First of all, let’s get to the latest advisory.
NORTHWEST SAN JUAN MOUNTAINS-SOUTHWEST SAN JUAN MOUNTAINS-
LA SAL AND ABAJO MOUNTAINS-
INCLUDING THE CITIES OF VAIL, CRESTED BUTTE, TAYLOR PARK, BUFORD,
TRAPPERS LAKE, TELLURIDE, OURAY, LAKE CITY, SILVERTON, AND RICO
941 AM MST SAT DEC 7 2019
…WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM MIDNIGHT
TONIGHT TO 9 AM MST MONDAY ABOVE 8500 FEET…
* WHAT…SNOW EXPECTED. TOTAL SNOW ACCUMULATIONS OF 6 TO 10
INCHES WITH LOCALLY HIGHER AMOUNTS UP TO 14 INCHES. EXPECT
LOWER AMOUNTS BELOW 8,500 FEET.
* WHERE…PORTIONS OF SOUTHEAST UTAH AND NORTHWEST, SOUTHWEST
AND WEST CENTRAL COLORADO.
* WHEN…FROM MIDNIGHT TONIGHT TO 9 AM MST MONDAY.
* IMPACTS…TRAVEL COULD BE VERY DIFFICULT.
I like it as written, it makes sense with what the models are forecasting and leaves some room for some surprises. I am still a bit leary of the snow levels to start the night, but tomorrow morning it looks like we will be ok for snow at or above 6,500′ from about sunrise on. I will get to accumulations a little later, but snow totals are going to be dependent on the amount of time the winds blow favorably before and during the storm for each area.
Overview
In case you missed what I wrote yesterday here is the set-up for tomorrow’s storm. “Another pacific storm will begin to come onshore this evening and start working its way into the Great Basin Saturday. This is a large system and a piece is going to go north and combine with a large longwave trough full of very cold air reaching from the east coast of the US to British Columbia. Another piece will go south, which will be the part of the system that begins to affect us Sunday morning. Late Sunday the northern trough will drop south pushing colder air into our area and flow will change from the SW to Northerly/Northwesterly shutting off the precipitation to most areas except those that prefer NNW flow.” Since I wrote this yesterday I have been seeing more westerly flow in the models.
Timing has not changed much in the models for the last 24 hours-which is surprising to me. It still looks like light precipitation will start falling late tonight mainly above 8,000′ between 11 pm and 2 am. Heavier precipitation will start between 5 am and 8 am, falling as snow mainly at or above 6,500′ accumulations will be difficult below 7,200 feet due to melting. If you wake up and it is completely dry out in the morning that probably means a delay more than a complete miss. If that is the case you can rest assured I have either written a post or am in the process of doing so to let you know the new timing. Different models are showing different temperatures by 4-5 degrees at the surface tomorrow morning at 5 am.
There are a lot of moving parts that will have to come together for any one area to get a lot of snow, the models have been trending up, I made a point of showing the NAM model yesterday with its push for higher snow totals in the areas that favor the northerly, northwesterly, and westerly flow. This could include higher elevations along as well as just north and south of 160 west of Durango. It definitely affects Telluride, Dolores County, and areas around Mancos Hill. That is why I said I liked the wording of the Advisory because it leaves room for upside surprises.
Here are three snowfall forecasts from 3 different models for your viewing pleasure, remember that these are not accumulations, they are snowfall before melting.
Euro
GFS
NAM HiRes zoom
All three have an interesting take but there are a lot of differences. Some people are going to be very happy and some are going to feel cheated. If the NAM HiRes above is correct, certain mid-elevation areas are going to be very happy! We will see.
If there is anything worth sharing later today I will update, otherwise I will have something out early tomorrow morning.
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