Memorial Day Weekend Looking Cloudy & Showery

I'm sorry to have to report that it appears increasingly likely that the upcoming extended holiday weekend is likely to feature an (over)-abundance of clouds accompanied by periods of showers and thunderstorms. A fairly typical mid-summer "monsoonal" pattern will set up over the desert southwest, sending plenty of moisture our way and keeping temperatures at slightly below normal levels.

While it won't be a total washout -- i.e., raining all the time -- mostly cloudy to overcast skies will prevail from Thursday all the way through Memorial Day Monday.

Downgrading Forecast: Expect 3-8"Temperatures Will Limit Accumulations

I have wrangled over this forecast for quite a lot of time now have decided to reluctantly downgrade yesterday's first call of 6-12" to 3-8". It's not that the moisture is not there, it's that I think ground and surface temperatures will allow for a lot of melting that the models are not necessarily picking up on. At the moment, the NWS is forecasting 5-10"; this is not a bad forecast, and they may very well end up being right, but I think lower amounts are more likely. Why?

First of all, the cold air is really lagging the moisture with this system; that means that we'll have quite a bit of "potential snow" that falls as rain at the onset. (Indeed the amount of rain we see before a changeover to snow may be the equivalent of 3-5" if there were more cold air in place and it had fallen as snow.) Also, temperatures soared all the way into the mid and upper 50s today with a decent amount of sunshine; the sun angle at this time of year is such that the ground is considerably warmer (even if the air temperature were exactly the same) than it was two months ago. While the bulk of the snow will fall overnight, which may mitigate these factors somewhat, I think that we may "lose" several inches of snow to melting.

Now, quite frankly, I hope that I'm wrong -- this ardent snow lover wants to see Mother Nature's bring as much as she possibly can our way -- but at the moment I think the NWS' forecast for 5-10 is a bit on the high side. That being said, the impact of almost all of the extenuating aforementioned factors (mostly the result of the fact that we're already into April) is very difficult to gauge; so, regrettably, my confidence in my forecast from 1 (lowest) to 10 (highest) is only about a 3 or a 4. It's definitely quite possible that the NWS' forecast for 5-10" ends up being right; hell, I wouldn't be shocked if a few isolated locations see up to a foot if this system really gets cranking and temperatures run a bit colder than we're currently expected.

Forecast for the greater DENVER METRO AREA is:

THREE to EIGHT inches

Expected timeline (+/- a few hours):

6pm - 10pm Friday:

• Scattered showers -- perhaps even a thunderstorm
• Temperatures dropping through the 40s

10pm Friday - 1am Saturday:

• Showers mixing with then changing to all snow by 1am
  
• Temperatures dropping into the mid 30s
• Little accumulation, especially on paved surfaces expected
  

1am - 6am Saturday:

• Moderate to heavy wet snow
• Gusty northerly winds 15-30mph (occasional gusts to 45mph)
• Temperatures drop to near 30
• 2-4" possible during this time
  

6am - 10am Saturday:

• Periods of light to moderate snow
• Gusty northerly winds 15-30mph (occasional gusts to 45mph)
• Temperatures drop to the mid to upper 20s
• 1-3" possible during this time
  

10am - 4pm Saturday:

• Snow decreases in coverage and intensity
• Continued gusty northerly winds 20-40mph
• Little additional accumulation expected after 3pm
• Temperatures holding in the mid to upper 20s

*Note: image above courtesy Accuweather.com

Major Spring Snowstorm This Weekend 6-12"+ and Near-Blizzard Conditions

I mentioned all the way back on Sunday the potential for a possibly major spring snowstorm this weekend. All signs now strongly point in that direction.

More than 6" and, perhaps, over a foot of wet snow is possible between midnight Friday and Saturday evening. The snow may be accompanied by near-blizzard/whiteout conditions at times, especially during the day Saturday, with north winds gusting up to 50mph at times.

I'll post a specific timeline and a more detailed accumulation forecast later today...

