COLORADO WEATHER by Josh Larson

Another snowstorm may be headed for Colorado; Cynics Watch, Wait

noreply@blogger.com (Josh Larson) — Sat, 13 Apr 2013 22:52:00 +0000

I'm quoted in a Denver Post article regarding our next shot at accumulating snow for early next week. Take a look!

Details to follow regarding snowfall potential...

MAJOR LATE-SEASON WINTER STORM & RECORD COLD

noreply@blogger.com (Josh Larson) — Mon, 08 Apr 2013 22:44:00 +0000

A major late-season snow storm coupled with record cold temperatures for this time of year will blast into the Denver metro area late Monday into Tuesday.

The result will be a widespread 6-12" of snow, with slightly higher amounts possible across the northern Denver suburbs (such as Loveland, Greeley, and Fort Collins.)

This will be a very dynamic system, with temperatures near 70 degrees Monday afternoon transitioning to (thunder?)-snow with temperatures crashing from 30s by mid-evening Monday to the teens by early morning Tuesday.

See more details including a freshly-minted "Bust Index" in the latest collaborative forecast from me (@ColoradoWx) and Brendan Heberton (@BrendansWeather) here!

FINAL FORECAST: 6-10"+ Across Denver Metro 3/22-3/23

noreply@blogger.com (Josh Larson) — Fri, 22 Mar 2013 22:58:00 +0000

I've been one of the most bullish outlets over the past few days and I'm sticking to my guns

Many/most outlets are predicting 3-6" for Denver out of this system; the NWS just issued an advisory for 4-8"; my forecast from yesterday for 6-10" with isolated higher amounts still holds. This will be an abnormally cold storm for late March across central Colorado, with temperatures in the low 20s during most of the storm. This will lead to snow:liquid ratios of near 15:1, which I think some other outlets are overlooking.

If my forecast ends up being wrong, I'll own it, especially as it differs fairly considerably from other outlets.

Please also check out my meteorological co-conspirator, Brendan Herberton's weather page here.

Stay warm (wind chills will be in the teens at times Saturday) and if you have to travel -- please be safe!

6-10" of SNOW for Denver Metro this Weekend!

noreply@blogger.com (Josh Larson) — Fri, 22 Mar 2013 00:56:00 +0000

I remain fairly confident that the necessary ingredients are coming together for 6-10" of snow to fall across the greater Denver metro area from Friday evening into late Saturday/early Sunday. I have have been more bullish than some of my meteorological cohort over the past few days and remain so. I think a combination of good dynamics with the system, much colder temperatures than the bust-like storm 2 weekends ago (hence higher snow:liquid ratios), and plenty of moisture will bring us these amounts, with slightly lower amounts over the northern suburbs.

Click here to see a collaborative forecast, along with some discussion of how my forecast varies from those of my meteorological co-conspirators, Brendan Herberton, Matt Makens and Chris Tomer.

Happy snow!

Biggest Storm of the Season?

noreply@blogger.com (Josh Larson) — Fri, 08 Mar 2013 22:40:00 +0000

Winter storm set to bring beneficial moisture to the Front Range

A good run of the models this morning has boosted confidence in the forecast for our winter storm due in late Friday night. Models are increasingly consistent in bringing a good dose of wet snow to the Denver metro area, and the chance for significant snowfall totals across the region. With that we are upping our snowfall forecast from this morning to 6 - 12 inches for Denver, but resisting the urge to go with the NWS forecast of 8 - 14” --- for now. Areas north of Denver may see more rain and therefore less snow.

Please view my collaborative forecast with @BrendansWeather here.

