May 5, 2020: May CODOS Tour Observations — Colorado Dust-on-Snow Program (original) (raw)

Greetings from Silverton,

Here in Silverton and much of Colorado it has been pretty much hot and dry for the last couple weeks, this past week especially so (see temperature maps below). In and around town the newly exposed soil is dry and there are very few moist areas like we normally see. We have not had an official storm since Easter (April 12). Since then we have received bits of precipitation adding up to a little over an inch. For the month of April we received 2.3” precipitation, that is over a couple inches short of what we normally receive. The CBRFC noted that a number of SNOTEL’s in Southwest Colorado reported their driest April on record.

This past weekend the CODOS team completed the final CODOS statewide tour of the season. The Central and Southern sites particularly have been melting fast since our last visit three weeks ago. On April 11 for example a 5.2’ deep snowpack with 24.6” SWE at Wolf Creek was 2.8’ deep containing 14.3” SWE on May 1. The snowpack is melting so fast that we collected all-layers-merged samples - usually we do this towards the end of May or in June - for USGS analysis because most sites will be melted out relatively soon.

Dust conditions throughout the state are generally pretty minimal. The Central and Southern sites have obvious dust with the Southern locations edging towards “moderate” dust conditions currently from “light” previously. At Swamp Angel dust event #1, a moderate layer, is 1’ under the surface and will ensure this once merged at the surface. At Wolf Creek all dust layers are merged at the surface, and taken as a whole are severe enough, plus an additional layer only seen in the Southern San Juans, to push current conditions to moderate as well.

The heat with dust on the surface has been rapidly melting the snowpack and spiking streamflows. The forecast unfortunately is more of the same. Tomorrow temperatures will be well above normal and the usual warm and dry the remainder of the week. Gusty winds are also called for over the next few days. In the Silverton area the first chance of precipitation looks to be on Monday/Tuesday. It is not often that the precipitation forecast map is completely blank for the entire state of Colorado (see maps below), but the 5-day map currently is and the 7-day is not showing much forecasted moisture either.