![](\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/images\/2023\/10\/231007_1625utc_suomiNPP_viirs_dayNightBand_TS_Bolaven_anim.gif\")
<\/a>Suomi-NPP VIIRS Day\/Night Band (0.7 \u00b5m) image valid at 1625 UTC [click to enlarge]<\/p><\/div>Tropical Storm Bolaven formed southeast of the Mariana Islands<\/strong><\/a> at 1200 UTC on 07 October 2023 (about 540 miles southeast of Guam, according to the initial advisory<\/strong><\/a> issued by JTWC<\/strong><\/a>). With sufficient illumination from the Moon (which was in the Waning Crescent phase, at 41% of Full), a nighttime Suomi-NPP VIIRS Day\/Night Band (0.7 \u00b5m) image valid at 1625 UTC<\/strong><\/a> (above)<\/em><\/strong> showed Bolaven as it was centered about 200 miles northeast of Chukk International Airport (METAR identifier PTKK) on Weno Island.<\/p>\n JMA<\/strong><\/a>\u00a0Himawari-9\u00a0AHI<\/strong><\/a> Infrared Window (11.2 \u00b5m) images from the\u00a0CIMSS Tropical Cyclones<\/strong><\/a>\u00a0site (below)<\/strong><\/em> showed that Bolaven was moving through an environment of low to moderate deep-layer wind shear<\/strong><\/a> — and deep convection was beginning to increase south of the storm center.<\/p>\n JMA Himawari9 Infrared Window (11.2 \u00b5m) images, with an overlay of deep-layer wind shear at 1500 UTC [click to enlarge]<\/p><\/div>A Himawari-9 Infrared \/ Water Vapor Difference product (reference<\/strong><\/a>) (below)<\/strong><\/em> highlighted areas of deep convection where overshooting tops were likely penetrating the local tropopause (yellow to red to violet enhancement)<\/em>.<\/p>\n<\/a>