With the strong El Niño event underway and expected to continue through the forecast period, our Outlook is based primarily on conditions typically observed during these events, with some consideration for longer-term trends and model output, all of which is reflected in the October -November-December 3-Month Outlooks.
Impacts on the drought include likely persistence for the small areas in the Northeast and the broad area of drought in the northwest and much of California, with some development expected in concert with the favored dryness in the northern Rockies.
Along the central and southern California coast, and in a broad swath from the Southwest to the Southeast, abundant precipitation, especially later in the period, is expected to bring widespread improvement.
Click Image to Enlarge
As this is a relatively dry time of year, drought is most likely to persist where it exists in Puerto Rico and Hawaii while additional slow relief is expected in Alaska.
Forecast confidence in southern California is high.
- Heavy precipitation is 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 central California and west-central Nevada is moderate.
- Central California and western Nevada is a tricky forecast. Although the official October – December Outlook is non-committal, strong El Niño 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 Niño 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 from the northern Rockies to the Pacific Northwest and northern California 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 Niño 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 Niño and the October – December Outlook also favor unusually dry conditions the last quarter of the year
Forecast confidence in the Plains and lower Mississippi Valley is high.
- 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 Niño 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 for Southeast is high.
- 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 Niño 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 in Arizona, southern Nevada, and the southern half of Utah is high.
- El Niño 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 the Northeast is low.
- The areas of moderate drought along the Northeast coast should continue through the end of December.
- Strong El Niño 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 southwest Wisconsin is low.
- 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 Niño 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 both Hawaii and Puerto Rico 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 Niño tends to favor above-normal dry-season rainfall in Puerto Rico.
- Drought persistence is favored.
Forecast confidence in Alaska 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.
