Heavy Rain threat over the Samoan Islands

January 27th, 2022 |
MIMIC Total Precipitable Water over the South Pacific Ocean, 0000 UTC on 25 January – 2100 UTC on 27 January 2022 (click to enlarge)

Microwave-derived estimates of Total Precipitable Water (TPW), above, from MIMIC TPW, show an increase in moisture around the Samoan Islands to the west of 170o W. Percent of Normal mappings of blended TPW in this region, as shown below (taken from this site), show values at >150% of normal.

Percent-of-Normal TPW from the NOAA/NESDIS Blended TPW Product website, 1800 UTC on 27 January 2022 (Click to enlarge)

In anticipation of heavy rains, the National Weather Service Pacific Region requested a Mesoscale Domain (a complete list of messages is here) centered on Tutuila, the main island of American Samoa, through 1100 UTC on 28 January. An animation of GOES-17 Band 13, below, (every 5 minutes, rather than the 1-minute cadence of Mesoscale domains) overlain on top of the Level 2 Total Precipitable Water product (a product that is computed hourly for the Full Disk domain), shows a focus of convection moving westward over American Samoa and Samoa. Note the degradation of the Level 2 Product TPW that is associated with the poor functionality of the Loop Heat Pipe on GOES-17 that occurs at night. Magenta values in the TPW enhancement signify values exceeding 2″. Samoa and American Samoa are within a ribbon of exceptional moisture.

GOES-17 Mesoscale 2 domain Band 13 (Clean Window, 10.35 µm) overlain on top of clear-sky Full Disk Total Precipitable Water, 0900 – 2144 UTC on 28 January 2022 (Click to enlarge)

GOES-17 Visible Imagery, below, during the daytime, also show widespread convection moving into the Samoan waters. A benefit of the visible imagery is that surface lines of convergence that may initiate convection are apparent with the 5-minute cadence shown below; those lines are even more apparent in 1-minute imagery (shown here from 1825 – 2234 UTC)

GOES-17 Band 2 Visible (0.64 µm) Imagery, 1734 – 2144 UTC on 27 January 2022 (Click to enlarge)

Added, 28 January: the two final hours of the mesoscale domain are shown below. The axis of the deepest moisture has shifted westward through the mesoscale domain from the previous day; showers continue to develop.

GOES-17 Clean Window infrared (Band 13, 10.35 µm) and Total Precipitable Water, 0903 – 1102 UTC (Click to enlarge)

Cyclone Batsirai in the South Indian Ocean

January 27th, 2022 |

US Space Force EWS-G1 Infrared Window (10.7 µm) images [click to play animated GIF | MP4]

US Space Force EWS-G1 (formerly GOES-13) Infrared Window (10.7 µm) images (above) showed Cyclone Batsirai in the South Indian Ocean as it rapidly intensified from a Tropical Storm at 06 UTC to Category 2 storm (at 12 UTC on 27 January) and briefly exhibited a pinhole eye — and then rapidly collapsed back to Tropical Storm intensity by 00 UTC on 28 January 2022 (SATCON).

EWS-G1 Visible (0.63 µm) images  (below) also displayed the rapid formation of a pinhole eye.

US Space Force EWS-G1 Visible (0.63 µm) images [click to play animated GIF | MP4]

A map of Sea Surface Temperature from the CIMSS Tropical Cyclones site (below) showed that Batsirai had been moving over relatively warm water during its period of rapid intensification. 

Sea Surface Temperature, with the track of Cyclone Batsirai [click to enlarge]