March 31, 2023

Why is Freezing at 32°F? And A Snowy Weekend Ahead in the Cascades. All in My New Podcast.

Did you ever wonder why freezing on the Fahrenheit scale is at 32?

Why that number?  Why not 0 or 50?

The answer to the question will be answered in my podcast! (see below for details)


And before the talk about temperature, I provide the forecast, and it is a snowy one for our mountains.

Today, a front will be moving through (see satellite photo below), behind which there is cool, unstable air.


This cool, unstable air, forced to rise on the local mountains, will produce heavy snow in the Cascades, with several feet at higher elevations.  Good for skiers, good for weather resources, but potentially causing dangerous conditions in the passes.

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19 comments:

  1. I prefer the finer Fahrenheit scale to the coarser Celsius/centigrade scale. 1 Celsius/centigrade degree is equal in magnitude to 1.8 Fahrenheit degrees. There's no really legitimate practical reason - I'm just anal about precision.

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  2. Yesterday's frontal system was fairly unimpressive even for the time year, especially when compared with the powerful late-season storms this area has seen in recent years. I measured a max wind gust of 32mph, while BLI topped out at 36mph.

    Last year in particular saw some very impressive late season storms. A storm on 4/4/22 produced a wind gust of 49mph at my location, the highest April wind gust in my record, and an arguably even more impressive dry season storm on 5/18/22 produced a 42mph gust - the first wind gust in the 40s I've measured during May.

    My CoCoRahs gauge ended up with 0.2" and BLI reported 0.18" for yesterdays event. The March monthly precip total at BLI was 1.77" (normal is 3.36") making March 2023 the 10th driest March on record. The water year total precip at BLI now stands at 16.62", or about 69% of the 24.18" that would normally have fallen by today and very close to the all time record of 15.84" which had fallen to date during the 1993-1994 water year.

    The calendar year has been equally as parched with a total of just 4.98" (the normal total for January alone is 4.49") and is just barely more than the record driest calendar year to date, 1985, with 4.85". Normally, 10.8" would have fallen since the beginning of the year meaning that the current total stands at a rather alarming 46% of normal.

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  3. Sometime in school, can't remember when exactly, we were taught this conversion equation from Fahrenheit to Centigrade:
    C/F-32=5/9

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  4. Friend: Given that BLI (Bellingham Airport) is notoriously "banana belt," adjacent to Bellingham Bay. Others have commented about BLI's YTD being low, "parched," but I don't think it's much of a harbinger regarding climate or water supply. I'm also a CoCoRaHS observer. Precipitation at BLI is routinely an outlier; within a mile or two there's always more rain, and there's a CoCoRaHS station on the west end of Lake Samish that routinely reports twice the rainfall recorded near the Bay. I'm in a valley inland, and yes we're not setting records this year, but other years have been drier. I think this area (watershed) is still well within the range of normal. Some decades (the 1950's) were much drier. River flow? There's been a LOT of snow this year, winter conditions began in November with very cold nights (sub-zero), and "what's frozen doesn't flow." BTW, I woke up to .7" snow this morning, .20" precip for the 24 hours. "Parched, we are not" in WRIA1" imho.

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    1. You are missing the point on BLI. It is a standard reference point with many years of data. The statements by "Friend" about BLI are with respect to deviations from the average for that location. Good yearly and monthly summaries are available here:

      https://www.wrh.noaa.gov/climate/yeardisp.php?stn=KBLI&wfo=sew&year=2023&span=Calendar+Year

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    2. Yes MAC, I know that BLI is a "standard reference point" with many years of data, yada-yada. IMHO, it's a lousy reference point. PRISM's historic data also includes my zone, the Glacier area, with data that goes back to 1898. I know what the figures are for Bellingham-Blaine-Clearbrook, and I've seen how that information has been used - dare I say "misused" - to characterize the county's annual rainfall statistics. Those three points (Sahara Triangle) lie in the western third of the county without including the 'headwaters' (mountainous, rainy-snowy) eastern two thirds of the watershed. I look at all the facts, MAC - and encourage others to also. Best.

