New Mexico Snow Event – SFR Assessment

An upper level low tracking over Arizona bought widespread rain and snow to New Mexico on January 13 and 14, 2015.  For this post, we will focus on the area from west central to central New Mexico.  A winter storm warning was issued for the higher terrain of western and central New Mexico with advisories posted for lower elevations. Originally, the Albuquerque Metro area zone was not included in the advisory, but on the afternoon of January 13th, the advisory was expanded to include the Albuquerque Metro area zone as snow was expected to impact the morning commute.

The image below shows the  6-h precipitation forecast for 06Z-12Z on 14 January from the 00Z run of the NAM12. Precipitation was forecast to focus on the area along and north of Interstate 40 from west of the Arizona border near Gallup, past Grants and just into Bernalillo County but west of Albuquerque, with another active area south of Albuquerque.

NAM12_Precipitation_Img_20150114_1200F006cr2

Several interesting features are illustrated in the next image – a comparison of the NESDIS Snow Fall Rate Product and 8-bit 0.5 Reflectivity from KABX near 09Z. The projections are slightly different, but the dashed line shows an area of somewhat enhanced snow fall rates from the NESDIS product and both Window Rock (KRQE) and Gallup (KGUP) are reporting snow. Note how the radar returns decrease in the same area, which is only covered by KABX.  Extreme western New Mexico, including the Four Corners area, has poor radar coverage, with the 0.5 scan over 11,000 feet AGL at KGUP. To the east along I-40, Grants (KGNT) is not reporting precipitation, while Albuquerque is reporting rain. Thus, the SFR product appears to accurately define the area of snow, though reports for the area north of I-40 are difficult to obtain, especially during the overnight hours.  By the afternoon, totals for the area along and north of I-40 ranged from 2 in to 12 in.

SFR/Z Comparison 09Z

The MODIS-VIIRS Nighttime Microphysics image depicts both the enhanced mid level clouds associated with snow (orange to red) and the low clouds (light pink/light green) impacting other areas of western and central New Mexico.

MODIS-VIIRS_NTmicro_20150114_0904cr

Moving two and one half hours forward, another SFR/0.5Z comparison is shown below.  Stations along Interstate 40 (KGUP and KGNT) are still reporting snow as are stations south of Albuquerque (KE80 and KONM), though snowfall coverage in the SFR product was reduced in both intensity and area. The radar image is focused on the greater Albuquerque area, or the locations within the white box on the SFR product. At this time, KABQ was reporting east winds gusting to 23kt. Gap winds through Tijeras Canyon (east of Albuquerque) have a downslope component of 1200 ft, often resulting in a snow-free zone around the Albuquerque metro area. The pink dashed line depicts the approximate edge of the precipitation-free area,  with the beam blocked area also evident further to the east. For this area, the SFR product indicates snow to the west and south of Albuquerque, verifying the observations.

SFR/Z Comparisons1130Z

The east gap winds relaxed and snow soon moved into the Albuquerque Metro area, with snow reported at KABQ at 1209Z. By 1313Z, conditions deteriorated with visibility of one-quarter mile in snow, and the airport picked up a quick inch of snow in just over an hour, with 1-2 inch amounts elsewhere. Thus, the winter weather advisory for the Albuquerque zone verified, and impacts during the start of the morning commute period resulted in a 2-hour school delay.

20150114_061429cr

One thought on “New Mexico Snow Event – SFR Assessment

  1. This is an outstanding post! I’m very glad that the SFR product was able to depict snow that was shown in your areas of radar coverage appropriately and help in the radar void regions.

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