340
FXUS05 KWBC 151332
PMD90D
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EST THU FEB 15 2024
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS
WHILE EL NIñO CONDITIONS CONTINUE WITH EQUATORIAL SEA SURFACE TEMPERATURES
(SSTS) ABOVE AVERAGE ACROSS THE CENTRAL AND EASTERN EQUATORIAL PACIFIC OCEAN,
THE TOTAL SUBSURFACE OCEAN HEAT CONTENT ANOMALY ACROSS THE EQUATORIAL PACIFIC
HAS DROPPED TO NEAR ZERO, SIGNALING AN IMMINENT TRANSITION TO ENSO-NEUTRAL
CONDITIONS. THE ATMOSPHERIC CIRCULATION ACROSS THE GLOBAL TROPICS IS CONSISTENT
WITH THE ONGOING EL NIñO THOUGH, AND EL NIñO IS FORECAST TO IMPACT THE
CIRCULATION FOR THE MARCH-APRIL-MAY SEASON WITH A TRANSITION TO ENSO-NEUTRAL
CONDITIONS LATER IN THE SPRING AND EARLY SUMMER. LA NIñA CONDITIONS ARE
FORECAST TO LIKELY DEVELOP LATER IN SUMMER OR BY AUTUMN.
THE MARCH-APRIL-MAY (MAM) 2024 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL
TEMPERATURES ACROSS THE NORTHWESTERN CONTIGUOUS UNITED STATES (CONUS),
INCLUDING THE PACIFIC NORTHWEST, NORTHERN TO CENTRAL CALIFORNIA, PARTS OF THE
GREAT BASIN, AND THE NORTHERN ROCKIES. ABOVE-NORMAL TEMPERATURES ARE FAVORED
ACROSS THE NORTHERN CONUS, INCLUDING THE NORTHERN GREAT PLAINS, GREAT LAKES
REGION, AND NORTHEAST. THE HIGHEST FORECAST CONFIDENCE FOR ABOVE-NORMAL
TEMPERATURES IS FOR THE PACIFIC NORTHWEST, WHERE THE PROBABILITIES OF
ABOVE-NORMAL TEMPERATURES EXCEED 60 PERCENT. ABOVE-NORMAL TEMPERATURES ARE
FAVORED ACROSS ALASKA. EQUAL CHANCES (EC) OF ABOVE-, NEAR- OR BELOW-NORMAL
SEASONAL MEAN TEMPERATURES ARE INDICATED ACROSS THE SOUTHERN CONUS, WHERE EL
NIñO IMPACTS INCREASE THE CHANCES OF BELOW- AND NEAR-NORMAL TEMPERATURES, WHILE
DECADAL TIME SCALE TRENDS INCREASE THE LIKELIHOOD OF ABOVE-NORMAL TEMPERATURES.
THE MAM 2024 PRECIPITATION OUTLOOK FAVORS BELOW-NORMAL PRECIPITATION FOR PARTS
OF THE PACIFIC NORTHWEST AND NORTHERN ROCKIES, WHILE ABOVE-NORMAL PRECIPITATION
IS FAVORED FROM THE EASTERN CENTRAL PLAINS ACROSS THE MIDDLE AND LOWER
MISSISSIPPI VALLEY INTO THE MID-ATLANTIC AND SOUTHEAST, ASSOCIATED WITH
LINGERING IMPACTS DUE TO EL NIñO. ABOVE-NORMAL PRECIPITATION IS ALSO FAVORED
FOR PARTS OF NORTHWESTERN AND SOUTHERN MAINLAND ALASKA. BELOW-NORMAL
PRECIPITATION IS FAVORED FOR MUCH OF THE RIO GRANDE VALLEY. EC OF BELOW-, NEAR-
AND ABOVE-NORMAL TOTAL SEASONAL PRECIPITATION ARE DEPICTED BY REMAINING AREAS
IN WHITE.
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
ABOVE-AVERAGE SSTS PERSIST ACROSS THE EQUATORIAL CENTRAL AND EASTERN PACIFIC
OCEAN, WITH A SLIGHT WEAKENING OF POSITIVE ANOMALIES OVER THE EAST-CENTRAL
PACIFIC IN RECENT WEEKS. THE MOST RECENT WEEKLY SST ANOMALY FOR THE NIñO 3.4
REGION IS AT +1.7 DEGREES CELSIUS. EQUATORIAL SUBSURFACE TEMPERATURE ANOMALIES
(AVERAGED OVER 180-100W LONGITUDE AND 0-300 METERS DEPTH) ARE NEAR ZERO DEGREES
CELSIUS AFTER A DECREASE FROM A PEAK OF +1.5 DEGREES CELSIUS IN LATE NOVEMBER.
