Storm “Doris” affects the British Isles

February 23rd, 2017 |

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts in knots [click to play animation]

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts in knots [click to play animation]

Storm “Doris” affected the British Isles on 23 February 2017, producing strong winds and heavy rainfall. The mid-latitude cyclone rapidly intensified from a central pressure of 1004 hPa at 12 UTC on 22 February to 972 hPa at 12 UTC on 23 February (surface analyses) . EUMETSAT Meteosat-10 Water Vapor (6.25 µm) images (above) exhibited the “scorpion tail” signature of a sting jet (Monthly Weather Review | Wikipedia), and surface wind gusts included 58 knots at Dublin, 64 knots at Wittering and 69 knots at Valley.

The corresponding daylight Meteosat-10 High Resolution Visible (0.8 µm) images (below) revealed better detail of the various cloud structures associated with the storm.

Meteosat-10 High Resolution Visible (0.8 µm) images, with hourly surface wind gusts in knots [click to play animation]

Meteosat-10 High Resolution Visible (0.8 µm) images, with hourly surface wind gusts in knots [click to play animation]

True-color Red/Green/Blue (RGB) images from Terra/Aqua MODIS and Suomi NPP VIIRS visualized using RealEarth are shown below. EUMETSAT posted a natural-color RGB animation here.

Terra MODIS (1039 UTC), Aqua MODIS (1226 UTC) and Suomi NPP VIIRS (1248 UTC) true-color RGB images [click to enlarge]

Terra MODIS (1039 UTC), Aqua MODIS (1226 UTC) and Suomi NPP VIIRS (1248 UTC) true-color RGB images [click to enlarge]

2016 Northern Hemisphere winter / Southern Hemisphere summer solstice

December 21st, 2016 |

Meteosat-10 Visible (0.635 µm) images [click to enlarge]

Meteosat-10 Visible (0.635 µm) images [click to enlarge]

The 2016 Northern Hemisphere winter / Southern Hemisphere summer solstice occurred at 1044 UTC on 21 December. EUMETSAT Meteosat-10 Visible (0.635 µm) images (above; source) showed the westward progression of the solar terminator (which separates daylight from darkness) at 3-hour intervals.

Nearly the entire continent of Antarctica was illuminated by 24 hours of daylight, as seen on JMA Himawari-8 Visible (0.64 µm) images (below; also available as a 60 Mbyte animated GIF). Full-disk images are routinely available at 10-minute intervals from Himawari-8 (and can be available as frequently as every 5 minutes from the GOES-R series).

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

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

With the continuous daylight, Antarctic surface air temperatures from AMRC Automated Weather Stations (below; source) were seen to warm above 40ºF along the coast, and above -30ºF in the interior.

AMRC AWS station surface temperatures at 20 December (22 UTC) and 21 December (05 and 11 UTC) [click to enlarge]

AMRC AWS station surface temperatures at 20 December (22 UTC) and 21 December (05 and 11 UTC) [click to enlarge]

“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]