West Coast gets bulk of moisture

After a few warm and dry weeks, heavy precipitation returned to the West Coast states this past week; however, the heaviest amounts fell on California, which is almost completely free of dryness and drought.

At least 1.5 inches of rain fell on a large part of the state including much of the western tier, the higher elevations, and the northern valleys. Much larger amounts fell on isolated higher-elevation with a few spots recording amounts approaching 10 inches (liquid-equivalent).

Several feet of snow has piled up on a few spots across the Sierra Nevada, but overall the snowpack in this area remains significantly below normal. Other areas from northwestern California northward through the Cascades and points west also recorded significant amounts of precipitation, ranging from 0.5 to locally 3 inches.

Similar amounts were more scattered across the rest of the interior West, with the largest totals confined to the highest elevations. As of early Feb. 17, this precipitation has not significantly boosted snowpack in some areas with less than normal amounts, specifically much of the Cascades, south-central Idaho, Scattered locations across western Wyoming, much of west-central and southwestern Colorado, central sections of Utah and Nevada, and the southernmost Rockies.

Farther east, moderate precipitation was fairly widespread over approximately the southeastern quarter of the contiguous states, east of the High Plains and from the central Great Plains, lower Ohio Valley, and mid-Atlantic region southward. Heavier amounts fell on scattered areas across the east-central and southeastern Great Plains.

Some areas of improvement were introduced based either on this past week’s precipitation or a re-assessment of the effects from earlier storms. Specifically, improvements were introduced in the southwestern High Plains. There was more deterioration than improvement overall, however, including areas scattered across the deep South, upper Midwest, northern High Plains, and far southern Texas.

The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the U.S. Department of Agriculture and the National Oceanic Atmospheric Administration. (Map courtesy of NDMC.)

South

Heavy precipitation (3 to locally 5 inches) dropped on a swath through central Arkansas while 1.5 to locally 3 inches were recorded from the lower Red River (south) Valley through the central tier of Arkansas into much of western Tennessee.

Moderate to locally heavy amounts were observed over much of the west side of the lower Mississippi Valley and portions of eastern Texas. Amounts of several tenths of an inch to locally around an inch were reported across a large part of central and north-central Texas and most of Oklahoma east of the Panhandle.

Little or no precipitation was reported across the Texas and Oklahoma Panhandles, western Texas, and deep south Texas. This pattern supported improvement across a smaller area of Arkansas and along with scattered spots across southern Oklahoma.

Deterioration was fairly common in areas that missed most of the precipitation including the ArkLaTex region and deep south Texas. Intensifying dryness in the latter area prompted the introduction of exceptional drought in parts of Jim Hogg and Brooks counties. D4 already existed in part of interior northeastern Arkansas and the southernmost reaches of the Texas Big Bend. Meanwhile, extreme drought expanded to cover most of south-central and Deep South Texas, portions of southern Oklahoma and northeastern Texas, most of northeastern Arkansas, and a few smaller scattered areas in western Arkansas and northeastern Oklahoma. During the past 90 days, fewer than 2 inches of precipitation have fallen on western Oklahoma, the Texas Panhandle, and the southwestern tier of Texas from the Big Bend into much of deep south Texas.

Midwest

Central and northern portions of the Midwest were almost precipitation-free, prompting some deterioration across the upper Midwest from northern Illinois across Iowa into southern Minnesota.

Farther south, heavier totals (1.5 to locally 3 inches) were reported across central and southern Missouri. This pattern led to improvements in a swath including central and southern Missouri.

High Plains

Moderate to locally heavy precipitation fell on part of eastern Kansas, and scattered light to moderate amounts fell on the rest of the southern tier of the region.

Farther north scant precipitation led to large areas of degradation across a large proportion of Wyoming and central through eastern Montana, with more limited deterioration introduced across parts of Nebraska and South Dakota.

This resulted in moderate drought or worse covering a swath across most of Nebraska and adjacent areas westward through most of Wyoming and the northern, central, and western sections of Colorado.

Severe drought or worse is widespread from western Nebraska across the southern tier of Wyoming through northern and central parts of Colorado.

West

Widespread deterioration was introduced across central and eastern Montana, leaving most of the state entrenched in abnormal dryness to severe drought, with an area of extreme drought in parts of north-central Montana.

Elsewhere, only minor adjustments were made as light to moderate precipitation fell on a large part of the areas of dryness and drought – enough to preclude widespread deterioration, but not sufficient to justify much improvement.

Only a few parts of central and south-central New Mexico were improved, primarily from the effects of precipitation. Severe to extreme drought now extends across most of the western half of New Mexico.

Looking ahead

Light to moderate totals are anticipated over a large part of the interior West, including the Great Basin, much of the northern Intermountain West, and the higher elevations across the Rockies.

Little or no precipitation is expected across the northern and southern. Above-normal temperatures are expected from the Southwest through most of the Plains, with many locations expected to average 5 to 11 degrees Fahrenheit above normal. In contrast, subnormal temperatures are forecast in the northernmost Plains, where daily highs could average as much as 9 degrees below normal.

The 6- to 10-day outlook for Feb. 24 to 28 depicts increased chances for below-normal precipitation across much of the southern tier of the contiguous U.S., from the extreme southern Rockies through the central Gulf Coast. Chances for abnormal dryness exceed 40% across most of Texas and some adjacent areas.

Farther north, heavier than normal precipitation is at least nominally favored in the central Plains. Warmer than normal weather is expected to dominate the contiguous 48 states from the Appalachians to the Intermountain West, with chances for significantly warmer than normal conditions topping 80% in western Texas.

Richard Tinker is with the National Oceanic Atmospheric Administration, National Weather Service, National Centers for Environmental Prediction, and Climate Prediction Center.