The Official 2009-2010 Denver winter weather thread

[PTPatrick]

No change from my thinking earlier today. Took this beautiful day to work in the yard, throw down the winter fertilizer, re mulch and plant tulip bulbs. Fall yard work is actually kinda nice. I think I like it more than spring because you dont have the looming dread of what will happen to your beautiful stuff if mother nature doesnt play nice, such as with hail storms and drought/heat. Not to mention the weather is nicer here in fall than spring. The breeze blowing in ahead of the front really helped me cool off that last little bit this afternoon when it was around 80. In any case, if snow doesnt happen it doesnt happen, I have my sights set on the 300 hour GFS...looks like a major cold front, with freezing thicknessess and precip well into Denverm around October 2.

[VoodooCadillac]

I did my yardwork yesterday (Saturday).

Went to RMNP this AM. Trip included a stop at the Alpine Visitor Center at the top around 11:00AM. It was 42 degrees, wind chill 35 degrees. Precip moving in from the West.

By the time we got back down to the Elk Viewing areas - snow had started above about 11K. Also saw (via the Denver news channels) that there was snow at Loveland Pass.

[SCMedic]

TEMPERATURES WILL BE QUITE COOL AND
SNOW LEVELS WILL DROP QUITE A BIT...BUT SHOULD STAY IN THE
FOOTHILLS. MODEL SOUNDINGS LOOK LIKE THE LOWEST LEVELS ON THE
PLAINS WILL REMAIN WARM ENOUGH TO KEEP PRECIPITATION LIQUID. OVER
THE NEXT FEW MODEL CYCLES IT IS POSSIBLE THAT TEMPERATURE FIELDS
WILL BE COOLER THAN LAST EVENINGS RUNS WHICH MAY REQUIRE SNOW LEVELS
ACROSS OUR FORECAST AREA TO BE LOWERED CLOSER TO THE PLAINS ON
TUESDAY AND WEDNESDAY. WILL NOT MAKE THAT CALL NOW...BUT WILL WAIT
FOR THE BOUNDARY LAYER THERMAL STRUCTURE THAT IS PRODUCING SNOW IN
WYOMING THIS MORNING TO MAKE ITS WAY INTO THE UPCOMING MODEL RUNS.



Keep your fingers crossed!

[PTPatrick]

The north wind this morning is quite chilly. My air temp was 43 this morning when I walked the dog, but the wind definately made it light jacket weather. First morning like that since back in April. Felt good, and certainly helped wake me on up a groggy monday.

[SCMedic]

Rain/snow mix here in Erie. Seems the heavier rain bands are pulling down the cold air. 39 currently.

[srainhoutx]

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
336 PM EDT MON SEP 21 2009

VALID 00Z TUE SEP 22 2009 - 00Z FRI SEP 25 2009


DAY 1...

THE PROBABILITY OF SIGNIFICANT ICING AND/OR SNOW IS LESS THAN 10
PERCENT.

DAYS 2/3...

NORTHERN COLORADO ROCKIES...

PERSISTENCE OF A QUASI-STATIONARY UPPER-LEVEL LOW...COLD POOL
ALOFT AND ASSOCIATED SHORTWAVE ENERGY ENTERING THE BASE OF THE
TROUGH SUPPORT A SLIGHT RISK OF 4 INCH SNOWFALL ACCUMULATIONS
ALONG THE CONTINENTAL DIVIDE OF NORTH CENTRAL COLORADO...WITH
LIGHT SNOWFALL ACCUMULATIONS ACROSS THE SAN JUANS AND SANGRE DE
CRISTOS OF SRN CO/NRN NM.

HPC SNOWFALL FORECAST STEERED AWAY FROM THE WESTERN OUTLIER TODAY
AT H5...THE 12Z GFS ON DAY3...WHICH WOULD BRING THE HIGHEST QPF
VALUES...AND BEST SNOW POTENTIAL TO THE SAN JUANS VERSUS THE
SANGRE DE CRISTOS...WHICH IS THE 12Z NAM/00Z ECMWF SOLUTION.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

VOJTESAK

[PTPatrick]

Well, I got my september snow. It was wet and measly and didnt come close to even dusting anything, but as far as I am concerned frozen stuff falling from the heavens that is not hail, counts under the snow/winter precip category. It lasted down here in Denver for about 5 minutes.

[iorange55]

Lucky! Hopefully thats a good sign of things to come.

