Thursday, January 20, 2011

Jan. 20 - Breezy early in the morning but calm during the day. The morning low at the NMSU coop site was 33F, 46 at the Las Cruces airport, and 47 in Deming. The 33 appears low but the climate center's low temperature reading low was 35.4F. The coop sensor is about 10 feet away from the climate center's sensor. The low at the Dripping Springs RAWS was 42F this morning. So this points toward a temperature inversion since the airport and RAWS stations are at higher elevations. Actually the low is going to be in the late evening since it's already in the 30s at 10 pm. The plot below shows predicted surface winds at 18 UTC (11 am) today.
The weather map shows the location of front at 18 UTC and corresponds to the higher surface wind speeds over northern Chihuahua.
It will start to cool off after a cold front slides through the region this afternoon. Particulates at the core site showed nothing out of the ordinary with a peak PM2.5 of 47 µg/m3 at 11 am.
We saw a brief wind erosion event a the Sunland Park City Yard station this morning.
Good air quality at the Las Cruces Holman Road station.
A prescribed burn in the Coronado National Forest looked to bring in a little smoke (green shaded area) into Hidalgo County today. The fire is on the west slopes of the Chiricahua Mountains burning about 750 acres of grass and brush today. The spot forecast called for light southeast (coming from SE) winds at 20-foot. The smoke plume however is entrained in the winds aloft that carries it eastward.
At 00 UTC (5 pm) winds aloft at 700 mb (about 10,000 ft above sea level) were from the west as the map below shows. Wind streamlines in this map were from the 00 UTC run of the NAM model at 80-km.
We observe this decoupling of the lower boundary layer with the free troposphere in the 00Z sounding at Santa Teresa. The base of an inversion is around the 700 mb pressure level and above that is a very dry layer with a mixing ratio down to 0.05 g/kg that is 50X less than at the surface.
One last point I'll make on this frontal event is to show the Deming radar wind profiler wind ladders for today. You can see the drastic wind shear and veering of the surface winds compared to those aloft. The break is right around a height of 2.5 km above sea level or about 1.2 km above the ground. This is what makes it so much fun.

Time lapse camera from NMSU shows our clear skies after a cloudy morning. You can see the winds are from the west at the cloud level.
video

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