Hurricane Martin, now in the north Atlantic, continues to move northeast and is expected to become a post-tropical cyclone in the next few hours. It was named a Hurricane on Wednesday, 2022-11-02 around 15UTC. Its maximum sustained winds are 85 mph (140 km/h). By the weekend, Martin’s swells will be affecting parts of Canada, the Azores, and coastal regions of western Europe. Hurricane Martin’s forecast cone is provided by the National Hurricane Center.

Meanwhile in the Gulf and Caribbean, Lisa has left much of Belize’s population to deal with its damages. Lisa upgraded to hurricane status on 2022-11-02 around 12UTC, and downgraded to tropical storm about fifteen hours later, after making landfall in Belize. As of 11-3-2022 at 15UTC, Lisa has weakened to a depression.

Animations that span several days can be easily made using RealEarth, a free tool for visualizing satellite data products. It is great for things like tracking multiple hurricanes across the Atlantic. Animation and map settings are customizable, and you can even view multiple spectral bands from satellites like GOES-16 (i.e. GOES-East).

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After a request from the National Weather Service Pacific Region, Synthetic Aperture Radar (SAR) data are available over/around Guam. These data are available at this NOAA/NESDIS website, and also via anonymous ftp from ftp.star.nesdis.noaa.gov. There will be 10 overpasses between 1 and 24 November. The first RADARSAT overpass occurred at 0839 UTC on 3 November, and it is shown above in a toggle with Himawair-8 Band 13 imagery. Very strong convection to the southwest of Guam (inferred from the cloud tops as cold as -90^oC — the purple enhancement within the white) is associated with surface winds exceeding 40 knots. A zoomed-in toggle is shown below.

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Radar estimates of hourly rainfall ending at 0839 UTC, below, (courtesy Brandon Aydlett, SOO at WFO Guam) show a large region with totals exceeding 1 inch during the previous 60 minutes, with small regions of 1.5 – 2 inches apparent.

The presence of ice in a cloud will increase SAR backscatter, and when that happens, wind speeds that are larger than observed will be indicated. This is probably happening on this day. NRCS (Normalized Radar Cross Section) imagery from this time, available here, from this website, and shown below (with computed wind speeds shown beneath that — you’ll see they match the AWIPS presentation above), show the characteristic feathery appearance that accompanies SAR detection in regions of significant cloud ice. The conclusion would be that this convection with very cold cloud tops was likely not producing very strong surface winds at 0839 UTC.

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The SAR-derived light winds that are occurring near Guam are in agreement with Advanced Scatterometer (ASCAT) data from MetopB (shown below) and MetopC (here), and from windspeed observations from AMSR-2 on GCOM-W1 (here), as taken from the NOAA ‘manati’ website.

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GOES-16 IFR Probability fields, shown above, (click here for a slower animation) combine satellite information about low clouds with Rapid Refresh model estimates of low-level saturation. On this day, regions of observed IFR conditions (that is, ceiling less than 1000 feet and/or visibilities less than 3 statute miles) are apparent over south-central Lower Michigan, northeast Indiana and northwest Ohio. IFR probability fields overlap those regions nicely. The flat IFR Probability field over central Ohio (where dense fog is also observed) is consistent with IFR Probability being computed solely with model data — because high clouds prevent the satellite from viewing low clouds.

Night Fog Brightness Temperature Difference fields, below, and Night Microphysics RGB, at bottom, can sometimes be used to detect low clouds and fog. But not on 2 November 2022! On this day, neither field showed a strong signal of fog. (Note that the high clouds over the fog in Ohio are readily apparent). If you incorporate all satellite-based fog detection products into procedures, then all products can be viewed when needed.

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GOES-R Cloud Thickness (from just before sunrise) can be used to help predict how long it will take for burn-off. Magenta values shown below are in the 600-700 foot range, that is, very thin fog that will burn off quickly. Note the region over northwestern Ohio where the cloud thickness values are bluer; cloud thickness values there are closer to 850-900 feet, and you might expect fog to linger there a bit longer. Indeed, an mp4 True-Color animation from CSPP Geosphere, shown below, shows fog after sunrise in the region over northwestern Ohio where Cloud Thickness is greatest.

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Thanks to TJ Turnage, SOO in Grand Rapids, Michigan for alerting us to this case.

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An anomalously-deep Hurricane Force low (surface analyses) moved eastward across the southern Bering Sea and eastern Aleutian Islands on 28 October 2022. GOES-18 (GOES-West) Air Mass RGB images (above) included plots of hourly surface reports — which showed some of the strong winds produced by this storm. Peak wind gusts included 75 knots / 86 mph at Dutch Harbor (PADU, at 0309 UTC on 29 October), 68 knots / 78 mph at Akutan (PAUT, at 0455 UTC on 29 October), 61 knots / 70 mph at St. George (PAPB, at 2140 UTC on 28 October, as heavy snow was being reported), 59  knots / 68 mph at Atka (PAAK, at 1645 UTC on 28 October) and 58 knots / 67 mph at Buoy 46073 (at 2200 UTC on 28 October). The 75 knot / 86 mph gust at Dutch Harbor and the 68 knot / 78 mph gust at Akutan occurred around the time that anomalously-strong 925 hPa winds were moving south-southeastward across the eastern Aleutian Islands (along the western and southwestern edge of the low pressure center).

The orange-to-red hues seen in the Air Mass RGB imagery indicated the presence of dry, ozone-rich stratospheric air within the upper portion of the atmospheric column (due to a lowering tropopause) — and AK-NAM40 model fields (below) suggested that the “dynamic tropopause” (taken to be the pressure of the PV1.5 surface) descended to the 600-675 hPa pressure level just south of the low pressure center.

Gridded NUCAPS Tropopause Height (derived using Metop-B and Metop-C CrIS/ATMS data) from the NASA SPoRT site (below) showed a narrow corridor of tropopause pressures near 600 hPa (brighter red enhancement) over and just north of the eastern Aleutians at 2108 and 2200 UTC — in general agreement with the AK-NAM40 model fields.

On the 1800 UTC Air Mass RGB image, a northwest-to-southeast oriented cross section line (Baseline B-B’) was positioned through the area of highest PV1.5 pressure values (above). The Baseline B-B’ cross section of model wind speed, potential vorticity and specific humidity (below) displayed a tropopause fold, as the dry air and high potential vorticity characteristic of stratospheric air descended southeastward around the upper-tropospheric 140-knot jet streak axis.

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