Beneficial rain fell in Alaska this week, eliminating D0 areas in the east and panhandle. Only a small area of D0 remained in the east central region near Yukon Flats.
Hawaii was mostly drier than normal this week, but no change was made to the depiction.
Along the chain of islands stretching across (west to east) Palau, The Mariana Islands, Micronesia, and the Marshall Islands, central and western sections are free from any notable dryness, but several locations from eastern Micronesia across the Marshall Islands are abnormally dry (D0). This includes two locations newly sliding into D0 this week (Kwajalein an Ailinglapalap). Well to the south, Tutuila on American Samoa remains in moderate drought (D1) despite a few very wet days in early September. This is the only drought noted among the U. S. Affiliated Pacific Islands.
Several days of reports are missing from Koror, but the dozen or so days of reports through September 19 add up to almost 9 inches for the month to date. With anywhere from 13.4 to 26.9 inches of rain during each of the prior 4 months, the Republic is free of any impacts from dryness, and the past few months of heavy rain will probably keep any problems at bay even if conditions dry out during the next couple of months.
Across the Marianas, the first 19 days of September have been a little drier than normal at Guam and Rota, where totals are under 7 inches for the months so far. Saipan has received over 9 inches of rain and is above normal for the month. During August, the three aforementioned locations recorded anywhere from 18.2 to 19.5 inches of rain, squelching any potential concerns about dryness for the time being.
Similar to the Marianas, most locations across Micronesia are drier than normal for September 1-19. Five sites (Yap, Kosrae, Lukunor, Pingelap, and Rumung) recorded 52 to 73 percent of normal for this period (generally 2.4 to 5.0 inches of rain, except 7.15 inches at Kosrae. But from June through August, rainfall was abundant across almost all of Micronesia, with anywhere from 10 to 31 inches reported at every location each month. Exceptions included a dry June and July at Fananu (12.28 inches, below the optimal amount of 8 inches both months), but a wet August there eased any developing concerns due to dryness. In addition, August was dry at Pingelap. About 80 percent of normal fell there during July, which was well above the amount needed to keep up with water usage. But August brought only 54 percent of normal rainfall (7 inches, below the optimum amount), and so far in September, 56 percent of normal (5 inches) has been reported. At that rate, September would also produce less rainfall than is generally needed to keep up with demand, although only by a few tenths of an inch. The subnormal rainfall for roughly the past 3.5 months, and with rain falling at a rate short of the preferred 8 inches per month during August 1 – September 19, abnormal dryness (D0) persists at Pingelap. Farther south, Kapingamarangi has endured several periods of significant drought over the past few years but concerns about recurring drought have been alleviated for the time being. Through September 19, year-to-date rainfall totaled 141.83 inches, far exceeding the normal of 98.48 inches. This is the wettest 9-month period since just over 148 inches fell March – November 2019. In contrast, the driest such period was May 2020 – January 2021, when less than 33 inches fell. As a result, resurgent drought should not be a concern for the foreseeable future.
September is off to a dry start in most of the Marshalls. Over 13 inches of rain has fallen on Mili, but other locations report only 2.7 to 5.4 inches. Wotje reports 3.3 inches during this period, which is about two-thirds normal and on pace for well under the 8 inches needed to ensure rainfall is keeping up with water demand. Rainfall was closer to normal in August, but as Wotje is climatologically one of the driest locations across the Pacific Ocean, monthly totals were considerably below the preferred total of 8 inches. Above-normal rain fell during the prior few months, but totals were considerably less than most other sites due to the relatively dry climatology. Considering all these factors, Wotje remains abnormally dry (D0) as it was last week. Subnormal precipitation has also been observed in the western Marshalls at Kwajalein and Ailinglapalap. At Kwajalein, less than half of normal rainfall was recorded in July 2023 while both August and September-to-date report 70 to 76 percent of normal. All three months brought less than 8 inches to Kwajalein, although August was just slightly less. With only 4.88 inches of rain this month so far, enough of a rainfall deficit has accumulated to justify a classification of abnormally dry (D0) being introduced this week. Ailinglapalap has been wetter than that during the same period, but somewhat below-normal July and August rainfall has been followed by a September with only 2.76 inches of rain (41 percent of normal) during the first 19 days. These conditions – especially the short-term lack of rainfall – justify also introducing D0 at Ailinglapalap this week. Across the eastern Marshalls, Mili has been considerably wetter than most of the Nation during the past several months, and while only 3.17 inches of rain has fallen on Majuro so far this September, August totals of over 11 inches were sufficient to squelch any concerns about abnormal dryness for the time being.
Rainfall reported from Jaluit has been low enough for over a year to justify introducing D0 this week, but there are concerns that the location has had a dry bias during this period, with reports generally lower than the actual amount that fell. Reports indicate that below normal rain fell for 17 of the 19 months since May 2022, including 10 months with 75 percent of normal or less reported. This equates to monthly totals below the optimum amount of 8 inches for 11 of those months. These statistics easily justify introducing D0 but concerns about the accuracy of the data prompted setting Jaluit’s official classification to “no data” this week. We are investigating the potential error and hope to rectify the situation soon.
Following a few exceptionally wet days in early September, a pattern of below normal rainfall returned to Pago Pago last week. The Austral winter (June – August 2023) is a dry time of year in the territory, with normal rainfall of 18.63 inches. This year, however, only 13.71 inches fell, with a meager 2.26 inches observed in August (36 percent of normal). Early September brought a few days of very heavy rain to Pago Pago, with 7.87 inches reported September 6-12 – more than any full month since May 2023. Somewhat drier than normal conditions returned this past week, with 1.61 inches reported. Summing September 1-19, more than twice the normal amount of rain has fallen. But with drier than normal conditions prevailing during the summer, the scant amount of rain recorded during August, and reports of vegetative stress continuing in parts of Pago Pago despite the soaking rains earlier in September, moderate drought (D1) remains in place this week.
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