COLORADO WEATHER by Josh Larson

Meaningful Accumulating Snow Still 24 Hours Away But 5-10" Likely to Fall Late Saturday into Sunday

jlarson05@gmail.com (Josh Larson) — Fri, 13 Nov 2009 23:00:00 +0000

**Note: Updated at 9:30pm Friday, November 13; I've lowered forecast accumulation totals as new data has come in**

While some high altitude locations in the mountains to the west of Denver metro have already seen significant accumulating snow, and while we may well see some wet, "conversational"-type snow tonight for parts of the Denver metro area (especially western, foothill suburbs like Boulder), the meaningful accumulating snow will hold off until late afternoon Saturday.

Essentially, we have two separate waves in the atmosphere to content with over the next 72 hours. The first pushes through tonight into early tomorrow bringing a slushy inch or two -- accumulating primarily on non-paved surfaces. The second wave, both colder and wetter than its predecessor, will deliver moderate to heavy snow from some time after late afternoon Saturday through at least mid-day Sunday. It is this batch of snow that is likely to deliver a significant 5-10" to the Denver metro area.

TOTAL EXPECTED ACCUMULATION

(for Denver Metro Area)

FIVE TO TEN INCHES

So let's get on with the detailed forecast:

Tonight:

A bit of wet snow possible during the evening & overnight hours
Temperatures nearly steady around freezing
0-3" of slushy accumulation possible on colder, non-paved surfaces

Saturday:

Scattered rain/snow mix possible through mid-afternoon
No accumulation expected
Highs climb to mid-to-upper 30s
By late afternoon, temperatures fall and moderate snow may develop 3-7pm
Little accumulation expected until after sunset

Saturday night:

Overcast skies with periods of moderate-to-heavy snow
Temperatures drop into the mid-to-upper 20s
3-6" of snowfall accumulation likely (including on roads) by dawn

Sunday:

Overcast with periods of moderate-to-heavy snow, especially during the morning
Snowfall is likely to taper in intensity and coverage by the middle of the day
Another 2-4" of snowfall accumulation likely by late afternoon
Afternoon highs near 32

Sunday night:

Slight chance of scattered snow showers during the evening
Little or no additional accumulation expected
Cold overnight lows drop to the low 20s
Monday morning's commute could be ugly!

Extended outlook:

From this juncture, Monday through Wednesday look dry with temperatures moderating well into the mid-40s for highs with overnight lows primarily in the 20s

Note: Image above courtesy Accuweather.com

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

jlarson05@gmail.com (Josh Larson) — Tue, 27 Oct 2009 19:14:00 +0000

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?

jlarson05@gmail.com (Josh Larson) — Fri, 09 Oct 2009 23:40:00 +0000

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?!<

jlarson05@gmail.com (Josh Larson) — Thu, 08 Oct 2009 02:30:00 +0000

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?!

jlarson05@gmail.com (Josh Larson) — Sat, 19 Sep 2009 03:16:00 +0000

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

jlarson05@gmail.com (Josh Larson) — Tue, 19 May 2009 22:17:00 +0000

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

jlarson05@gmail.com (Josh Larson) — Fri, 03 Apr 2009 23:29:00 +0000

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

jlarson05@gmail.com (Josh Larson) — Thu, 02 Apr 2009 18:45:00 +0000

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...

jlarson05@gmail.com (Josh Larson) — Wed, 01 Apr 2009 13:00:00 +0000

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??

jlarson05@gmail.com (Josh Larson) — Wed, 01 Apr 2009 05:34:00 +0000

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?

jlarson05@gmail.com (Josh Larson) — Tue, 31 Mar 2009 13:40:00 +0000

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

jlarson05@gmail.com (Josh Larson) — Sun, 29 Mar 2009 20:40:00 +0000

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".)

