Cyclone Idai makes landfall in Mozambique

March 14th, 2019 |

Meteosat-8 Infrared (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images of Cyclone Idai at 1630 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images of Cyclone Idai at 1630 UTC [click to enlarge]

Cyclone Idai — which had been slowly intensifying over warm water within the Mozambique Channel since 09 March — made landfall as a Category 2 storm along the coast of Mozambique on 14 March 2019. A toggle between Meteosat-8 Infrared Window (10.8 µm) and DMSP-17 SSMIS Microwave (85 GHz) images from the CIMSS Tropical Cyclones site (above) revealed a large and well-defined eye and eyewall structure at 1630 UTC. Idai had been rated at Category 3 intensity during 3 periods of time during its life cycle, most recently at 12 UTC on the day of landfall.

At 1911 UTC, Metop-A ASCAT winds in excess of 60  knots were sampled just west of the eyewall region (below).

Meteosat-8 Infrared Window (10.8 µm) image, with plots of Metop-A ASCAT winds at 1911 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) image, with plots of Metop-A ASCAT winds at 1911 UTC [click to enlarge]

A comparison of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP, visualized using RealEarth, is shown below.

NOAA-20 and Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 and Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

Idai had been moving through an environment of very low deep-layer wind shear — a favorable factor for maintaining its intensity — as shown in an animation of Meteosat-8 Infrared Window (10.8 µm) images (below).

Meteosat-8 Infrared Window (10.8 µm) images with contours of satellite-derived Deep-Layer Wind Shear valid at 18 UTC [click to enlarge]

Meteosat-8 Infrared Window (10.8 µm) images with contours of satellite-derived Deep-Layer Wind Shear valid at 18 UTC [click to enlarge]

The MIMIC TC product (below) suggested that Idai might have been in the early stage of an eyewall replacement cycle (ERC) just prior to making landfall. This, after completing a separate ERC during the preceding 48 hours.

MIMIC TC morphed microwave imagery [click to enlarge]

MIMIC TC morphed microwave image product [click to enlarge]

The eye of Idal was becoming cloud-filled as it approached the Mozambique coast, as seen on EUMETSAT Meteosat-8 High Resolution Visible (0.8 µm) images (below).

Meteosat-8 High Resolution Visible (0.8 µm) images [click to play animation]

Meteosat-8 High Resolution Visible (0.8 µm) images [click to play animation]

A time series of surface data from the port city of Beira FQBR (below) showed deteriorating conditions before observations ceased at 15 UTC.

Surface observation data from Beira, Mozambique [click to enlarge]

Surface observation data from Beira, Mozambique [click to enlarge]


Incidentally, an overpass of the Landsat-8 satellite on 11 March provided a 30-meter resolution view of the eye (below), soon after Idai’s first period of rapid intensification to Category 3 strength (SATCON). Surface mesovortices were apparent within the eye.

Landsat-8 False Color image of the eye of Idai on 11 March [click to play a zooming animation]

Landsat-8 False Color image of the eye of Idai on 11 March [click to play a zooming animation]

Typhoon Wutip in the West Pacific Ocean

February 21st, 2019 |

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1502 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1502 UTC [click to enlarge]

VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images from NOAA-20 at 1502 UTC (above) and from Suomi NPP at 1552 UTC (below) showed Category 2 Typhoon Wutip in the West Pacific Ocean (southeast of Guam) on 21 February 2019. With Moon in the Waning Gibbous phase (at 95% of Full), ample illumination was provided to highlight the “visible image at night” capability of the Day/Night Band.

Notable features included deep convection near the storm’s center of circulation (with the presence of subtle cloud-top gravity waves), and transverse banding along the eastern periphery of the cold central dense overcast. Bright pixels seen in the Suomi NPP Day/Night Band image were the result of clouds being illuminated by lightning activity. VIIRS images courtesy of William Straka, CIMSS.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1552 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1552 UTC [click to enlarge]

===== 22 February Update =====

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

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

Typhoon Wutip intensified to a Category 3 storm on 22 February (ADT | SATCON) — rapid scan JMA Himawari-8 Infrared Window (10.4 µm) images at 2.5 minute intervals (above) revealed cloud-top infrared brightness temperatures of -90ºC and colder (yellow pixels surrounded by darker purple) shortly after 00 UTC. Multiple convective bursts developed around the center of circulation, and evidence of eye formation was seen for a short time beginning around 1137 UTC.

Himawari-8 “Red” Visible (0.64 µm) images of Wutip (below) showed that a distinct cloud-free eye did not form during that time period.

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

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

A DMSP-17 SSMIS Microwave (85 GHz) image from the CIMSS Tropical Cyclones site (below) showed a nearly complete ring of strong convection around the eye region at 0916 UTC. A 24-hour animation of MIMIC-TC morphed microwave imagery is available here.

