Cyclone Seroja

April 5th, 2021 |

Himawari-8 ‘Target Area’ clean window infrared (10.41 µm) imagery, 1224 – 2018 UTC on 5 April 2021 (Click to animate)

Himawari-8 ‘Target Area’ imagery (with a 2.5-minute timestep) on 5 April show the evolution of Cyclone Seroja over the Timor Sea northwest of Australia. (Click here for an mp4 animation). Periodic bursts of deep convection (black and white in the color-enhancement) are apparent in the center of the storm. Analyses from the CIMSS Tropical Weather Site (link) show the storm in a region of warm Sea Surface Temperatures. Modest shear is present and it is changing the convective core of the storm in the animation above from circular to elongated over the 8-hour animation. However, strengthening is forecast.

Screen capture of SSTs over the Timor Sea, wind shear, and forecast path of Cyclone Seroja (Click to enlarge)

Visible imagery at sunrise on 6 April shows the evolution of the storm.

Himawari-8 visible (0.64 µm) imagery, 2152 – 2304 UTC on 5 April 2021 (Click to enlarge)

Himawari-8 imagery courtesy JMA. You can also view satellite imagery over the area from KMA.


Update 8 April


Himawari-8 imagery (10.41 µm), below, from 0300-1610 UTC on 8 April, show a large cirrus canopy initially over Seroja eroding (You can see the 0300 and 1610 UTC images alone toggling here) Can you tell from this infrared imagery where the storm center sits?

Himawari-8 clean window infrared (10.41 µm) (full disk) imagery, 0300 – 1610 UTC on 8 April 2021 (Click to animate)

This is certainly a case where microwave imagery can (and should!) be used to better pinpoint the circulation center.  ASMU-B imagery at 89 GHz (from here), below, storm-centered at 2307 UTC 7 April, 0207 8 April and 1143 UTC on 8 April show a storm center near 18ºS, 111.5ºE at around 1200 UTC on 8 April.  Here is the Himawari-8 Clean Window infrared at 1140 UTC.  Could you place the center near its microwave-suggested center using this infrared imagery?

AMSU-B imagery at 2307 UTC 7 April, 0206 8 April and 1143 8 April. Satellite Platform as indicated in the image. Click to enlarge)

Imagery from the CIMSS Tropical Website (link), below, show that Seroja on 8 April was traversing a region of low shear.  Sea surface temperatures at present under the storm are warm; however, the projected path of the storm is towards cooler ocean waters.  There is abundant upper-level divergence over the storm and to the northwest of Seroja as well.

Maps of atmospheric wind shear, sea-surface temperatures and upper-level divergence, ca. 1500 UTC on 8 April 2021. The path of the storm, and the projected path of the storm are also noted.

Radarsat-2 Synthetic Aperture Radar (SAR) wind data (from this website), shown below, from 1054 UTC on 8 April, can also be used to infer a circulation center.

Radarsat-2 SAR Data over Seroja, 1054 UTC on 8 April 2021 (Click to enlarge)

Heavy rainfall and flooding associated with Tropical Cyclone Seroja

April 4th, 2021 |

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

The incipient circulation of Cyclone Seroja moved very slowly across the island of Timor in Indonesia during the 03 April – 04 April 2021 period — and the MIMIC Total Precipitable Water product (above) depicted very high values over that area (just northwest of Australia).

At Kupang’s El Tari Airport, precipitation amounts included 547 mm (21.5 inches) during the 48 hours ending at 00 UTC on 05 April — with the heaviest amounts of 106 mm (4.2 inches) in 6 hours and 80 mm (3.1 inches) in 3 hours occurring during the 00-06 UTC period on 04 April when the pressure was falling as Cyclone Seroja began to slowly organize and intensify (below). Flash flooding affected much of the island, with multiple deaths being reported.

Time series plot of surface observations at El Tari Airport, Kupang [click to enlarge]

Time series plot of surface observations at El Tari Airport, Kupang, Indonesia [click to enlarge]

JMA 2.5-minute interval rapid scan Himawari-8 “Clean” Infrared Window (10.4 µm) images (below) revealed a few convective bursts — with cloud-top infrared brightness temperatures of -90ºC and colder (yellow pixels embedded within darker shades of purple) — in the vicinity of Kupang (station identifier WATT) between 04 UTC on 04 April and 00 UTC on 05 April.

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

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

A NOAA-20 VIIRS Infrared Window (11.45 µm) image at 0550 UTC visualized using RealEarth (below) showed one lone -90ºC pixel within a convective burst centered just north of Kupang.

NOAA-20 VIIRS Infrared Window (11.45 µm) image at 0550 UTC on 04 April [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) image at 0550 UTC on 04 April [click to enlarge]


CMORPH estimates of 7-day precipitation (available in RealEarth) over the region show 300-400 mm over West Timor, and values exceeding 700 mm (!!) over the adjacent ocean.

