The greatest temperature change in a 24-hour period ever measured in the U.S.—and perhaps the world—occurred at Loma, Montana, on January 14-15, 1972. NWS COOP observer Jim Wood measured a temperature of –54°F in his Stevenson Shelter at 9 am on the morning of January 14. By that evening a powerful chinook wind enveloped the area with downsloping winds blowing a sustained 30-40 mph.
In a paper entitled “A National Temperature Record at Loma, Montana”, Mr. Wood is quoted as follows:
“Shortly after midnight, I woke to the sound of a howling wind. I dressed and read the temperature and could not believe it read 34° above [zero]. The severe southwest wind continued and by 6:00 am the temperature was in the mid-40°s. By 8 am it had reached 49° and never raised higher the rest of the day.”
NOAA verified the observation with an investigation of the event undertaken in 2012 by its National Climate Extremes Committee (NCEC). Note that 88° of the temperature rise actually occurred in just a 15-hour period between 9 am and midnight on January 14. Another way to picture just how extreme this was: imagine the 103° spread (–54° to 49°) spanning the range from 0° to 103°, or 17° to 120°, in just a 24-hour period!
This chinook event occurred over a wide area in the leeside of the Rocky Mountains of western Montana. Great Falls, 40 miles southwest of Loma, observed a 62° temperature rise (from –29° to 33°) during the same time period. Havre, 50 miles northeast of Loma, saw its temperature rise 79° from –36° to 43°. Numerous COOP sites in the region saw temperatures rises of 80° or more, including a 92° rise at the hamlet of Iliad (–42° to 50°).
|Figures 5 and 6. These 1972 daily weather maps for January 14, 1972 (top), and January 15 (bottom) illustrate the surface weather pattern that facilitated the occurrence of the strong chinook event that affected much of central Montana, resulting in the record-breaking 103° temperature rise in Loma. Image credit: NOAA/NWS Daily Weather Maps.|
Montana is no stranger to extreme temperature fluctuations. The state also holds the U.S. (and perhaps world) record for the greatest drop in temperature for a 24-hour period, when the temperature fell from 44° to –56° at Browning on January 23-24, 1916.
Here is the official NWS document on the event:loma
Our weather this week will be mainly uneventful compared to this weekend. Temps will gradually rise as we go through the week with our next weather event coming Thursday which will mainly be a light mix.
We had 8 inches of snow between the synoptic event and lake effect bringing our today to 24 inches for the season. Last night’s low dropped to 2.3° which was our coldest thus far.