Wednesday, April 6, 2011

April 6 - Breezy afternoon and dust in early evening

The day started with clear skies and fairily calm winds. An approaching upper level trough is expected to be over us starting today. Looking at the upper level maps at 12Z the cut-off low is off the coast of Baja California and expected to move east and dampen out. Another low from the Pacific Northwest is also expected to move down the coast and deepen over the next few days. That will be our weather pattern at least through the end of the week. At least for today I'm not seeing surface dewpoints rise until 06 UTC tonight (midnight) but there looks to be more moisture aloft based on the approaching cloud cover that I'm seeing on the GOES satellite. This will affect our chances for any precipitation on the ground.

Below are the southwesterly winds we expect to see this afternoon at 00 UTC (6 pm MDT).
Based on what I'm seeing I'm not expecting any precipitation to fall on our dust sources so I'm going to forecast some wind blown dust this afternoon. Probably late into the afternoon and into the evening.The NWS forecast discussion mentioned that any precipitation that falls will probably be evaporated before it hits the ground because of the dry air mass near the surface.

Today's AQI forecast is calling for an area of moderate air quality over West Texas and the Paso del Norte.
Cloud cover moved in over the border area in the afternoon. By 4 pm I was seeing virga looking out toward the west from NMSU. This photo was taken 4:52 pm toward Pichacho Hills.
Below are ceilometer backscatter plots from today showing the virga. The clouds ranged from 5 to 6 kilometers above the ground. Virga can be seen as the red lines reaching toward the ground. The first plot shows backscatter from 3 to 6 pm
Then from 6 pm to 9 pm
Then from 9 pm to midnight
Although we did not get measurable rain at the site it looks like there was some very light precipitation on and off from 6:30 to 7:00 pm and around 11:45 pm.

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