Summary

January 21, 2021 – Unlike the previous week, most countries experienced a relatively dry week, with the significant exceptions of the Pacific Northwest and northern Intermountain West. Amounts greater than 1.5 inches are common, with parts of the Cascades and coastlines recording 4 to 8 inches of rainfall. Elsewhere, most of New England has moderate rainfall, with more than 1.5 inches falling over southern Maine and neighboring New Hampshire. Areas from the upper Midwest to the east through the Great Lakes Region and the lower Northeastern recorded 0.25 to 1.0 inches locally, but the rest of the country received little or no. But given the time of year, the dry week didn’t cause widespread damage. Most of the territory has not changed, and significant increases have been limited in the Pacific Northwest.

Northeast

Light to moderate rainfall has fallen in New England while little or nothing has been recorded further south. Most of the territory remains unchanged due to the lingering long-term moisture deficit, except in southern Maine, where 1.5 to 2.0 inches of rainfall is driving the removal of D0.

Southeast

Little or no rainfall falls in the area; however, the moisture deficit was not sufficient to produce wide-scale D0 conditions from Virginia to Georgia. Areas of abnormal drought still exist, with some expansion in central Florida and parts of western Georgia. Further east, a wider D0 area was introduced in Alabama due to a greater moisture deficit in adjacent parts of the Southern Territory. In the new region D0, rainfall has been 2 to 5 inches below normal for the past 60 days.

South

Little or no rainfall fell across the region, causing damage to several areas of southern and western Texas. The conditions D2 to D4 have taken root. Meanwhile, dry weather caused abnormal drought to emerge over large parts of Tennessee and much of Mississippi. Smaller areas developed in Arkansas and Louisiana. Since mid-October 2020, rainfall has been between 4 and 8 inches less than normal in swaths of northeast Louisiana through northwest Mississippi and western Tennessee.

Midwest

Most regions record light to moderate rainfall (0.25 to 1.0 inch locally), with little or no falling in the Ohio Valley, northwestern Minnesota, and Missouri. The dry week did not change the conditions enough to bring about any improvement, except for parts of southeastern Missouri adjacent to drought in the far south, and small areas in areas D2 through D3 were established in northwest Iowa.

Plateau

Similar to conditions in other regions, little or no rainfall was observed this week, outside of eastern North Dakota. Almost the entire territory has not changed compared to last week which has kept most of the territory intact. The exception is found in eastern North Dakota, where light rainfall is sufficient to reduce the extent of D2 conditions. Further west, small areas of damage were found in north-central Wyoming (to D1) and mid-west Dakota (deteriorating to D1-D2).

West

In stark contrast to the areas farther east and south, heavy rainfall was dropped in parts of the Pacific Northwest and parts of the northern Intermountain West. Most of the Idaho Panhandle and neighboring parts of Montana report heavy rainfall, with the highest altitude reaching 4 inches. Further west, heavy rainfall also wets the Cascades, and the Pacific Coast from Washington to south to northwest California. Most of this area – including the lower elevations between the Cascades and coastal areas – records at least 1.5 inches of rainfall while parts of the higher elevations are covered by 4 to 8 inches of rainfall locally. As a result, an improved patch was introduced, with D3 removed entirely from central Washington, and an unclear reduction in D0 to D3 coverage in Oregon and northwestern California. With most of the central and southern parts of the Western Territory already in D3 to D4, not much more damage could be done, but a few small areas damaged enough to be reflected on the map, particularly north-central Utah (up to D2), in northeastern Utah (to D4), and most southeastern New Mexico along the Mexican border (to D4).

Alaska, Hawaii and Puerto Rico

Heavy rains drove most of Hawaii at the end of the period. No fixes were introduced this week, allowing for impact assessments after the entire storm has cleared away. Meanwhile, the weather is not very good to keep the dry area unchanged.

Pacific Islands

Weather across the US Affiliated Pacific Islands (USAPI) during this USDM week (01/13 / 20-01 / 19/21) was dominated by persistent surface troughs in western Micronesia and the Inter-Tropical Convergence Zone (ITCZ). across eastern Micronesia which sometimes extends to western Micronesia. Other small surface Palau or trade-wind disruptions arise in the region, weak circulation develops near Palau and western Yap states, and trade-wind disruptions across northern RMI. Some faint disturbance crosses the Mariana Islands, but the weather there is predominantly dominated by dry wind exchange air masses. South of the equator, a weak trough moved across the Samoan Islands earlier in the week, but instead high pressure mountains dominate the weather.

Satellite-based 7-day rainfall forecasts (QPE) show a 2+ inch rainfall band across the States of Palau and Yap extending from about 2 degrees North latitude to 10 N in some places. The band stretches eastward along the ITCZ ​​across the rest of the Federated States of Micronesia (FSM) and the Marshall Islands (RMI) but narrows down, reaching from about 5 N to 8 N above the RMI. Within the band, a large 4+ inch area of ​​rain stretches across the entire length of the region, with a smaller amount (0.5 to 2.0 inches) extending to the equator at places in the west and central FSM. Little or no rainfall was analyzed in QPE across the Mariana Islands and Samoa.

