Most precipitation across the contiguous United States fell in association with a large, impactful storm system that affected a broad area from the southernmost Rockies and the southern Plains eastward across a large part of the Mississippi and Ohio Valleys, the Southeast, and the Eastern Seaboard. Winter storm warnings at one point covered about one million square miles. Heavy to excessive amounts of snow, sleet, and freezing rain were widespread throughout the region. Numerous locations across Pennsylvania, New York, and New England recorded 1 to 2 feet of snow or snow and sleet. Elsewhere, totals reached as high as 17 inches in Ohio and West Virginia; 15 inches in Oklahoma, Missouri, Illinois, and Indiana; and 1 foot in Arkansas, Kentucky, Maryland, and Delaware. Intense sleet fell farther south, overlapping the southern sections of the heavy snow area. Sleet totals topped out near 7 inches in Arkansas, Louisiana, and North Carolina; near or slightly over 6 inches fell on scattered sites across Oklahoma, Texas, Louisiana, Mississippi, Tennessee, and Maryland; and localized amounts reached 4 inches in Texas, South Carolina, North Carolina, West Virginia, and Virginia. Freezing rain fell in abundance across portions of the South, and in some areas that experienced a changeover from sleet. States with at least one site reporting 1 inch thick ice accumulation included Oklahoma, Louisiana, Mississippi, Alabama, and South Carolina while peak amounts of 0.7 to 0.8 inch were reported in Texas, Kentucky, Tennessee, Georgia, Virginia, and West Virginia. Widespread power outages and tree damage was reported in many locations that received heavy freezing rain. Liquid-equivalent precipitation totals associated with this system exceeded an inch in parts of the southernmost Rockies, in a band from eastern Texas and western Arkansas eastward through Alabama, most of Tennessee and Kentucky, the central and northern Virginias, Maryland, Delaware, New Jersey, and in scattered locations across adjacent areas, including the Northeast. Scattered areas across the southern tier of the Lower-48 recorded over 3 inches of precipitation, including central Texas, southern Louisiana and adjacent Texas, and a fairly solid band from northeastern Texas through northern Louisiana, northern Mississippi, and northwestern Alabama. Up to 10 inches fell on one patch in southwestern Louisiana, and localized amounts exceeded 4 inches in northern Mississippi and a few other scattered areas.
However, despite the extensive coverage of impactful precipitation, the storm has not yet brought about broad areas of drought relief. Improvements were made where some of the heaviest liquid-equivalent precipitation fell, including a few places where it fell in frozen form. However, Arctic air has settled into the eastern states in the wake of the storm, and in many if not most areas, the water that could eventually help ease drought conditions was locked up in accumulated frozen precipitation, and can’t provide tangible improvements to drought impacts until it has melted. In the South, this may be only a matter of a few days, and relief was depicted more quickly there than farther north, especially in the northern tier of the East where temperatures may remain below freezing for extended periods of time.
Along the northwestern and southeastern edges of the winter storm, light to moderate precipitation was recorded, with totals ranging from a few tenths to nearly an inch over the western half of Texas and from much of Oklahoma northeastward through most of Missouri, Illinois, Michigan, Indiana, Ohio and the upper reaches of the Northeast. Similar amounts were noted to the south of the heaviest precipitation, generally across portions of the Carolinas, southeastern Georgia, Florida, and the immediate central Gulf Coast.
In other parts of the Lower-48, very little if any precipitation was recorded. The single widespread and extremely impactful winter storm was responsible for almost all of the precipitation observed this week.
Northeast
Liquid-equivalent precipitation totals ranged from 1 to locally 3 inches across the southern half of the Northeast Region, with amounts closer to 0.5 inch observed farther north. Isolated higher amounts were observed downwind from Lakes Erie and Ontario in association with lake-effect snow that fell as Arctic air rushed into the region behind the winter storm. Improvement was limited to a few small, isolated patches across the Northeast. Most areas were unchanged because the water that might help an area lacking in moisture was locked up in frozen precipitation sitting on but not melting into the ground. Despite the winter storm, many locations have only recorded one-half to two-thirds of normal precipitation over the last 60 days, with a few lesser amounts in parts of southwestern Pennsylvania and upper New England. Areas immediately downwind of the Great Lakes have been frequent recipients of Lake-effect snow, and 60-day precipitation amounts are closer to normal there.
