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Mountain West Discussion


Chinook

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The GFS seems to have reduced the amount of precip on the high plains, and has much less than 1.5" to 2.0" for the Front Range cities (like 0.9").

The 12z ECMWF keeps the precip pretty high, and even for Cheyenne and Laramie, too.  I can't tell what the totals would be with the ECMWF , but it looks to stall longer and give us more snow than the GFS.

 

You might want to try using adblock plus on Firefox for the Wunderground.com. You could potentially "save prefs" to show model data on Wunderground wundermaps, although this may not help your situation.

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We have a winter storm watch now. It looks like the GFS is predicting a temperature profile that's a little above freezing for me, at 12z Saturday. It would be kind of nice if it was all snow at that point in time.

 

Denver-Boulder NWS discussion (3PM today)

 

FOR THE FORECAST WILL FOLLOW THEGFS...ECMWF AND SREF WHICH SHOW A SLOWER...STRONGER AND MORESOUTHERLY TRACK. THIS TRACK TAKES TO UPPER LEVEL LOW FROM THE 4CORNERS TO WESTERN KANSAS ON SATURDAY. IF THIS PATTERN HOLDSTRUE...EXPECT SNOW TO FORM OVER THE MOUNTAINS AND FAR NORTHERNCOLORADO FRIDAY NIGHT. THEN WIDESPREAD SNOW WILL MOVE ONTO THE FRONTRANGE AND EASTERN PLAINS SATURDAY MORNING. PRECIPITATION MAY BEGINAS RAIN ACROSS THE EASTERN PLAINS BUT WILL QUICKLY CHANGE OVER TOSNOW. SNOW WILL COME TO AN END SATURDAY NIGHT. IT WILL END EARLYALONG THE FRONT RANGE AND MAY LINGER AFTER MIDNIGHT ACROSS THEPLAINS.NORTHERLY WINDS WILL BECOME GUSTY OVER THE EASTERN PLAINS SATURDAYAFTERNOON AND EVENING WITH GUSTS TO 40 MPH POSSIBLE. THE GFS SHOWSSTRONGER WINDS AND IF THIS HOLDS TRUE WOULD NEED TO ISSUE A BLIZZARDWARNING FOR THE NORTHEAST PLAINS.

 

 

Lets see if the 4km NAM snow total is close to reality:

 

post-1182-0-78444400-1362696752_thumb.pn

 

 

 

 

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And from the same AFD, this must really lead to forecasters losing hair:

 

THE 09Z SREF MODEL MEMBERS WERE A GOOD INDICATION OF THE UNCERTAINTY
WITH THIS STORM. THE STORM TOTAL SNOW AMONG THE 23 MEMBERS RANGED
FROM 1 INCH TO 19 INCHES. THE MEAN WAS 8 INCHES. THERE WAS A LARGE
CLUSTER OF MEMBERS IN THE 2 TO 5 INCH RANGE...THEN AT THE 8 TO 10
INCH RANGE AND ALSO AT THE 17 TO 19 INCH RANGE.

 

So, "partly cloudy with a chance of blizzard." Ummmm.....

 

Interesting also that the SNE board discussion has had some stuff about how incredibly unreliable the SREF models have been this winter.
 

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And from the same AFD, this must really lead to forecasters losing hair:

 

THE 09Z SREF MODEL MEMBERS WERE A GOOD INDICATION OF THE UNCERTAINTY

WITH THIS STORM. THE STORM TOTAL SNOW AMONG THE 23 MEMBERS RANGED

FROM 1 INCH TO 19 INCHES. THE MEAN WAS 8 INCHES. THERE WAS A LARGE

CLUSTER OF MEMBERS IN THE 2 TO 5 INCH RANGE...THEN AT THE 8 TO 10

INCH RANGE AND ALSO AT THE 17 TO 19 INCH RANGE.

 

So, "partly cloudy with a chance of blizzard." Ummmm.....

 

Interesting also that the SNE board discussion has had some stuff about how incredibly unreliable the SREF models have been this winter.

