Mountain West Discussion

[n1vek]

15 minutes ago, skierinvermont said:

Eyeballing it looks like the Euro ups the metro from around 1.5" to 1.9". Decent ~50 mile southward shift in the overall QPF field. And the 500mb looked closer to the GFS than it did before. Still need another 50-75 miles south shift to really focus the upslope over the NW metro area.

I'll be very interested to see how this all models out in the next 12 hours with everything onshore. I could handle a little walk further south. NWS seems pretty good based on their afternoon AFD with that 2-3" qpf range in the metro. Ratios, daytime sun angle may also be a story watching how effectively this will accumulate. That being said, I'll take the moisture however we can get it!

[smokeybandit]

NWS already dropping their amounts east of I-25 even as the Euro holds serve and the GFS ticks south again

[n1vek]

1 hour ago, smokeybandit said:

NWS already dropping their amounts east of I-25 even as the Euro holds serve and the GFS ticks south again

Agreed - GFS southernly trend is there comparing runs this morning. I don't have access to Euro maps, but hopefully OpenSnow posts some views this morning. 

[Metasequoia]

10 minutes ago, n1vek said:

Agreed - GFS southernly trend is there comparing runs this morning. I don't have access to Euro maps, but hopefully OpenSnow posts some views this morning. 

Link to free EURO site.

https://weather.us/model-charts/euro/2021031100/colorado/acc-total-precipitation/20210317-0000z.html

[ValpoVike]

WPC seems to be placing their bets on a more southerly track.  72hr probs of >30" thru 12z Sunday looks a lot like the GFS QPF maps in terms of location.  The light blue is 50-60% prob, which is crazy.

[tarheelwx]

Dropping in from the Southeast forum as my son moved from NC to Broomfield in December. He's headed to Breckinridge Friday evening and then back to Broomfield Sunday evening.  

Here's a great free site for the Euro.  Not sure if you guys have been using it or now.  I use it instead of weather.us site.  It gives nice total snowfall maps rather than just snow depth.

https://www.pivotalweather.com/model.php?m=ecmwf_full&p=sn10_acc&rh=2021031100&fh=120&r=us_c&dpdt=&mc=

TW

[MidlothianWX]

6z GFS holds serve with 5-6" of QPF from Denver north. This is a battle between the Euro and GFS/CMC/UK at this point.

Morning AFD from Boulder:

Quote

The storm total snowfall forecasts were a mix of the global
ensembles with lower weight placed on the GEFS. Amounts in the
Denver metro are in the 15-25 inch range with Boulder and Fort
Collins in the 20-30 inch range. The foothills will see the
highest amounts with 2 to 4 feet likely. Given a more southerly
track of this system, it would not surprise me to see a location
or two in the northern foothills reach 5 feet. The area of
highest uncertainty with regards to impacts will be the eastern
plains. Amounts could be below Winter Storm Warning criteria there
if the warmer solutions pan out. Or those areas could see close
to a foot of snow with high impacts. There is high confidence in
the impacts for the urban corridor and foothills with nearly
impossible travel conditions Saturday night and Sunday. The Winter
Storm Watch was kept due to the uncertainty with snowfall amounts
with this storm especially farther east.

 

[FamouslyHot]

Here's the trend of the cutoff ULL. You can see it getting pushed back south the past several runs.

[n1vek]

Given the audacity of the GFS, gotta assume it caves at least somewhat to the rest of the model consensus. 

[WeatherEmperor]

The GFS is stubborn but, in a way, it hasn't been stubborn, its kind of moved north and then started to come back to where it was originally?  I'd be curious about the relative success rates of the Euro / GFS in forecasting front range weather at this point.  

[MidlothianWX]

12z GFS qpf:

Boulder: 5.2"
Denver: 5.0"

Precip begins roughly 48 hours from now.

[mayjawintastawm]

1 hour ago, tarheelwx said:

Dropping in from the Southeast forum as my son moved from NC to Broomfield in December. He's headed to Breckinridge Friday evening and then back to Broomfield Sunday evening.  

Here's a great free site for the Euro.  Not sure if you guys have been using it or now.  I use it instead of weather.us site.  It gives nice total snowfall maps rather than just snow depth.

https://www.pivotalweather.com/model.php?m=ecmwf_full&p=sn10_acc&rh=2021031100&fh=120&r=us_c&dpdt=&mc=

TW

Thanks for the site! If things go according to plan, "back to Broomfield Sunday evening" might be dicey. Would think about a plan B. OTOH, systems often clear out earlier than forecast, so it might be OK.

[skierinvermont]

1 hour ago, tarheelwx said:

Dropping in from the Southeast forum as my son moved from NC to Broomfield in December. He's headed to Breckinridge Friday evening and then back to Broomfield Sunday evening.  

Here's a great free site for the Euro.  Not sure if you guys have been using it or now.  I use it instead of weather.us site.  It gives nice total snowfall maps rather than just snow depth.

https://www.pivotalweather.com/model.php?m=ecmwf_full&p=sn10_acc&rh=2021031100&fh=120&r=us_c&dpdt=&mc=

TW

You should tell him the interstate will be closed all weekend if the GFS happens. The snow doesn't stop until somewhere around 10pm Sunday night. My guess is the interstate won't open until sometime Monday morning. If the Euro happens there may be some periodic openings if he is lucky. Also Breck is only going to get 6-12"!