It's amazing to think that in a 10-day period from late March into early April, some places in central CO may end up seeing twice (!!) as much snow as they saw the ENTIRE winter season up until then.

Note: image above courtesy Accuweather.com

SNOW "Cancel"? Accumulating Snow Looking Unlikely...

A fast and dirty update to say that I believe that the possibility of (significant) accumulating snow for the greater Denver metro area still continues to diminish...

My current thinking:

• While there may be some light, periodic precipitation during the day Wednesday, it will likely fall as a rain/wet snow mix
  
• I'm expecting little to no appreciable accumulation in areas below 6000ft
• Wednesday night into Thursday still bares watching, as colder air filters in by then and moisture (aloft) may stick around. Even still, I'm now thinking that accumulation potential is only 1-3" Wednesday night...

Caveat Emptor: Unfortunately, this is still a (surprisingly) low confidence forecast. I could see some places in the Denver metro area seeing NO accumulating snow through early Thursday as easily as I could see other spots within the same (aforementioned region/time-frame) possibly picking up 3-5" -- primarily Wednesday night.

I'll keep you posted....

Surprisingly Complex/Low Confidence Forecast Is Accumulating Snow Still Possible Wednesday??

Despite my confidence earlier today, tomorrow's forecast has, since this morning, actually gotten a lot more complicated and less certain rather than the other way around -- a definite departure from the norm.

The computer models that I, and the meteorological community at large, rely on are in significant disagreement about a number of different, important factors over the next 36 hours: the speed of the approaching area of low pressure; the amount of upslope flow (northwest winds as opposed to northeast winds can make a WORLD of difference when you're talking mountain topography); and the timing of events.

What I do think is that (accumulating) snow is looking quite a bit less likely (at least for the daylight hours) tomorrow than I believed this morning. And, at this time of year, the sun angle is comparatively high meaning that snow falling during the daylight hours, especially when air temperatures are above freezing, is unlikely to stick to most paved surfaces -- therefore likely to be low impact.

The big question now is whether (as temperatures cool during the second half of the day tomorrow following the passage of a cold front) there's enough moisture remaining that we see accumulating snow Wednesday night into Thursday morning. One model says no way; another says yes and 4+ inches possible. I haven't decided yet which way I think things will progress but gut feeling is now (sorry, snow-lovers) saying the former -- accumulating snow chances significantly diminishing.

I'll try for another update during the first half of the day tomorrow, when some wet snow flakes may very well be falling, but are unlikely to stick to anything other than elevated and/or grassy surfaces.

A Snowy Start to April Now All But Assured 2-4"+ Snow Wed; Major Snowstorm this Weekend?

Folks, as I alluded to in Sunday's post, winter isn't ready to give up just yet. In fact, it's looking like the next 10 days to two weeks will feature significantly above normal snowfall courtesy an energized Pacific storm track and plenty of cold air in place -- especially for this time of year.

I'm increasingly confident about accumulating snow on Wednesday (probably in the 2-4" range, but this subject to change), and it still looks like a potentially major winter storm is possible this coming weekend. Looking further afield, I see even more potential snow threats next week.

Hold onto your hats!

More later...

Winter Telling Us It's Not Quite Over Several Chances for Snow Over Next Week

The next week looks to feature (well?) below normal temperatures for our region as well as a continued active Pacific storm track. I believe that there are at least 3 separate chances for snow in the Denver metro area over the next week.

The first (minor event):

• 50/50 chance for light snow tonight; up to an inch of accumulation

The second (possible event):

• Wednesday into Thursday when up to several inches may be possible

The third (possible event):

• This coming weekend the potential for a MAJOR snowstorm
• Confidence very low given how far away we are from this potential storm

So while Boulder is still recovering from nearly 18" of snow -- the same amount in a 24 hour period as had fallen the entire winter season up until then -- I believe there will be more accumulating snow for the area before Spring really takes hold.

(For those who are interested, Denver less than half (!) the amount of snow Boulder did because the upslope flow was not as strong there as it was right up against the foothills. DIA officially recorded 8.3" for the event versus Boulder's ~18".)