199
FXUS05 KWBC 161331
PMD90D
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 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 DEC 21 2023
1991-2020 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 20, 2021
FORECAST RELEASE.
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