Official 2010/11 Denver - I hate La Nina Thread

[PTPatrick]

No kidding Dencolo! Its just slowed down a bit here. up to about 3.5-4 inches here downtown. I just made the trek from SW Denver and it def was worse at that time the further north I got. Here in downtown everything is just pure ice on the roads except the most heavily traveled. I pretty much skidded all the way to grocery store. You can tell there was no real mag chloride buildup on the side roads from the storms we should have had the past 2 months. That combined with the cold I think is spelling an icy mess most folks dont really expect too much. Its pretty seldom we have this much snow WHILE its this cold....normally snows then gets cold. Going to be interesting!

Meanwhile models now have most of the metro just under .5 QPF. Best lift seems southaest of us. Ultimately this doesnt even look like classic upsloap on radar. If it does kick up, I would no be surprised to see the 3-6 more inchs they talked about in this afternoons discussion.



PS...its now 12 here...2 in Cheyenne! wont be long before we are single digits down here.

[zephyr99]

16:15 Conifer: 8 degrees, 2.5" of snow. Snowing very lightly for past several hours. I don't see 6-10 inches unless something changes. Nice to see some snow anyhow. Otherwise, this storm is a bust for my area.

[Dencolo]

Some varied snowfall reports. Looks like Boulder has been hit the hardest. Lull right now, let's see what the rest of the night brings.

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DENVER CO
1035 PM MST THU DEC 30 2010

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..

1005 PM SNOW 12 SE AURORA 39.58N 104.65W
12/30/2010 M4.6 INCH ARAPAHOE CO TRAINED SPOTTER

1000 PM HEAVY SNOW 2 SW GOLDEN 39.71N 105.25W
12/30/2010 M8.0 INCH JEFFERSON CO TRAINED SPOTTER

1000 PM SNOW 5 E BOULDER 40.03N 105.16W
12/30/2010 M5.5 INCH BOULDER CO TRAINED SPOTTER

0955 PM HEAVY SNOW 3 S BOULDER 39.98N 105.25W
12/30/2010 M8.2 INCH BOULDER CO TRAINED SPOTTER

0937 PM SNOW 1 W NORTHGLENN 39.91N 104.99W
12/30/2010 M3.0 INCH ADAMS CO TRAINED SPOTTER

0930 PM SNOW 12 NW GOLDEN 39.86N 105.38W
12/30/2010 M3.5 INCH JEFFERSON CO TRAINED SPOTTER

0929 PM SNOW 3 E HIGHLANDS RANCH 39.55N 104.92W
12/30/2010 M4.0 INCH DOUGLAS CO TRAINED SPOTTER

0919 PM SNOW 3 NNE BAILEY 39.43N 105.44W
12/30/2010 M4.5 INCH PARK CO TRAINED SPOTTER

0916 PM SNOW 1 SW WESTMINSTER 39.87N 105.06W
12/30/2010 M3.4 INCH JEFFERSON CO TRAINED SPOTTER

0912 PM SNOW 3 WSW CONIFER 39.50N 105.35W
12/30/2010 M5.0 INCH JEFFERSON CO TRAINED SPOTTER

0912 PM HEAVY SNOW GENESEE 39.69N 105.27W
12/30/2010 M6.3 INCH JEFFERSON CO TRAINED SPOTTER

0906 PM SNOW ILIFF 40.76N 103.07W
12/30/2010 M5.5 INCH LOGAN CO TRAINED SPOTTER

[miacane2006]

I've just moved to downtown denver from miami and i've been expecting snow storm after snow storm and I got to say I'm really disappointed. We've only had one major storm and that lasted one day. I really hope we get something else soon.

[PTPatrick]

Posted this in the siberia thread. Some arctic cold is knocking on denvers door that will make last weaks seem balmy. If some of the models hold true we could flirt with a below zero high or 2. That is tough to say at this point but it has been in a long time since that has happened.
The last time Denver failed to reach 0 in a 24 hour perios was januaru 1997...we are way overdue.

Heres the info I could find about consecutive hours below zero:
The following is a list of Denver's 10 longest cold streaks, and the number of consecutive hours with temperatures below zero.
Dec. 20-25, 1983 -- 115 Hours
Dec. 8-12, 1932 -- 91 Hours
Dec. 19-23, 1990 -- 86 Hours
Feb. 1-6, 1989 -- 69 Hours
Jan. 10-13, 1963 -- 64 Hours
Jan. 11-14, 1997 -- 60 Hours
Jan. 7-8, 1937 -- 56 Hours
Jan. 20-22, 1937 -- 53 Hours
Feb. 2-3, 1883 -- 48 Hours
Jan. 28-30, 1951 -- 45 Hours


Of note: 1932, 1989, 1990 were La nina years, so it can happen.
also of note: 1989 was FEBRUARY, not the infamous, December 1989 cold...that I guess was shunted east, because December 89 didnt even make the list...although I think it did feature a below zero high.