7-day CMORPH accumulation of precipitation ending 0000 UTC 5 April 2021 (Click to enlarge)

Thunderstorms northeast of Guam

April 2nd, 2021 |

Himawari-8 Band 13 Clean Window infrared imagery (10.41 µm) from 2300 UTC on 1 April through 1100 UTC 2 April (Click to enlarge)

The animation above shows Himawari full-disk imagery from 2300 UTC on 1 April through 1140 UTC on 2 April and depicts a cluster of thunderstorms over the Pacific Ocean far to the northeast of Guam.  A particular challenge in diagnosing atmospheric events over the open Pacific is the lack of data.  In this case, a timely NOAA-20 overpass (around 0300 UTC), below, allowed for the use of NOAA-Unique Combined Atmospheric Processing System (NUCAPS) profiles to describe the atmosphere in and around this ongoing convection.

NOAA-20 NUCAPS Sounding Availability points, 0300 UTC on 2 April 2020 (click to enlarge)

The toggles below shows Total totals index and Tropopause heights over the Pacific Ocean around Guam and northeastward over the developing convection.  Modest instability surrounds the convective cluster (TT values from 40-44);  somewhat more unstable air (TT > 46) is diagnosed to the northwest of the convection.   Tropopause heights surrounding the convection are high, around 200 mb.  Much lower tropopause heights are diagnosed over the northern part of the domain, and the more unstable TT values are in a region where the tropopause height is sloping.

HImawari-8 Clean Window infrared imagery (10.41 µm) overlain with NUCAPS-derived Total Totals indices (with and without labels) at 0312 UTC on 2 April 2021 (click to enlarge)

Himawari-8 Clean Window infrared imagery (10.41 µm) overlain with NUCAPS-derived estimates of tropopause heights, 0312 UTC on 2 April 2021 (Click to enlarge)


Himawari-8 infrared (Clean Window, 10.41 µm) imagery and NUCAPS-derived lapse rates, 925-700 mb, 0312 UTC on 2 April 2021

NUCAPS can also show you lapse rates within the atmosphere.  It is important when viewing lapse rates to consider that the vertical resolution of NUCAPS profiles is typically not greater than 10 layers within the tropopause.  The toggle above shows lapse rates from 925-700 mb; lapse rates from 850-500 mb are shown below. These domains are is a bit larger than the domain used in showing the tropopause height and Total Totals index above.  The 925-700 mb lapse rates show two regions:  relatively weak stability, with lapse rates around 5 or 6 C/km south of 30 N Latitude, and much stronger stability (Lapse rates closer to 3 C / km ) north of that latitude, to the east of Japan.

The 850-500 mb lapse rates similarly show two general regions:  not as stable south of 30 N, much more stable east of Japan.  There is a more concentrated region of lower stability, however, along the leading edge of the sloped tropopause, at 850-500 mb compared to 925-700 mb, and the 850-500 mb values show larger lapse rates in the air to the east of Japan.  This toggle shows the 925-700 and 850-500 mb lapse rates directly.

Himawari-8 infrared (Clean Window, 10.41 µm) imagery and NUCAPS-derived lapse rates, 850-500 mb, 0312 UTC on 2 April 2021

 


This region of the Pacific Ocean is scanned by both the Advanced Himawari Imager (AHI) on JMA’s Himawari-8 satellite and the similar Advanced Meteorological Imager (AMI) on KMA’s GK2A satellite.  The animation below combines visible imagery from the two satellites at 0100, 0110, 0230 and 0400 UTC to create a pseudostereocopic image of the convection.

Himawari-8 (left) and GK2A (right) visible imagery (0.64 µm) at 0100, 0110, 0230 and 0400 UTC 2 April (Click to enlarge)


Developing (and ongoing) thunderstorms are usually locations of turbulence. The CIMSS Turbulence product, shown below for the region from 0000 UTC to 0350 UTC, and available online here, does show elevated turbulence probabilities over the convection (located over the western part of the domain shown below).

Turbulence probability plotted on top of Himawari-8 grey-scale water vapor imagery, 0000 – 0350 UTC on 2 April 2021 (Click to enlarge)

Himawari-8 imagery in this blog post courtesy of JMA; GK2A imagery in the blog post courtesy of KMA. Thanks to Brandon Aydlett, WFO Guam, for alerting us to this interesting case.

Sandstorm hits Beijing China

March 16th, 2021 |


Himawari-8 Dust RGB imagery, 0000 UTC 13 March 2021 through 2300 UTC 16 March 2021

 

 

 

The BBC reported that Beijing, the Capitol of China, was hit on 15 March by the worst sandstorm in a decade (link).  The linked-to article noted pollution levels 160 times the recommended limit! The dust and sand that overspread the city originated in Mongolia, and the dust RGB animation above (click here for an animated gif), shows dust appearing on 14 March and spreading rapidly southeast behind a propagating extratropical cyclone.  Multiple mid-layer clouds somewhat interfere with the dust/sand detection (bright red/magenta in the dust RGB shown), but the origins in Mongolia after 0600 UTC on 14 March, and the quick spread south by 1800 UTC on 15 March are apparent.

The toggle below compares Himawari-8 true-color imagery and the dust RGB at 0330 UTC on 15 March.  The dust/sand is apparent in the True Color imagery as well as in the RGB.

Himawari-8 True Color Imagery and Dust RGB, 0330 UTC on March 15 2021 (Click to enlarge)

Himawari-8 imagery is courtesy JMA.  Image processing used Geo2Grid software.  This animation of surface analyses from 13-16 March 2021 (courtesy KMA) was created by Scott Bachmeier.