Tropical Storm Lala becomes a Category 1 Hurricane south of the Big Island of Hawai`i
1-minute Mesoscale Domain Sector GOES-18 (GOES-West) Infrared Window and Visible images (above) showed Tropical Storm Lala as it intensified to become a Category 1 Hurricane at 1900 UTC on 15 August 2026 (GOES-18 images | NHC advisory) south of the Big Island of Hawaii. Lala exhibited a rather ragged eye that remained generally cloud-filled — and while the hurricane did not make an official landfall, its northern eyewall did pass across the far southern tip of the Big Island. An overlay of 1-minute GOES-18 GLM Flash Points revealed that there was no intermittent satellite-detected lightning activity until 2323 UTC on 15 August. In terms of wind, some RAWS sites on the Big Island reported gusts in the 60-77 mph range, and Kona International Airport reported a peak wind of 64 knots (74 mph) — with a peak gust of 140 mph occurring at the Mauna Kea summit. Highest wind gusts at other islands included 85 mph in Maui County and 74 mph in Honolulu County.
The coldest overshooting tops surrounding the eye of Lala exhibited infrared brightness temperatures in the -75 to -80 C range (brighter white pixels embedded within dark black regions) — according to a plot of rawinsonde data from Hilo on the Big Island (below), those temperatures roughly corresponded to altitudes near or just above the Forecast Surface air parcel’s Equilibrium Level (EL).
It is noteworthy that the Precipitable Water (PW) value on the Hilo sounding was 2.73 inches — which appears to be the highest PW value on record for Hilo, just eclipsing the prior record maximum value of 2.72 inches on 24 August 1961 (below).
With an unusually moist atmosphere in place, heavy rainfall amounts in excess of 43 inches occurred on the Big Island. The MIMIC Total Precipitable Water product (below) indicated that Lala was drawing rich tropical moisture northward from the Intertropical Convergence Zone (ITCZ) as the tropical cyclone developed and moved northwestward toward Hawai`i.
A sequence of storm-centered Rainfall Rate products derived using microwave data from the ATMS and AMSU instruments on a variety of polar-orbiting satellites is shown below — access to these and other Low-Earth Orbiting (LEO) satellite Direct Broadcast ground station products is discussed in this blog post.
The ample moisture of Hurricane Lala that was helping to produce the heavy rainfall was also producing snow at the summit of Mauna Kea, as documented by web camera video shortly before 0100 UTC on 16 August:
A sequence of rawinsonde data plots from Hilo (below) showed that the freezing level (labeled FZL, in cyan) was at its lowest height (15174 feet) at 0000 UTC on 16 August — which was only 1371 feet (418 meters) above the Mauna Kea summit elevation of 13803 feet. Larger snowflake aggregates falling from clouds above Mauna Kea would likely not have melted entirely before arriving at the summit.
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A 3-day animation of GOES-18 daytime True Color RGB + Nighttime Microphysics RGB images (below) displayed the northwestward trek of Lala from 14-16 August.
It is interesting to note that on 14 August, as Lala was still well southeast of the Big Island, a hazy plume of “vog” (volcanic fog) could be seen southwest of the island — which was emitted by Episode 53 of an ongoing eruption of Kilauea (the hot thermal anomaly of the volcano’s lava flow showed up as a small cluster of dark purple pixels in Nighttime Microphysics RGB imagery).