Clear skies to the west of Oregon and California in the past two days have allowed VIIRS data (VIIRS — the Visible-Infrared Imaging Radiometer Suite flying on both Suomi-NPP and NOAA-20) to produce compelling imagery of the Sea Surface using Advanced Clear Sky Processing for Ocean (ACSPO) algorithms. VIIRS imagery is downlinked at the Direct Broadcast site at the UW-Madison; data are processed using CSPP. Purple values are just a bit cooler than 50º F; Yellow values are in the mid-60s ºF.

ACSPO estimates of SSTs are important over the Pacific Northwest because the Level 2 SST GOES-16 product is not computed near the GOES-16 limb. Level 2 Clear Sky mask is not computed out to the limb, as shown below, and GOES-16 SSTs (Full-Disk only products) are not computed out to the edge of the Clear Sky mask! So, if you want satellite-derived SSTs (GOES-17 Level 2 products are not yet widely available), Polar-Orbiting data are the way to go.

AWIPS-ready ACSPO SST files are available from via an LDM feed from CIMSS.

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Hurricane Nicholas made landfall on the Gulf Coast shortly after 0530 UTC on 14 September. It is a challenge to determine the storm center from the animation above, although deep convection is suggestive of its location. Note the collapse of deep convection as well at the end of the animation. Radar imagery, below (from this site), is helpful in placing the storm center.

MetOp-B overflew Nicholas at 0315 UTC shortly before landfall. ASCAT winds (from this site) at 0315 UTC show the circulation center very close to the shoreline. A similar image from the OSI SAF Multiplatform viewer is here.

Nicholas is embedded in very moist air. A 24-hour MIMIC Total Precipitable Water animation, below, shows the moisture plume. Heavy rain is forecast for the central Gulf Coast.

Nicholas has weakened to a Tropical Storm as of 0900 UTC on 14 September. Refer to the National Hurricane Center website for more information.

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GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation | MP4]

GOES-16 (GOES-East) Mid-level Water Vapor (6.9 µm) images (above) showed Hurricane Larry as it made landfall in Newfoundland at 0345 UTC on 11 September 2021 (causing wind gusts to 73 knots at Cape Race and 78 knots at St. Johns) — maintained hurricane intensity until 1500 UTC over the Labrador Sea — then was quickly absorbed by a large extratropical low as it progressed toward the southeast coast of Greenland on 12 September. Along the coast of Greenland, the merged remnants of Larry caused wind gusts to 63 knots at Narsarsuaq and 88 knots at Kulusuk.

Surface analyses during this period (source) are shown below.

Surface analyses [click to enlarge | MP4]

A VIIRS True Color RGB image from Suomi NPP as viewed using RealEarth (below) showed clouds associated with Post-Tropical Cyclone Larry at 1530 UTC on 11 September, when the system was centered at 54.0 N latitude, 48.2 W latitude over the Labrador Sea.

VIIRS True Color RGB image from Suomi NPP at 1530 UTC on 11 September [click to enlarge]

VIIRS True Color RGB images from Suomi NPP on 12 September (below) show the merged remnants of Larry as the large extratropical low was off the southeast coast of Greenland.

VIIRS True Color RGB images from Suomi NPP on 12 September [click to enlarge]

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JMA Himawari-8 Infrared Window (10.4 µm) images [click to play animation | MP4]

2.5-minute rapid scan JMA Himawari-8 Infrared Window (10.4 µm) images (above) displayed Typhoon Chanthu as it regained Category 5 intensity for a period of over 24 hours (track) as it moved north-northwestward between the Philippines and Taiwan during 10-11 September 2021. 

A VIIRS Infrared Window (11.45 µm) image from NOAA-20 as viewed using RealEarth (below) showed Chanthu around 17 UTC on 10 September.

VIIRS Infrared Window (11.45 µm) image from NOAA-20 [click to enlarge]

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