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Hello everybody,

The rain and snow that fell during the wee hours into mid-morning Saturday was fantastic as we increased our soil moisture with .35 inches of precip in town.  That could be critical because you never know when it might happen again.  Lets talk about the next few days.  By the way, if the models are right, we are dry and windy for much of next week which means Saturday morning’s showers were important.

Sunday – Sunday will be a totally different day than it was on Saturday.  A new ridge aloft builds over the region and with this ridge comes subsidence or sinking air.  What that means is the atmosphere will be much more stable.  The cumulus clouds that form on Sunday wont have nearly the vertical extent as they did on Saturday and they wont produce any showers.  Overall concerning skycover, I think scattered cumulus clouds will be the rule with a few cirrus clouds mixed in.  It looks like a very nice day with warming temps and we will take a run at 70 in town.

Monday - Monday will be a beautiful day.  It will be the nicest day of the Spring so far.  The ridge aloft amplifies over the region and this brings a very dry atmosphere to Aspen and vicinity.  Look for a ton of sunshine with perhaps a touch of cirrus and a couple flat cumulus clouds.  Overall mostly sunny looks fine.  Temps will soar in the morning and be at 72 by noon.  I’m thinking we hit 77 for a high temp in town with 82 to 85 downvalley.  Breezes pick up in the afternoon due to the strong warming and 15 to 20mph looks appropriate.  Humidity will be low in the afternoon along with some breezes so dont burn anything.

Tuesday – We will be ahead of a new cold front on Tuesday.  The atmosphere will be well mixed ahead of this boundary so look for a windy day developing.  Forecast soundings are easily giving us 20 to 35mph and gusty during the afternoon once we establish good mixing.  Overall the day looks dry ahead of the cold front.  There could be some cirrus clouds around and some high based cumulus clouds in the afternoon.  Look for temps to rapidly soar in the morning and we will be at 74 by noon and upper 70s for a high temp in town.  Fire weather concerns are significant on Tuesday with very low afternoon humidities and gusty winds.  Dont burn anything.   The front passes late Tuesday night but right now the atmosphere appears pretty dry.  I cant rule out a shower but I would not bet on it at this point.

Cory

Continue reading »]]> 845pm Package

Sunday – Sunny to partly cloudy and warmer.  High 70.  Low 36.

Monday  – Definitely dry and very warm.  Westerly breezes of 1o to 20mph develop in the afternoon.  Fire weather concerns are increasing.  High 77.  Low 41.

Tuesday – Dry, windy and very warm during the day. Fire weather concerns are high!!    High 78.    Isolated shower at night with a new cold front?   Low 40.

Extended Forecast:

Wednesday – Cooler, mainly dry and breezy/windy.    High 65. Low 36.

Thursday – Mainly dry and breezy/windy.  High 66. Low 38.

Friday – Dry and breezy, turning very warm.  High 76.  Low 40.

Cory

Continue reading »]]> Well my friends its that time of year again.  I’m a touch early like last year but I have done the research and I figured I might as well let it fly.  Over the last 4 years and I say this with humility….This outlook has be astoundingly close so read this one with understanding.  Remember last years predictions as we tend to forget the past very quickly.  I’m sure some of Y’all chuckled when I said 475″ at Vail and Steamboat and over 400″ at our resorts.  Well my friends last year Vail ended up with 550″ of snow and our resorts had 395 to 440.  Its hard to argue with those totals as the snow is still up there in late July!!

So what are we looking at for the Winter of 2011-2012.  Over the last 4 years the outlooks have been rather easy because 2 of the last 4 winters have been moderate to strong La Nina’s and they are very easy to predict.  La Nina’s bring lots of snow to our region.  The years in between we had a one strong El Nino…El Nino’s also have very predictable patterns associated with them.

I’ll be honest with everybody…About a month ago I thought this winter was going to be ENSO neutral.  ENSO stands for El Nino Southern Oscillation.  When I say ENSO neutral that means in June there was no clear signs of La Nina or El Nino for this upcoming winter.  It also meant that water temps over the equatorial pacific would not stray too far either side of normal.  So I went ahead and compiled a lot of statistics for neutral winters around here.  There were 34 neutral cases since 1935 and the data was not very earth shattereing for around here.  It showed us basically having near to slightly below normal snowfall.

