“Medicane” in the Mediterranean Sea

October 31st, 2016

EUMETSAT Meteosat-10 Infrared Window (10.8 um) images [click to play MP4 animation]

EUMETSAT Meteosat-10 Infrared Window (10.8 um) images [click to play MP4 animation]

A compact tropical-like cyclone (often referred to as a “medicane“) moved across the Mediterranean Sea during the 28-31 October 2016 period. EUMETSAT Meteosat-10 Infrared Window (10.8 um) images (above; also available as a 71 Mbyte animated GIF) showed the system as it developed over the Ionian Sea between Italy and Greece, initially moved southwestward, and then turned to the east where it eventually passed near the Greek island of Crete on 31 October (producing a wind gust to 52 knots at Chania’s Souda Airport LGSA and causing some wind and water damage: media story 1 | media story 2). In addition, a wind gust to 50 knots was seen on a ship report at 12 UTC on 28 October, just to the west of the storm center.

The corresponding EUMETSAT Meteosat-10 Visible (0.64 um) images (below; also available as a 17 Mbyte animated GIF) provided a more detailed look at the structure of the storm during the daylight hours of those 4 days.

EUMETSAT Meteosat-10 Visible (0.64um) images [click to play MP4 animation]

EUMETSAT Meteosat-10 Visible (0.64um) images [click to play MP4 animation]

Daily snapshots of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images viewed using RealEarth are shown below. The hazy signature of blowing dust/sand from northern Africa could be seen within the broad southeast quadrant of the storm circulation.

Suomi NPP VIIRS true-color images [click to enlarge]

Suomi NPP VIIRS true-color images [click to enlarge]

There was ample moisture available to fuel convection around the storm, as seen in the MIMIC Total Precipitable Water product (below).

MIMIC Total Precipitable Water product [click to play animation]

MIMIC Total Precipitable Water product [click to play animation]

The surface wind circulation of the medicane was well-sampled on a variety of Metop-A and Metop-B overpasses, using ASCAT plots (below) from this site.

Metop-A and Metop-B ASCAT surface scatterometer winds, 28-31 October [click to play animation]

Metop-A and Metop-B ASCAT surface scatterometer winds, 28-31 October [click to play animation]

Suomi NPP ATMS images (below; courtesy of Derrick Herndon, CIMSS) revealed the areal coverage of the small “warm core” on Channel 8 (54.94 GHz) and Channel 7 (53.596 GHz); a north-to-south oriented vertical cross section showed the depth of the thermal anomaly associated with the medicane.

Suomi NPP ATMS Channel 8 (54.94 GHz) image, 31 October at 0037 UTC [click to enlarge]

Suomi NPP ATMS Channel 8 (54.94 GHz) image, 31 October at 0037 UTC [click to enlarge]

Suomi NPP ATMS Channel 7 (53.596 GHz) image, 31 October at 0037 UTC [click to enlarge]

Suomi NPP ATMS Channel 7 (53.596 GHz) image, 31 October at 0037 UTC [click to enlarge]

 

North-to-south vertical cross section of Suomi NPP ATMS brightness temperature anomaly [click to enlarge]

North-to-south vertical cross section of Suomi NPP ATMS brightness temperature anomaly [click to enlarge]

For additional information, see this blog post from the Capital Weather Gang.

 

323 reindeer killed by lightning in Norway

August 26th, 2016

GFS model fields of surface pressure, 6-hour precipitation, 850 hPa temperature, and 10-m wind [click to play animation]

GFS model fields of surface pressure, 6-hour precipitation, 850 hPa temperature, and 10-m wind [click to play animation]

GFS model fields from this site (above) showed a relatively compact storm that was deepening as it moved northeastward across southern and central Norway on 26 August 2016.

EUMETSAT Meteosat-10 Visible (0.75 µm) and Infrared Window (10.8 µm) images (below; also available as an MP4 animation) revealed the development of thunderstorms over southern Norway during the 0900-1300 UTC period. Cloud-to-ground lightning from one of these storms is believed to have killed 323 reindeer near the southeastern corner of the Hardangervidda National Park (which is located in the center of the visible and infrared satellite images).

Meteosat-10 Visible (0.75 µm, top) and Infrared Window (10.8 µm, bottom) images, with surface reports plotted in cyan [click to play animation]

Meteosat-10 Visible (0.75 µm, top) and Infrared Window (10.8 µm, bottom) images, with surface reports plotted in cyan [click to play animation]

The coldest cloud-top infrared brightness temperatures of the thunderstorms on the 1100 UTC image was -51º C, which corresponded to an altitude of around 10.5 km on the 1200 UTC Ørland rawinsonde report (below) — looking at the individual sounding profiles, Ørland to the north of Hardangervidda was still in the moist convective environment near the center of the storm system, while Stavanger to the south began to show the drier air aloft in the wake of the northeastward-moving storm.

Rawinsonde data from Stavanger and Orland, Norway [click to enlarge]

Rawinsonde data from Stavanger and Orland, Norway [click to enlarge]

A composite of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image swaths as viewed using RealEarth (below) showed the widespread thunderstorms across southern Norway on the earlier (eastern) 1103 UTC overpass, while the later (western) 1243 UTC overpass showed the effects of the mid-level drier air that was beginning to overspread the region as the center of the parent storm system moved northeast.

