GOES-West true color imagery, above, from the CSPP Geosphere site (link), shows Hurricane Barbara northeast of Tropical Storm Cosme in the eastern Pacific. Active convection is apparent over both storm centers during the course of the day. What does the future hold for these storms? MIMIC Total Precipitable Water (source), below, shows the storms within a band of rich moisture, but forecasts paths for both are towards the north and drier air.

The predicted path of the storms is over much colder water. Do not expect to hear much about these storms by the end of the week!

Both storms are within a band of relatively low shear as shown below. It is increasingly cool SSTs along the storm paths, and an increasingly dry atmosphere, that will be controlling the intensity of these storms in the near future.

HYSAT and OCEANSAT scatterometers both sampled both storms on 9 June, as shown in the toggle below. HYSAT overflew the storms at 1358 UTC and OCEANSAT overflew at 2014 UTC. Both show the cyclonic circulation centers. Barbara’s center is moving northwest whereas Cosme’s is moving west-northwest.

For more information on these storms, refer to the National Hurricane Center. In addition, the SSEC/CIMSS Tropical Weather site has dedicated pages for both Barbara and Cosme.

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1-minute Mesoscale Domain Sector GOES-19 (GOES-East) “Red” Visible (0.64 µm) images (above) showed supercell thunderstorms that produced tornadoes, hail as large as 4.25″ in diameter and wind gusts as high as 100 mph (SPC Storm Reports) across parts of Texas and Oklahoma on 08 June 2025. Frequent pulses of overshooting tops were apparent with these thunderstorms.

In the corresponding 1-minute GOES-19 “Clean” Infrared Window (10.3 µm) images (below), the coldest cloud-top infrared brightness temperatures associated with some of the pulsing overshooting tops were -80ºC or colder (shades of magenta embedded within bright white regions).

Many of these thunderstorms were moving into a broad corridor of enhanced instability and moisture that was in place from northern Texas into southern Oklahoma, as shown by GOES-19 CAPE (above) and Total Precipitable Water (below) derived products.

1-minute GOES-19 Visible images with an overlay of GLM Flash Points (below) displayed abundant lightning activity with these thunderstorms.

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GOES-18 imagery from the CSPP Geosphere site, above, shows a thin line of trade wind cumulus from which strong convection develops over Tutuila (the main island of American Samoa). The heavy rains prompted the issuance of Flood Advisories. What products or imagery might have helped in anticipating this convective development?

LightningCast probabilities between 0000 and 0100 UTC on 8 June, below, computed using this CSPP Geo software, show small probabilities developing by 0100 UTC. A forecaster viewing these fields might see them and conclude that something bigger is about to commence.

The Clean Window infrared imagery below, from 0040 – 0110 UTC on 8 June 2025, shows the development of the convection at the western tip of Tutuila. Cooler brightness temperatures are apparent at 0050 UTC — that an the increase in LightningCast probability (shown above) might be enough to convince a forecaster that convection is starting.

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GOES-18 Lifted Index fields, a field that is computed in clear skies only, shows an atmosphere slowly destabilizing around Tutuila from 2300 on the 7th to 0210 on the 8th, changing from about -1.1 to -1.7. So — the cumulus line is approaching an area that is becoming less stable. Strong convection has developed by 0200 UTC.

It’s worth mentioning that parallax errors from GOES-18, overhead at 137.2^oW (compared to 171^oW for Pago Pago) means that the convection that is mapped to the west of Tutuila is, in reality, over the island. Parallax computations (link) suggest that a 30000-foot storm top would be displaced by almost 9 km, or about 4 pixels. The convection was also developing in a region with a bit more moisture (as diagnosed by GOES-R Total Precipitable Water, TPW, below). Regions just east of Tutuila become more moist over the course of the animation below; TPW increases from about 1.8″ to 2″

The Pago Pago sounding from 0000 UTC on 8 June 2025, below, shows abundant instability available if a modest capping inversion can be broken.

Thanks to WSO Pago Pago for alerting me to this challenging case. The interpretation of the Lifted Index is very much simpler because the colorbar bounds were changed! Change defaults to highlight subtle features.

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Given that the narrow lines of tradewind cumulus are possible regions of convective development, what tools are available to monitor them at night? The Day Night Band on NOAA-20/NOAA-21/Suomi-NPP produces visible imagery at night. The image below, from the NASA Worldview site, shows a narrow line of tradewind cumulus approaching the Samoan Islands and the convection from earlier moving north of the islands. June 8th was two days before a full Moon, so there was ample illumination.

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Today at 17:40 UTC, NOAA decommissioned one of its three remaining legacy polar-orbiting weather satellites, NOAA-18. The spacecraft was launched on May 20th, 2005, and was declared operational on August 30th, 2005. For nearly 20 years, NOAA-18 collected weather information across the whole globe, with every point on Earth in view, at minimum, every 12 hours.

The final NOAA-18 orbit collecting data over the continental United States occurred around 16:08 UTC today. At this point, the AVHRR visible/IR imaging sensor was no longer collecting infrared bands 4 and 5. The HRPT direct broadcast signal during this overpass was collected by SSEC’s X/L-band tracking antenna in Madison, and processed using EUMETSAT’s AAPP and CSPP Polar2Grid software:

Band 1: “Red Visible” [0.63 µm]	Band 2: “Vegetation Near-IR” [0.86 µm]	Band 3A: “Snow/Ice Near-IR” [1.61 µm]

Of NOAA’s 5th generation POES spacecraft, 2 remain active: NOAA-15 and NOAA-19. Both are expected to be decommissioned later this summer. Prior to today, the last NOAA polar weather satellite to be decommissioned was NOAA-16 on June 9th, 2014. The JPSS constellation (S-NPP, NOAA-20, and NOAA-21) remains active as NOAA’s primary polar-orbiting weather satellites.

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