Blowing dust across Mongolia and China

May 6th, 2021 |

Himawari-8 Dust RGB images [click to play animation | MP4]

Himawari-8 Dust RGB images [click to play animation | MP4]

JMA Himawari-8 Dust RGB images (created using Geo2Grid) covering the 48-hour period from 21 UTC on 04 May to 21 UTC on 06 May 2021 (above) revealed multiple plumes of blowing dust (brighter shades magenta/pink) which originated over parts of Mongolia — and were then transported southeastward and eastward across northeastern China.

Surface analyses from the Korean Meteorological Agency (below) showed an impressive pressure gradient between a midlatidude cyclone (moving southeastward from Mongolia into China) and high pressure moving southward behind it. Some of the airborne dust was entrained into the circulation of this low pressure system.

Surface analyses during the period from 21 UTC on 0 May to 21 UTC on 06 May [click to enlarge | MP4]

Surface analyses during the period from 21 UTC on 04 May to 21 UTC on 06 May [click to enlarge | MP4]

Rapid intensification of Super Typhoon Surigae

April 16th, 2021 |

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

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

2.5-minute interval rapid scan JMA Himawari-8 Infrared Window (10.4 µm) images (above) showed Typhoon Surigae undergoing rapid intensification (ADT | SATCON) to become a Category 4 storm as of 18 UTC on 16 April 2021.

A DMSP-16 SSMIS Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) displayed a well-defined eye, with distinct spiral bands feeding into the eyewall.

DMSP-16 SSMIS Microwave (85 GHz) image at 1944 UTC [click to enlarge]

DMSP-16 SSMIS Microwave (85 GHz) image at 1944 UTC [click to enlarge]

After sunrise, Himawari-8 “Red” Visible (0.64 µm) images (below) showed the relatively compact eye, with hints of low-level mesovortices within the eye.

JMA Himawari-8 "Red" Visible (0.64 µm) images [click to play animation]

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

===== 17 April Update =====

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

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

The prolonged period of rapid intensification continued overnight, and as of 12 UTC on 17 April Surigae had become a Category 5 Super Typhoon — 2.5-minute interval rapid scan Himawari-8 Infrared images (above) showed the well-defined eye as the storm tracked northwestward across the Philippine Sea (just east of the Philippines). A faster animation (GIF | MP4) helped to highlight the trochoidal motion (wobble) of the eye — a behavior often seen with intense tropical cyclones. The 21 UTC advisory from JTWC listed sustained winds of 165 knots (and objective intensity estimates from ADT and SATCON were around 170 knots), making Surigae the only tropical cyclone on record to reach that intensity during the month of April.



An animation of Himawari-8 Infrared images with an overlay of deep-layer wind shear (below) indicated that Surigae was moving through a region of low to moderate wind shear; the storm was also moving across very warm water (SST + OHC).

Himawari-8 Infrared images, with contours of deep-layer wind shear at 18 UTC [click to enlarge]

Himawari-8 Infrared images, with contours of deep-layer wind shear at 18 UTC [click to enlarge]

Around the time that Surigae was reaching its peak intensity, a Suomi NPP VIIRS Day/Night Band (0.7 µm) image several hours before sunrise (below) revealed concentric mesospheric airglow waves (reference) propagating away from the energetic Category 5 tropical cyclone.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

In closer view of time-matched Himawari-8 Infrared and Suomi NPP Day/Night Band images (below), a cluster of bright DNB pixels highlighted the presence of lightning activity along the inner edge of the northern eyewall.

Himawari-8 Infrared Window (10.4 µm) and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

Himawari-8 Infrared Window (10.4 µm) and Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

Cold cloud tops associated with Tropical Storm Surigae in the West Pacific

April 15th, 2021 |

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

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

2.5-minute interval rapid scan JMA Himawari-8 Infrared Window (10.4 µm) images (above) revealed intermittent cloud-top infrared brightness temperatures of -100ºC and colder (red pixels embedded within yellow-to-black inner cores) — with the coldest being -101.7ºC at 1342 UTC — within the Central Cold Cover (CCC) pattern of Tropical Storm Surigae on 15 April 2021.

