There were no changes made in Alaska this week.
Heavy precipitation fell across much of Hawaii with flash flooding occurring on several islands. Molokai and Lanai had all abnormal dryness removed. Maui and the Big Island saw nearly full one-category improvements with some isolated areas that missed out on the heavy precipitation.
The Marianas experienced a very dry week while heavier but still below-normal rainfall was observed in western Micronesia and Palau. Existing drought in these areas either persisted or intensified, and abnormal dryness developed on Koror in Palau. Farther east and south, most of the U.S. Affiliated Pacific Islands recorded moderate to heavy rainfall, abetting improvement in most locations with antecedent dryness or drought, especially in the Marshalls.
A few tenths of an inch of rain fell on Koror, Palau. For the first two weeks of May, only 1.1 inches of rain was reported, which is 20 percent of normal. Since the beginning of the year, March was much drier than normal, but higher than normal amounts fell during the other months. These amounts are deceptive, however, since the high totals resulted from heavy rainfall events that occurred in short periods of time, reducing the effectiveness of the precipitation in recharging environmental moisture. Given this and the extremely dry start to May, abnormal dryness (D0) has been introduced this week.
A few tenths of an inch of rain at best fell on the Marianas, bringing totals for the first two weeks of May to between 0.5 and 1.0 inch. Since the start of 2024, rainfall has been considerably below normal, and well below the amount needed to keep up with environmental and human demand (4 inches per month, or 17.8 inches for January – mid-May). Year-to-date totals at Rota (10.2 inches) are just over half of normal, and totals at Saipan (8.3 inches) are under half of what is needed to keep pace with demand. In Guam, the 4.5-month total of near 13.6 inches is 76 percent of normal and just 4 inches less than normal, but of that total, 5.75 inches (about 42 percent) fell in one day, substantially reducing its effectiveness in recharging the moisture budget. Given these numbers, the assessment at Rota deteriorated to extreme drought (D3) this week, matching the assessment at Saipan (D3). Guam remained in severe drought (D2).
In western Micronesia, a few tenths of an inch of rain fell on Ulithi while heavier showers dropped larger amounts on Yap (2.5 inches, with about an inch on the last day of the period). Exceptionally dry conditions date back to November 2023 at both of these sites. Yap and Ulithi observed 24.0 and 21.7 inches of rain in the 6 ½ months since, which is 52 and 56 percent of normal, respectively. Exceptional dryness (D4) continued at both locations.
Along the central tier of Micronesia, about 1.6 inches of rain fell on Chuuk Lagoon this past week while the locations farther south (Lukonor, Nukuoro, and Kapingamaringi) reported slightly over 3 inches. At Chuuk, over 4.2 inches has fallen during the first half of May, followng April amounts exceeding one foot, bringing an end to the abnormal dryness (D0) that had been assessed there. Antecedent conditions were wetter farther south, with 13.1 to 18.6 inches of rain recorded during April followed by 4.0 to 6.6 inches for the first two weeks of May. Impactful dryness is unlikely at these sites in the near future.
Abundant rainfall continued in eastern Micronesia. Kosrae reported 2.1 inches this past week while 4.6 inches dropped on Pohnpei, bringing totals for the first two weeks of May to 8.3 and 7.8 inches, respectively. Earlier this year, February-April rainfall totals ranged from 45 to 50 inches, so impactful dryness is unlikely in the foreseeable future.
Wotje in the northeastern Marshalls was slightly wetter than normal this past week. About 1.7 inches of rain fell on Wotje, following a first week of May that was without any precipitation. Rainfall at Wotje has been slightly below normal since the start of April (5.05 inches, 88 percent of normal), and less than the amount consistently needed to keep pace with environmental and human demand. A pattern of generally below-normal rainfall dates back to August 2023 at Wotje, and since this is one of the climatologically driest locations of the U.S. Affiliated Pacific Islands, deficits do not need to be large to begin stressing surface moisture needs. For August – mid-May, 35.9 inches of rain has fallen on Wotje (a rate below 3.8 inches per month), which is almost exactly 10 inches below normal. As a result, extreme drought (D3) persisted at Wotje this week.
Abundant to excessive rains fell on most other locations across the Marshalls, with the highest totals reported across the central tier of islands, including Ailinglapalap and Majuro. Almost 10 inches of rain fell on Ailinglapalap, and 7 inches drenched Majuro. Both of these locations recorded about twice the normal rainfall for the first two weeks of May. Both of these locations were experiencing some degree of dryness before the past week, and the excessive rains eased assessments by one category at both locations. Abnormal dryness (D0) was removed from Ailinglapalap, which now has no dryness designation, while Majuro was improved to D0 from its designation of moderate dryness last week. To both the north and the south of these locations, moderate rains fell. In the northwestern Marshalls, Kwajalein reported 3.8 inches of rain (2.4 inches of which fell in one day, May 11), bringing totals to 4.7 inches for the first two weeks of May (over 150 percent of normal). Earlier this calendar year, March was considerably wetter than normal, but April brought only about 2/3 of normal rainfall, and less than 42 percent of normal fell during both January and February (1.7 and 1.4 inches, respectively). Given these numbers, the drought designation at Kwajalein is not being changed this week (moderate drought, or D1), but the location is on the cusp of improvement. In the southwestern Marshalls, 3.7 inches of rain last week brought May totals to 4.9 inches at Jaluit, putting them on pace to received enough moisture to keep up with demand for the second successive month. However, the prior four months had been considerably drier than normal, and impactful dryness could redevelop fairly quickly.
In American Samoa, abundant May rainfall continued this past week in Pago Pago. Almost 16.7 inches of rain were reported for the first two weeks of May 2024, making this already the wettest May since 2017 and the second wettest since 2010 with over half the month to go. Since December 2023, just under 99 inches of rain has fallen on Pago Pago, and impactful dryness is unlikely for the foreseeable future.
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