GOES-18 Visible imagery, above, from the CSPP Geosphere site, shows Gilma and Tropical Invest #91E (the invest became a tropical depression at 1500 UTC on 22 August; see below) at around 17^oN latitude on 21 August 2024 in the tropical eastern Pacific. The animation below shows the same scene on 20 August, and the organizational improvement in the invest is apparent. On the 20th, the low level circulations were separate from the convection. On the 21st, above, the low-level circulations are underneath the convection. Slow organization has occurred.

By sunrise on the 22nd, below (link), Gilma is a hurricane, with an invest to its east; Invest 91E has moved west of 140^oE, become the responsibility of the Central Pacific Hurricane Center in Honolulu, and organized enough to become a tropical depression.

The invest was sampled from the direct broadcast site at Honolulu (data here). The toggle below compares Suomi-NPP I05 VIIRS imagery (11.45 µm) and the Suomi-NPP ATMS Rain Rate shortly after 1100 UTC on 22 August. The system is in a region of warm SSTs and low shear. Interests in Hawaii should continue to monitor its evolution.

For more information on this system, refer to the Central Pacific Hurricane Center and the National Weather Service office in Honolulu. CPHC has started issuing advisories on this system (tropical Depression 1C) as of 1500 UTC on 22 August.

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The moon was visible in Japan Meteorological Agency (JMA)‘s AHI (-9) imagery on 21 August 2024.

A similar mp4 animation as above, but a quicker animation speed.

Himawari-9 imaged more than just clouds over the southern Pacific Ocean when the recently full moon peeked out from behind Earth. pic.twitter.com/eXPKt4rN2I

— CIRA (@CIRA_CSU) August 22, 2024

GOES

While the GOES-R ABI series also scans the moon when it is near the Earth, only the remapped (to the Earth) pixels are distributed as part of the rebroadcast data. Special processing from Level 0 data is needed to see the off Earth edge pixels with ABI. GOES-1 through GOES-15 imagers did allow to sometimes see the moon off the Earth. Examples from GOES-8, GOES-12, and GOES-13.

H/T

Thanks to JMA for the AHI data (via NESDIS/STAR) and the UW/SSEC Data Services. McIDAS-X was used for these image combinations. T. Schmit works for NOAA/NESDIS/STAR and is stationed in Madison, WI.

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GOES-18 True-Color imagery, above, from the CSPP Geosphere website (link to animation above), shows convection moving over northeastern Wyoming, leaving in its wake a series of smoke plumes: wildfires caused by lightning. The screenshots below were captured from the Real Earth instance of NGFS imagery (link), and they show LightningCast probability and Flash Extent Density as well as NGFS Fire Detections.

The image below, for 1550 UTC, includes large LightningCast probabilities (and observed Flash Extent Density) from GOES-East. These features are moving northeastward through Wyoming as shown in the animation above.

At 1655 UTC, below, the convection has moved into extreme northeast Wyoming. NGFS fire pixels are shown in the wake of the departing convection: dry thunderstorms appear to have initiated a fire (this is the House Draw fire). Lightning Probabilities continue to be enhanced with the convection.

Convection continues later in the day on the 21st, as shown in the series of images below: 1935 UTC and 2225 UTC on 21 August, and 0000 and 0400 UTC on 22 August. By 0400 UTC on 22 August, most of the convection has moved northeast of Wyoming, leaving behind a series of wildfires as indicated by the NGFS detections. The largest of these was the House Draw fire. Notice how quickly the area consumed by the House Draw fire is expanding.

This example of convection-induced fires shows why LightningCast probabilities are included in the NGFS RealEarth displays!

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This fire was also discussed on the Satellite Liaison Blog here. Note that this fire also included a Fire Weather Warning issuance from WFO Riverton in collaboration with local Emergency Managers.

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Himawari-9 airmass RGB imagery, above, shows the extratropical transition of Typhoon Ampil. At the beginning of the animation, the typhoon is approaching Japan from the south. By 0000 UTC on 17 August, the typhoon has moved east of Japan, and a Potential Vorticity anomaly just west of the storm (identifiable by the orange hue in the RGB) suggests the storm is starting to become extratropical. By 0000 UTC on 19 August, a second mid-tropospheric potential vorticity anomaly (also identifiable by its orange hue in the RGB), is moving over Kamchatka and the Kuril Islands just west of the evolving typhoon and being incorporated into the storm. Airmass RGBs are a useful product in highlighting the possibility of a rapid transition of typhoons to a strong extratropical storm (another example is 2022’s Typhoon Merbok).

Merbok was a very intense storm after it became extratropical, far stronger and damaging than Ampil. One notable difference between the two storms was the connection between the storms and tropical moisture. MIMIC Total Precipitable Water fields for Merbok, below, at 1200 UTC on 14-15 September 2022 (source), show a connection to the rich moisture of the Intertropical Convergence Zone (a MIMIC TPW animation is also available here, from this blog post). That direct connection is missing for Ampil, and might be one of many reasons for the differences in extratropical storm strength.

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Thanks to Eddie Zingone, WFO ANC for mentioning Ampil’s extratropical transition on a telecon this week!

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