The headline is a direct quote from the National Weather Service!
Huge cold outbreak coming to Wyoming and Nebraska.
Note the next to last paragraph: “…some locations may break their record low by 10 to 15 degrees.” Ouch.
Also, a threat of heavy snow, with snowfall rates between 1 to 2 inches per hour
National Weather Service – 13 Oct 2018
An unusually cold outbreak is expected with very cold air already starting to work its way southward across the forecast area. Surface cold front has moved into the Colorado plains this afternoon and is stalled along the Laramie Range. Temperatures have fallen into the 40s with Cheyenne`s temperatures now at 50 F degrees after a high of 60 F earlier.
Expect this front to continue moving southwest into the mountains through tonight. Recent webcams along and east of I-25 show that any rainfall has switched to snow with snow reported in Douglas. This trend will continue into this evening .
Across far southeast Wyoming and far southwest Nebraska, (we) may need to extend the Winter Storm Warning in Banner, Kimball, and maybe even Scottsbluff county. Most ensemble members are more aggressive with precip amounts as well, so will
need to keep an eye on snowfall rates through this evening.
On theother hand, The HRRR and the NAM show an area of drier air near the surface at the onset of this event, mainly impacting areas between Laramie, Chugwater, and Cheyenne. This may cut snow totals locally, but will keep previous snow totals as is due to the threat of heavy snow and snowfall rates between 1 to 2 inches per hour for a few hours. (emphasis added)
Extended the Winter Weather Advisory into the rest of western Nebraska in addition to Niobrara county. 12z model runs continue the trend of showing higher QPF and snowfall amounts from Lusk southeast towards Chadron and Alliance through late this evening, so increased total snow accumulations. …Overnight temperatures in the teens to low 20s are expected with wind chills in the single digits above and below zero (below -17.7 C). Moderate to heavy snowfall should come to an end after midnight.
Very cold temperatures for this early in the season will be the main concern late Sunday and especially Sunday night. … With little or no wind, clearing skies, and a surface snow pack across much of the area, excellent radiational cooling is expected. Most of the area will likely have record low temperatures, and some locations may break their record low by 10 to 15 degrees. (emphasis added)
Continued to lower temperatures with lows mainly in the single digits across the region, including western Nebraska. Expect some readings down to -10 (-23.3C), such as the Laramie Valley and other sheltered valleys with a decent snowpack by early Monday morning.
Thanks to Don Villeneuve for this link
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October 13, 2018 at 10:54PM