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FXUS05 KWBC 191231
PMD90D
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU OCT 19 2023
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS
AN EL NINO ADVISORY REMAINS IN EFFECT AS EL NINO CONDITIONS REMAIN STRONGLY IN
PLACE ACROSS THE PACIFIC OCEAN BASIN AND ITS INFLUENCE CONTINUES TO CONTRIBUTE
TO THE TEMPERATURE AND PRECIPITATION OUTLOOKS THROUGH THE UPCOMING WINTER
2023-2024 SEASON. IN FACT, ODDS FOR EL NINO CONDITIONS TO PERSIST THROUGH THE
NORTHERN HEMISPHERE SPRING 2024 ARE CURRENTLY FORECAST AT 80%.
THE NOVEMBER-DECEMBER-JANUARY (NDJ) 2023-2024 TEMPERATURE OUTLOOK DEPICTS
ELEVATED ODDS FOR ABOVE-NORMAL SEASONAL MEAN TEMPERATURES FOR ALASKA, THE FAR
WEST, THE NORTHERN TIER OF THE CONTIGUOUS U.S. AS WELL AS FOR THE OHIO VALLEY
AND MID-ATLANTIC. THE GREATEST LIKELIHOOD FOR WARMER THAN NORMAL TEMPERATURES
IS FOR PARTS OF ALASKA, THE PACIFIC NORTHWEST AND NEW ENGLAND.
FOR NDJ PRECIPITATION, ABOVE-NORMAL SEASONAL PRECIPITATION AMOUNTS ARE FAVORED
FOR THE NORTH SLOPE OF ALASKA, THE SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY,
SOUTHEAST AND SOUTHERN MID-ATLANTIC. DRIER-THAN-NORMAL CONDITIONS ARE MOST
LIKELY FOR AREAS IN THE PACIFIC NORTHWEST, NORTHERN ROCKIES, NORTHERN HIGH
PLAINS AND PARTS OF MICHIGAN.
AREAS DEPICTED IN WHITE AND LABELED "EC" (EQUAL-CHANCES) ARE REGIONS WHERE
CLIMATE SIGNALS ARE WEAK AND SO THERE ARE EQUAL ODDS FOR EITHER ABOVE-, NEAR-
OR BELOW-NORMAL SEASONAL MEAN TEMPERATURES AND SEASONAL TOTAL PRECIPITATION
AMOUNTS.
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
THE COUPLED OCEANIC AND ATMOSPHERIC OBSERVATIONS REFLECT EL NIñO CONDITIONS. IN
MID OCTOBER, SEA SURFACE TEMPERATURES (SSTS) ARE ABOVE AVERAGE ACROSS NEARLY
THE ENTIRE EQUATORIAL PACIFIC OCEAN. POSITIVE SST ANOMALIES GREATER THAN +2.5
DEGREES C ARE PRESENT IN THE EASTERN PACIFIC WITH ANOMALIES GENERALLY UNIFORM
OF +1 TO +2 DEGREES C FROM THE DATE LINE TO THE EAST-CENTRAL PACIFIC. THE
LATEST WEEKLY VALUES FOR THE NINO3.4 AND NINO4 SST INDICES ARE +1.5 AND +1.3
DEGREES C RESPECTIVELY WITH THE LATTER INDEX CONTINUING TO INCREASE.
A STRONG RESERVOIR OF WARMER THAN NORMAL WATER REMAINS OBSERVED AT DEPTH FOR
NEARLY THE ENTIRE PACIFIC BASIN WHEN VIEWING SUBSURFACE OCEAN WATER
TEMPERATURES ALONG THE EQUATOR. LARGEST POSITIVE OCEANIC HEAT CONTENT IS
LOCATED EAST OF 140 DEGREES W, BUT SUBSTANTIAL POSITIVE OCEANIC HEAT CONTENT
REMAINS PRESENT TO A DEPTH OF AT LEAST 150 M FOR THE MAJORITY OF THE REMAINDER
OF THE PACIFIC BASIN. THE WARMER THAN NORMAL WATER AT DEPTH SUPPORTS NOT ONLY
MAINTENANCE OF THIS EL NINO EVENT, BUT THE POTENTIAL FOR SOME FURTHER
STRENGTHENING OVER THE NEXT COUPLE OF MONTHS.
THE ATMOSPHERIC STATE IS DISPLAYING CHARACTERISTICS CONSISTENT WITH EL NINO. IN
AREAS OF THE CENTRAL PACIFIC, LOW-LEVEL WINDS WERE ANOMALOUSLY WESTERLY, WHILE
UPPER-LEVEL WINDS WERE ANOMALOUSLY EASTERLY. CONVECTION WAS ENHANCED AROUND THE
DATE LINE, STRETCHING TO THE EASTERN PACIFIC, JUST NORTH OF THE EQUATOR WITH
SUPPRESSED CONVECTION OBSERVED NEAR INDONESIA. THE EQUATORIAL SOUTHERN
OSCILLATION INDEX (SOI) AND THE TRADITIONAL STATION-BASED SOI ARE BOTH
SIGNIFICANTLY NEGATIVE.
