Tools used in the Drought Outlook
included the official CPC precipitation outlook for September 2009
and the long lead forecast for September – November 2009, 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 September-November, climatology, and initial conditions.
The Wisconsin-Minnesota drought
area has seen near to above normal precipitation over the most recent 30-day period. The area is forecast to
see little precipitation during the short range period. The CPC 6-10 day and week 2 forecasts indicate near to
above normal precipitation for the region, especially for the western portion of the area. The 30-day forecast
for September indicates equal chances of a given precipitation anomaly category for the northeastern portion
of the drought region, and above normal precipitation for the southern portion of the area. The 90-day forecast
for September-November shows equal chances for each of the precipitation categories for Sep-Nov. The official
Sep-Nov temperature forecast for the region from CPC indicates above normal temperatures. The CFS forecast for
Sep-Nov indicates mostly near-normal precipitation for the region while the El Niño composites for the same
period show near to below normal precipitation for the area. Various soil moisture tools suggest the region
will see some improvement over the next three months. For these reasons a forecast of some improvement will be
continued for the eastern portion of the drought region while improvement is indicated for the southern and
Forecast confidence for Wisconsin and Minnesota is moderate.
For eastern North Dakota rainfall
has mostly been near normal over the last 30 days. The HPC forecast for days 1-5 depict little to no
precipitation over the area. 0z and 6z runs of the GFS show light 2-week precipitation totals over the area.
The 6-10 day and 8-14 day forecasts indicate a tilt of the odds for above normal precipitation for the region.
The CPC monthly and seasonal precipitation outlooks indicate equal chances for each of the possible
precipitation categories. El Niño composites for Sep-Nov suggest above normal precipitation, while the CFS
forecast for Sep-Nov is for near to above normal precipitation for the region. For these reasons a forecast of
improvement will be retained for the area.
Forecast confidence for North Dakota is moderate.
For Southeast Nebraska the drought
area has received near to above normal precipitation over the last 30 days. The latest drought monitor no
longer indicates drought for this region although a small area retains the abnormally dry designation. Short
and medium ranges forecasts suggest the area will have above normal precipitation. The 30-day forecast for
September indicates the likelihood of above normal precipitation while the 90-day forecast for
September-November shows equal chances for each of the precipitation categories during the period. The CFS
forecast for September-November shows near normal precipitation while the El Niño composites for
September-November indicate a likelihood of near to above normal precipitation for the region. For these
reasons it is not likely that drought will re-develop over the region during the forecast period.
In northwestern Oklahoma near to
above normal precipitation over the past 30 days has eliminated drought conditions although parts of the area
remain abnormally dry. The HPC precipitation forecast for days 1-5 for the region indicate little to no
precipitation for the region. The CPC 6-10 and week 2 forecasts indicate above normal precipitation is likely
for the region. According to the CPC forecasts for September and September-November there is little tilt in
the odds for a given precipitation category. The CFS forecast for September-November shows above normal
precipitation for the region, while El Niño composites indicate mostly near normal precipitation for the area.
For these reasons the region is not expected to see drought re-development.
In Texas, the lingering small
drought area in north-central Texas is forecast to experience only light precipitation during the short range
period. The CPC 6-10 and week 2 forecasts indicate near to above normal precipitation for the region. The CPC
30-day forecast for September and 90-day forecast for September-November indicate equal chances for each of the
possible precipitation anomaly categories. CFS forecasts for September and September-November suggest above
normal precipitation for the region while El Niño composites indicate near to above normal precipitation. For
these reasons a forecast of improvement is indicated. Southern and south-central Texas continues to endure one
of their most intense droughts on record. The odds for significant improvement increase considerably starting
in November based on composites from historic El Niño episodes and seasonal forecasts from the global models,
such as the CFS, but the outlook into October is not as clear cut. Monthly El Niño composites indicate the dry
signal for southern Texas ends after September, while the CFS is depicting above-normal rains for September
over the far northern portion of this drought region. The weight of the evidence from the various seasonal
models, El Niño soil moisture composites, and forecasts from the short term out to the 3-month time periods
suggests that the odds for some improvement increase toward the north and the coast. For these reasons southern
Texas is forecast to have some improvement over the current drought areas, except over the coastal sections and
the northeastern part of the drought region, where improvement will be indicated.
Forecast confidence for Texas is moderate.