Late-Season Storm To Realize Its Full Potential 8-14"+ of Wind-Whipped Snow to Plaster Region

jlarson05@gmail.com (Josh Larson) — Thu, 26 Mar 2009 04:19:00 +0000

Make no mistake, folks: this one is the real deal. "Winter" so far over much of Colorado (east of the Rockies) has more or less been -- with the exception of a couple short blasts of Arctic cold -- missing in action. Temperatures have been at above normal levels for more than two-thirds of the winter and most (non-mountain) locations have only seen between 30-40% the normal amount of snowfall -- the lowest this late in the season in decades.

Thursday's wind-whipped snow will change that in a heartbeat. It's clear to me that this storm system -- a vigorous, deep area of low pressure approaching from the north and west and tracking south of us (the ideal location for prolonged upslope flow) -- means business and is likely to produce...

8-14+" of snow over the greater Denver metro area

It is possible that some locations will see as much snow in the next 24 hours as they've seen all season thus far! I do believe some isolated spots, primarily northwest of Denver, and/or along the foothills, have a shot at up 20" of snow!

And this storm is not exactly going to keep a low profile:

Blizzard-like conditions are possible, especially from 8am to 4pm Thursday
We'll see sustained east to northeasterly winds of 20-30mph with occasional gusts, especially near the foothills, to near 50mph
Whiteout conditions may develop at times because of the aforementioned heavy snow coupled with high winds
With temperatures dropping throughout the course of the day Thursday (from the mid to upper 20s during the morning hours to the mid teens by nightfall) and high winds, wind chill temperatures may drop to near ZERO at times.
There will be significant ground and air transportation disruptions and I believe it's possible that Denver International Airport (now replete with a scary, larger-than-life blue horse) might shut down at some point
This storm system will also funnel in bitterly cold Arctic air from western Canada, and we may see temperatures in the single digits by Friday morning.

Finally, a word about snow/storm duration: I expect that snow will fall (with occasional breaks) from around 4am Thursday through 10pm in the evening (+/- a few hours).

Snow lovers: get out and ENJOY! (Those ready for spring....sorry, not quite yet. In fact, I think the weather from here on out until the end of the first week of April is likely to be active, stormy, and potentially quite snowy.) And to everyone on the roads Thursday: please slow down and allow lots of space between you and the car ahead of you as roads -- especially non-treated, secondary ones -- may be treacherous with low visibilities.

[Note: image above courtesy Accuweather.com]

6-12" of Wind-Whipped Snow Thursday Winds to 50mph, Windchills to Zero Possible

jlarson05@gmail.com (Josh Larson) — Wed, 25 Mar 2009 03:57:00 +0000

After digesting the most recent model guidance, I'm comfortable with my earlier first call of 6-12" in the general Denver metro area. It's still a little unclear where the highest amounts are likely to be, but if I'd have to guess it would probably be right up along the foothills as well as areas south and east of Denver around the Palmer Divide; (this is subject to change however).

Note that whiteout conditions are possible at times on Thursday with occasional wind gusts to near 50mph and wind chills to ZERO at times!

Here's how I see things unfolding...

Showers of rain and wet snow Wednesday evening change to all snow after midnight
Periods of moderate snow overnight with dropping temperatures
Several inches of snow possible by dawn Thursday
Moderate/heavy snow Thursday + falling temps to near 20 by late afternoon
Winds gusting to 50mph at times may create whiteout conditions
Significant accumulations during the daylight hours Thursday
Major ground and air travel disruptions are possible
Snow continues moderate to heavy into Thursday evening
Snow tapers off (generally) from NW to SE by around midnight
Bitterly cold temperatures in the single digits by dawn Friday

Once again, at this time I'm generally expecting 6-12" of snow across the greater Denver metro area. It's possible that some places may see a bit less than this and that others may see more , but 6-12" is my best hunch at the moment.

[[ Current forecast confidence on a scale of ONE (huh?!) to TEN (supremely confident) is a 6.75 ]]

I'll make sure to update the forecast/conditions Wednesday and especially during the day Thursday.

