SPM 09-20-2017: Gusty Winds and Snow for the Northern High Country

Issue Date: Wednesday, September 20, 2017
Issue Time: 10:45AM MDT

Summary:

The jet stream moved southeast yesterday with the front nose of the jet settling just north of Colorado. 100+ knot winds clipped the northwest corner of the state leading to a high wind advisory as the fast moving air aloft mixed down to the surface. Some mid-level energy also moved through northern Colorado, which helped trigger some rainfall and snow (at higher elevations) during the evening hours after the cold front passage. Elsewhere along the Front Range, downsloping winds lead to sunny skies and a windy afternoon and evening, especially along the Palmer Divide. Low relative humidity values were created by the descending air as it warmed adiabatically, and a Red Flag Warning was in place through last night. Early in the evening, a strong cold front pushed south and dropped temperatures 15-20F and produced windy conditions. Due to dew points in the 20s, negligible precipitation fell, but a lot of dust was kicked up. The cold front did moisten the lower atmosphere enough for the high terrain showers along the CO/WY border in the evening and overnight.

Over Routt County, two CoCoRaHS stations recorded 0.25 inches. A SNOTEL site in the Medicine Bow-Routt National Forest recorded 0.4 inches of precipitation from the late afternoon into early evening. Due to the cold front rapidly dropping temperatures, precipitation at higher elevations was in the form of snow. Webcams from Steamboat Ski Resort this morning show a light dusting of snow. Again, the real story yesterday were the wind gusts, which were quite impressive. Below is a handful of maximum gusts from around the state. There was no flooding reported on Tuesday.

Hayden – 48 mph
Steamboat – 40 mph
Gypsum – 48 mph
Berthoud Pass – 74 mph
Cottonwood Pass – 64 mph
Saguache Airport – 36 mph
Limon – 41 mph
Denver – 28 mph
Sterling – 46 mph

For an estimate of rainfall totals in your area, scroll down to the State Precipitation Map below.

Click Here For Map Overview

The map below shows radar-estimated, rainfall gage-adjusted Quantitative Precipitation Estimates (QPE) across Colorado. The map is updated daily during the operational season (May 1 – Sep 30) by 11AM. The following six layers are currently available: 24-hour, 48-hour and 72-hour total precipitation, as well as maximum 1-hour, 2-hour and 6-hour precipitation over the past 24 hour period (to estimate where flash flooding may have occurred). The accumulation ending time is 6AM of the date shown in the bottom right corner. Also shown optionally are fire burn areas since 2012. The home button in the top left corner resets the map to the original zoom.

Note: We have identified a possible underestimation in QPE over the southwest part of the state. We are working to on this issue, and will provide an update as soon as possible.