LARGE AREAS OF ABOVE-NORMAL SEA SURFACE TEMPERATURES (SSTS) RESIDE IN BOTH THE
NORTH PACIFIC AND NORTH ATLANTIC OCEANS. MORE LOCAL COASTAL SSTS ARE
ABOVE-NORMAL FOR WESTERN AND NORTHERN COASTAL WATERS OF ALASKA AS WELL AS OFF
THE CALIFORNIA COAST.
PROGNOSTIC DISCUSSION OF SST FORECASTS
THE CPC NINO3.4 SST CONSOLIDATION FORECAST SHOWS A STEADY OR SLIGHT INCREASE IN
THE NINO3.4 SST INDEX ENTERING LATE AUTUMN AND EARLY WINTER 2023 AT A VALUE
NEAR OR JUST ABOVE +1.5 DEGREES C. THEREAFTER, A GRADUAL TREND TO A LESS
POSITIVE NINO3.4 SST ANOMALY IS DEPICTED REACHING ENSO NEUTRAL VALUES BY OR
NEAR THE AMJ 2024 SEASON. FORECAST SPREAD OF THE CONSOLIDATION MEMBERS FROM
PRESENT TO THE AMJ 2024 SEASON IS LOW.
THE NMME NINO3.4 SST INDEX FORECASTS ARE SIMILAR TO THAT WRITTEN ABOVE WITH
GENERALLY GOOD AGREEMENT WITH ONLY THE GFDL-SPEAR MODEL FORECASTING
CONSIDERABLY MORE STRENGTHENING OF THE EL NINO EVENT - PEAKING DURING DJF
2023-2024 WITH A VALUE SLIGHTLY ABOVE +2.0 DEGREES C.
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS
POTENTIAL COMMON IMPACTS ASSOCIATED WITH EL NINO ARE UTILIZED IN PREPARATION OF
THE OUTLOOK GIVEN THE CURRENT STRONG ONGOING EVENT. THIS INCLUDES STANDARD
TECHNIQUES SUCH AS COMPOSITE ANALYSIS AND REGRESSIONS ANCHORED TO NINO3.4 SST
IN BOTH DIAGNOSTIC AND PROGNOSTIC TERMS. GIVEN THE STRENGTH OF THE CURRENT EL
NINO EVENT AS REPRESENTED IN SURFACE AND SUBSURFACE OCEAN TEMPERATURE
OBSERVATIONS, EL NINO IMPACTS ARE CONSIDERED THROUGH THE MAM 2024 SEASON.
STATISTICAL GUIDANCE, INCLUDING THE GLOBAL SST BASED CA AND CCA FORECAST TOOLS,
PLAYED A CONSIDERABLE ROLE ALONG WITH LONG TERM TEMPERATURE AND PRECIPITATION
TRENDS (OCN) FOR MANY LEADS. DYNAMICAL MODEL GUIDANCE FROM THE NMME AND
COPERNICUS (C3S) MULTI-MODEL ENSEMBLE SYSTEMS ARE UTILIZED THROUGH MAM 2024. IN
ADDITION, OBJECTIVE, HISTORICAL SKILL-BASED CONSOLIDATION TOOLS CONTRIBUTE TO
THE OUTLOOK AND INCLUDE THE ENSO/OCN BASELINE GUIDANCE AND THE COMPLETE SUITE
OF STATISTICAL/DYNAMICAL FORECAST TOOL COMBINATIONS. COASTAL ANOMALOUS SSTS ARE
ALSO CONSIDERED DURING SOME FORECAST LEADS.
PROGNOSTIC DISCUSSION OF OUTLOOKS - NDJ 2023 TO NDJ 2024
TEMPERATURE
THE NDJ 2023-2024 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES FOR
ALASKA, THE FAR WEST, THE NORTHERN TIER OF THE CONTIGUOUS U.S. AS WELL AS FOR
THE OHIO VALLEY AND MID-ATLANTIC. THE GREATEST LIKELIHOOD FOR WARMER THAN
NORMAL TEMPERATURES IS FOR PARTS OF ALASKA, THE PACIFIC NORTHWEST AND NEW
ENGLAND. THE HIGH LIKELIHOOD FOR THE CONTINUATION OF A STRONG EL NINO EVENT
THROUGH SPRING 2024 AND SO ELEVATED ODDS FOR ASSOCIATED EXTRATROPICAL IMPACTS -
ON AVERAGE OVER MANY EVENTS - IS A PRIMARY DRIVER OF THE EVOLUTION OF THE
TEMPERATURE OUTLOOKS FROM NDJ 2023-2024 THROUGH THE MAM 2024. MULTIPLE TYPES OF
GUIDANCE IS UTILIZED TO ASSESS THE ENSO POTENTIAL IMPACTS IN PREPARATION OF THE
OUTLOOKS AND INCLUDED EL NINO COMPOSITES, ENSO REGRESSION / CORRELATION
INFORMATION, STATISTICAL
FORECAST TOOLS AND DYNAMICAL MODEL GUIDANCE.
