Precipitation varies widely across US

Precipitation again varied widely across the Lower 48 this week, which is not unusual during the summer. Across the interior West, monsoon rains were not as intense as last week, but remained heavier than normal. Several times the normal amount soaked most areas in the western half of the Four Corners Region, much of Nevada, southeastern California, reaching as far north as southeastern Oregon and Wyoming.

Other areas receiving widespread heavy rains (and thus some improvement from recent dryness) included Deep South Texas and northwestern Nebraska. Parts of Deep South Texas recorded over 10 inches of rain, and 2 to 3 inches were common across northwestern Nebraska.

Other areas observing light rain at best included part of the Upper Midwest, the north-central and south-central Plains. Conditions were seasonably dry along the West Coast.


Last week’s precipitation, though variable, followed the same general pattern as the precious week. Heavy rains drenched much of the eastern reaches of the region while lesser amounts and localized deterioration were noted farther west. On significant exception was Deep South Texas, where heavy to intense rainfall brought significant improvement to areas of abnormal dryness and drought. Amounts exceeding 2 inches were widespread south of a line from Webb and LaSalle counties eastward through San Patricio County, and amounts of 5 to locally over 10 inches drenched areas north of the Mexican border counties. This prompted nearly universal 1-category improvements on the Drought Monitor, with small areas of 2-category improvement where rainfall was heaviest. Extreme drought (D2) or worse are now confined to areas north and west of Duvall County.

Enough rain fell on central and northern Texas to keep areas of deterioration small, but little rain fell from the Red River (South) into northern Oklahoma, where larger areas of intensification were observed. Broad areas of exceptional drought (D4) still cover much of a large area from the southern Texas Panhandle southeastward toward the Gulf Coast. Over the last half-year, rainfall deficits of 8 inches to locally over a foot have affected areas of central Texas near and south of Dallas/Ft. Worth to the Gulf Coast.


Similar to the South region, rainfall in the Midwest was hit-and-miss last week. A mix of deterioration an improvement resulted, but dryness and drought remained considerably more widespread along the western tier of states in the Midwest region. Improvement was indicated in relatively small, scattered areas across the region while deterioration was fairly common from central Illinois and Iowa northward through most of northwestern Wisconsin. Several bands of extreme drought (D2) persist in the western tier of the Region, with small areas of extreme drought (D3) affecting northwestern Iowa and southwestern Missouri.

High Plains

Light rainfall at best fell on Kansas and farther north across the Dakotas. In contrast, heavy precipitation augmented by intrusions of monsoonal moisture covered large areas from Colorado and Wyoming eastward into western Nebraska. Dryness and drought eased in these areas, with improvement most widespread across the southern half of Wyoming and in the Colorado High Plains. Precipitation in these areas generally exceeded an inch, with 2 to 4 inches falling on several areas from southeastern Wyoming into northwestern Nebraska.

Outside of the band of heavy precipitation that brought some improvement to Nebraska and adjacent areas, little or no rain fell on central and southern Kansas, and across most of the Dakotas, with South Dakota recording less rainfall than areas to the north. As a result, dryness persisted or intensified in these areas. Most of the Dakotas and the eastern tier of the Region measured near or below half of normal for the last 3o days, with several patches across the central Dakotas and southeastern Kansas receiving 25% of normal or less. In sharp contrast, most areas from central Wyoming through eastern Colorado and western Nebraska reported 150% to locally over 300% of normal since mid-July.


Ample rains from the North American Monsoon continued through mid-August. Seven-day totals of 1 to 3 inches, with isolated higher amounts, fell across southwestern New Mexico and Arizona northward through much of the central and eastern Great Basin, and the western half of Utah. As a result, several large areas of improvement were noted this week, with the heaviest rains and most widespread improvement covering Arizona.

After an extended period of serious drought, the heavy rains have prompted broadscale improvement in monsoon-affected areas. Two-category improvements over the past 4 weeks have occurred in areas recording the heaviest rainfall. Meanwhile, drought and dryness have been changing in the opposite direction across the northern tier. Most notably, abnormal dryness and moderate drought have been expanding across central and western Montana due to deficient precipitation and well above normal temperatures, while intensification has been slower and covers smaller areas in Idaho and Washington. Most of the Pacific Coast states have been dry and periodically hot as well, but this is their dry season, so totals are not far removed from normal.