Hurricane Ian makes landfall in Florida

September 29th, 2022 |

GOES-16 “Clean” Infrared Window (10.3 µm) and “Red” Visible (0.64 µm) images [click to play animated GIF | MP4]

Overlapping 1-minute Mesoscale Domain Sectors provided 30-second interval GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) and “Red” Visible (0.64 µm) images (above) during a 7-hour period that included the landfall of Hurricane Ian along the southwest coast of Florida at 1905 UTC (Visible | Infrared) on 28 September 2022. Moving across very warm water (where buoy Sea Surface Temperature values were 82-85ºF), Ian intensified to a Category 4 hurricane at 1200 UTC, and further intensified as it neared the Florida coast to just below Category 5 strength (rated at 135 knot sustained winds). As Ian moved inland, peak wind gusts were as high as 140 mph, and heavy rainfall exceeded 10 inches within a 4-hour period (WPC Storm Summary). These strong winds quickly resulted in power outages to 96-99% of customers in DeSoto, Charlotte and Lee Counties by 2244 UTC — note the disappearance of surface plot data in the GOES-16 imagery after 20 UTC at sites such as Venice (peak gust 90 knots / 104 mph), Punta Gorda (peak gust 117 knots / 135mph) and Fort Meyers (peak gust 87 knots / 100 mph).

30-second GOES-16 Visible images with time-matched plots of GLM Flashes (below) indicated that lightning activity within the eyewall decreased as the eye of Ian approached the coast.

GOES-16 “Red” Visible (0.64 µm) images, with plots of GLM Flashes [click to play animated GIF | MP4]

In a comparison of ~500-meter resolution GOES-16 Visible and ~15-meter resolution Landsat-8 Panchromatc images valid at 1557 UTC — viewed using RealEarth (below) — the Landsat image provided a more detailed view of the cloud structures within the eye of Hurricane Ian as it was just off the west coast of Florida.

GOES-16 “Red” Visible (0.64 µm) and Landsat-8 Panchromatic (0.59 µm) images, valid at 1557 UTC [click to enlarge]

Ex-typhoon Merbok enters the Bering Sea

September 16th, 2022 |

GOES-17 Air Mass RGB images, with hourly plots of surface reports [click to play animated GIF | MP4]

GOES-17 (GOES-West) Air Mass RGB images with hourly plots of surface reports (above) showed the remnants of ex-Typhoon Merbok (storm track) moving northward across the Bering Sea (surface analyses) on 16 September 2022. This strong extratropical cyclone had an anomalously-low surface pressure as it moved northward — in fact, its central Mean Sea Level Pressure set a record for the month of September in the Bering Sea:

The storm center passed just northwest of Buoy 46035, where the peak wind gust was 68 knots (78 mph) at 1800 UTC and 1900 UTC on 16 September. These strong winds caused wave heights to 52 feet, which resulted in a notable upwelling of cooler water. Such strong southwesterly surface winds in the vicinity of Buoy 46035 occurred beneath a swath of anomalously-strong 925 hPa winds within the southeast quadrant of the storm. Two particularly adverse impacts of these strong winds were coastal erosion and flooding across much of western Alaska (more of the storm’s impacts are discussed here).

In the Air Mass RGB images, deeper shades of red-to-orange in the vicinity of the storm center vhighlighted areas where there was enhanced ozone within the atmospheric column (due to an anomalously-low tropopause ) — overlays of AK-NAM40 model Potential Vorticity (PV) 1.5 pressure (below) indicated that the “dynamic tropopause” near the storm center may have descended as low as the 900 Pa pressure level.

GOES-17 Air Mass RGB images, with overlays of AK-NAM40 model PV1.5 pressure [click to play animated GIF | MP4]

In a larger-scale view of GOES-17 Air Mass RGB images created using Geo2Grid (below), one interesting feature was a distinct plume of moist tropical air (highlighted by darker shades of green) that moved northward across the Aleutian Islands into the Bering Sea (for example, at 0600 UTC on 16 September in the warm sector of the storm).

GOES-17 Air Mass RGB images [click to play animated GIF | MP4]

The MIMIC Total Precipitable Water product (below) showed the north-northeastward transport of tropical moisture as Typhoon Merbok transitioned to an extratropical storm.

MIMIC Total Precipitable Water product [click to play animated GIF | MP4]

Additional information pertaining to this event is available here

Unusually low ice concentration in the Beaufort Sea and Chukchi Sea

September 13th, 2022 |

Suomi-NPP VIIRS Visible images [click to play animated GIF | MP4]

A sequence of Suomi-NPP VIIRS Visible images (above) showed a large area of ice-free water in the western Beaufort Sea and eastern Chukchi Sea north of Alaska — with limited sea ice concentration as far north as 80º N latitude — on 13 September 2022.  

False Color RGB images from NOAA-20 and Suomi-NPP, viewed using RealEarth (below) provided another depiction of the large ice-free region the Beaufort Sea (as well as adjacent portions of the Chukchi Sea).

False Color RGB images from NOAA-20 and Suomi-NPP [click to play animated GIF]

 Sea Ice Concentration (based on the NOAA Enterprise Algorithm) at 0000 UTC on 13 September (below) also showed limited ice coverage and concentration extending past 80º N latitude.