Snippet from the DIsc...
SUNDAY AND BEYOND...GENERAL CONSENSUS OF THE AVAILABLE MODELS POINT
TO A BIG WEATHER CHANGE FOR THE REGION BEGINNING SUNDAY. 12Z GFS AND
ECMWF AND CANADIAN GEM...AND THE 12Z AND 18Z RUNS OF THE NAM SHOW A
POTENT AND VERY COLD TROUGH DIVING SEWRD OUT OF PACIFIC NORTHWEST
AND NRN ROCKY MTN REGION ON SATURDAY...AND EVENTUALLY OVER THE NRN
AND CNTRL ROCKY MTN REGION BY SUNDAY. ACCOMPANYING THIS PROGRESSIVE
TROUGH IS A STRONG ARCTIC COLD FRONT WHICH MODELS SHOW SLIDING DOWN
THE LEE SLOPE OF THE ROCKIES AND INTO NERN COLORADO BY EARLY SUNDAY
MORNING. BELIEVE WE/LL SEE A PERIOD OF LIGHT TO MODERATE SNOWFALL
WITH ITS PASSAGE AND FOR SEVERAL HOURS AFTERWORDS ACROSS NORTHEAST
COLORADO DURING THE DAY SUNDAY. THERE/S STILL SOME QUESTION AS TO
SNOW AMOUNTS. AT THIS TIME DO NOT SEE MUCH EXCEPT PERHAPS UP ALONG
THE FOOTHILLS AND OVER THE PALMER DIVIDE WHICH OROGRAPHICALLY FAVOR
A N-NELY SFC-700MB FLOW. TEMPERATURES WILL ONLY GET COLDER THROUGH
THE DAY WITH FALLING HEIGHTS AS THE UPPER TROUGH PASSES OVERHEAD.
MAX TEMPS ARE LIKELY REACHED BY NOON ASSUMING CURRENT MODELS HAVE
TIMED ALL THIS CORRECTLY. A GUARDED ASSUMPTION TO SAY THE LEAST. AS
THE UPPER RIDGE CONTINUES TO BUILD ALONE THE WEST COAST THE STRONG
NWLY FLOW ON THE BACK SIDE OF THE UPPER TROUGH OVER US WILL DRIVE
INCREASINGLY COLD AIR DOWN FROM THE FRIGID NWRN REACHES OF CANADA.
COULD SEE SOME OF THE COLDEST AIR IF NOT THE COLDEST AIR OF THIS
YOUNG WINTER SEASON NEXT WEEK. HOWEVER...PROSPECTS FOR MUCH SNOWFALL
APPEARS SLIM. STAY TUNE AS THE MODELS HAVE BEEN FLUCTUATING ALL OVER
THE PLACE WITH THIS ONE.

[SCMedic]

It was nice to get a little snow last week, and is a bit disappointing that the models have wavered back towards a dryer/cold solution for Sunday and the upcoming week.

The story will definitely be the cold. Monday may not get out of single digits to -20 below at night. Stay warm.

[cycloneye]

SCMedic,here is the January update by CPC and it has La Nina hanging on moderate to strong thru the Spring.

http://www.cpc.ncep.noaa.gov/products/a ... odisc.html

[Dencolo]

While January is only supposed to be Denver's 6th snowiest month on average, we may be in for a few storms to get us up above the Jan average. Look at the storm track Accuweather has proposed for later in January. That's close to prime upslope potential.

Also from Accuweather : "More waves of arctic air will invade the country, starting late this week and continuing through next week and beyond. The period from Jan. 10-20 is when Bastardi expects the core of the cold to be in place, with the northern Plains in the heart of it. He says places from Chicago to Denver could have one or two days with high temperatures below zero during this time."

http://www.accuweather.com/blogs/news/s ... ary-we.asp

[PTPatrick]

Agree with you DENCOLO. Looking at long rang GFS, the pattern does start to look pretty prime for continuous invasions of cold air. I think aside from a quick warm up to mid 30-40 range thursday and friday, we will likely spend much of the next 2 weeks with highs below freezing.

