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Mountain West Discussion


Chinook

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Here's a thought I had. Astronomical summer is June 21-Sep. 22, and astronomical fall is Sep. 23 to Dec. 22.

 

We normally consider that meteorological summer is June 1 to Aug. 30, meteorological fall is Sep. 1 to Nov. 30.

 

What if we defined seasons as such: meteorological Summer is June 5 to Sep. 4, meteorological fall is Sep. 5 to Dec. 4 met. winter is Dec. 5 to Mar. 4, met. spring is Mar. 5 to June 4.

 

Then what is the half-way point of each meteorological season? July 20 is 45 days after June 5. Oct. 20 is 45 days after Sep. 5. Jan. 19 is 45 days after Dec. 5. Apr. 19 is 45 days after Mar. 5. This makes sense with most of the climate normals in the middle of the USA-- that is, July 20th is about the hottest day of the year, on average, and October 20th is about the mid-point of the decreasing temperatures of the fall. January 19 is about the coldest day of the year for areas in the Midwest and Northeast, and  April 19 is about the mid-point of the increasing temperatures of the spring.

 

(Note, the coldest day, on average, in Fort Collins is around December 21-25. Merry Christmas!)

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Nothing in Boulder proper but higher elevations saw their first snow; went to chatauqua and the peaks were covered. 

 

We got about 1" here in Estes, but it quickly melted away this morning and transient light showers ongoing today. Above the timberline in both RMNP and the Mummy Range appears to be filled in, finally.

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Looks like next shot is a week from now if the Euro is to believed; 3 consecutive runs with significant snowfalls, but still 7 days out,

Good catch, BoulderWx. As of today, the Euro and the GFS showing some QPF (probably snow) around or south of Denver for Tue-Wed.

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Good catch, BoulderWx. As of today, the Euro and the GFS showing some QPF (probably snow) around or south of Denver for Tue-Wed.

Thanks, both models still struggling with just how widespread the event will be as well as potential moisture associated with it; par for the course 5 days out, but nice to see a more active pattern. Euro was also advertising something around the Friday/Saturday timeframe but seemed to back away from that idea with its 12z Run on Friday afternoon

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0z GFS & Euro appear to keep the pattern active through the next 10-14 days with a few solid cold shots.  The Euro looks especially juicy for the system early-mid next week.  Hopefully we can build that snow pack early and often!

Yeah, just reviewed the models from last night, for the Boulder area, they currently portray the following:

GFS (06z): 1-3"

CMC (0z): 1-2"

Euro (0z): 3-5"

NAM (6z): 0-1" (more to the west and to the east)

 

I'd be happy with solid inch or two to get the season started; anything else will be a bonus

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Looks like a quick hitter snowstorm with some possibly some frontogenesis banding or sort-of-convective snowfall. If there is too much north wind, Fort Collins to Greeley might get too much dry air under the clouds. Certainly looks like a strong north wind. 700mb may be close to 0C at 00z Wednesday--  perhaps some areas will get a rain shower before snow.

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Question for anyone with more knowledge than myself. I'm noticing on several of the models, there seems to be a lack of qpf output around the boulder/denver metro, with significantly more precip on either side. 

 

I recently moved from the east coast, and the only time I would see those relatively large gaps of qpf was in miller b situations, where storms would skip to the coast, leaving an area 'dry slotted'.

 

It this something to do with the mountains, dry slotting the immediate areas to their east, or is it more of a function of the models depiction?

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Question for anyone with more knowledge than myself. I'm noticing on several of the models, there seems to be a lack of qpf output around the boulder/denver metro, with significantly more precip on either side. 

 

I recently moved from the east coast, and the only time I would see those relatively large gaps of qpf was in miller b situations, where storms would skip to the coast, leaving an area 'dry slotted'.

 

It this something to do with the mountains, dry slotting the immediate areas to their east, or is it more of a function of the models depiction?

Don't know if I have more knowledge but I have now 5+ years experience here, after moving from the East Coast myself. Unfortunately, we don't get the kind of excitement they do on the East Coast nearly as often, due to less moisture, less thermodynamics with the ocean and Gulf Stream, etc. We see the effect you mention a lot, both in modeling and in reality, though my general sense from reviewing, say, COCORaHS data is that the effect in reality is slightly less than with the models (i.e. we don't get shafted quite as much as models would indicate). I do think that downsloping/shadowing plus lower elevations both contribute to this effect. I live in the south metro area, near Centennial airport and about 400 feet higher than downtown, and we frequently get just a tad more than much of the metro area. Boulder tends to be a winner in snow situations recently, though.... proximity to upslope is better.

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Don't know if I have more knowledge but I have now 5+ years experience here, after moving from the East Coast myself. Unfortunately, we don't get the kind of excitement they do on the East Coast nearly as often, due to less moisture, less thermodynamics with the ocean and Gulf Stream, etc. We see the effect you mention a lot, both in modeling and in reality, though my general sense from reviewing, say, COCORaHS data is that the effect in reality is slightly less than with the models (i.e. we don't get shafted quite as much as models would indicate). I do think that downsloping/shadowing plus lower elevations both contribute to this effect. I live in the south metro area, near Centennial airport and about 400 feet higher than downtown, and we frequently get just a tad more than much of the metro area. Boulder tends to be a winner in snow situations recently, though.... proximity to upslope is better.

really appreciate you sharing the insights; something I'll be interested in observing throughout the winter.

