Tools used in the U.S. Monthly Drought Outlook (MDO) included the official Climate Prediction Center (CPC) updated temperature and precipitation outlooks for February 2016, 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 Extended-Range Forecasts (ERFs), Weeks 3 and 4 experimental outlooks, the NAEFS precipitation outlooks, dynamical models including the CFSv2 and GFS, climatology, El Nino composites, and initial conditions.

During the second half of January, widespread heavy precipitation overspread northern California, with COOP and Automated Weather Data Network provisional 14-day liquid departures from normal exceeding 7 inches over the higher elevations of the northern Sierras and near the Modoc Plateau. The widespread rainfall and mountain snows resulted in further drought reductions across northern California, including a reduction in exceptional drought (D4) coverage over the northern Sierras. Southern California missed out on the recent precipitation, and drought conditions there remained unchanged during the past month. The latest SNOTEL snow water equivalent (SWE) values were above normal across the Sierras, ranging between 90 and 150 percent of normal. According to analysis from the Advanced Hydrologic Prediction Service, the northern Sierra mountains received more than 3 inches of additional precipitation, liquid equivalent, on January 29.  The current state of the snowpack across the Sierras along with heavy precipitation during late January favors drought improvement or removal across northern and central California. Rain and high-elevation snow (locally more than 2 inches, liquid equivalent) is shifting into southern California at the end of January which is expected to result in drought improvement for parts of this region. Early to mid-February presents a more challenging forecast scenario. Climate impacts associated with El Nino events are typically most pronounced in the late winter, which would normally tilt the odds towards above-median precipitation. A longwave ridge is forecast to build across the western CONUS during early February; however, which would promote below-normal precipitation and above-normal temperatures across California. Beyond Week-2, dynamical model solutions diverge considerably, with the ECMWF maintaining the ridge, and the CFS bringing a mean trough closer to the coast, which would allow for renewed storm activity across much of California. Both models depict some undercutting of this ridge later in Februrary, which would allow moisture into southern California. The updated CPC monthly outlook maintains enhanced chances for above-median precipitation across most of California during February, with the highest probabilities along coastal southern California. Due to the more uncertain longer range forecasts; however, drought persistence is anticipated across the California Deserts and Basin and Range regions. Additionally, drought is anticipated to ease, but not end, across the Sacramento Valley.
Forecast confidence for California is moderate.

Widespread heavy precipitation also overspread the Northwest during January, resulting in widespread drought reductions. SNOTEL SWE values range between 125 and 175 percent of normal across the southern half of Oregon, and between 90 and 150 percent of normal across the Cascades, reflecting a good start to the water year. SWE values are near to below normal across the northern and central Rockies, with the poorest conditions (50 to 75 percent of normal) across the easternmost ranges of Montana and Wyoming. As with California, a series of storm systems in the near term is anticipated to bring widespread heavy rainfall and mountain snows to the Northwest and the northern and central Rockies, with liquid accumulations of 2 to 4 inches at the higher elevations. This precipitation is anticipated to bring additional drought relief to southwestern Oregon, northeastern Oregon, northern Idaho, and northwestern Montana. Due to topography, less precipitation is anticipated to reach existing drought areas across east-central Oregon and southwestern Idaho. Near to above-median precipitation is favored across the northern Rockies during early February, but the ENSO climate signal is associated with below-median precipitation across this region, and this signal is maintained in the updated CPC February monthly outlook. Therefore, drought persistence is favored for regions of the Northwest and northern Rockies where the precipitation at the end of January and very early February is expected to have less of an impact.
Forecast confidence for the Northwest and the northern and central Rockies is low to moderate.

Near to above-median precipitation resulted in drought reductions across parts of the Great Basin and Desert Southwest. Basin SWE conditions generally range between 90 and 175 percent of normal across Nevada and the Four Corners states. On January 31 and February 1, Widespread heavy precipitation is forecast across the Great Basin, central and southern Rockies and higher elevations of Arizona. This precipitation is expected to be sufficient for additional drought improvements or removal across central Utah and southeastern Arizona. Less precipitation is forecast to accumulate across western Utah and the Desert Southwest due to topography and the predicted storm track. Although El Nino conditions favor enhanced precipitation across the Great Basin and southern Rockies, the CPC 8-14 day outlook forecasts enhanced chances for below-median precipitation. Longer range dynamical model guidance is mixed, with the CFS forecasting below-median precipitation across the Four Corners and the ECMWF forecasting above-median precipitation in far southern Arizona and New Mexico. The updated CPC monthly outlook maintains enhanced chances for above-median precipitation across the Great Basin and Four Corners regions, but with lower probabilities than in the initial forecast released on 21 January. Based on these outlooks, additional drought improvements beyond the near term are likely to be limited, with persistence the most likely outcome.
Forecast confidence for the Southwest, Great Basin, and Four Corners states is low to moderate.

Drought and abnormal dryness have expanded across the High Plains of Wyoming and Montana during the past month. Climate anomalies associated with ENSO events favor below-median precipitation; however, the latest CPC 8-14 day outlook favors above-median precipitation across the northern Plains. A return to below-median precipitation is indicated by longer range dynamical model guidance through late February, and the updated CPC monthly outlook maintains enhanced chances for below-median precipitation over all of Montana. Therefore, drought persistence is forecast for the area of moderate drought (D1) across the Bighorn region, but no additional development is anticipated during February. Drought removal is forecast for the small remaining D1 area in North Dakota due to remaining snow cover after recent melting, and the 8-14 day outlook.
Forecast confidence for the northern Plains is moderate.

Following a crippling blizzard that impacted much of the mid-Atlantic and far southeastern New England, only a small strip of moderate drought (D1) remains across northern Connecticut, central Massachusetts, southeastern New Hampshire, and far southeastern Maine. A second small drought area remains near Niagara Falls in western New York. During the next 7 days, precipitation amounts between 0.75in and 1.5in are forecast to overspread much of the Northeast. This precipitation, along with a tilt in the odds for above-median precipitation forecast in the monthly outlook are likely to result in drought removal for the lingering drought areas across the Northeast.
Forecast confidence for the Northeast is high.

Consistent with the ongoing strong El Nino, below-median rainfall across Hawaii during the past month has resulted in expansion of abnormal dryness (D0) and moderate drought (D1). As of the January 26 U.S. Drought Monitor, D0 or D1 conditions cover all of Hawaii except for eastern Molokai and Niihau. During February, dynamical model guidance depicts a continuation of the suppressed rainfall climate signal. Therefore, further expansion of drought across all of Hawaii is anticipated.
Forecast confidence for Hawaii is moderate to high.

During El Nino events, the dry season across Puerto Rico tends to be wetter than average. There is no clear wet signal among the dynamical models; however, with many depicting a region of suppressed rainfall extending across much of the northern Caribbean. Therefore, drought persistence is the most likely outcome by the end of February across Puerto Rico.
Forecast confidence for Puerto Rico is moderate to high. 

Forecaster: Adam Allgood and Brad Pugh

Next Monthly Drought Outlook issued: February 29, 2016 at 3:00 PM EST