Heat — Gosper, Nebraska

2023-08-19 to 2023-08-25 · Gosper, Nebraska

Wider weather episode

Across most of the 24-county South Central Nebraska area, the seven-day stretch from Saturday the 19th through Friday the 25th went down in the books as the overall-hottest week in between 11 and 35 years, and one of the hottest on record for so late in the summer, making for an especially scorching week as local high school athletic practices kicked into gear for the upcoming fall sports season (not to mention various other outdoor activities). Throughout the vast majority of the week, all of South Central Nebraska was under either an Excessive Heat Warning or a Heat Advisory, with the Warning mainly assigned to counties along/east of Highway 281 where peak afternoon/early evening heat index values were commonly 105-110 degrees (F), while slightly cooler peak heat index of 100-105 F typically prevailed within counties west of Highway 281. Based on data from a sampling of several long-term NWS Cooperative observer sites along with a few automated ASOS stations, this was officially the hottest week since 2012 at places such as Cambridge and Red Cloud, since 1991 at Gothenburg, and more impressively...the hottest since 1988 at Hastings and Osceola. Although a bit of a warm outlier compared to most sites, the Grand Island ASOS (Central Nebraska Regional Airport) actually registered its overall-hottest week in 68 years (since 1955)! Focusing specifically on observations from the Hastings Municipal Airport ASOS, which reasonably-represented conditions across much of South Central Nebraska, the overall-average temperature for the week was 86.5 F...derived from an average daily high temperature of 100.7 F, and an average daily low of 72.3 F. This marked the overall-hottest week since June 19-25, 1988 (87.3 F). Perhaps more impressively though, this Aug. 19-25 heat wave made for the overall-hottest week on record so late into the summer season in Hastings, edging out an 86.0 F average during the same week in 1936. Among other notable stats at Hastings: 1) The stretch of four consecutive days of 100+ F high temperatures from Aug. 21-24 was the longest in 28 years (since a five-day stretch in July 1995)...2) The high temperature of 104 F on the 21st was the hottest temperature recorded that late in the year in 68 years...since it reached 104 F on Aug. 27, 1955...3) On the low temperature side of things, the five-day stretch of 72+ F lows between the 19th-23rd marked the longest in 12 years...since a 7-day run in July 2011.

Turning to the meteorological background behind this oppressive late-summer heat blast, not surprisingly it was driven by an unusually strong and persistent dome of high pressure in the mid-upper levels. Specifically at 500 millibars, the heart of a sprawling anticyclone centered over Oklahoma on the 18th gradually shifted northward over the heart of the NE/IA/KS/MO region from the 19th-20th, then peaked in intensity between the 21st-23rd as heights reached the rare 600 decameter threshold. Finally, from the 24th into the 25th, the center of the upper ridge gradually sunk back southward to over the Southern Plains, flattened by a shortwave trough tracking along/near the United States-Canada border. At the surface, this heat wave arrived into South Central Nebraska with a vengeance on the 19th as high temperatures soared to between 98-104 F in most places (generally 10+ degrees hotter than the previous day). Adding to the abrupt misery on the 19th were high humidity levels (dewpoints generally upper 60s-low 70s F) and light winds mainly only 5-10 MPH. Although the 20th was slightly cooler (highs mainly in the 90s), the mercury really climbed between the 21st-24th as most places topped out between 100-105 F each afternoon (fortunately, most of these hottest afternoons featured southerly breezes of 10-20 MPH, providing some limited relief). At long last, the aforementioned upper trough sent a slow-moving cold front southward across South Central Nebraska on the 25th, with highs only reaching the upper 80s-mid 90s F in most areas, except for one last round of near-100 F readings near the Kansas border where the front was last to arrive. The following day on Saturday the 26th, highs only reached the upper 70s-low 80s area-wide...a most-welcomed respite from the heat wave. As for local heat impacts, one of the primary ones involved high schools and particularly athletic practices for football and softball. Per media reports, many schools opted to move football practices indoors or to the early morning hours during this week leading up to the season-opening games for most local teams.

Source: NOAA Storm Events Database, event_id 1129771. Narrative written by the NWS forecast office that issued the report.