5-minute CONUS Sector GOES-18 (GOES-West) Visible images with an overlay of the Fire Mask derived product (above) showed the evolution of the Floriston Fire thermal signature (red pixels) as the vegetation fire grew near the California/Nevada border on 16 September 2026. Evacuation Orders were issued for areas near the fire — and Interstate 80 in the vicinity of Verdi, Nevada was closed to westbound traffic.

As the Floriston Fire smoke plume drifted northeastward across far western Nevada, it periodically reduced the surface visibility to 9 miles at Reno Stead Airport KRTS (below).

5-minute GOES-18 GeoColor RGB images with an overlay of Next Generation Fire System (NGFS) Fire Detection polygons (below) provided a closer view of the thermal signature, smoke plume and occasional bursts of pyrocumulus clouds produced by the Floriston Fire (the initial NGFS detection occurred at 1716 UTC). Wind gusts (red numbers in the lower right corner of the Surface Observation plots) in the vicinity of the fire were as high as 28 mph.

Even though the satellite viewing angle was larger for GOES-19 (GOES-East), that GeoColor RGB image + NGFS Fire Detection polygon perspective is shown below. Due to this larger viewing angle (64.44 degrees for GOES-19, vs. 48.95 degrees for GOES-18), the GOES-19 NGFS polygons appeared larger and somewhat distorted.

A toggle between 1846 UTC NGFS Fire Detection polygons from GOES-18 vs. GOES-19 projected onto a terrain map (below) highlighted the larger GOES-19 NGFS polygons. Note that the central red (hottest) NGFS polygon was centered along the eastern slopes of the Verdi Range (which has maximum elevations of 7000-8000 feet) — perhaps giving GOES-19 a somewhat more direct view of the Floriston Fire.

This terrain apparently played a role in the magnitude of NGFS parameters sensed by the 2 satellites at 1846 UTC (below) — in spite of the larger viewing angle of GOES-19, it detected a peak 3.9 µm infrared brightness temperature of 131ºC (vs. 110ºC from GOES-18) and a corresponding Pixel FRP (Fire Radiative Power) of 2921.11 MW (vs. 1005.91 MW from GOES-18).

During the subsequent nighttime hours, the bright glow of the Floriston Fire was evident in a NOAA-20 VIIRS Day/Night Band image at 1027 UTC (3:27 AM PDT) on 17 September (below).

View only this post Read Less

As an anomalously-deep low pressure system was moving eastward from the Chukchi Sea to the Beaufort Sea off the northern coast of Alaska (surface analyses), strong southwesterly to westerly surface winds caused inland flooding that led to some road closures in the Utqiagvik (formerly Barrow) area on 12-13 September 2026. 10-minute Full Disk scan GOES-18 (GOES-West) Water Vapor images centered on Barrow Post-Rogers Airport (above) showed the cloud features (brighter shades of white) associated with the low pressure system, and dryer air (darker shades of blue) behind its cold front — and included plots of hourly surface wind barbs and wind gusts.

A listing of Barrow Post-Rogers Airport (PABR) surface observations (below) showed that peak wind gusts were 50-51 knots for 3 consecutive hours (0553-0753 UTC on 13 September).

10-minute GOES-18 Infrared Window images (below) included plots of surface wind barbs and peak wind gusts. (The peak gust of 51 knots at PABR occurred at 0701 UTC)

A toggle between VIIRS Infrared Window images from Suomi-NPP and NOAA-21 (below) provided a more detailed view of the clouds associated with the offshore low pressure system.

A Public Service Announcement issued by Alaska’s North Slope Borough (below) detailed the flooding-related road closures in Utqiagvik.

View only this post Read Less

1-minute Mesoscale Domain Sector GOES-18 (GOES-West) Infrared Window images (above) showed Category 2 Hurricane Lowell as its center moved northeastward (track) and passed about 40 miles west of the Hawaiian island of Ni’ihau on 08 September 2026. While sparse, 1-minute GOES-18 GLM Flash Points did indicate that some intermittent lightning activity was present. A well-defined eye was no longer discernible in GOES-18 Infrared Window imagery during the time period shown.

Tendrils of transverse banding were very apparent within the southwestern and western quadrants of Lowell (below), embedded in the anticyclonic outflow at high altitudes. (Transverse banding is a satellite signature often associated with aircraft turbulence, as discussed in these blog posts.)

