Friday, April 3, 2009

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

Thursday, April 2, 2009

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

Wednesday, April 1, 2009

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....