578 

FXUS07 KWBC 161231
PMD30D
Prognostic Discussion for Monthly Outlook
NWS Climate Prediction Center College Park MD
830 AM EDT Thu Apr 16 2026


30-DAY OUTLOOK DISCUSSION FOR MAY 2026

The May 2026 Temperature and Precipitation Outlooks are based on the: North
American Multi-Model Ensemble (NMME) and International Multi-Model Ensemble
(IMME), consolidation (combination of statistical and dynamical model tools),
soil moisture influence and its constructed analog, and decadal trends. The
Madden-Julian Oscillation (MJO) strengthened during early April and dynamical
models have remained consistent since last week that a robust MJO propagates
eastward from the West Pacific to the Indian Ocean during the latter half of
April. This MJO evolution and its potential influence on the mid-latitude
circulation pattern was considered in the temperature outlook. ENSO-neutral
conditions are present with El Nino likely to emerge during May-June-July.



The NMME and IMME support an increased chance of above-normal temperatures for
the western contiguous U.S. (CONUS), much of the Great Plains, and Southeast.
The largest above-normal temperature probabilities (greater than 50%) are
forecast for the Pacific Northwest where the calibrated NMME and IMME have the
strongest warm signal and there is also support from the statistical tools. In
addition, the larger probabilities are consistent with the expectation for a
drier-than-normal May. Recent heavy precipitation has moistened topsoil from
eastern Oklahoma southward into central Texas. The GEFS and ECENS favor a
continuation of the wet pattern for these areas with an expansion eastward into
the Lower Mississippi Valley by the end of April. Due to the likelihood that
topsoil is neutral to wet heading into May and tools favor above-normal
precipitation for the month, above-normal temperature probabilities from the
dynamical models are reduced across much of the south-central CONUS. Farther to
the east, drier topsoil and the consolidation tool lead to an increased chance
of above-normal temperatures for the Southeast. The current West Pacific MJO
(phase 7) would favor an amplified 500-hPa trough developing over the eastern
CONUS by the end of April which may result in a relatively cool start to May
for the Midwest, Northeast, and Mid-Atlantic. However, if the MJO propagates
back to the Indian Ocean, then above-normal temperatures could return to these
areas later in May. Due to this expected variable temperature pattern during
the month and a weaker warm signal among the dynamical models, equal chances
(EC) of below, near, or above-normal temperatures are forecast from the Middle
and Upper Mississippi Valley east to the Mid-Atlantic and Northeast. Elevated
above-normal temperature probabilities are forecast for eastern Alaska.
However, the outlook hedged colder across southwestern Alaska with EC forecast
due to the Week 3-4 GEFS and ECENS favoring near to below normal early in the
month. Large negative SST anomalies led to the outlook leaning slightly on the
colder side along coastal southwestern Alaska and the Alaska Peninsula.



Based on the NMME, IMME, and consolidation, below-normal precipitation is
favored for parts of southeastern Alaska, the Pacific Northwest, and the Great
Basin. Conversely, these forecast tools support the outlook leaning on the
wetter side across southwestern Arkansas, southeastern Oklahoma, central to
eastern Texas, and most of Louisiana. Many of the dynamical models, especially
the ECMWF, along with trends favor a wetter May across the Southeast. However,
equal chances (EC) of below, near, or above-normal precipitation are forecast
for this region as the wet model signal was offset by a correlation between dry
April soil moisture and below-normal precipitation during May. As of mid-April,
soil moisture is below the 5th percentile throughout the Southeast and will
likely decline further during the next week with summerlike heat and an
increasing water demand. A large coverage of EC is also forecast across a
majority of Alaska and the lower 48 states due to high uncertainty at this time
lead with a monthly precipitation outlook along with low predictability in
forecasting anomalous convective precipitation throughout the central and
eastern CONUS.

FORECASTER: Brad Pugh

The climatic normals are based on conditions between 1991 and 2020, following
the World Meteorological Organization convention of using the most recent 3
complete decades as the climate reference period.  The probability anomalies
for temperature and precipitation based on these new normals better represent
shorter term climatic anomalies than the forecasts based on older normals.

An updated monthly outlook... for May will be issued on Thu April 30 2026

These outlooks are based on departures from the 1991-2020 base period.
$$