A closer view of 1-minute GOES-18 Infrared Window images (below) allowed for a better depiction of the peak wind gusts that occurred on the island of Kaua’i — which included 92 mph at RAWS site Puu Lua, and 73 knots (84 mph) at METAR sites Lihue (PHLI) and Kekaha (PHBK). A list of wind gusts across the other Hawaiian islands included 80 mph in Maui County and 75 mph in Honolulu County.

The coldest cloud-top infrared brightness temperature associated with one of Lowell’s convective bursts was -85.02 C at 0639 UTC (below).

According to a plot of rawinsonde data from Lihue at 0600 UTC on 08 September (below), the -85 C cloud-top infrared brightness temperature roughly corresponded to the the Most Unstable (MU) air parcel’s Maximum Parcel Level (MPL), located around 110 hPa or 16.3 km.

Also of note in the Lihue sounding shown above was the Precipitable Water (PW) value of 2.70 inches — which, according to a climatology of Lihue sounding PW (below) was a new record daily maximum PW for 08 September, and also may have been the highest PW on record for Lihue (eclipsing the previous record of 2.47 inches).

The MIMIC Total Precipitable Water product (below) showed that Lowell was drawing rich tropical moisture northward into its circulation from the Intertropical Convergence Zone, as the hurricane eventually turned northeastward (track) to pass over the far western part of the Hawaiian island chain.

A Metop-C AMSU Rain Rate derived product at 0804 UTC (below) did happen to show a ragged eye-like structure associated with Lowell at that time, just southwest of Ni’ihau. Rainfall across the Hawaiian Islands was as high as 21.11 inches at Kilohana on Kaua’i.

___________________________________________

As previously documented on this blog, Hurricane Lowell first reached Category 5 intensity on 02 September.

View only this post Read Less

JMA Himawari-9 Ash RGB images created using Geo2Grid (above) showed a major eruption of Anak Krakatau in Indonesia, which began around 1620 UTC on 04 September 2026. A middle-tropospheric volcanic ash cloud (depicted by shades of red to magenta) remained closer to the volcano — while an upper-tropospheric SO₂ cloud (shades of yellow-green) moved rapidly west-southwestward.

Large #eruption of #Krakatau #volcano (#Indonesia) started at ~16:30 UTC on Sept 4, and is continuing as of 13:00 UTC on Sept 5. #NOAA-20 OMPS satellite data showing injection of ~0.2 Tg SO? into the upper troposphere by 06:50 UTC on Sep 5.

— Prof. Simon Carn (@simoncarn.bsky.social) 2026-09-05T13:45:18.892Z

After sunrise on 05 September, Himawari-9 True Color RGB images (below) showed the middle-tropospheric volcanic ash cloud as shades of brown, with pulses of brighter white upper-tropospheric volcanic cloud (a mixture of water vapor, ash and SO₂) moving quickly westward away from the volcano. Ash eventually drifted northward over parts of the island of Sumatra, and eastward over parts of the island of Java.

A radiometrically-retrieved Ash Height product from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) indicated that ash from the eruption likely reached maximum altitudes in the 18-20 km range (black enhancement).

A plot of rawinsonde data from Jakarta International Airport, located east of Krakatau on the island of Java (below) showed lighter and variable-direction winds in the mid-troposphere (within the 650-450 hPa pressure layer, or altitudes of 3.7-7.0 km), with stronger easterly winds in the upper troposphere (especially within the 300-200 hPa pressure layer, or altitudes of 9.7-12.5 km).

===== 06 September Update =====

On 06 September, Himawari-9 True Color RGB images (above) showed the hazy signature of residual lower-altitude volcanic ash across the region — although the ash was not as thick as on the previous day, so it did not exhibit the same shades-of-brown signature. Nearly 3000 flights were suspended from Jakarta International Airport during its 2-day closure after the eruption of Krakatau.

A NOAA-21 VIIRS Day/Night Band image at 0533 UTC on 06 September (below) included a cursor sample of the Jakarta International Airport (identifier WIII) METAR observation, which included Volcanic Ash (VA).

A plot of surface observation data from Jakarta International Airport (below) indicated that Volcanic Ash was reported beginning at 1900 UTC on 05 September, with the volcanic ash restricting surface visibility to 4-7 miles.

View only this post Read Less