[PTPatrick]

i hit on this issue some last winter, and little did I know there was a blogger that was a man after my heart that has done way more research on the subject than me. The subject being the idiocy of moving the offical Denver weather station from Stapleton to DIA. His stats really illustrate the difference in microclimate across the metro area. its 3 differnt sections, but makes a lot of sense. I realize there are those that would argue that no matter what the average weather for given local in denver is differnt from another and that measuring one place is just as good as any, but i think the data shows that differences in DIA and central Denver or even Aurora are more than just chance differences, but rather, truly different microclimates. And if we are using the numbers for accurate historical comparison, then we are comparing apples and oranges. I dont understand why its so difficult for NWS to just use the official data from Buckley AFB or for that matter just go back to measuring at stapleton(the station is still there!). I always pay more attention to buckley's info than DIA's anyway. Even Jeffco airport is more similar to downtown weather it seems than DIA. This guys stats show that DIA on average over the last 14 years has averages 2 inches less precip than Buckley, which is much more likely to be an accurate comparison to Denver. For a city that averages only 15 inches a year, 2 inches is lot to lop off the historical record.

http://www.examiner.com/x-219-Denver-We ... k-attached

http://www.examiner.com/x-219-Denver-We ... hed-Part-2

http://www.examiner.com/x-219-Denver-We ... ?#comments

[PTPatrick]

Models QPF's not looking all that impressive, but I guess since its so early in the year they want to make sure people prepare. The watch says 6-12, but the point forecast for castle rock says 3-5 inches which is not their WSW criteria. Also of note, they are now saying rain snow mix in the urban corrider overnight tonight. Bring it on


URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE DENVER CO
431 AM MDT TUE SEP 22 2009

......EARLY SEASON STORM MAY BRING HEAVY SNOW TO THE
MOUNTAINS...FOOTHILLS AND PALMER DIVIDE LATE TONIGHT THROUGH
WEDNESDAY...

.AN EARLY SEASON STORM SYSTEM WILL DEVELOP OVER WESTERN KANSAS AND THEN
REMAIN NEARLY STATIONARY THROUGH WEDNESDAY. MOIST UPSLOPE FLOW
WILL DEVELOP IN THE MOUNTAINS...FOOTHILLS AND OVER THE PALMER
DIVIDE LATE TONIGHT THROUGH WEDNESDAY AND MAY ALLOW FOR THE
DEVELOPMENT OF HEAVY SNOW ABOVE 6500 FEET.

COZ033>036-041-221845-
/O.NEW.KBOU.WS.A.0007.090923T0900Z-090924T0000Z/
SOUTH AND EAST JACKSON/LARIMER/NORTH AND NORTHEAST GRAND/
NORTHWEST BOULDER COUNTIES ABOVE 9000 FEET-
SOUTH AND SOUTHEAST GRAND/WEST CENTRAL AND SOUTHWEST BOULDER/
GILPIN/CLEAR CREEK/SUMMIT/NORTH AND WEST PARK COUNTIES ABOVE
9000 FEET-LARIMER AND BOULDER COUNTIES BETWEEN 6000 AND 9000 FEET-
JEFFERSON AND WEST DOUGLAS COUNTIES ABOVE 6000 FEET/GILPIN/CLEAR
CREEK/NORTHEAST PARK COUNTIES BELOW 9000 FEET-
ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES ABOVE 6000 FEET-
INCLUDING THE CITIES OF...CAMERON PASS...
LARAMIE AND MEDICINE BOW MOUNTAINS...RABBIT EARS RANGE...
ROCKY MOUNTAIN NATIONAL PARK...WILLOW CREEK PASS...
BERTHOUD PASS...BRECKENRIDGE...EAST SLOPES MOSQUITO RANGE...
EAST SLOPES SOUTHERN GORE RANGE...EISENHOWER TUNNEL...
INDIAN PEAKS...KENOSHA MOUNTAINS...MOUNT EVANS...
WILLIAMS FORK MOUNTAINS...WINTER PARK...ESTES PARK...GLENDEVEY...
NEDERLAND...RED FEATHER LAKES...BAILEY...CENTRAL CITY...
EVERGREEN...GEORGETOWN...IDAHO SPRINGS...WESTCREEK...
CASTLE ROCK...ELBERT...FONDIS...KIOWA...LARKSPUR
431 AM MDT TUE SEP 22 2009

...WINTER STORM WATCH IN EFFECT FROM LATE TONIGHT THROUGH
WEDNESDAY AFTERNOON...

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A WINTER STORM
WATCH...WHICH IS IN EFFECT FROM LATE TONIGHT THROUGH WEDNESDAY
AFTERNOON.

SNOW WILL DEVELOP LATE TONIGHT IN THE MOUNTAINS...FOOTHILLS AND
OVER THE PALMER DIVIDE AND CONTINUE THROUGH WEDNESDAY AFTERNOON.
SNOW MAY BECOME HEAVY AT TIMES. SNOWFALL ACCUMULATIONS BY LATE
WEDNESDAY AFTERNOON MAY RANGE FROM 6 TO 12 INCHES. NORTH WINDS OF
10 TO 20 MPH WITH GUSTS TO 30 MPH MAY CAUSE REDUCED VISIBILITES AT
TIMES DUE TO BLOWING SNOW ESPECIALLY OVER THE PALMER DIVIDE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR A
HAZARDOUS WINTER WEATHER EVENT IN AND CLOSE TO THE WATCH AREA.
SIGNIFICANT SNOW ACCUMULATIONS MAY OCCUR THAT COULD IMPACT
TRAVEL. STAY TUNED TO THE NATIONAL WEATHER SERVICE OR YOUR LOCAL
NEWS MEDIA FOR THE LATEST UPDATES AND POSSIBLE WARNING CONCERNING
THIS POTENTIAL WINTER STORM.

