Thursday, December 4, 2014

Dramatic Temperature Drop November 29-30 2014 in the Plains

Christopher Burt, Weather Historian for Weatherunderground has documented in his blog the dramatic temperature drop in the plain states over the Thanksgiving weekend.

Near Record Drop in Temperature in Plains November 29-30

By: Christopher C. Burt , 9:13 PM GMT on December 01, 2014

Near Record Drop in Temperature in Plains November 29-30

A cold front passed through Montana and Wyoming on Saturday November 29th and then pushed south and east over the Great Plains dropping temperatures as much as 70° in a matter of hours.

Temperature change over the 24-hour period from 3 p.m. November 29th to 3 p.m. November 30th. In fact, even greater falls of temperature occurred at various sites over different periods of time. Map graphic courtesy of The Weather Channel.

Nebraska saw the most pronounced temperature drops with York falling from an all-time late-season record high of 81°F at 1:35 p.m. on November 29th to 10° by 7:30 a.m. November 30th. An amazing 71° drop in just 18 hours! Other sites in the state saw similar drops: Norfolk from 77° (also a late-season record high) at 3 p.m. to 8° by 8 a.m. (a 69° fall in 17 hours), Hastings 80° (late-season record high) to 11° from 1 p.m. to 8 a.m., Grand Island from 78° to 10°, and Valentine 71° to 3° (1 p.m. to 6 a.m.).

Douglas, Wyoming fell 36° in one hour between 7 p.m.-8 p.m. on November 29th, from 52° to 16°. The temperature was 60° at 2 p.m. and 11° by 10 p.m. In Livingston, Montana the temperature fell 26° in sixminutes: 47° at 7:53 a.m. to 21° by 7:59 a.m.! By noon it was down to 6°. Bozeman, Montana dropped from 49° at 8 a.m. (November 29th) to -22° at 5:42 a.m. (November 30th), a 71° drop within 24 hours, similar to York in Nebraska.

Historical Perspective

Amazing as these figures are they do not represent all-time record temperature changes for the U.S. The famous cold front of November 11, 1911 was the most extreme such on record. On that day an intense cold front swept quickly across the Great Plains and Midwest where Kansas City, Missouri fell from 76° to 11° in 12 hours. Oklahoma City fell from 83° to 17° and Springfield, Missouri from 80° to 13°. In all three cases the cities recorded both their daily record high and daily record low temperature for November 11th.

The thermograph trace from Springfield, Missouri actually shows that the high temp was at least 81° on November 11th at around 3:45 pm. It also shows that by midnight that same day the temperature had fallen to 10°. The ‘official’ range of temperature for the day of 80° to 13° is not correct if the thermograph is accurate. The office only reported hourly temps for their daily summary and concluded that the 11 p.m. temp of 13° was the lowest for the day when, in fact, it had reached 10° by midnight. The 81° high also occurred between hourly reports. A drop of 40° occurred in 15 minutes between 3:45 p.m. and 4:00 p.m. was observed and the 71° drop in eight hours is almost unprecedented in meteorological records, although two locations in Arkansas (Rogers and Fayetteville) measured a 72° drop in temperature during the same period from 81° to 9°. Graphic from NWS-Springfield office.

Chicago dropped from 74° at 1pm to 13° by midnight on the 11th, and the Monthly Weather Reviewstated "one man was overcome by heat and two others frozen to death in the short space of 24 hours" (sounds like a little journalistic license here!).

The following is a table of the various state high temperatures observed on November 11, 1911 and state low temperatures observed on November 12th and 13th:

But THE greatest temperature drop for any single location in the U.S. (and the world) was that which occurred at Browning, Montana on January 23-24, 1916 where the thermometer plunged 100° in 24 hours: from 44° around midday on the 23rd to -56° by the morning of the 24th. Fairfield, Montana once saw its temperature fall 84° in just 12 hours on December 24, 1924, from 63° at noon to -21° by midnight.

Conversely, Montana also holds the world record for the fastest rise in temperature for a 24-hour period when a Chinook rose the temperature from -54° at 9 a.m. on January 14, 1972 to +49° by 8 a.m. on January 15th. A 103° rise, and the greatest change in temperature ever officially measured on earth within a 24-hour period. The NWS investigation of this event can be read here.

NWS COOP observer Jim Wood and his instrument shelter at Loma, Montana where the famous (and officially investigated) world-record 103°F change in temperature occurred on January 14-15, 1972. Photo courtesy of NWS-Great Falls.

Christopher C. Burt
Weather Historian

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