Moderate to heavy precipitation was reported across Southeast Alaska, but this is a wet time of the year there, and moisture deficits have been slow to improve. As a result, D0 conditions are unchanged there from last week. Farther north, no changes were supported across the D0 and D1areas in east-central Mainland Alaska despite spotty precipitation.
Episodes of heavy to excessive precipitation over the past several months have removed drought from the island chain, but a stubborn area of abnormal dryness (D0) has been hanging on across leeward locations on the Big Island. This week, a variety of indicators improved sufficiently to remove the southern reaches of the D0 area, but lingering precipitation deficits remain intact along most of the western tier of the Big Island.
At the beginning of the drought week (Wed, Sep 30 - Tue, Oct 6, 2026), Invest 93 brought showers and thunderstorms to the Marianas. Western portions of Micronesia were dominated by monsoonal showers and thunderstorms, while eastern areas experienced mostly clear to partly cloudy skies. By Friday evening, Oct 2, strong to gale-force southwesterly winds prevailed across the Marianas, largely influenced by the outgoing Tropical Storm Choi-wan (26W) and enhanced monsoon surge from the southwest. By late in the period, Choi-wan (26W) had intensified into a super-typhoon as it continued to exit the CNMI (Commonwealth of the Northern Mariana Islands) region well to the north. The southwestern monsoon surge had weakened, accompanied by slowly improving marine conditions. By early Monday evening, Oct 5, super-typhoon Choi-wan (26W) was located well east-northeast of Iwo Jima. Maximum sustained winds of 155 mph were reported by JTWC earlier in the day. Typhoon Nolo (15E) recently crossed the Date Line from the Central Pacific and was continuing to move westward at a fairly moderate clip (17 mph), with peak sustained winds of 115 mph. Tropical Depression Koguma (27W), formerly known as JTWC’s Invest 94, was centered over the northern Republic of the Marshall Islands (RMI). Koguma strengthened into a Tropical Storm shortly thereafter and by early Tuesday afternoon was centered 315 miles NNW of Kwajalein atoll near 13N/167E. Finally, in western Micronesia, the monsoon surge remained the dominant feature in the region, and was located over Palau and Yap early Monday evening, Oct 5, producing thunderstorms, showers, and gusty winds. In the South Pacific, showers embedded within the easterly wind flow continued to move across the islands from time to time. Surface high pressure to the south of American Samoa will continue to promote this easterly flow pattern, while keeping a trough to the north of the region at bay.
NASA SPoRT (GPM IMERG) satellite-based estimated rainfall totals for the past 7-days ending 12 UTC on Oct 6 indicate about 1-inch has generally fallen around Palau (though very localized 5-6 inch amounts were measured by ground-based rain gauges) and the western Federated States of Micronesia (FSM), with embedded pockets of 1-2 inches. A broad arc of 1-8 inch precipitation amounts was depicted from the CNMI eastward and southeastward to the RMI, with most of the heavier 4-8 inch totals concentrated in the vicinity of the CNMI. A large portion of the central FSM reported an inch or less of precipitation for the week. South of the equator, rainfall amounts were generally under 0.75-inch across American Samoa.
Tropical cyclones and monsoon surges ensured Guam and the CNMI had enough rainfall this past week not only to meet minimum weekly water requirements (1-inch or greater) but also monthly thresholds (4-inches or greater). According to xmACIS2 data, Dededo received the jackpot this week with 7.41 inches of rain (7 days of data). Something of note is that Dededo’s total September rainfall was 14.92 inches, which is interesting being just 10 days or so away from Columbus Day. Other totals for the week in descending order are: Guam (6.23 inches), Saipan International Airport (5.87 inches, 5 days of data), Rota Airport (5.47 inches), and Tinian (4.50 inches, 5 days of data). Guam and the CNMI remain dryness and drought-free.
The Republic of Palau measured 5.92 inches of rain at WSO Palau (Airai) and 5.01 inches of rain (6 days of data) at Koror. Given these amounts, Palau’s drought designation was improved from D1-S to D0-S this week.
Precipitation measurements taken across the Federated States of Micronesia (FSM) that reached or exceeded weekly minimum water requirements (2 inches) included (in descending order): Gilman (3.24 inches), Kapingamarangi (2.75 inches, 6 days, stays D1-S), North Fanif (2.13 inches), Ulithi (2.12 inches, 5 days), and Nukuoro (2.02 inches, 6 days). The locations that came in short of the 2-inch minimum requirement included: Rumung (1.82 inches, 6 days), Yap Island (1.62 inches, 6 days), Kosrae (1.29 inches, though only 2 days of data were available), Woleai (1.27 inches), Chuuk (0.14-inch), Lukunoch (0.04-inch, 6 days), and Pohnpei (Trace, 6 days). No data was available this week for either Fananu or Pingelap. No changes were made to any of the station designations within the FSM this week.
The Republic of the Marshall Islands (RMI) reported several stations that reached or surpassed the weekly minimum rainfall requirement this week. These include: Majuro (4.66 inches), Mili (2.97 inches, 3 days) and Kwajalein (2.21 inches). The stations that did not receive adequate rainfall this week included Jaluit (1.45 inches, 6 days), Utirik (1.25 inches), Wotje (1.13 inches, 5 days), and Ailinglaplap (1.02 inches, 6 days). All drought designations remain dryness and drought free.
In American Samoa, precipitation amounts for the week ranged between 0.40-inch at Toa Ridge to 0.50-inch at Siufaga Ridge, with an intermediate value of 0.44-inch (6 days) at the Pago Pago Airport. Tutuila retains its D0-S designation this week.
Full Summary