Tools used in the U.S. Seasonal Drought Outlook (SDO) include the Climate Prediction Center (CPC) temperature and precipitation outlooks for June and June-July-August (JJA), 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 (ERFs), dynamical models at the monthly and seasonal time scale, climatology for JJA, and initial conditions such as soil moisture. The U.S. Drought Monitor valid on May 14, 2024 was used for initial drought conditions. ENSO-neutral conditions are likely through much of the JJA season, with the potential to transition to La Niña toward the end of August.



The Western region has experienced a combination of both degradation and improvement of abnormal dryness (D0) and drought (D1-D4), as depicted in the U.S. Drought Monitor (USDM) since mid-April. The degradation of abnormal dryness and drought was limited to parts of the Pacific Northwest and Northern Rockies, where snowpack is running below normal and soil moisture has continued to decline due to many locations seeing less than 50 percent of their normal precipitation over the past 30 days. On a positive note for Oregon, despite some increase in abnormal dryness across northern parts of the state, moderate drought was downgraded to abnormal dryness (D1 and D0 as depicted in the USDM, respectively), making it the first time since early December 2019 that the state has been drought-free. Elsewhere across the Western region, from the northern Great Basin southward to the Four Corners region, snowpack is near to above normal and deep soil moisture is above normal for most locations. Looking ahead to the June-July-August (JJA) season, warmer and drier than normal conditions are favored for the western Great Plains and throughout the Intermountain West. As such, drought persistence is broadly favored throughout the West. Given wet antecedent soil moisture conditions, near to above normal snowpack, and favorable extended-range precipitation outlooks across much of the Great Basin, drought development is not favored for central portions of the Intermountain West. However, the same cannot be said for parts of the Pacific Northwest, Northern Rockies, and Four Corners, where soil moisture conditions have begun to deteriorate in several locations, particularly in the shallower depths, as the warm season has progressed. Therefore, along with the increased likelihood of drought persisting, drought conditions are also favored to expand in these areas. It is important to note, however, that the onset of the North American Monsoon (NAM) typically occurs in late-June and early-July in the Southwest, which increases uncertainty in the JJA drought outlook for the Four Corners region. Despite the NAM's historical onset during JJA, precipitation is likely to be spotty in nature, as is typical of the NAM, and areas that miss out on the precipitation will subsequently likely experience deteriorating conditions.



Forecast confidence is moderate to high for central and northern parts of the Intermountain West and low to moderate for the Four Corners in the Western region.



Drought is forecast to persist across western portions of the Central and Northern Plains, despite JJA being a very wet time of year for these regions. Warmer and drier conditions are favored for the JJA season as a whole and in areas of the central High Plains and central Rockies, where antecedent dryness exists at the onset of the JJA period, drought development is also favored. In the eastern Central Plains and northern North Dakota, precipitation and temperature signals are predominantly lacking for both June and JJA. Given this is also climatologically their wettest time of year and the antecedent wet conditions, with several rounds of improvements in recent weeks in the USDM depiction, drought removal and improvement is favored for these eastern- and northern-most areas of the High Plains region.



Forecast confidence is moderate for the High Plains region.



Parts of eastern Texas and Oklahoma and the Lower Mississippi Valley have received in excess of 10 inches of rainfall in the last month (locally more than 20 inches in eastern Texas), which has resulted in widespread flash flooding and river flooding across the Lower Mississippi Valley and eastern Texas. Unfortunately, much of the rain fell over areas not experiencing drought conditions, although some localized fringe areas of central Texas, eastern Oklahoma, and the Tennessee Valley experiencing abnormal dryness and drought conditions did see some improvements over the past 30 days. Conversely, there have been some areas that have seen some degradations as well, particularly parts of southern Texas, northwestern Oklahoma, and the southern Appalachians. Looking ahead to JJA, remaining patches of moderate drought (D1 as depicted in the USDM) in the Middle Mississippi Valley and Southern Appalachians are likely to become drought-free by the end of August, due to favorable monthly and seasonal precipitation outlooks. The opposite is true for western portions of the Southern Plains, where most locations have missed out on heavier rainfall totals over the past month, despite May being historically a wet time of year. Warmer and drier conditions are favored for June and JJA across the western Great Plains and given the antecedent dryness already in place, portions of western Texas and Oklahoma are likely to see drought persist and expand in coverage through the end of August. As we get closer to the latter half of the season, however, we will need to keep an eye on the tropics, especially as it pertains to the Gulf Coast. El Niño Southern Oscillation (ENSO) is favored to be in its neutral phase throughout much of the JJA season (i.e. near normal sea surface temperatures in the tropical Pacific Ocean). When coupled with warm sea surface temperatures (SSTs) in the Caribbean Sea and Gulf of Mexico, which are likely during the next few months, this has the potential to create an environment more conducive to tropical activity.



