762
FXUS05 KWBC 211231
PMD90D
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU MAR 21 2024
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS
DURING MID-MARCH 2024, AN EL NIñO ADVISORY REMAINS IN EFFECT, BUT EL NIñO OCEAN
CONDITIONS ARE RAPIDLY WEAKENING AND ENSO NEUTRAL IS MOST LIKELY TO BE IN PLACE
BY THE END OF THE APRIL-MAY-JUNE (AMJ) SEASON. A LA NIñA WATCH IS ALSO IN
EFFECT AS LA NIñA CONDITIONS ARE FAVORED TO DEVELOP BY SUMMER AND CONTINUE
THROUGH AUTUMN 2024.
THE AMJ 2024 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL SEASONAL MEAN TEMPERATURES
FOR ALASKA, MUCH OF THE FAR WEST, THE SOUTHERN PLAINS AND THE EASTERN HALF OF
THE CONUS. GREATEST ODDS FOR WARMER THAN NORMAL TEMPERATURES IS SHOWN FOR
NORTHWEST ALASKA, THE PACIFIC NORTHWEST AND IN PROXIMITY TO THE GREAT LAKES. NO
AREAS OF FAVORED BELOW-NORMAL TEMPERATURES ARE FORECAST FOR SPRING 2024.
THE AMJ 2024 PRECIPITATION OUTLOOK FAVORS ABOVE-NORMAL SEASONAL TOTAL
PRECIPITATION AMOUNTS FOR PORTIONS OF SOUTHERN ALASKA AND FOR A REGION FROM THE
NORTHERN HIGH PLAINS SOUTHEASTWARD ACROSS THE CENTRAL PLAINS TO INCLUDE THE
SOUTHEAST AND MID-ATLANTIC. BELOW-NORMAL PRECIPITATION IS MOST LIKELY FOR PARTS
OF THE PACIFIC NORTHWEST AND SOUTHWEST.
EQUAL CHANCES (EC) ARE INDICATED FOR AREAS WHERE SEASONAL MEAN TEMPERATURES AND
SEASONAL TOTAL PRECIPITATION AMOUNTS ARE FAVORED TO BE SIMILAR TO
CLIMATOLOGICAL PROBABILITIES.
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 IS RAPIDLY WEAKENING AS EQUATORIAL PACIFIC OCEAN SEA SURFACE
TEMPERATURES (SSTS) CONTINUE TO COOL WITH ANOMALIES IN SST NEAR ZERO FOR PARTS
OF THE EQUATORIAL EASTERN PACIFIC. THE MOST RECENT WEEKLY VALUE OF THE NIñO3.4
SST INDEX IS +1.1 DEGREES C. BELOW THE SURFACE ALONG THE EQUATOR, THE 0-300
METER DEPTH TEMPERATURE ANOMALY (I.E., INTEGRATED HEAT CONTENT) IS NOW
NEGATIVE. SIGNIFICANT AREAS OF COOLER THAN NORMAL WATER TEMPERATURES ARE
OBSERVED AT DEPTH ACROSS MUCH OF THE BASIN, AND ESPECIALLY IN THE EASTERN
PACIFIC, WHERE A RESERVOIR OF ANOMALOUSLY COLD WATER IS PRESENT JUST BELOW OR
AT THE SURFACE FROM 120 W EASTWARD TO THE SOUTH AMERICA COAST WITH THE MAXIMUM
ANOMALY SURPASSING -6.0 DEGREES C.
ALTHOUGH THE OCEANIC INDICATORS FOR EL NIñO HAVE DECREASED IN THE PACIFIC
OCEAN, THERE DOES REMAIN SOME ATMOSPHERIC EL NIñO SIGNATURE, AND IT WILL LIKELY
TAKE SOME TIME FOR THIS RESPONSE TO COMPLETELY DISAPPEAR. FOR EXAMPLE, IN THE
PAST 30-DAY AVERAGE, SUPPRESSED CONVECTION REMAINED PRESENT FOR SOME PARTS OF
THE MARITIME CONTINENT, AND ENHANCED CONVECTION WAS PRESENT IN PROXIMITY TO THE
DATE LINE ALONG AND NEAR THE EQUATOR. MOREOVER, UPPER-LEVEL ANTI-CYCLONIC
CIRCULATIONS, SYMMETRIC ABOUT THE EQUATOR IN BOTH HEMISPHERES, ARE EVIDENT.
TRADE WINDS ARE INCREASING IN MAGNITUDE WITH WEAKENING EL NIñO CONDITIONS.
AN EXPANSIVE AREA OF BELOW-NORMAL SNOW COVER AND DEPTH IS PRESENT FROM THE
NORTHERN PLAINS EASTWARD TO THE GREAT LAKES AND NORTHEAST. ABOVE-NORMAL SOIL
MOISTURE IS PRESENT IN MANY AREAS THIS MARCH - INCLUDING AREAS IN CALIFORNIA
AND OTHER PARTS OF THE WEST AS WELL AS FOR THE EASTERN SEABOARD. DRIER THAN
NORMAL SOILS ARE EVIDENT NEAR THE FAR NORTHERN PLAINS, UPPER MIDWEST, GREAT
LAKES, OHIO VALLEY AND SOUTHWEST.
PROGNOSTIC DISCUSSION OF SST FORECASTS
FORECASTS OF THE NIñO3.4 SST INDEX FROM THE NMME ARE IN GOOD AGREEMENT FOR A
RAPID TRANSITION TO NEAR ZERO (I.E., NO ANOMALY) DURING AMJ 2024 AND
INCREASINGLY NEGATIVE ANOMALIES LESS THAN -1.0 DEGREES C BY ASO 2024. THE NMME
ENSEMBLE MEAN FORECAST ENTERS LA NIñA TERRITORY (LESS THAN -0.5 DEGREES C)
APPROXIMATELY DURING JULY 2024.
