Tools used in the U.S. Seasonal Drought Outlook (SDO) included the Climate Prediction Center (CPC) temperature and precipitation outlooks for October through December (OND) 2019, various short- and medium-range forecasts and models such as the 7-day quantitative precipitation forecast (QPF) from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC extended-range forecasts (ERFs), the Week 3-4 outlooks and tools from CPC, dynamical models at the monthly and seasonal time scales, the 384-hour total precipitation forecasts from several runs of the GFS, climatology for the OND season, and initial conditions such as soil moisture. The September 17 U.S. Drought Monitor drought areas were used. ENSO-neutral is favored to continue through the Northern Hemisphere fall (75-percent chance), with a 55 to 60-percent chance of ENSO-neutral continuing through the winter.

Outside of a small area of moderate drought in southern West Virginia, the Northeast region remains drought free. Abnormal dryness (D0) has expanded northward into much of West Virginia, Maryland, Delaware, southeastern Pennsylvania, and southern New Jersey, however, due to recent warmth and dryness. The pattern of above-normal temperatures and suppressed rainfall is favored to continue through the end of September, which increases the potential for rapid short-term drought development. Beyond this period, the CPC October and OND outlooks both favor enhanced odds for above-median precipitation across the mid-Atlantic along and east of the ridge-and-valley Appalachians, and as evapotranspiration rates decrease, conditions become more favorable for soil moisture recharge. Therefore, while drought development during the OND period is likely across southern portions of the Northeast region, much of it may be alleviated by the end of December. Expansion of drought is favored for southern West Virginia, where the monthly and seasonal guidance maintain equal chances for below-, near-, and above-median precipitation.

Forecast confidence is low to moderate for the Northeast Region.

A regime of widely scattered summer convection and above-normal temperatures prompted numerous changes to drought conditions across the Southeast region, with drought relief across parts of central and southern Alabama and Georgia combining with new drought development along the Piedmont and southern Appalachians. Heavy rainfall from Hurricane Dorian reduced drought conditions along the coastline of the Carolinas. 60-day observed percent of normal precipitation values indicate that a region encompassing most of Virginia, the western Carolinas and Tennessee southward through much of Florida has rapidly dried out over the past two months, and correspondingly there has been a substantial increase in D0 coverage on the latest drought monitor. Mostly dry conditions are favored for much of the Southeast over the next 7 days, with near to below-normal rainfall anticipated to continue in Week-2. Combined with persistently high temperatures, these conditions favor the potential for a late-season flash drought in the Southeast. The persistence of any potentially developing drought through the end of December is highly uncertain, particularly along the Atlantic Seaboard and Piedmont, where the monthly and seasonal outlooks favor above-median precipitation and the potential for additional tropical cyclone activity remains. Therefore, drought development indicated on this outlook is limited to a region extending from the Chattahoochee River Basin northeastward into the central Appalachians, although early in the period the drought conditions could potentially be more widespread. Given the anticipated dryness early in the period offset by the enhanced chances for above later in the fall, persistence of existing drought areas is maintained for the small D1 areas extending from North Florida through southern Virginia.

Forecast confidence is low for the Southeast Region.

In the Midwest Region, below-normal temperatures and above-median precipitation across the upper Mississippi River Valley contrasted sharply with recent heat and dryness in the central Corn Belt. Correspondingly, while drought conditions eased over the northern areas, rapid expansion of drought and abnormal dryness was observed along the Ohio River Valley. During the next 7 days, widespread heavy rainfall (2-5 inches), partly associated with the remnants of Tropical Storm Imelda, is forecast to overspread Missouri, Iowa, and Illinois, with 1-3 inches favored across the Great Lakes region. Lighter accumulations are forecast south of the Ohio River, which may allow drought conditions to continue expanding in the short term. The CPC 8-14 day outlook indicates a similar distribution of precipitation, while the monthly and seasonal outlooks maintain equal chances for below-, near-, and above-median precipitation. Based on the short term forecasts, drought reduction is favored for eastern Iowa through Michigan and Ohio, while persistence is favored along and south of the Ohio River. Drought development is favored for parts of Kentucky, and while further expansion is possible early in the outlook period, the potential for soil moisture recharge later in the fall may limit the duration of drought conditions.

Forecast confidence is moderate for the Midwestern Region.

Drought depictions over the last month changed substantially across Texas, with small areas of improvement interspersed with widespread development and expansion across the central portions of the state. Eastern Texas had the most widespread degradation, with many regions north and west of Houston going from drought-free to severe drought (D2) in the last 4 weeks. Tropical Storm Imelda made landfall along the northeastern coast of Texas on 17 September, and the remnants of this tropical cyclone are expected to continue producing widespread heavy rainfall across eastern Texas and southeastern Oklahoma. Accumulations near or greater than 10 inches are possible in the vicinity of Houston. Due to this extreme near-term event, widespread immediate drought reduction is favored across eastern Texas, southeastern Oklahoma, and northern Louisiana. Across the remainder of the Southern Plains, climatological precipitation drops steadily over the next three months, limiting the window for improvement. The CPC 8-14 day outlook shows slightly enhanced chances for above-median rainfall across Texas, while the monthly and seasonal guidance maintain equal chances or even favor below-median precipitation. Given the lack of a clear wet signal in October, drought persistence is favored across the remainder of the Southern Plains, and enhanced chances for above-normal temperatures favor slight expansion of drought across south-central Texas. Elsewhere, drought development is possible across eastern Tennessee, due to the same factors discussed above for the Southeast Region.

Forecast confidence is high for eastern Texas and the lower Mississippi Valley, moderate for the Southern Plains, and low for the Tennessee Valley.

A north-south contrast was also observed across the Western Region, with above-normal precipitation observed across the northern tier and a very quiet Southwest Monsoon season. The abundant Northwest moisture ate away at drought conditions across Washington, Oregon, and the northern Rockies, while widespread drought development occurred across the Desert Southwest. Climatological precipitation ramps up across the Pacific Northwest during OND, while the monsoon season ends for the Southwest. Therefore, despite both the short and long term guidance favoring above-median precipitation for the Southwest, the chances for substantial improvements are limited. Drought persistence is the most likely outcome for most of the region, but short-term moisture across southern Arizona may yield some improvement. Across the Northwest, widespread heavy precipitation is favored in the short term, and a wet pattern is anticipated to persist through October. Therefore, continued drought improvement is favored. The seasonal outlook does indicate enhanced chances for below-median precipitation across Oregon, but the remaining D1 along the Willamette River is likely to be ameliorated early in the period.

Forecast confidence is high for the northern half of the Western Region, and moderate for the southern half.

Climatological precipitation decreases across Alaska during OND, but enhanced precipitation favored during October increases the chances for drought improvements along and east of the Kenai Peninsula. For Hawaii, OND falls before the wettest time of year, but model guidance strongly favors a wet pattern over the next several weeks. Therefore, drought reductions are the most likely outcome. Drought remains across southern Puerto Rico, with model guidance generally depicting suppressed Caribbean convection outside of any potential tropical cyclone activity. Therefore, drought persistence is indicated, but uncertainty is high as the hurricane season continues.

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

Forecaster: Adam Allgood

Next Seasonal Drought Outlook issued: October 17, 2019 at 8:30 AM EDT