10/28/2009-10/29/2009 Winter Storm

[Tony Laubach]

Models are pointing to a chance for the first significant snowstorm across Colorado Wednesday and Thursday, including the I-25 urban corridor. As usual, the models are bouncing around possible solutions, but the strength of this system combined with a proper track could lead to a pretty hefty snowstorm for the area.

My biggest concerns right now are a more northerly track for the storm, bringing a brief shot at snow before dryslotting the Denver area as the system lifts northeast across Colorado into Kansas and Nebraska.

Even with a good track along the CO/NM border, the system should move east quickly, thus allowing for only a 24 to maybe 36 hour window of snow with burst of heavier snow.

The GFS paints nearly 2 inches of liquid is some places in eastern Colorado which could translate to over a foot of snow for lower elevations. Parts of the mountains could see a couple feet from this system.

Certainly worth watching for those on the backside of this very strong and dynamic system.

 

[Patrick Martin]

The potential for this system was enough to have me running up/down my 22ft extension ladder clearing leaves from gutters and downspouts Saturday afternoon.

The NWS Boulder office has issued a Winter Storm Watch for the Denver metro area, Palmer Divide, and foothills along the front range. Considering some of the model discrepancy, was suprised to see the watch issued this early, but with local media having started talking this up yesterday, probably a wise move. The afternoon AFD from Boulder highlights some of the hurdles this storm may have to overcome such as strength of the inverted trough along the I-25 corridor and the dry slotting that Tony mentioned. It will be most interesting in the next 24-36 hours to see how the track of this system evolves and the impact it will/will not have.

 

[Mark Blue]

You guys beat me to the punch here! Twelve years ago about this time of the year the weather turned really ugly here in Denver per the story on the Denver/Boulder NWS for October 25, 1997: http://www.crh.noaa.gov/bou/include/his.php?month=OCT&dayOfMonth=25

I certainly don't expect this storm to reach the proportions the blizzard of 1997 reached, but everything is so dependent on where the surface low sets up and eventually tracks as to whether Denver gets bombed or not. Thus far indications are this will be a snow storm that dumps 12" or so on the metro area, but that's more than enough to shut down a few businesses here in town. Hopefully where I work will be included as I could use an extra day off about now!

 

[Patrick Martin]

The Watches have now turned over to Winter Storm Warnings for the Colorado mountains, foothills, front range, and eastern plains.

Appears that models have now come into reasonable consensus that this system will track east from the 4 corners region into nrthrn NM/sthern CO, and then swing northeast into wstrn KS/NE. This track puts northeast CO into the bullseye for a medium duration snow event starting Tuesday night/Wednesday morning and lasting until late day Thursday. Accumulations of 1-2 feet in the mountains are likely, 10-18 inches along the Cheyenne Ridge/Palmer Divide, and 8-14 inches possible in the Denver metro area and eastern plains. Boulder NWS office highlights snow throughout the period, but with 2 intense periods of snow, the 1st coming in later Wed afternoon and the latter Thursday morning which should help to make the commutes at those times a complete mess. I'll be out and about to document and post pics by Friday.

 

[Tim Stoecklein]

Not sure I'm convinced you boys up north aren't going to stand a better chance than we are down here. I know the low is still a knuckleball at this point, but I think the mountains, and areas NE of Denver will pick up the bulk of this storm.

I'll be happy to be incorrect, however with all the corn barely touched on the eastern plains, I hope this thing hugs the front range as tight as possible.

 

[Jonathan Behle]

For what its worth.. This reminds me of 1997 only because that we had a major el nino going on then. We have el nino back again now too and yet another October snow system setting up.

 

[Tony Laubach]

NWS Boulder went ape-***** in their latest warning texts thinking Denver could see upwards of two feet. I think that's a bit on the hefty side at this point, but personally am going 10-18" for the metro with heavier amounts on the south and west sides. I bet my chief met that 14" inches would fall at Stapleton as he is concerned this dry slot will indeed scoot further west into the urban corridor.

More on my blog at http://www.tornadoeskick.com

 

[Allan Jeffers]

The cold wind just got here a short time ago. Some neat clouds rolled over too, but the light was fading fast and I could not keep shooting.