[smokeybandit]

I'm still on the losing end (relatively speaking) of the sharp QPF cutoff.  

[n1vek]

12z GFS operational really wraps in some warm air north of the surface low. Obscene snow totals for the higher elevations, but that warm tongue creates a crazy, elevation dependent, gradient up near Fort Collins. As noted above, QPF is still off the charts for both the operation and ensembles. 

[MidlothianWX]

It appears the 12z Euro increased QPF in the Denver/Boulder metro to 2-2.5".

Can any local experts tell me how the Euro typically verifies in heavy upslope scenarios vs. the other globals?

[skierinvermont]

10 minutes ago, MidlothianWX said:

It appears the 12z Euro increased QPF in the Denver/Boulder metro to 2-2.5".

Can any local experts tell me how the Euro typically verifies in heavy upslope scenarios vs. the other globals?

I haven't noticed any patterns. I have noticed the resolution seems to help with some of the terrain.

First we have to resolve the 500mb placement. The the two models still totally disagree on the CA trough, as well as the ridging and kicker behind the storm. Ultimately the placement of the 500mb low is over 100 miles different with a tighter more compact low on the GFS down in Oklahoma panhandle really keeping the flow aloft out of the east in Denver.

Same timestamp gfs vs euro:

 

[CO SciFan]

I wanted to share this nifty 3d forecast map from Evan Fisher at the Carolina Weather Group, he's planning to update it as as new NDFD packages come in: https://carolinaweathergroup.com/temporary-maps/

You can really see some interesting upslope and gradient effects easily this way.  And seeing the crazy totals over the burn scars from the High Park and East Troublesome fires seems like a concern. I hope we are not looking at some nasty flood impacts, thoughts?

[Winteraddict]

What’s the best location to get hotel at from Denver for this event? Boulder or do I have to travel more west or north?

[ValpoVike]

29 minutes ago, CO SciFan said:

I wanted to share this nifty 3d forecast map from Evan Fisher at the Carolina Weather Group, he's planning to update it as as new NDFD packages come in: https://carolinaweathergroup.com/temporary-maps/

You can really see some interesting upslope and gradient effects easily this way.  And seeing the crazy totals over the burn scars from the High Park and East Troublesome fires seems like a concern. I hope we are not looking at some nasty flood impacts, thoughts?

I live in an area that was severely impacted from Cameron Peak, and property owners have been actively working to remove debris from the streams and drainages.  But, yeah there is concern.

[Amped]

1 hour ago, Winteraddict said:

What’s the best location to get hotel at from Denver for this event? Boulder or do I have to travel more west or north?

 Centennial, just south of Denver is elevated a bit and is where the Euro has the jackpot.   

[skierinvermont]

1 hour ago, Winteraddict said:

What’s the best location to get hotel at from Denver for this event? Boulder or do I have to travel more west or north?

Boulder should be good. There will be more in the hills west but it is fun seeing urban environments get this much snow. The Euro did have a random spike in QPF on the south side of Denver, but that has not been consistent across model runs. Generally most runs/ensembles have the higher amounts farther north somewhere from Boulder to Cheyenne but hard to know yet. I'm hoping for the southern GFS solution but think the more likely jackpot is near higher elevations near Fort Collins or Cheyenne... Boulder if we are lucky.

[ValpoVike]

1 hour ago, Winteraddict said:

What’s the best location to get hotel at from Denver for this event? Boulder or do I have to travel more west or north?

For the past couple of days it has been consistent that if you want the maxima you should plan somewhere along Peak-to-Peak highway between Nederland and Estes Park.  Allenspark looks really good, but this time of year not too many places to stay.  Estes Park has a lot of hotels, along with great views, so that might work best for you.

[Chinook]

The GFS throws in so much warm air that has rain at 4800ft - 4900 ft at Greeley. The Euro/Canadian/UKMET have significant snowfall values at Greeley, though.

[WeatherEmperor]

5 minutes ago, Chinook said:

The GFS throws in so much warm air that has rain at 4800ft - 4900 ft at Greeley. The Euro/Canadian/UKMET have significant snowfall values at Greeley, though.

Yeah this is what makes me think this situation is unsolved.  Location, temp, are still unresolved.  I don't think any of the forecasts are TOO wild for major metro areas but because of these inconsistencies I am actually concerned we end up with something weird out of climate change's book, and that that might be something very unexpected.

[ValpoVike]

3 minutes ago, WeatherEmperor said:

Yeah this is what makes me think this situation is unsolved.  Location, temp, are still unresolved.  I don't think any of the forecasts are TOO wild for major metro areas but because of these inconsistencies I am actually concerned we end up with something weird out of climate change's book, and that that might be something very unexpected.

Seriously, what? 

 

[smokeybandit]

GFS just dropped me from 20" down to 10" from 12z.

For a model that was steadfast for a long time, it's all over the place now.

[skierinvermont]

18z GFS went north about 50 miles. The overall 500mb map didn't change a ton, but the way the vorticity seemed to wrap around at the end dragged the 500mb low north. Hoping it is just a blip because the overall 500mb map is pretty different from the Euro still even by hour 12.

[skierinvermont]

4 minutes ago, smokeybandit said:

GFS just dropped me from 20" down to 10" from 12z.

For a model that was steadfast for a long time, it's all over the place now.

I still see 2.2" QPF in Parker down from about 3.1" on the 12z.

[smokeybandit]

A lot of that is probably rain.