NEGATIVE SUBSURFACE TEMPERATURE ANOMALIES AT DEPTHS GREATER THAN 50 METERS HAVE
SPREAD FROM THE WESTERN PACIFIC EASTWARD ACROSS THE EAST-CENTRAL PACIFIC IN
RECENT WEEKS. IN THE LATEST FOUR-WEEK PERIOD, OUTGOING LONGWAVE RADIATION (OLR)
ANOMALIES AT THE TOP OF THE ATMOSPHERE ARE NEGATIVE TO THE WEST OF THE DATE
LINE NEAR THE EQUATOR AND EXTEND OVER THE EASTERN PACIFIC TO THE NORTH OF THE
EQUATOR. LOW-LEVEL (850-HPA) WIND ANOMALIES WERE NEAR LONG-TERM AVERAGES OVER
MOST OF THE EQUATORIAL PACIFIC IN RECENT WEEKS. UPPER-LEVEL (200-HPA) WIND
ANOMALIES WERE EASTERLY OVER THE EASTERN EQUATORIAL PACIFIC. THESE ATMOSPHERIC
AND OCEANIC CONDITIONS REFLECT A CONTINUATION OF EL NIñO INTO THE CURRENT
MONTH. THE MADDEN-JULIAN OSCILLATION (MJO) CONTINUES TO PROPAGATE WITH ACTIVE
CONVECTION ACROSS THE WESTERN PACIFIC OCEAN, CONSTRUCTIVELY INTERFERING WITH EL
NIñO. HOWEVER, DYNAMICAL MODEL FORECASTS INDICATE LARGE UNCERTAINTIES IN THE
REALTIME MULTIVARIATE MJO (RMM) INDEX AND A LIKELY DECREASE IN THE AMPLITUDE OF
THE MJO IN THE COMING WEEKS.
PROGNOSTIC DISCUSSION OF SST FORECASTS
THE CPC SST CONSOLIDATION FORECAST FOR THE NIñO 3.4 REGION PREDICTS RAPIDLY
DECREASING POSITIVE ANOMALIES IN SPRING WITH A NEAR ZERO MEDIAN ANOMALY BY THE
APRIL-MAY-JUNE (AMJ) SEASON. DYNAMICAL AND STATISTICAL MODELS ARE IN GOOD
AGREEMENT THAT A TRANSITION TO ENSO-NEUTRAL CONDITIONS IS LIKELY TO OCCUR
EITHER IN SPRING OR BY EARLY SUMMER. THE CPC ENSO OUTLOOK INDICATES THAT THE
PROBABILITY OF ENSO-NEUTRAL DURING AMJ IS NEARLY 80 PERCENT. THE PROBABILITY
OF A LA NIñA INCREASES TO GREATER THAN 50 PERCENT BEGINNING IN THE
JUNE-JULY-AUGUST (JJA) SUMMER SEASON. BY THE AUGUST-SEPTEMBER-OCTOBER (ASO)
THREE-MONTH PERIOD AND LATER INTO AUTUMN, THERE IS MORE THAN A 70 PERCENT
CHANCE OF LA NIñA.
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS
THE SEASONAL TEMPERATURE AND PRECIPITATION OUTLOOKS FOR MAM 2024 THROUGH MAM
2025 WERE BASED ON DYNAMICAL MODEL GUIDANCE THROUGH THE FIRST FIVE LEADS,
INCLUDING THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME). STATISTICAL MODELS,
SUCH AS THE ENSO-OCN TOOL THAT COMBINES THE PROBABLE TEMPERATURE AND
PRECIPITATION IMPACTS OF THE PREDICTED MEDIAN NINO 3.4 SST ANOMALY, AS FORECAST
BY THE CPC SST CONSOLIDATION, WITH THE DECADAL TEMPERATURE AND PRECIPITATION
TRENDS, WERE USED AT ALL LEADS. A SKILL-WEIGHTED CONSOLIDATION OF NMME
DYNAMICAL MODELS, A CONSOLIDATION OF STATISTICAL MODELS, AS WELL AS A FULL
CONSOLIDATION OF ALL AVAILABLE MODELS WERE PRIMARY TOOLS IN THE SEASONAL
TEMPERATURE AND PRECIPITATION OUTLOOKS. EL NIñO IMPACTS WERE CONSIDERED
EXPLICITLY, USING REGRESSION OF THE NIñO 3.4 INDEX ON TEMPERATURE AND
PRECIPITATION, FOR ONLY THE MAM 2024 OUTLOOK. BEGINNING IN ASO 2024 THROUGH THE
FINAL LEAD OUTLOOK FOR MAM 2025, THE IMPACTS OF LA NIñA WERE CONSIDERED, USING
TEMPERATURE AND PRECIPITATION SIGNALS FROM REGRESSION TO NEGATIVE VALUES OF THE
NIñO 3.4 INDEX.