Also of note, the local forecast discussion keeps blowing off the chances of accums this sunday evning/monday over the urban corridor. But the reality is both NAM and GFS are is good agreement with at least 6 inches of the white stuff. And that is only if its 10:1 ratio. Suspect it would be closer to 8 in Denver on GFS, 6 on NAM. The palmer divide could easily approad 8-12 on either model. The roads will not be melting until at least thursday. The latest 0z NAM shows highs in the single digits for Monday-Tuesday, teens Wednesday, 30s Thursday-Friday.

After that it shows a lot of cold air sitting around montana....like 30s below zero lows by monday of next week. If it breaks loose we will be in the deep freeze again.

EDIT: I should add, the model currently doesnt have all of that dropping this far south on MOnday, but it does show us flirting with below zero temps again for lows(right now mainly eastern plains). It appears to do battle with warming temps oozing from the southwest...problem is these shallow cold air masses can pool against the divide...SW CO could easily be 40s for highs in this kind of situation while Denver sits int he single digits...just depens on if there is SW flow. Having said that, I would not expect any model to handle this well in th 10 day plus time frame.

[Dencolo]

Finally some guidance by the Denver office via an HWO. Like you said PTPatrick, they are saying in excess of 6" is possible.

The GFS has consistently predicted between 0.6 and 0.7" of QPF for the Denver area. And with the cold in place ratios could easily be above 10:1. I vote for 6-10" of white stuff across the urban corridor!

UPSLOPE CONDITIONS FOLLOWING THE PASSAGE OF A COLD FRONT WILL ALLOW
FOR ACCUMULATING SNOWFALL TO DEVELOP IN AND NEAR THE FRONT RANGE
FOOTHILLS AND ACROSS MUCH OF THE PLAINS OF NORTHEAST COLORADO. MUCH
OF THE SNOWFALL WILL OCCUR SUNDAY AFTERNOON INTO MONDAY MORNING WITH
THE POTENTIAL FOR IN EXCESS OF 6 INCHES OF SNOW BY LATE MONDAY.

IT WILL BE MUCH COLDER MONDAY AND TUESDAY WITH DECREASING CLOUDS AND
AN ARCTIC AIRMASS IN PLACE. BELOW ZERO TEMPERATURES MAY OCCUR ACROSS
MUCH OF THE REGION BY TUESDAY MORNING....WITH HIGH TEMPERATURES
STRUGGLING TO REACH THE TEENS. WARMER AND DRIER CONDITIONS
WILL RETURN TO THE REGION BY WEDNESDAY.

[SCMedic]

Finally some guidance by the Denver office via an HWO. Like you said PTPatrick, they are saying in excess of 6" is possible.

The GFS has consistently predicted between 0.6 and 0.7" of QPF for the Denver area. And with the cold in place ratios could easily be above 10:1. I vote for 6-10" of white stuff across the urban corridor!

UPSLOPE CONDITIONS FOLLOWING THE PASSAGE OF A COLD FRONT WILL ALLOW
FOR ACCUMULATING SNOWFALL TO DEVELOP IN AND NEAR THE FRONT RANGE
FOOTHILLS AND ACROSS MUCH OF THE PLAINS OF NORTHEAST COLORADO. MUCH
OF THE SNOWFALL WILL OCCUR SUNDAY AFTERNOON INTO MONDAY MORNING WITH
THE POTENTIAL FOR IN EXCESS OF 6 INCHES OF SNOW BY LATE MONDAY.

IT WILL BE MUCH COLDER MONDAY AND TUESDAY WITH DECREASING CLOUDS AND
AN ARCTIC AIRMASS IN PLACE. BELOW ZERO TEMPERATURES MAY OCCUR ACROSS
MUCH OF THE REGION BY TUESDAY MORNING....WITH HIGH TEMPERATURES
STRUGGLING TO REACH THE TEENS. WARMER AND DRIER CONDITIONS
WILL RETURN TO THE REGION BY WEDNESDAY.

.7" of QPF with this cold air and great setup for dendritic crystal growth should yield closer to 15:1 ratios.. I'm guessing this may be a surprise for us in the 8-10" range across the frontrange/adjacent plains.

[miacane2006]

Should I be expecting snow in downtown denver this weekend from january 8th through the 10th?

[SCMedic]

6-12" Sunday afternoon through Monday afternoon. Heaviest Sunday night through Monday morning. Very cold temps too.

