Sunday, September 22, 2019
The Steamboat Springs area awoke to a chilly 28 F low temperature early this Sunday morning, but brilliant sunny skies are quickly raising temperatures toward our average high of 70 F. The jet stream is forecast to be just to our north most of this work week, so dry and breezy weather is expected until a large storm develops to our west and brings the chance of unsettled weather around Friday.
The Autumnal Equinox (from the Latin and literally meaning equal night. i.e. twelve hours of day and night across the planet) occurs at 1:50 am MDT early Monday morning, and coincidentally this is when our average high temperature drops below 70 F until next year.
And we will see high temperatures around that average and low temperatures a bit below our average of 33 F for most of the work week as the current storm over the West Coast splits early in the work week, as best captured by last Thursday’s European ECMWF forecast. While the southern part of the split forms and eddy over the Desert Southwest that may be drawn near our area by another incoming Pacific storm around Friday, the northern part is absorbed into the fast-moving jet stream just to our north. So while the weather will remain dry, we will likely see breezy afternoons as the northern jet stream encroaches on northern Colorado.
Enjoy the pleasant and seasonable weather as it looks to turn unsettled by Friday, with storminess possible into the weekend. The culprit is a Pacific storm that is forecast to travel across the Gulf of Alaska and mix with some quite cold air from western Canada and the Hudson Bay region. As this storm travels down the west coast of North America and broadens early in the work week, it dislodges the Desert Southwest eddy eastward by Thursday.
While most of the Deseret Southwest eddy will remain to our south, moisture will increase over our area as the storm moves eastward across northern New Mexico. Additionally, cold air associated with the West Coast storm washes over the northwestern quarter of the U.S., creating a frontal boundary separating the cool air to the north and the warm air to the south that will focus precipitation.
There is enough uncertainty with how this all occurs that the forecast for our area will undoubtedly change by my next weather narrative on Thursday, but right now I would expect unsettled weather on Friday turning cooler and stormier on Saturday as the frontal boundary approaches our area. Eventually, weather forecast models agree the West Coast storm will move inland and over our area around the following midweek, with unsettled weather persisting until after that storm passes through.