2011/2012 Denver Winter Weather: Maybe this year!

[SCMedic]

WSW:

...EARLY SEASON WINTER STORM HEADED FOR COLORADO...

.A POTENT UPPER LEVEL STORM SYSTEM WILL MOVE TOWARD THE CENTRAL
ROCKIES TUESDAY AND THEN PUSH ACROSS COLORADO TUESDAY NIGHT AND
WEDNESDAY. AN ASSOCIATED COLD FRONT WILL MOVE OVER NORTHEAST
COLORADO TUESDAY AFTERNOON...WITH UPSLOPE FLOW DEEPENING BEHIND
THE FRONT.

AS A RESULT...A MIX OF RAIN AND SNOW WILL FIRST DEVELOP IN THE
HIGH COUNTRY ON TUESDAY...AND THEN SPREAD ACROSS THE PLAINS
TUESDAY EVENING. AS COLD AIR CONTINUES TO INFILTRATE THE
STATE...RAIN WILL CHANGE OVER TO SNOW AND MAY BECOME HEAVY AT
TIMES TUESDAY NIGHT INTO WEDNESDAY.

SOME TREES IN THE FRONT RANGE URBAN CORRIDOR AND THE EASTERN
PLAINS OF COLORADO HAVE NOT YET LOST THEIR LEAVES. AS HEAVY WET
SNOW ACCUMULATES ON THESE TREES...BROKEN TREE LIMBS AND POWER
OUTAGES WILL BE POSSIBLE.

SNOW AND SLUSH MAY ALSO ACCUMULATE ON ROAD SURFACES CREATING
HAZARDOUS DRIVING CONDITIONS.



I still think locals are under forecasting storm totals. We'll see. If I recall with the 09' storm mentioned above, 9News was calling for 3-6" and then calling for another 2-4" after the first day. They were WAAAY off.

[PTPatrick]

Well thing aren't cut in stone yet for sure. 0z nam would be pretty much a non event for metro, wthmst of the heavy QPF in the Cheyenne zones. 0z gfs not quite as wet but still some good snow,. Qpf would be an inch or so instead of the 1.5 potential. But the bullseye is still over metro and not Cheyenne ridge. Will have to watch. Hope our storm isn't fizzling before it starts.




Edit: 0z Canadian trended toward nam with higher pricip over Cheyenne....bummer

[SCMedic]

And here comes the fizzles!

[PTPatrick]

Well, all is not lost yet. Reading this mornings discussions from the local WFO's, nam last night seems to have been outlier and 6z appears to have come around. Nam now wetter than gFS anyway, both would be sigificant snows still.they seem to be swinging from .75 to 1.25 of qpf, which is a good bit for a snow storm. So We shall see. They are calling for 4-8 which seems reasonable given unsettled models.


UPDATE: 12z's came back wetter than last nights or this mornings. NAM now has about 1.5 inch bullsey and GFS back up in the 1.25 range. So that bodes well. Also both seem to show a later start to precip but more of it as snow. As pretty mcuh all the precip falls after the 546 thickness line is south of us

[VoodooCadillac]

Live in FC, work in Cheyenne.....Wednesday AM looks interesting!

[SCMedic]

All trending wetter. I'm calling it now.. 8-12" for the front range cities. That's right. I said it.

[PTPatrick]

Agreed...I think 6 is the low end for I-25 corridor, but I wouldn't be surprised to see 10-12. To get 12 though we'd have to have no melting and every bit of that 1.25 falling at 10:1. I think that's a tall order.

My best guess: 10 downtown, 11 boulder, 12 golden, 14 Ken caryl, 12 Parker, 6 DIA, 6 fort Collins


Also see areas abocve 7500' approaching 20 inches.

[Dencolo]

NAM trending wetter as of 00z run. I like the total estimates you have above. Count me as being on board with those!

[Dencolo]

Update - they must have just looked at the NAM. Up from a 4 to 8" estimate to 8 to 12"!


