23/1924. Camp Muir reached 18 on 7/3/2012.

 

August

Record high: 118 at Ice Harbor Dam on 8/5/1961. 116 Connell, 115 Ephrata airport, 115 Smyrna, 115 Wilson Creek on 8/4. 114 at Dayton and Othello on 8/5.

Record low: 20 at Cascade Tunnell on 8/19 and 8/20/1896. Few stations in 1896 so this reading is tough to corroborate, however Wenatchee fell to 35 on 8/10/1896.

 

September

Record high: 108 at Glenoma on 9/3/1988. 105 at Battle Ground the same day. 105 at Packwood on 9/2.

 

Record low: 11 at Mt Adams RS on 9/25/2000 (known to be a cool period) and at Newport on 9/25/1934. Glenwood hit 19 on 9/23/2000. West of the Cascades Olympia was 26 on 9/23/2000.

October

Record high: 99 at Glenoma on 10/2/1987. 97 Packwood, 96 Toledo, 95 Snoqualmie Falls on 10/1.

Record low: -5 at Bumping Lake and Republic, both on 10/31/1935. -2 at Odessa, -1 Chesaw, -1 Newport the same morning. Earliest measurable snow on record in Portland, OR on 10/30.

November

Record high: 83 at Kosmos (later inundated and relocated to Glenoma) on 11/2/1949. 78 at Startup the same day.

Record low: -29 at Ellensburg on 11/28/1896. -23 at Sunnyside and -22 at Moxee the same morning.

December

 

Record high: 74 at Sedro Woolley on 12/5/1939 and at Wahluke on 12/21/1933. Pomeroy hit 72 on 12/5/1939 and Lowden (near Walla Walla) reached 71 on 12/21/1933.

 

Record low: -48 at Mazama and Winthrop on 12/30/1968. -43 at Chesaw 4 NNW on 12/29. -38 at Republic on 12/30.

 

 

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Some pretty impressive numbers overall. I'll bet the -29 in November holds it's own with a good percentage of the other states. The all time low of -48 is as cold or colder than many states east of the Rockies.

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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Some pretty impressive numbers overall. I'll bet the -29 in November holds it's own with a good percentage of the other states. The all time low of -48 is as cold or colder than many states east of the Rockies.

Yes most states east of about 100 W longitude have colder March record lows than November record lows (and except in the Upper Midwest and Great Lakes they're warmer than WA). The WA value is fairly comparable to other western states in Nov: Oregon -32, Idaho -38, Montana -53, Utah -44, Wyoming -46, Colorado -41 and California -28.

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One thing that stands out is Glenoma is probably the hottest location west of the Cascades in Washington, at least in offshore flow scenarios. It makes sense when you look at the fairly straight E-W orientation of the middle Cowlitz River valley and the steep terrain on all sides as it approaches White Pass. Similarly the Skagit River Valley around Nehalem/Marblemount gets quite hot.

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Some other readings that may be of interest:

 

-Kennewick hit 74 on 1/10/1896, it was 70 in Connell

-Everett, Monroe, and Kosmos hit 72 on 1/31/1935

-West of the Cascades, January 1930 produced readings of -20 in Longview, -18 in Kelso and -13 in Castle Rock

-Startup hit 77 on 2/29/1968

-86 at Mottinger on 3/30/1923 (82 in downtown Portland)

-103 at Wahluke on 4/22/1934. This reading sticks out a bit, which is why I'm guessing Chris didn't include it in his summary. Some places did hit the mid 90's including readings of 95 at Hanford and Okanogan

-Republic hit 11 on 5/1/1954

-Lower Granite Dam has 111 on the books for 9/1/1967, although this was most likely the maximum on 8/31 

-Anatone, Newport, Chewelah, and Cle Elum all hit 12 degrees in September 1926 (various dates between the 23rd-26th)

-98 at Mottinger on 10/2/1943

-Whitman Mission hit 82 on 11/13/1999

-73 in Walla Walla on 12/12/1921, it was 70 in Kennewick

 

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Some other readings that may be of interest:

 