Suomi NPP VIIRS true-color image swaths [click to enlarge]

Suomi NPP VIIRS true-color image swaths [click to enlarge]

Cyclone Fantala in the Indian Ocean

April 16th, 2016

Advanced Dvorak Technique intensity plot for Cyclone Fantala [click to enlarge]

Advanced Dvorak Technique intensity plot for Cyclone Fantala [click to enlarge]

A plot of the Advanced Dvorak Technique (ADT) hurricane intensity estimate (above) revealed that Indian Ocean Cyclone Fantala (19S) exhibited a period of rapid intensification on 15 April 2016, reaching Category 4 intensity with maximum sustained winds of 135 knots at 14 UTC.

EUMETSAT Meteosat-7 Infrared Window (11.5 µm) images (below) showed the formation of a well-defined eye after about 03 UTC.

Meteosat-7 Infrared (11.5 µm) images [click to play animation]

Meteosat-7 Infrared (11.5 µm) images [click to play animation]

A comparison of Meteosat-7 Infrared (11.5 µm) and DMSP-18 SSMI Microwave (85 GHz) images from the CIMSS Tropical Cyclones site (below) showed the eye structure around 15 UTC.

Meteosat-7 Infrared (11.5 µm) and DMSP-18 SSMI Microwave (85 GHz) images [click to enlarge]

Meteosat-7 Infrared (11.5 µm) and DMSP-18 SSMI Microwave (85 GHz) images [click to enlarge]

===== 18 April Update =====

Meteosat-7 Infrared Window (11.5 µm) images [click to play animation]

Meteosat-7 Infrared Window (11.5 µm) images [click to play animation]

During the 17-18 April period Cyclone Fantala reached Category 5 intensity (ADT plot), with maximum sustained winds of 150 knots (making it the strongest tropical cyclone on record in the South Indian Ocean); Fantala also became the longest-lived hurricane-strength tropical cyclone on record for that ocean basin. Meteosat-7 Infrared Window (11.5 µm) images (above) showed the storm reaching peak intensity as it moved just north of the island of Madagascar.

A comparison of Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images (below) offered a detailed nighttime view of the eye of Fantala at 2249 UTC on 17 April. Side lighting from the Moon (in the Waxing Gibbous phase, at 81% of full) helped to cast a distinct shadow within the eye, and also provided a good demonstration of the “visible image at night” capability of the Day/Night Band.

 

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

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

Storm Frank over the Northeast Atlantic Ocean

December 30th, 2015

Northeast Atlantic surface analysis maps [click to enlarge]

Northeast Atlantic surface analysis maps [click to enlarge]

Surface analysis maps over the Northeast Atlantic Ocean (above) showed the rapid intensification of an area low pressure — named Storm Frank by the UK Met Office and Met Éireann — during the 29-30 December 2015 time period. As the storm moved northward toward Iceland, the central pressure of Frank explosively deepened from 966 hPa at 06 UTC on 29 December to 928 hPa at 06 UTC on 30 December, with the tight pressure gradient producing hurricane-force winds over a large area.

EUMETSAT Meteosat-10 Visible (0.75 µm, 1-km resolution) images (below; also available as a 10-Mbyte animated GIF) depicted the well-defined center of circulation of Storm Frank during the daylight hours on 29 December, as it was intensifying south of Iceland and west of Ireland.

Meteosat-10 Visible (0.75 µm) images [click to play MP4 animation]

Meteosat-10 Visible (0.75 µm) images [click to play MP4 animation]

Meteosat-10 Infrared (10.8 µm, 3-km resolution) and Water Vapor (6.25 µm, 3-km resolution) images (below; also available as animated GIFs: 33 Mbtye Infrared and 21 Mbyte Water Vapor) showed Storm Frank as the center eventually moved over Iceland early in the day on 30 December.

Meteosat-10 Infrared (10.8 µm) images [click to play MP4 animation]

Meteosat-10 Infrared (10.8 µm) images [click to play MP4 animation]

Meteosat-10 Water Vapor (6.25 µm) images [click to play MP4 animation]

Meteosat-10 Water Vapor (6.25 µm) images [click to play MP4 animation]

As the 928 hPa low pressure moved over Iceland (below), time series plots of data from various surface stations revealed winds gusting to over 50 knots at Egilsstaðir BIEG and Akureyri BIAR; farther to the east over the British Isles, wind gusts exceeded 50 knots at Cork EICK and Stornoway EGPL, with gusts over 60 knots at Sørvágur/Vágar EKVG and Benbecula EGPL. In the North Sea off the coast of Norway, strong winds and high waves were responsible for a barge breaking free of its moorings and drifting near oil fields (media report); there was also one fatality and 2 injuries on an oil rig (media report).

Meteosat-10 Water Vapor (6.25 µm) image at 0630 UTC on 30 December, with surface station IDs [click to enlarge]

Meteosat-10 Water Vapor (6.25 µm) image at 0630 UTC on 30 December, with surface station IDs [click to enlarge]

The NWS Ocean Prediction Center created longer satellite image animations covering the entire life cycle of the storm (below).