THE COMBINATION OF ENSO (AS DEFINED AND PREDICTED BY THE CPC NINO3.4 SST
CONSOLIDATION) AND OCN SERVED AS THE INITIAL BASELINE FORECAST TO START FOR THE
OFFICIAL OUTLOOKS FROM NDJ 2023-2024 THROUGH MAM 2024. FAVORED ABOVE-NORMAL
TEMPERATURES CONTINUE ALONG THE NORTHERN TIER OF CONUS THROUGH THE FIRST 5
LEADS WITH A GRADUAL DECREASE IN COVERAGE AND RELAXATION OF PROBABILITIES IN
THIS HIGHLIGHTED AREA. THIS IS PRIMARILY EVIDENT IN THE NORTHERN PLAINS,
MIDWEST AND GREAT LAKES. IT IS RELATED TO GREATER UNCERTAINTY AS REPRESENTED BY
CONFLICTING SIGNALS FROM THE SUITE OF FORECAST TOOLS, POTENTIAL FOR IMPACTS
RELATED TO CHANGES IN THE STRATOSPHERE WHICH TEND TO OCCUR MORE OFTEN LATER IN
THE WINTER MONTHS/EARLY SPRING AND LONG TERM COLDER TEMPERATURE TRENDS ACROSS
THE NORTH CENTRAL CONUS ESPECIALLY IN FMA 2024.
FAVORED NEAR-NORMAL TEMPERATURES ARE FORECAST FOR PARTS OF THE ROCKIES,
SOUTHWEST AND SOUTH-CENTRAL PLAINS FOR DJF 2023-2024. THE STATISTICAL ONLY AND
TOTAL (STATISTICAL TOOLS AND NMME GUIDANCE COMBINED) CONSOLIDATION FORECASTS
PLAYED A CONSIDERABLE ROLE IN THIS FORECAST. INTERPLAY BETWEEN ENSO IMPACTS,
LONG TERM TEMPERATURE TRENDS AND DYNAMICAL MODEL GUIDANCE FROM THE NMME AND C3S
ENSEMBLE SYSTEMS RESULTED IN AN OBJECTIVE FORECAST WHERE NEAR-NORMAL
TEMPERATURES ARE MOST LIKELY FOR MUCH OF THIS AREA AND ALSO FOR THE LOWER
MISSISSIPPI VALLEY AND SOUTHEAST FOR JFM 2024. IT IS NOTEWORTHY THAT THE ECMWF
SEASONAL FORECAST FAVORS NEAR- TO BELOW-NORMAL TEMPERATURES FOR MUCH OF THE
INTERIOR CONUS DURING THE NDJ 2023-2024 THROUGH JFM 2024 SEASONS.
THERE IS GREATER CONSISTENCY AND A STRONGER SIGNAL FOR FAVORED BELOW-NORMAL
TEMPERATURES IN PART ASSOCIATED WITH EL NINO FOR THE SOUTHERN PLAINS FOR FMA
AND MAM 2024. THIS WOULD ALSO BE CONSISTENT WITH AN ASSUMED PERSISTENCE - NOT
FAR FETCHED - OF A FAVORED COLDER THAN NORMAL SIGNAL NOTED ABOVE IN THE JFM
2024 ECMWF FORECAST.
FOR ALASKA, THERE IS A STRONG SIGNAL FOR FAVORED ABOVE-NORMAL TEMPERATURES FOR
THE STATE DURING EL NINO EVENTS AND THIS IS HIGHLIGHTED IN THE OUTLOOKS FROM
NDJ 2023-2024 THROUGH AMJ 2024. TRENDS OF EARLIER SEA ICE MELT ALONG THE
WESTERN AND NORTHERN COASTS OF ALASKA INCREASE THE ODDS FOR NEARBY LAND AREAS
DURING AMJ 2024.
AS THE FORECAST SUITE EXTENDS INTO SUMMER AND AUTUMN 2024, THE COVERAGE OF
FAVORED ABOVE-NORMAL TEMPERATURES INCREASES SUBSTANTIALLY FIRST FOR AREAS IN
THE WESTERN AND EASTERN CONUS THROUGH MJJ 2024, AND LATER EXPANDS TO INCLUDE
THE MAJORITY OF THE FORECAST DOMAIN THROUGH AUTUMN 2024. THESE OUTLOOKS ARE
HEAVILY DRIVEN BY LONG TERM POSITIVE TEMPERATURE TRENDS.
