Problematic Forecast Below 7500 Feet

Thursday, Thursday night and Very early Friday morning there is a huge bust potential for snowfall. This storm once again isn’t just one storm, there is a tremendous amount of subtropical moisture that will be streaming into New Mexico. There is currently cold air in place throughout the region.

Below see the snapshot of the region at 5 pm today. The dark green indicates heavy rain spreading into SW New Mexico. On the Utah/Arizona border in NE Arizona, you can see a low-pressure system has developed.  The models are really struggling with how far north that moisture will come and when. The best-case scenario for snow lovers would be for the New Mexico system to slow down and keep the warmer air at bay, while still providing enough moisture to collide with our colder air without modifying it. At this time I expect only snow above 8,000 feet, so if that is you, you should be in for quite a storm(s).

euroregional112606z.png

Sometimes in situations like this, the cold air could remain in some Valley locations and not quite scour out before the moisture arrives, it becomes a fight between the warm air and cold air, we don’t see that occur very often but it is common in Grand Junction and especially Gunnison. In the early stages, it is common for heavy snow to fall at first, but usually, the warm air wins and turns into rain or RSM (rain/snow mix). Other times the deeper valleys stay cold, all snow falls but above the valleys, rain mixes in (in what would be our mid-elevations between 7000-8000 feet).

So to recap we have three scenarios, and it may be a combination of the three at different times.

The closer the front gets the colder the air will get. Here is a look at Friday morning at 11 am. At this point, moderate snow should be falling down to 6,000 feet.

euro1126106zfri 11am.png

The other factor that has to be taken into consideration is that very heavy snow rates lower snow levels, so even though the models indicate a higher snow level that may not be the case.

If you are confused at the point, join the club, I am confused as well, as are any forecasters trying to predict the outcomes of this storm below 8,000 feet. The models vary run to run with snow levels, total accumulations and timing.

If you like to look at your NWS point forecast, expect it to vary a lot over the next couple of days while they try to figure this out.

Before I show the model runs, it is important to talk about model resolution, I like to explain resolution as margin of error. The models sample grid points to make a forecast. The larger the size of the grid, the lower the resolution.  The margin of error for the Canadian model is the greatest of all of the operational models at 9.3 miles. That is not a big deal in flat states but it is huge here. The GFS is next at 7.5 miles, The Euro is 5.5 miles. There are meso-scale models with higher resolution, but I just don’t have faith in them at the moment.

So we’ll start with the bad, the GFS is the warmest model here. And I will rip the bandaid off quickly.

 

GFS112712zsnow

GFS zoom

Screenshot 2019-11-27 at 10.51.01 AM

Screenshot 2019-11-24 at 10.41.07 AM

In case you were not aware, the 4.7″ you see there is at the airport.

You can compare the snow to the total liquid-equivalent precipitation.

Screenshot 2019-11-27 at 10.54.13 AM

Screenshot 2019-11-24 at 9.45.29 AM

Next up the Canadian

The Canadian is usually the most ambitious with its totals, sometimes it is like the Frankie McDonald of the models (if you don’t know who that is google him). I have seen the Canadian beat the Euro but it does not happen very much. The resolution is not that much lower than the GFS and it seems to do better in Colorado than other areas of the country where it is largely ignored.

cmc112712zsnow.png

Canadian zoom

Screenshot 2019-11-27 at 11.24.45 AM.png

Screenshot 2019-11-24 at 10.41.07 AM

And here is the Canadian liquid equivalent

Screenshot 2019-11-27 at 11.25.39 AM.png

Screenshot 2019-11-24 at 9.45.29 AM

Next up is the Euro model and its last two runs have been encouraging, because they have kept colder air in place, and while they still show some liquid mixing in occasionally tomorrow late morning and into the evening, below 7,400 feet or so, it looks like we will see a lull in the precip in the evening before the heavier snow comes in Friday morning. Here is the newest run.

euro112712zsnow

Euro zoom

Screenshot 2019-11-27 at 11.45.06 AM.png

Screenshot 2019-11-24 at 10.41.07 AM

 

Screenshot 2019-11-27 at 11.46.02 AM

Screenshot 2019-11-24 at 9.45.29 AM

As far as accumulations, I think Purgatory and Wolf Creek will get 30+ inches for the event. North La Plata Canyon is going to also get hammered with close to 24-30″ as well.

Since I am not sure about the snow level for tomorrow afternoon I will stick with the Euro through 11 am, it appears that it will be cold enough for snow until then in most areas.

Here is the Euro just through 11 am Thursday, tomorrow morning I will re-evaluate in the morning and try to get an update out early like I did this morning, then noon and late afternoon.

Screenshot 2019-11-27 at 12.12.02 PM

Screenshot 2019-11-24 at 10.41.07 AM

Here is the state view through 11 am Thursday

euro112712zthurs11snow

I will update again today after I digest the afternoon forecast discussion probably between 4-5 pm.

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