{"id":62451,"date":"2025-01-08T00:38:00","date_gmt":"2025-01-08T00:38:00","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=62451"},"modified":"2025-01-10T23:21:52","modified_gmt":"2025-01-10T23:21:52","slug":"a-record-wet-day-on-guam","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/62451","title":{"rendered":"A record wet day on Guam"},"content":{"rendered":"\n
\"\"<\/a>
Himawari-9 Imagery Clean Window Band 13 (10.4 \u00b5m) infrared imagery, 0000 UTC 5 January – 0000 UTC 8 January 2025 (Click to play animation)<\/figcaption><\/figure>\n\n\n\n

Antonio B. Won Pat International Airport on Guam experienced a record wet 7 January this year when 3.32″ of rain fell<\/a>, mostly between 1700 UTC\/6 January and 0500 UTC\/7 January. Himawari-9 Band 13 imagery, above, for the 3 days ending at 0000 UTC 08 January 2025, show a region of thunderstorms approaching the Marianas. A slower animation covering the times of the heavy rainfall is below; the heavy rain was fairly isolated; much of the Marianas remained dry.<\/p>\n\n\n\n

\"\"<\/a>
Himawari-9 Imagery Clean Window Band 13 (10.4 \u00b5m) infrared imagery, 1700 UTC 6 January – 0600 UTC 7 January 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n

A closer look using 10-minute Himawari-9 Infrared images centered on Guam International Airport PGUM (below) showed the series of convective storms that produced the bulk of the record-setting rainfall (plot of surface observations<\/a>). Cloud-top infrared brightness temperatures briefly reached -80\u00baC (violet pixels) with one of the convective elements.<\/p>\n

It is noteworthy that the Total Precipitable Water value of 63.33 mm (2.49 in)<\/a> derived from 7 January \/ 0000 UTC PGUM rawinsonde data exceeded the previous record TPW value of 2.34 in<\/a> for that date\/time (based on SPC climatology<\/a>).<\/p>\n

<\/a>

10-minute Himawari-9 Clean Infrared Window (10.4 \u00b5m) images, from 1800 UTC on 6 January to 0420 UTC on 7 January (courtesy Scott Bachmeier, CIMSS) [click to play animated GIF | MP4<\/strong><\/a>]<\/p><\/div>\n

10-minute Himawari-9 Visible and Infrared images (below) displayed the rapid development of a convective cell which produced a brief period of heavy rain at PGUM as it traversed the island.<\/p>\n

<\/a>

10-minute Himawari-9 Red Visible (0.64 \u00b5m, left) and Clean Infrared Window (10.4 \u00b5m, right) images, from 2100 UTC on 6 January to 0040 UTC on 7 January (courtesy Scott Bachmeier, CIMSS) [click to play animated GIF | MP4<\/strong><\/a>]<\/p><\/div>\n\n\n

The large-scale conditions that allowed the heavy rain were well-forecast. GFS forecasts of the Galvez-Davison Index (GDI) (source<\/a>) from the forecast started at 1800 UTC on 4 January 2025 are shown below, and they show a narrow tongue of higher values moving over the Marianas that corresponded with the time of the heavy rains.<\/p>\n\n\n\n

\"\"
GDI estimates from GFS output, 30- through 72-h forecasts from 0000 UTC 6 January through 1800 UTC 7 January 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n

MIMIC Total Precipitable Water (TPW) fields, below, from 0000 UTC 6 January to 0000 UTC on 8 January 2025, show abundant moisture moving over Guam (at 144o<\/sup>E Longitude, 13.4o<\/sup>N Latitude)<\/p>\n\n\n\n

\"\"
Total Precipitable Water estimates, 0000 UTC 6 January 2024 – 0000 UTC 8 January 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n

The Guam forecast office of the National Weather Service (WFO GUM) receives polar orbiting data from a Direct Broadcast antenna onsite (signals are processed by CSPP<\/a> software). True-color VIIRS imagery from ca. 0300 UTC on 7 January is shown below, and a line of convection bisecting Guam is apparent.<\/p>\n\n\n\n

\"\"
VIIRS True Color Imagery from NOAA-21 (0331 UTC) and Suomi NPP (0356 UTC) on 7 January 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n

CSPP also processes microwave imagery, and the computed MIRS<\/a> estimates of TPW are shown below. The MIRS diagnostics also show the enhanced amount of TPW over the southern Marianas as the rain fell. TPW values dropped quickly by mid-day (UTC) on the 7th<\/a> (at the end of the animation below).<\/p>\n\n\n\n

\"\"
MIRS estimates of TPW, satellite as noted, 0351 UTC on 6 January 2025 through 1156 UTC on 7 January 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n

My thanks to Landon Aydlett, WCM on Guam<\/a> for alerting me to this wet event, and to Douglas Schumacher, CIMSS, for the Direct Broadcast imagery.<\/p>\n","protected":false},"excerpt":{"rendered":"

Antonio B. Won Pat International Airport on Guam experienced a record wet 7 January this year when 3.32″ of rain fell, mostly between 1700 UTC\/6 January and 0500 UTC\/7 January. Himawari-9 Band 13 imagery, above, for the 3 days ending at 0000 UTC 08 January 2025, show a region of thunderstorms approaching the Marianas. A […]<\/p>\n","protected":false},"author":19,"featured_media":62464,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[16,73,58,79,93,131,49],"tags":[],"class_list":["post-62451","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-heavy-rain-flooding","category-himawari-9","category-metop","category-microwave","category-mirs","category-noaa-21","category-suomi_npp"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/62451","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/users\/19"}],"replies":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/comments?post=62451"}],"version-history":[{"count":17,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/62451\/revisions"}],"predecessor-version":[{"id":62550,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/62451\/revisions\/62550"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media\/62464"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=62451"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=62451"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=62451"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}