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  5. On another recent blog, a commenter responded to one of my comments about the pronounced precipitation deficit that BLI has been experiencing over the past year or so with a comment similar to yours and I will reply to you with a comment similar to the one with which I replied to said commenter:

    It was not by accident that I never suggested in any way that the abnormally dry conditions which the BLI has reported are anything other than a relatively localized anomaly.

    I also, again not by accident, made no mention of climate or water supply. My comments regarding the BLI drought are simply to report the data in the context of how remarkably anomalous it is (i.e. near record dryness for both calendar and water year-to-date).

    I'm a big time weather buff and I, as I suspect is the case for most weather buffs, am fascinated by weather extremes and I dare say that the many notably dry months that BLI has experienced over the past year or so qualify as such.

    As you're probably aware, given your obviously extensive knowledge of the weather history of Whatcom County, there are two other sites in the County for which data is available via the NWS NowData portal. These are known as Bellingham 3 SSW which is located at, or near, the Post Point Wastewater Treatment Plant in Fairhaven, and Clearbrook which is located near the confluence of Johnson and Squaw Creeks to the southeast of where the BNSF tracks cross Van Buren Rd roughly midway between Lynden and Sumas.

    Bellingham 3 SSW has reported total calendar year-to-date precipitation of 7.36". The normal total is 11.24" so the site has received ~65% of its normal year-to-date precipitation. It has received 21.42" of total precipitation for the water year-to-date out of a normal total of 25.36" or ~85% of normal.

    Clearbrook has received 9.63" for the calendar year-to-date out of a normal total of 16.13" or ~60% of normal. It has received 26.6" of total precipitation for the water year-to-date out of a normal total of 34.74" or ~77% of the normal total.

    So, while my point stands that BLI, in particular, has experienced historically dry conditions during the relatively recent past, you are absolutely correct that other not too distant locations have not been nearly so affected.

    An observation of mine has been that precipitation tends to be subject to much greater spatiotemporal variation than temperature at the local and regional scales and, while I haven't checked the data, I suspect that the temperature anomalies that BLI, Bellingham 3 SSW and Clearbrook have experienced over the past year or so are much more similar so one another than the precipitation anomalies. All this information just serves to deepen my love for and fascination with weather and it's infinite quirks and vagaries.

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  6. On the subject of water supply, I just checked the NRCS and USGS interactive maps and it appears that many of the gauges on monitored streams in Washington indicate flow/discharge that's much below normal for this time of year including those on the North Fork Nooksack River below the slopes of Church Mountain, the Middle Fork Nooksack River near the intersection of USFS Road 38 and Mosquito Lake Rd, the South Fork Nooksack River at Saxon bridge, which is currently at its all-time low discharge for this day of the year, and the Nooksack River at Ferndale.

    With regard to snowpack, I would contest the assertion that there's been "a LOT of snow this year" as a general statement. While some areas of the state have received above normal snowfall and currently support a healthy snowpack, the North Puget Sound basin has consistently lagged other areas of the state.

    The Mount Baker Ski Area has certainly not exactly had a banner year. It currently reports total seasonal snowfall of 527" as of March 31. The average April snowfall at the ski area over the past 12 Aprils is ~59" so I'd say it's rather likely that the ski area will end this season with total snowfall of less than 600". This has happened during only 19 of the 52 seasons for which there is data available and, while certainly not a catastrophe by any stretch of the imagination, it is indeed below the reported seasonal average of 641" - and in a La Nina winter no less.

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  7. While I recognize that snow melt can be a major component of stream flow, I would think that this is primarily the case during atmospheric river/pineapple express events during winter as well as at the end of the wet season and during the early portions of the dry season (i.e. the spring freshet). That said, I would assume that during typical winter/wet season conditions, stream flow is primarily a function of rainfall/runoff.

