October - December 2012

Outlook Graphic: GIF   PDF 

Latest Seasonal Assessment - Drought amelioration occurred across Texas, the middle Mississippi and Ohio Valleys, and the eastern U.S. since late August, while drought expanded and intensified across the northern Great Plains, upper Mississippi Valley, and northern Rockies. Drought is expected to persist across most of the northern Great Plains and upper Mississippi Valley, while prospects for improvement increase across the Ohio Valley, middle Mississippi Valley, and the southern Great Plains. Development forecast across the Pacific Northwest and northern California is consistent with the CPC monthly and seasonal outlooks calling for enhanced odds of below median precipitation during an increasingly wet time of year. The end of the monsoon offers decreasing chances for widespread improvement and persistence is forecast for the Southwest. However, forecast confidence is low since precipitation tools indicate enhanced chances for near or above median precipitation during early to mid-October. Continued improvement is expected for the small areas of drought across the mid-Atlantic and western New York. No changes were made to the previous outlook in Hawaii where persistence or development can be expected. Puerto Rico should be closely monitored for drought development following an unusually dry September with San Juan observing its 6th driest September on record.

Tools used in the U.S. Drought Outlook (USDO) included the official CPC temperature and precipitation outlooks for October 2012 and the long lead forecast for October through December 2012, various medium- and short-range forecasts and models such as the 6-10 day and 8-14 day forecasts, the most recent 384-hour GFS total precipitation amounts, the soil moisture tools based on the Constructed Analog on Soil (CAS) moisture, the Climate Forecast System (CFS, versions 1 and 2), the four-month Palmer drought termination and amelioration probabilities, climatology, and initial conditions. El Niño precipitation anomalies for October through December were also considered.

At the beginning of October, a widespread area of moderate to heavy rainfall (locally more than 5 inches) resulted in a 1-category improvement to drought categories across northern Georgia and northeast Alabama. Although October and November are a relatively dry time of year for the Southeast, the CPC outlook for OND calls for enhanced odds for above median precipitation for eastern Alabama and Georgia. Therefore, some improvement is forecast for this region but long-term precipitation deficits are not expected to be eliminated.
Forecast confidence for Southeast is moderate.

Frequent rainfall during the past month led to improvement across the mid-Atlantic and western New York. The 6-10/8-14 day outlooks on October 3 along with updated October precipitation outlook call for above median precipitation for these areas. Soil moisture currently ranks mostly above the 30th percentile. Since above rainfall is favored during the remainder of October, improvement can be expected for the small areas of ongoing drought across the mid-Atlantic and western New York.
Forecast confidence for the mid-Atlantic and western New York is high.

Due to an increase in rainfall since late August which began with the remnants of Isaac, significant amelioration of drought occurred across Arkansas, southeast Missouri, and the eastern Corn Belt. Soil moisture levels and stream flows have mostly recovered in these areas since mid-summer. The updated October precipitation outlook calls for a tilt towards above median precipitation across much of the Ohio Valley. Due to expected wetness during October and recent alleviation of drought since late August, improvement is forecast across the middle Mississippi and Ohio Valleys.
Forecast confidence for the middle Mississippi Valley and Ohio Valley is moderate.

According to the USDM, extreme to exceptional drought covers nearly all of Oklahoma with varying drought intensity across Texas. A relatively dry climatology favors persistence across the Oklahoma Panhandle and the northwest Texas Panhandle. Prospects for improvement increase across the remainder of Oklahoma and north Texas where climatologically, conditions do not become significantly drier during OND. Other factors that support some improvement or improvement across much of Oklahoma and Texas include: several inches of precipitation indicated by the 384-hour forecasts from the 0/6z gfs models, the 6-10/8-14 day outlooks from October 3 favoring near to above median precipitation, and the CPC seasonal outlook for OND calling for enhanced odds of above median precipitation across central and south Texas.
Forecast confidence for Oklahoma and Texas is moderate.

During the past month, drought increased to cover nearly all of the northern Great Plains and upper Mississippi Valley with drought intensifying across the central Great Plains. According to the USDM, most of Kansas, Nebraska, and southern South Dakota are designated in the extreme or exceptional drought category. A relatively dry climatology favors persistence across the northern/central Great Plains and upper Mississippi Valley. However, some improvement is forecast in northeast North Dakota and extreme northern areas of Minnesota where 1 to 2.5 inches of precipitation are expected at the beginning of the outlook period.
Forecast confidence for the northern/central Great Plains and upper Mississippi Valley is high.

During September, drought expanded in Montana where dry weather was accompanied by unseasonably warm temperatures. A relatively dry climatology favors persistence across Montana. Although development remains forecast across Montana due to the dry initial conditions, some precipitation at the beginning of the outlook period reduces forecast confidence.
Forecast confidence for the northern Rockies is low.

During September, dry weather accompanied by unseasonably warm temperatures also affected the Pacific Northwest. As of October 3, multiple large wildfires continue to burn across the Pacific Northwest. Since tools on all time scales indicate enhanced odds for below median precipitation, persistence or development is forecast for the Pacific Northwest and northern California. El Niño precipitation composites indicating below median precipitation across these areas are also considered.
Forecast confidence for the Pacific Northwest and northern California is moderate.

Persistence is forecast for the Southwest and central Rockies with precipitation associated with the monsoon ending. Since the 6-10/8-14 day outlooks from October 3 favor near to above median precipitation across the Southwest and weak signals exist among the seasonal precipitation tools, forecast confidence is low for persistence. Climatology tends to be dry across southern Arizona during OND.
Forecast confidence for the Southwest and central Rockies is low.

In Hawaii, October through December become progressively wetter. However, the long-lead forecast indicates enhanced chances for below-normal rainfall. As a result, drought is expected to persist in existing areas and slowly expand into other parts of the state, much like the previous Drought Outlook. Still, the fact that the Islands are getting climatologically wetter during the period does imply that the chances for drought-relieving rains improve later in the period, even if only based on climatology.
Forecast confidence for Hawaii is low.