Tools used in the U.S. Seasonal Drought Outlook (SDO) included the official Climate Prediction Center (CPC) temperature and precipitation outlooks for March through May 2017 (MAM), 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, the four-month Palmer drought termination and amelioration probabilities, climatology for the MAM season, and initial conditions.
 
Major drought reduction continued across California during the past month, with 1 to 3 class improvements across the southern two-thirds of California, while the northern third of the state is drought-free. According to the U.S. Drought Monitor, valid on February 7, 47 percent of California is designated with long-term drought, and less than 1 percent designated in the extreme (D3) to exceptional (D4) categories. The coverage of California drought is at its lowest since January 2012. According to preliminary information from the National Centers for Environmental Information (NCEI), California had its 6th wettest January during the 123-year period of record.  As of February 14, snow water content is around 200 percent of normal throughout the Sierra Mountains. Data from the California Department of Water Resources indicates that many of the larger reservoirs throughout the state are running at or above their historical average. However, the Perris reservoir in southern California is below 50 percent of its historical average. The Cachuma Reservoir in Santa Barbara County is currently at 15.5 percent capacity as of February 9. Another round of heavy precipitation (rain and high-elevation snow) is likely across California during the next week. The WPC 7-day precipitation forecast indicates more than 5 inches (liquid equivalent) across the favored terrain areas of southern California with 1 to 3 inches of precipitation extending as far inland as southern Nevada. Given the wet winter so far and the likelihood of heavy precipitation during the next week, continued improvement or removal of drought is expected across most of the long-term drought areas of California and Nevada. It should be noted that hydrological impacts such as ground water may not completely recover due to the longevity of the drought.

Forecast confidence is high for California and Nevada but low for the persistence across the desert Southwest. 

A couple of small long-term drought areas exist across western Montana and eastern Oregon. Snow water content values are currently running at or above-average throughout the Pacific Northwest, northern Great Basin, and northern Rockies. Based on the favorable snowpack and the CPC seasonal outlook calling for an increased chance of above-median precipitation, removal is most likely across the lingering drought areas of eastern Oregon and western Montana.

Forecast confidence is moderate for eastern Oregon and western Montana.

Long-term drought continues across the high Plains of eastern Wyoming and western South Dakota. A slight tilt the odds for above-median precipitation is forecast for this region from March through May. 30 to 40 percent of annual precipitation typically occurs during this three month period. Based on these factors, drought removal is forecast.

Forecast confidence is moderate for the northern high Plains.

During the past three months, long-term drought expanded slightly across the central and southern high Plains.  The early part of the outlook period, through the end of March, is a relatively dry time of year for these areas. Since this region typically becomes wetter only during May, persistence is most likely on a broad scale from the high Plains of eastern Colorado south to New Mexico. 

Forecast confidence is low for the central and southern high Plains.

Moderate (D1) to extreme (D3) drought continues across the southern Great Plains and parts of Arkansas and Missouri. During the past 48 hours, a widespread area of 1 to 3 inches of beneficial rainfall occurred across the southern two-thirds of Oklahoma. This recent rainfall is expected to prompt slight improvement to the drought across Oklahoma in next week’s USDM. Elsewhere, the improvement and removal of drought forecast across Arkansas, Missouri, and Oklahoma is based largely on climatology as April and May become increasingly wet.

Forecast confidence is moderate for Arkansas, Missouri, and central/eastern Oklahoma.

Moderate drought recently developed along the middle Gulf Coast of Texas. Since the WPC 7-day precipitation forecast calls for several inches of rainfall over this region, this drought is expected to be short-lived. Meanwhile, drought is expected to persist and potentially expand slightly across the lower Rio Grande Valley where medium to extended range forecasts are drier and signals are weak beyond these time scales. 

Forecast confidence is high for the middle Gulf Coast of Texas and low for the lower Rio Grande Valley.

Long-term drought persists across the southern Appalachians and Tennessee Valley with northeast Georgia suffering from extreme drought. March and April are two of the wetter months of the year across these areas. Precipitation signals among tools at the extended range are weak across the Southeast, while spread is large among the climate models. Although improvement or removal of drought is forecast for the southern Appalachians and Tennessee Valley based on climatology, confidence is low. It should be noted that the CPC seasonal outlooks calls for enhanced odds for above normal temperatures for March through May. Abnormal warmth could offset any beneficial rainfall, which also limits forecast confidence.

Forecast confidence is low for the southern Appalachians and Tennessee Valley.

A lack of winter precipitation led to an expansion of abnormal dryness and moderate drought across the mid-Atlantic. Soil moisture currently ranks in the lowest 10th percentile across the Piedmont of Maryland and northern Virginia. The mid-Atlantic including eastern North Carolina is primed for additional expansion of drought in the next few weeks. Except for the 7-day forecast of little to no precipitation, precipitation tools offer weak or differing signals for this region. The latest deterministic GFS model runs on February 15 indicate a wetter pattern by the beginning of March. Removal of moderate drought is forecast for the mid-Atlantic, albeit with low confidence, since there is no strong support for a protracted drought through the end of May. This region will be closely monitored for the monthly outlook released on February 28.

Forecast confidence is low for the mid-Atlantic.

Precipitation amounts have varied from New Jersey north to New England during the past month, but drought generally remained steady or improved by 1 category. Given the favorable time of year for recharge, continued improvement or removal of drought is most likely for the Northeast. However, improvement to long-term impacts such as ground water across parts of the Northeast is uncertain.

Forecast confidence is low for the Northeast.

Moderate drought was introduced on the USDM, valid on February 14, across southern parts of the Florida peninsula. Much of the Florida peninsula received less than 50 percent of its normal precipitation during the past 90 days and above-normal temperatures prevailed throughout much of the winter. Since the convective season typically begins late in May across the southern Florida peninsula, persistence and development is forecast for south Florida. 

Forecast confidence is moderate for south Florida.

Very small areas of moderate drought remain along the leeward sides of Kauai, Maui, and the Big Island of Hawaii. Since late February through April is a relatively wet time of year across Hawaii, drought removal is forecast. Although abnormal dryness currently exists across southeast mainland Alaska, low confidence precludes an introduction of development to this region. Drought is also not expected to develop across Puerto Rico through the end of May.

Forecast confidence is moderate for Hawaii, Alaska, and Puerto Rico.

Forecaster: Brad Pugh

Next Seasonal Outlook issued: March 16, 2017 at 8:30 AM EDT