Sea Ice Concentration at 0000 UTC on 13 September [click to enlarge]

According to Rick Thoman (University of Alaska, Fairbanks), Beaufort Sea ice extent was the 9th lowest on record for this date:

Pyrocumulonimbus clouds in Oregon, Idaho and California

September 10th, 2022 |

An extended period of hot temperatures across much of the western US — where drought conditions were widespread — helped set the stage for large wildfires which produced several pyrocumulonimbus (pyroCb) clouds in parts of Oregon, Idaho and California during the 07-10 September 2022 period.

===== 07 September =====

GOES-18 Day Land Cloud Fire RGB images [click to play animated GIF | MP4]

GOES-18 (GOES-West) Day Land Cloud Fire RGB images (above) displayed numerous wildfires (clusters of red pixels) from far eastern Oregon into Idaho on 07 September 2022. Three of the larger fires — one in Oregon and two in Idaho — produced one or more pulses of pyroCb clouds during the day.

1-minute GOES-18 True Color RGB images visualized using CSPP GeoSphere (below) showed the smoke-laden cloud tops (shades of tan) associated with some of the pyroCb pulses from the eastern Oregon and central Idaho wildfires.

GOES-18 True Color RGB images [click to play MP4 animation]

4-panel displays of 1-minute Mesoscale Domain Sector GOES-18 Day Land Cloud Fire RGB, Shortwave Infrared (3.9µm), “Clean” Infrared Window (10.35 µm) and Cloud Top Temperature (below) provided a closer view of a vigorous pyroCb produced by the Moose Fire in far eastern Idaho (near the Montana border). During that time period, the maximum surface 3.9 µm infrared brightness temperature of the fire signature reached 137.88oC (the saturation temperature of GOES-18 ABI Band 7 detectors). The coldest pyroCb cloud-top 10.35 µm infrared brightness temperatures were -52oC, while the coldest Cloud Top Temperature derived product values were around -56oC.

GOES-18 Day Land Cloud Fire RGB (top left), Shortwave Infrared (3.9 µm, top right), Infrared Window (10.35 µm, bottom left) and Cloud Top Temperature (bottom right) [click to play animated GIF | MP4]

===== 08 September =====

GOES-17 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, middle) and “Clean” Infrared Window (10.35 µm, bottom) [click to play animated GIF | MP4]

1-minute GOES-17 (which resumed duty as GOES-West as of 1601 UTC on 08 September) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed a “marginal” pyroCb produced by the Mosquito Fire in California on 08 September 2022, whose coldest cloud-top 10.35 µm infrared brightness temperature reached -39oC (just shy of the -40oC threshold of pyroCb classification) — however, the Cloud Top Temperature derived product (not shown) did reach -42oC.

1-minute GOES-17 True Color RGB images (below) displayed the smoke-laden (shades of tan) cloud top of this “marginal pyroCb”.

GOES-17 True Color RGB images [click to play MP4 animation]

===== 10 September =====

As discussed in this blog post, the Cedar Creek Fire in Oregon had been producing a large smoke plume during the day on 09 September — and this trend continued into the overnight hours, as shown by a Suomi-NPP VIIRS Day/Night Band (0.7 µm) image valid at 1020 UTC on 10 September (below). Ample illumination by a Full Moon provided an excellent example of the “visible image at night” capability of the Day/Night Band (DNB).

Suomi-NPP VIIRS Day/Night Band (0.7 µm) image, valid at 1020 UTC on 10 September [click to enlarge]

In a closer view of of the Cedar Creek Fire, a toggle between the corresponding Suomi-NPP VIIRS DNB and Shortwave Infrared images (below) displayed the bright nighttime glow of the more active individual fires (as well as the dense smoke plume drifting northwestward) in the DNB image — and the thermal signature of fires along the northwestern perimeter was evident in the Shortwave Infrared image, even though the dense smoke plume was overhead.

Suomi-NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (11.45 µm) images, valid at 1020 UTC on 10 September [click to enlarge]

During the subsequent daytime hours, a sequence of 1-minute GOES-17 Day Land Cloud Fire RGB, Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Cloud Top Temperature product (below) showed that the Cedar Creek Fire produced a pyroCb cloud late in the day on 10 September 2022. During that particular time period, the maximum surface 3.9 µm infrared brightness temperature of the fire signature reached 138.71oC (the saturation temperature of GOES-17 ABI Band 7 detectors). The coldest cloud-top 10.35 µm infrared brightness temperature was -45oC, while the coldest Cloud Top Temperature derived product value was -49oC.

Sequence of GOES-17 Day Land Cloud Fire RGB, Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Cloud Top Temperature product [click to play animated GIF | MP4]

1-minute GOES-17 True Color RGB images (below) showed the Cedar Creek Fire pyroCb rising through and towering above the large pall of lower-altitude smoke.

GOES-17 True Color RGB images [click to play MP4 animation]

During the following overnight hours, a toggle between Suomi-NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (11.45 µm) images valid at 1002 UTC (below) revealed that the nighttime glow and thermal signature of larger active fires along the perimeter of the Cedar Creek Fire were still apparent, in spite of dense smoke that lingered over the area and high clouds that were beginning to move overhead from the west.

Suomi-NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (11.45 µm) images, valid at 1002 UTC on 11 September [click to enlarge]