Prognostic Discussion for Monthly Outlook 
NWS Climate Prediction Center College Park MD 
300 PM EDT Thu Apr 30 2026 
 
 
30-DAY OUTLOOK DISCUSSION FOR MAY 2026 
 
The updated May Temperature and Precipitation outlooks are based on the latest 
dynamical models, WPC temperature and precipitation forecasts during the first 
week of the month, the CPC 8-14 day temperature and precipitation outlooks, and 
the week 3-4 model output (valid May 15-28). Soil moisture was also a factor in 
the updated May outlooks. The Madden-Julian Oscillation (MJO) strengthened 
during early April with an eastward propagation over the Western Hemisphere. By 
late April, the MJO shifted east to Africa and the western Indian Ocean. A 
robust MJO overspreading the Indian Ocean and its potential influence later in 
May was a consideration in the updated temperature outlook. ENSO-neutral 
conditions are present with El Nino likely to emerge during May-June-July. 
 
Following an unusually warm early spring for the south-central and eastern 
contiguous U.S. (CONUS), a major pattern change was well underway by the end of 
April as a highly amplified 500-hPa trough has developed over eastern North 
America. A couple of strong cold fronts for this time of year are forecast to 
usher in cooler-than-normal temperatures from the Great Plains to the East 
Coast through the first ten days of the month. Unseasonably cool temperatures 
through at least early May results in the updated outlook leaning towards 
below-normal temperatures across parts of the Eastern Corn Belt, Great Lakes, 
and Northeast. The GEFS and ECENS depict the eastern North America trough 
deamplifying and progressing to the east by mid-May with anomalous mid-level 
ridging expanding to the Great Plains. The Week 3-4 GEFS and ECENS, valid from 
May 15-28, are in good agreement with a broad 500-hPa ridge and positive height 
anomalies throughout the lower 48 states. These model solutions also favor a 
flip from below to above-normal temperatures across much of the east-central 
CONUS during mid-May which would be consistent with the MJO currently entering 
the Indian Ocean. This predicted variable temperature pattern during May 
supports smaller probabilities (< 50%) for below and above-normal temperatures 
along with equal chances (EC) of below, near, or above-normal temperatures 
across the eastern third of the CONUS. Farther to the west, above-normal 
temperatures are more likely to prevail during most if not all of the month. 
The largest above-normal temperature probabilities (> 60%) are forecast for the 
Pacific Northwest with temperatures averaging 10 to 15 degrees F above normal 
during the first week of May. Probabilities are lower across the Desert 
Southwest as model solutions remain consistent that a couple of southern stream 
shortwave troughs cross this region early in the month. In addition to the 
predicted longwave pattern and dynamical model temperature tools, dry topsoil 
supports the increased chance of above-normal temperatures from the Oklahoma 
and Texas Panhandles north through western Kansas and Nebraska. Due in part to 
nearby below-normal sea surface temperature anomalies, the May outlook 
continues to slightly favor below-normal temperatures for southwestern Alaska 
and the Alaska Peninsula. Based on a model consensus, above-normal temperatures 
are slightly favored across northern to eastern Alaska. 
 
The updated May precipitation outlook relies primarily on the model 
precipitation forecasts through the first two weeks of the month. During the 
latter half of May, the GEFS and ECENS either diverge or depict weak signals  
for precipitation. A stationary front along with at least two shortwave troughs 
within the southern stream favor above-normal precipitation from Texas east to 
the Western Gulf Coast, Lower Mississippi Valley, and parts of the Southeast. 
Probabilities exceed 40% in portions of southeastern Texas, Louisiana, and 
southwestern Mississippi where the WPC 7-day qpf has around 2 inches of 
precipitation. Downstream of a 500-hPa trough axis that is forecast to persist 
through mid-May and consistent with the 8-14 day outlook, above-normal 
precipitation is slightly favored for eastern Maine. Although a number of tools 
lean on the wetter side for more of the Southeast and New England early in the 
month, high uncertainty during the later half of May precludes favoring 
above-normal precipitation. The large above-normal precipitation probabilities 
(> 60%) across southern New Mexico and the El Paso area are related to the 
likelihood that precipitation during the first week of May reaches the upper 
tercile for the month in a climatologically drier area. A dry start to the 
month and the expectation that anomalous 500-hPa ridging expands eastward to 
the north-central CONUS by mid-May favors below-normal precipitation across the 
Pacific Northwest, much of the Northern Rockies, Northern to Central Great 
Plains, and Upper Mississippi Valley. Due to weak and conflicting model 
guidance, EC is forecast throughout Alaska. 
 
 
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 Previous discussion released on April 16 below 
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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. 
 
The next monthly outlook...for Jun ... will be issued on Thu May 21 2026 
 
These outlooks are based on departures from the 1991-2020 base period. 
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