With the main storm track over the northern states, strong high pressure in the upper levels of the atmosphere dominated the southern U.S. during this U.S. Drought Monitor (USDM) week. Weak fronts that penetrated into the Southeast stalled out and provided an instability zone for scattered showers and thunderstorms. Convective showers benefited Florida while Tropical Storm Arlene rain brushed Deep South Texas and monsoon showers picked up over parts of the Southwest. Most of the southern Plains continued hot and dry, with much above-normal temperatures spreading across the central half of the country.
The Upper Midwest, Northeast, and Mid-Atlantic: The last 30 days have been drier than normal for much of western New York, western Pennsylvania, and central Maryland to Delaware and southern New Jersey. But the dryness over the Maryland-Delaware area extended further back in time, so D0 expanded in central Maryland, northern Virginia, and adjoining south central Pennsylvania, and a spot of D2 was added to Maryland’s southeastern shore to reflect the greatest precipitation deficits and low groundwater. An A impacts designation was placed over the Maryland D0 with AH impacts over the DelMarVa D1-D2 and the rest of Virginia, leaving the southern New Jersey D0 area free of an impacts designator.
Southeast: Beneficial (1 to 4+ inch) rains prompted the contraction of D0 in northwest Alabama, the pullback of D3 over southeast Alabama and D4 over southeast Georgia, and improvement of D3 in northern Florida and D1-D2-D3-D4 in coastal central to southern Florida. But conditions deteriorated over the Carolinas, where D3 was added along the North Carolina coastal plain and D2-D3 expanded from southern coastal North Carolina and parts of coastal South Carolina. D1 expanded across most of South Carolina and into the Catawba Basin of western North Carolina, with minor expansion of D0 in western North Carolina. The H impacts area from northern Alabama to North Carolina was reconfigured to accommodate expanded AH impacts in North Carolina.
The Plains: Improvement of the D3 and D4 areas occurred over southern Texas where a month’s worth of rain fell this week, especially in the Brownsville area. D0 and D2 were pulled back in the Wise and Upshur county areas, respectively, where locally beneficial rains fell. But conditions deteriorated elsewhere in Texas with D4 expanding to cover all of the panhandle as well as expanding in Harrison and Bosque counties, and D3 expanding in central Texas. In Oklahoma, the D0 hole was filled in over Garfield County, D1 expanded across eastern Oklahoma and adjoining southwest Arkansas, and D2-D3 expanded in south central to Southeast Oklahoma. D0 expanded in southeast Kansas where rainfall has been below normal and temperatures above normal for the last 1 to 4 weeks.
The West: Although streamflows were fine, D0 expanded in southeast Utah to reflect precipitation deficits and satellite-observed impacts on vegetation. In Colorado, a spot of D4 was added to Alamosa County were precipitation deficits were most severe, and D0-D1-D2 in Cheyenne County expanded to reflect worsening local impacts.
Hawaii, Alaska and Puerto Rico: Above-normal precipitation at many time scales and above-normal streamflow prompted the pullback of D0 in central Alaska. Northwest Puerto Rico has been dry for the last 7 to 30 days, but wet at longer periods. However, low streamflows coupled with the below-normal precipitation prompted the addition of D0H to that area. No changes were made to the Hawaiian depiction this week.
Looking Ahead: The weather pattern of the last few weeks will continue for the next two weeks, with an upper-level ridge over the south and the storm track keeping to the northern states. Cool fronts will weaken as they try to penetrate the southern high pressure, providing instability zones for showers. Monsoon rain is expected for the Southwest and summertime convection should bring rain to Florida. For the next 5 days (July 6-11), an inch or more of rain is expected in a band from the central Rockies to central Plains, across parts of the Southeast to Mid-Atlantic coast, and over much of the Florida peninsula. Monsoon showers may drop up to half an inch of rain in parts of the Southwest, with other parts of the Southeast drought areas possibly receiving a quarter inch to an inch of rain. The northern Plains to western Great Lakes could see half an inch of rain, while the southern Plains should remain mostly rain-free. Temperatures are expected to be above normal for much of the country.
The CPC 6-10 day outlook and 8-14 day outlook indicate above-normal precipitation will fall over the Rockies, central and northern Great Plains, southern Great Lakes, and Florida peninsula into the Southeast, while dry weather should dominate across parts of the Southwest, Mid-Atlantic, and much of the southern Plains. Below-normal temperatures are expected along the west coast while warmer-than-normal temperatures should dominate across most of the country east of the Rockies. Northern Alaska is expected to be dry and southern Alaska cool and wet.
Author: Richard Heim, NOAA/NESDIS/National Climatic Data Center
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
A ... Agricultural
H ... Hydrological