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.

The transition of Typhoon Atsani to a strong post-tropical storm

August 26th, 2015 |

Himawari-8 water vapor (6.2 µm) images [click to play MP4 animation]

Himawari-8 water vapor (6.2 µm) images [click to play MP4 animation]

Typhoon Atsani (which reached Category 5 intensity in the West Pacific Ocean on 19 August 2015) began to transition to a strong post-tropical storm on 25 August. JMA Himawari-8 water vapor (6.2 µm) images (above; click to play MP4 animation) showed the transformation as warm/dry air (yellow to red color enhancement) began to wrap into the western and southern portion of the storm. The animation is also available as a very large QuickTime movie (76 Mbytes) or an animated GIF (110 Mbytes).

Surface analyses from the Ocean Prediction Center (below; click to play animation) indicated that the post-tropical storm deepened to a minimum central pressure of 957 hPa at 12 UTC on 25 August, and was producing hurricane-force winds until 00 UTC on 26 August.

West Pacific Ocean surface analyses [click to play animation]

West Pacific Ocean surface analyses [click to play animation]