Discussion for the Seasonal Drought Outlook
Tools used in the Drought Outlook included the
updated official precipitation outlook for October 2008, the long lead forecast
for October-December 2008, the HPC forecast of 1-5 day precipitation totals, 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, CFS precipitation foreasts for Oct-Nov-Dec,
the most recent U.K. Met office seasonal precipitation forecast for Oct-Nov-Dec, and climatology.
Tropical storm activity is climatologically
in sharp decline during the forecast period although the tropics will still have to be monitored for the possibility of late
season development. The tropical weather systems that affected the CONUS have chipped away at the edges of the drought areas
over Texas and the southeast. Unfortunately the heaviest precipitation from the tropical systems missed the core drought
areas for both of these regions. Currently the tropics have become much quieter and climtologically the tropical season is
winding down. For this reason the drought outlook is more pessimistic for the drought areas of the southeast and Texas.
However, late season tropical activity is not uncommon in active years so the tropics will have to be monitored.
In the short range,a strong trough is forecast to move from the east Pacific across the Pacific Northwest, the Great Basin to
the Plains. This will bring precipitation to northern California and parts of Northern Plains which should offer some relief to
those areas. Dryness has increased over southern Alabama leading to an area of D0 on the Drought Monitor so this region will
have to be watched for possible future drought development.
Eastern sections of the drought area over the southeast have seen
some recent relief due to frontal systems and an area of low pressure that moved from the Atlantic westward
across the Carolinas. Short range forecass indicate little to no precipitation for the region. 6-10 day and 8-14 day forecasts
lean toward near normal precipitaton for the area, while 30 day and 90 days forecasts have equal chances. The waning tropical
storm season and lack of indications for short term relief lead to a more pessimistic forecast for drought relief and so the
area of persist was extended southwestward.
Confidence for the Southeast and mid-Atlantic: Moderate
In the period after Hurricane Ike moved inland Texas has been dry.
Little precipitation is forecast over the region in the short and medium ranges, while longer range forecasts show equal
chances of above or below normal precipitation. With the tropical storm season winding down and soil moisture anomaly change
tools show worsening conditions, the drought area over interior Texas is forecast to persist.
Confidence for Texas: High
Over Southeastern Colorado and Southwestern Kansas little
precipitation has fallen ovee the last 7 days. Little precipitation expected in the short range and 6-10 day period, but
above normal precipitation is forecast for the 8-14 day period. Longer range forecasts indicate mostly equal chances of above
or below normal precipitation, although the CFS indicates a tendency for above normal precipitation and this is an area where
the CFS has shown some skill. For these reasons areas of some improvement are indicated over the mid-West.
Confidence for Southeastern Colorado and Southwestern Kansas: Moderate
Eastern sections of the upper Mid-west have seen some precipitation
over the last seven days. Some heavy precipitation is expected over the region over the next 5 days, especially over southern
sections of the drought areas. 6-10 day and 8-14 day forecasts have above normal precipitation for the region while 30 day and
90 day outlooks indicate equal chances of above or below normal precipitation. Soil moisture forecasts indicate a slight
tendency towards worsening conditions which conflicts with medium range outlooks of precipitation. For these reasons the
current drought otlook indciates some improvement over northern sections and improvement over southern sections.
Confidence for the Northern Plains: Moderate
Over the west little to no precipitation has fallen recently as
this is climatologically a dry time of year. Heavy precipitation is forecast over Northern California during the 1-5 day
period. The 6-10 day, 8-14 day and 30 day forecasts show above normal precipitation for Northern California
while the 90 day forecast indicates equal chances of above or below normal precipitation. Palmer drought indicator probability
forecasts show a high probability of improvement for Northern California. Over southern California precipitation is unlikley in
the short and medium ranges. The 30 day forecast over southern California is for equal chances while the 90 day forecast leans
toward dry for the region. For these reasons an area of improvement is indicated over Northern California, an area of some
improvment is shown for central California and an area of persist is progged for Southern California and Southern Nevada.
Confidence for the west: Moderate
In Hawaii, the eastern section of the Big Island and all of Lanai
are now in D1 drought. The current forecast indicates that these areas will persist.