Wasatch Weather Weenies

People keep asking me when it's going to snow.  My response? How the hell would I know? Things are grim.  It's OK to be cranky.   As a scientist, I like to look at the evidence.  I'm doing this at about 7:15 on a Wednesday night part way into a fine bottle of Chianti, which I find necessary to numb sting of the forecasts. Let's start with the GFS.  A paltry 0.04" of water and 0.7" of snow for Alta-Collins over the next week.  The Euro?  I don't have an equivalent graphic.  I've looked at the next 10 days.  it might have a few more scraps at times, but nothing to get excited about. The Utah Snow Ensemble?  Well, the Euro is in it along with 81 other forecasts from the European and US ensembles. It too is pretty grim.  The forecast below covers 10 days.  There's one member that produces just over 20 inches.  There's always hope.  There are 10 members total that produce more than 10 inches.  There's always hope...

A major transition in the structure of the jet stream will occur over the next few days, resulting in the development of an omega block over the Norh Pacific Basin and high-impact weather for northern California and the Northwest United States. The plot below is a combined sea level pressure (black contours) and dynamic tropopause (jet-stream level) forecast for 0000 UTC 18 November (5 PM MST Sunday). I have identified the jet stream over the North Pacific Basin and North America with a black line.  The forecast shows a deep low pressure system over the Sea of Okhutsk (at the tip of the L1 arrow).  Downstream of it, there is strong southerly flow at the surface.  L1 and the strong southerly flow ahead of it don't look at that disruptive, but combined with warming due to condensation in the precipitation system accompanying them (not shown), they serve as the proverbial straw that break's the camel's back.  By 0900 UTC 19 November (2 AM MST Tuesday), L1 has weakened, ...

Along with graupel, sastrugi is one of my favorite weather-related words and I saw plenty of it ski touring yesterday.   Sastrugi is defined by avalanche.org as "heavily wind eroded snow with wavy textures." Sometimes it looks rough or pockety.  In the photo below, it appears there is avalanche debris on this slope, but in reality it is all sastrugi.   In some areas, the sastrugi was dense wind board and generally supportive of a skier.  In others, it was actually somewhat soft and didn't ski to bad on the descent. Each turn was a mystery! Although I like sastrugi as a word, it's not my favorite snow surface to ski.  We can blame the sastrugi in this case on the multiday easterly wind event that has been affecting the Wasatch Range and Front since Thursday.  Observations from Alta's Mt. Baldy show the winds veering (turning clockwise) from southwesterly just prior to 1200 MCT 12 March (Tuesday) to north by 0000 MDT 14 March and then locking in wi...

A weak short-wave trough and moisture surge moving into northern Utah later today will bring cooler temperatures and a threat of a few showers and thunderstorms tomorrow.  The likelihood increases through tomorrow with isolated T-storms later today, scattered tonight, and showers likely tomorrow.   The NAM forecast valid at 1500 UTC (9 AM MDT) tomorrow morning shows the short wave trough and associated clouds and precipitation over central Utah. This isn't a major monsoon surge, so it won't be a drought buster, event if you happen to get a good downpour wherever you are.  The concerning part of the cool down is that while we will get some precipitation, there will also be dry thunderstorms, which are thunderstorms that produce lightning, but little to no precipitation.  Enjoy the modest cool down, but hope that we don't see many if any fire starts.   The extended model forecasts are putting an enormous ridge over the Pacific Northwest and southwest Can...

A high-amplitude upper-level ridge remains parked over western North America, but as shown in yesterday afternoon's 0000 UTC 23 Sep 500-mb height analysis, there is a potential fly in the ointment for Utah weather. Source: NOAA/ESRL The fly is the weak closed low that is sitting over the coast of Washington, which results from a weather feature that meteorologists call a coherent tropopause disturbance , or CTD.  A CTD is a localized cyclonic vortex, which is associated with counterclockwise rotation in the Northern Hemisphere and is strongest at the tropopause.  The tropopause separates the stratosphere from the troposphere. Source: NASA The CTD and closed low move into Nevada by tomorrow morning [1200 UTC (0600 MDT) 24 September]. A different perspective at this time is provided below by a 3-D colored representation of the tropopause, with cool colors indicating a lower tropopause and warm colors indicating a higher tropopause.  Note how the tropopause ...