PROGNOSTIC DISCUSSION OF OUTLOOKS - MAM 2024 TO MAM 2025
TEMPERATURE
THE MAM 2024 TEMPERATURE OUTLOOK PREDICTS ELEVATED PROBABILITIES OF
ABOVE-NORMAL TEMPERATURES FOR ALASKA AND ACROSS THE NORTHERN TIER OF THE CONUS,
SUPPORTED BY NMME FORECASTS, FORECAST TOOL CONSOLIDATIONS, AND TYPICAL IMPACTS
DUE TO EL NIñO. THE HIGHEST PROBABILITIES FOR ABOVE-NORMAL COVER NORTHWESTERN
PARTS OF OREGON AND MUCH OF WASHINGTON, WHERE THE TELECONNECTION TO EL NIñO HAS
ITS STRONGEST CORRELATION. WEAKER PROBABILITIES STILL FAVORING ABOVE-NORMAL
TEMPERATURES ARE FORECAST OVER THE NORTHERN PLAINS, DUE TO UNCERTAINTY IN THE
ARCTIC OSCILLATION (AO) PHASE. A PERSISTENT NEGATIVE PHASE OF THE AO WOULD LEAD
TO NEAR- OR BELOW-NORMAL TEMPERATURES IN THIS REGION. ABOVE-NORMAL TEMPERATURES
ARE LIKELY FOR MUCH OF THE GREAT LAKES REGION AND NORTHEAST WITH PROBABILITIES
EXCEEDING 50 PERCENT, WHERE THE GREAT LAKE SURFACE TEMPERATURES ARE ANOMALOUSLY
WARM AND DECADAL TRENDS IN THE NORTHEAST ARE STRONGLY POSITIVE. AS A RAPID
TRANSITION TO A NEUTRAL ENSO STATE IS PREDICTED, THE SEASONAL TEMPERATURE
OUTLOOKS FOR AMJ THROUGH JJA 2024 RELY PRIMARILY ON SIGNALS RELATED TO DECADAL
TRENDS. THE OUTLOOKS ARE SUPPORTED BY THE NMME FORECASTS THROUGH
JULY-AUGUST-SEPTEMBER (JAS) 2024 AND BY THE CONSOLIDATION OF AVAILABLE TOOLS
THROUGH ASO 2024. UNCERTAINTY FOR THE NORTHERN AND CENTRAL GREAT PLAINS
INCREASES THROUGH SPRING INTO SUMMER WHERE DECADAL TRENDS ARE WEAKER, WHILE
HIGHER PROBABILITIES FOR LIKELY ABOVE-NORMAL TEMPERATURES EXPAND ACROSS THE
WESTERN CONUS. ABOVE-NORMAL TEMPERATURES ARE FAVORED ACROSS MOST OF ALASKA
THROUGH MJJ 2024, AND PRIMARILY EASTERN MAINLAND ALASKA IN THE SUMMER SEASONS.
