Hurricane Ophelia

October 14th, 2017 |

GOES-13 Visible (0.63 µm, left) and Infrared Window (10.7 µm, right) images, with hourly surface reports (in metric units) plotted in yellow [click to animate]

GOES-13 Visible (0.63 µm, left) and Infrared Window (10.7 µm, right) images, with hourly surface reports (in metric units) plotted in yellow [click to animate]

Hurricane Ophelia — the record-tying 10th consecutive Atlantic basin hurricane of the 2017 season — reached a satellite-estimated Category 3 intensity at 15 UTC on 14 October 2017. GOES-13 (GOES-East) Visible (0.63 µm) and Infrared Window (10.7 µm) images (above) showed a well-defined circular eye as the storm moved well south of the Azores. The tweet below underscores the unusual nature of the intensity and location of Ophelia (which also occurred over unusually-cold waters).

A DMSP-17 SSMIS Microwave (85 GHz) image (below) also revealed a circular eye structure.

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

One factor that might have aided this increase of intensity was the recent passage of Ophelia through an environment of higher Maximum Potential Intensity (reference), where maximum wind speed values of 100 knots resided (below).

Maximum Potential Instability wind speed plot from 13 October, with the track of Ophelia as of 18 UTC on 14 October [click to enlarge]

Maximum Potential Instability wind speed plot from 13 October, with the track of Ophelia as of 18 UTC on 14 October [click to enlarge]

Hurricane Nate makes landfall in Louisiana and Mississippi

October 7th, 2017 |

GOES-16 Visible (0.64 µm. left) and Infrared Window (10.3 µm, right) images, with hourly surface reports plotted in yellow [click to play MP4 animation]

GOES-16 Visible (0.64 µm. left) and Infrared Window (10.3 µm, right) images, with hourly surface reports plotted in yellow [click to play MP4 animation]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

1-minute interval Mesoscale Sector GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the large central dense overcast (which exhibited cloud-top infrared brightness temperatures of -80ºC and colder, violet colors, and at times -90ºC and colder, yellow enhancement) and subsequent smaller convective bursts associated with Hurricane Nate on 07 October 2017.

After having moved north-northwestward at speeds up to 24 mph — quite possibly the fastest-moving tropical cyclone on record in the Gulf of Mexico — Nate made its initial landfall (as a Category 1 storm) in Louisiana near the mouth of the Mississippi River at 00 UTC on 08 October 2017 [note: Nate’s second landfall was around 0530 UTC near Biloxi, Mississippi]. A few reports of damaging winds and tornadoes were noted ahead of and during Nate’s landfall; a listing of other wind gusts can be seen here.

Earlier in the day, DMSP-17 SSMIS Microwave (85 GHz) imagery was hinting at the development of a closed eye structure beneath the central dense overcast seen on GOES-13 Infrared Window (10.7 µm) imagery (below).

GOES-13 Infrared Window (10.7 µm) and DMSP-17 SSMIS Microwave (85 GHz) images around 1215 UTC [click to enlarge]

GOES-13 Infrared Window (10.7 µm) and DMSP-17 SSMIS Microwave (85 GHz) images around 1215 UTC [click to enlarge]

Even though Nate passed over very warm water in the Gulf of Mexico (below), the fast forward motion of the storm limited its ability to take advantage of those warm waters and rapidly intensify.

Sea Surface Temperature and Ocean Heat Content analyses from 06 October, with an overlay of the 07 October path of Hurricane Nate ending at 12 UTC [click to enlarge]

Sea Surface Temperature and Ocean Heat Content analyses from 06 October, with an overlay of the 07 October path of Hurricane Nate ending at 12 UTC [click to enlarge]

Tropical Storm Maria upgraded to Hurricane Maria in the central Atlantic

September 16th, 2017 |

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to animate]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

On 16 September 2017, GOES-16 “Clean” Infrared Window (10.3 µm) images (above) showed the early stages of development of Tropical Storm Maria in the central Atlantic Ocean (located at 12.3 ºN latitude, 52.6 ºW longitude at 2100 UTC). Convective bursts exhibited cloud-top infrared brightness temperatures in the -77 ºC to -79 ºC range (brighter white enhancement). The hourly surface report from TBPB (along the left edge of the images) is Bridgetown in Barbados.