924 PM MDT MON OCT 24 2011

...WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY EVENING
THROUGH WEDNESDAY AFTERNOON...

A WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY EVENING
THROUGH WEDNESDAY AFTERNOON.

* TIMING...RAIN AND SNOW ARE EXPECTED TO DEVELOP BY TUESDAY
EVENING AND THEN CHANGE TO ALL SNOW BY AROUND MIDNIGHT. SNOW
WILL CONTINUE THROUGH MUCH OF WEDNESDAY AND MAY BE
HEAVY...ESPECIALLY WEDNESDAY MORNING.

* ACCUMULATION/WIND...TOTAL SNOW ACCUMULATIONS OF 4 TO 8 INCHES
WILL BE POSSIBLE IN WELD COUNTY...WITH 6 TO 12 INCHES POSSIBLE
FROM FORT COLLINS SOUTH THROUGH THE DENVER AREA. EVEN HIGHER
AMOUNTS ARE POSSIBLE NEAR THE FOOTHILLS AND SOUTH OF DENVER.
SIGNIFICANT WINDS ARE NOT ANTICIPATED.

* MAIN IMPACT...HEAVY WET SNOW MAY ACCUMULATE ON TREES...
RESULTING IN BROKEN TREE LIMBS AND POWER OUTAGES. ROADS WILL
BECOME SLUSHY OR SNOW COVERED DURING PERIODS OF HEAVY SNOW.

* OTHER IMPACTS...TEMPERATURES WILL DROP SHARPLY WITH READINGS AROUND
FREEZING DURING THE STORM...AND DROPPING INTO THE TEENS ON
WEDNESDAY NIGHT.

[PTPatrick]

Agreed...0z nam and its 1.5 inch bullseye over the metro and foothills probably played a part, hpc agrees showing much of the 1-25 corridor with a 10% chance of a foot. If nam qpf amounts pan out, I think a foot in Denver and 16 around the edges is reasonable...again, there should be a good bed of snow laid own at night, and rates should be heavy over night so that should help much of it stick.


Edit, they updated the disc....basically said previous amounts were low end of guidance so they upped them . Mentioned 8-16 possibly across Denver. Weld and plains away from I-25 seem to be still in questions. Meanwhile GFS, loves Palmer divide and south parks...still around 1-1.25 for Denver it looks like.

[PTPatrick]

Well, continues to look good. Temps may be more of an issue at onset than I originally thought but still sounds like they see changeover before midnight. Based on models though I don't see barely any precip in Denver before midnight. All looks then. Either way qpfs aren't changing, if anything a hair higher. I haven't ever seen model consistency 3-4 days prior like we've seen with this so hopefully we wont wake up tomorrow wondering what happened. WSW now calling for 8-12 in town, up to 18 foothills, 15-16 up against foothills. My point forecast shows 6-10 tonight tonight and 3-5 tomorrow.

[PTPatrick]

Afternoon Discussion is out...not much change. They do seem to be saying they could tweak snow totals up again and that there will be a heavy jet inhanced line somewhere overnight. GFS and NAM are now both solidly in the 1.25-1.75 range for most of the north cetnral mountains and adjacent plains...HPC is now showing most of the area with a 40 - 70% prob of 12 inches plus from this storm. Disc also mentions heavy snow spreading further across plains than normal do to jet. So I think its game time :-D not much left but "nowcasting" as the heavier bands set up over night. Doesnt look like much will happen before bed unfortunately


