Hurricane Danielle undergoes an Eyewall Replacement Cycle

August 28th, 2010 |
Morphed Integrated Microwave Imagery at CIMSS (MIMIC) product

Morphed Integrated Microwave Imagery at CIMSS (MIMIC) product

An animation of the Morphed Integrated Microwave Imagery at CIMSS (MIMIC) product (above) revealed that Hurricane Danielle (which had intensified into a Category 4 storm) was undergoing an Eyewall Replacement Cycle (ERC) during the 27 August – 28 August 2010 period. Note how the smaller inner eyewall deteriorated and became replaced by a much larger outer eyewall during the ERC process.

Following the ERC, GOES-13 10.7 µm IR images from the CIMSS Tropical Cyclones site (below) showed Danielle beginning the recurvature process after weakening to a Category 2 storm.

GOES-13 10.7 µm IR images

GOES-13 10.7 µm IR images

Even though Hurricane Danielle was quite far from the US East Coast (below), long period ocean swells and increasing onshore winds were creating dangerous rip currents along much of the nearshore waters and beaches from Florida to the Mid-Atlantic states.

GOES-13 10.7 µm IR image

GOES-13 10.7 µm IR image

Be sure to check out the PREDICT Field Experiment Blog for additional insights on other tropical cyclone activity in the Atlantic basin.

Unusual Double Eyewall structure in Himawari-8 Infrared Imagery of Typhoon Nangka

July 13th, 2015 |
Himawari-8 10.35 µm infrared imagery, 0540-1540 UTC on 13 July 2015 (Click to animate)

Himawari-8 10.35 µm infrared imagery, 0540-1540 UTC on 13 July 2015 (click to animate)

Himawari-8 10.35 µm infrared imagery showed an unusual (for infrared imagery) double-eyewall structure in Typhoon Nangka over the western Pacific Ocean on 13 July 2015. For such a feature to appear in infrared imagery, the secondary circulations of both the inner and outer eyewall need to be intense enough to support the downdraft/cloud-clearing necessary to create the “moats” between them. Microwave imagery of the storm, below, viewed via MIMIC (from this site), also showed the double eyewall structure quite well. This double-eyewall signature typically indicates that a tropical cyclone is experiencing an eyewall replacement cycle (ERC), which signals that a (temporary) decrease in intensity is soon to follow.

MIMIC imagery of Typhoon Nangka, 0000 - 1200 UTC on 13 July 2015 (Click to enlarge)

MIMIC imagery of Typhoon Nangka, 0000 – 1200 UTC on 13 July 2015 (click to enlarge)

Several hours later, a DMSP SSMIS 85 GHz microwave image at 1756 UTC, below, indicated that the ERC was essentially complete. Subsequently, the Joint Typhoon Warning Center slightly downgraded the intensity of Typhoon Nangka for their 21 UTC advisory. While not as well-defined as in the Himawari-8 imagery, the double-eyewall signature was still evident in the lower-resolution (4-km, vs  2-km) MTSAT-2 IR imagery (animation).

DMSP SSMIS 85 GHz microwave image and MTSAT-2 10.8 µm Infrared image (click to enlarge)

DMSP SSMIS 85 GHz microwave image and MTSAT-2 10.8 µm Infrared image (click to enlarge)

The Himawari-8 Target Sector was centered over Typhoon Nangka during this time; an IR image animation with a 2.5-minute timestep, below (courtesy of William Straka, SSEC), showed the evolution of the double eyewall signature, along with 2 pulses of storm-top gravity waves which propagated radially outward away from the center in the northern semicircle of the typhoon.

Himawari-8 10.4 µm IR channel images (click to animate large 115-Megabyte file)

Himawari-8 10.4 µm IR channel images (click to animate large 115-Megabyte file)

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]

Super Typhoon Yutu makes landfall on Tinian and Saipan

October 24th, 2018 |

Himawari-8 “Clean Window” Infrared (10.41 µm) Imagery, 0900-1540 UTC on 24 October 2018 (Click to animate)

Himawari-8 Clean Window Infrared (10.41 µm) imagery shows Super Typhoon Yutu poised to hit Tinian and Saipan in the Marianas Islands, to the northeast of Guam. The 0900 UTC Advisory from the Joint Typhoon Warning Center shows a storm with sustained winds of 145 knots, with strengthening forecast. JMA estimates a surface pressure of 905 hPa! (Link)

(Himawari data courtesy JMA and the NWS Pacific Region)

Update: Landfall on Tinian and Saipan occurred just before 1500 UTC; a closer view using 2.5 minute rapid scan Himawari-8 imagery can be seen here (station plot PGSN is Saipan, where reliable observations ceased after 1452 UTC).

Added: From William Straka, CIMSS. NOAA-20 had a fortuitous overpass, almost directly over Tinian at landfall. The Day Night Band Visible (0.7 µm) Imagery (with a full moon) and 11.45 µm infrared imagery is shown below).

NOAA-20 VIIRS Day Night Band visible (0.7 µm) imagery and I05 infrared (11.45 µm) imagery, 1551 UTC on 24 October 2018 (Click to enlarge)

CIMSS helps manage a Direct Broadcast (DB) antenna at the National Weather Service on Guam, and that antenna received both NOAA-20 and GCOM data as the eye was over, or close to, Tinian.  Microwave imagery from The Advanced Microwave Scanning Radiometer 2 (AMSR-2) on JAXA’s GCOM satellite, below, (courtesy Kathy Strabala, CIMSS) at 36.5 GHz and 89.0 GHz, reveals cloud and rainband structures that infrared imagery cannot.  In particular, the 89.0 GHz imagery suggests the formation of an outer eyewall ouside the very compact inner eye.  This typically is the start of an eyewall replacement cycle.

GCOM AMSR-2 imagery at 36.5 and 89.0 GHz, 1601 UTC on 24 October 2018 (Click to enlarge)

The DB antenna also processed data from NOAA-20, the same overpass as shown above, zoomed in over Tinian. The antenna is able to capture data over much of the western Pacific Basin, as the Day Night Band visible image shows below. A true color image from the previous overpass on Guam, 12 hours earlier, during daytime (0311 UTC on 24 October), is here.

NOAA-20 VIIRS Day Night Band visible (0.7 µm) imagery, 1544 UTC on 24 October 2018 (Click to enlarge)