10-minute Full Disk sector GOES-18 (GOES-West) Day Land Cloud Fire RGB, Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and “Red” Visible (0.64 µm) + Fire Power derived product (a component of the GOES Fire Detection and Characterization Algorithm FDCA) images (above) showed signatures of multiple wildfires across northeastern British Columbia (BC) and northwestern Alberta (AB), some of which produced numerous  pyrocumulonimbus (pyroCb) clouds late in the day on 22 September 2023. Several of these fires burned very hot, exhibiting 3.9 µm shortwave infrared brightness temperatures of 137.88ºC (the saturation temperature of GOES-18 ABI Band 7 detectors) — and for the large wildfire near Rainbow Lake AB (CWSH), Fire Power values intermittently reached the 6400-6405 MW range (which are the highest GOES Fire Power values sampled by this author for any wildfire).

True Color RGB images from the CSPP GeoSphere site (below) displayed the BC/AB pyroCb development, as well as widespread dense smoke from the many wildfires across the region.

A longer animation of GOES-18 Infrared images covering a larger area (below) showed that while two of the largest BC fires produced 1 to 4 pyroCb clouds each — pyroCb clouds are defined as having cloud-top 10.3 µm infrared brightness temperatures of -40ºC and colder, shades of blue — one of the two largest AB fires produced an amazing string of 7 pyroCb clouds (between 2300 UTC on 22 September and 0800 UTC on 23 September). About 100 miles downstream (northeast) of that prolific pyroCb-producing AB wildfire, smoke reduced the surface visibility to 1/2 mile for several hours at Hay River (CYHY) in the Northwest Territories.

The coldest cloud-top 10.3 µm infrared brightness temperature exhibited by the largest of the AB pyroCbs was -60.6ºC — placing it at an altitude near 12 km (just below the tropopause) as seen in a plot of rawinsonde data from Fort Nelson BC (CYYE) (below).

On the following day, the leading edge of high-altitude BC/AB pyroCB smoke plumes could be seen moving southeastward across Hudson Bay in True Color RGB images from both GOES-18/GOES-West (above) and GOES-16/GOES-East (below).

View only this post Read Less

The National Weather Service forecast office on Guam (at 13.4^oN, 144.7^oW) is paired with an L/X band satellite receiver that can download data from Polar Orbiting satellites, which data can subsequently be processed by Polar2Grid software to produce useful products. The animation above shows 4 different Himawari-9 Band 13 images on 21 September, a day when Guam was experiencing intermittent rains as a feature moved northward. When do you think the rain was heaviest? Did you choose 1130 UTC? That is what the microwave-derived rainrate suggests (see below). A side-by-side comparison of the Himawari Band 13 imagery and Microwave-derived rain rate is here. A meteorogram for Guam International airport is here: Heaviest observed rains were around 1200 UTC; rains ended around 1500 UTC. That is in agreement with the microwave diagnoses.

---

What was the environment around Guam? Microwave estimates of Total Precipitable Water, below, (source), show Guam near the northern edge of a moisture-rich band of tropical origins. Advanced Scatterometer winds, at bottom, from MetopB and MetopC (times as noted in the caption), show a convergence line nearing Guam on 20 September (on 21 September, ASCAT did not sample over Guam).

---

Thanks to Douglas Schumacher, CIMSS, for supplying the imagery from the Guam Direct Broadcast antenna!

View only this post Read Less

CSPP Geosphere, often featured on this blog, is a website which allows users to view near-real-time imagery of GOES-East and GOES-West ABI data. All sixteen spectral bands on the ABI are available to view, along with RGB imagery. Full disk products are available, along with Continental United States (CONUS) and the two mesoscale sectors. Every ten-minute Full disk frame of data is included on CSPP Geosphere. The data is archived back approximately two weeks, allowing users to look at past events. The interface of the CSPP site allows the user to select specific time frames they are interested in viewing. CSPP allows users to save animations with 144 or fewer frames, making the frame selection tool very useful.

To create an animation like the one below, the user can select a frame every third hour, going back seven days. This creates a weekly animation, showing frames every three hours (0000Z, 0300Z, 0600Z, 0900Z, etc.) for each day.

The video shows a fairly active week for cyclones in the Atlantic. Hurricane Lee made landfall on 2023-09-16 as a post-tropical cyclone on the western coast of Nova Scotia. There is also Hurricane Margot, which has veered to the east to the mid-Atlantic, far away from any coastline.

On 2023-09-17, the structure which will become Hurricane Nigel becomes quite apparent. It is designated a hurricane on 2023-09-18 at 0900Z. By 2023-09-19 at 0300Z, the rotational structure is clear and an eye is apparent. On 2023-09-20 around 1200Z, Nigel’s path begins to move eastward. It is forecast to devolve into an extratropical cyclone and currently poses no threat to human populations.

The full disk animation from CSPP Geosphere allows users to view many interesting weather phenomena over the Atlantic Ocean. Along with the lifecycles of hurricanes, one can see large amounts of dust blowing off of the Sahara Desert in West Africa. At the mouth of the Amazon River, there is visible river sediment outflow from the Amazon’s delta and estuary.

View only this post Read Less

GOES-West imagery, above, from the CSPP Geosphere site, shows Hawaii in a tradewind regime (direct link to animation). The animation, from 0121 to 0556 UTC on 21 September 2023, shows the steady progression of cloud lines moving east-to-west, with embedded regions of apparent showers that generate outflow boundaries. At 0431 UTC, Sentinel-1A overflew the eastern Hawai’ian islands, and a high-resolution picture of the surface winds resulted (Data are available online as well: Normalized Radar Cross Section Data, and Winds). The three wind footprints are stitched together below.

Strong winds — nearly 30 knots — are associated with a modest looking (and decaying) convective cell just to the east of Maui. None of the convection in this scene reaches particularly high into the atmosphere; cloud top brightness temperatures are in the 5-10^o C range. The Hilo Sounding at 0000 UTC on 21 September 2023 shows a tradewind inversion top at 750 hPa, suggesting the clouds reached to about that level. (The strong winds of the Alenuihaha channel are also shown!) Note also the strong winds in the lee of the Big Island of Hawai’i.

---

Sentinel orbits are such that exact repeats occur every 12 days. The Ocean Virtual Laboratory allows a user to track the overpasses.

View only this post Read Less