A Winter Storm Warning for Hawaii
While tropical beaches may be the first thing that comes to mind when thinking about Hawaii, it’s important to remember that the Big Island of Hawai’i has significant elevation. The highest point, Mauna Kea, is over 13,800 feet above sea level. Even though it’s the tropics, this is a high enough altitude that occasional snow can be seen during the winter months
Om 9 February 2026, conditions were ripe for a notable snowfall. Large levels of moisture coupled with an upper-level disturbance created an environment that could easily support snow at high elevations. Let’s start by looking at the moisture around Hawaii via the CIMSS MIMIC-TPW2 product. It’s clear that Hawaii lies right in the middle of the flow of an atmospheric river linking the continental United Staes to the Equator. With almost two inches of precipitable water available, the potential for a significant precipitation event is real.
Upper level support comes from an advancing trough, which can be seen in the 6.19 micron water vapor imagery from GOES-18 as the strong gradient in brightness temperatures and the general direction of flow from the southwest to the northeast. Thus, dynamic lifting is present in this very moist environment.
The Band 13 (infrared wind) imagery confirms the development of deep, moist convection. The tops of these clouds have brightness temperatures well below freezing, so snow is being formed here.
We can further confirm the cold nature of these clouds by looking at the day cloud phase distinction RGB, where the yellow clouds are indicative of thick, deep clouds in the ice phase.
We have said that it was moist. But how moist was it? The 1200 UTC sounding from Hilo (on the Big Island) can provide some insight here. This sounding was obtained from the University of Wyoming Radiosonde Archive and shows a deep layer of saturated air stretching from the surface to above the 400 mb level. The freezing level was at 640 mb (3900 m, or around 12,800 feet) and was well-below the maximum elevation of Mauna Kea.
The CIMSS Satellite blog, of course, is a strong proponent of using NUCAPS to help diagnose the thermodynamic conditions via satellite. However, this particular case exhibits some of the challenge of using satellite-based observations of temperature. The following image shows the gridded NUCAPS temperature at 700 mb. Note that the 700 mb temperature over the Big Island is right at freezing, and, givne that this is only 700 mb, the highest parts of the mountain would be well-below that critical temperature. However, the previous satellite images show that this is where the clouds are at their thickest, and precipitaiton is likely here. The colored dots representing profile quality are largely red, indicating that the NUCAPS retrieval results in this area are likely to be error-prone.
Given all of these conditions, the local weather service office issued a Winter Storm Warning for the high elevations of the Big Island. Such an event may be rare compared to the NWS offices in the upper midwest, but it’s not unheard of. Thanks to the fantastic archive at the Iowa Environmental Mesonet, it’s possible to track just how often a Winter Storm Warning is issued by a particular office. Some of these events have multiple warnings issued so it’s not trivial to connect the number of warnings to the number of significant snow events, but we can at least be sure that most years have at least one noteworthy snow event in Hawaii.
And, on a personal note, this post on Hawaiian weather is dedicated to NOAA NWS Honolulu meteorologist, native Hawaiian, and UW-Madison alumnus Will Ahue, who recently passed away. He was a friend to everyone he met, including those of us here at CIMSS. He will be deeply missed.