A short time after I got these, the rain started

 

[Jeff Lawson]

BOU just tweaked the Winter Storm Warning text, noting ongoing heavy snow in the foothills (with 2-5" already reported) and a specific mention of "up to 24 inches in the Denver area". I assume they're pushing the totals due to the early changeover.

The rain changed over to mostly snow about a half hour ago here in SW Littleton. Getting moderate, accumulating snow at the moment. Just need the winds to swing around a little more to the NE to really get things going...

 

[Mike Hollingshead]

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/00/images/nam_pcp_024m.gif

Use the 24hr 850 0c line on there.

Now notice the 36hrs of liquid equiv after that in western SD.

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/00/images/nam_p36_060m.gif

http://www.wxcaster2.com/CENTRAL_ETA_1000-500_SLPPRPTHK_54HR.gif

http://www.wxcaster2.com/CENTRAL_ETA_850_GPHTMPWINDRH_54HR.gif

SFC low beginning its bombing out. I'd say western SD is set for a blizzard chase. Hmmmm.

 

[Pat Darrow]

10/29/2009 NOW: CO

Didn't see this one started yet so thought I would. Snow has hit Colorado in ernest now. Here in northwest Colorado, moderate snow at this time with total accumulation of 3". Snowing at a rate of about 1" per hour. Temps in the mid 20's but little wind. Heavier bands moving moving up from the south. I'll let the front range gang chime in on the snow issues there.

EDIT: thread should be 10/28/2009. Mods, please change if possible.

 

[Tony Laubach]

Didn't see this one started yet so thought I would. Snow has hit Colorado in ernest now. Here in northwest Colorado, moderate snow at this time with total accumulation of 3". Snowing at a rate of about 1" per hour. Temps in the mid 20's but little wind. Heavier bands moving moving up from the south. I'll let the front range gang chime in on the snow issues there.

EDIT: thread should be 10/28/2009. Mods, please change if possible.

We have an ongoing discussion on this event in the Winter Weather section, so this can be merged with that.

 

[Patrick Martin]

Had 3-4 inches at my house on the grass/deck, and pavement was convered with 1-2 inches of slushy snow as of 5am in my neighborhood. Main roads and highways were predominantly wet north of Denver on my drive into work, although south of Downtown Denver where the heavier snow had already picked back up, I-25 was slushy and eventually became snow covered by the time I arrived to work at I-25 & I-225 shortly after 7am. Light to moderate snow continues to fall across all of the front range urban corridor and road conditions have deteriorated. Can still see some lane designation on the freeway from my office, but don't expect that to last long.

IMO the dry slot indicated on last nights NAM won't materialize and think the GFS advertised snowfall of 12-18 inches across the Denver metro area will verify.

 

[Mike Hollingshead]

GFS is going nuts with western SD to near central SD, slowing the rapidly deepening sfc low now.

http://204.2.104.196/gfs/CONUS_GFS0P5_SFC_12HR-ACCUM-SNOW_48HR.gif

7pm Thursday throuhh 7 a.m. Friday it lays down a foot in 12 hours.

http://204.2.104.196/gfs/CONUS_GFS0P5_SFC_ACCUM-SNOW_48HR.gif

Huge area of 18-20 inch. NAM a good deal less as it handles things differently. Great for trying to decide if a Thursday morning trip would be worth it or not.

http://www.rap.ucar.edu/weather/mod...sfc_mslp&hours=hr018hr024hr030hr036hr042hr048

 

[Robert Dewey]

Whipped up this graphic. Green isoline is GFS >12 inch snowfall, blue isoline is NAM >12 inch (storm totals). The shaded region is a rough average of the two.

Looking at cross sections, the best area appears to be between KPHP and KIEN. GFS storm totals in that area are on the order of 25-30 inches, while NAM is on the order of 18 inches. Convective instability is present around 700mb within the best DGZ / dendritic growth zone between 15z-18z THU and 3z-6z FRI. My guess would be a solid 12 inches within the majority of the shaded area... an embedded swath of 13-16, and isolated 18-20 inch amounts.

With that said, I'm going to say the "winner" will be between KPHP and KIEN at 20 inches.