Wet Weather in Alaska
GOES-18 Upper Level water vapor infrared imagery, above, (source) shows a stream of upper-level moisture moving over southeastern Alaska on the east side of a cyclonic system over western Alaska on 27 January 2025. This large storm moved warm and moist air northward into Alaska; several stations tied record warm temperatures on 26 January (albeit weak records, compared to the days before the 26th), including Fairbanks and Anchorage and Kodiak Island. GOES-18 Airmass RGB images, below (from here), show the characteristic red/orange enhancement over central Alaska and the northern Gulf of Alaska expected when a strong potential vorticity anomaly is present. The green enhancement over southeast Alaska is more typical of an airmass with at least some tropical origins. (You can find a Quick Guide for the airmass RGB here, or here).
MIMIC Total Precipitable Water for the 24 hours ending 1400 UTC on 27 January 2025, below, shows a concentrated ribbon of northward-moving enhanced moisture (one might call this an atmospheric river) moving eastward, from south-central Alaska at the start of the animation to southeast Alaska at the animation’s end. The south coast of Alaska had generous rains on the 26th as this moisture source moved through.
The atmosphere river resulted in Total Precipitable Water amounts that were well above normal. The NOAA/NESDIS/OSPO Percent Of Normal field for 1200 UTC on 27 January 2025, below, from this source, showed values near 200% of normal.
The 1200 UTC/26 January 2025 sounding from Anchorage (from the handy Wyoming Sounding site) showed a TPW at 17.31 mm, 0.68 inches. (Here’s the blended TPW percent of normal for 1200 UTC on 26 January — note the exception moisture to the west of where it occurs above 24 hours later). The plot below is from the SPC Sounding Climatology page, and shows the observed maximum/mean/minimum sounder TPWs at Anchorage. The values with this system although not record breaking are certainly on the high side of the distribution for January.
This website shows microwave estimates of snowfall rate from the many polar-orbiting satellites that give excellent coverage over Alaska. Data from 0444 through 1342 UTC on 27 January 2025, below, shows heaviest snows along the coast of southeastern Alaska, and considerable snow along the Brooks Range in northern Alaska as well.
