GREMLIN radar estimates over American Samoa
GOES-18 Visible imagery, above, over the Samoan Islands, shows a variety of cloud structures moving from north to south over the Samoan Islands, especially over the smaller islands of American Samoa (Tutuila, Ofu/Olosega and Ta’u). The animation below, covering about the same time span, shows GREMLIN radar estimates. GREMLIN is a Machine-Learning tool the predicts radar returns based on ABI and GLM observations. Although it was trained on CONUS imagery, it does provide actionable information over the tropical South Pacific.
The view to the east of the Pago Pago airport, above, at 2127 UTC, shows the lower ceilings associated with the heavy rain. GREMLIN did a great job on this day of predicting onset and cessation of rains during a day when Flash Flood Warnings were issued (at 2208 UTC).
A second Flash Flood warning was issued later in the day, and the run-up to that warning is shown in the animation below, visible imagery from 0050 to 0240 UTC on 7 September, below, and GREMLIN imagery from 0040 to 0230 UTC, at bottom.
The Forecast Office in Pago Pago had a Facebook post (below) that included one of the GREMLIN images above highlighting a Flash Flood warning issued at 0249 UTC on 7 September.
Thanks to Jane Allen and Dora Meredith, NWS Pago Pago, for the AWIPS imagery!