Super Typhoon Yutu re-intensifies to Category 5

October 26th, 2018 |

Himawari-8

Himawari-8 “Clean” Infrared Window (10.4 µm) images [click to play MP4 animation]

After making landfall in the Northern Mariana Islands on 24 October, Super Typhoon Yutu underwent eyewall replacement cycles that brought about a drop to Category 4 intensity on 25 October. However, during the day on 26 October 2018 the storm again re-intensified to Category 5 (ADT | SATCON). Himawari-8 “Clean” Infrared Window (10.4 µm) images (above) showed a fascinating variety of storm-top features: (1) outward-propagating gravity waves, (2) a quasi-stationary (in a storm-relative sense, with respect to the moving storm center) curved “notch”  — resembling a hydraulic jump — within the eastern semicircle, and (3) periodic bursts of warm/cold couplets (black/violet enhancement)  — resembling “hot tower” impulses — located well northeast of the storm center (forming around 19-20º N/137º  W) that propagated quickly northwestward. In addition, cloud-top infrared brightness temperatures of -90ºC and colder (yellow pixels embedded within darker purple shades) were seen southern eyewall during the 18-19 UTC period (1834 UTC image).

A comparison of Himawari-8 “Red” Visible (0.64 µm) and Infrared Window images during the few hours after sunrise (below) showed an eye that was partially cloud-filled with low-level mesovortices.

Himawari-8 "Red" Visible (0.64 µm, left) and "Clean" Infrared Window (10.4 µm, right) images [click to play MP4 animation]

Himawari-8 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.4 µm, right) images [click to play MP4 animation]

An animation of Himawari-8 Visible images from 2302 UTC on 26 October to 0632 UTC on 27 October (below) provides a more detailed view of the mesovortices and some of the storm-top gravity waves. As was seen on Infrared imagery, a train of quasi-stationary concentric waves formed along the “notch” feature, becoming especially pronounced around 0532 UTC.

Himawari-8

Himawari-8 “Red” Visible (0.64 µm) images [click to play MP4 animation]

A comparison of DMSP-17 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images from the CIMSS Tropical Cyclones site (below) showed Yutu around 2130 UTC.

DMSP-17 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images [click to enlarge]

Tropical Storm Michael

October 7th, 2018 |

GOES-16 "Clean" Infrared Window (10.3 µm) images [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images (above) showed deep convection associated with Tropical Depression 14 east of Belize and the Yucatan Peninsula of Mexico early in the day on 07 October 2018. There was a large area of cloud-top infrared brightness temperatures in the -80ºC to -89ºC range (shades of purple), with isolated small pockets of -90ºC or colder (yellow enhancement).

1-minute GOES-16 “Red” Visible (0.64 µm) images from the UW-AOS site (below) showed numerous convective overshooting tops.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

At 1655 UTC the system was upgraded to Tropical Storm Michael — 1-minute GOES-16 Infrared images (below) showed that deep convection persisted in the eastern semicircle of Michael during the remainder of the day.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

A hint of the elongated low-level circulation could be seen just west of the deep convection on late-day GOES-16 Visible images (below).

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

===== 08 October Update =====

NOAA-20 VIIRS Day/Night Band (0.7 µm), Infrared Window (11.45 µm) and ATMS Microwave (88 GHz) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm), Infrared Window (11.45 µm) and ATMS Microwave (88 GHz) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm), Infrared Window (11.45 µm) and ATMS Microwave (88 GHz) images at 0721 UTC (above; courtesy of William Straka, CIMSS) indicated that a well-defined convective band was wrapping around the eastern, northern and northwestern portions of the storm center (with some bright lightning streaks showing up on the DNB image in the southeastern segment of this convective band).

In a comparison of DMSP-18 SSMIS Microwave (86 GHz) and GOES-16 Infrared Window (10.3 µm) images at or shortly after 1115 UTC (below), the Microwave imagery showed a very large eye beneath the convective clusters.

DMSP-18 SSMIS Microwave (86 GHz) and GOES-16 Infrared Window (10.3 µm) images [click to enlarge]

DMSP-18 SSMIS Microwave (86 GHz) and GOES-16 Infrared Window (10.3 µm) images [click to enlarge]

Michael was upgraded to a Category 1 hurricane at 15 UTC; 1-minute GOES-16 “Red” Visible (0.64 µm) images (below) revealed abundant deep convection around the core of the storm during the 3 hours leading up to that time.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

Michael had been moving over very warm water since forming on 06 October; analyses of Ocean Heat Content and Sea Surface Temperature (below) showed that while the hurricane was forecast to briefly pass over a region of lower OHC in the far southeastern Gulf of Mexico, the remainder of its journey across the Gulf would be over water possessing modest amounts of OHC and warm SST values of 29-30ºC.

Ocean Heat Content and Sea Surface Temperature analyses, with past and forecast tracks of Michael [click to enlarge]

Ocean Heat Content and Sea Surface Temperature analyses, with past and forecast tracks of Michael [click to enlarge]

Similarly, a relatively cloud-free Terra MODIS Sea Surface Temperature product from 0343 UTC on 06 October (below) showed SST values of 84-85ºF (darker red colors) along much of the forecast path of Hurricane Michael (issued at 2100 UTC on 08 October).

