San Juan Mountains Weather Report Monday, January 23, 2012–13:30
My last forecast posted 2 days go ended with the conundrum of three computer models lacking agreement in solution. Now with the clarity of the immediate future it looks like the last model that called for a split flow, combined with the first model which called for snow beginning tonight has become today’s forecast. By late afternoon we should see snow flurries beginning and increasing throughout tonight and early tomorrow with up to a foot of new powder for the mountains above 11,000′.
There was good upstream moisture in the low pressure trough when it moved onshore at daybreak. As it moves through the Great Basin it will split with a southern low over SE New Mexico on Tuesday, but will remain whole enough as it travels into the forecast area to bring much needed precipitation, but without the power of the last storm. Lacking strong winds, orographics and weakness because of the splitting, it will favor the southern portion of the San Juans as the southern branch passes near the 4-corners. Remember SW flow does not favor the N side of the SJ’s unless it’s a Major storm….
Because of warm air temperatures there will be rain/snow mix early especially in the lower valleys then with elevation and cooling evening temperatures snow will kick in. SSW facing slopes will see the highest amounts in the San Juans. The snow will begin to diminish from the west early on Tuesday as the flow splits and a drier ridge of high pressure develops with NWesterlies. Clearing and stable atmosphere will remain in place until the next wave enters the area by Friday with a chance of precipitation, but right now doesn’t look very juicy. The future looks to be drying out again with shortwave ridging into the weekend. Temperatures want to remain above seasonal norms for the period.