Largest Snowfall of The Season Thus Far to Hammer Denver

noreply@blogger.com (Josh Larson) — Sat, 23 Feb 2013 18:42:00 +0000

NWS Issues Winter Storm Watch Ahead of Rapidly Developing Storm

(This is a collaborative forecast by Josh Larson (@coloradowx) & Brendan Herberton (@Brendansweather)

11:30am Saturday: A winter storm headed for Colorado over the next 12 to 36 hours has the potential to bring significant snow to the Front Range urban corridor -- in fact, quite possibly, the heaviest snow so far this season. Model spread over the last 12 hours has been anywhere from about 4 inches in the city to over a foot. With that said, our snowfall forecast has been upped to 5 to 10 inches of snow for Denver, with the potential for higher totals, especially to our south and east. These numbers are subject to change as the day wears on, and given current trends, they could change up. Double digit snowfall totals certainly not out of the question, but let’s not get ahead of ourselves.

Snow is expected to start around midnight tonight, then become heavy at times through Sunday morning. Best chance for the heaviest snow, where rates could exceed an inch an hour, will be during the very early morning hours Sunday.

The other story we are monitoring with this system is the wind. A Blizzard Watch remains in effect for communities along the Palmer Divide, where sustained winds could cause poor visibility and dangerous driving conditions for a prolonged period of time. In Denver, wind will also cause blowing snow and at times poor visibility, especially during periods of heavier snow.

Snow should gradually diminish late in the day Sunday, before coming to an end Sunday night. In its wake, below normal temperatures will stay with us, and last through at least the middle of next week. With fresh snow cover, single digit lows are likely again by Monday/Tuesday.

This is a rapidly evolving situation that should be monitored closely as the day wears on. Expect updates as necessary over the next 12 to 36 hours, with any adjustments to snow totals and the latest winter weather advisories.

Up to Several Inches of Snow Possible Saturday Night across Denver metro!

noreply@blogger.com (Josh Larson) — Sat, 09 Feb 2013 03:34:00 +0000

CAVEAT: What I'm about to write absolutely pales in comparison to what's happening in the Northeastern United States, but this particular prognosticator is so snow-starved that I'm to the point where even the potential of a few inches of new snow gets me excited.

For the past several days, there's been an ongoing model battle as to whether or not central Colorado would see accumulating snowfall Satuday night into Sunday. There has been a lot of backing and forthing between models, but given the overall pattern, I have struggled to see how we couldn't see at least a couple of inches of snow during the time in question -- even as some models have literally printed out zero precipitation. (But given how many busts we've had so far this "winter," I have been hesitant to pull the trigger, especially in light of conflicting model data.)

However, the newest model data that has just come in suggests that 1-3" of snow is possible tomorrow night over the Denver metro area, with slightly higher amounts possible north and northeast of Denver (areas like my home in Greeley!). Based on what I'm seeing, I think amounts are more likely to bust "high" -- meaning higher than most outlets are currently calling for -- especially in the northeast quarter of the state (approaching the WY/NE border.)

In fact, the newest 0z NAM suggests that 2-3" of snow is possible in Denver and 3-4" is possible in Greeley. These numbers jive with some other, proprietary model data I have access to that suggests these totals are well within the range of possibility.

Rain or a rain/snow mix will develop over the Denver metro area over the mid-to-late afternoon hours and will quickly change to all snow by 6-8pm. This will be a short-duration event, with perhaps as few as 3-6 hours of snow, but some bands, depending on where they set up, can easily produce several inches out of the atmospheric dynamics available.

Further updates likely on Saturday as more model data comes in...

TO SNOW OR NOT TO SNOW? Low Confidence; High Bust Potential

noreply@blogger.com (Josh Larson) — Fri, 09 Nov 2012 06:07:00 +0000

I know we weather types tend to suggest that every storm in Colorado is a tough one to forecast -- and in many ways this is one of the nation's most topographically difficult locations -- but this possible weekend storm is driving this particular prognosticator crazy. The result is a decidedly low confidence, high bust-potential forecast whose wrinkles may not be sorted out for another 24 hours.

