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)

Flooding in Tennessee

March 28th, 2021 |

GOES-16 “Clean” Infrared Window (10.35 µm) images, with hourly Precipitation Type plotted in cyan [click to play animation | MP4]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with hourly Precipitation Type plotted in cyan [click to play animation | MP4]

GOES-16 (GOES-East) “Clean” Infrared Window (10.35 µm) images centered on Nashville (above) displayed multiple clusters of thunderstorms that moved across Tennessee during the 27 March – 28 March 2021. The coldest overshooting top infrared brightness temperatures were in the -70 to -79C range. Precipitation ended and clouds cleared as a cold front moved eastward across the state on 28 March.

Hourly images of the MIMIC TPW product (below) showed the northward surge of moisture from the Gulf of Mexico beginning early on 27 March, providing an environment conducive to heavy rainfall.

MIMIC TPW product [click to play animation | MP4]

MIMIC TPW product [click to play animation | MP4]

Plots of rawinsonde data from 00 UTC and 12 UTC on 27 March [click to enlarge]

Plots of Nashville rawinsonde data from 00 UTC and 12 UTC on 27 March [click to enlarge]

Plots of Nashville rawinsonde data from 00 UTC and 12 UTC on 27 March (above) and 28 March (below) illustrated the rapid increase in moisture on 27 March, followed by the gradual decease in the wake of the cold frontal passage.

Plots of rawinsonde data from 00 UTC and 12 UTC on 28 March [click to enlarge]

Plots of Nashville rawinsonde data from 00 UTC and 12 UTC on 28 March [click to enlarge]

 


CMORPH estimates of accumulated precipitation (available in RealEarth) are shown below, with 24-hour totals ending 23:59 on 27 March (left) and 28 March (right).  The darker purple region denotes totals of >100 mm in 24 hours.

24-hour precipitation totals ending 23:59 on 27 March (left) and at 23:59 28 March (right) 2021 (Click to enlarge)

Cyclone Habana in the South Indian Ocean

March 10th, 2021 |

US Space Force EWS-G1 Infrared Window (10.7 µm) images [click to play animation | MP4]

US Space Force EWS-G1 Infrared Window (10.7 µm) images [click to play animation | MP4]

US Space Force EWS-G1 Infrared Window (10.7 µm) images (above) displayed the well-defined eye and eyewall structure of Cyclone Habana in the South Indian Ocean on 10 March 2021. This was the second period of Category 4 intensity (ADT | SATCON) during the life cycle of Habana.

Meteosat-8 Infrared images with contours of deep-layer wind shear from the CIMSS Tropical Cyclones site (below) showed that Habana was moving through an environment of relatively low shear.

Meteosat-8 Infrared images, with contours of deep-layer wind shear [click to enlarge]

Meteosat-8 Infrared images, with contours of deep-layer wind shear [click to enlarge]

Meteosat-8 Infrared images with an overlay of 1505 UTC Metop ASCAT winds (below) depicted a fairly uniform distribution of winds within the eyewall region, as Habana developed an annular structure.

Meteosat-8 Infrared images, with a plot of Metop ASCAT winds [click to enlarge]

Meteosat-8 Infrared images, with a plot of Metop ASCAT winds [click to enlarge]

SSMIS Microwave (85 GHz) images from DMSP-16 at 1139 UTC and DMSP-18 at 2327 UTC are shown below.

DMSP-16 SSMIS Microwave (85 GHz) image at 1139 UTC [click to enlarge]

DMSP-16 SSMIS Microwave (85 GHz) image at 1139 UTC [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) image at 2327 UTC [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) image at 2327 UTC [click to enlarge]