A zoom-in of NOAA-20 VIIRS Infrared Window (11.45 µm) imagery at 1644 UTC as viewed using RealEarth (below) also showed 2 clusters of red -100ºC and colder pixels, with a minimum of -103.6ºC (incidentally, the coldest pixels on the 1644 UTC Himawari-8 Infrared image were -96ºC). About an hour and 15 minutes after this NOAA-20 image, Surigae was upgraded to a Category 1 typhoon (the first typhoon of the 2021 season in the West Pacific basin).

NOAA-20 VIIRSI Infrared Window (11.45 µm) image at 1644 UTC [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) image at 1644 UTC [click to enlarge]

A plot of 12 UTC rawinsonde data from Yap Island showed that the coldest air temperature was -84.7ºC at 100 hPa (16.7 km) — so an overshooting top of -100ºC or colder indicated a significant vertical ascent above the tropopause.

Plot of 12 UTC rawinsonde data from Yap Island [click to enlarge]

Plot of 12 UTC rawinsonde data from Yap Island [click to enlarge]

Tropical Depression (update: Tropical Storm Surigae) over the western Pacific

April 13th, 2021 |

Himwari-8 Clean Window (10.41 µm) Band 13 Infrared imagery, 1220 – 2050 UTC on 13 April 2021 (Click to animate)

Himawari-8 Window Channel infrared imagery (10.41 µm), above, shows a well-defined tropical disturbance (Tropical Depression #2 has become become Tropical Storm Surigae by 0900 UTC on 14 April; this website shows Pacific basin names and includes audio pronunciation examples) moving between Yap and Palau in the western Pacific to the southwest of Guam. The disturbed weather in this region has persisted for many days as it has moved towards the west-northwest, as shown in the rocking MIMIC Total Precipitable Water animation below.

10-day animation of MIMIC Total Precipitable Water over the western Pacific Ocean, 2-12 April 2021 (Click to animate)

NOAA-20 NUCAPS estimates of tropopause Heights, below, show the storm in a region with a very high tropopause, around 120 hPa. The system is moving towards a region with similarly high tropopauses.

Himawari-8 Clean Window (10.41 µm) infrared imagery overlain with NUCAPS estimates of Tropopause Heights, 1540 UTC on 13 April 2021 (Click to enlarge)

Water Vapor imagery (6.24 µm and 7.3 µm) from near sunrise of 14 April show moist air in the immediate environment surrounding the storm (Link).  Visible imagery at sunrise on 14 April, below, show strong and persistent deep convection.

Himawari-8 Visible (0.64 µm) imagery, 2027 – 2114 UTC on 13 April 2021 (Click to enlarge)

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It is interesting to note that during the ~12 hours prior to the disturbance (dubbed Tropical Invest 94W) being named Tropical Depression 02W at 12 UTC on 13 April, 2.5-minute interval Himawari-8 Visible (0.64 µm) images from 0002-0802 UTC (below) revealed a trio of low-level vorticies circulating around the incipient storm center. The northernmost vortex appeared to play a role in the initiation of a small cluster of sheared convection. While an exposed low-level circulation center is common in deteriorating highly-sheared tropical cyclones, the presence of 3 vortices during the formative stages of development is rather unusual.

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

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

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Imagery from the CIMSS Tropical Weather Site (link), below, shows the system in a region of very warm Sea Surface Temperatures and modest shear.  Strengthening is forecast as it moves towards the Philippines.

Screencaptures from the CIMSS Tropical Weather Website ca. 2100 UTC on 13 April 2021 (Click to enlarge)

 

Himawari-8 Imagery courtesy of JMA, the Japan Meteorological Agency.