Tropical Storm Nate forms near Nicaragua

October 5th, 2017 |

GOES-16 ABI Band 2 Visible (0.64 µm) Imagery, 1127 – 1324 UTC on 5 October 2017 (Click to animate)

GOES-16 Visible Imagery, above, shows convection (imagery at 1-minute intervals) surrounding Tropical Storm Nate, just onshore in northeastern Nicaragua.

GOES-16 ABI “Clean Window” Infrared (10.3 µm) Imagery, 4 October 2017 at 2300 UTC through 1130 UTC on 5 October 2017 (Click to animate)

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

The Tropical Depression (#16) in the western Caribbean Sea has strengthened to become a minimal Tropical Storm, acquiring the name Nate. The animation from GOES-16, above, shows disorganized convection over the entire basin, stretching into the Pacific Ocean south of central America. (The sheared remains of Pacific Tropical Storm Ramon are also present south of Mexico). The animation below, from 0000-1300 UTC on 5 October 2017, shows the mid-level Water Vapor Infrared Imagery (6.95 µm) from GOES-16. Convection develops over the center of Nate, over Nicaragua, at the end of the animation.

GOES-16 ABI “Mid-Level Water Vapor” Infrared (6.95 µm) Imagery, 0000-1300 UTC on 5 October 2017 (Click to animate)

Microwave Imagery, below, from SSMI/S at around 1000 UTC on 5 October, (from this site) suggests that Nate is centered very near the coast of Nicaragua. Nate is forecast to move north into the Gulf of Mexico; its path through the northwest Caribbean suggests strengthening is possible if Nate remains far enough from land. Very warm water is present in the northwest Caribbean; that warmth extends to great depth as shown by this plot of Oceanic Heat Content; that warmth extends into the central Gulf of Mexico.

85 GHz Brightness Temperatures, 1000 UTC on 5 October 2017 (Click to enlarge)

Nate formed at a time when the Moon was Full. Thus, Suomi NPP Day Night Band Visible Imagery showed excellent illumination. The image below is from 0627 UTC on 5 October.

Suomi NPP Day Night Band Visible (0.7 µm) Imagery, 0627 UTC on 5 October 2017 (Click to enlarge)

Total Precipitable Water in advance of Nate is plentiful, as shown in the loop below (from this site). There is dry air over the continental United States, however, associated with a strong High Pressure System. Easterly winds south of that system are apparent in Scatterometer winds from early in the morning on 5 October.

MIMIC Morphed Total Precipitable Water, 1200 UTC 4 October – 1100 UTC 5 October 2017 (Click to enlarge)

Hurricane Maria makes landfall in Puerto Rico

September 20th, 2017 |

GOES-16 Visible Imagery (0.64 µm), 1017-1117 UTC, at 30-second time steps, on 20 September 2017 (Click to animate)

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

Strong Category 4 Hurricane Maria has made landfall in Puerto Rico. According to the National Hurricane Center, landfall occurred around 1035 UTC near Yabacuo on Puerto Rico’s southeast coast. The GOES-16 30-second (using overlapping mesoscale sectors) Visible Animation, above, shows the storm as it made landfall. Maria had recently completed an Eyewall Replacement Cycle as it made landfall. The animation below, using morphed microwave imagery (from this site), shows the development of an outer eyewall and subsequent erosion of the inner eyewall during the 24 hours prior to landfall.

Morphed Microwave Imagery centered on Hurricane Maria for the 24 hours prior to landfall in Puerto Rico (Click to enlarge)

GOES-16 Clean Window Infrared (10.3 µm) Imagery shows a distinct eye as the storm makes landfall. Subsequently, however, the eye filled in as it moved over the mountainous interior of Puerto Rico.

