Tools used in the U.S. Seasonal Drought Outlook (SDO) included the official Climate Prediction Center (CPC) temperature and precipitation outlooks for October 2015 and October – December (OND) 2015, various short- and medium-range forecasts and models such as the 5-day and 7-day precipitation totals forecast (QPFs) from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC extended-range forecasts (ERFs), the NAEFS precipitation outlooks, the soil moisture tools based on the Constructed Analog on Soil Moisture (CAS), dynamical models (CFSv2, NMME, IRI, IMME, and ECMWF), the 384-hour total precipitation forecasts from several runs of the GFS, the four-month Palmer drought termination and amelioration probabilities, October – December climatology for each month and the season as a whole, and initial conditions. An El Nino (ENSO) Advisory remains in effect, with the September 10, 2015 ENSO Diagnostic Discussion indicating a 95 percent chance of El Nino conditions continuing through Northern Hemisphere winter 2015-16. Collectively, current oceanic and atmospheric conditions reflected a strong El Nino, according to the Diagnostic Discussion, and strong El Nino conditions are expected to continue for at least the next few months. In fact, for this time of year, most indicators classify the current El Nino as one of the 3 to 5 strongest on record (since 1950). Currently, the effects of El Nino on conditions in the United States are minimal, which is expected at this time of year; however, it will become increasingly influential as fall progresses into winter. Given the strength of the event, and the fact that the atmosphere is already responding where expected, El Nino correlations dominated forecast considerations, along with initial conditions. The official Long Lead Forecasts similarly gave a lot of weight to El Nino considerations.

The areas of moderate drought along the Northeast coast should continue through the end of December. Strong El Nino episodes generally bring drier than normal weather to the Northeast during the last 3 months of the year, although the correlation is not strong. Still, with no heavy precipitation (thus no improvement) expected during the last half of September, drought is expected to persist.
Forecast confidence in the Northeast is low.

In the Southeast, the Florida Peninsula is expecting heavy precipitation over the next 5 to 7 days, with central and southern parts anticipating 1.5 to 3.5 inches. Rainfall should be unremarkable in the rest of the region through the last half of September, but El Nino strongly favors above-normal precipitation throughout the region for the rest of the forecast period.. The October – December Precipitation Outlook favors above-normal amounts throughout the region, especially Peninsular Florida.
Forecast confidence for Southeast is high.

The small area of drought in southwestern Wisconsin should get a bit over an inch of precipitation in the next 7 days, with dry weather favored for the last week of September. Over  the ensuing 3 months, the October – December Precipitation Outlook favors neither unusually dry nor unusually wet conditions, and strong El Nino episodes very slightly favor wet weather more than dry; Given it is also getting colder, it seems more likely than not that this area of moderate drought will be removed by the end of September.
Forecast confidence in southwest Wisconsin is low.

In the central and southern Great Plains and the lower Mississippi Valley, up to 2 inches of rain may fall on Oklahoma in the next week, but in general, precipitation through the end of September is expected to be near or below normal. El Nino episodes strongly correlate to abnormally wet conditions during October – December, and the official 3-month Outlook reflects this. Consequently, it seems unlikely that drought will persist unchanged until the end of the year, thus improvement or removal is anticipated.
Forecast confidence in the Plains and lower Mississippi Valley is high.

From the northern Rockies through the Pacific Northwest and southward into northern California, the next week is expected to be generally dry except for some moderate precipitation in westernmost Washington. The odds for above-normal precipitation increase during the last week of September, but El Nino favors below-normal precipitation across this region during the ensuing 3 months as the climatological wet season gets underway. Any surplus precipitation in the next few weeks is expected to be overwhelmed by drier than normal weather thereafter, resulting in a forecast of persistence. In addition, drought is expected to expand into the region from northeast Nevada through adjacent Idaho, northwestern Wyoming, and much of Montana, where El Nino and the October – December Outlook also favor unusually dry conditions the last quarter of the year 
Forecast confidence from the northern Rockies to the Pacific Northwest and northern California is high.

El Nino conditions strongly favor above-normal precipitation across Arizona, southern Nevada, and the southern half of Utah, as does the October – December Outlook. There is some indication that late September will be wetter than normal as well. Thus improvement is expected by the end of the year.
Forecast confidence in Arizona, southern Nevada, and the southern half of Utah is high.

Heavy precipitation is also significantly favored across southern California as the wet season gets underway. Drought conditions are not as serious in southeastern California as they are in most of the rest of the state, so with indicators strongly pointing toward enhanced precipitation during October – December, improvement and/or removal is expected there. Coastal southern California is experiencing extreme drought, but the expected wetness should be enough to bring at least limited improvement by the end of the year. Los Angeles, CA recorded more rain on September 15 (1.8 inches) than is normal during the entire dry half of the year (May – October). All signs point toward improvement, although a little less enthusiastically near the coast.
Forecast confidence in southern California is high.

Central California and western Nevada is a tricky forecast. Although the official October – December Outlook is non-committal, strong El Nino episodes tend to bring heavy precipitation farther north than lesser events do, and the stronger the episode, the better the chance for enhanced October – December precipitation. On the other hand, antecedent conditions feature an entrenched drought that has deepened over the course of 4 years, and one or even a few heavy precipitation events may not be enough to substantially change things early in the wet season. The odds seem best for some improvement along the immediate coast, where precipitation increases most readily in response to stronger El Nino episodes, and where precipitation is climatologically heavier. Farther east, from the interior valley of central California into west-central Nevada, the drought is exceptional and well-entrenched, and considering only the last one-half to one-third of the period is part of the typical wet season, precipitation would have to be markedly enhanced to bring any significant improvement, so persistence is forecast there.
Forecast confidence in central California and west-central Nevada is moderate.

Both Puerto Rico and Hawaii are entering their dry seasons as the year winds down, reducing the odds for drought-changing amounts of precipitation, even considering El Nino tends to favor above-normal dry-season rainfall in Puerto Rico. Drought persistence is favored.
Forecast confidence in both Hawaii and Puerto Rico is moderate.

Drought has improved significantly with soaking rains affecting the Alaska Panhandle. Moderate drought areas farther to the north, across central and interior southeast Alaska, have not been as wet and have responded more slowly, but a continuation of gradual improvement is expected.
Forecast confidence in Alaska is moderate.

Forecaster: Rich Tinker			

Next Seasonal Outlook issued: October 15, 2015 at 8:30 AM EDT