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FXUS05 KWBC 211331
PMD90D
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EST THU DEC 21 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 IS EXPECTED TO CONTINUE THROUGH
THE NORTHERN HEMISPHERE WINTER, WITH A TRANSITION TO ENSO-NEUTRAL FAVORED
DURING APRIL-JUNE 2024.
THE JAN-FEB-MAR (JFM) 2024 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES
FOR ALASKA, THE WEST COAST OF THE CONTIGUOUS UNITED STATES (CONUS), AND FROM
THE NORTHERN ROCKIES ACROSS THE GREAT LAKES TO THE MID-ATLANTIC AND NORTHEAST.
THE HIGHEST ODDS FOR ABOVE-NORMAL TEMPERATURES ARE ACROSS THE NORTHWEST,
NORTHERN NEW ENGLAND, AND MUCH OF ALASKA. NEAR NORMAL TEMPERATURES ARE FAVORED
FOR PARTS OF THE CENTRAL AND SOUTHERN PLAINS AND PARTS OF THE SOUTHEAST. THE
OVERALL PATTERN FAVORING ABOVE-NORMAL TEMPERATURES ACROSS THE NORTHERN CONUS
WITH NEAR-NORMAL OR BELOW-NORMAL TEMPERATURES FAVORED FOR THE SOUTHERN TIER OF
THE CONUS PERSISTS THROUGH MAR-APR-MAY (MAM) 2024.
THE JFM 2024 PRECIPITATION OUTLOOK DEPICTS ELEVATED PROBABILITIES FOR
BELOW-NORMAL PRECIPITATION OVER SOUTHWESTERN ALASKA AND ELEVATED CHANCES OF
ABOVE-NORMAL PRECIPITATION OVER NORTHERN AND SOUTHEAST MAINLAND 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 MUCH
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-AVERAGE IN THE WESTERN PACIFIC OCEAN. ABOVE-AVERAGE SSTS STRENGTHENED IN
THE CENTRAL EQUATORIAL PACIFIC BUT COOLED IN EXTRATROPICAL PACIFIC NEAR THE
DATE LINE. SST ANOMALIES OVER THE RECENT WEEK WERE 1.5 DEGREES C IN THE NIñO1+2
REGION, AND 2.0 DEGREES C IN THE NIñO 3.4 REGION.
UPPER OCEAN HEAT ANOMALIES FOR 180-100 DEGREES WEST HAVE BEEN DECREASED FROM
MID-NOVEMBER INTO MID-DECEMBER, BUT REMAIN AMONG THE HIGHEST LEVELS OBSERVED IN
2023. POSITIVE (NEGATIVE) SUBSURFACE TEMPERATURE ANOMALIES DOMINATE MUCH OF THE
EQUATORIAL PACIFIC OCEAN EAST (WEST) OF THE DATE LINE, WITH LITTLE CHANGE TO
THE ANOMALIES AMPLITUDE IN THE EARLY PARTS OF DECEMBER. THE ABOVE NORMAL
SUBSURFACE TEMPERATURES SUPPORT PERSISTENCE OF THE EL NIñO EVENT.
POSITIVE OUTGOING LONGWAVE RADIATION (OLR) ANOMALIES (SUPPRESSED CONVECTION AND
PRECIPITATION) WERE EVIDENT AROUND INDONESIA. NEGATIVE OLR ANOMALIES (ENHANCED
CONVECTION AND PRECIPITATION) WERE OBSERVED AROUND THE DATE LINE, AND EXTEND
INTO THE EASTERN PACIFIC, REMAINING JUST NORTH OF THE EQUATOR. LOW-LEVEL
(850-HPA) WIND ANOMALIES WERE WESTERLY OVER THE EASTERN HALF OF THE EQUATORIAL
PACIFIC. UPPER-LEVEL (200-HPA) WIND ANOMALIES WERE EASTERLY ALONG THE
EQUATORIAL PACIFIC. AN ANOMALOUS ANTICYCLONIC COUPLET STRADDLES THE EQUATOR
AROUND THE EAST-CENTRAL PACIFIC.
