Tools used in the Drought Outlook
included the official CPC precipitation outlook for December 2009 and the long lead forecast
for December 2009 - February 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 December - February, climatology, and initial conditions.
Short-term dryness has led to
drought development in east-central parts of the Florida peninsula. Since October 1, the rainfall deficit at
Melbourne, FL is nearly 6 inches. Although drought conditions may expand across the Florida peninsula during
the next few weeks, the ongoing El Niño strongly favors above-median precipitation during the winter and thus
improvement in the long-term.
Forecast confidence for Florida is high.
Drought coverage and intensity has
decreased in the upper Mississippi Valley, but severe drought continues in northwest Wisconsin. Due to a lack
of any forecast signals for wetter than normal conditions and a relatively dry climatology during the outlook
period, drought is expected to persist. Precipitation for this region typically increases later in the
Forecast confidence for Wisconsin is low.
Additional relief from the
protracted drought affecting parts of southern Texas appears likely during the winter. Forecasts from
December through the end of February favor above-median 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 or no change can be expected during the
remainder of November. El Niño composites indicate a tilt in the odds toward above-median precipitation
during the outlook period. The CPC seasonal forecast shows slightly increased odds for above-median
precipitation for southern Arizona but equal chances for above, below, or near normal precipitation across
the reminder of the State. With these considerations, improvement is more likely in southern Arizona.
Forecast confidence for the Four Corners region is moderate.
Since October 13 when a very strong
storm affected northern and central California, drier than normal conditions have prevailed across the state.
At the beginning of the outlook period, moist onshore winds should bring several inches of precipitation to
northern California. By the end of November, enhanced rainfall associated with a MJO event is expected to
become established across the western pacific. This MJO activity may affect the circulation pattern across
the north Pacific and contribute to wet conditions along the West Coast. Later in the winter, the storm track
is expected to gradually shift south along the West Coast. El Niño composites along with the CPC seasonal
outlook favor above-median precipitation during December – February. Therefore, improvement is forecast in
Forecast confidence for California is high.
Although the short-term forecast is
quite wet across central Washington, the CPC seasonal forecast indicates higher odds for below-median
precipitation. Drought persistence and development is forecast in central and eastern Washington.
Forecast confidence for Washington is low.
Hawaii is forecast to receive
below-median rainfall during the upcoming winter, consistent with an ongoing El Niño. Drier than normal
conditions will worsen existing severe to extreme drought and likely result in drought expansion across the
remainder of the state.
Forecast confidence for Hawaii is moderate.