Prognostic Discussion for Long-Lead Seasonal Outlooks 
NWS Climate Prediction Center College Park MD 
830 AM EST Thu Nov 16 2023 
 
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS 
 
El Niño conditions are currently observed, and equatorial sea surface 
temperatures (SSTs) are above average across the central and eastern Pacific 
Ocean. The El Niño Advisory remains in effect, and tropical Pacific atmospheric 
anomalies are consistent with El Niño. El Niño conditions are forecast to 
persist into December-January-February (DJF) 2023-2024, and El Niño is favored 
through Northern Hemisphere spring 2024 with chances gradually decreasing from 
the winter through the spring. A transition to ENSO-neutral is favored in 
May-July 2024. 
 
The DJF 2023-2024 Temperature Outlook favors above normal temperatures for 
Alaska, the west coast of the Contiguous United States (CONUS), the Northern 
Plains, the Ohio and Tennessee Valley regions, and the Mid-Atlantic. Above 
normal temperatures are more likely for western Alaska, parts of the west 
coast, and New England. Near normal temperatures are favored for the Central 
and Southern Rockies, and parts of the Central and Southern Plains. 
 
The DJF 2023-2024 Precipitation Outlook depicts below normal precipitation over 
southwestern Alaska and above normal precipitation over northern Alaska. Below 
normal precipitation is favored from the Northern Rockies to the Great Lakes 
and into the Ohio Valley. Above normal precipitation is favored over parts of 
the west coast, with a slight tilt toward above normal over parts of the 
central CONUS. The highest confidence for above normal precipitation is over 
the Southeast CONUS where teleconnections from El Niño are strongest. 
 
For both temperature and precipitation, areas depicted in white and labeled 
"EC" (Equal-Chances) are regions where climate signals  are weak or 
inconsistent, and thus equal odds for either above-, near- or below-normal 
seasonal mean temperatures and seasonal total precipitation amounts are 
favored. 
 
BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOKS 
Note: For Graphical Displays of the Forecast Tools Discussed Below See: 
http://www.cpc.ncep.noaa.gov/products/predictions/90day/tools/briefing 
 
CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS 
 
El Niño conditions are observed in both the atmosphere and ocean. In the last 4 
weeks, equatorial SSTs were above average across most of the Pacific Ocean and 
near-to-below average in the western Pacific Ocean. Above average SSTs 
strengthened near the date line and in the east central Pacific during the end 
of October and beginning of November. SST anomalies over the recent week were 
2.2 degrees C in the Niño1+2 region, and 1.8 degrees C in the Niño 3.4 region. 
 
Upper ocean heat anomalies for 180-100 degrees West have been increasing 
gradually since early October and positive subsurface temperature anomalies 
dominate much of the equatorial Pacific Ocean, and strengthened in the early 
parts of November around 170 degrees East to 130 degrees West. The above normal 
subsurface temperatures support persistence of the El Niño event. 
 
In the past 30 days positive Outgoing Longwave Radiation (OLR) anomalies are 
evident in the western Pacific near Indonesia, the Philippines, and Australia, 
while negative OLR anomalies extend from the date line into the eastern Pacific 
Ocean. Low level wind anomalies were westerly over much of the equatorial 
Pacific. Both of these are indicative of the El Niño event, and thus tropical 
Pacific atmospheric anomalies are consistent with El Niño. Recently, per CPC’s 
Global Tropical Hazards (GTH) Outlook, a strong Westerly Wind Burst (WWB) is 
observed in the low-level wind field northeast of Papua New Guinea, which may 
strengthen El Niño conditions, warming SSTs and enhancing convection east of 
the date line. 
 
The Madden Julian Oscillation (MJO) appears active as the Realtime Multivariate 
MJO (RMM) index recently increased in amplitude, however, given the strength 
and persistence of the El Niño event, El Niño remains the dominant influence on 
the forecast. 
 
Outside of the Equatorial Pacific, SST anomalies are broadly positive in the 
North Pacific and Atlantic basins. Positive SST anomalies are also present 
around the Alaskan coastline, with stronger anomalies along the southern and 
western coasts, and weaker but still positive anomalies along the northern 
coast. SST anomalies are also positive along the west coast of the U.S., in the 
Gulf of Mexico, and up much of the east coast. Negative and neutral to weakly 
positive SST anomalies are present off the coast of New England. 
 
