Near- to above-normal precipitation again prevailed from the High Plains to the East Coast, leaving the eastern and central parts of the Nation nearly drought-free. Here, moderate drought is restricted to southeastern Florida, northern North Dakota, a small part of northeast Oklahoma and adjacent Missouri, and the central Texas Panhandle.
Farther west, precipitation was sufficient to keep most of Idaho, Montana, and Wyoming out of drought as well. As of mid-December, 37 states were at least 95 percent drought-free, and only 7 states were more than one-third drought covered. But in stark contrast to the rest of the country, these states (The Four Corners States, Nevada, California, and Oregon) still have extensive drought coverage (over 70 percent in 6 states), and a large swath centered near the Four Corners remains locked in an entrenched, long-term drought. Extreme to exceptional drought blankets much of this region, as it has since mid- to late-spring in many areas.
The only other area of drought covers southeast Alaska, usually one of the wettest areas in the country. Through mid-December, 2018 brought just over 100 inches of precipitation to Ketchikan in the far southern Panhandle. This is more than 3 feet below normal, and 2018 will end up about the eighth driest of the 105 years on record there.
In accord with the developing El Niño development, above-normal precipitation (and drought removal) is expected in southern Florida. Farther west, the patches of drought in the Plains are expected to persist. The three-month outlook favors drier than normal weather in the Pacific Northwest and northern California through March, so persistence is forecast here despite heavy late-December precipitation expected in western Oregon.
Drought improvement and removal is expected in the rest of California, most of Nevada and Utah, the west half of Arizona, and western Colorado, though with low confidence from the Great Basin westward. Farther east, across the entrenched long-term drought near the Four Corners to the High Plains, drought is expected to persist despite a three-month forecast favoring above-normal precipitation.
January-March is a drier time of year here, and given the extreme and long-term nature of the drought here, wetter-than-normal weather during a drier time of year probably won’t be enough to bring notable improvement. Southeast Alaska should also remain in drought; it’s unlikely that enough precipitation will fall to boost streamflows and end the threat to hydroelectric power production.
Forecast confidence in the Western Region is moderate in the Pacific Northwest and northern California, low in most of California and Nevada, and moderate in most of the Four Corners States.
- For much of the Western Region, either neutral or contradictory indicators result in low-confidence forecasts for much of the reason.
- Subnormal precipitation is expected for JFM in the Pacific Northwest, adjacent Idaho, and northern California, which should leave drought conditions unchanged or slightly worse by the end of March.
- Severe to extreme drought covers much of Oregon and adjacent California, but some temporary relief is expected west of the Cascades by the day after Christmas. A strong storm is expected to drop between 3 and 7 inches of precipitation near the coast and on the western slopes of the Cascades.
- This reduces confidence in the persistence forecast, but a preponderance of models and statistical forecasts point toward a dry JFM, so the forecasts leans in that direction, expecting that any relief shown on the Drought Monitor will be temporary as moisture deficits slowly accumulate during the enuing 3 months.
- Marginal improvement is forecast farther south across the rest of California, Nevada, and northwestern Utah. 6-month precipitation is within 2 inches of normal, with a few patches showing slightly drier conditions.
- Most areas are in moderate drought, with more severe conditions across southernmost California and in northwestern Utah and adjacent Nevada. The JFM forecast leans neither dry nor wet, but this is a wet time of the year across California, where 45 to 65 percent of annual precipitation typically falls during JFM.
- It’s a neutral to marginally wet season farther east, with JFM bringing 30 to 40 percent of annual precipitation to most of Nevada, and only 20 to 30 percent to northwestern Utah. Given the lack of useful guidance, antecedent conditions of nominal moderate drought, that it’s about the wettest time of year in California and (to a lesser extent) Nevada, and that Utah is near an area with enhanced chances for an abnormally wet JFM…improvement is forecast, though without much enthusiasm or confidence.
- Improvement or removal is forecast with somewhat more confidence across most of Utah, the western half of Arizona, and much of western Colorado. Most of this area is in moderate to severe drought, and while JFM isn’t particularly wet or dry relative to other times of the year, the 3-Month JFM outlook shows enhanced chances of above-normal precipitation, which should be enough to improve conditions.
