Tools used in the Drought Outlook included the official CPC long-lead precipitation outlook for July-September,
the drought termination and amelioration probabilities for September, various medium and short-range forecasts
and models such as the 6-10 day and 8-14 day forecasts, and the soil moisture tools based on the GFS model and
the Constructed Analogues for the season.
The June 15 Drought Outlook was updated on July 7 to
reflect the worsening situation in the Northern Plains and Upper Midwest. The July 4 Drought Monitor brought D1
drought into much of North Dakota as well as northwestern Minnesota and northern Wisconsin. With medium-range
forecasts showing above-normal temperatures for this region during at least the next 2 weeks, and generally light
rains for the Dakotas westward into Montana for the next 10 days, there will be a tendency for drought to continue
to expand. Latest model guidance shows that rainfall may be normal to above normal for Wisconsin and parts of
Minnesota, so the greatest risk for drought worsening and expansion appears to extend from Iowa and western,
central, and southern Minnesota westward into eastern Montana. For the longer term, the Constructed Analogue
from Soil moisture (CAS) forecast tool indicates a tendency for dryness to persist across most of this region
into autumn.
Elsewhere, the first 5 days of the period should see
heavy monsoon rains extending from the arid Southwest into Colorado, and these rains will extend eastward into
Kansas. The area of limited improvement shown in the updated Drought Outlook considers this shorter term outlook
plus the Southwest seasonal guidance for July-September rainfall shown in the CDC regression forecast issued in
June. The latter shows a weak tilt toward wetness for New Mexico and Colorado. More substantial drought alleviation
for the Southwest will likely need to wait until the 2006-07 snow season.
The other main change from the June Outlook is toward less optimism for the central Gulf Coast and Deep South, where
we have recently seen drought expansion in Alabama, Mississippi, and Louisiana. The rainfall outlook is very
uncertain for this region for most time frames beyond the first few days. The week-2 bias-corrected GFS forecasts
do show near normal rainfall for this region while longer-range forecast tools are mixed. Bottom line was a switch
to a depiction of some improvement. Longer and shorter range forecasts look more optimistic for the drought extending
from Georgia northward, so the forecast for improvement was continued from last month.
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