Tools used in the U.S. Seasonal Drought Outlook (SDO) included the official Climate Prediction Center (CPC) temperature and precipitation outlooks for October through December 2016 (OND), 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 (CFSv2, NMME, IRI, IMME, and ECMWF), the 384-hour total precipitation forecasts from several runs of the GFS, weeks 3-4 experimental temperature and precipitation outlooks, the four-month Palmer drought termination and amelioration probabilities, climatology for the OND season, and initial conditions. ENSO-neutral conditions are now favored (55-60%) this fall and winter as the most recent model consensus has backed away from a La Nina Watch, although OND forecasts still have some La Nina winter impacts, albeit diminished.

Spotty rainfall, much above-average temperatures (3 to 6 degs F above-normal), and growing negative impacts resulted in drought expansion and intensification across coastal New England, western New York, and New Jersey during the past 30 days. Since April 1, deficits of 8-12 inches have accumulated in southern New Hampshire, most of Massachusetts, and central Connecticut. Although the fall months see a reduction in temperatures and evapotranspiration which is favorable for drought recovery, the long term precipitation deficits and impacts, tilted odds toward above normal OND temperatures, and no obvious signal for wetness among the precipitation tools (EC), persistence is the best bet for the ongoing drought areas of New England, New York, New Jersey, and Pennsylvania. In addition, short-term drought development remains a concern during the remainder of September and into October across the mid-Atlantic where D0 has been recently added, but without a strong precipitation signal (EC) plus surpluses at 60 days and longer, no development was added. Farther west (eastern Great Lakes region), drought is more likely to be removed (current areas of D1) across eastern Michigan and northern Ohio due to the shorter duration of the drought and recent wetness and drought improvement.  Forecast confidence is low across the Northeast due to conflicting factors previously mentioned in this regional summary (e.g. lowered temperatures and evapotranspiration rates, weak precipitation tool signals, long-term rainfall deficits and hydrologic impacts), plus the possibility of autumn Nor'easters or tropical systems that can bring quick recovery.

Forecast confidence is low for the Northeast, and moderate across eastern Michigan and northern Ohio.

Since mid-August, unseasonable warmth (temperatures averaging 2 to 4 degs F above-normal) and hit and miss showers in the interior sections of the Southeast led to drought persistence or intensification in parts of Alabama, Georgia, and the southern Appalachians. However, more widespread and heavier precipitation, including rains associated with minimal Hurricane Hermine that soaked the eastern Gulf and southern Atlantic Coasts, provided some relief to the western, northern, and eastern edges of the drought area. The worst drought areas were located in northeastern Alabama and northern Georgia where areas of D3 persisted in the latest U.S. Drought Monitor. Unfortunately, the CPC OND outlooks favor below-median precipitation and above-normal temperatures (La Nina like anomalies) for the interior Southeast, which also extended westward into the southern High Plains, northward into Virginia, and eastward to the southern Atlantic Coast. Given the persistence of the drought, a dry and warm signal in the seasonal precipitation tools, a relatively dry October and November climatology (December is wetter), and recent (past 30-days) dryness and warmth from the central Gulf northeastward into the mid-Atlantic, drought persistence and development is forecast for most of the interior Southeast, southern Appalachians, western Carolinas, and southern Virginia.

Forecast confidence for the Southeast is moderate.

Small areas of short-term moderate (D1) to severe (D2) drought are depicted on the Sep. 13 U.S. Drought Monitor in central Oklahoma, north-central and extreme southern Texas, and eastern New Mexico. A forecast for removal of these small drought areas is based on rainfall expected during the remainder of September. The 7-day QPF from WPC indicated a broad area of 2-3 inches of rain from southwest Texas northeastward into southwest Missouri. Both the 6-10 and 8-14 day ERFs have favorable odds of above-median precipitation, as does the experimental weeks 3-4. With expected rainfall and increased cloud cover, seasonable temperatures are also favored during the remainder of September. The OND precipitation outlook, however, tilts the odds toward sub-median precipitation across the southern Plains, possibly causing dryness later in the period and decreasing the confidence in this forecast.