 

Yes, the SREF's have been "****ting the bed" along with the NAM a lot lately, particularly with events involving significant cyclogenesis.

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Latest thoughts:

Fort Collins will have boundary layer temperatures near freezing. The latest models still have us at 32 to 34 for some significant height (over 100 ft above ground). There have been times in the past when the models have said something like this and the situation turned out to be nearly all snow, for a long time. The low-level flow from the north, once again, seems to say the storm will focus heavy precipitation on Denver and the Palmer Divide, and too much downsloping will occur at Fort Collins (due to the Cheyenne ridge.) Why can't I catch a break?  Flow from the north is common with all cold systems. The 500mb low is still pretty potent.

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Latest thoughts:

Fort Collins will have boundary layer temperatures near freezing. The latest models still have us at 32 to 34 for some significant height (over 100 ft above ground). There have been times in the past when the models have said something like this and the situation turned out to be nearly all snow, for a long time. The low-level flow from the north, once again, seems to say the storm will focus heavy precipitation on Denver and the Palmer Divide, and too much downsloping will occur at Fort Collins (due to the Cheyenne ridge.) Why can't I catch a break? Flow from the north is common with all cold systems. The 500mb low is still pretty potent.

This year it seems like there are many more opportunities for a blockbuster- that's for sure- but they all seem to accelerate as they pass our longitude, so E-NE winds are fleeting at best! Fortunately for me we are at the far northern tip of what becomes the Palmer Divide 30 miles south, so we have done pretty well with what we have. I'm now up around 32ish inches on the season which I think is close to normal (I'm guessing average for me is about 40 inches season-to-date).

Question: why is the GFS so consistent/persistent at putting a 1.5" bullseye right over Fort Morgan? Can't think of anything orographic of note there, but it is very persistent.

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We are at 25" (compared to 37" to 40") year to date.

 

forecast meteograms with precipitation amounts. Check out the low level jet at Cheyenne - 44 knot north wind.

 

Fort Collins

post-1182-0-80352700-1362769957_thumb.gi

 

 

 

Greeley

post-1182-0-80779800-1362769956_thumb.gi

 

 

 

Denver

post-1182-0-33004400-1362769957_thumb.gi

 

 

 

Cheyenne

post-1182-0-32140600-1362769956_thumb.gi

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we have 2-3" but really hard to tell... fighting melting a bit and also blowing around. For sure not the rates that would get us to 10-12" by 5 PM... we'll be lucky if we get 6. Radar looks great but you can't make a snow fort out of echoes. Was down in the southern part of Parker around 6500 ft an hour ago and they are much better off with probably 4".

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OK, I'm going to call this bust-o-rama. Just about over here with about 5 inches if you stretch it, really 4.5.  NWS PNSs outside of the foothills max out at 5.5 inches. Storm is moving out 2-4 hours earlier than expected after arriving a good 6 hours later than expected. The radar looked great much of the day, but who cares. Where the heck was the snow???

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2 (or more) days ago I said "too much downsloping off the Cheyenne Ridge." and boy was I ever right. Way too much downsloping from the north and not enough generation of new snow led to very low snow totals north of Denver. The pavement never even got very wet here.

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We are getting snow in Fort Collins. It started accumulating at 6:00 or a little later. It's surprising considering the warmer temperatures today.

 

I had previously thought that the models had this small section of snow predicted for -tomorrow-. However, a look at the models from this morning revealed that they were mainly on target.

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Pretty, even more so as compared with the wind-driven stuff we got on Saturday. Dang icy getting to work though, and highs are about 20 degrees below forecast.... brrrr... too many long walks to meetings across campus today in a thin fleece jacket.

The unique thing about Western snow in the springtime is the pre-shoveled nature of the snowstorms. :)

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Our area averaged slightly colder than normal this winter (DJF). Fort Collins was -0.6F. Checking the precipitation data, the values for precipitation are a mix of above and below normal. Since October 1st, however, the area has been below normal precipitation.

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