THE MADDEN JULIAN OSCILLATION (MJO) APPEARS ACTIVE, 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 WESTERN AND SOUTHERN ALASKAN COASTLINES, THOUGH MUCH WEAKER THAN IN
PRIOR MONTHS. 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 AND THE
NORTHERN MID-ATLANTIC STATES.
SOME MODELING SYSTEMS ARE INDICATING THE POTENTIAL FOR A SUDDEN STRATOSPHERIC
WARMING DURING MID TO LATE JANUARY. UNCERTAINTY IS HIGH FOR SUCH EVENTS AS THEY
ARE RELATIVELY RARE, AND FORECASTING IMPACTS AT THE SURFACE ADDS ANOTHER LAYER
OF UNCERTAINTY. SHOULD STRATOSPHERIC WARMING OCCUR, INTRASEASONAL VARIABILITY
OVER SOME PARTS OF THE CENTRAL AND EASTERN CONUS COULD BE INCREASED.
PROGNOSTIC DISCUSSION OF SST FORECASTS
THE CPC NIñO3.4 SST CONSOLIDATION FORECAST SHOWS A STEADY SIGNAL FOR NINO3.4
STANDARDIZED ANOMALY VALUES ABOVE 1.0 DEG C THROUGH MAM, THEN A DROP TO NEAR
AVERAGE VALUES FOR THE REMAINDER OF THE OUTLOOK PERIOD. DATA FROM THE NMME
SUITE OF MODELS HAVE A SIMILAR PATTERN, THOUGH MANY OF THOSE MODELS HAVE
INDIVIDUAL MEMBERS INDICATING SOME VALUES LESS THAN -0.5 DEG C BY LATE IN THE
NORTHERN HEMISPHERE SUMMER OF 2024. THE OFFICIAL NOAA CPC ENSO PROBABILITIES
INDICATE THAT EL NINO IS FAVORED THROUGH MAM, WITH ENSO-NEUTRAL THROUGH JJA,
AND ABOUT EQUAL PROBABILITIES FOR ENSO-NEUTRAL AND LA NINA IN JAS 2024.
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.
EL NIñO IMPACTS WERE CONSIDERED GIVEN THE STRENGTH AND FORECAST 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. SNOW COVER WAS ALSO CONSIDERED FOR
THE NORTHERN PLAINS.
PROGNOSTIC DISCUSSION OF OUTLOOKS - JFM 2024 TO JFM 2025
TEMPERATURE
THE JFM 2024 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES FOR ALASKA,
THE WEST COAST OF THE CONTIGUOUS UNITED STATES (CONUS), AND FROM THE NORTHERN
ROCKIES ACROSS THE GREAT LAKES TO THE MID-ATLANTIC AND NORTHEAST. THE HIGHEST
ODDS FOR ABOVE-NORMAL TEMPERATURES ARE ACROSS THE NORTHWEST, NORTHERN NEW
ENGLAND, AND MUCH OF ALASKA. NEAR-NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF
THE CENTRAL AND SOUTHERN PLAINS AND PARTS OF THE SOUTHEAST. THE OVERALL PATTERN
FAVORING ABOVE-NORMAL TEMPERATURES ACROSS THE NORTHERN CONUS WITH NEAR-NORMAL
OR BELOW-NORMAL TEMPERATURES FAVORED BEING RESTRICTED TO THE SOUTHERN TIER OF
THE CONUS PERSISTS THROUGH MAR-APR-MAY (MAM) 2024. THE TREND SIGNALS ARE WEAK
DURING JFM FOR MUCH OF THE CONUS AND ALASKA, SO THE FORECAST IS LARGELY BASED
ON PATTERNS ASSOCIATED WITH EL NINO AND DYNAMICAL MODEL GUIDANCE. SOME OF THE
GUIDANCE IS INDICATING A WARMER SIGNAL ACROSS PORTIONS OF THE SOUTHEAST, SO
SOME OF THE AREAS WHERE NEAR-NORMAL TEMPERATURES WERE INDICATED LAST MONTH FOR
JFM ARE REMOVED. ODDS FOR ABOVE-NORMAL TEMPERATURES WERE LOWERED ACROSS THE
OHIO VALLEY AND LOWER GREAT LAKES DUE TO ADDITIONAL UNCERTAINTY ASSOCIATED WITH
THE POTENTIAL FOR AN SSW AND TO REFLECT RECENT MODEL GUIDANCE. NEAR-NORMAL
TEMPERATURES ARE FAVORED FOR THE CENTRAL AND SOUTHERN PLAINS AND PARTS OF
SOUTHEAST DURING JFM 2024, SUPPORTED BY A CONSOLIDATION OF DYNAMICAL AND
STATISTICAL MODELS. THESE AREAS OF FAVORED 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
ENHANCED NEAR-NORMAL PROBABILITIES. 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.