-Kennewick hit 74 on 1/10/1896, it was 70 in Connell

-Everett, Monroe, and Kosmos hit 72 on 1/31/1935

-West of the Cascades, January 1930 produced readings of -20 in Longview, -18 in Kelso and -13 in Castle Rock

-Startup hit 77 on 2/29/1968

-86 at Mottinger on 3/30/1923 (82 in downtown Portland)

-103 at Wahluke on 4/22/1934. This reading sticks out a bit, which is why I'm guessing Chris didn't include it in his summary. Some places did hit the mid 90's including readings of 95 at Hanford and Okanogan

-Republic hit 11 on 5/1/1954

-Lower Granite Dam has 111 on the books for 9/1/1967, although this was most likely the maximum on 8/31 

-Anatone, Newport, Chewelah, and Cle Elum all hit 12 degrees in September 1926 (various dates between the 23rd-26th)

-98 at Mottinger on 10/2/1943

-Whitman Mission hit 82 on 11/13/1999

-73 in Walla Walla on 12/12/1921, it was 70 in Kennewick

Yeah I noted most of these when I was researching the records I posted...the Wahluke reading was dismissed due to likely overexposure, in most events Wahluke and Hanford are within 3-4 degrees of each other (Wahluke generally warmer). A more accurate reading that day was probably 98-99 at Wahluke.

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Some other readings that may be of interest:

 

-Kennewick hit 74 on 1/10/1896, it was 70 in Connell

-Everett, Monroe, and Kosmos hit 72 on 1/31/1935

-West of the Cascades, January 1930 produced readings of -20 in Longview, -18 in Kelso and -13 in Castle Rock

-Startup hit 77 on 2/29/1968

-86 at Mottinger on 3/30/1923 (82 in downtown Portland)

-103 at Wahluke on 4/22/1934. This reading sticks out a bit, which is why I'm guessing Chris didn't include it in his summary. Some places did hit the mid 90's including readings of 95 at Hanford and Okanogan

-Republic hit 11 on 5/1/1954

-Lower Granite Dam has 111 on the books for 9/1/1967, although this was most likely the maximum on 8/31 

-Anatone, Newport, Chewelah, and Cle Elum all hit 12 degrees in September 1926 (various dates between the 23rd-26th)

-98 at Mottinger on 10/2/1943

-Whitman Mission hit 82 on 11/13/1999

-73 in Walla Walla on 12/12/1921, it was 70 in Kennewick

-20 on the West Side is ridiculous!

 

I'm guessing it was mostly due to extremely low dew points resulting from Columbia Gorge outflow for a long period of time in combination with snow cover. Many other parts of Western WA have been colder with other cold snaps than they were with 1930, but the duration on that one was extraordinary.

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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The Dec 1919 event (generally Dec 10-14) was probably the coldest west of the Cascades in the modern records...though it was most intense in the central Willamette Valley

Dec 12th

-24 McMinnville (coldest reading ever at a westside station below 1000')

-15 Forest Grove

-14 Corvallis

-11 Albany
-10 Miramonte Farm (Clackamas Co.)

Dec 13th

-22 McMinnville

-15 Albany
-15 Forest Grove
-14 Wallace Orchard (Polk Co.)
-11 Miramonte Farm (Clackamas Co.)

Salem made it down to -6 and Eugene -3 in this event.

The Dec 1919 event had some impressive lows in SW WA as well:

-16 Centralia
-15 Glenoma
-13 La Center
-10 Vancouver
-8 Oakville

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Its also interesting to note that the -41 degree reading @ Newport on 1/30/1950 came within 1 degree of the state record low, which at the time stood at -42 (at Deer Park on 1/20/1937). Its pretty remarkable that the previous WA state record was broken at three different locations in the December 1968 cold wave: -48 at Mazama, -48 at Winthrop, and -43 at Chesaw (as noted in the opening post of this thread). 

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The Dec 1919 event (generally Dec 10-14) was probably the coldest west of the Cascades in the modern records...though it was most intense in the central Willamette Valley

 

Dec 12th

 

-24 McMinnville (coldest reading ever at a westside station below 1000')

-15 Forest Grove

-14 Corvallis

-11 Albany

-10 Miramonte Farm (Clackamas Co.)

