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]

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)

Eruption of Mount Etna

March 24th, 2021 |

Meteosat-11 Ash Height images [click to play animation | MP4]

Meteosat-11 Ash Height images [click to play animation | MP4]

EUMETSAT Meteosat-11 Ash Height retrievals from the NOAA/CIMSS Volcanic Cloud Monitoring site (above) showed that an eruption of Mount Etna in Sicily, Italy on 24 March 2021 produced an ash cloud which rose to heights of 7-8 km (darker shade of green).

The corresponding Meteosat-11 Ash Loading images are shown below — ash loading appeared to be light to moderate within much of the volcanic cloud.

Meteosat-11 Ash Loading images [click to play animation | MP4]

Meteosat-11 Ash Loading images [click to play animation | MP4]

Ash Loading values retrieved using Suomi NPP VIIRS data at at 1200 UTC (below) were notably higher than those from Meteosat-11, given the higher spatial resolution and additional spectral band data available from the VIIRS instrument.

Suomi NPP VIIRS Ash Loading at 1200 UTC [click to enlarge]

Suomi NPP VIIRS Ash Loading at 1200 UTC [click to enlarge]

A toggle between VIIRS True Color RGB images from NOAA-20 and Suomi NPP as viewed using RealEarth (below) revealed hues of tan to light brown within the volcanic plume, further supporting the presence of an elevated ash content.

VIIRS True Color RGB images from NOAA-20 and Suomi NPP [click to enlarge]

VIIRS True Color RGB images from NOAA-20 and Suomi NPP [click to enlarge]

Monitoring severe weather as it happens

March 17th, 2021 |

NUCAPS/MADIS Lifted Index, GLM Group Density, GOES-16 Band 13 Infrared Imagery, and ProbSevere polygons, all at ~0939 UTC on 17 March 2021 (Click to enlarge) All imagery from RealEarth

When NOAA’s Storm Prediction Center issues a High Risk of severe weather (below), people sit up and take notice. Are there easily accessible tools to monitor the state of the atmosphere in/around a region of expected severe weather?

The toggle above shows products (early in the morning on 17 March — at 439 AM CDT) in RealEarth that can help. NOAA-Unique Combines Atmospheric Processing System (NUCAPS)/MADIS (Meteorological Assimilation Data Ingest System) Lifted Indices combine tropospheric information from NUCAPS profiles with lower-tropospheric/surface information from MADIS to create Lifted Index fields, twice daily. These fields are generated using HEAP (Hyper-spectral Enterprise Algorithm Package) software (incorporated into CSPP — the Community Software Processing Package) at the UW-CIMSS Direct Broadcast site. A Suomi-NPP (or NOAA-20) overpass will quickly yield stability information. Today’s afternoon Suomi-NPP overpasses occurs around 1730 UTC (east of the High Risk area) and 1915 UTC (Link, from this site.) The toggle above also includes GOES-16 Band 13 infrared (Clean Window, 10.3 µm) information, GLM Group Density, and NOAA/CIMSS ProbSevere (ProbSevere has a stand-alone RealEarth-based site here).  All of these products are useful in monitoring this evolving, dangerous event.   As is often the case, the strongest convection was occurring at 0939 UTC along the edges of the most unstable air, that is, in the instability gradient.

People within the region of elevated risk of Severe Weather on 17 March 2021, especially the region High Risk, should pay especial attention to the weather.

NOAA Storm Prediction Center Risk assessment for 17 March 2021, issued 1300 UTC on 17 March (Click to enlarge)


Added: the Geosphere site (link) gives rapid access to GOES-16 imagery (including mesoscale sectors) and can be used to monitor this evolving situation.


The afternoon image of stability is shown below.

NUCAPS/MADIS Lifted Index, GLM Group Density, and GOES-16 Band 13 Infrared Imagery, all at ~1830 UTC on 17 March 2021 (Click to enlarge) All imagery from RealEarth