January 2015

Outlook Graphic: PNG   PDF 

Latest Monthly Assessment - During the past 2 weeks since the release of the latest Seasonal Drought Outlook (Dec. 18), drought improvement occurred in north-central California, parts of the Northwest, along portions of the western Gulf Coast, and in most of New England and the Southeast. The recent wetness in the latter region abruptly ended a steady expansion of dryness and drought prior to late December. Drought mostly persisted in the remainder of the West and Southwest, the northern and southern Plains, Tennessee and lower Mississippi Valleys, in parts of the mid-Atlantic, and in Hawaii and Puerto Rico.

During early January, the recent pattern of above-normal precipitation for the Gulf Coast and Southeast is expected to continue, allowing for additional improvement or removal of drought in the extreme southern Great Plains, the lower Mississippi Valley, and central Gulf Coast. Additionally, favorable odds of above-median precipitation in week 1 and 2 outlooks across the eastern third of the Nation will not only prevent any deterioration of lingering abnormal dryness, but may also remove the short-term D0 by the end of the month. In the central and northern Plains, however, the winter months are climatologically dry, the ground is usually frozen until the spring (especially in northern locales), and there are conflicting or no clear signals over the upcoming month, hence persistence.

In the Southwest, cold and snowy weather will usher 2015 in, increasing currently low snow packs in Arizona, southern Utah, western New Mexico, and southern Colorado. After this storm passes, however, drier and milder conditions are expected during week 1 and 2 outlooks, providing no help for improvement of drought. Although the January precipitation outlook tilts the odds toward above-median totals across the Southwest, the expected quiet first half of the month (after the Jan. 1 storm), along with relatively low January normals for most of the region, would not be enough for any drought improvement by the end of the month.

In the West, drought is expected to persist where it exists across the Intermountain West and Pacific Coast States, including California. Unfortunately, the wet and mild weather that impacted north-central California during the first half of December was replaced by colder and drier weather late in the month. This drier weather pattern is expected to continue into early January, and with the three winter months (Dec-Jan-Feb) climatologically the wettest in California, any extended period with minimal precipitation quickly accumulates deficits. Considering the entrenched multi-year nature of the drought in California, recent Drought Monitor improvements (D4 to D3) in north-central sections, and somewhat decreased odds for above-median January precipitation in northern California in the updated monthly outlook, conditions are not expected to improve substantially by the end of January. However, with a weak El Nino event expected to occur late this winter into the spring bringing favorable odds for above-median monthly and seasonal precipitation across southern California, the Seasonal Drought Outlook (JFM'15) indicated that some improvement is likely by the end of March. But even if this happens, 3 straight years of drought and large accumulated deficits will most-likely take several years of above normal winter precipitation to completely eradicate the drought, especially with respect to hydrologic conditions.

The odds favor drier than normal weather in Hawaii during January, and for the winter as a whole. Climatologically, rainfall is highest during the winter months in Maui and Molokai (where small D1 areas currently exist). But with recent, widespread, moderate to heavy showers in late December, these rains should more than offset any predicted subnormal January precipitation, thus drought should persist (and not expand) by the end of January. There is currently no drought (and none forecast) in Alaska and Puerto Rico.

Tools used in the U.S. Monthly Drought Outlook (MDO) included the official Climate Prediction Center (CPC) updated temperature and precipitation outlooks for January 2015, various short- and medium-range forecasts and models such as the 7-day precipitation totals from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC forecasts, week 3 and 4 experimental outlooks, the NAEFS precipitation outlooks, dynamical models (CFSv2), the 384-hour total precipitation forecasts from several runs of the GFS, climatology, the latest official Drought Monitor analysis (valid on December 30), observed precipitation during the previous month, and initial conditions.

A wet late December resulted in the elimination of drought across Georgia and a decrease in drought coverage across much of Alabama, the Florida Panhandle, Louisiana, and Mississippi. However, drought lingered along the central Gulf Coast. During the next week, WPC indicates a widespread area of 1 to 3 inches of rainfall for the areas that remain in drought. This wet start to the New Year, plus favorable odds for above-median precipitation in the 6-10 and 8-14 day and updated monthly forecasts, indicates removal of short-term drought along the Gulf Coast.
Confidence in the forecast along the Gulf Coast is high.

Short-term drought persists across most of Arkansas, and unlike the remainder of the Southeast, this area received below-normal rainfall during the past 30 days. Beneficial rains are expected to start in early January and potentially bring some improvement to drought conditions. Since the Arkansas drought is characterized as moderate (D1) on the U.S. Drought Monitor, removal is forecast. The most recent signals among precipitation tools beyond Week-1 have better consolidated, but the recent dry spell slightly reduces forecast confidence as compared to the rest of the Southeast.
Confidence in the forecast for Arkansas is moderate.

Despite light to moderate precipitation to begin the New Year and a slight tilt in the odds towards above-median precipitation forecast by the CPC January outlook, a relatively dry climatology and subnormal 60- and 90-day precipitation favors persistence for most of the central and southern Plains. Similar to the previous monthly outlook valid for December 2014, the greatest uncertainty is how much if any drought improvement or removal occurs across Texas. Higher precipitation totals (1 inch or more) and a slightly wetter climatology during January favor improvement or removal for the drought areas in the eastern half of Texas.
Confidence in the forecast for the central/southern Plains ranges from high on persistence to low on the areas of improvement/removal.

A small area of drought (D1) is depicted on the U.S. Drought Monitor map for northeast South Dakota. The dry climatology and generally frozen ground during the winter favors persistence through the end of January.
Confidence in the forecast for South Dakota is high.

Drought conditions across the southern Rockies, Great Basin, Southwest, and the West Coast are most likely to persist on a broad scale. Although moderate to heavy snow is expected in the short-term across parts of the Southwest and southern Rockies, much below-normal snow water equivalent values (50 percent of less as of December 30) favors persistence for these areas. Typically, 14 to 20 percent of the annual precipitation occurs during January across California. This relatively wet climatology argues for improvement for California; however, persistence is forecast because of (a) the entrenched, multi-year nature of the drought in California and (b) a likely dry start to the month. Any improvement that is realized by the end of January is expected to be small in scale which is unpredictable a month in advance.
Confidence in the forecast across the West is moderate.

Monthly precipitation tools for January, along with CFS precipitation forecasts during the next two weeks, indicate enhanced odds for below-median precipitation across Hawaii. But with widespread moderate to heavy rains around Christmas, drought expansion has been tempered. Therefore, the small areas of drought that exists should persist.
Confidence in the forecast for Hawaii is high.