The setup: a deep trough of low pressure aloft and associated Arctic Cold front dive southeast into Denver metro during the day Saturday. Temperatures will plummet from near 50 early in the day to the low 20s by Sunday morning. The problem is models are having a ton of difficulty regarding 1) the direction of the winds in the lower and mid-levels of the atmosphere & 2) directly related, the extent to which precipitation may "make it over" the mountains. In short, they're having a problem resolving the extent to which upslope flow (and therefore snow) may or may not develop.

Early in the day we had a few models suggesting 1-3" (NAM), 3-6" (EURO), 6+ (GFS) for Denver, which is a wide spread in and of itself. Unfortunately, with this evening's model run, the NAM has adjusted to a scenario where literally no more than a coating of snow might fall (if that), while the GFS has also dropped precipitation amounts, but with some interesting geographic flies in the ointment. The latest run of the GFS would give ~4-6" to downtown Denver; with closer to 1-3" to the north, the exact opposite north-south orientation of previous model runs. (Note: for a primer on forecast models & their differences, head here.)

In the middle of these extremes are two fairly reliable global models (JMA and GEM) which have more or less cut the difference and suggested snowfall totals in the 2-6" area wide, with the outside chance for >6" in some geographically favored areas. The most recent model data from these models, however, is from this morning. (Newer model data will arrive overnight.)

Since even the forecast for Denver, let alone outer suburbs like Fort Collins or Greeley is a very challenging one at this point, I've neglected to mention the COPIOUS MOUNTAIN SNOWFALL poised to come gang busters to western Mountains. Please visit this outside excellent resource, Colorado Open Snow, run by fellow meteorological co-conspirator Joel Gratz.

In the meantime, where does that leave us forecast-wise for the greater Denver metro area? The bottom line is that after another mild day well into the 60s on Friday, rain showers may (60% chance) develop by mid-day Saturday as temperatures fall from near 50 to the low 30s by early evening and precipitation transitions over to wet snow. Thereafter, the expectation is for a 50/50 chance for snow showers through the duration of the overnight hours into Sunday morning as temperatures slowly fall to near 20 by Sunday AM.

Forecast Confidence (Scale of 1-5): 1.5 snow flakes

Snowfall Probabilities:

>1" -- 70%
>2" -- 50%
>5" -- 30%
6" or more -- 10%

Note, as more model data comes in later tonight into tomorrow morning, we should get a much better idea of how this evolving storm system may play out. It is highly likely that in later updates we may update snowfall totals either upwards or downwards. My gut feeling is that the models that tend to be slightly more accurate are painting higher snowfall potential than the typically less consistent /accurate models, which are now casting doubt on any accumulating snow fall.

In other words, when you wake up Sunday AM, you may have NO SNOW whatsoever on the ground, or a significant dump of over 6". Ain't Colorado great?

We'll keep you posted as more forecast model data comes in and the forecast evolves along with it.

Thanks for playing along!

Forecast vs Average Temperatures Oct 2-11

noreply@blogger.com (Josh Larson) — Tue, 02 Oct 2012 15:35:00 +0000

Here's a comparison between forecast and average temperatures over the next 10 days for Denver; note the probable frost/freeze later this week...

OCTOBER OUTLOOK: Trick or Treat?

noreply@blogger.com (Josh Larson) — Mon, 01 Oct 2012 18:14:00 +0000

October is very much a transitional month weather wise in Colorado. We can, and regularly do, experience three seasons worth of weather in one month: summer, fall, and winter. Those who have lived here long enough know that the weather often changes on a dime: 80s one day, with a frost or freeze, or sometimes even snow, a day or two later. Here I'll endeavor to paint a picture of how we might expect our weather to behave over the month of October this year. I'll primarily be looking at past years that featured similar overall atmospheric conditions to those we're experiencing now to predict what we might expect; this is called looking at analogues

We've seen predominately hot and dry conditions since May, with the most 90° degree days (total and consecutive) on record; the most days above 95°, and the most 100° degree days on record. All that heat was accompanied by little in the way of regular moisture. In fact, most of the state of Colorado is experiencing moderate to severe drought conditions at present. That said, there are reasons to believe this pattern is in the process of breaking down and that October has the potential to feature periods of colder-than-normal conditions and the potential for accumulating snow earlier than usual.

