Click Below if you want to see the Winter Outlook.
Tuesday's De-brief - The trough we had yesterday was pathetic as it split. The splitting of the trough left us high and dry, we had very minimal if any snowflakes. It stayed cloudy for a while early to mid morning then the sun came back. PM mixing was a little better and high temps averaged between 38 to 42 from Aspen to Basalt.
Quick Forecasts for Today (Wednesday):
Aspen to Basalt: Thickening clouds. Snow gets started a bit later this afternoon and continues the first half of tonight. 2 to 4" in Aspen by late tonight, 1 to 2" near Basalt. High 34/35 Aspen, 36/37 Basalt. Wind becoming NW 9 to 18mph with a few gusts. Skies become P/Cloudy late tonight. Cold with lows 4 to 9.
On-Mtn: Thickening clouds. Snow gets started this afternoon and continues the first half of tonight. 3 to 6" by late tonight. Highs in the low to mid 20s at mid-slope and 11K, temps will be falling by late day. Wind becoming NW 12 to 22mph with a few gusts.
Today (Wednesday)....Updated 630am - So as usual I'm looking at the water vapor loop early this morning. All the global models did a good job initializing today's upper air system, their solutions seem quite realistic. I'm not going to make any changes.
So here's the deal. A good blob of mid and high level energy will invade our region this afternoon into tonight. Based on the water vapor loop, this blob of energy has strong mid-level vorticity and good high level divergence at jet level. This system has a thermal profile that cools rapidly as we get a bit later in the day. So even though the valleys get above freezing today, it will make no difference whatsoever as it will snow. Cloud physics continue to indicate saturation at mountain top, temps are cold enough in the saturated air mass for nice 'Stellar Dendrites' or fluff. Our wind profile is upslope W at 40 to 45mph most of the day, by late day it goes upslope NW and stays that way tonight. Instability still looks good with values above the benchmark of 7C/Km, we could get a few bursts of snow as stronger radar echoes mix in.
Summation, so today we have Top Down Saturation or TDS. This means it saturates up higher first and gradually works its way down to the valleys. So this afternoon it be a classic looking snow sky, then you will look up and see the higher elevations becoming obscured, then the saturation and snow will get to the valleys a little later. I'll stay with 3 to 6" at the ski areas by dawn Thursday. I'll also stay with 2 to 4" as one gets near Aspen. A general 1 to 2" could happen down valley. Lastly, I think some instability bursts will happen, the snow amounts given above are averages, a little more or little less will happen depending on who gets the bursts. That's just how it is!!
Thursday (Updated 630am) - I have no changes for Thursday as our atmosphere is strongly subsident. Subsident means our air mass will be sinking. Strong subsidence helps to build surface pressures and I think we will be around 1034mb all day, this is pretty high. A cold surface high limits low level mixing and it will be a cold day. I still like mid 20s around Aspen.
Thursday night our temps will plummet after sunset under mostly clear skies. There might be just enough warming in the mid levels overnight that we don't get super cold. I will stay with numbers that are below guidance, I'll go a cold -2 to 5 above from Aspen to Basalt.
Friday (Updated 630am) - Ridging aloft will dominate so expect dry weather with a decent amount of sun. Temps will be cold early in the morning and surface pressures will remain rather high all day. Valley inversions will definitely be present as warming temps aloft strengthen the low level inversion. I envision Friday as a day where it's warmer at 11K than it is in Basalt. Mid 30s look most likely for the valleys, as usual the sheltered areas down valley could stay colder.
Extended Forecast (Sat-Mon 12/15-12/17):
Saturday - There will probably be a period of weak upper air support during Saturday. Our air mass looks pretty dry in the low level so I will keep conditions dry. Sure there might be a morning flake but it won't be anything important.
Sunday - I think ridging aloft will be dominant and I like dry weather for our region. Sunday is potentially a mild day but I think mixing will be poor, this means the valleys probably won't get overly warm.
Monday - A new California system might get pretty close but most all the global models are not impressed with this system. My guess is we experience some mid and high clouds. I'm in no hurry to introduce precip when we are in Phase 4 of the Madden Julian Oscillation (MJO).
Aspen Airport Extended Temps:
Next Week - Remember we are in Phase 4 of the MJO. This is not a good Phase for us due to latent heat being released over the SE Indian Ocean and S Pacific. At the moment, I don't have any compelling reasons to introduce snow next Tues/Wed/Thur. It's likely a dry and mild period.
So let's look at this way. This Thursday 12/13 will be dry, I think we stay mainly dry through next Thursday which is 12/20. So right now after the snow we get today/tonight, at least 8 days in a row will be dry after that.
Beyond 12/20 is difficult, my tele-connection analysis so far this Fall has worked, even to the exact day a few times 12 days in advance. I cannot get a complete grasp on 12/20 to 12/31 yet because the MJO is screwing things up. My guess after 12/20 is the MJO loses a ton of amplification and just shuts off. That would open the door in our area for action around 12/21 and beyond, the reason why is when the MJO shuts down, all the convection and latent heat release in the SE Indian Ocean goes away.