BY THE AUTUMN AND THE SEPTEMBER-OCTOBER-NOVEMBER (SON) 2024 OUTLOOK,
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES DECREASE FOR THE NORTHWESTERN AND
NORTH-CENTRAL CONUS, WHILE ELEVATED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES
INCREASE FOR NORTHERN MAINLAND ALASKA AND DECREASE FOR SOUTHERN MAINLAND
ALASKA, RELATED TO POTENTIAL IMPACTS OF A DEVELOPING LA NIñA. FOR THE CONUS,
AREAS FORECAST TO HAVE EC OF BELOW-, NEAR- AND ABOVE-NORMAL TEMPERATURES EXPAND
FROM THE NORTHWEST IN OCTOBER-NOVEMBER-DECEMBER (OND) 2024 DOWN THE WEST COAST
BY DECEMBER-JANUARY-FEBRUARY (DJF) 2024/25. BELOW-NORMAL TEMPERATURES ARE
SLIGHTLY FAVORED FOR PARTS OF THE PACIFIC NORTHWEST FOR THE DJF 2024/25 SEASON
THROUGH MAM 2025, DUE TO THE MORE LIKELY IMPACTS OF LA NIñA. FORECASTED AREAS
OF EC EXPAND INTO THE CENTRAL PLAINS, CENTRAL MISSISSIPPI VALLEY, AND OHIO
VALLEY IN THE WINTER SEASON AND LATER LEADS THROUGH MAM 2025. THESE LONGER LEAD
FORECASTS ARE SUPPORTED LARGELY BY THE ENSO-OCN FORECAST TOOL AND THE
STATISTICAL MODEL CONSOLIDATION.
PRECIPITATION
THE MAM 2024 PRECIPITATION OUTLOOK FAVORS BELOW-NORMAL PRECIPITATION FOR THE
PACIFIC NORTHWEST, CONSISTENT WITH POSSIBLE IMPACTS OF EL NIñO DURING THE FIRST
HALF OF THE SEASON. BELOW-NORMAL PRECIPITATION IS FAVORED FOR MUCH OF THE RIO
GRANDE VALLEY, WHILE ABOVE-NORMAL PRECIPITATION IS FAVORED FOR MUCH OF THE
EASTERN CONUS, SUPPORTED BY THE CONSOLIDATION OF AVAILABLE FORECAST TOOLS.
ABOVE-NORMAL PRECIPITATION IS FAVORED FOR NORTHWESTERN AND SOUTHERN MAINLAND
ALASKA, CONSISTENT WITH THE NMME CONSOLIDATION FORECAST. THROUGH SPRING INTO
SUMMER, AN AREA OF FAVORED ABOVE-NORMAL PRECIPITATION EXPANDS ACROSS MOST OF
MAINLAND ALASKA, LARGELY SUPPORTED BY THE NMME AND THE CONSOLIDATION OF
PRECIPITATION FORECAST TOOLS. BELOW-NORMAL PRECIPITATION IS SLIGHTLY FAVORED
ACROSS MUCH OF THE WESTERN HALF OF THE CONUS (EXCLUDING MOST OF CALIFORNIA AND
WESTERN AREAS OF THE GREAT BASIN AND SOUTHWEST) THROUGH JJA 2024, SUPPORTED BY
THE NMME AND THE CONSOLIDATION. THE AREAS WHERE ABOVE-NORMAL PRECIPITATION IS
FAVORED OVER THE EASTERN CONUS SHIFT EASTWARD TOWARDS THE ATLANTIC COAST BY MJJ
2024, AND THEN ARE CONFINED TO PARTS OF THE NORTHEASTERN CONUS BY SUMMER,
LARGELY CONSISTENT WITH SIGNALS RELATED TO DECADAL PRECIPITATION TRENDS.
BELOW-NORMAL PRECIPITATION IS FAVORED FOR PARTS OF THE SOUTHWEST FROM ASO 2024
THROUGH MAM 2025, AND FOR PARTS OF THE SOUTHEAST FROM OND 2024 THROUGH MAM
2025. ABOVE-NORMAL PRECIPITATION IS FAVORED FOR PARTS OF NORTHERN ALASKA IN THE
AUTUMN SEASONS AND FOR NORTHERN AND EASTERN INTERIOR ALASKA IN THE WINTER
THROUGH MAM 2025, CONSISTENT WITH THE STATISTICAL MODEL CONSOLIDATION.
ABOVE-NORMAL PRECIPITATION IS FAVORED OVER PARTS OF THE MIDWEST DURING THE
WINTER SEASONS. THE PRECIPITATION OUTLOOKS FOR AUTUMN THROUGH WINTER ARE
LARGELY RELATED TO POTENTIAL IMPACTS DUE TO LIKELY DEVELOPMENT OF LA NIñA.
FORECASTER: DAN COLLINS
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 CASE 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 MAR 21 2024
1991-2020 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 20, 2021
FORECAST RELEASE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page