Near-Record Heavy Snow to Plaster Colorado Accumulation: 7-14"; Isolated Areas See 2 Feet!

If you follow me on Twitter (@joshlarson) you know that I've been hinting at a major winter storm for our region since last Thursday...

All of the right ingredients appear to be coming together to produce a near-record fall snowstorm for the Front Range. We've got a deep trough (dip in the jet stream) of low pressure and abundant moisture to work with to produce HEAVY SNOW starting late Tuesday/early morning Wednesday and likely lasting well into the day Thursday.

I anticipate significant disruptions to transportation/travel with the likelihood of many cancelled/delayed flights in & out of DIA and the slight possibility that the airport may even shutdown entirely at some point -- though know I'm a better predictor of weather than airport closings. :)

My forecast:

**7-14 INCHES OF HEAVY SNOW**

*Isolated amounts of up to 2 FEET possible, especially north and west of Denver (i.e. Boulder, Fort Collins, Estes Park)

When all is said and done, this storm has the potential to become one of the most impressive October snowstorms in recent memory...

* Note: image above courtesy Accuweather.com

Record Cold Over the Next 48 HoursQuestion is: How Much Snow Falls?

The second Arctic front in as many days will push across the area early this evening, dropping temperatures from their afternoon highs in the 50s quickly to below freezing. With this front comes another opportunity for snow (yesterday's was a bust), and I have reason to believe that most places to the north of downtown Denver will indeed see accumulating snow.

Basically, the further north in Colorado (and closer to Wyoming) you go, the better chance for accumulating snow. So, Boulder has a better shot at seeing accumulating snow than Denver, and Fort Collins has a better shot than Boulder. Honestly, I have a gut feeling that this system will "over-perform" in that snow totals over the northern quarter of the state (including Boulder) will be higher than the National Weather Service's (NWS) current forecasts.

We'll see record lows in the teens (!!!) tonight (record low for this date at DEN is 25 degrees) along with a 70% of light snow -- possibly mixed with freezing drizzle at times.

"GUT FEELING" SNOWFALL ACCUMULATIONS:

• Denver: little or no accumulation (NWS predicting under 1")
• Boulder: 2-3" (NWS predicting under 1")
• Fort Collins: 3-5" (NWS predicting under 2-4")

**Note: Confidence on scale of 1-10 is only about a 4**

It's possible that a few left over snow showers or even pockets of freezing drizzle may linger into the day tomorrow, but the vast majority of any precipitation that falls will be Friday night. (And, note, I would not be shocked if downtown Denver ends up seeing no flakes at all; they may be just a little too far south this time around.)

We'll see record low temperatures again on Saturday; (the record low high temperature for the date in Denver is 34). I'm thinking it's quite possible temperatures won't make it out of the 20s for highs -- and at best may hit freezing (32). Also, we're highly likely to break records Saturday night, with bitterly cold overnight lows from 15-20 degrees (the record low temperature in Denver is 22).

From Sunday on out, however, we'll see moderating temperatures each day, with highs well into the 60s possible by mid next week. In fact, I think the entire rest of the month of October is likely to feature normal to above-normal temperatures. This cold bout is just a tease!

*Note: graphic above courtesy Accuweather.com

Arctic Front Blasts Through with Wet Snow High Temps Only in the 20s on Sat?!<

Though temperatures reached well into the 60s today in the Denver metro area, an Arctic cold front and associated area of low pressure will push through the region tomorrow. This will lead to temperatures 25-30 degrees colder than those on Wednesday, along with the first flakes of the season for locations below 7,000ft in the Denver metro area.

Because we saw a lot of sunshine on Wednesday, and temperatures were in the 60s, coupled with the fact that the cold front will come through the region Thursday morning as opposed to Wednesday night, I think that for locations below 6,500ft, snow will have a tough time sticking to most surfaces (perhaps even grassy ones) except during heavier bursts of snow. If snow lingers into the evening hours (questionable at this point), then I could certainly see the possibility for a quick 1-2" of snow to accumulate. However, at this point...

I think accumulations will probably be limited to around 1" on grassy & typically colder surfaces; a few spots could see closer to 2"

What I do know, however, is that that the mildest -- if you can call it that -- temperatures of the day will be during the morning hours Thursday (most likely in the low 40s), and that temperatures as the day wears on will drop to the low to mid 30s. It will be quite cold Thursday night, with overnight lows in the mid-to-upper 20s.

Another shot of re-enforcing cold air comes through the region Friday night into Saturday, which will deliver temperatures colder still: near-record cold temperatures may not make it out of the 20s for highs on Saturday with lows near 20. In addition, I expect a period of light snow from the overnight hours Friday into Saturday afternoon. It's a little too early to pin down accumulations, but amounts around 1" seem likely.

Sharply Colder Early Next Week! Some Wet Snow Possible Too?!

Though I anticipate a warm weekend (with temperatures as high as the low-to-mid 80s on Sunday), a strong dip in the jet stream and associated cold front (and area of low pressure) will come barreling through late Sunday or early Monday, dropping temperatures a good 25 degrees.

Both Monday and Tuesday we may not make it out of the 50s for highs. Of more interest, though, is that we stand the chance either night of frost even in downtown Denver. I expect low temperatures in the mid 30s both nights, and a freeze (first of the season) in the higher spots.

A cold rain is possible both days, too, and if central Colorado does indeed see precipitation, the snow level could drop as low as 6,000 to 6,500 feet. It's quite possible that locations at or above these levels could see wet snow (with potentially accumulating amounts above ~8,000ish ft.)

I'll update this as we get closer to Monday; until then, enjoy the mild weekend weather....

Note: image above courtesy Accuweather.com

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