Tools used in the U.S. Monthly Drought Outlook (MDO) included the official Climate Prediction Center (CPC)
updated temperature and precipitation outlooks for June 2015, various short- and medium-range forecasts and models
such as the 7-day precipitation totals from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC forecasts, week
3 and 4 experimental outlooks, the NAEFS precipitation outlooks, dynamical models (CFSv2), the 384-hour total precipitation
forecasts from several runs of the GFS, climatology, the latest official Drought Monitor analysis (released on May 28),
observed precipitation during the previous month, and initial conditions.
Thunderstorms across southern Florida have been largely isolated during mid-May; however, rainfall accumulations are likely to
increase as the rainy season begins in earnest. More widespread thunderstorm activity is anticipated during early June, with
the CPC 6-10 and 8-14 day outlooks indicting enhanced chances for above-median precipitation. The revised CPC monthly outlook
indicates equal chances for below, near, or above-median precipitation. Based on climatology and the shorter range forecasts,
drought removal is likely.
Forecast confidence for southern Florida is high.
Across the remainder of the Southeast and east-central U.S., dry, warm conditions promoted expansion of abnormal dryness (D0)
across parts of Mississippi, Alabama, and Georgia, with a small area of moderate drought (D1) developing over southern
Georgia. Additionally, widespread short term D0 was introduced across much of the southern Appalachians and eastern Tennessee
Valley on the May 26, 2015 U.S. Drought Monitor. In the short term, heavy precipitation (1 to locally 5 inches) is anticipated
along a frontal boundary extending from the eastern Tennessee Valley though the southern and central Appalachians. Widespread
rainfall exceeding an inch is forecast across the rest of the Southeast. This rainfall will help alleviate the developing dry
conditions, and may delay or halt additional drought development. The CPC 8-14 day outlook maintains a wet pattern across the
Ohio Valley and Southeast, while the revised monthly outlook indicates enhanced chances for above-median rainfall across the
Gulf Coast States. Given these outlooks, additional drought development across the east-central U.S. seems unlikely, and
removal of drought over southern Georgia is anticipated during June. Given the dry incipient conditions, however, any extended
period of dry, hot weather could promote rapid short term drought development during the Summer.
Forecast confidence for the Southeast and east-central U.S. is moderate.
Below normal precipitation and unseasonably warm weather during the past two weeks continued to promote drought degradation
and expansion across the Northeast. As of May 29. record low 7-day streamflow values were common from the mid-Atlantic states
through southern New England, and spotty showers and thunderstorms did little to boost soil moisture. Irrigation needs are
increasing to maintain good crop conditions. Current agricultural impacts remain relatively low given the dry conditions,
primarily due to cool Spring weather that slowed snow melt and evapotranspiration rates. Due to the dry Spring, conditions
have the potential to deteriorate rapidly during any episodes of Summer heat and dryness, with a climatology that favors soil
moisture loss. During the next several days, however, widespread heavy rainfall along and north of a slow moving frontal
boundary is expected to boost topsoil moisture and streamflows, with the heaviest accumulations (2 to 5 inches) over interior
New England. Accumulations of 1 to 3 inches are forecast across coastal areas of southern New England. These rains will
likely ease moderate drought and abnormal dryness across parts of New York, Hew Hampshire, far western Massachusetts, Vermont,
and Maine. Due to the large incipient precipitation deficits, however, the rains may not be sufficient to substantially
improve drought conditions across southern New England. A period of dry weather is anticipated in the wake of these early
June rains. Longer range forecasts are mixed, with high spread among dynamical model ensemble members. The CPC 8-14 day
outlook slightly favors above-median precipitation based on the ECMWF, while the CFS model persists abnormal dryness into
Weeks 3 and 4. Forecasts at all time scales favor above-median temperatures, which will promote high evapotranspiration
rates. This could make any improvements from the near term heavy rainfall short lived in the absence of significant additional
Forecast confidence for the Northeast is low.
An extremely active pattern, partly associated with El Niño related climate anomalies, continued across the central and
south-central U.S., promoting widespread heavy rainfall. These rains continued to erase drought conditions that have
persisted for 3 years, but also led to devastating and deadly flooding across parts of Texas and Oklahoma. Currently, only
small areas of long term (multi-year) D1 remain across the Plains. Significant rainfall also fell across the upper Midwest,
promoting drought reduction across Minnesota and Wisconsin. Additional widespread rainfall fell across the south-central U.S.
following the latest Drought Monitor period, exacerbating flooding and adding to massive runoff that is currently filling
reservoirs. These rains may further reduce the remaining drought areas across the central and southern Plains. During the
next several days, drier weather is forecast across much of Kansas and Oklahoma, but widespread rainfall is anticipated to
return to much of Texas, the northern Plains, and the upper Midwest. Both the CPC 8-14 day outlook and the revised monthly
outlook maintain a wet signal across most of the Plains and Midwest. Based on current conditions and these outlooks,
continued drought reduction is expected, and the Plains may be largely drought-free during much of June.
Forecast confidence for the Plains and upper-Midwest is high.
Widespread long term drought conditions continue across the western third of the Nation. Heavy precipitation and late season
snowfall brought improvements to parts of the central and southern Rockies, while dry, unseasonably warm weather promoted
additional short term drought development across the Northwest. A generally dry June climatology across the western U.S.
makes drought improvement unlikely, while extremely low mountain snow water content across the northern Rockies, Sierras,
and Cascades will limit any early summer reservoir recharge. Monsoon rainfall generally increases later in the summer, making
further improvements across New Mexico and southwestern Colorado unlikely. Based primarily on climatology and the lack of
snow cover, drought persistence and intensification are expected across most of the West during June. Additionally,
CPC 6-10, 8-14, and the revised June outlook all favor a continuation of hot, dry weather across the Northwest.
These conditions are anticipated to promote additional drought expansion across northwestern Washington and western Oregon.
A wetter climatology makes drought development across northern Montana less likely than areas further west.
Forecast confidence for the western third of the Nation is high.
Localized heavy thunderstorms eased abnormally dry conditions near San Juan, Puerto Rico, while rainfall deficits continued to
increase across other eastern areas of the island. Interior western portions of Puerto Rico have received more generous
rainfall during the past month. A dry signal becomes increasingly apparent during typical El Niño summers across the
Caribbean, with the dryness more prominent during August and September, as vertical shear inhibits organized tropical
convection. Dynamical models, including the GFS, CFS and ECMWF favor near to above-normal precipitation across the northern
Caribbean during the next several days, with a return to near normal or slightly below normal precipitation thereafter.
Experimental Weeks 3 and 4 forecasts from the CFS coupled model favor increasingly dry conditions, consistent with the low
frequency ENSO state. Based on ENSO climatology and initial conditions, drought persistence is anticipated, with development
possible in current D0 areas that have missed out on recent rainfall.
Forecast confidence for Puerto Rico is moderate.
Despite El Niño climate anomalies favoring wetness across Hawaii, persistence of existing drought areas is anticipated, as it
is a relatively dry time of year.
Forecast confidence for Hawaii is moderate.
Abnormal warmth promoted rapid snowmelt across south-central Alaska. Below normal precipitation was also observed during much
of May, and D0 conditions have expanded as a result. The revised CPC June outlook indicates enhanced chances for above median
precipitation across southern Alaska, with a dry signal favored over the north-central interior. Enhanced chances for
above-median temperatures are also anticipated, which increases the possibility for Summer drought development extant
D0 areas, however, wetness during April may slow the emergence of drought impacts, making June development specifically
Forecast confidence for Alaska is low to moderate.