In making longer term outlooks, meteorologists look at many different overall atmospheric patterns and oscillations to provide guidance as to the major factors influencing the 'big picture' meteorologically. Right now we are experiencing weak El Nino conditions, which are expected to persist through the winter. We are also currently in the negative phase of the Pacific Decadal Oscillation (which functions a bit like the El Nino/La Nina cycle, but on a larger time frame), and we're currently in the positive phase of the Atlantic Multidecadal Oscillation. What does all that mean? It is constructive to go back and look at previous Octobers that featured these same overall conditions. The closest match happens to be quite recent -- October of 2009; there are other years that match up as well, though not as closely as 2009: these include 1951, 1957, 1963, 1965, 1968, 1972, 1976, and 2002.

The Climate Prediction Center (part of the National Weather Service) that produces longer-range outlooks is very hesitant in forecasting cold in any of their outlooks unless there is strong evidence to suggest a high likelihood. I know this because I used to work there! Why? Persistence suggests that we've switched into a longer-term cycle where warmer than normal conditions occur more regularly and with more intensity than periods of cold. Nonetheless, and somewhat surprisingly, they have a large swatch of colder than normal predicted for the eastern half of the US, with Colorado (at least east of the Divide) in the "equal chances" category, which to suggests, to them, that there is not strong evidence one way or another to support a forecast for warmer or colder than normal conditions in our neck of the woods. Respectfully, I disagree...

The analogues paint a slightly different picture -- one with more cold across most of the country including Colorado. First we'll take a look at all of the Octobers that match (to varying degrees) the setup we're seeing right now. That would suggest that almost the entire country has the potential to see colder than normal conditions in October. If we look at the best matchup -- which is October 2009 -- we see a similar picture, though with the cold signal positioned almost directly on top of Colorado. What we take from this is that the analogue years are suggesting that the current atmospheric oscillations and patterns are conducive to widespread cold developing this October.

Meteorologists can consult analogues for longer term forecasts, but it is helpful, indeed necessary, to also consult model guidance that tries to predict how weather systems will develop and progress. At least for the first half of October, we're seeing a cold signal as well -- this from the Coupled Forecast System (CFS). This predicts colder then normal temperatures through at least the middle of the month for a broad swath of the eastern two-thirds of the country. This model has pretty good accuracy within the Week 1-2 period, so we can say with a fairly high degree of confidence that colder than normal temperatures are likely to develop. In addition, shorter-range models also show a sharp cold front sweeping through the center part of the country by late in the day 10/3; and medium-range models suggest that the cold air this system is bringing with it is likely to last at least a weeks. This colder regime is likely to bring an end to the growing season, with a widespread frost or freeze likely by the morning of 10/4. Note, some models are also suggestive of the possibility of our season's first snowfall in the October 7-14 period -- about a week earlier than normal.

When we put all of this together, I can say with fairly high confidence that the first half of the month is likely to feature below normal temperatures with near normal precipitation. Predicting what will happen during the second half of the month, since is further out, is a lower confidence proposition, but I think we can expect near or slightly-below normal temperatures with near normal precipitation. (There are some suggestions that the cold, relative to normals, may shift to the east and ease up somewhat over Colorado, though it's premature to predict this with any confidence.) Bottom line, though: I would be very surprised if we don't have at least one accumulating snowfall event before the month is up!

Finally -- some food for thought: Remember 2009, which I've said is the closest match to how the atmosphere happens to be behaving this year? That October saw a whopping 17.2" of snow in Denver, some 400% of our normal October tally of 4.2"! And, temperatures averaged a full 8° below normal -- super cold. (Interesting to note, and we'll tackle this a month from now, but that November also saw more than twice the normal amount of snowfall in Denver.) While I don't think this October will be as cold, or feature as much snow, as in 2009, the writing is on the wall regarding colder than normal conditions and increased possibilities for snow.