[Dencolo]

Here is the WSW out of the Denver office. I am expecting a little closer to the 10" part on the southwest side, as the model trends seem to be on the upswing.

...WINTER STORM WATCH REMAINS IN EFFECT FROM SUNDAY AFTERNOON
THROUGH MONDAY AFTERNOON...

A WINTER STORM WATCH REMAINS IN EFFECT FROM SUNDAY AFTERNOON
THROUGH MONDAY AFTERNOON.

* TIMING...SNOW WILL INCREASE OVER THE FRONT RANGE FOOTHILLS AND
ADJACENT PLAINS SUNDAY AFTERNOON...THEN SPREAD OVER ALL OF
NORTHEAST COLORADO BY SUNDAY NIGHT.

* ACCUMULATION/WIND...THERE IS THE POTENTIAL FOR SNOW
ACCUMULATIONS OF 5 TO 10 INCHES OVER THE WATCH AREA WITH LOCALLY
HIGHER AMOUNTS IN THE FRONT RANGE FOOTHILLS AND PALMER DIVIDE.
NORTHERLY WINDS WILL INCREASE BY MONDAY WITH SPEEDS OF 15 TO 25
MPH ON THE PLAINS...CREATING AREAS OF BLOWING AND DRIFTING
SNOW.

* MAIN IMPACT...ROADS WILL BECOME ICY AND SNOWPACKED ON SUNDAY
NIGHT AND MONDAY. IN ADDITION...TEMPERATURES ON MONDAY WILL
TURN VERY COLD WITH READINGS ONLY IN THE SINGLE DIGITS SUNDAY
NIGHT AND TEENS ON MONDAY.

[PTPatrick]

not much appears to have changed, other than models coming in with a little more QPF for the metro. now showing .75 to 1 inch. with good dendritic growth, esp later tomorrow, I dont think a foot in Denver (central and southward) would be out of the question. In light of the last dud of a storm, I am leaning toward lower, probably 8-10...although we wont loose much from melting at the onset like last storm, as I think the last cold spell did a good job of bringing ground and surface temps down. I think 10-15 inches is not out of the question in the Palmer Divide and foothills as well. I am not sure what the criteria for a Winter storm warning is, but I am surprised that they went with an advisory, given the fact that roads will be poor at these temps (mag chloride only works above about 20 degrees). I dont think I have ever seen 6-10 inches in Denver not get a WSW hoisted...which leads me to believe they once bitten twice shy with last weeks system.

[SCMedic]

I'm thinking 10-12" across the metro area, based on qpf, winds and prolonged lift.

Winter weather advisory vs. WSW is due to length of storm and general lack of wind.

[PTPatrick]

I smell another busted forecast. Woke up this morning and drove to work in thornton and the roads were trash. There was a band parked ove arvada/westminster/thornton kind of east west at around 730. There had been no plows, and close to 6 inches had fallen in that area by midmorning. fortunatey once plows cam out things calmed down. Downtown I am up to about 3.5...
This mornings disc said NAM was trending toward heavy QPF this morning and then not much tonight, but GFS was still thinking more tonight. I have a feeling based on radar NAM may have ben right. its clear behind us. This might be it other than light snow later tonight. hopefully NAM is wrong and there will be some more tonight. We shall see....

[SCMedic]

Models still on track for heavier snow this evening. Nam is the outlier, with a slightly more southern track. We'll see.

[PTPatrick]

Well the radar is finally filling back in back in the metro. Looks like a nasty band parked across castle rock to Parker out toward. Looked at the cams from around castle pines pwky and it looks like it could be wolf creek pass. in any case, i re-measured and up to 5.5 inches. Not sure where it came from but I will take it. Just gonna take a good 8 hrs of slow steady light stuff and I think 8 could still materialize here downtown. I am hunkered down just watchin it snow, not feeling too great today

[PTPatrick]

still snowing and radar not looking too bad. 0z model keep the moisture in. I am to 8-9 inches depending on where I put the stick...seems like once its kicked up its been coming down about .5 to 1 inch per hour. I think we are on tap now for about 2 -3 more inches, so downtown could end up at close to a foot...not bad Models dont stop the snow til tomorrow afternoon. Commute tomorrow going to suck.

Looking out into next week...maybe a little front next weekend with a little snow. EURO is consistent on building some nasty cold high prssure in west central canada but keeps flow zonal so no more arctic invasions on the horizon, but as long as the cold is up there you have to watch your back.