Discussion for the Seasonal Drought Outlook
Tools used in the Drought Outlook included the
official CPC precipitation outlook for January 2009 and January – March 2009, various short and medium-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 CFS seasonal precipitation forecast, and climatology.
During the past week, substantial drought relief
has occurred across the upper southern Appalachians and drought was eliminated in Alabama. The watershed of
Georgia’s Lake Lanier received 2 to 4 inches of rainfall, resulting in a one foot rise of the lake’s level
since December 9. Across the upper Ohio Valley, additional moderate to heavy rainfall amounts can be expected
in the short-term. The 6-10/8-14 day outlooks also call for above normal precipitation. Seasonal precipitation
tools indicate that drought improvement should continue during the remainder of the winter, especially in
southern Ohio, Kentucky, and eastern Tennessee. Odds for improvement decrease slightly farther south in
northeast Georgia and the upstate of South Carolina, but climatology favors continued improvement. However,
the protracted hydrological drought may linger into the spring.
Confidence for the upper Ohio Valley: High
Confidence for the southern Appalachians: Moderate
In Florida, climatology along with forecast tools
at all time ranges indicates expansion of drought across the northern and central peninsula. If drought
development occurs, an increase in wildfire activity would likely occur during the spring.
Confidence for Florida: High
In the Great Lakes region, short and medium-range
forecasts are fairly wet while the seasonal tools are noncommittal. The outlook calls for some improvement due
to the lack of a signal during the January – March 2009 period. The most likely area for improvement is the
southern extent of drought in Wisconsin.
Confidence for Great Lakes region: Moderate
In southern and eastern Oklahoma, the January –
March 2009 seasonal outlook calls for above normal precipitation. Also, precipitation normals increase during
March across southeast Oklahoma. Therefore, the outlook indicates improvement.
Confidence for southern and eastern Oklahoma: Moderate
In Texas, drought should persist in south-central
areas and may expand to the south towards the lower Rio Grande. Climatology is quite dry for this time of year,
especially across the western half of the ongoing drought area. The January – March 2009 seasonal outlook calls
for a tilt in the odds towards below normal precipitation across western and southern Texas. Drought development
is forecast for areas of western Texas that are currently experiencing abnormal dryness.
Confidence for Texas: High in western areas; moderate in eastern areas
Across the widespread drought area covering
California, the Great Basin, and parts of the Rockies, changes to the present drought status vary with location
and may not be realized until the spring snow melt occurs. A poor start to the wet season has resulted in low
snow-water content values across this region. However, during the remainder of December and perhaps into the
beginning of the New Year, a persistent trough should result in above normal precipitation and below normal
temperatures. This expected weather pattern should increase snowpack, a critical source of water for the region. The
highest precipitation amounts in the short and medium range are expected in California with lower amounts
across northern Nevada and southern Idaho where some improvement is forecast. With a few seasonal tools
favoring a return of dryness, forecast confidence in the improvement and some improvement is tempered. Although
the January – March 2009 seasonal outlook calls for equal chances for above, below, or near normal
precipitation, the improvement is based on the wet, cold pattern during the next two or three weeks and
Confidence for the West: Moderate
Across the Hawaiian Islands, relief has occurred
since late November. Improvement should continue with the wet season underway.
Confidence for Hawaii: High