MAJOR, LATE-SEASON WINTER STORM BY WEEKEND

noreply@blogger.com (Josh Larson) — Thu, 12 Apr 2012 04:25:00 +0000

I'm becoming increasingly confident the ingredients may be coming together for a major, possibly disruptive, late-season winter storm this weekend. Best guess at this point is that moderate to heavy rain late Saturday changes to heavy wet snow on Sunday. Significant accumulations are possible.

Stay tuned...

Incredible Snow Statistics!

noreply@blogger.com (Josh Larson) — Tue, 07 Feb 2012 21:25:00 +0000

To put last week's incredible snow storm, as well as this season's unusual snowfall, into perspective, I asked my meteorological cohort, Brendan Heberton (@BrendansWeather) to do some number crunching.

Here are the very cool statistics he came up with:

Denver has seen 142% of average snowfall so far this season. We've recorded 50.3" so far this season, and on average we receive 35.3" through the entire month of February.
We could receive no snow between now and April and still be above average for the season!
We are at 85% of the entire seasonal average for snowfall in Denver right now, with two of our snowiest months to go!

Incidentally, last night's over-performing snow, which brought up to 4 or 5" in some spots like downtown Denver, only managed to bring 1" officially at DIA.

Next chance for accumulating snow -- though at least at this point, it doesn't look like a big deal -- would be late Saturday into Sunday of this coming weekend.

AM Update: Widespread 10-20" SNOWFALL

noreply@blogger.com (Josh Larson) — Thu, 02 Feb 2012 15:13:00 +0000

8:15am Thursday 2/2/12

Model data that has come in overnight does nothing to lessen confidence that this will be an extremely high impact, if not record-breaking, February snowfall. Crunching the most recent model data and bifurcating into a 4" forecast spread produces the following results:

DENVER: 15-19"
BROOMFIELD: 13-17"
FORT COLLINS: 9-13"

Showers of rain or wet snow will develop by late afternoon across much of the Denver metro area, with a rapid transition to all snow as temperatures drop below freezing. Snow will then continue, moderate to heavy in nature, all night Thursday and much of the day Friday, perhaps even lingering into the early morning hours on Saturday.

The bulk of the snow will probably fall during an 18-hour window from midnight Thursday through 6pm on Friday. During this time snowfall rates of 1"+ per hour are likely.

Note: the largest February snow event on record for Denver was a 14.1" storm during February of 1912. I think we have a 50/50 shot of breaking this record...

BREAKING: Upping Snowfall Totals forEntire Denver Metro area to 10-15"+

noreply@blogger.com (Josh Larson) — Thu, 02 Feb 2012 04:28:00 +0000

Updated: 9:40pm 2/1/12

Newest guidance suggests that the track of this upcoming storm, which had been somewhat uncertain earlier today, is going to move on a path that is nearly perfect for a disruptive and dangerous snowfall to plaster the entire Denver metro area.

I am, therefore, upping forecast totals for the duration of the storm event (late Thursday into early Saturday) to

10-15" ACROSS THE ENTIRE DENVER METRO AREA, WITH ISOLATED SPOTS UP TO 2 FEET...

Heaviest snowfall totals will be from downtown Denver and points east and northeast. As you head northwest away from Denver, snowfall totals will decrease somewhat. Fort Collins looks to receive more like 8-12" from this storm.

More updates to follow...

