GOES Low Cloud and Fog Depth Analysis in Complex Topography

Several widespread moderate to heavy snowfall events across New Mexico during late January 2010 lead to several periods of low clouds and fog.  This particular case shows the high resolution detail provided by the low cloud base and combined fog products within the 60 mile extent of complex terrain between Albuquerque and Santa Fe.

Left image is GOES 4km Low Cloud Base and right image is Combined Fog Product 01/30/10 valid 0615Z

Notice the green shading over Albuquerque, indicating that low cloud base detection is greater than 1000 feet.  The red shading over Santa Fe indicates that low cloud base detection is less than 1000 feet.   The observations at both sites support the GOES low cloud base product:

KABQ 300256Z 20004KT 10SM FEW030 SCT045 SCT150 00/M04 A3011
KABQ 300356Z 00000KT 10SM FEW030 BKN042 M01/M03 A3011
KABQ 300456Z 00000KT 10SM FEW030 OVC042 M01/M04 A3011
KABQ 300556Z 00000KT 10SM FEW028 OVC040 00/M03 A3011

KSAF 300253Z 00000KT 10SM OVC009 M01/M03 A3008
KSAF 300435Z AUTO 33003KT 9SM OVC003 M02/M03 A3008
KSAF 300518Z AUTO 32005KT 3/4SM BR OVC001 M02/M03 A3009
KSAF 300618Z AUTO 34005KT 1/4SM FZFG VV001 M03/M04 A3009

The Combined Fog Product on the right indicates that along with the low clouds we should see areas of fog. In fact, the KSAF observation is carrying one quarter mile visibility.   The area around KABQ in the combined fog product indicates a large area of fog depth near 400m. However, no fog was observed at the site all night.  It should be noted that the combination of low clouds detected less than 1000 feet and the presence of depth values in the combined fog product has shown a much better correlation than for low cloud bases detected greater than 1000 feet. This has been noted by several forecasters.

Left image is GOES 4km Low Cloud Base and right image is Combined Fog Product 01/30/10 valid 1015Z

Low clouds and fog continued to develop across the region through the predawn hours.  The observations at both sites support the strong contrast in low cloud ceiling height between Albuquerque and Santa Fe.

KABQ 300756Z 00000KT 10SM SCT030 OVC040 01/M03 A3012
KABQ 300856Z 00000KT 10SM SCT028 OVC037 01/M03 A3012
KABQ 300956Z 00000KT 10SM FEW025 OVC037 01/M03 A3011

KSAF 300833Z AUTO 33006KT 1/2SM FZFG VV001 M04/M05 A3009
KSAF 300950Z AUTO 00000KT 1 1/4SM BR OVC001 M04/M04 A3008
KSAF 301035Z AUTO 35003KT 1/2SM FZFG OVC001 M04/M05 A3008

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