This week was cooler than normal for Alaska and wetter than normal across the panhandle but drier than normal for the rest of the state. No change was made to the depiction, with only a small area of D0 remaining in the east-central region near Yukon Flats.

Trade-wind showers have been benefitting windward slopes across Hawaii, but they haven’t been enough to improve drought conditions although stream levels have improved. The showers haven’t been getting to the leeward areas, where vegetation continues to be stressed and producer reports indicate very poor pasture conditions. Moderate drought (D1) expanded on Kauai and the Big Island, severe drought (D2) was added to Kauai and Oahu, and D2 expanded on the Big Island.

The islands stretching across (west to east) Palau, The Mariana Islands, Micronesia, and the Marshall Islands are free of drought (D1 or worse), and D0 (abnormally dry) conditions are restricted to central and northern sections of the Marshall Islands. Meanwhile, moderate drought (D1) persisted at Tutuila on Pago Pago – this is the only location in the U. S. Affiliated Pacific Islands experiencing drought (D1 or worse). The only change in classification from last week occurred on Pingelap, where moderate to heavy rains ended abnormally dry (D0) conditions.

Despite some missing data, September 1 – 26 adds up to over 10 inches of rain at Koror. Anywhere from 13.4 to 26.9 inches of rain fell during each of the prior 4 months, making 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.

It was a wet week on the southernmost island of Guam in the Marianas, with 3.8 to 4.2 inches falling. Islands to the north received considerably less precipitation, as Rota, Tinian, and Saipan measured only 0.8 to 1.2 inches September 20 – 26. Normal weekly amounts at this time of year range from about 2.4 inches of rain on the northernmost inhabited islands to 3.3 inches in parts of Guam Island. Rainfall totals in September have been unremarkable, with Saipan recording somewhat above normal rainfall and most other sites receiving 70 to 90 percent of normal. All sites report over 8 inches for the month, which is enough to meet up with water loss and usage each month. This follows abundant August rainfall of 18 to 19.5 inches at most sites. As a result, there are no concerns about dryness for the time being, nor are any expected for the foreseeable future.

In general, rainfall totals increased from west to east across the islands of Micronesia last week. Amounts ranged from near or slightly under 2 inches in western locations like Yap and Ulithi, to between 4.4 and 5.3 inches in central locations like Lukunor and Chuuk Lagoon, to over 6 inches in eastern areas like Pingelap and Kosrae. A few spots on the northern tier of islands were slightly drier outliers (Fananu received about 2 inches of rain), and in southernmost sections of Micronesia, a slightly wetter than normal week at Kapingamarangi (2.3 inches of rain) added to an already-soaking September. Month-to-date totals are now just shy of 23.5 inches there, making September 2023 the wettest month at Kapingamarangi since June 2019 (23.68 inches) with four days to go. Elsewhere, September totals range from considerably below normal at Ulithi and Yap in the West (40 to 60 percent of normal, although a few days are missing) to near normal in central Micronesia, to somewhat wet (near 130 percent of normal) in Nukuoro and Pohnpei. The exceptional amount reported at Kapingamarangi is almost 3 times normal for September.

Last week, there were no drought designations anywhere in Micronesia, and the only site with any notable dryness was Pingelap (D0). Rainfall there, however, has increased since early September. The 3.65 inches reported last week pushes the September 1 – 26 total to 12.1 inches, which is about normal and well over the amount needed to keep up with demand. This has prompted the removal of D0 from Pingelap, and all monitored sites in Micronesia are now free of any drought or abnormal dryness. There is no immediate concern brought about by the subnormal September rainfall in western sections of the Nation – nost notably Yap and Ulithi – since exceedingly heavy rains (44 to 47 inches) fell the prior two months.

Unlike areas farther west, three of the six monitored locations were experiencing abnormal dryness (D0) last week (Kwajalein, Ailinglapalap, and Wotje), and these three locations remain in abnormal dryness this week. Weekly rainfall totals increased from north to south during September 20 – 26, with about 2.75 inches falling on Jaluit and Mili in the South, near-normal totals of 1 to 1.4 inches reported in Ailinglapalap and Majuro, and subnormal amounts of rain in Kwajalein (0.74 inch) and Wotje (no rain). These rains were insufficient to provide any relief in abnormally dry areas but were enough to stave off any deterioration into drought. With 4 days left in September, the month has brought much wetter than normal weather to Mili (16.8 inches, or 185 percent of normal) and typical rainfall totals to Jaluit (9.1 inches, or 90 percent of normal). Other areas have not seen as much rain, with Kwajalein receiving 6.4 inches (70 percent of normal) while Ailinglapalap, Majuro, and Wotje accumulated only 3.7 to 4.8 inches (43 to 55 percent of normal). September will be the second or third consecutive month with subnormal rainfall at these drier locales, And the third consecutive month short of the 8 inches needed to keep the moisture budget from declining. Conditions in the D0 sites are similar, but Kwajalein is a little drier than the others, at least mathematically. For July-September, 18.7 inches of rain has fallen there, which is more than 11 inches below (63 percent of) normal. But to date, no significant impacts have been reported due to the dryness, so the designation remains D0.

Following a few exceptionally wet days in early September, a pattern of below normal rainfall returned to Pago Pago after the first week of September. 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 6.77 inches dousing the region September 6 – 7. But these rains did not herald a lasting pattern change. A little less than 3.1 inches fell during September 8 – 26 when close to 5 inches would be expected. Due to meager rains earlier in the austral winter, reports of continuing vegetative stress, and a return to subnormal rains since the early-September downpours, moderate drought (D1) remains in place this week.

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