In Brief:
Calm dry weather into the New Year.
Friday update:
I'm enjoying a quiet holiday week, and so is the weather. Figure 3 update shows that temperatures won't vary much over the next week, and there is basically no chance of precipitation.
New Year's Eve 11:59pm forecast:
Temperatures: 26F, calm winds, clear skies. Nice!
End Friday update.
Christmas Eve Update:
Longmont really got skipped this storm. I predicted 1-3 inches (0-2" in Firestone). Figure 2 update shows we got a trace to a quarter inch of snow (a coating).
Boulder did better with 1-3 inches. So, no White Christmas for Longmont this year.
Christmas Day Forecast for Longmont:
We'll have mostly clear skies in the day with a high of 38F and a low of 25F. Winds will be out of the west at 5mph.
End Christmas Eve update.
Saturday Update:
This isn't shaping up to be a very big or very cold storm at all. Some folks will get a dusting to a few inches in time for Christmas. Timing is for some rain showers later in the day (temps may get to the 50's briefly) then snow overnight to Christmas Eve morning.
Snowfall Roundup for Longmont:
GFS 1-3"
NAM Trace-2"
Weatherunderground.com Tr-1"
Canadian 3-5"
Weather5280 1-3" (Figure 1 update)
Channel 7 2.6"
Channel 9 1-3"
My forecast: 1-3" is most likely
End Saturday update.
The Forecast Discussion:
We continue around 20 degrees above normal for now, but changes come Christmas Eve Eve (Saturday) with a Pacific cold front (Figure 1). A storm system from the southwest will almost merge with a system coming in from the Pacific northwest (Figure 2 -curvy red line). They are not expected to work well together so the moist system will not get the cold air from the cold system to create a good snow storm.
Downslope flow (air coming from the west and dropping off the Rockies) may eat into snow totals along I-25 and eastward north of Denver up to Cheyenne (Figure 3). Most places may see a coating to a few inches of snow on Christmas Eve, according to the GFS.
The North American model (Figure 4) has a bit more snow. The Canadian (not shown) thinks the systems will merge well and give us 4-8 inches of snow. It is an outlier right now. The forecasters at weather5280.com (go read their stuff too!!) give I-25 folks north of Denver 1-2 inches and the mountains good totals.
I'll post an update with the Snowfall Round-Up in the next day or so. And a Christmas morning forecast. Come on back (but check out the Longer Range Forecast below first...).
The Longer Range Forecast:
After this system, not much more snow falls in the next 10 days (Figure 6). Temperatures return to about 10 degrees above normal (Figure 1). In the long range models, there is a hint of a snowstorm around January 2-4th (not shown). Come on back for updates!
