There is very good agreement among the models that light snow will move into the higher elevations on Tuesday from west to east and north to south as early as Tuesday mid-morning. Snow should pick up in the afternoon and spread into the mid-elevations before sunset. A brief rain or mix may start in the lower elevations before turning to snow before the heavy snow bands start moving through Tuesday night. Snow continues through Wednesday morning with periods of moderate snow. Models diverge after this with some models showing a lull only to have snow resume late Wednesday and Thursday. Some of the models show light snow continuing on and off through Thursday. While a couple others end things fairly abruptly on Wednesday afternoon. For that reason, the NWS has issued an advisory beginning Tuesday at noon ending Wednesday at noon for 5-10 inches above 8,500′ with the possibility of a foot or more in some locations. I think this is a great call. This is a very flexible issuance because they have stuck with advisory criteria which they could easily upgrade Tuesday night, don’t be surprised. Also, it’s only a 24-hour advisory so they can reassess overnight into Wednesday morning to account for how the new model runs deal with Thursday. I also wouldn’t be surprised to see another advisory issued for the middle elevations sometime tomorrow. Based on what I am seeing I am in more in the 8-14″ camp for Purgatory with 12-18″ for Wolf Creek, I also believe many areas will have snow lingering into Thursday. I think 2-5″ is a good bet for low elevations with 4-8″ for mid-elevations. 8-12″ will also be a possibility for areas around Upper Lemon as well as Mayday. This is not going to be a great storm for Telluride but you could sneak in a quick 4-8″ depending on how the storm wraps up Wednesday and Thursday.
Here are the latest model runs.
Euro last night
GFS yesterday afternoon
Last night’s GFS
And here is the Canadian, which by the way, finally yielded and is taking a further east track with the second storm.
Don’t get too excited over there in Cortez when you look at the Canadian model, its lower resolution affects model output there. So no, I really don’t think you will get 6.2 inches of snow.
Here is the advisory
SOUTHWEST SAN JUAN MOUNTAINS-
INCLUDING THE CITIES OF SILVERTON, RICO, AND HESPERUS
258 AM MST MON DEC 23 2019
…WINTER WEATHER ADVISORY IN EFFECT FROM NOON TUESDAY TO 6 PM
* WHAT…SNOW EXPECTED. TOTAL SNOW ACCUMULATIONS OF 5 TO 10 INCHES
WITH LOCALLY HIGHER AMOUNTS EXCEEDING A FOOT.
* WHERE…SOUTHWEST SAN JUAN MOUNTAINS INCLUDING RED MOUNTAIN,
MOLAS AND COAL BANK PASSES.
* WHEN…FROM NOON TUESDAY TO 6 PM MST WEDNESDAY.
We still have 24 hours of model runs before the advisory starts and that may lead to some changes, but overall things look really encouraging, it is nice to see the models come together on the bulk of the storm and it is also great to see increases in the totals as the onset of the storm approaches. I have some shopping to accomplish today but should have time to update this afternoon.