Prognostic Discussion for Monthly Outlook 
NWS Climate Prediction Center College Park MD 
830 AM EDT Thu Mar 20 2025 
 
 
30-DAY OUTLOOK DISCUSSION FOR APRIL 2025 
 
The April 2025 Monthly Outlook is made as current La Niña conditions are 
transitioning to neutral El Niño Southern Oscillation (ENSO) conditions. The 
most recent weekly Niño 3.4 sea surface temperature (SST) anomaly is at 0.0 
degrees Celsius. SST anomalies in the central Pacific Ocean remain negative, 
while SST anomalies in the eastern Pacific Ocean are now positive. Outgoing 
longwave radiation (OLR) anomalies are positive in the central tropical Pacific 
Ocean near the Date Line, indicating below-average convection and cloud cover, 
while negative OLR anomalies were observed over the Eastern Pacific. The 
pattern of suppressed convection over the central tropical Pacific Ocean is 
consistent with current La Niña conditions. Recently westerly low-level wind 
anomalies were observed over the east-central Pacific Ocean, where easterly 
wind anomalies are generally associated with La Niña conditions. Negative 
subsurface ocean temperature anomalies in the equatorial Pacific Ocean weakened 
significantly in recent weeks, and may be an indicator of a transition to ENSO 
neutral conditions. Dynamical model forecasts and the ENSO Outlook predict a 
transition to ENSO neutral conditions is likely by the end of April with a 
probability of around 75 percent. 
 
On subseasonal timescales, the Madden Julian Oscillation (MJO) is active in 
phase 3 with enhanced convection over the Indian Ocean. Dynamical models  
generally predict a rapid propagation of the MJO active phase across the 
Maritime Continent into the Western Pacific in the next week, with some 
uncertainty in the robustness of the MJO signal. Lagged composites indicate 
that this active MJO would decrease temperatures over the northern central 
Contiguous United States (CONUS) by early April, with potentially cooler 
temperatures over parts of the northwestern CONUS later in the month. Impacts 
of the MJO were generally considered in the April monthly outlook through 
dynamical model forecasts for the week 3-4 period that overlap with the first 
half of April. A Sudden Stratospheric Warming (SSW) event was observed recently 
over the Arctic, as the polar vortex was displaced and weakened. Impacts of an 
SSW are weaker when occurring late in the spring, compared to winter; however, 
significant cooling is generally observed over Alaska 30 to 60 days following 
the onset of the SSW, largely coinciding with the April Monthly Outlook. 
Although weaker impacts may be observed over the CONUS from a spring SSW, 
potential impacts include cooling of the northern central CONUS early in April 
and cooler temperatures for the Pacific coastal states through the month of 
April. 
 
The April temperature and precipitation outlooks were based primarily on 
dynamical model and statistical model forecasts. Dynamical model forecasts for 
the month of April are from the North America Multimodel Ensemble (NMME). In 
addition, the statistical consolidation (Stat CON) includes the following 
statistical tools: the Canonical Correlation Analysis (CCA), the Constructed 
Analog (CA), and an ENSO OCN tool, that combines the impact of ENSO, based on 
the CPC SST consolidation predicted median Niño 3.4 SST anomaly, with the 
Optimum Climate Normal (OCN) to represent decadal trends . Daily initialized 
forecasts from the Climate Forecast System (CFSv2) dynamical model for April 
and the most recent ECMWF and GEFS dynamical model forecasts for the week 3-4 
period that overlaps the beginning of the month of April were also considered. 
Recent boundary conditions, including coastal SSTs, and soil moisture 
anomalies, were additional factors considered. 
 
The April temperature outlook favors below normal temperatures for central 
western Mainland Alaska, consistent with dynamical model guidance from ECMWF 
and GEFS for early April as well as potential impacts of the recent SSW for 
30-60 days following the initial warming on March 9. The NMME model forecasts 
generally predict likely above normal temperatures across the CONUS, driven by 
dynamical model representations of decadal trends . Although the observed 
decadal trend is a significant predictable signal on seasonal timescales, 
observed trends  are not uniform across the CONUS. Above normal temperatures are 
favored across most of the southwestern CONUS into the southern Great Basin and 
Central Rockies, consistent with the Stat CON and CFSv2 model forecasts. Higher 
probabilities for above normal temperatures greater than 50 percent in parts of 
the Desert Southwest and South Texas are consistent with local temperature 
feedbacks to negative soil moisture anomalies. Equal chances (EC) of above, 
near and below normal temperatures are indicated for much of the Pacific Coast 
with weak probabilities favoring above normal temperatures for Southern 
California, in part due to possible impacts of an SSW in March, in addition to 
uncertainty in dynamical model forecasts for the first half of the month. Above 
normal temperatures are favored across the Southern Plains into the Gulf Coast 
region and northward up the Eastern Seaboard, consistent with CFSv2 forecasts. 
Elevated probabilities for above normal temperatures over parts of the 
Northeast are also supported by decadal trends . A large area of EC is indicated 
from the Pacific Northwest into the Northern Plains, the Great Lakes region, 
the Midwest, and the Central Mississippi Valley, where some periods of below 
normal temperatures are predicted by dynamical models  for early April, possibly 
related to an active MJO or a negative Arctic Oscillation associated with the 
current SSW. 
 
The April precipitation outlook slightly favors below normal precipitation for 
coastal areas of southwestern Mainland Alaska, supported by dynamical model 
forecasts from the NMME and by the Stat CON. Above normal precipitation is 
favored for parts of the Pacific Northwest, Columbia Basin, and Northern 
Rockies, consistent with the CFSv2 forecast and possible remaining impacts of 
La Niña. Below normal precipitation is favored for parts of Southern California 
and over a large area of the central and southern interior western CONUS 
eastward to western areas of the Central and Southern Plains, consistent with 
most dynamical model forecasts and the Stat CON. Below normal precipitation is 
also favored for much of the Gulf Coast region to the southern Atlantic coast, 
consistent with NMME and CFSv2 forecasts. Above normal precipitation is favored 
from the Central Mississippi Valley to the central Great Lakes region, 
supported by the CFSv2 and the International Multi-Model Ensemble (IMME). 
 
FORECASTER: Dan Collins 
 
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 Apr will be issued on Mon March 31 2025 
 
These outlooks are based on departures from the 1991-2020 base period. 
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