Major Thu/Fri Snowfall Increasingly Likely

jlarson05@gmail.com (Josh Larson) — Tue, 24 Mar 2009 16:36:00 +0000

I'm becoming increasingly confident of the potential for a significant, accumulating snowfall for the Denver metro area from mid-day Thursday through mid-day Friday.

Indications are that near-blizzard conditions may develop late Thursday into early Friday with the possibility of heavy, wind-whipped snow.

My first guess forecast accumulation potential is 6-12"

I'll continue to refine these numbers as we get closer to the event.

More later...

Monday/Tuesday "Blizzard" is a NO GO But it Will Snow Later in the Week!

jlarson05@gmail.com (Josh Larson) — Sun, 22 Mar 2009 17:30:00 +0000

I'm more than ready to give a no-go/abort/cancel for significant (any?!) accumulating snow during the Monday/Tuesday time frame that I was revved up about only 48 hours ago. Such is the -- bipolar -- nature of dynamic, developing western storm systems during spring time. Fickle is the word that immediately comes to mind.

That being said, and I understand peoples' (warranted) skepticism due to the fact that this Mon/Tue snow threat has all but vanished, it is becoming more and more apparent that another storm system will develop over central Rockies region by the end of the work week, bringing the likelihood of accumulating snow back into the picture.

Regardless of the exact details of how the weather unfolds this week, I promise you (risky, no?) that the Monday-Friday time period this week will, overall, feature well below normal temperatures along with near-certain accumulating snowfall...just not the way I initially envisioned it.

I'll keep you posted...

Monday Snow: Many Questions Still Remain

jlarson05@gmail.com (Josh Larson) — Sat, 21 Mar 2009 17:33:00 +0000

While I would like nothing more than to be able to issue a confident, clear-cut forecast for this upcoming Monday's snow event, it would be irresponsible of me to, simply because way too many questions still remain. This is, at present, a tough, low confidence forecast.

Why?

I believe that the computer modeling (there are numerous regional, national and global forecast models run multiple times per day) is having a tough time resolving how things will (atmospherically) unfold mainly because the atmospheric energy associated with the strong area of low pressure poised to push through the region Monday into Tuesday is still thousands of miles away -- out over the Pacific.

The most recent runs of the models (over the past 24 hours) have generally tended to point to a much less impactful storm situation than one that I envisioned as a possibility on Thursday. The problem is that a jog of 50 miles in the track of the area of low pressure could make the difference between Denver seeing 2" of snow or 14" of snow. At the moment, it appears that the forecast storm track will not be ideal for heavy snow in the Denver metro area, and that places that really get socked will be further north and west -- we're talking north of Fort Collins into Wyoming.

We're still 48+ hours away until we see any meaningful precipitation in the Denver metro area, so models may waffle back and forth (still) until they get a better handle on things, though. I'm confident that we'll see some snow on Monday (especially the latter part of the day) into Tuesday, but I'm quite a bit less enthused about the potential for heavy snow (i.e., double digit amounts) than I was a day or so back.

I'll keep you posted....

URGENT: Potential Blizzard Next Monday, Tuesday

jlarson05@gmail.com (Josh Larson) — Fri, 20 Mar 2009 02:00:00 +0000

You heard it here first: the chances for a serious dumping of snow next Monday and Tuesday are very real. A deep, and slow moving, area of low pressure will push from the West coast to the Intermountain region by early next week.

Rain changing to heavy wet snow, accompanied by fierce winds (>50mph) are possible Monday into Tuesday. Note that heavy wet snow combined with strong winds has the potential to be very damaging this time of year -- power outages, roof collapses, etc. So this has the potential to be a disruptive and/or destructive event.

The Denver metro area has the potential to see more snow with this one storm than we've had ALL SEASON thus far (~18").

**The most recent computer modeling suggests the possibility of 1-3 FEET of snow!!**

More to follow...

