Sir Ivan Fire pyroCumulonimbus in New South Wales, Australia

February 12th, 2017

Himawari-8 0.64 µm Visible (top), 3.9 µm Shortwave Infrared (middle) and 10.4 µm Longwave Infrared Window (bottom) images [click to play animation]

Himawari-8 0.64 µm Visible (top), 3.9 µm Shortwave Infrared (middle) and 10.4 µm Longwave Infrared Window (bottom) images [click to play animation]

Himawari-8 Visible (0.64 µm), Shortwave Infrared (3.9 µm) and Longwave Infrared Window (10.4 µm) images (above / MP4 ; zoomed-in over fire source region: GIF / MP4) showed wildfires burning in New South Wales, Australia on 12 February 2017. The larger Sir Ivan Fire near Dunedoo produced a pyroCumulonimbus (pyroCb) cloud, which first cooled below the -40ºC Longwave Infrared brightness temperature “pyroCb threshold” at 0530 UTC (-47ºC) and quickly reached its minimum temperature of -56.6ºC at 0540 UTC. An animation of Himawari-8 true-color images is available here (courtesey of Dan Lindsey, RAMMB/CIRA).

Consecutive true-color images from Suomi NPP VIIRS (0402 UTC) and Aqua MODIS (0405 UTC) viewed using RealEarth (below) showed the large smoke plume about 1.5 hours prior to pyroCb development.

Suomi NPP VIIRS and Aqua MODIS true-color images [click to enlarge]

Suomi NPP VIIRS and Aqua MODIS true-color images [click to enlarge]

A high fire danger was well-anticipated across this portion of Australia:

Some ground-based photos of the pyroCb cloud:


Northeast US winter storm

February 9th, 2017

GOES-13 Water Vapor (6.5 µm) images, with surface fronts and MSLP pressure [click to play animation]

GOES-13 Water Vapor (6.5 µm) images, with surface fronts and MSLP pressure [click to play animation]

A strong winter storm impacted much of the Northeast US on 09 February 2017, dropping up to 24 inches of snow in Maine and producing wind gusts of 70 mph in Massachusetts (WPC storm summary). GOES-13 (GOES-East) Water Vapor (6.5 µm) images with surface fronts and Mean Sea Level Pressure (above) showed the rapid intensification of the mid-latitude cyclone.

GOES-13 Visible (0.63 µm) images, with hourly surface weather symbols [click to play animation]

GOES-13 Visible (0.63 µm) images, with hourly surface weather symbols [click to play animation]

GOES-13 Visible images (above) and Water Vapor images (below) with hourly surface weather symbols revealed the extent of thunderstorms in the south and heavy snow in the north. A number of sites in New England also reported thundersnow.

GOES-13 Water Vapor (6.5 Âm) images, with hourly surface weather symbols [click to play animation]

GOES-13 Water Vapor (6.5 Âm) images, with hourly surface weather symbols [click to play animation]

Suomi NPP VIIRS Visible (0.64 µm) and infrared Window (11.45 µm) images (below) provided a high-resolution snapshot of the storm at 1708 UTC. Note the areas of banded convective elements both south of the storm center over the Atlantic, and also inland over parts of New England.

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with surface fronts and MSLP [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with surface fronts and MSLP [click to enlarge]

===== 10 February Update =====

Terra and Aqua MODIS false-color RGB images [click to enlarge]

Terra and Aqua MODIS false-color RGB images [click to enlarge]

As the storm moved northward over Newfoundland and Labrador in eastern Canada on 10 February, a toggle between Terra (1601 UTC) and Aqua (1743 UTC) MODIS false-color “snow/cloud discrimination” Red/Green/Blue (RGB) images (above) showed the extent of the snow cover (darker shades of red), although supercooled water droplet clouds (shades of white) persisted over many areas at the times of the 2 images. Glaciated ice crystal clouds also appeared as shades of red.

Snowfall totals in the Canadian Maritimes were as high as 38 cm (15 inches).


Tule fog in California

January 31st, 2017


The tweet shown above was issued by the NWS forecast office in Hanford, California — using an image of the GOES-15 Low Instrument Flight Rules (LIFR) Probability, a component of the GOES-R Fog/low stratus suite of products — to illustrate where areas of dense Tule fog persisted into the morning hours on 31 January 2017.

AWIPS II images of the GOES-15 Marginal Visual Flight Rules (MVFR) product (below) showed the increase in areal coverage of Tule fog beginning at 0600 UTC (10 pm local time on 30 January); the fog eventually dissipated by 2030 UTC (12:30 pm local time) on 31 January. Note that Lemoore Naval Air Station (identifier KNLC) reported freezing fog at 14 UTC (their surface air temperature had dropped to 31º F that hour). In addition, some of the higher MVFR Probability values were seen farther to the north, along the Interstate 5 corridor between Stockton (KSCK) and Sacramento (KSAC) — numerous traffic accidents and school delays were attributed to the Tule fog on this day.