 

also, I've heard what you described quite a bit; average slightly more snow, but comes more gradually opposed to the major storms we usually get back east. 

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Boulder, as of the NOWDATA web page on the NWS Denver/Boulder web page, gets 88.3" of snow per year. Denver/Stapleton is 53.8". Fort Collins, 55.8", Greeley, 40.8". The Denver metro area is known for getting 50" to 70" of snow per year, depending on the proximity to the foothills or the Palmer Divide. In my estimation, the Palmer Divide gets about 80" per year.

 

Our snow season lasts from October 1st to about May 10th. Boulder gets pounded with heavy snow at various times, over the course of these 222 days. The length of the snow season is long compared to the East Coast. Boulder gets the most snow in the months of November, December, and March. The nearby Flatiron Range, and the proximity to the Continental Divide (12000ft) makes Boulder a good location for extreme upslope lift.  Boulder is also a location of extreme downslope Chinook winds and warm temperatures from 60 to 70 on some days in the winter.

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NWS just issued a Blizzard Watch for much of NE Colorado. 

 

 

 

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
305 PM MST MON NOV 9 2015

...A FAST MOVING BUT POTENT STORM SYSTEM WILL MOVE ACROSS NORTH
CENTRAL AND NORTHEAST COLORADO TUESDAY NIGHT INTO WEDNESDAY
MORNING...

.A STRONG WINTER STORM WILL IMPACT COLORADO TUESDAY NIGHT THROUGH
WEDNESDAY MORNING. BY LATE TUESDAY NIGHT...THE STORM SYSTEM WILL
BE MOVING OVER EASTERN COLORADO AND UNDERGOING RAPID
INTENSIFICATION. RAIN SHOWERS ON THE PLAINS TUESDAY EVENING WILL
CHANGE TO SNOW OVERNIGHT. NORTH TO NORTHWEST WINDS WILL ALSO
INCREASE THROUGH THE NIGHT...BECOMING STRONG ENOUGH TO CAUSE
BLOWING AND DRIFTING SNOW LATE TUESDAY NIGHT THROUGH WEDNESDAY
MORNING. VISIBILITIES ON THE PLAINS WILL BE RESTRICTED BY THE
BLOWING AND DRIFTING SNOW. DRIVING CONDITIONS ON THE PLAINS COULD
BECOME DANGEROUS DUE TO THE WINTRY MIX OF WEATHER.

COZ035-038-100615-
/O.NEW.KBOU.BZ.A.0001.151111T0700Z-151111T1600Z/
LARIMER AND BOULDER COUNTIES BETWEEN 6000 AND 9000 FEET-
LARIMER COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY-
INCLUDING THE CITIES OF...ESTES PARK...GLENDEVEY...NEDERLAND...
RED FEATHER LAKES...FORT COLLINS...HEREFORD...LOVELAND...NUNN
305 PM MST MON NOV 9 2015

...BLIZZARD WATCH IN EFFECT FROM LATE TUESDAY NIGHT THROUGH
WEDNESDAY MORNING...

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A BLIZZARD
WATCH...WHICH IS IN EFFECT FROM LATE TUESDAY NIGHT THROUGH
WEDNESDAY MORNING.

* TIMING...PERIODS OF MODERATE TO HEAVY SNOW...COUPLED WITH STRONG
WINDS WILL DEVELOP LATE TUESDAY NIGHT AND CONTINUE THROUGH EARLY
WEDNESDAY MORNING.

* SNOW ACCUMULATIONS...4 TO 7 INCHES IN THE FOOTHILLS ABOVE 6500
FEET...WITH 2 TO 5 INCHES ELSEWHERE.

* WIND/VISIBILITY...NORTHWEST TO WEST WINDS 20 TO 30 MPH WITH
GUSTS TO 50 MPH WILL DEVELOP LATE TUESDAY NIGHT AND CONTINUE
THROUGH WEDNESDAY MORNING. AREAS OF BLOWING SNOW WILL REDUCE
VISIBILITIES TO NEAR ZERO AT TIMES IN THE MORE EXPOSED AREAS.

* IMPACTS...NORTH TO SOUTH ORIENTED ROADS WAYS WILL BE ESPECIALLY
SUSCEPTIBLE TO STRONG CROSS WINDS. AREAS OF BLOWING SNOW WILL
ALSO PRODUCE SNOWPACKED AND SLICK ROADWAYS...A SEVERELY RESTRICT
VISIBILITIES IN THE MORE OPEN AREAS. HIGHWAY 287 FROM FORT
COLLINS TO THE WYOMING STATELINE WILL BE ESPECIALLY SUSCEPTIBLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A BLIZZARD WATCH MEANS THERE IS A POTENTIAL FOR FALLING AND/OR
BLOWING SNOW WITH STRONG WINDS AND EXTREMELY POOR VISIBILITIES.
THIS CAN LEAD TO WHITEOUT CONDITIONS AND MAKE TRAVEL VERY
DANGEROUS.
 
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yeah it should be fun up your way, im jealous!!

If that happened in the Denver Metro area, there would be something like 5000 accidents and it would take us till noon to get to work, by which time it would be sunny and 45. Don't get me started on people who move here from places where it doesn't snow. Grrr..... enjoy, at least we have something to talk about!

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Excellent example of lee cyclogenesis.  Looks like a nice, quick hit for all locations, but I would think north of 70 will do best.  The location of the 700 MB low is nearly identical between the NAM, GFS, and Euro @ 12Z on Wednesday.  Can't wait to take some turns this weekend!

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