This Week's Drought Summary (10/23)

Recently, precipitation has been spatially variable across the Contiguous U.S. (“Lower-48”). Over the past 30 days, heavy precipitation (4 to locally over 8 inches) fell on parts of central and southern New England, the interior Northeast (especially eastern New York state), the Ohio Valley (particularly northern Kentucky and adjacent areas), eastern South Carolina, eastern Florida, parts of the Tennessee and adjacent Mississippi Valleys, isolated sites in the central Plains, the higher elevations in the Rockies, central Arizona and other scattered locations across the Southwest, parts of the Great Basin, portions of California (where such amounts are unusual this early in the wet season), and the Pacific Northwest (where these amounts are not unusual).

In stark contrast, an inch or less of precipitation has been noted in the desert Southwest and lower elevations across the interior West, most of the central and southern Plains, the northern Great Plains, the northwestern Great Lakes, portions or northern and western Florida, and some interior sections of the Southeast and Mid-Atlantic region.

Given the regional variability, there were a lot of changes in the Drought Monitor this week, with large parts of the West, much of the Ohio and middle Mississippi Valleys, and scattered locations across northern Mississippi, the Eastern Great Lakes, and the Northeast. At the same time, conditions have deteriorated across much of the southern and south-central Plains, the South Atlantic region from interior Georgia through eastern Virginia, southern parts of the Lower Mississippi Valley, and scattered areas across the rest of the Southeast, the Mid-Atlantic region, the Northeast, the Upper Mississippi Valley, and the northern Plains.

In sum, the array of improvements and deterioration incorporated into this week’s Drought Monitor resulted in slight declines in overall coverage of the various drought severity levels across the Lower-48. Abnormally dry or worse conditions cover 72 percent of the country, down from 74 percent last week. About 21 percent of the country is experiencing Severe Drought or worse (D2-D4), down slightly from 23 percent last week. For the 50 states plus Puerto Rico in total, coverage of abnormally dry or worse conditions fell from 62 to just under 60.5 percent.

Northeast

The coverage of some degree of dryness (D0 or higher) declined very slightly but continues to affect a vast majority of the region (93 percent, down one percent). However, the extent of more intense drought (D2-D4) increased slightly from just under 34 to just over 36 percent. Compared to other Regions, changes were less widespread, with small areas of improvement noted in the western half of West Virginia, central and western Pennsylvania, eastern New York, and the central and western sections of New England. Meanwhile, dryness and drought coverage and intensity increased in a few areas from central Maryland northward through north-central New York, and across northern Maine. Precipitation totaled 1 to 3.5 inches across much of northern West Virginia, western Pennsylvania, western New York, and central New England. Other locations reported less, with little or none from lower New York state and southwestern New England southward through Delaware and eastern Maryland. The most widespread area of Severe to Extreme Drought (D2-D3) persisted across Maine and northern New England, with smaller areas of similar intensity were noted across eastern West Virginia and vicinity.

Southeast

A dry week resulted in significant areas of deterioration from eastern Virginia through sections of North Carolina, the central tiers of South Carolina and central Georgia, and scattered locations over the rest of the Carolinas, northern Georgia, and scattered areas from central Alabama through western Peninsular Florida. Sections of southern and northern Alabama along with sections of the western Florida Panhandle and northern Peninsular Florida reported more than a few tenths of an inch, and other areas were drier. Some locations near the central Gulf Coast and west-central Alabama received 1 to 2 inches, and a few patches of improvement were limited to parts of these areas. The dry week allowed coverage of dryness and drought to increase from 81 to 85 percent. Moderate drought or worse (D1-D4) expanded from less than 49 percent to over 58 percent of the Southeast Region, and coverage of severe drought or worse (D2-D4) is approaching 20 percent. The worst dryness in the region (D3) covered west-central Alabama, a new area in northwestern Georgia, and parts of the northern Florida Panhandle and adjacent areas of Georgia.

South

Moderate to heavy rain resulted in several areas of improvement in Tennessee, central and northern Mississippi, northeastern Louisiana, and eastern Oklahoma. Farther south and west, subnormal precipitation continued for another week, resulting in numerous areas of deterioration from central and southern Louisiana westward across Texas and central through western Oklahoma. The proportion of the Region experiencing some degree of dryness or drought (D0+) increased slightly this week, from 79 percent to about 80.5 percent. There was a bigger jump in areas covered by some degree of drought (37 percent, up from a bit over 32 percent). The most intense drought (D3 with some isolated patches of D4) cover parts of the panhandle of western Texas and a sizeable part of south-central Texas. The heaviest rains this week (2 to 4 inches) were observed in a broken pattern from northwestern Louisiana through northern Mississippi. In contrast, southern sections of the Lower Mississippi Valley and the vast majority of Texas and Oklahoma received a few tenths of an inch at best, with most sites reporting no measurable precipitation.

