GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images (above) showed Hurricane Lorenzo as it rapidly intensified from a Category 2 storm at 00 UTC to a Category 4 storm by 15 UTC (ADT | SATCON) on 26 September 2019.

A toggle between VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 as viewed using RealEarth (below) provided a detailed view of the eye and eyewall region of Lorenzo at 1542 UTC and 1632 UTC. On the Suomi NPP Infrared image, note the transverse banding northwest of the eye, and a small packet of gravity waves southwest of the eye.

A DMSP-18 SSMIS Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) revealed a well-defined eyewall wrapping around the southern, eastern and northern periphery of the eye.

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1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images (above) showed the development of severe thunderstorms across parts of the Upper Midwest on 24 September 2019 — these storms produced hail as large as 2.5 inches in diameter in Nebraska, a wind gust to 80 mph in Minnesota and an EF3-rated tornado in Wisconsin (SPC Storm Reports | NWS Twin Cities | NWS La Crosse).

The corresponding 1-minute GOES-16 “Red” Visible (0.64 µm) images leading up to sunset are shown below.

A “probability of intense convection” model was run for this particular event (below).

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NOAA-20 has viewed the launch from Tanegashima Island of a Japanese Spacecraft (NASA Blog Coverage; YouTube video, launch is at minute 35 in the video). Brandon Aydlett, NWS Guam, noted the appearance of a very bright spot in the Day Night Band imagery from NOAA-20 at 1602 UTC on 24 September (and a hot spot as well in the infrared imagery shown below). (NOAA-20 and Suomi-NPP data in this blog post were downloaded at the Direct Broadcast Antenna at the Forecast Office in Guam). NOAA-20 Orbital passes (from this site) show an overpass near the island at 1605 UTC; Suomi NPP had a more direct overpass over the island around 1657 UTC. Compare the NOAA-20 image, above, timestamped 1602 UTC, to the Suomi NPP image, below, timestamped at 1654 UTC. The bright signal over Tanegashima at 1602 UTC is missing from the 1654 UTC Suomi NPP imagery.

Infrared Imagery captured the thermal signature of this launch as well. The hot spots in VIIRS imagery are obvious at 1602 UTC from NOAA-20, but not at 1654 UTC from Suomi NPP, at both 3.74 and 11.45, as shown below.

 

Himawari-8 shortwave infrared imagery also captured the launch, with a hot spot in a Japan Sector image at 1605 UTC on 24 September 2019, below.

There is a considerable parallax shift in the NOAA-20 imagery, as the VIIRS instrument is scanning at the limb in the image, and the rocket at the time was very high in the atmosphere. The parallax shift in the Himawari-8 imagery is less noticeable.

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1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the development of severe thunderstorms over southern/central Arizona from 1600-1900 UTC on 23 September 2019. The far western storm exhibited a well-defined Above-Anvil Cirrus Plume (AACP) that extended northeastward from the cold overshooting top (whose coldest infrared brightness temperature was -74ºC); note that the AACP feature appeared colder (shades of yellow to orange) on the Infrared images (for example, at 1817 UTC).

As the western storm began to weaken somewhat, a new storm just to the east (located about 20-30 miles north-northeast of the Phoenix metro area) began to intensify, prompting the issuance of a Tornado Warning at 1914 UTC (the last tornado warning issued by NWS Phoenix was 21 January 2010) — a brief EF0 tornado was documented (NWS Phoenix summary).

Tornado Warning including Cave Creek AZ, Carefree AZ, Camp Creek AZ until 12:45 PM MST pic.twitter.com/M5BDw2fuIE

— NWS Phoenix (@NWSPhoenix) September 23, 2019

Much of the moisture helping to fuel the development of this severe convection was from the remnants of Tropical Storm Lorena in the East Pacific Ocean — the northward transport of this moisture could be seen using the hourly MIMIC Total Precipitable Water product (below).

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Stability parameters from GOES-16 showed that the reigon of thunderstorm development was just east of a strong gradient in Convective Available Potential Energy.  The animation above shows the GOES-17 Clean Window;  in regions of clear sky, the baseline Derived Stability Index CAPE is shown.  CAPE values are zero over much of California (except for the southeasternmost corner) but they increase rapidly over Arizona to values approaching 1000 J/kg.

On 23 September, skies were clear enough that an instability signal was obvious in the clear-sky baseline CAPE. An ‘All-Sky’ product has been developed that can be used on days with more widespread cloudiness; it is available at this link. Values of All-Sky CAPE at 1156 and 1556 UTC on 23 September are shown below, and they also show a sharp gradient in the instability, and the link down to moisture from Lorena’s remants.

NOAA/CIMSS ProbSevere is a product designed to indicate the likelihood that a given object will produce severe weather within the next 60 minutes. An animation of the product at 5-minute intervals, below, shows that the right-moving radar cell (also associated, as noted above, with an AACP) that developed over far southwestern Arizona (becoming a warned storm at 1647 UTC) was very likely to produce severe weather.

Parameters that are used to determine the probability can be revealed at the ProbSevere site by mousing over the colored object contours.  The values for the warned storm over SW Arizona are shown below at 1650 UTC, 3 minutes after the warning was issued.  This image shows the 1710 UTC readout with the highest ProbWind value (76%); this image shows the 1725 UTC readout with the highest ‘ProbHail’ value (99%); ProbTor values on this day were not exceptionally large — for the later tornado-warned storm farther east, they were 28% at 1915 UTC and 30% at 1920 UTC.

CIMSS is developing a machine-learning tool that combines ABI and GLM imagery (that is, only satellite data) to identify regions where supercellular thunderstorms capable of producing severe weather might be occurring. An mp4 animation for this event (courtesy John Cintineo, CIMSS) is shown below.  (This experimental product was also shown in this blog post)

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