Unfortunately, the initial National Hurricane Center forecast track (below) takes Maria to Major Hurricane intensity over or near islands that were recently heavily impacted by Hurricane Irma. Maria is forecast to remain in an environment of low wind shear and move over waters characterized by warm SST and high OHC values (source), which all favor intensification.

Initial NHC forecast track [click to enlarge]

Initial NHC forecast track [click to enlarge]

===== 17 September Update =====
GOES-16 Visible (0.64 µm, left) and Infrared Window (10.3 µm, right) images [click to animate]

GOES-16 Visible (<strong0.64 µm, left) and Infrared Window (10.3 µm, right) images [click to animate]

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Widow (10.3 µm) images (above) revealed a steady trend of organization during the day on 17 September, which allowed Maria to intensify to Category 1 Hurricane status at 2100 UTC. Note the large convective burst which expanded just west of the center of circulation after 1700 UTC — cloud-top infrared brightness temperatures were impressively cold, in the -80ºC to -89ºC range (violet shades of color enhancement).

===== 18 September Update =====
GOES-16 Visible (0.64 µm, left) and Infrared Window (10.3 µm, right) images [click to animate]

GOES-16 Visible (0.64 µm, left) and Infrared Window (10.3 µm, right) images [click to animate]

A GOES-16 Mesoscale Sector was positioned over Hurricane Maria, providing imagery at 1-minute intervals — Visible (0.64 µm) and Infrared Window (10.3 µm) images (above) captured the formation of an obvious eye feature beginning around 1615 UTC. Maria rapidly intensified (CIMSS SATCON) from a Category 1 to a Category 4 Hurricane east of Le Lamentin, Martinique (TFFF) during this daylight sequence of 1-minite images; the eye then went on to approach the small island of Dominica (TDCF is the identifier of their Canefield Airport) — and in fact Maria was upgraded to Category 5 intensity as the eye was just east of Dominica at 00 UTC on 19 September (NHC advisory). AWIPS imagery of the 1-minute GOES-16 Infrared data is available here.

This small-diameter “pinhole eye” was also evident earlier in the day on DMSP microwave imagery at 1040 UTC, and again at 1843 UTC.

Hurricane Irma

September 8th, 2017 |

GOES-16 “Clean Window” Imagery (10.3 µm) every six hours from 1500 UTC 31 August to 0900 UTC 8 September, centered on Irma (Click to animate)

GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing

The animation above shows Irma every 6 hours from 31 August through 8 September, using the GOES-16 “Clean Window” Imagery (10.3 µm). The animation below shows the GOES-16 Upper-Level Water Vapor Infrared Imagery (6.19 µm) (Click here for the Low-Level Water Vapor Infrared Imagery — 7.34 µm). All three animations show a gradual increase in the size of the storm. The structure of the storm at the very end suggests a slight weakening, most likely temporary, of Irma.

GOES-16 “Low-Level Water Vapor” Infrared Imagery (6.19 µm) every six hours from 1500 UTC 31 August to 0900 UTC 8 September, centered on Irma (Click to animate)

The recent slight weakening of Irma is mostly likely related to an Eyewall Replacement Cycle, shown in the Microwave Imagery below (from this site). In an Eyewall Replacement, an outer eyewall develops around the inner eyewall, after which time the inner eyewall will diminish and then dissipate, usually but not always weakening the storm. The outer eyewall will then contract, usually as the storm re-intensifies (if other environmental parameters that govern strengthening — Sea Surface Temperatures, Moisture, Shear — are favorable).

Morphed Microwave Imagery over Irma for the 48 hours ending 1200 UTC on 8 September 2017 (Click to enlarge)

The imagery below shows a recent 8-hour animation of Irma and Katia using the GOES-16 Clean Window (10.3 µm) Channel. The Inner Core of Irma looks a bit more ragged compared to previous days, although excellent outflow continues, and very little dry air is apparent. Katia in the southwest Gulf of Mexico is occasionally presenting an eye.

GOES-16 “Clean Window” Imagery (10.3 µm) 0717-1522 UTC on 8 September (Click to animate)

For more on this system, please consult the National Hurricane Center Website, or the SSEC/CIMSS Tropical Weather Website.