Well back in June when I stated doing statistics for a neutral winter things began to change.  As of now (late July) I have revamped my entire forecast and I will explain why below!!

There is a very very important term out there called the PDO.  PDO stands for Pacific Decadal Oscillation.  Back in the year 2008 we entered a Cold Phase of the PDO.  A cold phase of the PDO means water temps all along and off the entire west coast extending out into the pacific a few hundred miles are below normal.  These PDO events tend to be rather stable and can last for 10 to 20 years at a time.  The most important thing about the cold phase of the PDO is they tend to cause La Nina events.  Remember the epic winter of 2007-2008…That was a moderate to strong La Nina and correlated well with the cold phase of the PDO just developing.  Then once again last year we had another moderate to strong la Nina.  Right now the look of water temps along the west coast and out in the pacific is a classic cold phase of the PDO and low and behold the forecast models are picking up on a developing La Nina yet again.  What alerted me strongly to this new development was the highly talented European model which now has a strong signal toward La Nina this winter.   As a matter of fact all the other bias corrected models are now pointing toward La Nina.  All of this make absolute sense to me given the fact that PDO’s are very stable and Cold PDO’s favor the development of La Nina’s.

So here’s the most important topic about this upcoming winter:  I believe we are once again heading for another La Nina which would make it 3 out of the last 5.  La Nina winters over the central and northern mountains of Colorado are snowier than normal and this statement has much statistical evidence to back it up.  The decision I have to make is how strong will the la Nina be this winter.  Right now current indications are for a weak La Nina with water temps from .7 to 1C below normal.

So now the mission is to look at all the weak La Ninas since 1935 and correlate snowfall amounts to Aspen.  This will give us a sense as to what type of winter is coming based on the past. The data is respectable for weak La Nina’s with about 10 cases.  I also included 3 cases where the la Nina was a very low end Moderate.  Out of this data came an average snowfall in downtown Aspen of about 10% above normal.  This seemed reasonable to me because weak La Ninas definitely have a dominant W to NW flow in the mid levels around here which is good because thats an upslope trajectory.  In Weak La Nina winters the jet often times is near us but peaks just to our north in Wyoming.  This is why snow is a bit better from I-70 northward.   After doing some statistics where some years get assigned a more important value and some years take on less importance based on the current weather scenario I have come up with a decent curve for this years snowfall outlook.  The curve is pretty typical of la Nina’s and reveals that from I-70 North is where the most snow is likely.  The central mountains do well but the best snow is from Vail to Jackson Hole.  There is an extremely strong correlation between the cold phase of the PDO and a coincident La Nina concerning areas to our south.  100% of time is has been very very very dry across New Mexico and Arizona with droughtlike conditions.  My guess for southern Colorado and the San Juans would be for Below normal snowfall.  We all know it dumps in the San Juans like at Wolf Creek and Silverton so Below normal snow there is all relative.

Winter Outlook Snowfall Prediction Totals for 2011-2012:

Lets start with what is normal around here: Normal snowfall in downtown Aspen is about 152 inches with 160 inches at the water plant.  Normal snowfall at the resorts is about 300 inches at AJAX, 318 at Highlands, 328 at Snowmass and 360 at Vail. 

Here are my final numbers for this upcoming winter:

Downtown Aspen – 163″

Resorts:

AJAX – 344″

Highlands-370″

Snowmass – 380″

Vail – 435″

I would think everybody would be pretty happy with this outlook because snow amounts for the resorts are forecast once again to be above average.  This would make 5 winters in a row if I’m right.  5 straight winters with above normal snow has only happened twice before since 1935.  So the moral of the story is I need to keep a close eye on the Pacific in Sept and October and if the models keep going with the weak La Nina trend then these numbers will be close.  Updates later if necessary but I doubt it!!

See ya

Cory