The Official 2009-2010 Denver winter weather thread

[VoodooCadillac]

Snow started a little later than anticipated in FC - about 3" so far (at 8:30 AM).

Edit - snow tapered off quickly to flurries - so 3" is the grand total. Cold is the story. Already 0 at 6:30 PM, and skies are clearing.

YTD snow:
First storm - 3"
Big storm - 21.5"
3rd storm - 6.5"
12/2/09 - 1.5"
12/6/09 - 10"
12/8/09 - 3"

Total = 45.5"

[PTPatrick]

storm turned out to be a total bust for the front range...I got about 2.5 new inches...big whoop. In any case, its cold as (*&^ here...2 in my yard right now...and winter is still a week and a half away!

[SCMedic]

Yeah, we maybe got another 2" or so. -2 at 8pm when I got home.

FWIW, I was up in Eagle today, and then out in Glenwood Springs. Glenwood looks like they picked up 2.5' of snow! Amazing. It was absolutely nuking when I got into Avon and all the way out.

[PTPatrick]

-17 below at DIA this morning...not a record but close. Closer into town lows seem to have been in the -6 to -10 range. Heat wave today with a high of 18!

[Dencolo]

Yep, having the official weather station at DIA makes for some interesting readings. Eight below at my house.

DIA will nearly always have lower lows and also lower snowfall totals than downtown and the suburbs.

Speaking of the last snowfall, I think we should have forecasted that storm! I have no idea where they were ever seeing the potential for 8" of snow. No model was spitting out that much QPF,even with the high snowfall to liquid ratio projected. The forecasters have done a pretty good job this season so far, but that was a little off.

[SCMedic]

Just saw -16 on the car dash on the way to the gym.

[VoodooCadillac]

-15 at my house in Fort Collins this morning.

[Dencolo]

And I though 10 below was bad. Greeley chimed in at 24 below.

http://www.weather.gov/data/obhistory/KGXY.html

[PTPatrick]

I guess the models were right in keeping th arctic air out of Colorado with this front moving down the plains....to give you some big the gradient is...

Current temps:
Ainsworth, NE 3 above
North Platte NE 15
Rapid City -3
Souix Falls SD 9 above
Denver 53
Cheyenne 42
Akron CO 51...keep in mind that is only a couple hours drive Ogalalla, NE where its currently 17

We've pretty stiff Chinooks blowing off the moutains today that helped to warm us up. You can see the snow clouds and darkness over the mountains, but of course its sunny over Denver and none the precip will make it across.

[Dencolo]

Looks fairly dry in the foreseeable future, with the excpetion of a slight chance in the Friday timeframe. Next shot may arrive just before Christmas according to the GFS. If we want a white Christmas it appears that one is going to have to pan out, especially with the expected sun and temps in the 40s to 50s. Even the north facing yards may have trouble keeping snow if we have 11 days of limited snow until the 25th.

[Dencolo]

Some model discrepencies in the medium term. Differnence between no snow and 3"-6".

THE ECMWF HAS A MUCH STRONGER
SHORTWAVE THAN THE GFS...WITH UPSLOPE FLOW FRIDAY BRINGING ABOUT 0.3
INCHES OF QPF. GFS IS NOT SHOWING ANY UPSLOPE WITH LITTLE
MOISTURE...THEREFORE WILL KEEP THE SLIGHT CHANCE OF PRECIPITATION
FOR THE PLAINS THURSDAY NIGHT INTO FRIDAY.

[VoodooCadillac]

GFS continues to look (even more) promising in the 12/23-12/26 range.

[SCMedic]

Next week is looking interesting with multiple rounds of snow according to the latest. Even hackuweather is mentioning the pattern change along with a white christmas! Hopefully this is 2006 all over again! Ok, probably not, but some mountain dumpage would be awesome to go along with some frontrange snow.

[Dencolo]

Now all of a sudden the GFS is giving Denver 0.5" of QPF on the 22nd and 23rd. That will ensure a white Christmas. If we could get a 15-1 snow-liquid ratio, that would be a good 7-8".

