January - March 2013

Outlook Graphic: GIF   PDF 

Latest Seasonal Assessment - During the previous four weeks, a series of storms spread above average precipitation across the Northwest, northern Rockies, and northern California, while dry conditions exacerbated drought in the southern Plains and southern Atlantic states. A very active weather pattern is expected to develop during the upcoming two weeks, beginning with heavy snows from the central Plains through the Great Lakes region. Wet weather is anticipated across the eastern half of the U.S., bringing a potential for drought reduction along the Mississippi River Valley and the interior Southeast. A continued wet pattern in the northern Rockies may also bring some drought relief, but a persistently dry outlook for the southern high Plains is expected to exacerbate long standing drought conditions in western Texas and southern New Mexico. General persistence of extreme to exceptional drought is expected across the Plains states during the dry season.

Tools used in the U.S. Drought Outlook (USDO) included the official CPC temperature and precipitation outlooks for January 2013, the long lead forecast for January through March 2013, various short- and medium-range forecasts and models such as the 6-10 day and 8-14 day forecasts, the NAEFS precipitation outlooks, the soil moisture tools based on the Constructed Analog on Soil (CAS) moisture, the Climate Forecast System (CFS version 2), the 384-hour total precipitation forecasts from several runs of the GFS, the four-month Palmer drought termination and amelioration probabilities, climatology, and initial conditions.

During the previous two weeks, increased rainfall fell across Hawaii's northeastern slopes, bringing drought relief, particularly to the Big Island. Negative sea surface temperature anomalies near Hawaii weakened during early December. Incipient El Nino conditions across the equatorial Pacific weakened during the autumn, and ENSO neutral conditions are now expected for the northern hemisphere winter and early spring months. Based on these factors, the CPC seasonal outlook for Hawaii maintains equal chances of above, near, or below median precipitation. The January monthly forecast tilts the odds towards below median precipitation. Given that the winter and early spring months comprise the rainy season, however, some improvement based on climatology is possible across Hawaii. A small area of improvement is indicated along the northeastern sector of the Big Island, where continued drought relief is most likely.
Forecast confidence for Hawaii is moderate.

In the western U.S., a series of storm systems brought heavy rainfall and mountain snows to the Cascades and Sierra Nevadas under a persistently negative phase of the Pacific North American oscillation. Positive precipitation anomalies were highest across Oregon and northern California, where further drought reduction occurred. A small area of heavy rainfall also eliminated drought conditions across extreme southeastern California and southern Nevada. The highly active storm pattern is expected to continue during the upcoming week, with additional precipitation amounts exceeding 10 inches possible across northern California. Enhanced precipitation is likely to continue into the week 2 period as well, with the highest probabilities of above average precipitation shifting southward into the lower Sierra Nevadas and the Great Basin region. During January, the CPC monthly outlook indicates enhanced odds of above median precipitation continuing across the Pacific Northwest, including extreme northern California and northwestern Nevada. Based on these factors, some improvement is expected across the drought areas of the western U.S. Improvement is expected along the northwestern boundary of the extant drought areas in northeastern California, south central Oregon, and extreme northwestern Nevada. The primary reason for not extending improvement southward through central California is an enhanced probability for below median precipitation in the southwestern U.S. during the upcoming three month period, which is based largely on CFS version 2 forecasts.
Forecast confidence for the western U.S. is moderate to high.

Precipitation averaged more than 200 percent of normal across portions of Idaho and extreme western Wyoming during the previous month, contrasting with areas of intensifying drought throughout the remainder of Wyoming and parts of southern Montana. A stormy pattern is expected to bring additional mountain snows to much of the northern Rockies during the upcoming week, with highest accumulations expected across northern and central Idaho, which are outside the existing drought areas. Enhanced chances of above average precipitation continue through week 2 in southern Idaho, Wyoming, and Montana. The CPC January outlook and the JFM seasonal outlook both maintain enhanced chances of above median precipitation in southern Idaho, western Montana, and northwestern Wyoming. Therefore, some improvement of drought conditions are expected in these regions, with persistence expected across the remainder of the northern Rockies.
Forecast confidence for the northern Rockies is moderate.

Outside of western and central Arizona, scant rainfall was observed across the southwestern U.S. during the previous month. Drought conditions intensified across portions of west central Texas. During the upcoming week, stormy weather is expected to bring some precipitation to the southern Rockies, but mostly dry weather is expected to persist in western Texas and southern New Mexico. High winds associated with developing low pressure in the Plains are expected to generate red flag conditions and dust storms across a large swath of Texas and New Mexico. Beyond week 2, the CPC monthly and seasonal outlooks both maintain enhanced odds of below median precipitation for the Southwest. Based on these factors, drought persistence or intensification is expected for most of the Southwest. Drought development is expected across areas of western Texas that are currently abnormally dry.
Forecast confidence for the Southwest is high.