The winter storm brought widespread moderate to heavy precipitation to large parts of the Southeast Region, with near or below normal totals restricted to Florida, portions of southern and eastern Georgia, and scattered areas across the Carolinas. One to several inches of precipitation was widespread across most of Alabama, western Georgia, and northern Virginia. Improvements were made across a few sections of Alabama, where precipitation outside the northern tier fell mostly in liquid form. But improvements were less common farther east, where totals were generally lower and more of the precipitation fell in frozen form. On the other hand, precipitation deficits continued to mount in areas that missed the bulk of the precipitation, specifically along the Tennessee/North Carolina border, in a few spots across southern and eastern Georgia, and especially across the Florida Peninsula, where the week was dry and moisture deficits increased. Large patches across the southern half of the Florida Peninsula and a few areas farther north have recorded less than one-quarter of normal precipitation during the last 90 days. D3 was introduced over part of the northern Florida Peninsula, and D2 was expanded into more of the southern and east-central Florida Peninsula.
One to several inches of precipitation was widespread across most of Tennessee, Mississippi, Louisiana, central and southern Arkansas, the eastern Texas. Improvements were introduced in a number of areas, generally the areas that received the most precipitation, where much of the precipitation fell in liquid form, or where drought was already waning. To wit, some relatively broad improvements were introduced in Tennessee and to a lesser extent Mississippi. Farther west, where subnormal precipitation dates back at least several months, improvements were more targeted to the areas receiving the heaviest precipitation, especially from central Louisiana northward where precipitation remained unmelted. Despite the precipitation accompanying the massive winter storm, Many areas in a band from northern Arkansas to the Louisiana Gulf Coast recorded 8 to 10 inches less than normal precipitation over the past 90 days, with a few spots in northeastern Arkansas and east-central Louisiana recording deficits approaching 12 inches during this period. Farther west, moderate to heavy precipitation was fairly widespread in eastern Texas, with lesser amounts toward the central part of the state. Southeastern Oklahoma reported amounts similar to eastern Texas (1.5 to locally 3.0 inches), but most areas farther northwest recorded less than an inch. With much of the precipitation remaining locked up in frozen form, only a few surgical improvements were introduced in the areas with the most extreme totals in eastern Texas. A few inches of liquid-equivalent precipitation also fell farther southwest over south-central Texas. Temperatures were above freezing there at the end of the period, and the environment was beginning to respond to the moisture infusion, so somewhat more aggressive improvements were introduced there.
The winter storm brought 1.5 to locally 3.0 inches of precipitation to most of Kentucky and some areas near the Ohio/Mississippi Rivers’ Confluence, but amounts were much less impressive farther north. The southern tiers of Illinois, Indiana, and Ohio received near or slightly over an inch of precipitation while central and southern Missouri and the central tiers of Illinois, Indiana, and Ohio recorded 0.5 to 1.0 inch. The western Lower Peninsula of Michigan also recorded 0.5 to 1.0 inch for the week, most of which resulted from lake-effect snows downwind from Lake Michigan. Meanwhile, parts of the eastern Lower Peninsula along with a swath from northern Missouri through northwestern Ohio were on the periphery of the storm and recorded only a few tenths of an inch. Across the Upper Peninsula of Michigan, Wisconsin, Minnesota, Iowa, and northwestern Illinois, little or no precipitation fell. Drought improvement was introduced in parts of Kentucky where dryness was already waning when the storm hit, and also in a part of southern Illinois and adjacent Missouri where over 1.5 inches fell. Elsewhere, bitterly cold conditions kept the ground frozen and squelched both human and environmental moisture demands, so drought remained unchanged across Missouri and most areas north of the Ohio River this week..
Most of the High Plains Region was dry last week, with a amounts of a few tenths to approaching one inch fell on much of central and eastern Kansas and on scattered higher elevations in Colorado and Wyoming. Otherwise, little or nothing fell. The Region – outside the higher elevations – is climatologically cold and dry, so precipitation deficits increase very slowly, and demand is lower this time of year. Dryness and drought was essentially unchanged in most of the High Plains Region, with some scattered deterioration introduced in parts of western Colorado (to D1 or D2). Drought intensification was also introduced around the Black Hills and adjacent western South Dakota (to D0 or D1), where snowpack is deficient and slowly declining.
