Latest Seasonal Assessment -
The updated outlook shows little change from last month’s forecast across the West, with improvement expected in
the Northwest and northern Plains, but persisting drought in the arid Southwest. Moderate to heavy rains struck
the Northwest region in late September and early October, with snow in the higher elevations, and above-normal
precipitation is forecast to continue through the first half of October. Long-range forecasts show wetness for
October-December. Medium range and seasonal forecasts look dry for the Southwest. In the Upper Midwest, improvement
is expected to continue from Minnesota to Michigan. To the south, however, drought should persist from the
Maryland-Delaware area into northern portions of Georgia and Alabama. Tropical rains should lead to improvement
along the Gulf and Southeast Coasts, with more limited improvement expected in other portions of the drought region.
The drought affecting parts of southern New England may persist, while the drought in upstate New York should
improve. Hawaii is likely to see improvement.
Tools used in the Drought Outlook included
the official CPC long-lead precipitation outlook for October-December, the updated CPC forecast for
October, the four-month drought termination and amelioration probabilities, 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 (CAS) Constructed Analogue on Soil moisture.
Over the South, the updated forecast expands the
area of persisting drought from the mid-Atlantic into northern Alabama and Georgia. Negligible rain and
above-normal temperatures will worsen drought during the first 5 days of the period, and medium-range forecasts
show above-normal temperatures and normal rainfall for this region beyond day 5, as of October 2. At least one
model run, the 12Z GFS on October 2, is showing a deep trough over the East Coast and heavy rains in the
mid-Atlantic and New England states around October 10. As a result, short-term relief cannot be ruled out. La
Niña composites for October-December show below-normal rainfall from southern Pennsylvania into northern
Georgia and northeastern Alabama, with the strongest dry signal over the Virginia area during moderate to
strong La Niña episodes. Coastal improvement along the Gulf and Southeast is based mostly on tropical moisture
expected in October, as shown on the updated October precipitation outlook from CPC.
Medium-range forecasts show continued normal to
above-normal rainfall over the Minnesota to Michigan area, supporting continued drought improvement in this
region. To the east, the outlook for upstate New York is more uncertain. Climatology suggests good odds for
improvement in the Adirondacks, and GFS bias-adjusted rainfall forecasts indicate beneficial rains during week
1 and 2 across the state. In southern New England, prospects are very uncertain. The forecast depicts
persisting drought largely based on the dry weather expected during the first half of October, but the outlook
would be more positive for relief if the model runs subsequent to the above-mentioned GFS continue to show
heavy rains during the second week of October.
In the West, there was little change made to the
forecast released on September 20. Short, medium and long range forecasts support the wetness in the Northwest
and dryness in the Southwest. In Hawaii, climatology and the La Niña suggest drought improvement.