Cyclone Mekunu in the northwest Indian Ocean

May 23rd, 2018 |
Meteosat-8 Infrared 10.8 µm imagery, 1630 UTC 22 May - 1715 UTC 23 May 2018 (Click to animate)

Meteosat-8 Infrared 10.8 µm imagery, 1630 UTC 22 May – 1715 UTC 23 May 2018 (Click to animate)

Cyclone Mekunu in the northwest Indian Ocean was approaching Oman and Yemen on the Arabian Peninsula on 23 May 2018, as shown in the animation above. Morphed Microwave Imagery, below, (from this site) for the 24 hours ending at 1900 UTC on 23 May 2018, shows the storm at the periphery of deep tropical moisture.  This moisture will likely lead to devastating floods in the desert regions of Oman and Yemen as the storm approaches. (News Link 1, 2 and 3).  Cyclone Chapala that affected the region in 2015 also caused devastating floods.

Microwave-based Total Precipitable Water for 24 hours ending 1900 UTC on 23 May 2018 (Click to enlarge)

Microwave imagery, below, (from this site) shows how the organization of the storm changed in the 24 hours ending around 1600 UTC on 23 May 2018.   AMSU microwave imagery for this storm can be found here (off of this website).

Morphed Microwave Imagery over Mekunu for the 24 hours ending at 1600 UTC (Click to enlarge)

Satellite intensity estimates for the storm are shown below (taken from this website). The Meteosat-8 infrared animation, above, shows a periodic increase and decay in the strong convection near the center. Satellite estimates of strength (below) show a consistent lowering of the central pressure of the storm, however; winds have consistently increased.

Satellite-based estimates of Mekunu’s central pressure (Click to enlarge)

Mekunu is traversing a region with very high Sea Surface Temperatures and modest shear. Significant weakening is not forecast.

Sea Surface Temperatures and Shear over the northwest Indian Ocean (Click to enlarge)

More information on this unusual tropical cyclone can be found at the CIMSS Tropical Weather Website (link) and the CIRA Tropical Weather Website (link).

=============== Added, 24 May 2018 ==============

Suomi-NPP overflew Mekunu at 2133 UTC on 23 May 2018, and the toggle below (between the Day Night Band and the 11.45 µm infrared;  Click here for a zoomed-in toggle between the Day Night Band and the 11.35 µm infrared image) shows the storm well-illuminated by a waxing gibbous Moon.  Strong convection with lightning is apparent north of the island of Socotra.  (VIIRS imagery courtesy Will Straka, CIMSS)

Suomi NPP VIIRS Infrared (11.45 µm) and Day Night Band Visible (0.70 µm) imagery over Mekunu, 2133 UTC on 23 May 2018 (Click to enlarge)

=============== Added, 25 May 2018 ==============

Mekunu is approaching the coast of Oman on 25 May 2018 from the southeast.  The animation below of visible (0.6 µm, left) and Infrared (10.8 µm ,right) imagery shows a compact storm with deep convection around an eye.  Microwave Imagery for the 24 hours ending at 1300 UTC on 25 May (here, from this site) suggest Mekunu is strengthening as it nears the coast. (Satellite-estimated winds and pressure also suggest strengthening near landfall).

Meteosat-8 Visible (0.6 µm, left) and Infrared (10.8 µm, right) imagery over Mekunu, 1145 UTC on 24 May to 1215 UTC on 25 May 2018 (Click to animate)

Visible Imagery from 1045 to 1430 UTC, below, suggests landfall will occur shortly after sunset east of the Oman/Yemen border.  Infrared Imagery (at bottom) shows a landfall near 1800 UTC.

Meteosat-8 Visible (0.6 µm, left) imagery over Mekunu, 1045 UTC to 1430 UTC on 25 May 2018 (Click to animate)

Meteosat-8 Infrared (10.8 µm, left) imagery over Mekunu, 1415 UTC to 1830 UTC on 25 May 2018 (Click to animate)

Surface observations from Salalah, in southern Oman (click here), show sustained tropical-storm force winds, with gusts to 60 knots, from the east for several hours today. Normal annual precipitation for the region is about 5″.

Cyclone Numa in the Mediterranean Sea

November 19th, 2017 |

Terra MODIS and Suomi NPP VIIRS true-color RGB images [click to enlarge]

Terra MODIS and Suomi NPP VIIRS true-color RGB images [click to enlarge]

A toggle between Terra MODIS and Suomi NPP VIIRS Red-Green-Blue (RGB) images, viewed using RealEarth (above), revealed the well-defined eye structure of Cyclone Numa over the Ionian Sea (between Italy and Greece) on 18 November 2017. Tracing its origin back to the remnants of Tropical Storm Rina (track), Cyclone Numa had acquired subtropical characteristics, making it a relatively rare Medicane.

EUMETSAT Meteosat-10 High Resolution Visible (0.8 µm) images (below) showed the evolution of the storm on 18 November. Plots of hourly surface reports (in metric units) are plotted on the images.