- The forecast for drought areas in eastern Arizona, New Mexico, southern and eastern Colorado, and adjacent Utah is complicated by robust but contradictory indicators.
- In large part driven by the expected El Niño development, the 3-Month outlook favors above-normal precipitation across the area, with the greatest chances noted in central and eastern sections of the longstanding D3-D4 area centered near the Four Corners region, and points east.
- That would argue for improvement, but 2 factors work against it. First, the deep and long-term nature of the drought here means it’ll take an extended period of persistent and above-normal precipitation to noticeably improve the drought. Second, this is a dry time of year for the region, with JFM typically brining 5 to 15 percent of annual rainfall to central and eastern New Mexico, and 15 to 20 percent in eastern Arizona and southwestern Colorado.
- In summary, a wetter-than-normal dry season is anticipated in a region where D3-D4 drought has been entrenched for months, which probably won’t be enough to bring noticeable, lasting improvement.
Forecast confidence in the Southern Region is moderate to high in and around northeastern Oklahoma, and low to moderate in the Texas Panhandle.
- In the Southern Region, drought is restricted to 2 small patches. One in the middle of the Texas Panhandle, and one in northeastern Oklahoma and adjacent parts of Missouri and Arkansas.
- JFM is slightly drier than other times of the year in and around northeastern Oklahoma, and the 3-Month outlook favors neither above- nor below-normal precipitation. And despite its small size and D1 classification, dryness dates back many months, with much of the area 5 to locally 12 inches below normal precipitation for 2018.
- Considering these factors, persistence is the only logical forecast here.
- Things are much less clear in the central Texas Panhandle, where odds significantly favor above-normal precipitation in the 3-Month outlook. However, above-normal precipitation in JFM, when only 5 to 10 percent of annual precipitation is typically observed, isn’t likely to significantly boost the 50 to 75 percent of normal precipitation that’s fallen since January 2018, so persistence is also forecast here.
Forecast confidence for the High Plains Region is moderate in Colorado, and high in North Dakota.
- Outside the protracted drought affecting Colorado and a small slice of adjacent Wyoming (which was discussed in the Western Region summary), only part of northern North Dakota is in moderate drought. The last 30 to 60 days have had close to normal precipitation, but longer time scales dating back a year or more still show signficantly below normal precipitation.
- Since an average JFM brings only 5 to 10 percent of yearly precipitation, it’d take something climatologically extreme to take D1 off the map.
Forecast Confidence in the Midwest Region is moderate to high
- The only area of drought remaining in the Midwest Region is in the far southwestern corner of Missouri (discussed in the Southern Region summary), and drought development is not expected elsewhere.
Forecast confidence in the Southeast Region is moderate to high.
- In the Southeast Region, drought is restricted to southeastern Florida. It is a fairly dry time of year for the region, but normals year-round are more substantial than in the Plains (where JFM is also a drier time of year), and El Niño development would strongly favor above-normal JFM precipitation, as indicated in the 3-Month outlook. Thus drought removal is forecast.
Forecast Confidence in the Northeasst Region is high.
- There is no drought analyzed anywhere in the Northeast Region, and while some abnormal dryness is showing up along the northern tier, drought development is not expected, especially considering how cold it is normally in JFM.
Forecast confidence for Alaska, Hawaii, and Puerto Rico is moderate to high.
- Moderate to severe drought covers the southern half of the Alaska Panhandle, one of the wettest areas in the country climatologically.
- Ketchikan, in the far southern Panhandle, has measured just over 100 inches of precipitation for 2018 with a couple weeks remaining; however, this is more than 3 feet below normal, and 2018 will end up being about the eighth driest year since records began in 1914 (105 years).
- JFM is not particularly wet or dry compared to other times of the year, but normals progressively decline as the region heads toward its drier season (late spring to mid-summer). The 3-Month outlook favors a wet JFM, which would point toward improvement, but the 3-Month temperature outlook strongly favors a warmth, which would temper any improvement and likely keep streamflows unfavorably low, continuing the threat to hydroelectric power production. Snowpack could also be substantially squelched if the season is warm enough.
- In sum, the indicators seem to tilt toward a persistence forecast, though the enhanced above-normal JFM precipitation chances reduces confidence.
- There is no drought in Hawaii or Puerto Rico at this time, and none is forecast to develop.