McIDAS images of GOES-15 (GOES-West) 0.63 µm visible channel data (above; click image to play animation) revealed large plumes of blowing dust and sand, which were moving south/southwestward from the coast of Baja California and western Mexico on 16 March 2014. There were no surface observations in the immediate vicinity of the Baja California dust plume source regions, but farther to the southeast at Loreta (station identifier MMLT) winds gusted to 37 knots or 43 mph at 19 UTC (12 Noon local time), and surface visibility was reduced to 3 miles. Surface winds were likely channelled by the upstream mountainous terrain to reach higher speeds near the dust plume source regions.

A comparison of AWIPS images of Aqua MODIS 0.65 µm visible, 1.38 µm “cirrus detection”, 3.7 µm shortwave IR, 11.0 µm “IR window”, and 6.7 µm water vapor channel data at 21:40 UTC (below) showed the following: (1) the dust/sand plume could also be seen on the 1.38 µm “cirrus detection channel” image, since this channel can be used to identify any airborne particles that are effective scatterers of light (such as cirrus ice crystals, volcanic ash, haze, or dust/sand); (2) while there was no obvious dust/sand signal on the conventional IR window channel image, the much warmer (darker black) signature on the shortwave IR image was due to reflection of incoming solar radiation off the dust/sand particles; (3) on the water vapor image, an undular bore appeared to be developing near the leading edge of the dust/sand plume. According to 1-hour interval MADIS satellite-derived atmospheric motion vectors (green wind barbs), the plumes were moving toward the southwest at speeds as fast as 25 knots at the time.

Metop ASCAT surface scatterometer winds (cyan wind barbs) at 17:43 UTC (below) indicated that winds were northeasterly at speeds around 20 knots just off the western coast of Baja California; 18 UTC GOES-15 satellite-derived winds (green wind barbs) tracked the southwestward motion of the dust plumes at speeds of 20-31 knots.

A sequence of true-color Red/Green/Blue (RGB) images from Terra MODIS, Suomi NPP VIIRS, and Aqua MODIS viewed using the SSEC RealEarth web map server (below) showed the southwestward progression of the tan-colored dense plumes of airborne dust/sand from Baja California. In the initial Terra MODIS image, the source region of many of the plumes appeared to be near the El Vizcaíno Biosphere Reserve.

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In their Area Forecast Discussion issued at 11:57 UTC or 4:57 AM local time on 14 March 2014, the NWS San Francisco/Monterey Bay Area forecast office mentioned the Suomi NPP VIIRS Day/Night Band imagery which showed the coverage of coastal fog in their area of responsibility:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
457 AM PDT FRI MAR 14 2014

.DISCUSSION...AS OF 4:10 AM PDT FRIDAY...THE DRY TAIL END OF A
WEATHER SYSTEM MOVING IN TO THE PACIFIC NORTHWEST IS APPROACHING
OUR DISTRICT...AND RESULTING IN ENHANCEMENT OF THE MARINE LAYER
AND A RETURN OF THE MARINE STRATUS. LATEST GOES FOG PRODUCT
IMAGERY...AND IN RATHER SPECTACULAR DETAIL JUST REC`D SUOMI VIIRS
NIGHTTIME HIGH RES VISUAL IMAGE...SHOW COVERAGE ALONG MUCH OF THE
COAST FROM PT REYES SOUTH TO THE VICINITY OF THE MONTEREY
PENINSULA...AND A BROAD SWATH EXTENDING INLAND ACROSS SAN
FRANCISCO AND THROUGH THE GOLDEN GATE TO THE EAST BAY. LATEST
BODEGA BAY AND FT ORD PROFILER DATA INDICATE A MARINE LAYER DEPTH
OF ABOUT 1300 FT. SOME THIN HIGH CLOUDS ARE ALSO PASSING THROUGH ABOVE.

A comparison of AWIPS images of the Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) and the corresponding 11.45-3.74 µm Infrared brightness temperature difference (BTD) “fog/stratus product” (below) showed this band of fog and stratus at 09:39 UTC or 2:39 AM local time. With ample illumination from the Moon (which was in the Waxing Gibbous phase, at 97% of full), the DNB image served as a “visible image at night” to help highlight the fog/stratus features along the coast. Farther inland over the eastern portion of the satellite scene, the bright signature of deep snow cover in the higher elevations of the Sierra Nevada was also very evident on the DNB image.