 

Dec 13th

 

-22 McMinnville

-15 Albany

-15 Forest Grove

-14 Wallace Orchard (Polk Co.)

-11 Miramonte Farm (Clackamas Co.)

 

Salem made it down to -6 and Eugene -3 in this event.

 

The Dec 1919 event had some impressive lows in SW WA as well:

 

-16 Centralia

-15 Glenoma

-13 La Center

-10 Vancouver

-8 Oakville

It was nothing really special in this area due to lack of snow. Many 20th century events beat it in the Seattle area. Dec 1924 was certainly better here among others.

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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Its also interesting to note that the -41 degree reading @ Newport on 1/30/1950 came within 1 degree of the state record low, which at the time stood at -42 (at Deer Park on 1/20/1937). Its pretty remarkable that the previous WA state record was broken at three different locations in the December 1968 cold wave: -48 at Mazama, -48 at Winthrop, and -43 at Chesaw (as noted in the opening post of this thread).

My first real weather related memory is of my dad thawing some pipes with a torch during that cold wave. I also have some brief memories of the snow in January 1969. Crazy winter!

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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-20 on the West Side is ridiculous!

 

I'm guessing it was mostly due to extremely low dew points resulting from Columbia Gorge outflow for a long period of time in combination with snow cover. Many other parts of Western WA have been colder with other cold snaps than they were with 1930, but the duration on that one was extraordinary.

 

Yeah, this was a very long lasting cold wave that was greatly abetted by snowcover. The original COOP forms show peak depths of 18" at Longview and 18.5" at Kelso. Longview averaged a minimum of 5.0F between the 9th and 25th that month. Crazy stuff.

 

http://www1.ncdc.noaa.gov/pub/orders/IPS/IPS-53F1E0BD-4D4A-4AD2-A55F-DC85098A0E4D.pdf

 

http://www1.ncdc.noaa.gov/pub/orders/IPS/IPS-2FD80360-784C-4589-886B-F4F3064219E7.pdf

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It was nothing really special in this area due to lack of snow. Many 20th century events beat it in the Seattle area. Dec 1924 was certainly better here among others.

It lacked snow, but it was still extremely impressive from a cold standpoint. UW had three consecutive highs in the teens and a low of 5 on the 12th.

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It lacked snow, but it was still extremely impressive from a cold standpoint. UW had three consecutive highs in the teens and a low of 5 on the 12th.

 

It was definitely an impressive cold wave in the Seattle area, despite the lack of snowfall. Puyallup hit -1 with essentially bare ground. Snowfall totaled 0.5" that month. 

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My first real weather related memory is of my dad thawing some pipes with a torch during that cold wave. I also have some brief memories of the snow in January 1969. Crazy winter!

 

That's awesome. My first weather related memory was the January 1987 cold wave in St. Petersburg, Russia. The official low was -31F in the city, which threatened the all-time record of -33F from January 1883. Our building had a hot water central heating system, which failed when the pipes burst. I remember my parents hanging blankets on the windows to keep the cold out. And we wore jackets indoors for a couple days.  :lol:

 

That was a major cold wave across Europe as well. 

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That's awesome. My first weather related memory was the January 1987 cold wave in St. Petersburg, Russia. The official low was -31F in the city, which threatened the all-time record of -33F from January 1883. Our building had a hot water central heating system, which failed when the pipes burst. I remember my parents hanging blankets on the windows to keep the cold out. And we wore jackets indoors for a couple days.  :lol:

 

That was a major cold wave across Europe as well. 

Wouldn't have guessed you were born outside the U.S. That sounds like a pretty miserable situation.

 

My first weather related memory was a pipe bursting in our garage during the Feb 1995 cold snap. 2nd earliest was looking down SW Martinazzi Avenue in Tualatin during the Feb '96 flood and seeing half of the town underwater.

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Wouldn't have guessed you were born outside the U.S. That sounds like a pretty miserable situation.