GOES-15 MVFR Probability product [click to play animation]

GOES-15 MVFR Probability product [click to play animation]

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GOES-15 MVFR Probability and Aqua MODIS Infrared Brightness Temperature Difference (BTD) products [click to enlarge]

GOES-15 MVFR Probability and Aqua MODIS Infrared Brightness Temperature Difference (BTD) products [click to enlarge]

Legacy infrared Brightness Temperature Difference (BTD) products are limited in their ability to accurately detect fog/low stratus features if high-level cirrus clouds are present overhead. This is demonstrated in comparisons of GOES-15 MVFR Probability and BTD products from Aqua MODIS (above) and Suomi NPP VIIRS (below). Again, note the Interstate-5 corridor between Stockton and Sacramento, where the extent of the fog was not well-depicted on the BTD images (even using high spatial resolution polar-orbiter MODIS and VIIRS data).

GOES-15 MVFR Probability and Suomi NPP VIIRS infrared Brightness Temperature Difference (BTD) products [click to enlarge]

GOES-15 MVFR Probability and Suomi NPP VIIRS infrared Brightness Temperature Difference (BTD) products [click to enlarge]

Daylight images of GOES-15 Visible (0.63 µm) data (below) showed the dissipation of the Tule fog during the 1600-2200 UTC (8 am – 2 pm local time) period. The brighter white snow pack in the higher elevations of the Sierra Nevada was also very evident in the upper right portion of the satellite scene.

GOES-15 Visible (0.63 µm) images [click to play animation]

GOES-15 Visible (0.63 µm) images [click to play animation]

One ingredient contributing to this Tule fog event was moist soil, from precipitation (as much as 150-200% of normal at some locations in the Central Valley) that had been received during the previous 14-day period (below).

Total liquid precipitation and Percent of normal precipitation for the 14-day period ending on 31 January 2017 [click to enlarge]

Total liquid precipitation and Percent of normal precipitation for the 14-day period ending on 31 January 2017 [click to enlarge]

Oil well fire in Utah

January 6th, 2017

GOES-15 Visible (0.63 µm) images, with hourly surface reports [click to play animation]

GOES-15 Visible (0.63 µm) images, with hourly surface reports [click to play animation]

GOES-15 (GOES-West) Visible (0.63 µm) images (above) showed a small, short-lived black cloud that formed south/southwest of Vernal (station identifier KVEL) in northeastern Utah on 06 January 2017. This feature was the result of a fire at an oil well site (media report | well location) that apparently started around 11:30 am local time (1830 UTC); the black cloud from the burning oil tanks — which was first apparent on the 1930 UTC visible image — stood out well against the snow-covered ground. The initial northwestward transport of the smoke plume was consistent with lower-tropospheric winds in Grand Junction, Colorado rawinsonde data at 07 January/00 UTC, which showed southeasterly winds as high as 784 hPa (2185 meters or 7169 feet above ground level). The sounding profile also showed that this height was the top of a well-defined temperature inversion, which acted as a cap to prevent the smoke from reaching higher altitudes (photo).

GOES-13 (GOES-East) Visible (0.63 µm) images (below) also displayed the dark smoke plume. The viewing angles from the 2 satellites were similar (~53 degrees from GOES-15 vs ~57 degrees from GOES-13), but the time sampling was slightly better from GOES-15 (due to the extra “SUB-CONUS” scan images at :11 and :41 minutes nearly every hour). Image frequency will be even better with the GOES-R series of satellites (beginning with GOES-16), with routine scans every 5 minutes; the visible image spatial resolution will also be improved (to 0.5 km, vs 1.0 km with the current GOES).

GOES-13 Visible (0.63 µm) images, with hourly surface reports [click to play animation]

GOES-13 Visible (0.63 µm) images, with hourly surface reports [click to play animation]

MODIS Visible (0.645 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images from a 2036 UTC overpass of the Aqua satellite (below) showed the black smoke cloud in the Visible, but there was no evidence of a fire “hot spot” in the Shortwave Infrared (the media report indicated that the fire was extinguished about 2 hours after it started, which would have been around or just before the time of the MODIS images). On the Infrared Window image, the smoke plume actually did exhibit a slightly colder (darker blue color enhancement) signature, which is unusual since conventional fire and wildfire smoke is normally transparent to thermal radiation.

Aqua MODIS Visible (0.645 µm) and Shortwave Infrared (3.7 µm) images at 2036 UTC [click to enlarge]

Aqua MODIS Visible (0.645 µm) and Shortwave Infrared (3.7 µm) images at 2036 UTC [click to enlarge]

A view of the 250-meter resolution Aqua MODIS true-color Red/Green/Blue (RGB) image from the MODIS Today site is shown below.

Aqua MODIS true-color image at 2036 UTC [click to enlarge]

Aqua MODIS true-color image at 2036 UTC [click to enlarge]