Is There Still (Any?!) Hope for Snow?!

jlarson05@gmail.com (Josh Larson) — Thu, 19 Mar 2009 05:42:00 +0000

Right now this "winter" -- the quotes are there for a very real (and depressingly so) reason -- is among the top ten warmest winters for Colorado (east of the Rockies/Foothills) in the past century! Significantly more disturbing, (at least for this particularly ardent snow fanatic), if the weather doesn't change DRASTICALLY over the next 2 weeks, this could go down as *the* least snowy winter season in over a century! OUCH :(

I won't hold my breath, since I've already done that (and been disappointed) about 1,100 different times already this "winter "-- to ZERO avail -- but there are some early indications that the period March 22-31 *may* finally (?!?!) bring colder than normal and potentially snowy weather to our region.

If we don't get at least another 6"+ of snow during the remainder of March in the Denver metro area, this will easily go down as one of, if not **the**, least snowy March's since records have been kept! *Sigh*

Keep hope alive. And I'll keep you posted....

Frigid With 3-7" Snow Through Tuesday AM Western Ski Areas Warmer (!) but See 1-2 Feet

jlarson05@gmail.com (Josh Larson) — Mon, 26 Jan 2009 02:55:00 +0000

It's been a very cold and snowy day for much of the Denver metro area -- especially places north and west of downtown Denver towards the foothills. At 8pm Sunday evening as I write this, I measure 1.6" of snow at home in downtown Boulder, CO with a current temperature of 13.5 degrees. Here's the forecast through the duration of the snow event:

Sunday night:
The theme for Sunday evening will be periods of light snow, especially for areas north and west of Denver, towards the foothills. Frigid temperatures will bottom out around 6-10 degrees. If your pipes are susceptible to freezing (as mine are) I'd suggest leaving the water running slightly overnight -- especially since it did not get out of the teens all day.

Monday:
Plan on overcast skies with periods of light to moderate snow, especially during the afternoon hours. It will be frigid with high temperatures only in the low to mid teens! I expect that the heaviest snow of the day will fall somewhere during the 12-8pm period.

Monday night:
Overcast skies and periods of light snow will linger, especially in areas north and west of Denver. It will be bitterly cold, with overnight lows near zero in most locations -- necessitating taking any precautionary measures to keep pipes from freezing; (I'll be keeping the cabinets under my sinks open, heat on, and water -- both hot and cold -- at a trickle overnight.) Any scattered snow showers or flurries should taper off before dawn on Tuesday.

TOTAL EXPECTED ACCUMULATION

(for Denver Metro Area)

THREE to SEVEN INCHES*

*As is typical with upslope snow events, the higher amounts will be in the northwest reaches of the Denver metro area and near the foothills (like Boulder). Amounts on the lower end of that range will fall in downtown Denver and the south and east suburbs (i.e., Littleton & Parker).

Note: the western ski resorts will really cash in over the next 36 hours. I'm expecting 1-2 feet during this time in Aspen, Breckenridge, Vail, and surrounding ski areas. But they luck out even more because we are currently under the influence of an Arctic high, where the coldest air lies at the lowest levels. That means that temperatures in the mountains will be some 15-20 degrees warmer than lower elevation/further east areas east of the foothills (Denver, included) over this same time period!

Will Winter Ever Return? If So, When? Or, Why Has it Been So Warm Recently?

jlarson05@gmail.com (Josh Larson) — Wed, 21 Jan 2009 04:05:00 +0000

With two thirds of January already having passed, we're +8.3 degrees above normal in temperatures so far this month in Denver; that may not sound like a huge deal, but it is several standard deviations away from "normal." It gets even more pronounced if you look at just the past 5 days, when our temperatures have averaged a staggering 18 degrees above normal. (To put this in perspective, if the same mild weather that we've seen over the first 2/3 of the month were to continue over the next 10 days, this month would end up as one of the warmest Januarys ever on record for our region.)

