Hello all, so far no change to the temp part of my forecast that I put out yesterday for this week. In this post, I am going to concentrate right now on the snow totals because I am starting to see some bigger snow total potential in 2 of the computer models. Just not sure how much I am buying into it at this time due to the nature of these very cold air masses. Typically they dont produce big totals. Dont tell that to the Canadian GEM model and the ECMWF model. In some areas, both are showing some big totals. Both models are basing this on a 10:1 snow to liquid ratio, meaning that if the temp was hanging around the upper 20s to low 30s, one inch of liquid moisture would produce 10 inches of snow. As it stands right now, because of this very cold air mass, the ratio could be more in the 15:1 or even 20:1 inch range. One model is even going higher than that ratio (30:1), but right now I am not going with more than 20:1 which is 20 inches of snow per 1 inch of liquid precipitation. Maybe its because I dont trust just how cold we are going to get, and I need to see this continued consistency in forecasting the brutally cold air. If it does indeed get colder than my forecast highs, then I will definitely buy into the 30:1 (30 inches of snow per 1 inch of liquid moisture) or even higher With that bit of math explanation out of the way, here is what I am seeing right now in the 3 maps that I have uploaded. The first map is the ECMWF model, and it is really up there in Boulder and Larimer Counties, with a bit less in Denver Metro but still nice size totals. For example, Estes would be in the 12 to 16 inch range between Monday and next Sunday. Lyons and Boulder would be in the 6 to 12 inch range. Denver Metro would be in the 5 to 7 inch range. Of course this is if all the liquid moisture becomes available. What makes this interesting is that this is based on a 10:1 ratio which means these totals would be even bigger, thanks to the frigid arctic air mass. The second map is the Canadian GEM model snowfall output. It is showing 14 to 18 in the Estes area, 6 to 14 in the Boulder/Denver areas and 2 to 6 in Denver. Again, this is based on a 10:1 ratio which just like the ECM, these totals would be higher if it snows while the temp is in the teens to low 20s (or even colder). And the last map (number 3) is the liquid output from the WPC model. It shows a general .25 to .50 across the entire forecast area. At 10:1, this would translate into a general 2 to 5 inch snowfall, with the Foothills being in the 5 inch range. And the WPC liquid totals translation to snow would be higher if the highs stay in the teens to low 20s (or colder). OK, enough with the math equations. I think you all get the idea. Suffice to say the above snow totals in the ECM and the Canadian GEM will be higher if the high temperatures stay in the teens or colder. The first shot of snow will be with the arctic intrusion during the day on Monday, with disturbances triggering more snow throughout the next week. Here is my thinking for the next 7 days, as we are going to get several shots of snow. And this includes other computer models and QPF output that I have not listed here: Foothill locations (Estes, Nederland and Pinwood Springs): Expect 3 to 11 inches, where the 11 inches would be above 8,500 feet. Most Foothill locations below 8,000 feet should be in the 3 to 8. I have to have a big range here due to the elevations I am covering from Estes to Nederland to Pinewood Springs. Front Range (Lyons to Boulder, extending through the Denver Metro area and then moving north to the Wyoming border. All towns along and adjacent to this line are included. Just to name a few towns: Longmont, Loveland, Berthoud, Fort Collins, Windsor, Greeley, Firestone, Wellington and Johnstown. If your town is close to these towns, then they are included. Just not enough space to mention all the towns.). For this entire Front Range area, I am calling for 2 to 6 inches over the next week (between Monday and Sunday). I left out the GFS model output at this time because I missed the 12Z run. Ill see what the 0Z run has tonight. Earlier GFS runs were nowhere near the GEM or ECM so right now I see that model as the outlier model, meaning I am putting little stock into its output at this time. The NAM model has been much drier too. I will though see what it has to offer in the 0Z run this evening. As I mentioned yesterday, I will probably be toying with these totals once I see how this system is going to set up. Based on how the two longer range models are handling this, I think I am being rather conservative. I feel good about my forecast at this time. Hopefully Ill still feel that way after I go through the latest computer model runs a bit later this evening. For the rest of the country, as soon as I feel I have a good grasp of my Colorado forecast, Ill start talking about the rest of the country. I will be co-hosting a weather show on internet radio on Monday evening. As soon as I know that time, Ill be sure and let you all know how to tune in and what time Ill be on air. The show originates out of Connecticut. I may become a regular on this show. Ill know more after our first few shows. Stay tuned everyone. The Big Chill is on the way!
Posted on: Mon, 10 Nov 2014 03:04:57 +0000
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