Prognostic Discussion for Monthly Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT Sat May 31 2025
30-DAY OUTLOOK DISCUSSION FOR JUNE 2025
The updated June 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 outlook (valid June 14-27). Soil moisture influence and its
constructed analog are also factors in the updated June outlook. During late
May, the Madden-Julian Oscillation (MJO) began to strengthen as the 200-hPa
velocity potential anomaly field became more coherent and wave-1 spatially with
anomalous upper-level divergence (convergence) over the Maritime Continent
(Atlantic and Africa). The ECMWF and GEFS model forecasts depict the Real-time
Multivariate MJO index gaining amplitude and moving through phases 6, 7, and 8
during early to mid-June. If the MJO continues to propagate eastward over the
Western Hemisphere, then the large-scale environment would become favorable for
tropical cyclone (TC) development initially across the East Pacific and then
expand to the Caribbean Sea later in June. Prior to this favorable MJO
response, recent dynamical model solutions and especially the GFS model have
depicted TC genesis across the western Caribbean Sea during early June.
A cut-off low near the northern Baja Peninsula will steer high anomalous
moisture, associated with Tropical Depression Alvin in the East Pacific,
northward to the Desert Southwest on June 1. An unusual wet start to June is
forecast for this region with WPC depicting widespread precipitation totals of
0.25 to 1 inch. Model solutions remain consistent that precipitation amounts
are likely to be enough to warrant large above-normal precipitation
probabilities (more than 60 percent) across Arizona to southern Utah since June
is a relatively dry month. This anomalous moisture, interacting with a front,
is also expected to result in heavy precipitation across much of Colorado and
northern New Mexico early in June, favoring enhanced above-normal precipitation
probabilities. Another area that is forecast to have a wet start to the month
is southeastern Kansas, southwestern Missouri, and Oklahoma with WPC
forecasting more than 3 inches of precipitation during the first week of June.
Therefore, above-normal precipitation probabilities are maximized for those
areas. Based on the WPC 7-day precipitation forecast, CPC 8-14 day outlook,
Week 3-4 outlook, and the constructed analog from soil moisture, above-normal
precipitation is favored for much of the Central to Southern Great Plains,
Middle to Lower Mississippi Valley, and Southeast. The increased chance of
above-normal precipitation for the Southeast is also consistent with the
expectation that the MJO would favor TC development across the western
Caribbean later in June. Conversely, precipitation tools at all time scales
support elevated below-normal precipitation probabilities extending from the
Pacific Northwest east to the Northern Great Plains This favored dryness is
related to a 500-hPa ridge that is forecast to persist either over or upstream
from these areas. Due to weak or conflicting signals among the model guidance,
equal chances (EC) of below, near, or above-normal precipitation are forecast
for the Midwest and Northeast. EC is also forecast for much of Alaska with only
a slight lean towards above-normal precipitation forecast across parts of
southeastern Alaska.
Since the initial June outlook was released on May 15th, model solutions have
remained consistent that a majority of the lower 48 states are more likely to
have a warmer-than-normal June. However, the one exception and where EC is
forecast includes parts of the Central to Southern Great Plains, Ozarks region,
and Lower Mississippi Valley, due to ongoing high soil moisture (above the 70th
percentile) and favored wetness during the next month. For the Southeast,
above-normal temperature probabilities are limited due to the expectation of a
wetter-than-normal June but the outlook leans on the warmer side with early to
mid-June favored to have above-normal temperatures. In contrast to the
likelihood of a warmer-than-normal June for most of the lower 48 states,
anomalous cold early in the month leads to an increased chance for below-normal
temperatures for Alaska. Later in the month, the ECENS and GEFS depict a
weakening of the persistent 500-hPa trough over Alaska which would lead to
moderating temperatures. Therefore, the updated June outlook only slightly
leans towards below-normal temperatures for Alaska. The highest forecast
confidence in the updated June outlook, with above-normal temperature
probabilities exceeding 50 percent, includes the Northeast and parts of the
West where temperatures are forecast to average 5 to 10 degrees F above normal
during the first week of the month and model solutions favor this anomalous
warmth continuing through at least mid-June.
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Previous mid-month discussion below
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The June 2025 Temperature and Precipitation Outlooks are based on the: North
American Multi-Model Ensemble (NMME) and International Multi-Model Ensemble
(IMME), consolidation (statistical and dynamical tools), soil moisture
influence and its constructed analog, and decadal trends . The Madden-Julian
Oscillation (MJO) remains weak and dynamical model spread is high on whether
the MJO may strengthen heading into June. Although the MJO is unlikely to
affect the mid-latitude circulation pattern during June, it will be closely
monitored as it could contribute to a more favorable environment for an early
season tropical cyclone in the Atlantic basin. ENSO-neutral conditions are
forecast to continue throughout June.
The highest forecast confidence in the temperature outlook is for above-normal
temperatures (probabilities greater than 60 percent) across the Southwest,
based on the calibrated NMME, warming influence from low soil moisture, and
consistent with decadal trends . The June outlook reflects the NMME and IMME
with their decreasing above-normal temperature probabilities farther to the
north over the West. Probabilities are also lower across much of Oklahoma and
northeastern Texas where high soil moisture (above the 90th percentile) would
have a cooling effect on surface temperatures in the coming weeks. In addition,
a constructed analog derived from soil moisture depicts a weak cold signal. The
NMME and the decadal trend support an increased chance of above-normal
temperatures for most of the East with the largest probabilities (exceeding 50
percent) forecast across the Florida Peninsula. Due to little or no signal in
the NMME and a more neutral trend, equal chances (EC) of below, near, or
above-normal temperatures are forecast for parts of the Northeast and Great
Lakes. Consistent with the NMME and decadal trends , above-normal temperatures
are more likely across the southern tier of Alaska with EC forecast for the
northern two-thirds of Mainland Alaska.
Based on the NMME, IMME, constructed analog from soil moisture, and trend,
below-normal precipitation is favored for parts of the Pacific Northwest,
northern Intermountain West, Great Basin, Rockies, and High Plains. The largest
below-normal precipitation probabilities (greater than 40 percent) extend from
Idaho and southwestern Montana southeastward to the southern High Plains where
the dynamical model output and statistical tools are in the best agreement. In
the climatologically drier areas of California and the Southwest, EC is
forecast. The constructed analog using sea surface temperatures depicts a wet
signal for the Southwest, implying an early, robust start to the Monsoon. This
would also be consistent with ongoing low soil moisture for the Southwest.
However, forecast confidence was not high enough at this time to lean towards
above-normal precipitation, given the lack of dynamical model support, but this
region will be reevaluated for the update released on May 31st. A broad area
with EC covers much of the Great Plains and Mississippi Valley due to a weak
signal among the precipitation tools along with large uncertainty in predicting
areas of anomalous convective rainfall at a half-month lead. A slight lean
towards above-normal precipitation is forecast for the East and parts of the
Great Lakes with the NMME, IMME, constructed analog from soil moisture, and
trend at least having a weak signal for a wetter-than-normal June. For Alaska,
above-normal precipitation is most likely across southeastern parts of the
state which is supported by the NMME and trend.
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 Jul ... will be issued on Thu Jun 19 2025
These outlooks are based on departures from the 1991-2020 base period.
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