 

My first weather related memory was a pipe bursting in our garage during the Feb 1995 cold snap. 2nd earliest was looking down SW Martinazzi Avenue in Tualatin during the Feb '96 flood and seeing half of the town underwater.

 

My family came to the US in 1992. So I've had some time to learn English! 

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One thing interesting about the Washington cold snaps is a large number of the coldest ones have come in December (even early or in the middle of the month), including to the locations near the ocean.   November has had some impressive ones as well.

 

In fact, for much of western Washington, the average coldest day of the year is before the winter solstice.  

 

coldest-day-new.jpg

 

This is actually the exact opposite of what would be expected in a location next to the ocean.  I wonder why that is?  

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-Republic hit 11 on 5/1/1954

 

 

That cold snap was an impressive one since several locations in Washington and Oregon not only broke their May records, but they were colder than the April records as well.  Even the airports at Seattle and Portland tied or exceeded the April records.  

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One thing interesting about the Washington cold snaps is a large number of the coldest ones have come in December (even early or in the middle of the month), including to the locations near the ocean.   November has had some impressive ones as well.

 

In fact, for much of western Washington, the average coldest day of the year is before the winter solstice.  

 

coldest-day-new.jpg

 

This is actually the exact opposite of what would be expected in a location next to the ocean.  I wonder why that is?  

It's probably just a reflection of the fact that most of our big blasts have come early in the season in the last 35 years. The early peak is also helped by our inversion season peaking from late November to mid January, though on its own that doesn't explain why the coldest day of the year would occur before the solstice.

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It lacked snow, but it was still extremely impressive from a cold standpoint. UW had three consecutive highs in the teens and a low of 5 on the 12th.

Interesting. The city records weren't that cold.

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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It's probably just a reflection of the fact that most of our big blasts have come early in the season in the last 35 years. The early peak is also helped by our inversion season peaking from late November to mid January, though on its own that doesn't explain why the coldest day of the year would occur before the solstice.

The funny thing is our coldest day used to be around Jan 18. The last 30 years have been extremely front loaded. We just might be seeing that change...at least for this winter. This is why people are already freaking out about the way things are playing out this season. Much more reminiscent of old times being warm early on.

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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I think this will illustrate why I'm not thrilled about December 1919. A repeat of that month would really piss me off. :lol:

 

Landsburg numbers for 1919...granted there was NO snow on the ground so the numbers are impressive for that.

 

32-13

31-15

27-16

25-8

26-3

32-7

35-14

 

Now for Dec 1924 which had a one foot snowstorm going into the blast.

 

50-32

35-13

19-3

18-0

21-4

27-14

28-23

29-6

33-7

33-7

31-8

36-10

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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One thing interesting about the Washington cold snaps is a large number of the coldest ones have come in December (even early or in the middle of the month), including to the locations near the ocean.   November has had some impressive ones as well.

 

In fact, for much of western Washington, the average coldest day of the year is before the winter solstice.  

 

coldest-day-new.jpg

 

This is actually the exact opposite of what would be expected in a location next to the ocean.  I wonder why that is?  

Bonus points if you can figure out why the higher basins in WY are coldest in mid-late Jan vs the eastern plains in Dec. Same with CO.

The Pacific Northwest: Where storms go to die.

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Bonus points if you can figure out why the higher basins in WY are coldest in mid-late Jan vs the eastern plains in Dec. Same with CO.

 

 

For the higher basins, it is mostly because of snow cover.   The coldest nights in the higher elevation basins are usually on clear nights with a good snow cover.   In the high country, normally the snow cover in much better in late January than in December.    The Eastern Plains only see sporadic snow cover throughout the season.

 

Interestingly, the high mountains have more seasonal lag than the lower elevations, especially outside the valley floors, even in places where the snow often gets blown off.

 

In much of the Eastern Plains or other low elevation places in Colorado (below 6000 feet), April and October have almost the same average temperature.   If you go up to Climax (11,360 feet) or Berthoud Pass (11,315 feet) , April has an average temperature of somewhere between October and November.    If you go up to Pikes Peak (14,115 feet), April is almost as cold as November and May and October have almost the same average temperature.

