Tools used in the U.S. Monthly Drought Outlook (MDO) include the Climate Prediction Center (CPC) updated temperature and precipitation outlooks for July 2023, various short- and medium-range forecasts and models such as the 7-day quantitative precipitation forecast (QPF) totals from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC extended-range forecasts, dynamical model output, July climatology, and initial conditions such as soil moisture and snowpack. The U.S. Drought Monitor valid on June 27, 2023 was used for initial drought conditions. El Niño conditions have developed across the Equatorial Pacific, and the atmospheric response to these conditions is anticipated to impact the forecast.

Generally cooler than average temperatures across the southern half of the Western Region allowed for a slow continued release of the generous winter snowpack, with streamflows remaining high across much of California and the Great Basin. Across the Northwest, early season heat caused a rapid early melting of a more meager snowpack, and streamflows are below average across Washington, western Oregon, northern Idaho, and northwestern Montana. Widespread heavy rainfall across the northern Rockies and northern High Plains helped ease drought conditions across central and eastern Montana, though drought conditions have begun to slowly expand west of the Cascades. July is a climatologically dry time of year for most of the Western Region, except for the Four Corners states, where the Southwest monsoon typically begins ramping up. Due to the dry climatology, little change in the drought depiction is favored for the West during July, though some further expansion is possible west of the Cascades. Across the Southwest, forecasts at various timescales during July all favor below-average monsoonal convection, with periods of excessive heat ongoing and favored to continue through the first two weeks of the month. Therefore, despite the favorable antecedent conditions across the Four Corners, areas of drought development are possible, especially for south-central New Mexico, where conditions are already abnormally dry.

Forecast confidence is moderate to high for the Western Region.

During the past 30 days, a sharp west-east gradient in precipitation set up across the High Plains region, with widespread heavy convective rainfall easing drought conditions across western portions of the Plains, and more meager rainfall to the east resulting in drought persistence and expansion. July is a wet time of year for the Plains, with generous Gulf of Mexico moisture able to penetrate the entire region, and climatological ridging across the central US providing a focus for periods of organized convective activity. During the first week of the month, widespread rainfall is forecast along a frontal zone, which should bring additional relief across eastern Wyoming and Colorado, and southern South Dakota southward across Kansas. These same areas remain favored for above-normal wetness during Week-2, and for the entire month of July, with the signal more muted across Colorado, southwestern Kansas, and North Dakota. Based on these outlooks, further drought reduction is favored for most of the High Plains, with persistence maintained in the outlook across southern Kansas, northeastern South Dakota, and North Dakota, where the wet signal is less pronounced.

Forecast confidence is moderate to high for the High Plains Region.

Substantial rainfall during the last 30 days resulted in widespread drought improvements for northern Texas and western Oklahoma, though drier conditions and hot temperatures caused some expansion of drought and abnormal dryness across eastern Oklahoma, eastern Texas, and northern Louisiana. July remains a fairly wet time of year for northern Texas and western Oklahoma, though conditions across eastern Texas tend to be drier in July than in May and June. At the close of June, a strong heat dome developed over Texas and the lower Mississippi Valley, bringing widespread heat and record temperatures, as well as reduced precipitation. A continuation of this pattern through at least the first half of July is favored, and with 30- and 60-day percent of normal precipitation dropping well below normal across much of Texas, the region is primed for widespread drought development. Therefore, drought development in areas already abnormally dry is favored across central and southern Texas. There is less confidence in development across eastern Texas due to a more mixed signal, and drought improvements are indicated for Louisiana, where climatological summer convective activity should remain fairly robust. Further east, a pronounced wet signal across the Tennessee Valley favors elimination of the small remaining areas of drought.

Forecast confidence is moderate for the Southern Region.