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

Prior to becoming a typhoon, Wutip had been moving over water with warm Sea Surface Temperatures and high Ocean Heat Content values (below).

Sea Surface Temperature and Ocean Heat Content [click to enlarge]

Sea Surface Temperature and Ocean Heat Content [click to enlarge]

===== 23 February Update =====

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

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

2.5-minute rapid scan Himawari-8 Infrared Window (10.4 µm) images (above) revealed the formation of a large and well-define eye with an annular eyewall structure as Wutip rapidly intensified (ADT | SATCON) to Category 4 Super Typhoon status on 23 February. Mesovortices could be seen rotating within the eye. Wutip became the most intense February typhoon on record in the Northwest Pacific basin.

In a toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1602 UTC (below), these mesovortices were also apparent — with the help of reflected moonlight — in the Day/Night Band.

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1604 UTC [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1604 UTC [click to enlarge]

As noted in a 21 UTC discussion from the JTWC, Wutip had a well-defined poleward outflow channel within the upper troposphere (below), which was a favorable factor for its intensification.

Himawari-8 Water Vapor (6.9 µm) images with plots of middle/upper-tropospheric derived motion winds [click to enlarge]

Himawari-8 Water Vapor (6.9 µm) images with plots of middle/upper-tropospheric derived motion winds [click to enlarge]

Tropical Disturbances in both Hemispheres

February 19th, 2019 |

Morphed Total Precipitable Water for the 24 hours ending 0100 UTC on 19 February 2019 (Click to enlarge)

Morphed Total Precipitable Water imagery (from this site) for the 24 hours ending at 0100 UTC on 19 February 2019, above, shows two Tropical disturbances spinning on either side of the Equator. Cyclone Oma in the Southern Hemisphere was northwest of New Caledonia in the Coral Sea. A second disturbance over the north Pacific, albeit very close to the Equator, was near Pohnpei and will pass near Chuuk later this week. Interests in Micronesia should pay attention to this area of disturbed weather.

Himawari-8 Clean Window imagery (10.41 µm) (courtesy JMA), below, shows the better organization of Oma in contrast to the more disorganized nature of the tropical wave over Pohnpei.

Himawari-8 AHI Clean Window (10.41 µm) Infrared Imagery, 1400 UTC 18 February – 0230 UTC 19 February 2019 (Click to play animated gif)

Refer to the CIMSS Tropical Webpage (Link) for more information on Oma. The National Weather Service on Guam is issuing statements on the tropical system in Micronesia. (From 0245 UTC on 19 February 2019, for example) (Update: This is now Tropical Depression 02W; a projected path as of 1200 UTC on 19 February is here. The current forecast has this storm achieving typhoon status late Wednesday).

Moisture Streaming towards Southern California

February 14th, 2019 |

Morphed Microwave Total Precipitable Water, 1800 UTC 13 February to 1700 UTC 14 February 2019 (Click to enlarge)

A potent Atmospheric River is affecting the California Coast on 14 February 2019. The morphed microwave imagery, above (from this site), shows rich moisture from deep in the tropics moving onto the southern California and northwest Mexican coasts.  The animation below shows the Layered Precipitable water — also a product derived from microwave imagery — for the same time period, but at 3-hour time steps (from this site).  An interesting feature is that the 850-700 hPa moisture layer is not as continuous back to the tropics as the other 3 layers.

Advected Layer Precipitable Water, 18z 13 February to 18z 14 February 2019 (Click to enlarge)

You can also infer a large influx of moisture from the low-level water vapor imagery, as shown in the short animation below from GOES-17, from 1617 UTC (just as Loop Heat Pipe issues that cause missing data were ramping down) to 1857 UTC. One might also infer a long-duration event from this animation!

GOES-17 ABI Band 10 Infrared 7.3 µm Imagery (Low-Level Water Vapor Band) from 1617 UTC to 1857 UTC on 14 February 2019 (Click to animate)

The GOES-R All-Sky Total Precipitable Water product (from this site) is as yet produced only from GOES-16 data (The Loop Heat Pipe problems have a strong impact on all Baseline products, including Legacy Profiles that are used to create Total Precipitable Water, which impact is still under investigation). The western Pacific is on the limb of this product, but it does capture the deep moisture moving towards southern California.

GOES-16 All-Sky Total Precipitable Water, 1400 UTC on 14 February 2019 (Click to enlarge)

Much of the San Diego National Weather Service Forecast Office County Warning Area is under Flood and/or Wind Warnings! See the Screen Capture below from 1121 AM Pacific Standard Time.

Warnings (as of 11:21 AM PDT on 14 February 2019) over the San Diego County Warning Area (Click to enlarge)