January 16, 2024 National Drought Summary

The discussion in the Looking Ahead section is simply a description of what the official national guidance from the National Weather Service (NWS) National Centers for Environmental Prediction is depicting for current areas of dryness and drought. The NWS forecast products utilizedinclude the HPC 5-day QPF and 5-day Mean Temperature progs, the 6-10 Day Outlooks of Temperature and Precipitation Probability, and the 8-14Day Outlooks of Temperature and Precipitation Probability, valid as of late Wednesday afternoon of the USDM release week. The NWS forecast webpage used for this section is: http://www.cpc.ncep.noaa.gov/products/forecasts/.

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A nearby front brought periods of clouds and scattered showers to the USVI this past drought week (Wed, Jan 10 – Tue, Jan 16, 2024), with maximum rainfall accumulation just over one inch. Mid to upper-level high pressure and drier air prevented the development of deep convection/widespread thundershower activity during the week. Breezy conditions ensued later in the period as building surface high pressure over the western Atlantic strengthened the pressure gradient over the northeastern Caribbean.

Satellite-based Quantitative Precipitation Estimates (QPE) from SPoRT IMERG imagery depicted rainfall amounts less than 0.75-inch during the week ending January 16th, though several rain gauges recorded locally greater amounts.

Rain gauge measurements across St. Croix this week ranged from 0.10-inch at station VI-SC-24 (Christiansted 2.1 ENE) to 0.76-inch at VI-SC-34 (Frederiksted 1.9 NE). Intermediate rainfall amounts included 0.18-inch at VI-SC-20 (Frederiksted 1.7 ESE), 0.22-inch at East Hill, 0.32-inch at VI-SC-23 (Christiansted 6.5 W), 0.37-inch at VI-SC-30 (Christiansted 1.7 SW), 0.45-inch at VI-SC-10 (Christiansted 1.6 E), 0.46-inch at VI-SC-29 (Frederiksted 2.5 NNE), and 0.75-inch at VI-SC-35 (Frederiksted 1.3 ENE). At the Adventure 28 Well, groundwater levels ranged from 32.84 feet (Jan 10, midnight) to 33.01 feet (Jan 16, 8am AST), a net fall of -0.17 feet. St. Croix’s drought depiction remains unchanged this week at D1(SL).

St. John received considerable precipitation this week, with 1.04 inches measured at VI-SJ-3 (Windswept Beach), 1.00 inch at VI-SJ-5 (Cruz Bay 1.6 E), and 0.76-inch of rain at VI-SJ-4 (Cruz Bay 0.8 NE). The groundwater level at the Susannaberg DPW-3 Well fell slightly this week by -0.32 feet. Drought-free conditions persist at St. John this week.

Weekly rainfall accumulations on St. Thomas ranged from 0.39-inch at VI-ST-5 (Charlotte Amalie West 4.2 WNW) to 0.83-inch at VI-ST-14 (Nadir 0.3E, Tropical Marine). Intermediate rainfall amounts included 0.52-inch at VI-ST-1 (Anna’s Retreat 2.5 ESE), 0.74-inch at VI-ST-15 (Charlotte Amalie West 1.3 N), and 0.79-inch of rain at VI-ST-13 (Charlotte Amalie 1.2 NNW). The Grade School 3 Well reported a water level of 10.62 feet (Jan 10, midnight) which rose +1.36 feet to 9.26 feet below the land surface (Jan 16, 8am AST). The drought depiction at St. Thomas remains unchanged this week at D2(L).

As this is early in the dry season for the northeastern Caribbean basin, there are no compelling reasons to change the drought depictions this week at any of the Islands.

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During this past drought week (Wed, Jan 10 – Tue, Jan 16, 2024) over the South Pacific, a surface trough and associated area of wind convergence located south and west of American Samoa brought periods of heavy rainfall and isolated thunderstorms to the islands/atolls. North of the equator, a dry trade-wind regime dominated most of the USAPI region, with the more significant rainfall (at least 1-inch) remaining south of about 6 deg N and also over the Republic of Palau. Patchy showers were reported in the vicinity of the Marianas associated with shear lines. Strong storm systems moving over the Northwest Pacific resulted in enhanced pressure gradients and stronger winds for much of the USAPI region late in the drought week. With increasingly dry conditions occurring over much of the region, any periods of strong winds are expected to increase the risk of fire danger.

