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2024 Hennepin County All -Jurisdiction Hazard Mitigation Plan <br />Volume 2 — Hazard Inventory <br />which have shown very slight decreases over that same period. <br />Winter and nighttime -driven warming is consistent across the planet and is especially pronounced in areas <br />with long and severe winters —when surface heat that would normally escape into space is trapped by <br />the growing concentration of greenhouse gases. This warming has reduced the availability and depth of <br />cold air masses, such that cold air outbreaks are not as frequent or severe as they were historically, while <br />mild winter air masses are now more frequent and often warmer than was typical historically. For <br />instance, GRAPHIC 4.3.1C shows that daily minimum temperatures of -20' F or lower are now less <br />common in the Twin Cities than in any other period back to 1873. <br />GRAPHIC 4.3.1C Frequency of -20' F low temperatures in the Twin Cities. Data source: Applied Climate <br />Information System, accessed via https://www.dnr.state.mn.us/climate/historical/acis_stn_meta.htm1. <br />Number of Daily Minimum Temperatures -200 F or Lower <br />Twin Cities, 1873-2023 <br />27 <br />24 <br />21 <br />18 <br />15 <br />12 <br />9 <br />6 <br />lu 1111111d I � m� 1 1$ $� mobs � mI � �1 I m� m 11� �� �m h <br />r� r� w m m O O rH N N M M d' Ln Ln l0 l0 F� w Oo 01 01 O rH rH N <br />00 00 00 00 00 0) 0) 0) 0) 0) 0) 0) 0) 0) 0) 0) 0) 0) 0) 0) 0) 0) O O O O <br />Across Minnesota and the region, this warming has led to far more warm records than cold records being <br />set. Since the year 2000, the Twin Cities airport has set 6.7 times more records for highest daily maximum <br />and highest daily minimum temperature, than for lowest daily minimum and lowest daily maximum <br />temperature (shown in GRAPHIC 4.3.111)). These recent years representjust 16% of the station history but <br />account for 33% of the warm records and only 5% of the cold records. <br />GRAPHIC 4.3.111) Number and types of daily temperature records set from 2000 through 2023 at the <br />long-term Twin Cities observing site, currently at the MSP airport. Source: Threaded Extremes <br />(https://threadex.rcc-acis.org/) <br />48 <br />