Meteosat-10 Visible (0.8 µm) images, with plots of hourly surface reports [click to play MP4 animation]

Meteosat-10 Visible (0.8 µm) images, with plots of hourly surface reports [click to play MP4 animation]

Meteosat-10 Infrared Window (10.8 µm) images (below) showed cloud-top infrared brightness temperatures around -60ºC (darker red enhancement) associated with some of the convective bursts during the 18-19 November period, as the system eventually moved inland across Greece.

Meteosat-10 Infrared Window (10.8 µm) images, with plots of hourly surface reports [click to play MP4 animation]

Meteosat-10 Infrared Window (10.8 µm) images, with plots of hourly surface reports [click to play MP4 animation]


Deadly Smog in India and Pakistan

November 9th, 2017 |

Suomi NPP VIIRS Day Night Band Visible Imagery (0.70 µm) at Night, 05, 07 and 08 November 2017 (Click to enlarge).

Suomi NPP VIIRS Visible Imagery at Night (the Day Night Band Visible Image (0.7 µm) from 5 November, 7 November and 8 November), above, and Infrared Channel Brightness Temperature Difference  (11.45 µm – 3.9 µm) on 5 November, 7 November and 8 November), below, both show the presence of fog/smog over northern Pakistan and northwestern India from 05-08 November 2017 (Suomi NPP VIIRS Imagery courtesy of William Straka, CIMSS). The Smog led the Government of Punjab to ban burning of stubble; schools in Delhi were closed.  Vehicle crashes linked to reduced visibilities have killed at least 10 people (source).  Air Quality in the region is very poor as shown in this Screen Grab from this site.

Suomi NPP VIIRS Infrared channel Brightness Temperature Difference (11.45 µm – 3.9 µm) on 05, 07, and 08 November 2017 (Click to enlarge)

An animation of Meteosat-8 Visible Imagery, below, from 03-09 November, shows little improvement in conditions in the past week.

Meteosat-8 Visible Imagery (0.6 µm) at 0300 UTC from 03 to 09 November 2017 (Click to enlarge)

Daily composites of Suomi NPP VIIRS true-color Red-Green-Blue (RGB) images from RealEarth, below, showed the areal coverage of the smog during the 03-09 November period. Surface observations at New Delhi’s Indira Gandhi International Airport indicated that the visibility remained below one statute mile — with zero visibility at times — during the 72-hour period spanning 07 November, 08 November and 09 November (animation).

Daily composites of Suomi NPP VIIRS true-color RGB images (click to enlarge)

Daily composites of Suomi NPP VIIRS true-color RGB images (click to enlarge)

Worth noting on a nighttime comparison of Suomi NPP VIIRS Infrared Brightness Difference (11.45-3.74 µm) and Day/Night Band (0.7 µm) images, below, was the appearance of a cloud shadow being cast by moonlight onto the top of the boundary layer smog/fog.

Suomi NPP VIIRS Infrared Brightness Difference (11.45-3.74 µm) and Dat/Night Band (0.7 µm) images [click to enlarge]

Suomi NPP VIIRS Infrared Brightness Difference (11.45-3.74 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

Ex-hurricane Ophelia over Ireland and the United Kingdom

October 16th, 2017 |

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

After reaching Category 3 intensity over the eastern Atlantic Ocean on 14 October, Hurricane Ophelia (storm track) rapidly underwent transition to an extratropical storm which eventually spread high winds across much of Ireland and the United Kingdom on 16 October 2017. EUMETSAT Meteosat-10 upper-level Water Vapor (6.25 µm) (above) and lower-level Water Vapor (7.35 µm) images (below) revealed the familiar “scorpion tail” signature of a sting jet (reference). Hourly wind gusts (in knots) from primary reporting stations are plotted in red.

Meteosat-10 Water Vapor (7.35 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Meteosat-10 Water Vapor (7.35 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Two sites with notable wind gusts were Cork, Ireland (67 knots at 0930 UTC) and Valley, UK (70 knots at 1500 UT), shown below. In fact, a wind gust of 103 knots (119 mph or 191 km/hour) was reported at the Fastnet Rock Lighthouse off the southwest coast of Ireland.

Time series plot of surface data from Cork, Ireland [click to enlarge]

Time series plot of surface data from Cork, Ireland [click to enlarge]

Time series plot of surface data from Valley, United Kingdom [click to enlarge]

Time series plot of surface data from Valley, United Kingdom [click to enlarge]

———————————————————————————-

Terra and Aqua MODIS true-color images [click to enlarge]

Terra and Aqua MODIS true-color images [click to enlarge]

In a toggle between Terra MODIS (overpass time around 1159 UTC) and Aqua MODIS (overpass time around 1345 UTC) true-color Red-Green-Blue (RGB) imagery (above), a somewhat hazy appearance was seen over the Irish Sea on the Terra MODIS image. This was due to an airborne plume of sand from the Sahara Desert (UK Met Office story).

In fact, blowing sand was observed about 3 hours later at Isle of Man, from 1520-1620 UTC — during that time period their surface winds gusted to 68 knots (78 mph), and surface visibility was reduced to 2.2 miles (below).

Time series plot of surface data from Isle of Man [click to enlarge]

Time series plot of surface data from Isle of Man [click to enlarge]