A total solar eclipse occurred across the southern Pacific Ocean and parts of South America on 02 July 2019 — GOES-17 (GOES-West) “stretched” True Color Red-Green-Blue (RGB) images (above) showed the eastward progression of the eclipse shadow.

On the view from GOES-16 (GOES-East), the eclipse shadow can be seen beginning to move across South America just before sunset (below). Grayscale GOES-16 Infrared imagery is displayed where there is not enough (or there is no) sunlight to use any of the ABI Visible and Near-Infrared spectral bands for RGB imagery.

Full Disk GOES-17 and GOES-16 True Color RGB imagery combined and displayed in a Mollweide projection is shown below (courtesy of Rick Kohrs, SSEC).

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the eye of Category 4 Hurricane Barbara on 02 July 2019. Mesovortices were briefly seen within the eye in the Visible imagery. Barbara was moving through an environment of low deep-layer wind shear and over warm water, factors favorable for rapid intensification (ADT | SATCON).

DMSP-17 SSMIS Microwave (85 GHz) imagery from the CIMSS Tropical Cyclones site (below) showed a closed eyewall at 1448 UTC.

A 1700 UTC  GOES-17 “Red” Visible image with an overlay of Metop-A ASCAT winds (below) revealed surface scatterometer wind speeds as high as 76 knots just north of the eye.

===== 03 July Update =====

Barbara maintained Category 4 intensity on 03 July — and 1-minute GOES-17 Visible and Infrared GOES-17 images (above) provided a better view of mesovortices within the eye.

View only this post Read Less

Back in late March 2019, the Cross-track Infrared Sounder (CrIS) suffered an anomaly such that the mid-wave portion of the electromagnetic spectrum (a part that includes channels sensitive to water vapor) was not scanned properly. Thus, NUCAPS soundings created from Suomi-NPP were lost (link). Today, NUCAPS soundings created using NOAA-20 (which has the same instruments as Suomi-NPP) began flowing into AWIPS. Data from shortly after 1500 UTC were the first to appear.

NUCAPS profiles from NOAA-20 are processed somewhat differently than those from Suomi-NPP as far as latency: NOAA-20 NUCAPS profiles show up more quickly — typically within an hour of the observations time — in AWIPS than NPP NUCAPS profiles did. This is important because the thermodynamic information in these mid-afternoon observations is important in judging destabilization relative to morning soundings.

When Suomi NPP was launched, two independent sets of electronics were present on CrIS; the ‘A’-side set of electronics were used until March; the ‘B’-side electronics have been used since June, and mid-wave observations from Suomi-NPP’s CrIS are now available at this site. However, NUCAPS soundings are not yet being created from Suomi-NPP because the A-side and B-side electronics have different statistical behavior that must be accounted for in the Regression used to start the NUCAPS processing.

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) images (above) showed the development of thunderstorms over the far southern end of the Alaska Panhandle on 27 June 2019. These storms intensified as they moved southeastward toward the Misty Fjords area of Alaska (located east and southeast of Ketchikan PAKT) — and when a significant lightning jump was noted with the strongest storm, NWS Juneau issued their first-ever Severe Thunderstorm Warning at 0249 UTC. A few thunderstorm overshooting tops could be seen in the visible images (for example, at 0230 UTC).

The Severe Thunderstorm Warning polygon is shown below.

GOES-17 “Clean” Infrared Window (10.35 µm) images (below) revealed minimum cloud-top infrared brightness temperatures around -60ºC (darker red enhancement).

A comparison of GOES-17 “Red” Visible (0.64 µm) images at 1-minute intervals with GOES-15 Visible (0.63 µm) images at 15-30-minute intervals (below) helps to underscore the importance of 1-minute imagery for identifying and tracking the pulse-type of thunderstorms that developed on this day. Also evident is the brighter appearance of the GOES-17 Visible imagery — the ABI instrument on the newer GOES-R Series benefits from on-orbit visible calibration, which mitigates the visible detector degradation that plagued the older GOES series.

Additional information about this severe thunderstorm event is available on a FDTD GOES Applications Webinar.

On a side note, a larger-scale view of GOES-17 Visible imagery (below) showed a curious thin elongated feature moving southwestward from Yukon across the Alaska Panhandle to the Gulf of Alaska, which became more obvious later in the day as the lower sun angle increased forward scattering. This feature was casting a shadow onto the marine boundary layer stratus clouds over the Gulf of Alaska (0250 UTC image).

This feature was also apparent in GOES-17 Near-Infrared “Cirrus” (1.38 µm) images (below), since that spectral band excels at the detection of atmospheric particles that are efficient scatterers of light (such as cirrus ice crystals, dust, smoke and volcanic ash/sulfate). In fact, this was a streamer of high-altitude sulfate from the Raikoke eruption on 21 June — and this thin volcanic filament could be unambiguously identified earlier in Cirrus imagery than in Visible imagery (for example, over Yukon at 1950 UTC, before forward scattering became large enough to aid identification at visible wavelengths).

View only this post Read Less