Persistent below-normal precipitation across the Midwest Region has resulted in significant increases in drought coverage, despite near- to below-normal temperatures slowing the onset of impacts. As of the June 27 USDM, nearly 65 percent of the Midwest Region is currently experiencing drought conditions, a massive increase from just 6 percent coverage 3 months ago. Towards the end of June, a pattern change brought an increase in convective activity to the eastern Corn Belt, though 30-day percent of normal precipitation remains meager outside of central Kentucky and central Ohio. Forecasts at various time scales during July indicate that a big pattern change is in store, with widespread soaking rainfall favored across the Corn Belt during the first week of the month, and a maintained wet signal during Week-2. This increased precipitation favors easing impacts and drought reduction across Iowa, Missouri, Illinois, Indiana, Ohio, Kentucky, and southern Michigan, though given the high 90-day deficits, substantial drought coverage will likely remain high at the end of the month. In contrast, the first week of July looks dry for the Great Lakes region, and the signal is weaker throughout July. Therefore, drought persistence is favored, with some expansion possible across Wisconsin and northern Michigan.

Forecast confidence is high for the Corn Belt and low for the Great Lakes in the Midwest Region.

Little drought coverage is currently in place across the Southeast region, with the last remaining drought areas across the western Florida Peninsula removed by the robust onset of the seabreeze convective regime. Increased rainfall during the latter part of June also eased drought conditions across northern Virginia. 30-day percent of normal values show areas of dryness remaining across northern Virginia, and developing across western Virginia and the eastern Carolinas. Given that July is the climatologically hottest month of the year, these regions are vulnerable to spotty short term drought development if they continue to miss out on summer convection. It is difficult to ascertain on the monthly time scale where any such regions would set up. The CPC revised monthly outlook favors above-normal rainfall for the Appalachians and Piedmont regions, with equal chances maintained across Florida and the South Atlantic coastal plain. Therefore, due to the generous convective climatology, no drought development is favored on the outlook, despite the potential for spotty development across the eastern Carolinas should certain areas miss out on rainfall.

Forecast confidence is moderate for the Southeast Region.

Similar to the Midwest, a blocking pattern favored very dry, if not warm conditions to persist across much of the Northeast Region, resulting in widespread drought development. Onshore flow across Maine brought increased moisture and drought improvements to Maine, and a more unsettled pattern across the mid-Atlantic towards the end of June began to bring some spotty relief. During the first week of July, soaking rainfall is favored to overspread most of the Northeast region, which should continue the easement of drought and abnormal dryness that began at the end of June. Spotty drought expansion may still occur during early July across Connecticut, where more meager rainfall is expected, but given the wet pattern overall, it is unlikely for this drought to persist through the end of the month. A continued wet pattern is favored in the CPC 8-14 day outlook, and the revised CPC July monthly outlook favors above-normal precipitation for the entire Northeast region. Therefore, widespread drought reduction is anticipated, though some drought may linger across the mid-Atlantic region where current deficits are the highest.

Forecast confidence is moderate to high for the Northeast Region.

A small area of moderate drought developed in Alaska’s Yukon Flats region due to above-normal temperatures, dry conditions, and long periods of daylight. Due to the high sun angles this time of year, drought conditions can be slow to ease across Alaska absent a clear wet signal. Therefore, persistence is favored, though no additional development is anticipated. Across Hawaii, El Niño conditions are strongly associated with below-normal precipitation due to subsidence and reduced trade winds. Therefore, gradual drought expansion is likely, particularly for leeward portions of the Big Island that are already abnormally dry. Across Puerto Rico, despite El Niño conditions typically favoring a drier Caribbean region, NMME forecasts indicate a continuation of an already active easterly wave regime across the Atlantic and northern Caribbean islands, possibly due to reduced African easterly jet and Saharan Air Layer activity, and a northward displaced midlatitude ridge. Therefore, drought reductions are indicated for the small area of drought coverage across northern Puerto Rico.

Forecast confidence is moderate for Alaska, moderate to high for Hawaii, and low to moderate for Puerto Rico.

Forecaster: Adam Allgood

Next Monthly Drought Outlook issued: July 31, 2023 at 3PM EDT