GOES-14 SRSO-R: pyrocumulus clouds over the Rey Fire in California

August 22nd, 2016

GOES-14 0.63 µm Visible (top), 3.9 µm Shortwave Infrared (middle) and 10.7 µm Infrared Window (bottom) images [click to play MP4 animation]

GOES-14 0.63 µm Visible (top), 3.9 µm Shortwave Infrared (middle) and 10.7 µm Infrared Window (bottom) images [click to play MP4 animation]

The GOES-14 satellite was in SRSO-R mode on 22 August 2016, providing images at 1-minute intervals over the western United States. A 3-panel comparison of Visible (0.63 µm), Shortwave Infrared (3.9 µm) and Infrared Window (10.7 µm) images (above; also available as a large 110 Mbyte animated GIF) showed that there were multiple bursts of pyrocumulus (pyroCu) clouds over the Rey Fire in southern California — while the bulk of the smoke was being transported westward over the offshore waters of the Pacific Ocean, smoke that was ejected to higher altitudes by the pyroCu clouds sent a plume of smoke drifting to the southeast.

The nearby Vandenberg rawinsonde data profile (below) suggests that the pyroCu clouds vertically lofted smoke to an altitude of at least 6.7 km (the 449 mb pressure level), where winds shifted to a northwesterly direction. However, since the pyroCu cloud-top IR brightness temperatures never even made it to -20º C (cyan color enhancement on the bottom panels), the smoke probably wasn’t much higher than the 6.7 km altitude (sounding data).

Vandenberg Air Force Base rawinsonde report [click to enlarge]

Vandenberg Air Force Base rawinsonde report [click to enlarge]

A comparison of Suomi NPP VIIRS true-color and false-color Red/Green/Blue (RGB) images displayed using RealEarth (below) showed the dense plume of smoke drifting westward away from the active fire area (brighter shades of pink on the false-color image), along with a pyroCu cloud over the fire and the early stage of the southeastward-moving smoke plume aloft.

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

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

GOES-14 SRSO-R: wildfire in Idaho

August 21st, 2016

GOES-14 0.63 µm Visible (top), 3.9 µm Shortwave Infrared (middle) and 10.7 µm Infrared Window (bottom) images, with surface reports plotted in yellow [click to play MP4

GOES-14 0.63 µm Visible (top), 3.9 µm Shortwave Infrared (middle) and 10.7 µm Infrared Window (bottom) images, with surface reports plotted in yellow [click to play MP4 animation]

The Pioneer Fire in central Idaho produced another pyroCumulonimbus (pyroCb) cloud on 21 August 2016 (the first was on 19 August). GOES-14 was in SRSO-R mode, and sampled the fire with 1-minute imagery (above; also available as a large 73 Mbyte animated GIF) — a large smoke plume was evident on 0.63 µm Visible images as it moved eastward; large fire hot spots (red pixels) were seen on 3.9 µm Shortwave Infrared images; on 10.7 µm Infrared Window images, the cloud-top IR brightness temperature cooled to -35º C (darker green enhancement) between 2249-2307 UTC as it moved over Stanley Ranger Station (KSNY), not quite reaching the -40º C threshold to be classified as a pyroCb.

However, a 1-km resolution NOAA-19 AVHRR 10.8 µm Infrared Window image (below; courtesy of René Servranckx) revealed a minimum cloud-top IR brightness temperature of -48.3º C (dark green color enhancement).

NOAA-19 AVHRR 0.64 µm visible (top left), 3.7 µm shortwave IR (top right), 10.8 µm IR window (bottom left) and false-color RGB composite image (bottom right) [click to enlarge]

NOAA-19 AVHRR 0.64 µm visible (top left), 3.7 µm shortwave IR (top right), 10.8 µm IR window (bottom left) and false-color RGB composite image (bottom right) [click to enlarge]

A larger-scale comparison of the NOAA-19 AVHRR visible, shortwave infrared and infrared window images is shown below.