 

The same is true in other mountain areas as well.    There is more seasonal lag.   In the Cascades, at Crater Lake, for example, April is almost as cold as November, which isn't true in the low land valleys to the east.

 

Of course places near the ocean should also experience seasonal lag since it takes longer to heat up large bodies of water than land that is far away from the ocean.   That's what makes the early season cold snaps on the West Coast interesting and unexpected.   Along the coast, October records "should" be colder than April records and March records "should" colder than November records.   Of course records do produce unexpected anomalies, but the coast line of the Pacific Northwest has had many early season cold spells, even in comparison to later in winter, rather than just a few unexpected anomalies.

 

Even though the above chart is only based on a 30 year period, it is still most unexpected for a coastal area.  

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For the higher basins, it is mostly because of snow cover.   The coldest nights in the higher elevation basins are usually on clear nights with a good snow cover.   In the high country, normally the snow cover in much better in late January than in December.    The Eastern Plains only see sporadic snow cover throughout the season.

 

Interestingly, the high mountains have more seasonal lag than the lower elevations, especially outside the valley floors, even in places where the snow often gets blown off.

 

In much of the Eastern Plains or other low elevation places in Colorado (below 6000 feet), April and October have almost the same average temperature.   If you go up to Climax (11,360 feet) or Berthoud Pass (11,315 feet) , April has an average temperature of somewhere between October and November.    If you go up to Pikes Peak (14,115 feet), April is almost as cold as November and May and October have almost the same average temperature.

 

The same is true in other mountain areas as well.    There is more seasonal lag.   In the Cascades, at Crater Lake, for example, April is almost as cold as November, which isn't true in the low land valleys to the east.

 

Of course places near the ocean should also experience seasonal lag since it takes longer to heat up large bodies of water than land that is far away from the ocean.   That's what makes the early season cold snaps on the West Coast interesting and unexpected.   Along the coast, October records "should" be colder than April records and March records "should" colder than November records.   Of course records do produce unexpected anomalies, but the coast line of the Pacific Northwest has had many early season cold spells, even in comparison to later in winter, rather than just a few unexpected anomalies.

 

Even though the above chart is only based on a 30 year period, it is still most unexpected for a coastal area.

Awesome post!

 

I think the whole thing with the Western Lowlands of the PNW being so disproportionately cold early in the season has a lot to do with it being more likely to see favorable 500mb blocking early in the season than late in the season...especially in the last 30 to 35 years. Decades ago we did see more significant late season cold snaps including a full on Arctic blast in mid March 1870. More recently there was an impressive event in very late March / early April 1936, but things like that have always been rare.

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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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For the higher basins, it is mostly because of snow cover.   The coldest nights in the higher elevation basins are usually on clear nights with a good snow cover.   In the high country, normally the snow cover in much better in late January than in December.    The Eastern Plains only see sporadic snow cover throughout the season.

 

Interestingly, the high mountains have more seasonal lag than the lower elevations, especially outside the valley floors, even in places where the snow often gets blown off.

 

In much of the Eastern Plains or other low elevation places in Colorado (below 6000 feet), April and October have almost the same average temperature.   If you go up to Climax (11,360 feet) or Berthoud Pass (11,315 feet) , April has an average temperature of somewhere between October and November.    If you go up to Pikes Peak (14,115 feet), April is almost as cold as November and May and October have almost the same average temperature.

 

The same is true in other mountain areas as well.    There is more seasonal lag.   In the Cascades, at Crater Lake, for example, April is almost as cold as November, which isn't true in the low land valleys to the east.

 

Of course places near the ocean should also experience seasonal lag since it takes longer to heat up large bodies of water than land that is far away from the ocean.   That's what makes the early season cold snaps on the West Coast interesting and unexpected.   Along the coast, October records "should" be colder than April records and March records "should" colder than November records.   Of course records do produce unexpected anomalies, but the coast line of the Pacific Northwest has had many early season cold spells, even in comparison to later in winter, rather than just a few unexpected anomalies.