[SCMedic]

I saw the mention of rain/snow this morning when I got up. I hope it pans out. I know I definately had some flakes up here yesterday. Only in CO on the last day of summer, can it snow.

Local stations actually mentioned a full changeover to snow overnight and early AM tomorrow. Only mentioned 1" accum, but that's expected due to the warm ground, and it being September.

[SCMedic]

"LOCAL OROGRAPHIC
SNOW MODEL PRODUCED A FOOT OF SNOW IN 12 HOURS"

Foothills will be kicking tonight!


"MAIN IMPACT IS LIKELY TO BE
HEAVY ACCUMULATIONS ABOVE 7 OR 8 THOUSAND FEET...AND ALSO POSSIBLY
TREE DAMAGE IF WE DO GET MUCH SNOW DOWN INTO THE CITY. SOIL
TEMPERATURES ARE AROUND 50 AT THE SURFACE AND CLOSER TO 60 DOWN A
FEW INCHES...SO THERE WILL BE PLENTY OF MELTING ON THE HIGHWAYS
AROUND DENVER."

Interesting. It looks like things could be coming together for a decent snow event overnight and into the morning! They're very cautious in their wording, but the vibe is there that they seem to think it's a good possibility we could see some wet frozen stuff.

[PTPatrick]

They have removed snow from the point cast for pretty much the whole area below 5500 ft, but the discussion and zone forecast say up to 2 inches tonight and 2 inches tomorrow for Denver and westernArap/Adams. So not sure what to believe. I would tend to believe the discussion and zone forecast over the point forecast though, as that often seems overly arbitrary(ie.snow in centennial and all rain in greenwood village)

[VoodooCadillac]

Nothing in Fort Collins. Too warm, too dry.

The long range GFS model continues to look interesting in the 10/1 - 10/2 range.

[PTPatrick]

nothing in Denver today but rain, and virtually nothing in the foothills. Looks like the only peeps that will end up with anything out of this storm are elevations above 10000 and possibly the top of monument hill down to around Elizabeth and Castle Rock. And of course any snow for the latter 2 is about 24 hours too late. This has been a rather peculiar storm, certainly not well handled by the models from the beginning. I know the NWS had to be pulling their hair out over this thing. From snow in too low an elevation Monday morning to rain or no precip at all at high elevations.

Tonight it looks like the final round of any decent precip in the front range , although it looks like clouds and maybe a bit of drizzle here and there will linger through Friday evening, when the upper low will FINALLY move out into NE. I dont think I have even seen 5 straight cloudy days in Denver, which is testiment to how bizarre this upper low hanging out around here has been.

Should finally warm up and clouds move out saturday with a few days of nice weather before GFS advertises another cool shot with again, possible rain/snow in the front range around mid to late week. Of note, GFS and ECMWF are in agreement here and if Euro is right the late week storm could be doozy for the plains and midwest. Of course by then it could be a blizzard or nothing at all as 8 days is an enternity with this pattern. GFS follows that with another trough and storm around day 13....so suffice it to say we could be looking at a stormy and cool pattern on the horizon, esp considering for early october. I do NOT think we will be waiting till November 18th for snow again this year

[VoodooCadillac]

Various modeling software has consistently been showing 10/1-10/2 as our next good chance for precip., and continues to do so. This is now only 5-6 days out - so nice consistency from the models. Will it be cold enough along the urban corridor to produce snow????

[PTPatrick]

So much for this weeks storms. Darn GFS...

[Dencolo]

The latest GFS runs show a lot of little disturbences followed by something that may be a little more substantial in about a week. If either the little one's can turn out bigger or the big one can materialize, than we'd be in luck. Either way, I agree - we won't have to wait until Nov for snow this year.

[SCMedic]

Looks like early next week could bring the first snows of the season to the Denver area. Finally an actual mention in the forecast!

[PTPatrick]

0z GFS tonight not so bullish on Mondays storm. Still looks like we could get drizzle or snow flurries on monday night, but it may end up like tomorrows storm and be too far north give us any upslope. Its seems to hint at another storm and general troughiness on the Monday storms tail though sometime midweek. ECMWF is doing something similiar, taking mondays storm north of us through WY and bringing a small storm through midweek that ejects out of the SW. Models are really struggling with the 6-7 day time frame right. Either way it looks unsettled and I am certainly not hanging my hat on anything right now. If one things certain, its that the models will change.