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  8. Dear Friend: The ski area received 13" addl snow since March 31 - 540" as of this morning, and it's been coming down gangbusters all day (4" in Glacier in less than 12 hours). That said, some winters we have a great deal of rain, "wet, flowing" precipitation and this winter there have been a greater proportion of snowy days than what's quite common. I've been observing here in the headwaters for 49+ years, and even if the ski area's total SNOW-fall totals less than 600" (and that's not certain), that's still very near what you computed as a 'seasonal average' of 641". Jeepers. This means what in respect to the characterization ("parched") re BLI's calendar year rainfall stats? My thinking is that there's no correlation. My humble opinion remains that this watershed area remains within 'range of normal,' which is a highly variable at the best (and worst) of times. Happier thoughts.

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    1. We'll see whether the ski area ends up with less than 600" for the season but if I was a betting man I would bet that it will both because of the historical average April snowfall as well as the current weather forecasts. I would also wager that the chances that the ski area will receive its normal seasonal snowfall total, or more, are very low.

      My point is that seasonal snowfall totals at Heather Meadows of less than 600" are historically uncommon. Furthermore, the current snow pack, in terms of snow water equivalent, in the North Puget Sound Basin is below normal and, in fact, is the lowest of any of the NRCS-monitored basins in the state. Thus, my (correct) assertion that we have not had a lot of snow this season (in the North Puget Sound basin).

      I assume that you're indicating that you believe that the exceptionally low stream flow throughout the Nooksack River and its three forks is simply due to the fact that an unusual proportion of the precipitation which has occurred recently has been frozen and has not contributed to stream flow in the form of runoff. This may be the case and, if so, it would seem to me that such a case is fairly unusual though certainly not impossible. It has been a fairly cold wet season overall. However, it's also the case that it's been an rather dry wet season overall.

      This is illustrated by the fact that, in addition to the below normal snow pack in the North Puget Sound Basin, all of Western Whatcom County has received below normal precipitation for both the calendar and water years-to-date as demonstrated by the negative precipitation anomalies at the three sites I mentioned in my previous comment, though it is indisputable that BLI is at the forefront in that regard.

      So, is there a correlation between the fact that the local snow pack is below normal and the fact that Western Whatcom County, in general, as received below normal precipitation for both the calendar and water years? I would contend that there is a very strong correlation in that regard and that, in fact, the cause of the below normal snow pack and below normal calendar and water year precipitation totals is that there simply has been less precipitation, both frozen and liquid, throughout Western Whatcom County and the Nooksack basin than normal. QED

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  9. I just checked the precipitation anomaly map for Washington from the Western Regional Climate Center which shows precipitation anomalies for an array of time periods from the most recent 7 days to the most recent 36 months.

    With regard to Whatcom County, the only time frame for which any portion of the County has received at least normal precipitation during the most recent 12 months is the most recent 14 day time period and then only for the westernmost portions of the County. For the time periods 7 days, 30 days, 60 days, 90 days, 6 months and 12 months all portions of Whatcom County show below normal precipitation. Only when looking at the most recent 24 month and 36 month time periods has Whatcom County generally received at least normal precipitation.

    So, I would, I think correctly, assert that below normal precipitation has held sway over Whatcom County as a whole over the past year or so.

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  10. Since you mentioned that you participate in CoCoRahs and, presumably, are located in Glacier, I decided to take a look at the data from what I presume to be your station (WA-WC-70). I compared the monthly precipitation totals from that station with the historical monthly average rainfall totals for the 1981-2010 (the most recent available) climate normal period for the Glacier Ranger Station as reported by the Western Regional Climate Center.