 

Even though the above chart is only based on a 30 year period, it is still most unexpected for a coastal area.  

Yeah I agree with you...I also believe it's due to the typical development of the Great Basin high in Jan/Feb over the intermountain west which promotes clear, calm conditions and strengthening inversions in high elevation basins. Notice that SW Montana sees their coldest temps generally in mid-late December even though that area is mainly high elevation basins (like the Big Hole Basin). However, SW Montana tends to see a more active pattern throughout the winter than areas to the south and east.

 

Snowcover promotes inversions but if a progressive storm track remains over the region strong inversions are less likely to form. Most of these basins have snowcover from early-mid Nov to late March and the effect of snowcover on 2 meter temps is the same whether it's 1" or 30".

 

I've thought the early-season cold snaps on the west coast have a lot to do with the evolution of the Hudson Bay low (typical arctic polar vortex or PV)...early in the winter the PV is typically weaker allowing for eddies that can dive south to impact mid-latitudes. Later in the winter the PV is often more consolidated/stronger and centered generally between Southampton Island and Baffin Island. While this allows for cold air to funnel down east of the Rockies, the west coast is less likely to see cold temps as we need both a deeper arctic layer and enough dynamics to force the arctic air to move WSW across both the Rockies and the Cascades. This forcing is usually achieved with shortwaves accompanied by PV lobes/eddies which are less likely later in the winter when a stronger PV exists across NE Canada.

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The Pacific Northwest: Where storms go to die.

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One thing that stands out is Glenoma is probably the hottest location west of the Cascades in Washington, at least in offshore flow scenarios. It makes sense when you look at the fairly straight E-W orientation of the middle Cowlitz River valley and the steep terrain on all sides as it approaches White Pass. Similarly the Skagit River Valley around Nehalem/Marblemount gets quite hot.

Its interesting that you say that because Glenoma lies right on HWY 12. I grew up hunting in that area. I vividly remember the weather as child-teenager. It was always "muggy" near the road, but when we got up onto the higher elevation logging roads (naturally of course) the temps dived quickly. It was surreal to me as a child. 

 

I would have to agree with you on the topography as the reasoning behind Glenoma being the warm(est) locale in western WA. 

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Its interesting that you say that because Glenoma lies right on HWY 12. I grew up hunting in that area. I vividly remember the weather as child-teenager. It was always "muggy" near the road, but when we got up onto the higher elevation logging roads (naturally of course) the temps dived quickly. It was surreal to me as a child.

 

I would have to agree with you on the topography as the reasoning behind Glenoma being the warm(est) locale in western WA.

I don't think he meant it was the warmest as far as averages. Just the warmest as far as potential for extremes.
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Record low: 20 at Cascade Tunnell on 8/19 and 8/20/1896. Few stations in 1896 so this reading is tough to corroborate, however Wenatchee fell to 35 on 8/10/1896.

 

 

Just in case the reading is not accurate, the next coldest might be 23 at Bumping Lake on 8/23/1910?

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Just in case the reading is not accurate, the next coldest might be 23 at Bumping Lake on 8/23/1910?

23 at Cle Elum on 8/24/1910 and at Bumping Lake at 8/23/1910. There was also an unofficial 19 at Camp Muir on 8/27/2010 and a 21 at the same location on 8/31/2008.

 

The terrain constriction downstream from Bumping Lake largely accounts for the cold-air pooling ability of that area.

The Pacific Northwest: Where storms go to die.

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The same is true in other mountain areas as well.    There is more seasonal lag.   In the Cascades, at Crater Lake, for example, April is almost as cold as November, which isn't true in the low land valleys to the east.

 

Of course places near the ocean should also experience seasonal lag since it takes longer to heat up large bodies of water than land that is far away from the ocean.   That's what makes the early season cold snaps on the West Coast interesting and unexpected.   Along the coast, October records "should" be colder than April records and March records "should" colder than November records.   Of course records do produce unexpected anomalies, but the coast line of the Pacific Northwest has had many early season cold spells, even in comparison to later in winter, rather than just a few unexpected anomalies.