Terra MODIS Sea Surface Temperature product (0343 UTC on 06 October) with Hurricane Michael forecast positions issued at 2100 UTC on 08 October [click to enlarge]

Terra MODIS Sea Surface Temperature product (0343 UTC on 06 October) with forecast positions of Hurricane Michael issued at 2100 UTC on 08 October [click to enlarge]

Hurricane Walaka

October 1st, 2018 |

GOES-15 Infrared Window (10.7 µm) images [click to play animation | MP4]

GOES-15 Infrared Window (10.7 µm) images [click to play animation | MP4]

GOES-15 (GOES-West) Infrared Window (10.7 µm) images (above) showed the formation of a well-defined eye of Hurricane Walaka during a period of rapid intensification (ADT | SATCON) from 0000-2330 UTC on 01 October 2018; Walaka was classified a Category 5 hurricane as of the 02 October 00 UTC advisory. Walaka was moving over very warm water with Sea Surface Temperatures of 30ºC.

A 1536 UTC DMSP-16 SSMIS Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) revealed a small eye (reported to be 20 nautical miles in diameter at 21 UTC).

DMSP-16 SSMIS (85 GHz) Microwave image [click to enlarge]

DMSP-16 SSMIS (85 GHz) Microwave image [click to enlarge]

A side-by-side comparison of JMA Himawari-8 and GOES-15 Infrared Window images (below) showed Walaka from 2 different satellite perspectives — the superior spatial resolution of Himawari-8 (2 km, vs 4 km for GOES-15) was offset by the much larger viewing angle. Cloud-top infrared brightness temperatures were -80ºC and colder (shades of violet) from both satellites early in the animation, but warmed somewhat into the -70 to -75ºC range by 00 UTC on 02 October.

Infrared Window images from Himawari-8 (10.3 µm, left) and GOES-15 (10.7 µm, right) [click to play animation | MP4]

Infrared Window images from Himawari-8 (10.3 µm, left) and GOES-15 (10.7 µm, right) [click to play animation | MP4]

===== 02 October Update =====

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Walaka remained classified as a Category 5 hurricane until the 15 UTC advisory on 02 October, when it was assigned Category 4 status after some weakening as a result of an overnight eyewall replacement cycle. A toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (above; courtesy of William Straka, CIMSS) showed the storm at 1240 UTC or 2:40 am local time.

GOES-15 Infrared Window (10.7 µm) images (below) showed the northward motion of Waleka. Given that the storm was forecast to pass very close to Johnston Atoll, the US Coast Guard was dispatched to evacuate personnel on Johnston Island.

GOES-15 Infrared Window (10.7 µm) images; the white circle shows the location of Johnston Atoll [click to play animation | MP4]

GOES-15 Infrared Window (10.7 µm) images; the white circle shows the location of Johnston Atoll [click to play animation | MP4]

The MIMIC-TC product (below) showed the eyewall replacement cycle during the 0000-1445 UTC period.

MIMIC-TC morphed microwave product [click to play animation]

MIMIC-TC morphed microwave product [click to play animation]

Around 1830 UTC, a toggle between GOES-15 Infrared (10.7 µm) and GPM GMI Microwave (85 GHz) images (below) showed a small eye, with evidence of a larger outer eyewall suggesting that another eyewall replacement cycle was taking place.

GOES-15 Infrared Window (10.7 µm) and GPM GMI Microwave (85 GHz) images [click to enlarge]

GOES-15 Infrared Window (10.7 µm) and GPM GMI Microwave (85 GHz) images [click to enlarge]

Hurricane Rosa

September 28th, 2018 |
GOES-15 Ifrared Window (10.7 µm, left) and GOES-17

GOES-15 Infrared Window (10.7 µm, left) and GOES-17 “Clean” Infrared Window (10.3 µm, right) images [click to play animation | MP4]

* GOES-17 images shown here are preliminary and non-operational *

GOES-15 (GOES-West) Infrared Window (10.7 µm) and GOES-17 “Clean” Infrared Window (10.3 µm) images (above) showed Hurricane Rosa on the morning of 28 September 2018, after it had rapidly intensified to Category 4 intensity overnight (ADT | SATCON). Since GOES-17 was operating in a Mode 6 scan strategy, images were available every 10 minutes (compared to every 15 minutes from GOES-15, with 30-minute gaps during Full Disk scans every 3 hours). A notable warming trend was seen in the cloud tops surrounding the eye.

A toggle between DMSP-18 SSMIS Microwave (85 GHz) and GOES-15 Infrared Window (10.7 µm) from the CIMSS Tropical Cyclones site (below) showed the bands of heavier precipitation withing the central dense overcast surrounding the eye at 1333 UTC.

DMSP-18 SSMIS Microwave (85 GHz) and GOES-15 Infrared Window (10.7 µm) images [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) and GOES-15 Infrared Window (10.7 µm) images [click to enlarge]

After sunrise, a comparison of GOES-15 Visible (0.63 µm) and GOES-17 “Red” Visible (0.64 µm) images (below) revealed an eye that was filled with low-level clouds.

GOES-15 Visible (0.63 µm, left) and GOES-17 "Red" Visible (0.64 µm, right) images [click to play animation | MP4]

GOES-15 Visible (0.63 µm, left) and GOES-17 “Red” Visible (0.64 µm, right) images [click to play animation | MP4]

An animation of the MIMIC-TC product (below) showed that Rosa went through an eyewall replacement cycle during the morning, and was downgraded to a Category 3 intensity at 15 UTC.

MIMIC-TC morphed microwave product, 0000-1545 UTC [click to enlarge]

MIMIC-TC morphed microwave product, 0000-1545 UTC [click to enlarge]