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Category 2 Hurricane Imelda passes over Bermuda

By Scott Bachmeier •

1-minute GOES-19 Visible and Infrared images with plots of 1-minute GOES-19 GLM Flash Points, from 1200-2100 UTC on 01 October; hourly METAR surface reports from Bermuda are plotted in cyan [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Visible and Infrared images (above) showed Hurricane Imelda as it intensified from a Category 1 to a Category 2 storm (at 1800 UTC) while approaching Bermuda on 01 October 2025. GLM Flash Points revealed very little satellite-detected lightning activity within the eyewall of Imelda.

About an hour prior to the beginning of the GOES-19 Visible/Infrared image animation above, a DMSP-17 SSMIS Microwave image at 1057 UTC (below) depicted the eye and eyewall of Imelda.

DMSP-17 SSMIS Microwave image at 1057 UTC on 01 October

After sunset, 1-minute GOES-19 Infrared images (below) showed Imelda as it moved across the island of Bermuda. The strongest wind gust at Bermuda/Wade International Airport (TXKF) was on the back side of Imelda, with 49 kts occurring at 0400 UTC. Soon after the core of Imelda passed over Bermuda, a series of convective bursts exhibited cloud-top infrared brightness temperatures as cold as -87ºC. Interestingly, brief clusters of GLM Flash Points were associated with some of these convective bursts northeast of Bermuda — until that point, there was a general void of lighting activity with Imelda after sunset.

1-minute GOES-19 Infrared images, from 2200 UTC on 01 October to 0500 UTC on 02 October [click to play MP4 animation]

According to a plot of rawinsonde data from Bermuda International Airport (below), the coldest cloud-top infrared brightness temperature of -87ºC corresponded to an overshoot of the Most Unstable (MU) air parcel’s Equilibrium Level (EL) of at least 1 km.

Plot of rawinsonde data from Bermuda International Airport at 0000 UTC on 02 October [click to enlarge]

Category 2 Imelda moved across a patch of warmer Sea Surface Temperature and higher Ocean Heat Content as it approached Bermuda (below) — that warmer water could have played a role in fueling the development of the aforementioned convective bursts (with lighting activity) seen in GOES-19 Infrared imagery.

Sea Surface Temperature and Ocean Heat Content along the track of Hurricane Imelda

Categories: DMSP, GLM, GOES-19, Lightning, Microwave, Tropical cyclones