For the past two weeks, Thursdays have been our lucky day when it comes to systems impacting Utah. The last two storms were similar in that they both arrived late on Wednesday and cleared out on Friday. They both had cold origins and delivered similar amounts of snowfall. This upcoming Thursday will be no different, at least in terms of timing, the system itself is a bit different.
Beautiful Fall weather will be the order of business through Tuesday as a dominate ridge of high pressure keeps us warm and dry. Things start to change on Wednesday as a cut-off Low drops into the western Great Basin and eventually into Southern Nevada/California. If you’ve been a regular reader of WSF over the past few years, you’ll know how much of a headache these cut-off lows can be. Because they “cut-off” from the main flow of the jet stream, they become very difficult to forecast their exact track and timing as they meander aimlessly. They can, however, bring copious amounts of precipitation due to their generally slow movement.
This particular Low is currently progged by both the GFS and European model to slowly drift Northeast from SoCal into Southern Utah and eventually Colorado. Current timing would bring it through starting Wednesday night, continuing through Friday (sound familiar?) I personally keep Excel spreadsheets of every storm that impacts Utah (it may sound nerdy, but it’s the best way to learn from past storms). Over the past 2 years, we have seen over a dozen storm systems that I classified as “cut-off” Lows. Most of these drifted through Northern Arizona and Southern Utah. Most of these systems also tracked farther south than the models were suggesting. Something to keep in mind . . . If the Low were to track through S. Utah as currently suggested, then Southern and Central Utah mountains could see their first significant snowfall above 8,000 ft. The Wasatch may not see quite as much, although a threat from both a trailing wave and wrap-around moisture does exist. However, if this Low does track farther south, then we could get totally skunked.
Overall, this is a warmer system too. It has cold origins, but after it drops south and spins for awhile, it will see a bit of an ‘airmass modification’ that will warm it up a bit. Snow levels in Northern Utah will likely be around 6-7K feet with snow levels around 8K feet in Southern Utah.
Looks like we dry out for next weekend again… Not going to bother looking beyond Day 7 as the models are notoriously poor with long range forecasting in transition months like October.
More details on the upcoming storm as we get closer . . .