THE TILT TOWARD ABOVE NORMAL TEMPERATURES IS MAINTAINED OVER ALASKA, THE WEST
COAST, AND NORTHERN PARTS OF THE CONUS 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. THOUGH THE SEASON(S) MAY TILT ABOVE NORMAL
IN THE MEAN, SOME PERIODS OF COLD MAY OCCUR DURING WINTER AND EARLY SPRING DUE
TO INTRASEASONAL VARIABILITY.
DURING FMA THROUGH AMJ 2024, BELOW-NORMAL TEMPERATURES ARE FAVORED OVER PARTS
OF THE CENTRAL AND SOUTHERN HIGH PLAINS, REFLECTING THE ASSOCIATED IMPACTS OF
ENSO. THAT IMPACT IS SEEN IN REGRESSIONS OF TEMPERATURE AND NINO3.4 AS WELL AS
THE SST-CA.
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 LIKELY
THROUGH MJJ 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 JFM 2024 PRECIPITATION OUTLOOK DEPICTS ENHANCED PROBABILITY OF BELOW-NORMAL
PRECIPITATION OVER SOUTHWESTERN ALASKA AND ABOVE-NORMAL PRECIPITATION OVER
NORTHERN AND SOUTHEASTERN MAINLAND ALASKA. THE SOUTHWESTERN BELOW-NORMAL
PRECIPITATION AREA IS CONSISTENT WITH EXPECTED EL NIñO TELECONNECTIONS, AND THE
NORTHERN ABOVE-NORMAL PRECIPITATION AREA 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, WHERE THERE IS A STRONGER
SIGNAL FOR BELOW-NORMAL PRECIPITATION COMPARED TO THE PRIOR OUTLOOK FOR JFM.
ABOVE-NORMAL PRECIPITATION IS FAVORED OVER MUCH OF THE WEST COAST, ACROSS THE
GREAT BASIN, CENTRAL ROCKIES, AND INTO THE CENTRAL GREAT PLAINS TO REFLECT
LIKELY IMPACTS FROM EL NIñO AND THE POTENTIAL FOR SOUTHERLY SHIFTED STORM
TRACK. 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. PROBABILITIES OF AT LEAST 50 TO 60 PERCENT FOR
ABOVE-NORMAL PRECIPITATION, 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 THE OHIO VALLEY
TO THE NORTHEAST IN AMJ THROUGH ASO 2024, AND RE-EMERGES FOR PARTS OF THE
EASTERN CONUS BY 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 THROUGH FALL 2024.
FOR ALASKA, ABOVE-NORMAL PRECIPITATION IS FAVORED OVER NORTHERN PARTS OF THE
STATE THROUGH MAM 2024, OWING TO BOTH EL NIñO IMPACTS AND PRECIPITATION TRENDS.
BELOW-NORMAL PRECIPITATION IS FAVORED FOR THE SOUTHWEST COAST IN JFM 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 SON 2024 ONWARD, LONG TERM PRECIPITATION TRENDS WHICH FAVOR ABOVE-NORMAL
PRECIPITATION ACROSS MUCH OF NORTHERN MAINLAND ALASKA DOMINATE THE FORECAST
OVER ALASKA.
FORECASTER: MATTHEW ROSENCRANS
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 JAN 18 2024
1991-2020 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 20, 2021
FORECAST RELEASE.
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