A sequence of three Infrared BTD images (below) — Terra MODIS at 06:33 UTC, Suomi NPP VIIRS at 09:39 UTC, and Aqua MODIS at 10:44 UTC — offered detailed views of the inland progression of the fog/stratus features, especially in the San Francisco Bay area and also down the Salinas Valley. The appearance of degraded resolution of the features seen on the 10:44 UTC MODIS image is due to the so-called “bow-tie effect” near the edge of a MODIS scan swath — even with a bow-tie correction algorithm applied, the MODIS images tend to look less crisp and clear along the scan edges.

A GOES-R “Cloud Thickness – Highest Liquid Cloud Layer” product created using GOES-15 data (below) showed the southward advancement of the band of fog/stratus during the overnight hours. The maximum thickness displayed was in excess of 1200 ft (lighter cyan color enhancement), which agreed well with the profiler depths mentioned in the NWS forecast discussion above.

Additional GOES-R products such as Marginal Visual Flight Rules (MVFR), Instrument Flight Rules (IFR), and Low Instrument Flight Rules (LIFR) Probability are shown below. These products help to better quantify the potential aviation impacts that features seen on the conventional BTD “fog/stratus product” might have.

For additional information on this event, see the GOES-R Fog Product Examples blog.

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AWIPS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) show the hazy signature of an intense dust storm (sometimes locally referred to as a “haboob”) created by strong winds in the wake of a southward-moving cold front on 11 March 2014. This blowing dust reduced surface visibility to zero in parts of southwestern Kansas (where there were wind gusts of 59 mph), causing several traffic accidents. At Amarillo, Texas (KAMA) the wind gusted to 60 mph, and visibility was reduced to 0.25 mile at times. A pilot report indicated that the top of the blowing dust was as high as 11,000 feet over the Oklahoma panhandle region.

A sequence of Terra/Aqua MODIS and Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images visualized using the SSEC RealEarth web map server (below) showed the southward advancement of the lighter tan colored areas of blowing dust.

A signal of the airborne dust (cyan color enhancement) was also seen on Terra/Aqua MODIS images of the 11-12 µm “reverse absorption” IR difference product (below).

GOES-13 6.5 µm water vapor channel images (below; click image to play animation) showed the development of a “cirrus bloom” over far northeastern New Mexico as the surface cold front and blowing dust moved through that region. It is interesting to note that there was a pilot report of severe turbulence at an altitude of 45,000 feet around that time (reportedly due to a mountain wave) — this raises the question as to whether a vertically-propagating wave generated by the strong cold front might have caused that high-altitude turbulence.

Additional satellite images of this event can be found on the Wide World of SPoRT blog.

===== 12 March Update =====

During the subsequent night-time hours, a Suomi NPP VIIRS 0.7 µm Day/Night Band image at 08:35 UTC or 2:35 AM local time (above) displayed a signature of the airborne dust over far southwestern Texas — the glow of the city lights below the dust layer was more diffuse than in dust-free areas farther to the east in central Texas. Also note that an undular bore had formed along the cold frontal boundary near the coast of southeast Texas.

A comparison of the VIIRS Day/Night Band image with a MODIS 11-12 µm image (below) confirmed the presence of airborne dust over southwestern Texas. As in the MODIS example above, the brighter cyan color enhancement was a signal of dust.

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A night-time AWIPS image comparison of Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band data (above) showed a large mesoscale convective system (MCS) over the Gulf of Mexico at 07:08 UTC (2:08 AM local time) on 06 March 2014. On the IR image, brightness temperatures were as cold as -80º C on the far southern end of the storm, which had developed in the warm sector of a developing area of low pressure (surface frontal analysis). The Day/Night Band image revealed: (1) numerous bright west-to-east oriented “lightning streaks” caused by intense lightning activity illuminating the MCS cloud and cloud top — note that there were over 1300 cloud-to-ground (CG) lightning strikes detected in a 15-minute period, and (2) arc-shaped mesospheric airglow waves propagating northward and northeastward away from the region of vigorous overshooting tops at the southern end of the MCS.

A comparison of the 375-meter resolution Suomi NPP VIIRS 11.45 µm IR image with a 4-km resolution GOES-13 10.7 µm IR image (below) showed that the higher spatial resolution of the VIIRS data provided much clearer view of the various cloud structures along with a better depiction of the values of the cloud-top IR brightness temperatures.

GOES-13 10.7 µm IR channel images (above; click image to play animation) showed the evolution of the MCS as it continued to move eastward toward Florida. A squall line developed along the leading edge of the MCS, which played a role in producing a few tornadoes and areas of damaging winds over the southern half of the Florida peninsula (below).

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