Midwest

Once again this week, many parts of the Midwest Region received moderate to heavy precipitation. There was some expansion of dryness and moderate drought from northern Minnesota through Iowa, where less precipitation fell, but much broader areas of improvement were noted over the Michigan Lower Peninsula and the Ohio Valley States. Overall, the extent of any degree of dryness or drought (D0-D4) dropped only slightly by 1 percent (to 71 percent), but there was a more substantial decrease in the coverage of the most intense categories. Severe drought or worse (D2-D4) covered over 14.5 percent of the Region on October 14, but less than 10 percent this week. The worst conditions in the Region (D3) stretched across parts of southwestern Missouri, east-central Illinois, central and northeastern Indiana, and northwestern Ohio. Between 2 and 4 inches of precipitation fell on a band from east-central Missouri across upper southern Illinois and into west-central Indiana, while 1.5 to 3.0 soaked a large part of the Michigan Lower Peninsula.

High Plains

A wide range of precipitation totals were observed last week. Generally, 1.5 to 3.0 inches hit the northern and western Dakotas, much of central and eastern Wyoming, and scattered locations in northwestern Wyoming. An inch or a little more fell on many locations in a swath from central Nebraska into southeastern South Dakota, but other locations reported several tenths of an inch of precipitation at best, with most areas from southwestern Wyoming through western Nebraska and from eastern Nebraska through Kansas reporting little or none. This pattern resulted in less change here than in most other regions. Areas of deterioration were introduced in parts of the east-central and southeastern High Plains Region while improvement resulted from heavier precipitation farther west. The most widespread areas of improvement covered southwestern Colorado and western Wyoming. Coverage of dryness and drought is considerably lower in this region than in others, with the total area entrenched in some degree of dryness or drought (D0-D4) dropping slightly to a bit over 36 percent this week. The extent of Extreme Drought (D3) was almost cut in half, from 3.3 percent down to 1.7 percent. There is no D4 in the Region, but D3 remains across much of southwestern Wyoming and part of central Colorado. The proportion of the Great Plains States in this Region experiencing some degree of dryness or drought (D0-D4) is relatively low compared to much of the Lower-48; specifically, 3 percent of North Dakota, 32 percent of South Dakota, 35 percent of Nebraska, and 28 percent of Kansas.

West

Some unusually heavy early-season rain and snow has affected portions of the West, including areas of central and southern California where October so far has been wetter than most such months on record. Large portions of central and upper southern California, the Great Basin, and the western and eastern tiers of Utah saw improvement on this week’s Drought Monitor, along with patches of central and eastern Arizona, southwestern Oregon, central and eastern Washington, and parts of eastern, southern, and western Montana. Only a portion of north-central Montana saw any deterioration. The total area covered by any dryness (D0-D4) declined from 80 to a bit over 74 percent this week while the coverage of the more intense drought categories (D2-D4) dropped from 38.5 percent to just over one-third of the Region. D3-D4 was still entrenched over a decent proportion of the Region, but declined from almost 9 percent last week to about 6.5 percent this week. The only remaining area of the most intense category (D4) is in north-central Idaho.

Alaska, Hawaii, and Puerto Rico

In Puerto Rico, abnormal dryness (D0) expanded through a few more municipalities in southeastern parts of the Commonwealth, consistent with continued subnormal rainfall in the area.

No drought conditions are currently present in Alaska.

Most locations across Hawaii reported below normal precipitation through early- and mid-October, although scattered locations reported amounts closer to normal, including Lihue, Molokai, and Kailua-Kona. Hilo has recorded a bit over 3 inches so far this month, which is about half of normal. At this time, no changes were made this week, but if generally subnormal amounts continue, areas of deterioration will be necessary soon.

Virgin Islands

The U.S. Virgin Islands received plentiful rain as Invest 98L moved along to the south of the islands and brought the possibility of some localized urban and small stream flooding. The National Weather Service’s 7-day quantitative precipitation estimates indicated that St. Thomas received 0.5 to 4 inches, St. John received 2 to 4 inches, while St. Croix received 0.5 to 2 inches. All islands remained drought-free. Water levels in wells rose over the past month in response to rainfall.

