* GOES-17 imagery shown here are preliminary and non-operational *

A comparison of Visible images from GOES-15 (GOES-West), GOES-17 and GOES-16 (GOES-East)  on 14 July 2018 is shown above — in addition to thunderstorms over the high terrain of the Sierra Nevada, the development of a pyrocumulus cloud (with a small overshooting top) can be seen over the Ferguson Fire that had been burning for nearly a day near Yosemite National Park in central California.

Images from GOES-16/17 are at 5-minute intervals, while image intervals from the older GOES-15 satellite range from 5-30 minutes. The improved spatial resolution of the GOES-16/17 0.64 µm visible imagery (0.5 km at satellite sub-point, compared to 1.0 km for GOES-15) allowed finer details of the overshooting top to be seen — and the improved image-to-image navigation of the new GOES-16/17 satellites was also apparent (note the significant navigation errors in a few of the GOES-15 images).

A photo from the ground (below) showed a large pyrocumulus cloud towering over the top of the dense smoke.

 

#FergusonFire Photo by Al Golub about an hour ago, 530 pm. pic.twitter.com/hCH593pDlw

— Dave Toussaint (@engineco16) July 15, 2018

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GOES-17 imagery shown here are preliminary and non-operational

GOES-16 and GOES-17 visible imagery shows pseudo-stereoscopic imagery of developing convection on 13 July (over Georgia, click here for animated gif) and on 14 July (over North Dakota, including a cell that caused a tornado, below (animated gif), and Mexico, at bottom (animated gif)).

To view these images in three dimensions, cross your eyes until 3 images are present, and focus on the image in the middle.

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GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) depicted the remnants of Hurricane Beryl, which was situated off the East Coast of the US on 13 July 2018. Note the presence of 2 apparent low-level circulation centers — the primary circulation became better exposed as areas of deep convection moved more quickly to the east.

Overlays of low-level (produced using Visible Band 2) and upper-level (produced using Water Vapor Band 8) Derived Motion Winds (below) highlighted the primary low-level circulation, as well as the trough aloft whose axis was located just to the west.

Contours of Deep-Layer Wind Shear from the CIMSS Tropical Cyclones site (below) revealed that there was a large gradient in shear over the region at 19 UTC, with higher shear northwest of the system — this verified the subjective appearance of high shear in that particular area, where low-level and upper-level Derived Motion Winds were nearly orthogonal.

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GOES-15 (GOES-West) Visible (0.63 µm) and GOES-16 (GOES-East) “Red” Visible (0.64 µm) images — displayed in the native projection of each satellite, and centered on Las Vegas, Nevada — are shown above, depicting the development of deep convection across parts of the Desert Southwest on 12 July 2018. While the GOES-15 satellite was in Rapid Scan Operations mode (providing 2 extra images nearly every hour, at :11 and :41), a GOES-16 Mesoscale Sector was providing images at 1-minute intervals. Numerous flash flood watches, warnings and advisories were issued by NWS Las Vegas during the course of the day as some of the storms produced heavy rainfall (with as much as 0.75 inch at Cal Nev Ari and 0.61 inch at Needles, California KEED).

Note that the GOES-15 Visible images do not appear as bright as those from GOES-16 — prior to the GOES-R Series of satellites, the performance of visible detectors degraded over time, leading to imagery that appeared more dim as the Imager instrument aged. Visible detectors on the new ABI instrument benefit from on-orbit calibration to remedy this type of degradation.

The corresponding GOES-15 Infrared Window (10.7 µm) and GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed cloud-top infrared brightness temperatures around -70ºC (black enhancement) associated with some the stronger thunderstorms; this was the tropopause temperature at an altitude of 16.7 km / 48,300 feet on 00 UTC Las Vegas rawinsonde data. The improvement in spatial resolution from 4 km (at satellite sub-point) with GOES-15 to 2 km with GOES-16 is very apparent — even though the satellite viewing angle is about 10 degrees higher for GOES-16 than it is for GOES-15.

Higher spatial resolution Infrared Window images from Terra/Aqua MODIS and Suomi NPP VIIRS (below) revealed a cloud-top infrared brightness temperature as cold as -79ºC in far northwestern Arizona on the 2017 UTC VIIRS image.

In addition to heavy rainfall, some thunderstorm winds created areas of blowing sand:

Ridiculous #Sandstorm in Death Valley National Park near the Mesquite Flats sand dunes. So much sand accumulating on the car that we had to turn on the wipers! Def one of the strangest weather experiences to date… #CAwx @NWSVegas pic.twitter.com/9zgj4Z2ksh

— Michael Charnick (@charnick_wx) July 13, 2018

The GOES-16 Total Precipitable Water derived product (below) showed that rich moisture was present across the Desert Southwest, fueling the development of the widespread convection. TPW values in the 1.0 to 2.0 inch range were seen over southeastern California, southwestern Arizona and far southern Nevada.

A 4-km resolution Terra/Aqua MODIS Total Precipitable Water product (below) indicated values in the 40-55 mm or 1.6-2.2 inch range.

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