West
The southern fringe of the West Region was impacted by the western edge of the winter storm, resulting in over 1.5 inches of precipitation across a few patches from southeastern Arizona across southern New Mexico. Amounts exceeded 3 inches in parts of south-central New Mexico north of the Texas Big Bend. The precipitation fell mostly in liquid form in southeastern Arizona, and was sufficient to bring improvements into that area. Farther east, although amounts were a little heavier, the precipitation was primarily in frozen form, and remained unmelted. Therefore, only a few targeted improvements were introduced in a few small areas reporting the highest precipitation amounts (over 3 inches). Elsewhere, most of the Region received no measurable precipitation, with just a few tenths falling on some of the higher elevations of the Rockies. Still, there was no tangible deterioration across the Region during the dry week, in part because it followed a few weeks of relatively abundant precipitation. As a result, the Drought Monitor depiction was unchanged outside parts of the southern fringes of Arizona and New Mexico.
Caribbean
Abnormal dryness (D0) remained unchanged from last week. Several locations, primarily in the northwestern and interior northeastern sections of the Commonwealth, reported 2-3 inches of rain. Broader across western, north-central, south-central and eastern parts of the island reported totals approaching or exceeding one inch. Most locations elsewhere reported at least a few tenths of an inch. About two dozen sites across Puerto Rico are reporting unusually low streamflows among the lowest 10 percent on record this time of year. These were in northwestern Lajas, southeastern Arecibo, northern Ponce, eastern Santa Isabel, northern Caguas, central Trujilo Alto, and a few miles south of San Juan.
The U.S. Virgin Islands received much-needed precipitation this week, but rainfall was not enough to improve conditions. CoCoRaHS stations situated across St. Croix recorded 0.58” – 1.24” of rain this week. Well water levels at Adventure 28 Well were at 19.33 ft. this week, which was 3.35 ft. lower compared to last week. CoCoRaHS stations on St. John recorded 0.54” – 1.63” of rain this week. Well water levels at Susannaberg DPW 3 well were at 12.76 ft. CoCoRaHS stations on St. Thomas Island recorded anywhere from 0.49” – 0.54” of rain this week. The Grade School 3 Well was at 7.6 ft this week, which was 0.4 ft higher compared to last week. St. Croix Island will remain under abnormal dryness, while St. John and St. Thomas Islands will remain in moderate drought.
The two areas of abnormal dryness (D0) – one in the northwestern Mainland, one in south-central - were both expanded to the west/southwest. The added area in northwestern Alaska was included because low and poor snow conditions are beginning to impact overland travel. Farther south, precipitation deficits have waxed and waned for a while, but 5 locations are reporting 6- to 12-month precipitation totals among the lowest 10 percent on record over part of the south-central Alaska D0 region (Alyeska, Grouse Creek Divide, Summit Creek, Indian Pass, and Middle Fork Bradley), with a couple ranking among the lowest 5 percent.
Precipitation amounts exceeded 3 inches on portions of Kauai and some of the southernmost reaches of the Big Island. Lesser amounts (a few tenths to locally near 1.8 inches) fell elsewhere. This kept Kauai free of any dryness, but essentially maintained dryness and drought designations elsewhere. There were a few small areas of deterioration introduced to better align with current low streamflows: Southeastern Oahu (to D1), northwestern Maui (to D3), and a small part of the northeastern Big Island (to D2). Precipitation deficits on varying time scales are scattered across the central and southeastern islands. Molokai reports 2.20 inches since mid-November, compared to a normal of 7.59 inches. At Honolulu, heavy precipitation (over 4.5 inches) fell December 13-20, but since then, only 1.43 inches of rain has fallen, whereas normal is about 2.5 inches.
Precipitation varied across each island of the Republic of the Marshall Islands (RMI). Islands like Ailingalapalap and Utirik received little rainfall, at 0.1” and 0.2”, respectively, this week. Though Utirik remains in moderate drought, Ailingalapalap remains free of drought and dryness. Another island under moderate drought, Wotje, received much-needed rain this week, at 0.92”. However, it was not enough to improve conditions. The islands of Jaluit and Mili received adequate rainfall this week, at 2.2” and 1.97”.