Significant Snowfall Likely Across Denver MetroMost Places Can Expect to See a Healthy 6-12"

noreply@blogger.com (Josh Larson) — Wed, 01 Feb 2012 23:48:00 +0000

There's been a lot of consternation from other forecast outlets about computer modeling making it difficult to pin down a forecast for this storm. I beg to differ. If you follow the trends, weighting the models that have been most consistent as well as the ones that are the best "initialized" -- i.e., what the model forecasts at Hour ZERO is as close to reality as observations suggest -- then it's relatively easy to come up with a forecast of decent confidence:

THE STRONGEST EVIDENCE NOW POINTS TO WIDESPREAD 6-12" OF SNOW ACROSS THE ENTIRE DENVER METRO AREA...

...with the highest totals to the east and northeast of downtown Denver. As you head northwest from Denver, totals will drop off somewhat. (Places like Fort Collins are likely to pick up more like 4-8".)

I'll have detailed forecast information, time line, Q&A, etc. in upcoming posts.

Significant Snowfall Thursday into Friday?

noreply@blogger.com (Josh Larson) — Tue, 31 Jan 2012 18:24:00 +0000

Newest model guidance is lending confidence to the fact that we'll see at least some snow late Thursday into Friday of this week, and is suggesting the potential for significant accumulations, especially in Denver and points south and east.

I now believe at least a few inches of accumulation are probable, with the potential of 6" or more certainly not out of the question.

Updates to follow...

Late Week Snow?

noreply@blogger.com (Josh Larson) — Mon, 30 Jan 2012 22:40:00 +0000

An early heads-up that several computer models are hinting at the possibility of an accumulating snowfall for central Colorado during the late Thursday through early Saturday time period late this week.

It's far too early to know with any confidence if it snows, whether it might be heavy or not, where highest amounts will be, and even if it will be an entirely-snow event. Temperatures may be marginal at the outset.

However, I have reason to believe that at least a few inches of snow are possible by this time Friday.

Stay tuned...

>4" More Snow Will Fall from 2 Events: Friday night/Sat & Sunday night/Mon

noreply@blogger.com (Josh Larson) — Fri, 02 Dec 2011 18:55:00 +0000

With cold air firmly entrenched over the entire region, two separate disturbances will push through the area over the next 3-4 days, providing two chances for light accumulations of snowfall.

The first event will take place from late Friday night into mid-day Saturday, with the likelihood for 1-3" of snow.

The second disturbance will probably bring 2-4" of snow late Sunday into mid-day Monday. Because of the bitterly cold temperatures associated with, particularly this second event, the atmosphere will be efficient at wringing a decent amount of snow out of only a little moisture.

Between these two events, I think most places stand a good chance of seeing more than 4" combined...

How Much Snow Do You Think Will Fall Thursday?

noreply@blogger.com (Josh Larson) — Thu, 01 Dec 2011 02:27:00 +0000

Just for fun, let me know how much snow will fall on Thursday in Denver?

Click here to take this survey

3-7" of Wind Whipped Snow Thursday Bitter Cold to Accompany and Set up Shop

noreply@blogger.com (Josh Larson) — Wed, 30 Nov 2011 17:27:00 +0000

We're looking at our first significant snow storm in about 3 weeks late tonight into Thursday, as temperatures drop 40+ degrees in 24 hours and wind chills by late in the day Thursday drop to the low single digits. In addition, periodic near-blizzard conditions may develop Thursday morning into the afternoon.

In addition, I have every indication that the next 10-14 days will feature much below normal temperatures across Colorado, and the potential for at least several different snow events; more snow appears likely this weekend, for instance.

I'll publish a detailed forecast later today for tomorrow's snow storm.

In the mean time, follow my latest updates here.

Another Significant Front Range Storm6-10" of Wind-Whipped Snow Likely

noreply@blogger.com (Josh Larson) — Tue, 01 Nov 2011 03:46:00 +0000

If you follow me on Twitter (@coloradowx or @joshlarson), the snow storm I've been advertising for several days now is nearly upon us. In many ways it will be fairly similar to last week's storm, falling almost exactly a week later and with fairly similar snow totals.