Satellite-based Quantitative Precipitation Estimates (QPE) from SPoRT IMERG imagery for the past 7-days depict rainfall amounts generally under 0.75-inch over much of the USAPI region. The exceptions included southern Micronesia and the Republic of Palau (generally 2-4 inches). Over the South Pacific, rainfall accumulations ranged from 4-8 inches over the vicinity of American Samoa.

Each of the three reporting sites on American Samoa exceeded the minimum monthly precipitation to meet most water needs (4 inches) during this past week. These stations include Pago Pago (8.06 inches of rain), Siufaga Ridge (6.59 inches), and Toa Ridge (6.00 inches). This is 6-8 times the minimum weekly water threshold of 1 inch, and in the case of Pago Pago twice the monthly minimum of 4 inches. Given such heavy precipitation amounts this week, and a whopping 25 inches in December, Tutuila remains free of any dryness or drought.

The Republic of Palau continues to enjoy drought-free conditions. The Palau International Airport (Airai) received 3.62 inches of rain (1 day missing) this week, and the Koror COOP measured 2.57 inches of rain (1 day missing). Both of these rainfall totals comfortably surpassed the 2-inch weekly minimum water requirement.

Rainfall amounts recorded across the Commonwealth of the Northern Mariana Islands (CNMI) this week ranged from 0.22-inch at Guam to 1.00 inch at both Rota and the Saipan ASOS site. Additional rainfall observations include 0.85-inch at Tinian, 0.61-inch at the Saipan International Airport manual gauge, 0.41-inch at Dededo, and 0.36-inch of precipitation at Agat. Despite late gains in rainfall this week at several stations, in which the weekly minimum water requirement of 1 inch was barely met, the CNMI depictions were all degraded to D0(S).

Some of the driest conditions in recent weeks have occurred across the Republic of the Marshall Islands (RMI). Ailinglaplap measured the most rain this week, a mere 0.20-inch (1 day missing), followed by Majuro (0.11-inch of rain) and Kwajalein (0.05-inch). Majuro and Kwajalein have now experienced 4 consecutive dry weeks, and their drought designations were accordingly degraded to D0(S). The Majuro reservoir level is near 29.5 million gallons, about 82% of capacity. Kwajalein has reported browning of grass and some vegetation yellowing at this time. Jaluit, Mili, and Wotje all reported zero precipitation this week (1-day missing), and the first two stations have now had 4 consecutive dry weeks triggering degradation of their drought depictions to D0(S). Lack of available data at Utirik precluded analysis this week.

With several exceptions, the Federated States of Micronesia (FSM) received well under an inch of rain this past drought week. These exceptions included Kapingamarangi (6.25 inches of rain, 1 day missing), Nukuoro (5.92 inches of rain, 1 day missing), Kosrae (2.12 inches, 2 days missing), and Lukunoch (1.34 inches, 2 days missing). With the exception of Lukunoch, each of these stations surpassed their 2-inch weekly minimum rainfall required to meet most water needs. Despite reaching its weekly minimum water requirement of 2 inches, Kosrae’s designation was degraded to D0(S) based on rainfall and satellite information during the past few weeks. For the majority of FSM stations, conditions are rapidly declining and a number of impacts are already being felt. In Pohnpei, 0.20-inch of precipitation (1 day missing) was noted this week, making this the 5th consecutive dry week. Effective January 12th, a State of Emergency was declared by the governor for Pohnpei State for ongoing drought and response efforts. In Kolonia, coastal town and capital of Pohnpei, water shortages were reported at some hotels, hospitals, and restaurants, as well as a significant fire at a local dump site. Pohnpei’s drought designation was degraded from D0(S) to D1(S) this week. At Yap, 0.83-inch of rain (2 days missing) was measured, marking the 8th consecutive dry week. Water shortages are being reported at some of the outer atolls (Ifaluk, Elato, and Lamotrek), where the lack of rain during the past few weeks prevented the refilling of water tanks. Potable water is being shipped to those areas. Yap’s designation was degraded from D1(S) to D2(S) this week. Woleai and Chuuk received 0.35-inch of rain and 0.18-inch of rain this week, respectively (2 days missing), and the last 4-5 weeks have been dry. The drought designations at both stations were degraded to D0(S). Other precipitation totals measured this week included North Fanif (0.29-inch), Ulithi (0.17-inch, 1 day missing), Pingelap (0.12-inch, 1 day missing), and Rumung (0.04-inch, 3 days missing). No analysis was possible this week at Fananu due to missing data.

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