 

 

I'm going to guess that this has something to do with airmasses warming and cooling "from the ground on up" during the spring and fall, respectively?  So that the changing effects of sun angle and daylight are felt first in the valleys/basins, and later on in the highlands.  Especially in the Western U.S. where the rugged terrain makes us especially prone to valley inversions in the fall/winter.  Inversions reduce winter lag in the lowlands but may have a slight opposite effect in the mountains.

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  • 6 months later...

For what it's worth, I ran across a 99 degree reading at Mottinger, WA on 10/7/1911. However, this may have been an over-exposed reading and it's also offset by one day from what seems to have been the warmest day that month (the 8th). On that day, Pendleton hit 93 and both Hermiston and Echo reached 92. These are monthly records at all three stations, and they are the warmest readings from that month outside of Mottinger. 

 

Mottinger also recorded 98 on 4/28/1926 and 98 on 10/2/1943, as noted above. So it's definitely a location that is capable of seeing very warm temperatures, even by basin standards. However, the 1926 and 1943 readings are well corroborated by other readings in the basin, while the 1911 reading is not. Who knows, maybe their thermo was over-exposed in 1911 but was better sheltered in later decades?

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Also, Hanford possibly reached 87 on 3/24/1939. The monthly state report only lists 82 degrees for Hanford on the 24th, but this could have been a typo. Conversely, the 87 degree reading @ the WRCC could have been a typo:

 

http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?wa3444

 

This was definitely a major heat wave for March. Benton City hit 84 degrees that day, and Vancouver hit 78 on the 22nd. 

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  • 2 months later...

I was going through some data for Fort Colville and noticed a 12F reading (real tmin, not a 7am obs) on September 27, 1873. This is within 1F of the current WA monthly state record of 11F, as referenced in the opening post of this thread. I would imagine lower readings were observed in areas where stations had not yet been established. Specifically thinking of locations like Republic, Chewelah, Chesaw, etc. 

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  • 4 months later...
Record low: 20 at Cascade Tunnell on 8/19 and 8/20/1896. Few stations in 1896 so this reading is tough to corroborate, however Wenatchee fell to 35 on 8/10/1896.

 

 

Supposedly Cascade Tunnel also hit 20 on 8/27/1896 and 8/28/1926.

 

Berne, just to the east of Cascade Tunnel has supposedly reported lower August temperatures.

 

16 on 8/23/1936

16 on 8/24/1936

18 on 8/25/1936

20 on 8/29/1936

 

1936 seems to be the only year that temperatures were that cold in August, and other stations in the mountains, although cool during that time period, don't seem to be abnormally cold, so maybe those readings aren't legitimate?  

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Supposedly Cascade Tunnel also hit 20 on 8/27/1896 and 8/28/1926.

 

Berne, just to the east of Cascade Tunnel has supposedly reported lower August temperatures.

 

16 on 8/23/1936

16 on 8/24/1936

18 on 8/25/1936

20 on 8/29/1936

 

1936 seems to be the only year that temperatures were that cold in August, and other stations in the mountains, although cool during that time period, don't seem to be abnormally cold, so maybe those readings aren't legitimate?  

 

I can tell you for a fact there was a heatwave going on in late August 1936. Darrington, on the west side, hit 105 on 8/28 that year (late season record), followed by another record high of 96 on the 29th. This tells me any record cold on the east side would be extremely suspect on those days. 

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I can tell you for a fact there was a heatwave going on in late August 1936. Darrington, on the west side, hit 105 on 8/28 that year (late season record), followed by another record high of 96 on the 29th. This tells me any record cold on the east side would be extremely suspect on those days. 

 

At the Paradise Ranger Station, the heatwave you are referring to was quickly followed by a cool period around those dates, but it doesn't seem extremely cold. I guess I can see the area farther north being a day ahead for the cold air, but still 16 seems too low.   The 23rd and 24th were also cool at Paradise, but nothing really out of the ordinary.  

 

Here is the data from the Paradise Ranger Station:

 

paradise.JPG

 

The readings mentioned do seem suspect, but I thought I would mention them anyway, just in case.  

 

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