This content was originally published by the Longmont Observer and is licensed under a Creative Commons license.
Forecast Discussion:
We looked at the upper air patterns yesterday. Now let's get into the details. With gusty down slope winds and warming from the ridge side of the jet stream, we'll crack temperatures above 60F today. Starting tomorrow, odd and unpleasant things begin to happen...
Figure 1 is the 10 day graphical look (and precipitation ensemble) for Denver. The National Weather Service expects the Friday temperatures to be much lower than the models are predicting (so I drew a downward pointing blue arrow on Friday). With some up slope flow and that very thin and very cold air, we might see periods of ice and freezing drizzle on Friday into Saturday morning.
Figure 2 shows how warm the air is above normal on Thursday (today). Figure 3, for Friday, shows the shallow cold air coming in colored blue. Expect that to push up into the lower foothills further west than depicted here. Friday might be a difficult day to get around.
Figure 4, for Saturday, shows the cold air at near maximum invasion. It should be thick enough for a change to snow (still very light snow) for the weekend.
The longer range forecast:
Saturday's storm has not completely vanished from the forecast yet... the GFS paints us in the 1-2" area for earlier and midday Saturday - Figure 5.
Back to Figure 1 - we return to normal-ish temperatures by Monday then the next system moves in. Most model runs do give us snow on Tuesday. We'll wait until after the Saturday storm to put numbers on this one though.
