Pacific Hurricane Nolo Rapidly Strengthens to Near Category 5, But Soon Weakens After
2026 continues to be an intense year for hurricanes in the eastern Pacific Ocean as Nolo became the 6th system in that basin to reach category 4 or greater during this year. Its ascent to major hurricane status was also quite fast; over the course of less than 24 hours on the 26th and 27th of September 2026, Nolo strengthened from a strong Category 1 storm all the way to the Category 4/Category 5 boundary as it propagated westward to the south of Hawaii. Let’s take a look at 24 hours of hourly geostationary Band 13 images from GOES-18 (GOES West) showing the intensification of the storm. Watch how the eye transitions from somewhat irregularly-shaped to a perfect circle at the same time the cloud top temperatures drop significantly.
One of the GOES-18 mesoscale sectors was trained on Nolo as it underwent its intensification. Here’s the one-minute mesoscale imagery from 1300-1300 UTC (3:00–3:30 AM local time). You can even see what appears to be gravity waves propagating outward along Nolo’s top, especially in the northeastern sector of the storm, which would be indicative of very strong updrafts.
The CIMSS Tropical Cyclone group, as always, has been monitoring Nolo with a suite of products. Here’s a time series of the D-MINT automated intensity estimates. According to D-MINT, Nolo briefly peaked at Category 5 before rapidly declining. D-MINT also gives us an appreciation of how long Nolo hung around as a tropical depression before it began its intensification.
The CIMSS MIMIC product is sued to provide microwave imagery from polar orbiting satellites at geostationary-like time intervals. Here is an animation from 0000 on the 27th to 0000 on the 28th (2:00 PM on the 26th to 2:00 PM on the 27th), depicting the consolidation of a strong eye wall around the center of rotation.
So what caused this rapid intensification? The the weekly sea surface anomaly plot from NOAA’s Physical Science Laboratory can provide some insight. Note how the waters south of Hawaii are 1-2 degrees above normal while this year’s El Niño rages along the Equator.
The high winds are captured by satellite observations as well. Here’s a view of the synthetic aperture radar (SAR)-derived wind speed from one of Canada’s RADARSAT polar-orbiting satellites. Remember, SAR can only detect wind speed, not wind direction, so the directional indicators in this image are from numerical weather output. This particular image is from 1634 UTC (6:34 AM local time) on the 27th, when the storm was undergoing its intensification. Observed winds in teh northwestern sector are clearly exceeding the 100 kt top end of the color scale.
Nolo did have some impacts on the southern coasts of some of the Hawaiian islands, including flash flooding, tropical-storm-level wind gusts, and heavy surf. It is anticipated that Nolo will continue to weaken as it moves into the cooler waters west and northwest of the state of Hawaii.