November 2009 - January 2010

Outlook Graphic: GIF   PDF 

Latest Seasonal Assessment - Widespread precipitation across much of the country during the last half of October continued to offer relief to several of the remaining areas still experiencing drought, including California, southern Texas, and northern parts of Minnesota and Wisconsin. Eastern North Carolina and Arizona were among the few areas seeing below-normal rainfall during October, and dryness either persisted or worsened. The outlook for November 2009 to January 2010 continues to indicate drought improvement for California, southern Arizona, southern Texas, and eastern North Carolina. Improvement is also seen for northern Wisconsin. Ongoing drought with some improvement is forecast for central and northern Arizona, Nevada, and north-central Washington. The current El Niño is expected to last through this winter, tilting the odds toward improvement in California, Arizona, and Texas. In contrast, drier than normal conditions will worsen existing severe to extreme drought over parts of Hawaii if early wet season rainfall does not materialize.

Tools used in the Drought Outlook included the official CPC precipitation outlook for November 2009 and the long lead forecast for November 2009 - January 2010, the four-month Palmer drought termination and amelioration probabilities, various medium- and short-range forecasts and models such as the 6-10 day and 8-14 day forecasts, the soil moisture tools based on the GFS model and the Constructed Analogue on Soil (CAS) moisture, the Climate Forecast System (CFS) seasonal precipitation forecasts, El Niño precipitation and temperature composites for November - January, climatology, and initial conditions.

For eastern North Carolina, improvement continues to be indicated based on normal to above-normal rains for the first half of November and supportive seasonal precipitation and soil moisture forecasts from the CFS. The experimental runoff forecasts for the El Niño subset years issued by the University of Washington do show some enhanced risk for drought through 3 months over northeastern North Carolina, and the most recent GFS run on November 4 forecasts less than 1 inch of rain over the 384-hour period. As a result, confidence of the forecast is lowered to moderate from high.
Forecast confidence for the Carolinas is moderate.

October rains eased the drought in Minnesota and northern Wisconsin. Given the much more marginal drought situation in Wisconsin due to the increased moisture levels and extended-range forecasts showing the odds tilting wet, the forecast is changed from a mix of some improvement and improvement to straight improvement. To the northwest, medium and long-range models show somewhat less chances for precipitation over northern Minnesota, so the forecast of some improvement remains.
Forecast confidence for Wisconsin and Minnesota is moderate.

Additional relief from the protracted drought affecting parts of southern Texas appears likely by the end of the year. Forecasts from November through the end of January favor above-normal precipitation, and the development of moderate El Niño conditions also favors enhanced precipitation during the outlook period.
Forecast confidence for Texas is high.

Recent short-term dryness has worsened the drought in the Southwest, especially in Arizona. Little change is anticipated during the first half of November. Soil moisture forecasts based on the subset of El Niño years plus the latest CFS precipitation forecast for NDJ continue to suggest a slight tilt of the odds to wetness over southern Arizona, with the odds of improvement lessening toward the north. Due to the drier short-term outlook and some seasonal forecasts indicating lesser odds for improvement during NDJ, including the CFS soil moisture for January, the area of improvement is reduced slightly in the south and the overall confidence for the region is reduced.
Forecast confidence for the Four Corners region is low.

The persistence forecast for north-central Washington is changed to some improvement to reflect forecasts for above-normal precipitation during the first half of November. The drier areas forecast in the CPC seasonal precipitation outlook are to the west and the east of this drought area. The rain-shadow effect should lead to relatively low totals, and the CFS indicates below-normal precipitation for November-January, so forecasting significant improvement is not warranted.
Forecast confidence for Washington is low.

Hawaii is forecast to see below-median rainfall during the upcoming winter, consistent with an ongoing El Niño. Drier than normal conditions will worsen existing severe to extreme drought over portions of the state if early wet season rainfall does not materialize. The latest GFS model run does indicate several opportunities for rainfall during the first half of November, so the outlook continues to depict some improvement, but drought will likely continue.
Forecast confidence for Hawaii is low.