    The average monthly precipitation totals for the Glacier Ranger Station for the 1981-2010 climate normal period per the Western Regional Climate Center are as follows:

    January - 9.46"
    February - 10.35"
    March - 5.91"
    April - 5.67"
    May - 3.17"
    June - 4.43"
    July - 4.83"
    August - 2.76"
    September - 4.22"
    October - 6.85"
    November - 9.94"
    December - 10.39"
    Annual average total - 77.99"

    The monthly precipitation data from CoCoRahs station WA-WC-70 are as follows:

    January 2022 - 8.79"
    February 2022 - 3.99"
    March 2022 - 7.12"
    April 2022 - 5.95"
    May 2022 - 5.17"
    June 2022 - 5.48"
    July 2022 - 1.16"
    August 2022 - 0.32"
    September 2022 - 0.17"
    October 2022 - 5.41"
    November 2022 - 7.88"
    December 2022 - 10.15"
    January 2023 - 5.05"
    February 2023 - 5.28"
    March 2023 - 4.08"

    So, the water year-to-date total precip for this site is 37.85" compared to a normal total of 52.9" or ~72% of average and the calendar year-to-date (January - March 2023) total precip for this site is 14.41" compared to a normal total of 25.72" or ~56% of average. The 2022 calendar year total precip for this site is 52.59" compared to a normal annual total of 77.99" or ~67% of average. These anomalies compare quite favorably with those reported by the sites that I mentioned previously which are located in the lowlands of the western portion of the County.

    Thus, my characterization of a Whatcom County drought which has persisted for the past year or so appear to be well supported by all of the available data.

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  11. I would add, as a caveat, that weather records for the Glacier Ranger Station as shown by the Western Regional Climate Center are somewhat sparse and should thus be taken with a grain of salt. That said, among the available records for the site, which extend from 1914 through 2000, the lowest monthly precipitation total for any month of September is 0.23" during 1942. With said grain of salt in mind, the 0.17" of precipitation that was reported for September 2022 at CoCoRahs site WA-WC-70 would constitute an all-time record low for September precipitation at a site with a period of record of nearly a century.

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  12. In the interest of thoroughness, I also checked PRISM's precipitation anomaly map and found, unsurprisingly, that the vast majority of Whatcom County has had negative precipitation anomalies for every quarter from that of June 2022 - August 2022 through the most recent quarter, January 2023 - March 2023. I also checked the precipitation anomaly map for the 2022 calendar year and again, unsurprisingly, found that the anomaly for the vast majority of Whatcom County, including the central and eastern portions in particular, is negative. At this point, the data is absolutely conclusive that Whatcom County has been in a continuous state of drought of varying degrees for the majority of the past year if not longer depending on the specific location within the County.

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  13. Because of my previous lack of familiarity with PRISM, I didn't know how to retrieve the current normal climate data (1991-2020) through which it is available. The data appears to be estimated based on some kind of analysis rather than actual, measured values. I found that the estimated total annual average precipitation for a location at 935' in Glacier is 67.02"

    January 9.04
    February 6.07
    March 7.52
    April 4.6
    May 3.62
    June 3.13
    July 1.55
    August 1.97
    September 3.49
    October 7.12
    November 9.92
    December 9
    Annual 67.02

    Using these values rather the Western Regional Climate Center data, CoCoRahs site WA-WC-70 has a current water year-to-date precipitation deficit of 10.82" or ~78% of normal, a current calendar year precipitation deficit of 8.22" or ~64% of normal and a 2022 calendar year precipitation deficit of 14.44" or ~78% of normal.

    As before, these anomalies compare favorably with those reported by the previously mentioned sites located in the lowlands of the western portion of the County.

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  14. Both the western and eastern parts of Whatcom County remain in the abnormally dry category and the snow water equivalent for the Whatcom County Cascades remains at approximately 85% of normal. The last time Whatcom County had major amounts of above average precipitation was in November 2021, when major floods occurred as a result of 6 days of heavy rain.

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  15. MAC: I'm familiar with most of that "official" data, and I've commented many times that the statistics available online for quite a few locations in this watershed have lead to very poor models and erroneous conclusions. For decades I've made a point of making (and recording) thorough and useful observations, and it's not surprising that the spotty records lead to different conclusions, conclusions that seem erroneous given what observable (tangible) conditions truly are.

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