Snowstorm over, Boulder melting rapidly.

Our Spring snowstorm turned out to be mostly a dud in Boulder and Denver, at least as far as snow accumulation. Boulder received half a foot of wet snow for the entire storm. At elevations above 7000 feet, several feet of snow were recorded in some areas! Sporadic power outages have been occurred throughout the area due to heavy snow snapping tree limbs, which then fall onto powerlines. Boulder probably ended up with over an inch of rain equivalent moisture, and this should help alleviate the moderate drought we've been in for several months.

The National Weather Service is calling for additional accumulations this afternoon in Boulder, but that won't happen as temperatures are in the low 40's and only light rain is falling. From here on out, it's all Spring. Temperatures should reach 70 degrees later this week.

No additional snow accumulation today, but photos possible tomorrow.

With the surface temperature stuck at 35 degrees and only light wet snow falling, there will be no additional accumulation of snow in the Boulder area today. This includes grassy areas, not just paved surfaces. The National Weather Service's estimation of 8-12 inches for the daytime in Boulder is much too high. Upslope, above 7000 feet, some snow will continue to accumulate. Verne Carlson is reporting fourteen inches already up in Coal Creek Canyon!

As temperatures drop slightly tonight, I expect to see significant accumulation in Boulder between the hours of 8:00pm and 6:00am. Saturday's daytime temperatures might turn out to be too high to allow for any additional accumulation after the early morning hours. As I feared, slightly higher temperatures have turned this storm into a higher elevation storm. Boulder, Denver, and most of the urban corridor are thankfully receiving much needed moisture from this event, but little snow accumulation. This was a tough storm to call and the National Weather Service did a pretty good job, other than not updating their accumulation totals when necessitated by warm surface temperatures.

Heavy snow falling, but late to start and accumulate.

Our Spring snowstorm has finally materialized, but many hours late, as I predicted. Yesterday, light rain and a couple gropple storms covered much of the Boulder area. The rain did not turn to snow until about 6:00 this morning and this will reduce our snowfall totals. The very wet snow is also having trouble accumulating on the warm ground and has only reached about 1.5 inches in the last three hours on grassy areas. Roads are slushy, but not snow covered and not really slippery yet.

Last night, the National Weather Service reported snow falling in the foothills, accumulating to 2-9 inches. There was nothing on radar to indicate this, and I spoke with a couple friends (who live above 7000 feet) who said only light rain was falling. Perhaps one of the smaller valleys at higher altitudes was receiving snow, but this was certainly not representative of the Front Range foothills. In any case, the latest NWS forecast is still calling for up to two feet of snow for Boulder by Saturday evening. I think this will eventually turn out to be a significant snowstorm, but with a surface temperature just over 35 degrees, so far it's just slushfest '09. I think it's safe to say that NWS has over-estimated snowfall totals for this storm. I'll probaby start shooting this afternoon and I'll try to post some shots then.

Big snow on the way for the Boulder area.

Spring, which we had back in January, has left and been replaced with bi-monthly snowstorms. The GFS model is currently showing one inch of water in the atmosphere on Friday, which should be enough to give us ten to twelve inches of snow in Boulder by the end of the event on Saturday evening. The National Weather Service is indicating up to twenty inches of snow, but this is unlikely as Thursday evening's rain will probably not turn to snow as quickly as expected. I'm mostly basing this on climatological forecasting (it is mid-April, after all). The Denver area will likely see less snow than Boulder, as upslope forcing is more critically local for this event. In any case, this will be heavy, wet snow.

As I mentioned in my meteorology class today, this has been a tough storm to forecast. A slight shift of the low pressure center, or the advection of slightly warmer temperatures, will drastically decrease snowfall totals. Our forecasting ability, in this case, is limited not by model uncertainty or a lack of understanding of the atmospheric mechanisms, but more so by the chaotic nature of the atmosphere itself. Small changes close to the time of the event can result in large changes in precipitation for cities where orographic lifting is the primary lifting mechanism. In other words, welcome to life on the side of a mountain range.

More posts and photos to come on Friday.

Weekend of snow comes to an end.

A long weekend of heavy snow and blizzard conditions is finally tapering off. Several counties are still under winter weather advisories, but the low pressure cell that generated the snow has departed to the east. Snow fall totals in Boulder County ranged from five inches to eleven inches - a highly variable storm. No big wind here, but eastern Colorado has seen gusts over 50mph, leading to blizzard conditions. The city of Fort Collins had a power outage that affected 7000 people. The northern portion of Interstate 25 in Colorado and the eastern portion of I70 in Colorado were both closed yesterday, but reopened this morning.

This is the Foothills near the Flatirons Rock Formation in western Boulder.

Heavy snow in Boulder at 11:00pm.

Under a Winter Storm Warning, our light rain just turned to heavy snow at 11:00pm in Boulder. A Blizzard Warning is in effect for the eastern plains of Colorado, where winds could gust up to 50mph. Boulder will probably get a foot before the snow finally comes to end Saturday evening / Sunday morning. Should be good for a few shots, and I'll try to post some tomorrow.

(pseudo) Four Corners Low, Take Two!

Since a couple days ago, the GFS model has indicated another psuedo- Four Corners Low pressure cell smacking into Colorado in a nearly identical performance to the storm we had a week ago. This one is originating a little farther north, but the outcome will be very similar otherwise. Confidence is high and it looks like Saturday will be another 1-2 foot snowfall event along the Foothills of the Front Range. Like last week, snowfall rates could exceed 2 inches per hour and blizzard conditions are likely for much of eastern Colorado. I'll be chasing around the Metro area and will keep my blog updated with data and photos.