GOES-16 Infrared (10.3 µm) Imagery, 0957-1136 UTC on 20 September 2017 (Click to animate)

GOES-16 Visible (0.64 µm, left) and Infrared Window (10.3 µm, right) images (Click to play MP4 animation)

GOES-16 Visible (0.64 µm, left) and Infrared Window (10.3 µm, right) images (Click to play MP4 animation)

A 2-panel comparison of GOES-16 Visible (0.64 µm) and Infrared Window (10.3 µm) imagery during the 1020-1620 UTC time period is shown above. It can be seen that deep eyewall convection moved over much of the island as Maria made its journey across Puerto Rico.

Suomi NPP flew over Maria early in the morning on 20 September, when the storm was near St. Croix. The toggle below shows the 11.45 µm Infrared image from VIIRS and the Day Night Band Visible (0.7 µm) Imagery. The Moon on 20 September was a New Moon, so no lunar illumination was present for the Day Night Band. The eye of the storm was nevertheless apparent in the image.  A zoomed-in Infrared image over the eye is here.

Suomi NPP VIIRS 11.45 µm Infrared image from VIIRS and the Day Night Band Visible (0.7 µm) Imager, 0613 UTC on 20 September 2017 (Click to enlarge)

Suomi NPP overflew Maria again when the storm was moving offshore from Puerto Rico, and a toggle (Visible and Infrared) below shows the storm at 1724 UTC on 20 September. Click here for a zoomed-in image (Visible) over the eye.

Suomi NPP VIIRS 11.45 µm Infrared image from VIIRS and Visible (0.64 µm) Image, 1724 UTC on 20 September 2017 (Click to enlarge)

More information on Maria is available at the National Hurricane Center and at the CIMSS Tropical Weather Website.

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.

Hurricane Irma in the eastern Atlantic Ocean

September 1st, 2017 |
Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images (Click to enlarge)

Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images (Click to enlarge)

A toggle between nighttime images of Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) data at 0347 UTC (courtesy of William Straka, SSEC/CIMSS) showed a high-resolution view of the eye of Category 3 Hurricane Irma.

 

Toggle of CIMSS True Color, GOES-16 Split Window Difference (10.3 µm – 12.3 µm) field, and GOES-16 Dust RGB Product, 1315 UTC on 1 September 2017 (Click to enlarge)

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

The animation above cycles through imagery from 1315 UTC on 1 September, showing CIMSS GOES-16 True Color Imagery, The GOES-16 Split Window Difference (10.3 µm – 12.3 µm), and the GOES-16 Dust RGB (Red-Green-Blue) Product. The Split Window Difference field highlights moist air (bright red in the enhancement) to the south of Irma, and also dryer air (blue in the color enhancement), to the north. The Saharan Air Analysis, below, from the CIMSS Tropical Weather Website, corroborates the placement of the dry air to the north of Irma, and Total Precipitable Water estimates (from here) also show dry air. This dry air could influence further strengthening of the storm in the short term.

Saharan Air Layer analysis on 01 September 2017 (Click to animate)

Irma is near the eastern edge of the GLM Domain for GOES-16 in the central Test position at 89.5 W Longitude; the animation below, with GLM Group information (every 10 minutes) over ABI Band 13 (10.3 µm, every 30 minutes from the Full Disk Domain), shows little lightning near the center of Irma on 30/31 August. Lightning was more active on 1 September.

GOES-16 ABI “Clean Window” 10.3 µm Infrared Imagery, every half hour, with GLM Group Data plotted in 10-minute increments from 0000 UTC on 30 September through 1200 UTC on 1 September 2017 (Click to animate)

Satellite trends with Irma show the development of an eye structure, as seen below in the screen capture from the GOES-13 Floater (source) at 1745 UTC, and DMSP-16 SSMIS Microwave (85 GHz) at 1829 UTC on 1 September.

GOES-13 10.7 µm Infrared Imagery, 1745 UTC, 1 September 2017 (Click to enlarge)

The evolution of the eye is also apparent in the GOES-16 Visible Imagery (0.64 µm), below, from 1315-1815 UTC on 1 September 2017.

GOES-16 Visible (0.64 µm) Imagery, 1315-1815 UTC, 1 September 2017 (Click to animate)

For more information on Irma, consult the webpages of the National Hurricane Center or the CIMSS Tropical Weather Website.