NOAA-19 Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images [click to enlarge]

NOAA-19 Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images [click to enlarge]

===== 23 August Update =====

Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm) and 11.45-3.74 µm brightness temperature difference images [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm) and 11.45-3.74 µm brightness temperature difference images [click to enlarge]

The Pioneer Fire continued to be very active on 22 August (exceeding 100,000 acres in total burn coverage since its start on 18 July), sending a large amount of smoke northeastward (OMPS Aerosol Index). During the following overnight hours, cold air drainage and the development of a boundary layer temperature inversion acted to trap a good deal of smoke in the Payette River valley to the west/southwest of Stanley KSNT. The active fire hot spots (black to yellow to red pixels) were evident on nighttime (1032 UTC or 4:32 AM local time) images (above) of Suomi NPP VIIRS Shortwave Infrared (3.74 µm) data, while illumination from the Moon (in the Waning Gibbous phase, at 69% of Full) showed the ribbon of smoke trapped in the valley (note that this signal was not due to fog, since it did not show up in the VIIRS 11.45-3.74 µm brightness temperature difference or “fog/stratus product”).

During the subsequent daytime hours of 23 August, 1-minute GOES-14 Visible (0.63 µm) images (below; also available as a large 114 Mbyte animated GIF) showed the gradual ventilation of smoke from the Payette River valley as the temperature inversion eroded and mixing via winds increased.

GOES-14 Visible (0.63 um) images, with plots of hourly surface reports [click to play MP4 animation]

GOES-14 Visible (0.63 um) images, with plots of hourly surface reports [click to play MP4 animation]

Deep cyclone over Hudson Bay

August 11th, 2016

GOES-13 Water Vapor (6.5 µm) images, with hourly surface observations [click to play animation]

GOES-13 Water Vapor (6.5 µm) images, with hourly surface observations [click to play animation]

GOES-13 (GOES-East) Water Vapor (6.5 µm) images (above) showed the intensification of a strong cyclone over Hudson Bay, Canada during the 09 August – 10 August 2016 period; the cyclone deepened to a central pressure of 980 hPa (28.94″ of mercury) at 06 UTC on 10 August.

Daily composites of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images visualized using RealEarth (below) showed the storm on 08, 09 and 10 August.

Suomi NPP VIIRS true-color RGB images [click to enlarge]

Suomi NPP VIIRS true-color RGB images [click to enlarge]

River valley fog in Wisconsin, Minnesota and Iowa

July 26th, 2016

Suomi NPP VIIRS 11.45 µm - 3.74 µm Infrared brightness temperature difference ("fog product") at 0735 UTC [click to enlarge]

Suomi NPP VIIRS 11.45 µm – 3.74 µm Infrared brightness temperature difference (“fog product”) at 0735 UTC [click to enlarge]

A nighttime image (above) of the Suomi NPP VIIRS 11.45 µm – 3.74 µm Infrared brightness temperature difference (often referred to as the “fog/stratus product”) showed the development of narrow fingers of river valley fog in parts of southwestern Wisconsin, southeastern Minnesota and northeastern Iowa at 0735 UTC or 2:35 am local time on 26 July 2016. At that time the surface visibility was reduced to 1/4 mile at Boscobel, Wisconsin (station identifier KOVS).

During the subsequent daylight hours, GOES-13 Visible (0.63 µm) images (below) revealed the extent of the valley fog which had formed (the yellow symbols denote stations reporting fog). However, this fog quickly dissipated quickly with strong heating from the July sun.

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 Visible (0.63 µm) images [click to play animation]

This region frequently experiences such episodes of river valley fog, but they are most common during the Autumn months as nights grow longer and nighttime temperatures get colder. In this late July event, the primary ingredient favoring fog formation was high soil moisture due to recent heavy rainfall (below), much of which occurred on 24 July.

7-day precipitation, departure from normal, and percent of normal {click to enlarge]

7-day precipitation, departure from normal, and percent of normal {click to enlarge]