Conditions have been relatively dry in the short term in American Samoa, although not to an abnormally dry level. Suifaga Ridge is receiving 1.12 inches of rainfall this week, Toa Ridge reporting 0.75 inches, and 0.67 inches dropping on Pago Pago.

In Palau, 2.39 inches of rain fell this week, and 1.97 inches fell on Koror, so drought-free conditions continue there.

The Federated States of Micronesia have remained largely drought or drought free this week, with the significant exception of Kapingamarangi. At least 2.04 inches of rain fell this week in Yap after 4.08 inches there last week. Ulithi received 4.09 inches of rainfall this week. Woleai received just 0.36 inches this week, marking the third consecutive week below their weekly minimum, even though his condition hasn’t quite degenerated into an abnormal drought. Fananu has only received 0.26 inches of rainfall this week, but conditions here haven’t descended into an abnormal drought, as it fell 4.88 inches last week and dropped 10.17 inches three weeks ago. Chuuk is experiencing 3.89 inches of rainfall this week, so normal conditions have continued there. Normal conditions also continued at Lukunoch, where it fell 3.20 inches. Nukuoro experienced 3.59 inches of rainfall this week, following 8.51 inches last week, so wet conditions have continued. Extraordinary short and long term drought continues in Kapingamarangi despite 2.30 inches of rain this week. This marks the first week since early December that the weekly minimum has been reached, and no monthly minimum rainfall has been achieved there since April 2020. Pohnpei’s wet conditions continue this week with 3.81 inches of rainfall. In Pingelap, 0.83 inches of rainfall occurs for a drier week, but the minimum January rainfall has been met, and the December 2020 rainfall is at the 97th percentile, so conditions here remain wet. Another rainy week hits Kosrae, as last week it was 12.40 inches of rain followed by another 6.53 inches.

Short-term abnormal drought developed in Saipan, where rainfall hit 0.48, 0.33 and 0.07 inches at three different measuring locations this week. This is the sixth consecutive week that rainfall falls below its weekly minimum. Rota is receiving only 0.21 inches of rainfall this week, bringing it below the weekly minimum for the fifth time in the last six weeks. However, the last week of December saw 4.04 inches of rain, so conditions haven’t eased into short term abnormal drought in Rota. Only 0.48 inches of rainfall has accumulated on Guam this week, the fifth consecutive week below their weekly minimum, though conditions haven’t eased enough to be an abnormal drought.

The Marshall Islands remain drought-free this week, despite short-term abnormal drought in Kwajalein and Wotje. In Kwajalein, 1.48 inches of rainfall is falling this week, marking the 7th consecutive week of minimum weekly rainfall there. By 4.02 inches, December also missed its monthly minimum, so the short-term abnormal drought continues. In Wotje, short-term abnormal drought continues, as 0.95 inch rainfall this week is the first measured rainfall for 2021. Data from Utirik this week is not available, so no drought figures have been generated there. In Jaluit, 0.67 inches of rainfall this week followed 3.23 inches last week, so normal conditions continue there. Majuro received 3.15 inches of rainfall for the second week in a row and remains drought-free this week. Mili remains drought free as 4.27 inches of rainfall fell this week.

Virgin Islands

Minimal rainfall this week throughout the US Virgin Islands; 0.26 inch falls on St. John, 0.09 inches in St. Croix, and 0.21 inches in St. Thomas. At St. Croix, short and long term rainfall deficit still supports short and long term abnormal drought. At St. John and St. Thomas, short-term rainfall deficits continue to support short-term abnormal drought.

Looking ahead

The most significant weather for the next 5 days (21-26 January 2021) will be heavy rainfall that extends across the Southeast. Between 1.5 and 4.0 inches is estimated from east Texas through southern Alabama and northern Georgia. Light to moderate amounts should dampen the rest of the Southeast. Further west, from the central and southern Rocky Mountains to the California Coast, significant rainfall will fall at higher altitudes. Most mountains expect 1 to 3 inches. The rest of the Southwest and Pacific Northwest is expecting 0.5 to 2.5 inches. Elsewhere, up to 0.5 inches of light to moderate rainfall is expected for the upper Midwest, and little is expected over the Northeast, High Plains, and the rest of the Midwest and Great Pains.

The prospect of an extended CPC range of 6-10 days (27-31 January 2021) supports surplus rainfall from the Rockies to the West Coast, much of the Midwest, and parts of the Southeast interior. Most of Alaska also expects above-normal rainfall. Meanwhile, rainfall is likely below normal throughout Florida, in the Northeastern Valley and Ohio, the Southern Plains, and eastern Montana. Meanwhile, cooler than usual weather is anticipated in the Northeast, central Atlantic State, and large areas from the Rockies to the West Coast. In contrast, the increased odds for above-normal temperatures cover roughly the southeast quarter of the country