...Meanwhile, many areas along the eastern seaboard back through the Great Lakes have seen the coldest temperatures in over a decade over the past week. What gives?

I tell people that about 2/3 of the time when it's colder than normal in Colorado, it's warmer than normal over the eastern US and vice versa. That's because the jet stream consists of ridges and troughs. The former, in general, fosters warm, dry conditions while the latter usually fosters cooler and wetter conditions. Several factors of climate variability (which I won't get into here, but would be happy to explain if you leave a comment or email me) have basically kept a trough more or less locked in over the eastern US for much of the month so far, with a ridge over our area for this time.

So, will winter ever return for our area? The answer is yes, and perhaps sooner than some of you might like. Though we'll see 20+ degree above normal temperatures again Wednesday and Thursday -- in the mid 60s -- a strong cold front will push through the area by Friday into the weekend, finally establishing a trough over the western US; atmospheric indicators signal that below average temperatures will probably begin early this weekend and persist trough at least February 1st -- and perhaps laterl; more or less, 7-10+ days of below normal temperatures developing shortly. In fact, the latest run of one of the major computer models suggests that by late this month we may again see sub-zero temperatures in our area.

And some snow -- though how much remains to be seen at the moment -- is definitely likely accompany this developing much colder weather pattern. In fact, the first half of next week may be appreciably snowy; it's a bit too early to pin down the details, but a slow-moving area of low pressure probably will try to develop during the Monday-Wednesday time period. (See image at right.) In fact, I think it's likely (70% chance) that we'll see as much, if not more, snow in the greater Denver metro area during the last week of the month than we've seen up until then -- generally 3-6" depending on where you live.

Even with a dramatic switch to colder temperatures and snowier weather in the last week of January, it is still highly likely we'll finish the month with significantly above normal temperatures -- though perhaps near normal snowfall. But I have a feeling we may (more than?) make up for these amomalies in February -- a month which I have a gut feeling may very may well turn out colder and snowier than usual.

...And don't forget, our snowiest month is not until March!

Unexpected Snow!

jlarson05@gmail.com (Josh Larson) — Mon, 12 Jan 2009 06:30:00 +0000

Something that makes me unbelievably happy is "unexpected" snow, which we're likely to see during the overnight period Sunday into Monday.

A small, but sharp, area of low pressure (associated with a fast-moving cold front) that was not, at all, captured well on computer models, will swing through the area on Monday.

We can expect around 1-3" of snow with it (perhaps 4" or more in some isolated locations) and considerably colder temperatures than we've seen recently.

Enjoy!

Much Colder + Snowy on Saturday

jlarson05@gmail.com (Josh Larson) — Fri, 02 Jan 2009 23:18:00 +0000

A rather potent cold front and associated area of low pressure will push through central Colorado on Saturday, producing afternoon high temperatures some 30+ degrees colder than Friday's highs in the 60s.

Light snow will develop sometime during the late morning or early afternoon and last into the overnight period into Sunday.

Up to 4" of snow may fall. Details to come...

Snowflake "Maker" to Improve Forecasts

jlarson05@gmail.com (Josh Larson) — Fri, 19 Dec 2008 23:47:00 +0000

Take a look at this intriguing article from New Scientist.

Incidentially, it will turn sharply colder Friday night into through the weekend, with a little light snow (less than 1" accumulation) possible early Saturday morning.

Temperatures Saturday won't make it out of the teens, with lows Saturday night as low as -10. Highs Sunday will, again, only be in the teens, but Monday should warm up to near freezing, with a chance of another batch of light snow.

Quick Burst of Snow in Denver Metro

jlarson05@gmail.com (Josh Larson) — Thu, 18 Dec 2008 21:12:00 +0000

A nice band of snow associated with a frontal feature has allowed snow to develop NW of Denver. A brief period of moderate to heavy snow may bring a quick coating to an inch of snow in some spots.

Temperatures are below freezing, so careful on the evening rush!