Following an extended period of slow organization, Tropical Storm Surigae (02W) formed while moving northwestward between Koror (Republic of Palau) and Yap (Federated States of Micronesia), passing near Ngulu Atoll on April 14. A broad moisture field surrounding the developing tropical circulation produced locally heavy showers across the Republic of Palau and Yap State, as well as neighboring islands. Farther north, however, only light precipitation fell across large sections of the Mariana Islands, where dryness (D0-S) and moderate short-term drought (D1-S) persisted. Meanwhile, significant drought continued to affect the northern islands in the Republic of the Marshall Islands, with Wotje remaining in extreme short-term drought (D3-S) and Kwajalein experiencing deterioration to severe drought (D2-S), compared to last week’s D1-S designation. Elsewhere, rainfall was sufficient to maintain drought-free conditions in all other areas, except Kapingamarangi (southernmost atoll in the Federated States of Micronesia), which is experiencing severe drought (D2-L) while continuing to slowly recover from acute long-term precipitation deficits.
In the Commonwealth of the Northern Mariana Islands, patchy showers embedded in a mostly dry trade wind pattern prevented further deterioration but did not provide much, if any, relief. Based on data from Guam International Airport, the Keetch-Byram Drought Index (KBDI) rose to 700 by April 14, up from 651 on April 5. KBDI values above 600 can be indicative of dryness/drought and potentially erratic fire behavior, when fires occur. From April 7-13, Guam International Airport received rainfall totaling just 0.20 inch, warranting a continuation of D0-S. On the west coast of Guam, the village of Agat received 2.04 inches during the same 7-day period. D0-S also persisted on Rota, where only 0.20 inch fell. Moderate drought (D1-S) continued across Saipan, where all reporting sites received less than an inch of rain from April 7-13.
In the Federated States of Micronesia (FSM), all islands were free of dryness and drought except Kapingamarangi, where long-term severe drought (D2-L) existed. Kapingamarangi, which endured the punishing effects of exceptional drought (D4) on crops and water supplies as recently as January 2021, has experienced slow recovery. Rainfall on Kapingamarangi has totaled at least 2 inches in four of the last 5 weeks, with more than 5 inches falling from April 7-13. Elsewhere in the FSM, most of the focus was on Tropical Storm Surigae, which led to the issuance of a Tropical Storm Warning on April 14 for Ngulu Atoll and Yap Island. Weekly (April 7-13) totals reached 8.12 inches at an observation site (North Fanif) in the Yap State municipality of Fanif and 7.76 inches on Woleai Atoll.
In the Republic of the Marshall Islands (RMI), water conservation measures remain in place on some northern islands. Wotje received 2.00 inches of rain from April 7-13 and reported a 2-week total of 3.02 inches. However, a protracted dry spell on Wotje since late 2020 warrants a continuation of extreme drought. On Kwajalein, where severe drought was introduced, there have been mostly only light rain showers since March 8-10, when 3.34 inches fell. Kwajalein’s rainfall from March 11 – April 13 totaled 3.16 inches. Although Kwajalein has high-quality water from reverse osmosis units, some neighboring islands are dependent on natural sources or water transported from Kwajalein. Ebeye, the most populous island of the Kwajalein Atoll, has experienced some water shortages, along with Mejatto and Ebadon. In addition, some crops on these islands are yellowing due to drought. Meanwhile, Majuro has turned drier in recent days, with a corresponding drop in reservoir storage. After peaking at 30.473 million gallons (85 percent of capacity) on April 3, Majuro’s storage fell to 27.218 million gallons (76 percent) by April 13. Majuro remains free of dryness, but short-term trends in rainfall and reservoir storage will need to be monitored.
Elsewhere, neither dryness nor drought is present across the Republic of Palau and American Samoa. Palau was on the periphery of nascent Tropical Storm Surigae, resulting in locally heavy showers. From April 7-13, rainfall at Palau International Airport totaled 5.54 inches. Meanwhile, slightly drier weather developed across American Samoa, with weekly totals less than 1.10 inches at all observation sites. However, earlier wetness in American Samoa currently precludes any dryness-related concerns.