Generally below average precipitation fell across the Plains states during the previous month. In the short term, a potent winter storm developing in the central Plains is expected to push northeastward into the Great Lakes region, bringing blizzard conditions and heavy snowfall to portions of Kansas, Colorado, and Nebraska. Liquid accumulations are expected to remain generally below one inch. The CPC 8 to 14 day outlook maintains enhanced odds of above average precipitation for most of the Plains outside of the southern high Plains, but below median or near median precipitation amounts are favored for the remainder of the three month period. The winter and early spring months are a dry time of year for the Plains, therefore, impacts from precipitation anomalies are expected to be smaller than during the warmer months. Based on these considerations, general persistence of drought is expected across the Plains.
Forecast confidence for the Plains states is moderate to high.

During the previous several weeks, above average precipitation fell across central and northeastern Minnesota, while abnormally dry weather dominated the remainder of the Great Lakes and Ohio Valley regions. In the short term, a winter storm is expected to bring heavy snow across a swath extending from Iowa through Michigan, with the highest liquid totals falling across southern Wisconsin, northern Michigan, and the Ohio River Valley. During the week 2 period, enhanced chances for above average precipitation remain, as additional storm systems develop and impact the eastern U.S. The CPC January outlook indicates greater odds for above median precipitation for the upper Midwest and the Ohio and Tennessee Valleys, while the 3 month outlook tilts the odds towards wet across the middle Mississippi and Ohio River Valleys. Therefore, drought improvement is expected across the remaining areas of the Great Lakes region and Ohio Valley. Persistence is maintained for Minnesota, where short term precipitation amounts are expected to be smaller, and also due to the winter freezing of streams and lakes.
Forecast confidence for the upper Midwest, Great Lakes, and the Ohio Valley is moderate.

Above average rainfall was observed across southeastern Texas and much of Louisiana during the previous two weeks, ameliorating drought in central Louisiana. During the upcoming week, winter storms traversing the Mississippi Valley are expected to generate widespread rainfall in association with cold fronts. Precipitation amounts nearing an inch are possible for extreme eastern Texas and all of Louisiana. During the week 2 period, additional rainfall is expected for eastern Texas and Louisiana. Additionally, the CPC monthly outlook for January tilts the odds in favor of above median rainfall for northeastern Texas and Louisiana. Therefore, drought improvement or elimination is expected for extreme eastern Texas and the remaining drought areas of Louisiana. Some improvement of short term drought conditions is possible along the northeastern Gulf Coast of Texas, which is close to the edge of the forecasted higher precipitation corridor.
Forecast confidence for far eastern Texas and southwestern Louisiana is moderate to high.

During the previous month, below average rainfall fell across the drought areas of the Southeast, promoting continued drought persistence and intensification. During the upcoming 7 day period, an active pattern across the eastern U.S. will promote the development of several winter storms with attending cold fronts pushing through the southeastern U.S. Precipitation amounts of 3 to 4 inches are expected across the core drought regions of northern Georgia and western North Carolina. The active pattern is forecast to continue through week 2, with a probability of above average precipitation greater than 50 percent in the interior Southeast. A continued wet pattern through January is indicated for the southeastern piedmont by the CPC monthly outlook, while the seasonal forecast tilts the odds towards above median rainfall across far northern Georgia and western North Carolina. Additionally, the January through March period is a climatologically wet time of year for the interior Southeast. Based on these considerations, drought improvement is likely for east central Alabama, the northern two thirds of Georgia, and the western Carolinas. Some improvement is indicated across the southern and coastal Southeast, where short term precipitation amounts are expected to be smaller and where the climatology is somewhat drier.
Forecast confidence for the Southeast is moderate.

During the previous month, drought conditions expanded across the southern Atlantic states along the Fall Line of North Carolina and Virginia. During the upcoming two week period, an active weather pattern in the eastern U.S. will promote the development of several winter storms. Current storm track forecasts bring the bulk of the precipitation associated with these storms across the Ohio and Tennessee Valleys and into the Northeast, though significant precipitation is still expected for the southern Atlantic states. 60 day precipitation deficits across North Carolina and Virginia range between 4 and 8 inches, so it is not certain that the forecasted storminess will provide enough moisture to significantly reduce the long term drought conditions. The CPC January outlook tilts the odds slightly towards above median precipitation in this region, and the seasonal outlook maintains equal chances of below, near, or above median precipitation through March. Climatologically, the January through March period is a drier time of year for this region. Based on these considerations, some improvement of drought is indicated.
Forecast confidence for eastern North Carolina and Virginia is low.