Monday's De-Brief: Yesterday we had snow showers in the morning with broken to overcast strata cumulus clouds. During the afternoon strata cumulus clouds were mainly broken with intervals of sun, I saw a few flakes in the PM but it was no big deal. The ski areas got a half to one inch in the AM, down valley also had another inch, Aspen had a bit too.
Quick Forecast for Today (Tuesday):
Aspen: Variable clouds. High 41 Aspen, 44 Basalt. Wind NW 10 to 20mph. Low tonight 22 to 27.
On-Mtn: Variable clouds. High 28 at mid-slope, 24 near 11K. Wind NW 12 to 22mph, stronger speeds above 11K.
Today (Tuesday)...Updated 600am - Today we have a NW upslope flow. Within this NW flow we are going to experience weak warm advection aloft along with small pieces of mid-level energy. The sky cover for today is tricky because weak warm advection into an upslope wind is dangerous. The little bits and pieces of mid-level energy are also problematic.
What I think happens is we end up with a fair amount of strata cumulus clouds, there also will be some cirrus later this afternoon. I'm going to call our sky cover variably cloudy. Variable clouds means that yes some pockets of sun could occur, it also implies that much of the time we have 7 tenths or more of the entire sky covered. Overall it looks like a mainly dry day, I think some snow showers will happen north of here. I can't rule out a few flakes in our area but it does not look significant.
Wednesday (Updated 600am) - Ridging aloft arrives on Wednesday but our air mass will probably not be clean. As the ridging aloft arrives our ambient water will be increasing at the same time. I believe this will lead to mid and high clouds and eventually some strata cumulus clouds. I'm going to call our sky cover variably cloudy once again, could there be some intervals of sun before the day is over, of course. Lastly, I can't rule out a rain or snow shower as this scenario unfolds.
Thursday (Updated 600am) - Thursday will be a huge challenge and I'm going to make significant changes.
Our flow aloft turns SW, this fact will allow ambient water to increase as juice comes surging NE from Southern California. I think we get to 5G/Kg during the day and between 4 and 5G/Kg at night. OK so here's something everybody needs to understand, ambient water means nothing unless one has vertical motion to release it. Our air mass will be very warm on Thursday and we don't have much upper air support. The warm air mass in place will be able to hold all the ambient water without releasing it. Moral of this story, I'm going to keep the daylight hours mainly dry. Look for PM temps in Aspen to shoot up to 60 as balmy pacific air arrives.
The challenge comes at night trying to figure out if we get enough vertical motion to release the ambient water. Trends from the models are important, last night's new trend was to have upper air support come slower. This means I will lower snow amounts at the ski areas by a lot, I'm now going to say 1 to 2" by dawn Friday. The valleys will likely not need to worry about snow as it's too warm, if anything happens it would be rain showers. I may need to tweak this forecast daily my friends so stay tuned.
Extended Forecast (Fri-Sun 3/23-3/25) - The global models and their ensembles agree on Friday. A chunk of energy arrives from California and lifts our ambient water during the day and early evening. This will cause bouts of precipitation. I'm going to leave 3 to 6" at the ski areas. I'm not going to go more than 3 to 6" for many reasons and I'll give ya a few. Our air mass is warm aloft and inefficient, this creates low snow to water ratios. Our wind is also SW all day, Y'all already know how a downslope SW wind can mess things up.
In terms of the valleys, it's not a big event because it's too warm. Yes there could be some wet snow mixed in around Aspen, sticking potential would still be poor. Late day and early evening it gets cold enough to snow so I'll monitor that potential.
Right now I would say that Saturday and Sunday are difficult. There was trend established last night for Saturday, the trend was for very little snow as systems aloft are slower. The GFS model snows nicely on Sunday, the European model waits until Monday. All this additional info needs to be clarified with new upper air data, I'll just wait another day before I put snow amounts in the 6 day snow forecast.