Published Thursday 3/11/21 at 12:55 pm
As each day passes and the old GFS and new GFS continue to produce model runs with huge amounts of precipitation for Denver and the foothills, it occurs to me that this is the first major test of these models we have had.
To weather geeks like myself this is the equivalent of the Super Bowl, but for weather models. Whichever model(s) bust could lead to controversy. At the moment, the National Weather Service in Boulder is calling for 15 to 25 inches in the Denver Metro area with 24 to 48 inches for the foothills and high elevations east of the Continental divide.
This forecast for the metro area is more closely aligned with the Euro and Canadian model. The 24 to 48-inch forecast is closer to the GFS and GFS beta.
Here are the models’ snowfall forecasts for Denver Metro and foothills
Canadian
Euro
These two models are showing basically 20 to 25 inches in town versus the current Winter Storm Watch which is forecasting 15 to 25 inches.
But what if the GFS or new GFS is correct and this happens?
New GFS
Old GFS
If the old GFS is correct, 2/3 of the Metro area will get over 30 inches, and the foothills could get 60 to 80 inches. If the new GFS is correct the entire Denver Metro area will get 40 to 50 inches with similar amounts in the foothills.
So back to the controversy. What if the current forecast of 15 to 25 is the final forecast and 45 inches of snow falls in Downtown Denver? How many people will lose power? People are going to want to blame someone because that is the society that we have lived in over the last number of years.
Denver and CDOT are very well equipped, but no major city is good enough to stay up with 45 inches of snow in two days.
The snow is going to start in less than 48 hours and two models have double+ the amounts as the other models. That is not such a big deal when one model forecasts 5 inches and the other forecasts 10 inches. It is a huge deal when one has 20 inches and the other has 45 inches.
The last time I saw this much model discrepancy was Hurricane Harvey. The Euro was locked in for 5 days on the track and the total precipitation for days. It ended up being 100% correct. People were quick to dismiss the model before the storm when it was showing 40 inches of rain. After the storm, there were stories in the media about the “superiority” of the European model to the American models.
The new GFS, and to a lesser extent the old GFS, has been similarly dialed in for the last several days. If they are right and forecasters ignore them, or if one forecaster uses the new GFS and the NWS uses the Euro, it is going to be a big deal. To flip the coin, if they go all-in on the new GFS and the Euro turns out to be correct, people are going to accuse the forecasters of pushing a bunch of hype.
I wish that was what I was going through in our area, unfortunately, this is not going to be a big storm for us. Right now the models think Telluride is going to be the big winner for this event. I believe what they are seeing is some leftovers in the atmosphere from late Saturday through Sunday. These are a different type of leftovers in the form of moisture from the storm wrapping all of the way from the Colorado plains over to the western slope and falling in northwest flow from Telluride to Silverton and Ouray. The Euro is the most bullish in this scenario, next is the old GFS. The new GFS and Canadian are less bullish but still show the highest snow falling in the Northwest San Juans.
Here are the snowfall forecasts for our area through Monday morning.
Euro
Old GFS
New GFS
Canadian
Between now and Friday light snow showers will be possible in the higher elevations, but no significant accumulations are expected. Friday afternoon may even warm up slightly before the colder air comes in on Saturday.
A number of people emailed me yesterday about travel, in a lot of cases I told them to email me again on Friday. If you were one of those people make sure you email me back, because I received too many emails to remember everyone’s questions. It will probably be Friday afternoon after I post before I get back to you.
Next Update Friday afternoon, thanks for following and supporting the site!
Great job Jeff!