Like the RMI, the Federated States of Micronesia (FSM) has received varying amounts of rainfall. Pingelap received 0.2” of rain this week. With 0.71” of rain for the month of January, Pingelap will receive a 1-category degradation to moderate drought. Other islands that didn’t receive much rainfall include Yap, Lukunor, and Kapingamarangi, which received 0.2”, 0.32”, and 0.44” respectively. Kosrae and Woleai received adequate rainfall this week, having received 2.04” and 2.68”, respectively. The Republic of Palau experienced a drier week, with the Koror station receiving only 0.22” of rain and the WSO in Palau receiving 1.01” of rain.
A wet week was in store for the Marianas Islands. Guam received the least amount of rainfall, with only 1.66” of rain. Rota and Tinian, however, received 4.69” and 4.4” of rain, respectively, this week. The island of Saipan received the most rain this week, with the International Airport receiving 5.85” of rain, and the AMME NPS receiving 9.41” of rain. It is important to note that the Marianas Islands are in the dry season. American Samoa has also experienced a wet week. 5.89” of rain fell at the Pago Pago Airport this week. The Siufaga Ridge received 11” of rain, and the Toa Ridge received 9.07” of rain this week.
Looking Ahead
Not much precipitation is expected across the contiguous U.S. A strong but compact coastal low is expected to intensify rapidly off the Carolina coast. There is a great deal of uncertainty regarding the evolution of this system, exacerbated by the compact nature of the system, which means a small change in track could have big implications for precipitation amounts at any given location. The Carolinas and southern Virginia are the most likely regions to receive moderate to heavy precipitation, and given the much below normal temperatures in place, it will likely be mostly or entirely snow. Snow could affect a larger area surrounding this region, but odds for heavy snow drop moving away from the Carolinas and southern Virginia. Later, the strong low pressure system will head northeastward, possibly pushing moderate to heavy snow onto portions of the immediate Atlantic Coast from Maryland northward. In the areas most directly affected, amounts near or exceeding one inch (liquid equivalent) are expected, with several tenths of an inch possible a bit farther away from the storm. Moderate to heavy precipitation is also expected over the western half of Washington and adjacent Oregon. The Washington Cascades and far northwestern Washington are expecting 2.5 to 5.0 inches of precipitation, with totals ranging from near 1.0 to 2.5 inches in the rest of the area. Only light to locally moderate precipitation, if any is forecast elsewhere across the contiguous U.S. Several tenths to an inch may fall on northern Idaho, and a few tenths of an inch are forecast across some of the higher elevations of Wyoming and Colorado, parts of the northern Plains, and portions of the Florida Peninsula. Light amounts at best are expected elsewhere across most of the contiguous U.S. Meanwhile, the pattern featuring abnormally cold weather in the eastern half of the Lower-48 and unseasonably mild temperatures farther west. Subnormal temperatures are expected across a broad area from the central and southern Great Plains eastward and northeastward through the Eastern Seaboard outside northern New England. Temperatures are expected to average 10 or more degrees below normal in much of this area, with isolated sites in the Mid-Atlantic and southern Florida reaching 15 degrees below normal. Farther west, above-normal temperatures are expected to cover most areas from the High Plains to the West Coast. Temperatures are expected to average 10 to approaching 15 degrees above normal across the Great Basin, northern Intermountain West, and the central and northern sections of the Rockies and High Plains.
The 6- to 10-day outlook for February 3-7 depicts an eastward expansion of abnormal warmth into the middle of the Lower-48 while subnormal temperatures persist in most areas from the Lower Mississippi Valley, Lower Ohio Valley, and eastern Great Lakes to the Atlantic Coast, excepting northern New England. Odds for above-normal temperatures increase moving westward, with chances of at least 80 percent in place over parts of the northern High Plains and from the western Rockies to the Pacific Coast. Meanwhile, chances for subnormal temperatures top out above 70 percent across southern Florida, eastern North Carolina, and adjacent Virginia. Warm weather is favored across most of Alaska – especially southeastern sections – and throughout Hawaii. Wetter than normal conditions are also favored across the 49th and 50th states, but increased odds for surplus precipitation in the Lower-48 are limited to the southern Plains. Meanwhile, enhanced chances for subnormal precipitation covers the northern Plains and most areas from the Rockies to the Pacific Ocean. Chances for abnormal dryness exceed 60 percent across the Great Basin and the northern Intermountain West. Meanwhile, Chances for below-normal precipitation are slightly elevated along the Eastern Seaboard, though odds of 40 percent or higher are limited to a swath from central Florida through the eastern half of South Carolina.
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