Hurricane Fred

August 31st, 2015

GOES-13 Visible (0.63 um) and Infrared (10.7 um) images [click to enlarge]

GOES-13 Visible (0.63 um) and Infrared (10.7 um) images [click to enlarge]

Tropical Storm Fred reached hurricane intensity east of the Cape Verde Islands late in the day on 30 August 2015.  As mentioned in the NHC discussion on the following morning, Fred was the first hurricane to pass through the Cape Verde Islands since 1892. While no central eye was apparent on GOES-13 (GOES-East) Visible (0.63 um) and Infrared (10.7 um) images at 0845 UTC (above), a DMSP SSMIS 85 GHz microwave image sourced from the CIMSS Tropical Cyclones site did reveal a small eye at 0904 UTC (below).

DMSP SSMIS 85 GHz microwave image [click to enlarge]

DMSP SSMIS 85 GHz microwave image [click to enlarge]

Later in the day, a few Tropical Overshooting Tops were analyzed using Meteosat-10 Infrared (10.8 um) imagery (below).

Meteosat-10 Infrared (10.8 um) images with overlay of Tropical Overshooting Top product [click to enlarge]

Meteosat-10 Infrared (10.8 um) images with overlay of Tropical Overshooting Top product [click to enlarge]

More information about Hurricane Fred can be found here.

Category 4 Hurricanes Kilo, Ignacio, and Jimena in the Pacific Ocean

August 30th, 2015

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

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

A composite of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from the SSEC RealEarth site (above; click to enlarge) showed Hurricanes Kilo, Ignacio, and Jimena in the central and eastern North Pacific Ocean on 29 August 2015. All three of these Category 4 North Pacific hurricanes were located east of the International Dateline, which is the first such occurrence since reliable records began in the satellite era.

An animation of GOES-15 (GOES-West) Infrared (10.7 µm) images (below; click image to play animation) showed the evolution of these 3 tropical cyclones during the 29-30 August period.

GOES-15 Infrared (10.7 µm) images [click to play animation]

GOES-15 Infrared (10.7 µm) images [click to play animation]

The MIMIC Total Precipitable Water product (below; click image to play animation) indicated that all 3 storms were easily able to tap abundant moisture from the Intertropical Convergence Zone (ITCZ).

MIMIC TPW product [click to play animation]

MIMIC TPW product [click to play animation]

Hurricane Katrina in 2005

August 28th, 2015

GOES-12 10.7 µm IR images [click to play mp4 animation]

GOES-12 10.7 µm IR images [click to play mp4 animation]

August 28 2015 is the 10-year anniversary of Hurricane Katrina achieving Category 5 status (on the Saffir-Simpson Scale) in the central Gulf of Mexico. The mp4 animation above (available here as a 490 megabyte animated gif, and on YouTube) shows the evolution of Katrina from a thunderstorm cluster in the Bahamas to a weak hurricane off the west coast of Florida to a Category 5 Hurricane in the central Gulf before weakening somewhat at landfall along the central Gulf coast. (The archive of National Hurricane Center advisories is here. The post-storm write-up is here.)

GOES-12 10.7 µm IR images [click to enlarge]

GOES-12 10.7 µm IR images [click to enlarge]

GOES-12 was in service as GOES-East during Katrina’s life, and as a GOES I-M satellite it lacked batteries to allow imaging through eclipse, which occurs as the satellite passes through the Earth’s shadow (solar panels in shadow do not provide power) in the weeks surrounding the Equinoxes. The toggle above from 28 August 2005 shows the last pre-eclipse image (0402 UTC) and the first post-eclipse image (0615 UTC); considerable organization of the storm has occurred in those two hours! GOES satellites from GOES-13 on have sufficient battery capacity to provide imagery through eclipse periods (for example, see this GOES-13 vs GOES-12 comparison during the landfall of Hurricane Ike along the Texas coast in 2008).

Katrina was featured in the CIMSS GOES Gallery back in 2005 (Link).

Tropical Storm Erika approaches the eastern Caribbean

August 26th, 2015

GOES-13 10.7 µm IR images [click to play animated GIF]

GOES-13 10.7 µm IR images [click to play animated GIF]

GOES-13 Infrared Imagery (above) for the 24 hours ending 1415 UTC on 26 August 2015 show Tropical Storm Erika approaching the Leeward Islands of the eastern Caribbean. A general increase in convection in the 24 hours shown is obvious. Visible imagery (below) from the morning of 26 August shows some overshooting tops within the central dense overcast (CDO) covering the low-level circulation. A plot of the number of overshooting tops in Erika is here (taken from this webpage). Outward-propagating gravity waves can also be seen at the top of the CDO.

GOES-13 Visible Imagery (0.63 µm) [click to play animated GIF]

GOES-13 Visible Imagery (0.63 µm) [click to play animated GIF]

Surface winds as observed by the Metop ASCAT Scatterometer early on 26 August (0056 UTC), below, show a modest circulation with winds that are mostly below tropical storm force (Added: The 1411 UTC image, bottom, shows some tropical-storm force wind flags). Dry Saharan Air Layer air should not limit intensification of Erika, but wind shear just north and west of the storm is strong (SAL and Wind Shear imagery taken from the CIMSS Tropical Cyclones site).

ASCAT Winds and GOES-13 Water Vapor IR (6.5 µm) [click to enlarge]

ASCAT Winds and GOES-13 Water Vapor IR (6.5 µm), ~0100 UTC 26 August 2015 [click to enlarge]

ASCAT Winds and GOES-13 Water Vapor IR (6.5 µm) [click to enlarge]

ASCAT Winds and GOES-13 Water Vapor IR (6.5 µm), ~1400 UTC 26 August 2015 [click to enlarge]

For the most recent forecasts on Erika’s future, see the National Hurricane Center website.