Forecast confidence is moderate to high for the Southern region.



The last month has seen week after week of improvements in the drought depiction in the Midwest region. This is not unexpected, given May is the climatological start to a wet time of year, which typically lasts through at least the end of JJA. However, climatology has been underperforming in recent years. For example, Iowa saw a welcome sight in the drought depiction starting in early May with the removal of exceptional drought conditions (D3 as depicted in the USDM). Exceptional drought was present somewhere in the state of Iowa going all the way back to late-June 2022. Improvements are likely to continue at least early into the JJA season, as long-term drought indicators continue to improve from recent precipitation. JJA temperature and precipitation signals are lacking, however, particularly across parts of the central Corn Belt and Upper Midwest. As such, climatology is favored to be the primary driving force behind any additional improvements and no drought development, or redevelopment is favored by the end of August.



Forecast confidence is moderate to high for the Midwest region.



In the Southeastern region, moderate drought (D1 as depicted in the USDM) developed in the Florida Peninsula, with 4 to 6 inch rainfall deficits over the past 60 days. Abnormal dryness (D0 as depicted in the USDM) has also popped up in the southern Appalachians and portions of the Piedmont and Coastal Plain of Virginia and North Carolina. However, many of these areas from northern Georgia northeastward to Virginia have received some beneficial rainfall in the days leading up to the JJA SDO release (May 16). Looking ahead to JJA, moderate drought in the Florida Peninsula is forecast to be removed, with the remainder of the Southeast region expected to remain drought-free by the end of August. Despite warmer than normal temperatures being favored throughout the region during JJA, above normal precipitation is also favored throughout the Southeast. Additionally, with ENSO-neutral conditions through most (if not all) of the forecast period and warm SSTs in the tropical Atlantic, Caribbean, and Gulf of Mexico, conditions may become more conducive for tropical activity, especially toward the latter half of JJA. There is some uncertainty with respect to the strength of the sea breeze circulation in Florida, which typically starts up in June, as warmer than normal SSTs could act to weaken the circulation. However, this potential is offset by aforementioned factors that are suggestive of drought removal by the end of August.



Forecast confidence is high for the Southeast region.



Although some abnormal dryness (D0 as depicted in the USDM) is present at the start of the JJA season across portions of West Virginia, western New York, and northern Maine in the Northeastern region (due to deteriorating soil moisture, stream flows, and subnormal snowpack), conditions are not forecast to deteriorate to drought by the end of August. However, there could be some extended dry and wet periods during the JJA season, so some periods of localized degradation and improvement cannot be completely ruled out as the season progresses along. Nonetheless, the Northeast is forecast to remain drought-free by the end of August.



Forecast confidence is moderate for the Northeast region.



Drought is favored to develop in the southeastern Alaska Panhandle in areas experiencing abnormal dryness (D0 as depicted in the USDM) at the start of the JJA season. Below normal snowpack and rainfall deficits accumulating over the past 4 months have resulted in the antecedent dryness and these conditions are likely to be exacerbated, as the region is entering into its driest time of year climatologically and with warmer than normal temperatures being favored throughout JJA.



Forecast confidence is moderate to high for Alaska.



Drought persistence is favored for the eastern Hawaiian Islands, with drought development also favored in regions experiencing abnormal dryness (D0 as depicted in the USDM) and on the leeward slopes of the islands. Antecedent dryness, dry seasonal precipitation signals, and JJA being a climatologically dry time of year support this persistence and development forecast. Additionally, summer rainfall is typically diminished during ENSO-neutral to La Niña transitions (i.e. transition to cooler than normal SSTs in the tropical Pacific), further supporting the degradation potential.



Forecast confidence is high for Hawaii.



Puerto Rico is drought-free at the start of the JJA season and is forecast to remain drought-free by the end of August. Soil moisture and stream flows are above normal and, with the exception of the northwestern corner of the island, 90-day rainfall surpluses of more than 8 inches are widespread. Additionally, long-range forecasts show enhanced probabilities of above normal precipitation and ENSO-neutral conditions coupled with warmer than normal SSTs in the tropical Atlantic suggest the potential for an environment that may be more conducive to tropical activity as the season progresses.



Forecast confidence is high for Puerto Rico.



Similar to Puerto Rico, the U.S. Virgin Islands (USVI) are likely to remain, as they are at the start of the JJA period, drought-free by the end of August. Although Saint John and Saint Thomas has experienced wet and dry periods over the last 6 months, the USVI as a whole has seen near to above normal precipitation for the period. Furthermore, the antecedent conditions, the favorable long-lead precipitation outlook, and the potential for a more favorable tropical activity support an increased likelihood that the islands will remain drought-free by the end of the season.



Forecast confidence is high for the U.S. Virgin Islands.



Forecaster: Adam Hartman



Next Seasonal Drought Outlook issued: June 20, 2024 at 8:30 AM EDT