PRECIPITATION
FOR THE NDJ 2023-2024 PRECIPITATION OUTLOOK, ABOVE-NORMAL SEASONAL
PRECIPITATION AMOUNTS ARE MOST LIKELY FOR THE NORTH SLOPE OF ALASKA, THE
SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY, SOUTHEAST AND SOUTHERN MID-ATLANTIC.
DRIER-THAN-NORMAL CONDITIONS ARE MOST LIKELY FOR AREAS IN THE PACIFIC
NORTHWEST, NORTHERN ROCKIES, NORTHERN HIGH PLAINS AND PARTS OF MICHIGAN.
SIMILAR TO THAT WRITTEN ABOVE FOR TEMPERATURE, THE EVOLUTION OF THE
PRECIPITATION OUTLOOKS THROUGH MAM 2024 ARE ANCHORED TO FIRST ORDER TO
POTENTIAL TYPICALLY OBSERVED IMPACTS DURING EL NINO EVENTS IN THE WINTER AND
SPRING SEASONS - ON AVERAGE OVER MANY EVENTS. IN ADDITION, CONSOLIDATION OF
BOTH STATISTICAL AND DYNAMICAL MODEL GUIDANCE (NMME, C3S) MODIFIED THE BASELINE
INITIAL EL NINO AND OCN FORECAST. THE AREA OF GREATEST CONFIDENCE IN THE
PRECIPITATION OUTLOOKS FROM NDJ 2023-2024 THROUGH FMA 2024 WITHIN THE FORECAST
DOMAIN IS OVERWHELMINGLY FOR AREAS ALONG THE GULF COAST AND SOUTHEAST CONUS
WHERE WETTER THAN AVERAGE CONDITIONS ARE FORECAST.
ELEVATED PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION IS ALSO FORECAST ALONG
THE EASTERN SEABOARD WITH COVERAGE EXPANDING NORTHWARD ALONG THE COAST FROM NDJ
2023-2024 TO JFM 2024 - WHICH IS STRONGLY SUPPORTED BY MOST DYNAMICAL MODEL
GUIDANCE. IN ADDITION, THE AREA OF FAVORED ABOVE-NORMAL PRECIPITATION IS
EXPANDED NORTHWARD TO THE CENTRAL AND NORTHERN PLAINS DURING FMA AND MAM 2024,
CONSISTENT WITH EL NINO IMPACTS, POSITIVE PRECIPITATION TRENDS IN SOME OF THIS
AREA AND DYNAMICAL MODEL GUIDANCE FROM THE NMME AND C3S SYSTEMS.
DESPITE A STRONG EL NINO EVENT HIGHLY LIKELY THIS UPCOMING WINTER AND SPRING,
THE NMME AND C3S DYNAMICAL MODEL GUIDANCE DEPICTS HIGH FORECAST SPREAD AND
SEASONAL PRECIPITATION OUTCOMES - BOTH IN SIGN (I.E., WET/DRY) AND LOCATION.
THIS IS QUITE DIFFERENT FROM SIMILAR FORECAST GUIDANCE PRECEDING THE 2015-2016
EL NINO EVENT. GIVEN THIS, THE FORECAST PROBABILITIES FOR EITHER ABOVE-NORMAL
OR BELOW-NORMAL SEASONAL PRECIPITATION ARE QUITE MODEST FOR THE WESTERN CONUS.
ELEVATED ODDS FOR ABOVE-NORMAL PRECIPITATION IS DEPICTED FOR PARTS OF
CALIFORNIA AND NEVADA DURING DJF 2023-2024 AND JFM 2024, WITH SLIGHTLY ELEVATED
PROBABILITIES EXTENDED ACROSS THE CENTRAL ROCKIES. THE BEST CONVERGENCE OF
ANCILLARY INFORMATION, FORECAST TOOLS AND MODEL GUIDANCE IS THE PRIMARY BASIS
FOR THE SELECTION OF THIS AREA.
FOR ALASKA, ABOVE-NORMAL PRECIPITATION IS MOST LIKELY FOR THE NORTH SLOPE OF
ALASKA DURING NDJ AND DJF 2023-2024 AND LATER THE EXTREME SOUTH CENTRAL COAST
IN THE JFM AND FMA 2024 SEASONS. THE SET OF OUTLOOKS FROM AMJ 2024 ONWARD ARE
PRIMARILY BASED ON LONG TERM PRECIPITATION TRENDS.
FORECASTER: JON GOTTSCHALCK
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 NOV 16 2023
1991-2020 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 20, 2021
FORECAST RELEASE.
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