Tools used in the Drought Outlook included the
official precipitation outlook for February-April, 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, and climatology.
Recent heavy precipitation across the
Eastern U.S. has resulted in much improved conditions across the Ohio Valley and the central and southern
Appalachians. Across the coastal Southeast, drier conditions have recently prevailed, especially across
northern and central Florida, where streamflow values have been abnormally low. The Climate Prediction
Center is calling for below average rainfall during both the month of February 2009 and the season of
Feb-Mar-Apr 2009. The prominent dry signal over the Southeast (as well as the Ohio Valley wet signal) is
consistent with historical La Niña cases. In addition, the Drought Outlook favors a slight expansion of
dryness across coastal South Carolina during this forecast period. Some improvement is noted over the
southern Appalachians/Piedmont area, which falls in between the anticipated dryness near the coast and
wetness over the Ohio Valley.
Confidence for upper Ohio Valley: High
Confidence for the southern Appalachians: Moderate
Confidence for Florida and southeast Georgia: High
In Wisconsin and adjacent portions of Minnesota
and upper Michigan, the best chances for improvement are for the southern areas which have been closer to
the storm track over the Midwest in recent weeks. More northerly areas should still experience some
improvement, especially with the near-term forecasts of Alberta Clippers moving across the area.
Confidence for Great Lakes region: Moderate
Across the southern Plains, some expansion of
the Texas drought area is forecast. This is based on recent trends, medium-range forecasts and La Niña
soil moisture composites. La Niña composites show that there is a tilt in the odds for dryness for the
upper Texas coast during late winter. Higher rainfall climatology, as well as the 2-week total precipitation
from the two gfs model runs noted above suggest that the dryness will not expand across northeast
sections of Texas. Confidence decreases a bit across the southern Plains in April, as severe weather events
begin to increase.
Confidence for southern Plains: High in western areas; moderate in eastern areas
In southeast Colorado, climatology favors
persistence, while in southwest North Dakota, La Niña-related storminess should lead to improvement in
the current drought.
Confidence for North Dakota and southeast Colorado: Moderate
In northwest Montana, La Niña-related storminess
is expected to be offset somewhat by the climatological rain shadow just east of the Divide. Therefore,
some improvement is forecast.
Confidence for northwest Montana: Moderate
Across the widespread drought areas covering
California and the Great Basin, minor revisions were made to the previous outlook, released on December 31st.
Based on La Niña composites and the latest model guidance for the next couple of weeks, prospects
for improvement are slim for most of California and Nevada. It is thought that the mean jet stream and
associated storm track will reside mainly north of this area. A small area of some-improvement is likely
over the northwestern part of the state.
Confidence for the West: Moderate
For Hawaii, significant relief has occurred
during the past few weeks. With the wet season well underway and the possibility of Kona Lows during La Niña
winters, improving conditions are deemed the best bet.
Confidence for Hawaii: High