Recently rainfall has been near to
below normal over the drought area in Louisiana/Mississippi. The HPC forecast for days 1-5 indicates light
precipitation for the region. The CPC 6-10 day forecast shows near normal precipitation is likely while the
week 2 forecast indicates above normal precipitation for the region. The CPC monthly forecast for September
indicates no tilt of the odds for above or below normal precipitations while the seasonal forecast for
September-November shows a relatively high probability for above normal precipitation. The CFS forecast
indicates near to below normal precipitation is favored during September-November, while the El Niño composites
for September-November suggest above normal precipitation. For these regions a forecast of improvement is
Forecast confidence for Louisiana and Mississippi is high.
The latter part of the Southwest
monsoon season has been weak, especially in Arizona, where several areas have quickly dried out over the last
few weeks and small regions of drought have recently developed over the eastern part of the state. It now
appears that the majority of the moisture associated with tropical system Jimena will remain south of the
U.S.-Mexican border. On the other hand some of the residual moisture from the tropical system may get drawn
northward in association with a burst of monsoonal activity expected over the region. CFS forecasts indicate
near to above normal precipitation for September-November while El Niño composites for the same period indicate
near to below normal precipitation for much of the region. An area of improvement is depicted over the southern
section of eastern AZ, an area of some improvement is depicted for central Arizona, and an area of persist is
forecast for the northwestern most portion of the current drought area. Further to the east over New Mexico
longer range forecasts, especially the CFS precipitation forecast for September-November, paint an optimistic
picture for near to above normal precipitation so a forecast of some improvement is specified, except over the
southern part of the drought region where the expectation of late season monsoonal activity leads to a forecast
Forecast confidence in Arizona and New Mexico is moderate.
The Outlook continues to indicate
persisting drought in California and Nevada. Although the West Coast typically sees a pickup in rainfall
during October, little change in drought conditions is anticipated before December, when much larger increases
in precipitation typically occur. El Niño has the potential to bring above-normal precipitation this
winter, especially over southern California. The most recent 30 days have seen near normal (essentially no)
precipitation across the state. For the next two weeks little precipitation is expected.
Forecast confidence for California and Nevada is high.
Rainfall over the small drought
area in northwestern Montana has been near to above normal over the past 30 days. For the next 5 days HPC
forecasts little precipitation over the region. The CPC 6-10 day and week 2 forecasts indicate near to above
normal precipitation for the region. The CPC monthly forecast for September depicts equal chances for a given
precipitation category while the CPC forecast for September-November suggests a slight tendency for below
normal precipitation. For these reasons the drought area over Montana is expected to show some improvement.
Over Washington State little precipitation is expected over the interior sections of the region for days 1-5,
while moderate to heavy precipitation is anticipated over the western coastal regions of Washington and Oregon.
Above-normal precipitation is forecast during the 6-10 day period while near normal precipitation is forecast
during the week 2 period. The CPC monthly forecast for September indicates equal chances for each of the
precipitation categories while the CPC seasonal forecast for September-November depicts below normal
precipitation for most of the region. For interior Washington the drought outlook specifies persist, and even
some eastward expansion of the drought area. The drought areas for coastal Washington and Oregon are specified
as some improvement due to short and medium range precipitation forecasts and to the fact that in an area that
normally has abundant precipitation drought improvement can occur even when below normal precipitation is
Forecast confidence for Montana, Washington, and Oregon is moderate.
The small areas of drought over
North Carolina and South Carolina depicted in the latest Drought Monitor are forecast to show improvement as
short, medium, and longer range forecasts suggest near or near to above normal precipitation over the region.
In addition El Niño composites for September-November indicate above normal precipitation for these
areas. It should be noted that September-November is a climatologically dry time of year for the region.
Forecast confidence for North and South Carolina is moderate.
Normal to above-normal rains for
southeastern Alaska during the first 2 weeks, and the seasonal trend toward lower temperatures and more
precipitation thereafter make the re-development of drought over Alaska unlikely.
For Hawaii, recent rainfall
associated with tropical systems has offered relief to some of the drought areas. Model forecasts suggest
additional tropical activity in the eastern Pacific. As these systems move westward additional rainfall is
possible over the region. Since confidence is low in any given system affecting Hawaii the drought outlook
indicates some improvement over the remaining areas of drought.
Forecast confidence for Hawaii is low.