California and National Drought Summary for November 14, 2017

Summary

November 16, 2017 - It was a dry week for the Nation as a whole. Widespread heavy precipitation was restricted to the central and northern West Coast from the Cascades and northern Sierra Nevada westward. A few patches near the coast recorded 6 to 12 inches of precipitation. Across the remainder of the contiguous states, only a few small areas reported over 1.5 inches, with most locations observing little or none. As a result, short-term dryness continued to develop and expand across the south-central and southeastern U.S. as 30- to 90-day precipitation deficits continued to steadily increase, overcoming the wet weather that had squelched dryness impacts in much of these regions several months ago.

Northeast

Light precipitation fell on the mid-Atlantic and central Appalachians as well as eastern sections of Maine. Little or none was reported elsewhere. With cooler weather arriving and the growing season generally over, deterioration progresses slowly this time of year, and no changes were introduced from Virginia and West Virginia northeastward.

Southeast

In a swath across central Georgia, and across south-central Virginia and adjacent areas, 1 to locally near 2 inches of precipitation fell; only a few tenths of an inch, if any, was recorded elsewhere. With 30- and 60-day precipitation shortfalls steadily increasing, broad D0 expansion was introduced across much of the southern half of Georgia, the east-central Carolinas, the eastern Florida Panhandle, the northwest Florida Peninsula, and smaller areas in northern and western Alabama. More modest expansion of moderate drought affected Georgia, both near the central South Carolina border and in southwestern parts of the state. Little or no rain fell during the past month in parts of northern Florida and southern Georgia, and totals for the past 60 days are near or below half of normal in most of the dry areas. Notable longer-term (90-day) deficits, however, are limited to the regions of moderate drought.

South

A band of 1 to 2 inch rainfall amounts extended from north-central Texas to southeasternmost Arkansas, but most of the region was dry, receiving a few tenths of an inch, if any. No measurable precipitation has fallen during the last 30 to 45 days in southwestern Kansas, western Oklahoma, the Texas Panhandle, and interior southern Texas while 90-day deficits are generally between 4 and 8 inches from central Mississippi westward to northeastern Texas and northward through eastern Oklahoma, much of Arkansas, and the southern half of Missouri. The month or more without measurable precipitation was stressing winter wheat in and near western Oklahoma, prompting northwestward D0 expansion into the area. Farther east, the longer-term deficits prompted broad deterioration (D0 to D2) from central Missouri southward through central sections of Louisiana and Mississippi. D2 was expanded into the St. Louis, MO area, where low streamflows and longer-term precipitation deficits (4 to 6 months) exist. D2 was also expanded to cover areas from southern Missouri southward into northeast Texas and northwestern Louisiana, where 3-month deficits are the largest. A small area in west-central Arkansas and adjacent Oklahoma accumulated a deficit exceeding 10 inches since mid-August.

Midwest

Only a few tenths of an inch of precipitation, if any, was observed region-wide; however, this time of year, development and intensification of dryness occurs gradually, so few changes were made to the depiction. Cumulative changes over the  past few weeks prompted the removal of D1 from northeast Ohio and D0 from northwestern Ohio while some expansion of dryness and moderate drought was brought into southeastern Iowa and adjacent sections of Missouri and Illinois.

High Plains

Cold weather, accompanied by little or no precipitation, kept dryness and drought unchanged across the Dakotas and Montana, with extreme drought persisting in portions of western South Dakota and northeastern Montana.

West

Dryness continued to slowly improve east of the Cascades in Washington and Oregon, eliminating D1 in north-central Washington and restricting D0 to areas recording less than 1.5 inches of precipitation during the past 30 days. Farther south, no measurable precipitation has fallen for at least the last 30 days on the central and western Four Corners States, Nevada, and the southeastern half of California. This is not unusual here in late autumn, and while notable impacts are lacking, increasingly impressive dryness over the past few months induced some D0 expansion in southeastern Monterey County, CA and in the drier areas of southwestern Utah, southeastern Nevada, and part of southeastern California.

Alaska, Hawaii, and Puerto Rico

Increased rainfall during October and early November seems to have eased agricultural stress in the dry areas of Hawaii, according to impact reports. This week’s depiction improved through a lot of the state, though relief has been less widespread on the Big Island. Alaska and Puerto Rico were unchanged, with no dryness depicted.

Looking Ahead

During the next 5 days (November 16-20), Moderate precipitation at best is expected for most of the country. Amounts of 0.5 to locally approaching 2.0 inches are expected in the Northeast, the northern and central Appalachians, the eastern Great Lakes, and the central and northern sections of Ohio, Indiana, and Illinois. Farther west, more than 0.5 inch is forecast from the Sierra Nevada and the Cascades westward to the Pacific Ocean, with heavy amounts anticipated in the typical orographically-favored areas, specifically along the coast and on the windward (western) slopes of the mountains. Between 5.0 and 8.5 inches could fall on the Washington Cascades, northwestern Washington, the northwestern and west-central California Coast, and the Sierra Nevada. In addition, 0.5 inch or more is expected in some of the higher elevations of western Colorado, western Wyoming, central and north-central Utah, northeastern Nevada, and parts of Idaho. Isolated amounts of 2.0 to 4.5 inches could be dropped on the highest elevations and windward slopes.

During the 6-10 day period (November 21-25), odds favor above-median precipitation only across the Florida Panhandle, the northern Intermountain West, and the northern half of the West Coast States. Below-median precipitation is anticipated elsewhere except in the southern half of the High Plains, the northern Plains, most of the Great Basin, and the Southwest, where neither abnormal wetness nor dryness is favored. Warmer than normal weather is expected from the Pacific Coast eastward into the upper Mississippi Valley, the central Great Plains, and central Texas, with subnormal temperatures favored in most areas from the eastern Great Lakes and southern half of the Mississippi Valley eastward to the Atlantic Coast.

Author(s):
Richard Tinker, NOAA/NWS/NCEP/CPC

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Dryness Categories

D0 Abnormally Dry—used for areas showing dryness but not yet in drought, or for areas recovering from drought.

Drought Intensity Categories

D1 Moderate Drought

D2 Severe Drought

D3 Extreme Drought

D4 Exceptional Drought

Drought or Dryness Types

S Short-Term, typically less than 6 months (e.g. agricultural, grasslands)

L Long-Term, typically greater than 6 months (e.g. hydrologic, ecologic)
Source: National Drought Mitigation Center