Latest Seasonal Assessment -
During the past 30 days, widespread rainfall over the Southwest (robust monsoon), central and northern Plains, parts of the Mississippi Valley, and most of the eastern
third of the Nation (except portions of the Southeast) improved drought conditions across parts of Arizona, most of New Mexico, portions of the south-central Plains, and
the Tennessee Valley and Carolinas. Locally heavy rains (more than 4 inches within 24-hours) fell at several locations, including almost 8 inches north of Phoenix, AZ, and
over 13 inches near Islip, NY, producing flash flooding. Increased rainfall, partly due to tropical systems (Tropical Storm Iselle for Hawaii, Tropical Storm Bertha for
Puerto Rico), also diminished dryness, but mainly in Hawaii and less so in Puerto Rico. In contrast, drought conditions worsened across sections of the Northwest, Great
Basin, and parts of Texas. Abnormal dryness expanded across the Southeast and scattered areas of the north-central Plains and Midwest due to short term dryness.
Unseasonable heat over the Western States exacerbated ongoing drought conditions. Except for the formation of Bertha, suppressed convection over the Caribbean basin
generally persisted, with abnormal dryness and moderate drought remaining in southern and eastern Puerto Rico.
The seasonal drought outlook valid for August 21 through November 30, 2014 is based on analysis of initial conditions, short-, medium-, and long-range outlooks, and
climatology. Climate anomaly composites based on the forecast of a weak El Niño (65% chance this fall and early winter) were also considered, though these impacts
typically become more pronounced during the winter, after the end of this outlook period. Decreased soil moisture due to below normal rainfall increases the potential
for drought development across parts of the Southeast and Midwest, but subnormal temperatures have kept evaporative levels low. An anticipated wet pattern during late
August in these regions, however, may halt the development of drought and even erase abnormal dryness, so no areas of development were included here. Drought development
is favored across the Northwest based on below average precipitation the past 90-days and a tilt towards dryness and/or warmth in the 1-5, 6-10, and 8-14 day forecasts,
monthly and seasonal outlooks. Persistence is forecast for the Far West and Great Basin as September and October are climatologically dry and warm (and peak fire season),
especially in California, although November typically is the start of the wet season in the Pacific Northwest. A continued active monsoon across the Four Corners states
is anticipated to bring additional localized drought relief - with the moisture expected to spill northeastward into the Plains which brings favorable odds of above-normal
rainfall and drought amelioration. Equal chances of SON rainfall, changing to below-normal odds later in the year and into 2015, favors persistence of the remaining small
D1(L) in central Molokai, Hawaii (low reservoir), while a low frequency tropical convective climate signal (trending towards El Niño conditions) is anticipated to continue
a regime of suppressed convection across the Caribbean, favoring continued drought degradation across Puerto Rico.
Forecaster: D. Miskus
Next Seasonal Drought Outlook issued: September 18, 2014 at 8:30 AM EDT
Seasonal Drought Outlook Discussion