The Amazing June Heat Wave of 2012. Part 1: The West and Plains June 23-27

The Amazing June Heat Wave of 2012. Part 1: The West and Plains June 23-27

One of the most intense heat waves in U.S. history has enveloped portions of the western plains and Midwest and has now spread eastward. All-time heat records have fallen at a number of significant weather stations. And it is still just June. Is this a prelude for the coming summer or just a flash in the pan?

NOTE: This is Part 1 of two blogs, Part 2 will focus on the heat wave in the eastern third of the country and will be posted on Sunday, July 1st.

The Set Up for the Heat Wave

June had been a warm but not excessively so month until around June 20-23rd when an upper level high pressure dome that had been centered over the Baja of Mexico began to move/expand northeastward and strengthen dramatically. Between June 23 and June 27 this dome remained nearly stationary over the southern plains and maintained its strength.



The water vapor image for 3Z on June 23 shows a deep trough over the Pacific Ocean west of California amplifying the high pressure ridge over the southwest and southern plains. Image from UNYSYS GOES West satellite.

The daily 500-millibar upper analysis charts for this period are shown below:



500 mb heights at 12Z on June 20, 2012. Image from NOAA Daily Weather Map.



500 mb heights at 12Z on June 22, 2012. Image from NOAA Daily Weather Map.



500 mb heights at 12Z on June 25, 2012. Image from NOAA Daily Weather Map.

The air aloft became so abnormally warm that the NWS office in Dodge City focused on how intense the air aloft was in their daily discussions. At the 850 millibar level (about 5000’) the temperature was averaging an amazing 30°C (86°F) at the 5 a.m. (12Z) observation times on June 23-27!

The heat at surface level reached its greatest extent on June 26th, although the period of all-time records broken ranged from June 23 to June 27.

Here is a surface temperature map for 5p.m CST time on June 26:



Surface temperature map for 5 p.m. CST on June 26th when the heat wave was at its peak. Note that the white shaded region represents temperatures of 105°+ and the white outlined area inside the white region represents 110°+. Map from UCAR.



Maximum and minimum temperatures for select stations on June 26th. NOAA Daily Weather Map. An interesting fact the exemplifies the magnitude of the Pacific trough and plains ridge is that it was snowing in the mountains along the border of Idaho and Montana above 7000' at the same time it was 111° in Miles City, Montana.

Records set in the West and Plains June 22-27

COLORADO

Perhaps the single most impressive record broken of all was the 114°F recorded at Las Animas, Colorado on June 23rd. This tied the hottest temperature ever measured during any month anywhere in the entire state of Colorado (114° has been recorded in the past at Las Animas on July 1, 1933 and Sedgwick on July 11, 1954).

All-time heat records (for any month) were also set or tied in Denver with 105° on both June 25 and June 26 (tied with 105° on July 20, 2005 and Aug. 8, 1878), Colorado Springs with 101° on June 26 (previous record of 100° set on five previous occasions including June 24 and June 25), Lamar hit 112° on June 27 (previous record 111° on July 13, 1934 and also on June 26, 2012). In far northeastern Colorado all-time heat records were also set at Yuma (111°) and Holyoke (110°) on June 27th. June all-time monthly heat records were set at virtually every site in the state east of the Rocky Mountain front range (like the 102°s at Fort Collins and Trinidad).

Denver reached 100°+ for a record tying five consecutive days June 22-16. Pueblo recorded six consecutive 105°+ days June 22-27, its longest streak of such heat on record (its maximum was 107° on June 24th, two degrees short of its all-time record of 109° and one degree short of its June record of 108° set on June 29, 1990).

The intense heat exacerbated the terrible wild fires in the Rocky Mountain foothill communities of Fort Collins, Boulder, and Colorado Springs where around 600 homes have been lost and at least two lives lost.

KANSAS

Dodge City recorded its all-time (any month) record high of 111° on June 27th (previous record of 110° set on 3 previous occasions including June 26, 2011 AND June 26, 2012!). This is a particularly significant measurement since Dodge City has one of the longest continuous periods of record in the U.S.: since September 1874. Hill City was the state’s hottest spot during the heat wave with 115° measured on both June 26th and June 27th. This was a monthly record for the site but not all-time (117° in July 1936). It was also just one degree shy of the Kansas state monthly all-time June heat record (116° at Hugoton on June 25, 1911). An unofficial 118° was reported from Norton Dam on June 27th by a RAWS site.

All-time records were broken or tied also at Colby (112°, old record 110° in 1953) and Tribune with 111° (a sort POR here).

Most locations in the western third of Kansas broke their all-time June monthly records such as Goodland’s 110° on June 24 and June 25 (old June record was 109° on June 18, 1936).

NEBRASKA

An all-time Nebraska state monthly heat record for June was set at McCook with 115° on June 26 (previous record was 114° at Franklin on June 26, 1936). This was also the all-time (any month) record for McCook. Benkelman reached an all-time high of 114°. Sidney also broke their all-time any month record with 111° the same day. Interestingly, the high temp in Sidney may have been the result of heat burst since the temperature rose from 102° at 3:52 p.m to 111° by 4:05 p.m (a 9° rise in 14 minutes!). Thunderstorms were in the vicinity. This broke the previous June monthly record by an astonishing 7°!

MONTANA

An all-time heat record (any month) was set at Miles City with 111° on June 26. However, this reading was made at the airport (POR 1937-current) whereas a temperature of 113° was recorded at the Miles City COOP downtown site on July 20, 1960 (POR 1893-1982). In any case, the 111° was just one degree short of the Montana state monthly June record (112° at Baker in June 2002).

NEW MEXICO

The excessive heat only affected the northeastern third of New Mexico.
Santa Fe and Tucumcari both came within 1° of their respective all-time heat (any month) records: Santa Fe 99° on June 23 and Tucumcari 108° on June 27. This was a June monthly record for Tucumcari, but Santa Fe has seen 100° on June 5, 2010.

Could this be the Beginning of Another ‘Summer of 1936'?

The only previous June heat waves in U.S. history that compare to the current one were those of 1934, 1936, and 1954. The summer of 1934 went on to be the warmest on record for the U.S. (74.6° June-August average) and July 1936 the single hottest month on record (77.4° average).

Ominously, some of the June records that have so far been set this month have eclipsed those of June 1934 and 1936 (1954 turned out be a summer of only slightly above long-term average normal temperature).

I’ll be posting part two of this blog (covering the heat records in the eastern third of the country set during the period of June 28-30) on Sunday July 1st.

Christopher C. Burt
Weather Historian