Impacts from the Silver fire were substantial over Las Cruces today as winds were light and tended to follow the terrain. Below are wind streamlines at 8 am Wed. that show wind patterns causing the smoke to fill in the valley this morning. The streamlines point toward the southeast from the fire, draining toward lower elevation and along the Rio Grande.
Most of the smoke was elevated in the morning and above the shallow temperature inversion. The photo below was taken about 8:30am looking toward the Organ Mountains with the smoke thickest about half way up the slopes.
Yesterday we saw some smoke drifting in from the Silver fire and lift by evening. Below are hourly measurements of PM10 (blue line) and PM2.5 (red line) collected at the Fabian Garcia Horticulture farm on campus in Las Cruces. As of noon the Organ Mountains 10 miles away are obscured by the smoke from campus. As of 1:30pm the Las Cruces airport was observing 7 mile visibility. Below are the PM10 and PM2.5 concentrations at the NMSU Las Cruces campus as of 9 pm.
We took a PM10 filter sample today to analyze particle morphology in addition to getting a mass concentration to compare with the continuous sampler. We ran the BGI PQ100 for just under 12 hours and also collected particles on a nuclepore filer for analysis with the electron microscope. Below is a representative image from the nuclepore filter during the smoke event today. Many of the particles looked similar to this one. I think this is a soot particle made up of many smaller monomer strands. Physical diameter was on the order of 10 microns. There were also particles that looked geological in nature and a few biological particles.
This morning the smoke was kept aloft above an inversion over Las Cruces. The CL31 ceilometer running as a backscatter lidar clearly allows us to visualize that. I highlighted the top of the layer when the backscatter signal was high starting around 5 am. By 11 am the smoke started to mix down toward the ground as the inversion broke up and caused PM2.5 concentrations to increase rapidly.
The forecast for smoke for Wednesday and into Thursday is for more impacts of the Silver fire in the area around the fire to include Las Cruces as shown in the map below.
I'm more concerned about the overnight smoke concentrations and early morning. The NOAA smoke forecast guidance maps show smoke settling in the Rio Grande valley and potentially causing high PM2.5 concentrations on Thursday morning, June 27. If you live in the area with shading, I would make sure your windows are closed tonight and turn off your swamp cooler if you have one.
Forward trajectories from the fire overnight are supporting this forecast. The trajectories in the map below are from the RAP 20km model run with a Hysplit ensemble at 500m starting height from 04Z to 21Z.