Pretty interesting discussion this morning from the Denver NWS

BY MONDAY NIGHT AND TUESDAY THE ENTIRE WEATHER PATTERN IS MAKING A
LARGE CHANGE AS HIGH AMPLITUDE RIDGING OVER THE EASTERN PACIFIC WILL
ALLOW A DEEP TROUGH TO CARVE ITSELF OUT IN THE WESTERN U.S. THE NAM
AND ECMWF ARE THE STRONGEST AND MOST AGGRESSIVE WITH THIS FEATURE...
AND DROP A CLOSED LOW SOUTHWARD ACROSS OREGON AND CALIFORNIA...WHILE
THE GFS AND MOST OF ITS ENSEMBLES ARE A LITTLE WEAKER AND FARTHER
EAST. AT THIS TIME...I LIKE THE IDEA OF A FARTHER WESTWARD AND THUS
SLOWER SOLUTION GIVEN THE HIGH AMPLITUDE UPSTREAM RIDGING SEEN OVER
THE EASTERN PACIFIC. AS A RESULT...BEST CHANCE OF SNOW FOR THE
FORECAST AREA SHOULD HOLD OFF UNTIL LATE TUESDAY IN THE
MOUNTAINS...AND THEN TUESDAY NIGHT INTO WEDNESDAY NIGHT ON THE
PLAINS AS THE STORM WINDS UP OVER THE CENTRAL PLAINS.

AN INTERESTING NOTE IS THE AMOUNT OF ENERGY THAT THIS SYSTEM COULD
POTENTIALLY TAP INTO WITH A STRONG JET DIVING SOUTH OUT OF ALASKA
AND MEETING UP WITH ANOTHER VERY STRONG SUBTROPICAL JET COMING OFF
THE PACIFIC. THERE ARE SOME MEDIUM RANGE MODELS SUGGESTING A
NEGATIVELY TILTED UPPER TROUGH AS WELL...SO THAT TOO BEARS WATCHING
WHICH WOULD BRING A BETTER CHANCE OF MORE SIGNIFICANT SNOWFALL TO
THE PLAINS. HAVE INCREASED POPS GIVEN THE ABOVE MENTIONED FACTORS.

TEMPERATURES WILL BE MUCH COLDER WITH HIGHS LIKELY STRUGGLING TO GET
ABOVE 20F WEDNESDAY THROUGH CHRISTMAS DAY. SOME OF THE LATEST DATA
SUGGESTS HIGHS POTENTIALLY CLOSER TO 10F THURSDAY AND FRIDAY.
LATEST MOS GUIDANCE IN THE 30S LOOKS WAY TO WARM GIVEN THE
SIGNIFICANT PATTERN CHANGE AND SNOW POTENTIAL.

[srainhoutx]

A bit of a Southern Track and some upsloping may add to those totals forecasted. That is some mighty Deep Cold Air as well. Enjoy your White Christmas.

[SCMedic]

I have a feeling this could be another one of those storms that is underestimated initially. I'm guessing at least 10".

[Dencolo]

Looks like 3 to 7 inches is predicted. Based on the GFS output, it looks like periods of moderate snow can be expected. And that will ensure a white Christmas, which according to the Denver NWS we only get 36% of the time believe it or not!

A CAREFUL CHECK OF PAST WEATHER RECORDS SHOWS THE CHANCES OF HAVING A WHITE CHRISTMAS ARE NOT AS GOOD AS ONE MIGHT EXPECT.

IF HAVING A WHITE CHRISTMAS MEANS HAVING AN INCH OR MORE OF SNOW ON THE GROUND ON CHRISTMAS DAY...THEN THE CHANCES ARE ABOUT 36 PERCENT (39 days in 107 years).

>>>>>>>>>

...WINTER WEATHER ADVISORY IN EFFECT FROM 8 PM TUESDAY TO 5 AM
MST THURSDAY...

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A WINTER
WEATHER ADVISORY FOR SNOW...WHICH IS IN EFFECT FROM 8 PM TUESDAY
TO 5 AM MST THURSDAY.

* TIMING...SNOW WILL DEVELOP TUESDAY EVENING AND CONTINUE INTO
WEDNESDAY. THE SNOW IS EXPECTED TO TAPER OFF LATE WEDNESDAY
AFTERNOON INTO WEDNESDAY NIGHT.

* ACCUMULATION/WIND...SNOW ACCUMULATIONS OVER 3 TO 7 INCHES ARE
EXPECTED BY THURSDAY MORNING. NORTH WINDS OF 5 TO 15 MPH MAY
CAUSE ISOLATED BLOWING SNOW.

[SCMedic]

Snow totals upped this morning as latest model runs have shifted slightly northward. A mention that if the trend continues, Warnings will have to be issued and totals upped again.

Let's keep our fingers crossed!

[srainhoutx]

Good Luck Folks. This will likely be a very wild ride and Stay Safe!

[PTPatrick]

I am bummed I will miss this one...or at least most of it. I am leaving tomorrow morning. If its stronger than forecasted I might not miss it after all b/c my flight would be cancel. Heres hoping for a nice white christmas for you guys but not bad enough to cancel flights!