Tools used in the U.S. Seasonal Drought Outlook (SDO) included the official Climate Prediction Center (CPC) temperature and precipitation outlooks for November through January 2016-17 (NDJ), 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 NDJ season, and initial conditions. There is now about a 70 percent chance of a La Nina developing during the Northern Hemisphere fall 2016, which is slightly favored to persist (about 55 percent) during winter 2016-17.

According to the Advanced Hydrologic Prediction Service (AHPS), the Northeast and the eastern Great Lakes region have reported 30-day precipitation deficits on the order of 1-5 inches. The U.S. Drought Monitor (USDM) continues to depict moderate to extreme drought (categories D1 to D3) across this region. The probability of experiencing significant drought amelioration increases during the cooler half of the year, especially with the climatological increase of mid-latitude storm activity associated with an energized polar jet stream. Lake temperatures across the eastern Great Lakes are considerably above-average going into the NDJ season, which favors increased precipitation amounts to areas downwind of the Great Lakes. The drought outlook for this part of the country is quite uncertain, because once a drought is firmly established, it is often difficult to dislodge it, hence the forecast conflict in this region. Normally, cold season storm activity would be enough to erase any drought across the Northeast and the Great Lakes region, but this idea has very little model support. For example, various climate models such as the calibrated North American Multi-Model Ensemble (NMME), the Climate Forecast System (CFS), and the International Multi-Model Ensemble (IMME) predict very weak precipitation anomalies across the Northeast during NDJ. In the absence of strong model indications to the contrary, it was decided to leave the region from northern New Jersey and Long Island through southern and central New England as likely to experience drought persistence. The remainder of the Northeast drought region, however, has more support for improvement or removal of drought, based on such factors as WPC's 7-day precipitation total (approaching 5 inches), various climate model output, and the idea of unusually warm water present in the eastern Great Lakes region. CPC's November and NDJ precipitation outlooks express this uncertainty with the prediction of Equal Chances (EC) in this area.

Longer-term drought (in excess of 6-months) continues to dominate the interior southeastern United States. This region encompasses much of Mississippi, Alabama, southern and eastern Tennessee, the northwestern two-thirds of Georgia, and far western portions of the Carolinas. In the past 30-days, rainfall deficits generally range from 1-4 inches, with a few localized areas reporting even greater deficits. During the past 60-days, dryness and drought has developed and expanded across the Lower Mississippi Valley. Precipitation deficits have mounted rapidly in this latter area, ranging from 4-5 inches in only the latest 30-days. Though precipitation forecasts out through two weeks generally favor a "front-loaded" wet period across the Lower Mississippi Valley, the primary signal from CPC's longer range outlooks (30-days and 90-days) favors elevated odds of below-median precipitation. The NDJ forecast depicts a 50-percent or greater chance of below-median precipitation from south-central Texas eastward across portions of the Lower Mississippi Valley to the Florida Panhandle. Therefore, drought is anticipated to persist or worsen across much of the region, and drought is expected to develop across eastern and southern portions of Texas, the Lower Mississippi Valley, extreme southern Alabama, southwestern and south-central Georgia, and the central Florida Panhandle. In stark contrast, however, areas closer to the Southern Atlantic coast were inundated with excessive precipitation and flash flooding when former Hurricane Matthew traversed the region almost two weeks ago. Drought removal is favored across far northern portions of the drought area, including eastern parts of Tennessee and Kentucky.
Forecast confidence for the Southeast is moderate to high, and confidence for the Lower Mississippi Valley is moderate.

The more localized areas of drought currently over the central and southern Great Plains are generally predicted to persist, despite the prediction of some precipitation within the next two weeks. The drier seasonal drought outlook is consistent with CPC's precipitation outlooks for November and NDJ, which broadbrush most of the southern CONUS with enhanced odds of below-median precipitation. This is also consistent with La Nina composites for NDJ, though the official ENSO forecast calls for a weak La Nina. Drought development is likely across eastern and southern portions of Texas, as well as over parts of the southern High Plains. Despite this being October, this latter region is experiencing flash drought conditions with the recent heat and wind.
Forecast confidence for the central and southern Plains is moderate.

During the past 30-days, the northern High Plains have received significant precipitation surpluses (widespread coverage of 2-8 inches). Above-median precipitation is favored across this region with the November and NDJ precipitation outlooks from CPC. The seasonal drought outlook therefore favors improvement and removal of drought.
Forecast confidence for the northern Plains is moderate.

Status quo is generally expected across the Southwest during NDJ. Traditionally, La Nina events tend to favor continuing dryness across this region. CPC's 30-day and 90-day precipitation outlooks predict increased odds of below-median precipitation across the Southwest, with the 90-day outlook also going with significant coverage of EC across Utah and Colorado. Another consideration is moisture associated with eastern Pacific tropical cyclones entering the region from the south. This is always a wildcard in October, though at this time it does not look like enough precipitation will affect the Southwest to have a significant impact on the current drought depiction.
Forecast confidence for the Southwest is moderate.

For the Pacific Northwest and northern California, the rainy season has gotten off to a good start. Much of Washington state, western Oregon, and northern California have received anywhere from 2 to 6 times their normal precipitation so far this season. In the upcoming 7-day period, WPC predicts precipitation amounts of 5-6 inches (liquid equivalent) are possible throughout the coastal ranges and Cascades of the Pacific Northwest, and far northwestern California. Enhanced odds for above-median precipitation are predicted for nearly all of this area during Week-2. CPC's monthly outlook for November favors above-median precipitation across the Northwest, below-median precipitation across the southern half of California, and EC in-between. The seasonal outlook for NDJ, however, is less confident, with EC being the dominant forecast across the region. There are considerable differences in model opinion between climate models regarding the NDJ precipitation forecast for the Northwest and northern California. The probabilistic NMME precipitation forecast depicts a slight tilt towards wetness across portions of the Pacific Northwest, and a slight tilt towards dryness across far southern California, with the CFS model being slightly more confident on these tilts. Interestingly, the IMME favors dryness across California and southwestern Oregon, with little to no useable signal across the remainder of the Northwest. Assuming a weak La Nina is able to set up this autumn and winter, the odds would be in favor of at least some improvement (and/or removal) across the Northwest and approximately the northern third of California. A month from now, the progress of the developing La Nina should be much clearer, and if justified, improvement and/or removal can be extended farther south in California. 
Forecast confidence is moderate for the Pacific Northwest and California.

The outlook for the Hawaiian archipelago favors abnormally wet conditions, which is fairly consistent with cold-season La Nina episodes. Therefore, improvement and/or removal of current drought conditions is forecast across the islands.
Forecast confidence for Hawaii is moderate.

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

Forecaster: Anthony Artusa

Next Seasonal Drought Outlook issued: November 17, 2016 at 8:30 AM EDT