The Mariana Islands, particularly the Commonwealth of the Northern Mariana Islands, have been anchored in a very dry trade-wind pattern for several months now.
As assessed by the U.S. Drought Monitor team, Saipan`s International Airport has had the driest January through May on record.
Weak disturbances have provided showers for Guam recently, with above normal rainfall occurring during the month of May 2020.
During the past couple of weeks there has been a slight northward shift in convergent trade flow while upper-level divergence has strengthened across the region. The Inter-Tropical Convergence Zone and embedded disturbances have led to periods of showery weather across the region south of 14 degrees north recently.
This northward shift has brought some drought relief to islands of the northern Marshalls, Yap state, northern Chuuk state and Guam in the Marianas.
Showers have started to creep northward across Rota but Tinian and Saipan have remained extremely dry.
There are some indications that showers will continue to lift northward, bringing some relief to Tinian and Saipan in the coming weeks.
A wet trade-wind pattern continues to provide steady showers to islands between 4 degrees north and 8 degrees north across Micronesia.
Showers are gradually returning to islands near 10 degrees north with the northward shift in low-level convergence and the seasonal return of the tropical upper-tropospheric trough (TUTT).
This has led to some improvement to the drought situation across Yap, the northern islands of Chuuk state and the northern Marshalls near 9 degrees north.
Some recent rainfall (inches) from across the region:
Jan-Apr May May Jun Jun
Norm(%) Norm(%) 1-11 1-11(%)
Guam airport 102 8.16 190 2.13 90
Rota airport 61 2.62 65 1.49 86
Tinian airport 63 1.36 40 0.53 29
Saipan airport 59 1.10 40 1.01 61
WSO Majuro 113 15.78 160 2.12 58
Wotje 110 5.50 112 1.24 66
Utirik 123 M* M M M
Kwajalein/Ebeye 99 6.15 93 1.47 56
Ailinglapalap 89 11.65 108 4.23 116
Jaluit 88 13.80 127 1.68 49