PROGNOSTIC DISCUSSION OF SST FORECASTS 
 
The CPC Niño3.4 SST consolidation forecast shows a slight increase in the 
Niño3.4 index to 1.5 to 2 degrees C for November-December-January (NDJ), and a 
slight decrease to about 1.5 degrees C for DJF 2023-2024. Following DJF, a 
gradual decrease in SSTs is forecast until around April-May-June (AMJ) 2024, 
when the forecast reaches near ENSO neutral values. Forecast spread of the 
consolidation members from present to the AMJ 2024 season is low. Forecast 
plumes of the Niño3.4 index from the North American Multi-Model Ensemble (NMME) 
are similar, though the GFDL-SPEAR model forecasts more strengthening of the El 
Niño event though at least January 2024. Though the tools show a slight 
decrease in DJF 2023-2024, the aforementioned WWB may bring at least short term 
strengthening of El Niño. 
 
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS 
 
Dynamical model forecasts from the Copernicus (C3S) and NMME multi-model 
ensemble systems are used for the first three and six leads respectively, as 
well as individual model forecasts from the Climate Forecast System version 2 
(CFSv2) and European Centre for Medium Range Weather Forecasts (ECMWF) models 
as available. The objective, historical skill weighted consolidation that 
combines both dynamical and statistical forecast tools was also considered 
throughout all leads. The Calibration, Bridging and Merging (CBaM) tool 
anchored to the NMME forecasts and "bridged" to the Niño3.4 index is also 
utilized. 
 
El Niño impacts were considered given the strength and forecasted persistence 
of the El Niño event through the MAM 2024 season, and El Niño composites and 
correlation/regression of temperature and precipitation with the Niño3.4 region 
were used to determine typical El Niño impacts. Statistical guidance such as 
the global SST based Constructed Analog (CA) and long term temperature and 
precipitation trends  played a role in many of the outlook seasons, particularly 
beyond lead 6 when dynamical model guidance is unavailable. Coastal SST and sea 
ice anomalies are considered at early leads. 
 
PROGNOSTIC DISCUSSION OF OUTLOOKS - DJF 2023 TO DJF 2024 
 
TEMPERATURE 
 
The DJF 2023-2024 Temperature Outlook favors above normal temperatures for 
Alaska, the west coast of the CONUS, the Northern Plains, the Ohio and 
Tennessee Valley regions, the Mid-Atlantic, and Northeast. The greatest 
likelihood for above normal temperatures is forecast over western Alaska and 
parts of the west coast, partially supported by the above normal SST anomalies, 
and over New England, partially supported by above normal decadal trends . In 
addition to the SST anomalies and trends , the primary driver for the above 
normal temperature probabilities in DJF is the persisting El Niño event which 
is expected to lead to above normal temperatures along the northern parts of 
the CONUS, and dynamical model guidance that favors higher probabilities for 
above normal temperatures dipping southward along the west coast and into the 
Ohio and Tennessee Valley regions. The tilt toward above normal temperatures is 
maintained over Alaska, the west coast, northern parts of the CONUS, and 
Northeast until March-April-May (MAM) 2024 when El Niño impacts are expected to 
begin to wane, and higher uncertainty (EC) is introduced in the Northern 
Plains. It is notable that support from the CBaM model tilts more toward below 
normal temperatures in the Northern Plains throughout these seasons, despite 
the expected El Niño teleconnection. Though the season(s) may tilt above normal 
in the mean, some periods of cold may occur during winter and early spring. 
 
Near normal temperatures are favored for the Central and Southern Rockies and 
parts of the Central and Southern Plains in DJF 2023-2024, supported by a 
consolidation of dynamical and statistical models. Near normal temperatures are 
also expected for the Lower Mississippi Valley and parts of the Southeast and 
lower Mid-Atlantic coast in JFM 2024, and over the southeastern coast for FMA 
2024. These areas of near normal temperatures represent regions where there is 
interplay in the tools between expected impacts from El Niño, decadal trends , 
and dynamical model guidance, leading to a forecast of near normal. El Niño 
composites tilt weakly toward below normal in the Southeast during winter 
months, which is balanced by above normal trends  and a less confident but still 
above normal tilt in dynamical model forecasts, which overall supports near 
normal temperatures. 
 