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
330 PM MDT TUE OCT 25 2011

.SHORT TERM...EVERYTHING SEEMS TO BE COMING TOGETHER WITH SATELLITE
PICTURES SHOWING AN EVOLVING BAND OF PRECIPITATION OVER WYOMING AND
NORTHWESTERN COLORADO. THIS AREA OF ENHANCEMENT SHOULD EXPAND AND
SPREAD OVER OUR FORECAST AREA THROUGH THE NEXT 12 HOURS. LIGHTNING
DETECTION ALSO SHOWS THUNDERSTORMS OVER THE FOUR CORNERS AND UP TO
KGJT. THIS IS INDICATIVE OF THE NEUTRAL STABILITY OF THE AIRMASS
MOVING OVER THE STATE. GUSTY NORTHEAST WINDS ON THE PLAINS HAVE
BEEN INCREASING THE PAST COUPLE HOURS AS COOL AIR FROM WYOMING AND
NEBRASKA CONTINUES MOVING SOUTHWARD. THE TWO UPPER LEVEL JETS HAVE
MOVED INTO POSITION OVER COLORADO AS HAD BEEN FORECAST BY PREVIOUS
MODEL RUNS. THE TWO JETS SHOULD WORK TO ENHANCE DYNAMIC LIFT OVER
THE STATE THROUGH TONIGHT AS THE UPPER TROUGH APPROACHES. MODEL QPF
FIELDS FROM THE NAM AND GFS CONTINUE SHOWING COPIOUS AMOUNTS OF
LIQUID WATER CONTENT FROM THIS STORM...AND ALL THE DYNAMICS MAKES
THESE AMOUNTS BELIEVABLE. THE AREA OF ENHANCED LIFT MAY ALSO
ORGANIZE PRECIPITATION INTO A BROAD BAND OF MODERATE SNOWFALL
THROUGH THE OVERNIGHT HOURS. AREAS FROM THE FOOTHILLS EASTWARD TO
WELD AND ADAMS COUNTIES MAY SEE SNOW FALLING AT THE RATE OF 1 TO 2
INCHES PER HOUR FOR MUCH OF THE NIGHT. WITH THE STRONG DYNAMICS OF
THE STORM...MODERATE SNOW WILL BE ABLE TO EXTEND FURTHER FROM THE
FOOTHILLS THAN TYPICAL STORMS. WINTER STORM WARNING WILL CONTINUE
TONIGHT WITH SNOW AMOUNTS A COUPLE INCHES HIGHER THAN PREVIOUS
FORECAST PACKAGES.

LIGHT AND MODERATE SNOW IN THE MORNING WILL BEGIN TAPERING OFF
DURING THE AFTERNOON HOURS AS THE PROGRESSIVE UPPER TROUGH MOVES
OVER THE NORTHEAST PLAINS AND BEGINS EXITING THE STATE. STRONG
SUBSIDENCE IS EXPECTED BEHIND THE UPPER TROUGH.

[PTPatrick]

Wow, pretty intense echoes already overs reading the metro. Hopefully not much of the QPF is wasted on rain. I'm wondering if this is just bonus as models had verylittle qpf during the evening hours.

[Dencolo]

Pretty much all snow now, just starting to stick to the grass. I'm thinking I'll wake up to about 6-8" on grassy surfaces. We'll see....

[SCMedic]

2" already on the grass and deck with roads starting to stick too. Snowing hard since 8pm. Changeover and heavy precip early. Guessing we'll be on the high on of 10-18".

[PTPatrick]

That's crazy SC...it's been snowin since about 815 here downtown... it really wasn't a good solid changeover until after about 9 temp just hit 32 in te last half hour. Barely dusting cars and grass. Where are you that you already got a couple inches?

[VoodooCadillac]

Haven't been out to "officially" measure yet, but there's at least 6" in Old Town Fort Collins. Noticeable tree damage as well.

[PTPatrick]

FAIL...Don't know what happened. Looks like only north areas got close to forecast...Greeley and Ft Collins got around 6 inches...I have a couple inches of slop. Nothing really even stuck to the concrete good. May get the most during the morning, but I have my doubts. nEXT!

[SCMedic]

I have about 7" on the deck this morning. Still coming down hard. Interesting discussion this morning about the low and the infamous dry slot.

[PTPatrick]

Yeah, SC, you were definitely in that favored strip from north boulder to Greely. I looked again and now up to 3, snowing ok right now. I suspect areas south of 70 will get one last burst this am sometime as the storm swings around. The discussion kind of alludes to that. Looks like areas north of the metro are going to wind down though. we'll see