Pacific Islands

The Republic of Palau received enough precipitation with 2.45 inches at Palau IAP and 1.8 inches at Koror. Water supplies should be satisfactory as these islands need two inches of precipitation weekly to meet minimum water needs as most islands in the USAPI do.

The Mariana Islands all reported enough rain this week or in recent weeks to have adequate water supplies and need an inch weekly. Guam received 11.26 inches, while Rota reported 2.35 inches. Saipan received 2.47 inches at its ASOS station, 1.3 inches at Saipan IAP and 0.58 inches at Saipan (AMME NPS).

Most islands in the Federated States of Micronesia either received adequate rainfall this week or, in many cases, ample precipitation in previous weeks to have adequate water supplies. Kapingamarangi, however, was in D2 and collected just 0.02 inches in the rain gauge.

The Marshall Islands were mixed in terms of precipitation. Ailinglaplap, Majuro and Mili each received more than 4.5 inches for the week, while Wotje and Kwajalein reported 1.9 and 1.66 inches, respectively. Utirik received just 1.12 inches for the week and 2.83 inches in October, indicating that water supplies may be short. All locations were free of drought.

American Samoa received abundant precipitation with 5.02 inches at Pago Pago, 4.63 inches at Siufaga Ridge and 5.98 inches at Toa Ridge.

Looking Ahead

Over the next 5 to 7 days, two general areas are expected to receive heavy precipitation: The Pacific Northwest, and a swath from the southern Great Plains through the Lower Mississippi and Lower Ohio Valleys. Windward areas and higher elevations are expecting 5 to locally over 10 inches of precipitation, with 2 or more inches anticipated for other areas from the Cascades to the Pacific Coast. Meanwhile, 3 to 5 inches are expected from the Red River (South) Valley into eastern Texas and parts of the Lower Mississippi Valley. Elsewhere, totals exceeding 1.5 inches are forecast in the higher elevations of northern and central Idaho and adjacent areas. Moderate amounts (0.5 to locally over 1.5 inches) are expected to fall on the Ohio Valley, the Middle and Upper Mississippi Valley, and remaining locations in the southern half of the Plains outside Deep South Texas. Look for a few tenths to around an inch of precipitation in the northern Sierra Nevada, plus portions of the northern Intermountain West and Rockies. Elsewhere, light amounts at best are anticipated in most of New England, parts of the Mid-Atlantic region, the South Atlantic coastal plain, much of Peninsular Florida, Deep South Texas, most lower elevations across the interior West including the Southwest into central California, plus most of the Great Basin. Daily highs are forecast to average 4 to 8 deg. F below normal from central California through the Pacific Northwest and across the northern Intermountain West. Similar anomalies should affect the Atlantic Seaboard and Piedmont from northern Georgia through southern New England. Meanwhile, unusually warm weather will likely continue across the northern Plains, with daily highs averaging 5 to 10 deg. F above normal from northern Minnesota through the Dakotas and northern Great Lakes into northeastern New York. Also, highs averaging 4 to 8 deg. F above normal are expected from the Southwest through western and southern Texas. Low temperatures should average warmer with respect to normal across most of the Lower-48, especially over the Plains, Mississippi Valley, the Southwest, and the Great Basin. Low temperatures could average 6 to 13 deg. F above normal in the northeastern Great Plains and adjacent areas. The only broad area expecting below-normal lows (by 2 to 5 deg. F on average) stretches from Virginia northward through much of New York.

The Climate Prediction Center’s 6-10 day outlook valid for October 29 – November 1 favors heavier than normal precipitation continuing across the Pacific Northwest, where odds for significantly above-normal precipitation range from 50 to 70 percent. Wet weather is slightly favored across most of the Rockies and Plains as well as parts of central and northern California, northwestern Nevada, and the Pacific Northwest. Wetter than normal conditions are nominally favored across Hawaii. Abnormally dry weather is expected from central and western Texas through central and southern sections of the High Plains and Rockies. Odds for subnormal amounts exceed 50 percent from eastern Arizona through parts of the Texas Big Bend. Meanwhile, warm weather is favored from California, the Southwest, and the Great Basin through parts of the northern Rockies, the High Plains, the northern Great Plains, the Great Lakes, and northern New England. There is a better than 60 percent chance for warmth from southern California into western New Mexico. Cool weather is forecast across the South Atlantic region from Maryland through parts of Florida along with the central and southern Appalachians and the adjacent central Gulf Coast. The Hawaii forecast favors warmth, with chances exceeding 50 percent across the western half of the island chain.