Beginning in FMA 2024, below normal temperatures are favored over the Southern 
Plains, which are supported by El Niño teleconnections. This signal is 
persistent in tools through April-May-June (AMJ) 2024. 
 
From spring (May-June-July, MJJ) into summer and the remaining forecast leads, 
El Niño impacts are expected to decrease and decadal trends  become the primary 
driver of the forecasts. Predictability decreases in spring and more EC is 
depicted in the forecasts in the central CONUS. Above normal temperatures are 
favored over much of the CONUS through summer 2024 and shift toward the east 
coast by winter 2024-2025. Over Alaska, above normal temperatures are expected 
through AMJ 2024 given expected impacts from El Niño, and a mixture of EC and 
above normal temperatures are forecast over the state for the remainder of the 
forecast leads, mainly driven by trends . 
 
PRECIPITATION 
 
The DJF 2023-2024 Precipitation Outlook depicts below normal precipitation over 
southwestern Alaska and above normal precipitation over northern Alaska. The 
southwestern below normal area is consistent with expected El Niño 
teleconnections, and the northern above normal precipitation is supported by El 
Niño and decadal trends . Below normal precipitation is favored from the 
Northern Rockies to the Great Lakes, including parts of the Ohio Valley. Above 
normal precipitation is favored over parts of the west coast, with a slight 
tilt toward above normal over the central CONUS. Given a strong connection to 
El Niño over the Southeast CONUS, the highest confidence for above normal 
precipitation is over the Gulf States and along the east coast to South 
Carolina (60 to 70 percent), with probabilities decreasing toward New England. 
Confident above normal precipitation, with probabilities of at least 50 to 60 
percent, remains along parts of the Gulf coast through MAM 2024. El Niño 
impacts dominate forecast evolution through MAM 2024 for the precipitation 
outlook, and are modified based on other tools such as NMME, C3S, and decadal 
trends, as well as a consolidation of statistical and dynamical models . 
 
El Niño impacts are less pronounced in the forecasts beginning in AMJ 2024, and 
dynamical model guidance (where available) and decadal trends  become the 
primary considerations. A tilt toward above normal precipitation is depicted 
over parts of the southeastern CONUS and shifting northward to Ohio Valley to 
the Northeast in AMJ through JJA 2024, and re-emerges for parts of the eastern 
CONUS in winter 2024 as decadal trends  tilt toward above normal precipitation. 
Based mainly on decadal trends , below normal precipitation is favored over 
parts of the Northwest and Northern Plains, as well as in the Southern Plains 
from spring 2024 through early fall 2024. This area of favored below normal 
precipitation shifts toward the Central and Southern Plains in winter 2024. 
 
For Alaska, a tilt toward above normal precipitation is maintained over 
northern parts of the state through MAM2024 owing to both El Niño impacts and 
above normal precipitation trends . Below normal precipitation is favored for 
the southwest coast in winter 2024, mainly driven by expected El Niño impacts, 
before above normal precipitation begins to dominate the forecasts by spring 
2024 supported by NMME and C3S. From AMJ 2024 onward, long term precipitation 
trends dominate the forecast over Alaska. 
 
 
FORECASTER: Johnna Infanti 
 
The Climatic normals are based on conditions between 1991 and 2020, following 
the World Meterological Organization convention of using the most recent 3 
complete decades as the climatic 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. 
 
For a description of of the standard forecast tools - their skill- and the 
forecast format please see our web page at 
http://www.cpc.ncep.noaa.gov/products/predictions/long_range/tools.html 
(Use Lower Cas e Letters) 
Information on the formation of skill of the CAS forecasts may be found at: 
http://www.cpc.ncep.noaa.gov/products/Soilmst_Monitoring/US/Outlook/outlook.shtm 
l 
(use lowercase letters) 
Notes - These climate outlooks are intended for use prior to the start of their 
valid period.  Within any given valid period observations and short and medium 
range forecasts should be consulted. 
 
This set of outlooks will be superseded by the issuance of the new set next 
month on Dec 21 2023 
 
 
1991-2020 base period means were implemented effective with the May 20, 2021 
forecast release. 
$$