A couple main differences from last week's storm: 1) We're likely to see little in the way of distructive tree damage as most all of the leaves have now fallen and this will be a drier, lighter snow; 2) due to colder ground temperatures I expect snow from this storm will accumulate more readily on roads -- which was largely not the case last week, and will therefore make Wednesday morning's commute a rough one. 3) This system will feature more in the way of wind than last week's storm -- this will lead to reduced visibilities and the possibility of brief blizzard-like conditions, with wind gusts to 45mph possible at times.

I believe that the NWS is being a bit conservative in their current forecast for 4-8" and would not be surprised if they bump up their totals tomorrow. I believe that most places will see 6" or more inches of snow. MY FORECAST IS FOR 6-10" OF SNOW TO FALL FROM TUESDAY EVENING THROUGH WEDNESDAY MORNING across the Denver metro area including Boulder and Fort Collins.

I'll provide an updated forecast, along with more details and a storm time line by early afternoon on Tuesday.

Until then, stay tuned...

Significant Snowfall Likely Wednesday

noreply@blogger.com (Josh Larson) — Sun, 23 Oct 2011 19:04:00 +0000

1pm Sunday: The details for next week's snow storm are coming into clearer focus as we get closer and model consensus improves. I can say with high confidence that >4" of snow appears probable for the entire Denver metro area (including Boulder and Fort Collins.) Some models are even suggesting totals closer to 8 or 10", but I'm going to remain conservative for the time being.

A rain/snow mix is likely to develop late in the day Tuesday changing to all snow sometime after midnight. Moderate to heavy snow is likely much of the day Wednesday with high temperatures only in the low-to-mid 30s (after Monday's record highs near 80).

I'll have a full forecast with more details as we get closer...

Next Week's Snow Coming into Better Focus

noreply@blogger.com (Josh Larson) — Sat, 22 Oct 2011 17:50:00 +0000

11:50am Saturday: A quick update to say that several computer models are suggesting a high probability for >6" of snow to fall during the period from late Tuesday into early Thursday. While it's still too far out to say with high confidence whether this, indeed, will come to fruition -- as the storm's exact track is still uncertain, it is certainly in the realm of possibility. In fact, a couple models suggest that double digit snowfall totals might be possible...

More to follow...

Accumulating Snow More Likely Next Week Several Inches Possible Late Tue-Wed

noreply@blogger.com (Josh Larson) — Sat, 22 Oct 2011 01:36:00 +0000

My confidence has increased over the past 48 hours in regards to the probability for accumulating snow to fall during the late Tuesday to early Thursday time period next week.

At the moment it looks like rain or a rain/snow mix Tuesday night is likely to change to all snow by the early morning hours Wednesday, continuing throughout the day, with high temperatures in the low-to-mid 30s -- as a strong cold front and upper-level low conspire with surface high pressure to provide plenty of moisture and a supply of enough cold air.

Several inches of accumulation appears possible at this time, with areas from Denver northward more likely to pick up several inches or more than areas further south. This may be an instance where Fort Collins does better than Boulder or downtown Denver, at the latter two locations due better than locations further south, primarily due to the fact that cold air will spill into the region several hours earlier towards the Wyoming border than points further south.

Stay tuned to Coloradowx.com as I update and fine-tune my forecast during the weekend.

Season's First Snowfall Next Week? Models Suggest There's a Decent Chance

noreply@blogger.com (Josh Larson) — Thu, 20 Oct 2011 00:10:00 +0000

I am beginning to see the signs that a strong cold front and associated area of low pressure digging to our south may conspire to bring snowfall to central Colorado by the middle of next week. While confidence for an event a week out is low, the fact that several different computer models seem to support the chance for snowfall over the area warrants mention.

My gut feeling, based on the data I've analyzed thus far, is that we have a slightly greater than 50/50 chance at seeing snowfall sometime in the late Tuesday to early Thursday time period, with accumulations not out of the question.

I'll update as we get closer to the possible event...