Tuesday, January 25, 2011

Jan. 25 - Low wind high PM episode - We knocked a couple of degrees off of the morning low compared to yesterday. The NMSU low was 24F. Our normal low at NMSU for today is 29F. It looks like the LC Airport low was 23F and 22F at the Deming Airport. High at NMSU was 53F about 6.6F degrees below our normal for this day. Looking at the winds this morning we can see the RUC model shows some downslope and downvalley wind patterns. The map shows surface wind streamlines is for 13 UTC (6 am) this morning. I highlighted some examples of the wind flows from higher to lower terrain wind flows. It's not perfect but it captures some of the basic flow from the most significant terrain.
The afternoon winds are predicted to be low and out of the south. The 21 UTC (2 pm) surface wind forecast is shown below. It just looks like surface wind divergence from a high pressure center over Chihuahua. With low winds we could have some pollutant build-up in a few of our areas.

Our Air Quality Index (AQI) forecast for the Paso del Norte is for an area of moderate. It makes sense with the current weather forecast for today.
As expected we have a low wind high PM episode in the PdN. The Sunland Park City Yard site peaked in the evening.
At the NMSU core site we see morning peak about the same time as in Sunland Park but in the evening we saw a lot less particulates.
I looked a little deeper in the OMI NO2 product image for today. Based on what I read the satellite flyover is around 13:30 local time. I plotted the RUC 21 UTC (2 pm) surface wind fields with the tropospheric NO2 and it remarkably looks reasonable. Based on the northeasterly winds I would expect the NO2 cloud to be southwest of the Paso del Norte urban area and that is pretty much is what you see below.

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