Monthly Archives: April 2015

Large uncertainty with coming storm

12:55 PM, Tuesday, April 14, 2015

A potent Pacific storm system moved onshore today and will be taking shape as it moves eastward into the Rocky Mountain region. The storm appears to be splitting. Some of our weather model guidance- particularly the reliable GFS model- has the northern part of the split storm becoming dominant and tracking into eastern Wyoming. This would put the heaviest precipitation north and east of Cheyenne, with minor amounts for the Colorado Front Range. However, a few model simulations from the GFS, along with the European and Canadian models, have the southern part of the split storm becoming dominant as it moves very slowly through the four corners region and northern New Mexico from late Wed through early Saturday.  That would put the heaviest precipitation in eastern Colorado and southeastern Wyoming.

This is a notable amount of uncertainty for a storm that is within 36 hours of starting. I’m a bit more inclined to trust the guidance in the wetter direction, but I am certainly not very confident. Whatever the outcome, Wednesday is likely to start mild and then turn cooler late in the day with some showery precipitation (rain in the lower elevations). It is likely to be windy at times both before and after the cold front.

Thursday is when the uncertainty starts to play out. The “minor precipitation” scenario would likely bring some unsettled showery weather Thursday, with drier & milder by Saturday.

The “big precip” scenario would likely see the main event late Thursday into Friday for the Colorado Front Range, maybe earlier in Cheyenne. Temperatures are likely to be marginal for snow below 6000 feet. I should point out that the wettest scenarios suggest multiple inches of liquid equivalent in and along the Front Range, and that would probably be mainly heavy snow in the mountains and possibly heavy wet snow in the lower elevations Thursday night.

I will update tomorrow. The storm will be completely inland so hopefully it will be better resolved by the observing network.

Significant change in weather later this week

12:45 PM, Monday, April 13, 2015

Weather nerds of the Front Range are excited about the possibility of a big storm later this week. As the storm system rolls in from the Pacific and moisture is drawn up from the Gulf of Mexico, there are some scenarios played out by weather models that would result in major rain/snow for some part of the Front Range region. But it’s not a done deal! There is a real possibility that the storm will  take on an orientation and track that either does not produce a big wet storm in Colorado/Wyoming, or is big only in a portion of the area.

Here’s what can be said confidently now: weather should become colder and more unsettled late Wednesday thru Friday. There is a chance this could evolve into a big storm. Stay tuned!

Cooler, little precipitation

5:45 AM, Wednesday, April 8, 2015

A Spring storm is moving through Colorado today and tonight, but the result should be only slightly cooler than average temperatures Thursday, and minor precipitation amounts late today or early Thursday,

The best chance for precipitation is in the mountains near the continental divide, but even there the snow accumulations should be minor.  For the Front Range urban corridor, there is a small chance for a few showers or a thundershower late Wednesday or Wednesday night, but some areas may get by with no measurable rain. Gusty west-northwest winds may develop along the Front Range for a brief period late Wednesday or Wednesday night.

Expect warmer weather to return Friday.

Cold, wet, and slushy, Thursday-Thursday night

4:30 AM, Wednesday, April 1, 2015

No fooling, the Front Range region is going to get some cold, wet weather between this evening and Friday morning. That will likely take the form of rain and then slushy snow, freezing into some icy areas by Friday morning. Some heavy snow is likely in the high elevations of the Front Range. Milder weather should return by the weekend.

The initial showers are likely to develop late today and this evening. Not everyone will get rain, but a few of us may hear the season’s first thunder.

Thursday and Thursday night should see a typical spring storm.  In the lower elevations the best chance for snow is during periods of heavier precipitation Thursday (the precipitation helps to cool the atmosphere) and Thursday night. The melting rate will be trying to keep pace with snowfall rate during the day. The precipitation is likely to orient itself in east-west bands of heavy precipitation late Thursday and Thursday evening, so the amounts may be quite variable over short distances. The lower elevations should see mainly wet roads on Thursday, but there may be local areas of accumulation on the roads during periods of heavy snow.  There is a better chance of accumulation on roads Thursday evening, and that should melt off by late Friday morning.

Accumulations:

Northeastern Denver suburbs, Weld County, Longmont, Colorado Springs: 3 inches or less

Cheyenne, Fort Collins, Boulder, Broomfield, Denver (and west/south suburbs): 3-6 inches

Nederland, Evergreen: 6-10 inches

Lesser amounts are expected in the western ranges, especially down in  the San Juans.

The proportion of the storm that will fall is snow is still uncertain. I will have little or no access to the internet for the next two days so i don’t know if I’ll update. But I don’t believe this will be a high-impact storm, just s slushy mess late Thursday or Thursday evening. We really do need the moisture!