Forecast confidence for the southern Plains is moderate.

The northern and central Plains are currently designated with moderate (D1) to extreme (D3) drought, with the most widespread and severe drought centered in the north-central High Plains (western SD, northeastern WY, southeast MT). Small areas of D1 were also located in central Colorado and south-central Nebraska. Recent wetness out to 60-days has provided some reduction in drought in the north-central High Plains while short-term dryness has developed in Colorado and Nebraska. Although the short and extended range forecasts favored sub-median precipitation, the CPC monthly precipitation outlook enhances the chances for above-median rainfall in Nebraska, while the seasonal precipitation outlook depicts a slight tilt in the odds for above-median precipitation across the northern Rockies and High Plains. Based upon the monthly and seasonal precipitation outlooks, decreasing temperatures and evapotranspiration during the fall, and recent short-term wetness in the north-central High Plains, improvement or removal is forecast. However, forecast confidence is tempered since October-December are a rather dry time of year in the High Plains.
 
Forecast confidence for the northern and central Plains is low to moderate.

Recent rains from Hurricane Newton (southeastern AZ and western NM) and an occasionally robust Southwest monsoon has brought surplus to locally excessive rains to eastern sections of the Southwest. Recent USDM improvement have been made to drought areas of southeastern Arizona, southern Colorado, most of New Mexico, and western Texas. This short-term wetness, precipitation expected during the rest of September, and a somewhat wet but declining climatology through September favors removal of small D1 areas in eastern New Mexico and west Texas. In central Colorado, a slight tilt toward above-median October precipitation plus some wet seasonal precipitation outlooks warrant D1 removal there by the end of 2016. Farther west, conditions have been drier, the precipitation climatology rapidly drops during October and November (but rebounds during December), and the signal for precipitation is either dry or neutral (EC) in the short, medium, and long-term, thus persistence is forecast.
 
Forecast confidence for the Southwest is moderate.

During the past month, drought coverage and intensity remained nearly steady across the West, with development or intensification limited to parts of the eastern Great Basin, north-central Rockies, and coastal Washington as impacts from the early summer heat and early spring snow melt runoff were felt. With October still climatologically dry in much of California and the western Great Basin (although November and December get progressively wetter), the long-term duration and intensity of the drought, and no signal toward OND precipitation, persistence is a reasonable forecast. In contrast, removal is forecast for the small short-term D1 areas along coastal Oregon and Washington as this area typically becomes quite wet during November and December. In the northern Rockies (as mentioned in the central and northern Plains summary), a tilt toward above-median OND precipitation plus increasing climatology should provide some improvement by the end of December. A limiting factor for improvement, however, is the long-term nature of the drought which may require several more months with surplus precipitation.

Forecast confidence is moderate to high for California, western Great Basin, and the Northwest, low to moderate for the northern Rockies.

During the past El Nino, drought coverage peaked at nearly 80 percent of the Hawaiian Islands in early April. Since that time, that coverage decreased and is currently less than 5 percent as of Sep. 6. With moderate to heavy showers associated with moisture from Hurricanes Madeline (went south of islands) and Lester (went east of islands), plus above-median rainfall forecast by CPC's October and OND outlooks, the continued removal or improvement of drought on the leeward sides of Kauai, Molokai, Lanai, Maui, and Kahoolawe is expected.

Forecast confidence for Hawaii is moderate to high.

Only a small area of moderate drought (less than 5 percent coverage) lingers in south-central Puerto Rico. Based on a relatively wet September and October climatology, removal of this drought area is likely.

Forecast confidence for Puerto Rico is high.

Forecaster: David Miskus

Next Seasonal Drought Outlook issued: October 20, 2016 at 8:30 AM EDT