THE CPC NIñO3.4 SST CONSOLIDATION FORECAST FOLLOWS A SIMILAR TRAJECTORY AS THE
NMME ENSEMBLE MEAN CROSSES INTO LA NIñA TERRITORY AT A SIMILAR SEASON. THE CFS
AND THE CA MODELS SHOW THE MOST NEGATIVE VALUES AND POTENTIALLY A STRONGER LA
NIñA EVENT. THE CFS MODEL WOULD BE CONSIDERED AN OUTLIER AT THE CURRENT TIME
HOWEVER, AS IT PREDICTS A STRONG EVENT WITH A NIñO3.4 INDEX VALUE LESS THAN
-2.0 DEGREES C BY SON 2024.
THE OFFICIAL CPC ENSO OUTLOOK FAVORS ENSO NEUTRAL THROUGH THE MJJ SEASON WITH
LA NIñA FAVORED THEREAFTER INCREASING TO NEAR 85% LIKELIHOOD BY SON 2024.
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS
GIVEN SOME LIKELY REMAINING EL NIñO ATMOSPHERIC RESPONSE DURING APRIL 2024,
TYPICAL EL NIñO IMPACTS ARE CONSIDERED TO SOME DEGREE VERY EARLY IN THIS SET OF
OUTLOOKS (I.E., AMJ 2024). CURRENT ANOMALOUS SOIL MOISTURE AND SNOW COVER/DEPTH
ARE CONSIDERED AND CONTRIBUTED SUBSTANTIALLY TO THE OUTLOOK IN SOME LOCATIONS
DURING THE AMJ SEASON - PRIMARILY ACROSS AREAS OF THE NORTH WHERE WELL
BELOW-NORMAL SNOW COVER AND DEPTH ARE PRESENT AND IN PARTS OF THE MIDWEST AND
SOUTHWEST WHERE SOILS ARE DRY.
DYNAMICAL MODEL FORECASTS FROM THE NMME AND C3S MULTI-MODEL ENSEMBLE SYSTEMS
ARE UTILIZED, AS IS THE CALIBRATION, BRIDGING AND MERGING (CBAM) TOOL ANCHORED
TO THE NMME FORECASTS AND "BRIDGED" WITH THE NIñO3.4 INDEX - PRIMARILY FOR
TEMPERATURE OUTLOOKS. THE CA STATISTICAL TOOLS BASED ON SST AND SOIL MOISTURE
RESPECTIVELY ALONG WITH THE ENSO-OCN FORECAST TOOL THAT TARGETS IMPACTS FROM
ENSO AS PREDICTED BY THE CPC CONSOLIDATION NIñO3.4 SST FORECAST AND LONG TERM
TRENDS PLAYED A LARGE ROLE IN MANY OF THE OUTLOOKS.
LA NIñA IMPACTS ARE CONSIDERED IN THE OUTLOOKS FROM JJA 2024 THROUGH JFM
2024-2025. NATURAL ANALOGS FOR YEARS THAT UNDERWENT A TRANSITION FROM EL NIñO
TO LA NIñA DURING A SIMILAR PORTION OF THE SEASONAL CYCLE ARE ALSO EXPLORED.
PROGNOSTIC DISCUSSION OF OUTLOOKS - AMJ 2024 TO AMJ 2025
TEMPERATURE
THE AMJ 2024 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL SEASONAL MEAN TEMPERATURES
FOR MOST OF THE U.S. WITH THE EXCEPTION OF SOME AREAS OF THE SOUTHWEST U.S. AND
THE NORTHERN AND CENTRAL HIGH PLAINS. THE GREATEST ODDS OF ABOVE-NORMAL
TEMPERATURES IS FOR PARTS OF THE PACIFIC NORTHWEST, NORTHWEST ALASKA AND THE
GREAT LAKES REGION. THE AMJ OUTLOOK DOES NOT HIGHLIGHT ANY FAVORED AREAS FOR
BELOW-NORMAL SEASONAL MEAN TEMPERATURES.
RESIDUAL EL NIñO IMPACTS, POSITIVE TEMPERATURE TRENDS, ABOVE-NORMAL COASTAL
SSTS AND DYNAMICAL MODEL GUIDANCE FROM BOTH THE NMME AND C3S SYSTEMS SUPPORT
WARMER THAN NORMAL CONDITIONS IN THE PACIFIC NORTHWEST AS WELL AS MUCH OF THE
EASTERN CONUS. ODDS ARE HIGHEST IN THE GREAT LAKES AREA DUE TO ADDITIONAL
LIKELY IMPACTS FROM ANTECEDENT SURFACE CONDITIONS SUCH AS BELOW-NORMAL SNOW
COVER EXTENT AND DEPTH, DRY SOILS IN SOME AREAS, AND WARMER THAN NORMAL GREAT
LAKES. DRY SOILS ALSO RESULT IN A LOCAL MAXIMUM IN PROBABILITIES FOR
ABOVE-NORMAL TEMPERATURES FOR PARTS OF TEXAS AND NEW MEXICO. RESIDUAL IMPACTS
OF EL NIñO (POTENTIAL TROUGHING AND COOLER CONDITIONS) PRIMARILY EARLY IN THE
SEASON, AND CONFLICTING OR WEAKER CLIMATE SIGNALS RESULT IN A FORECAST OF EQUAL
CHANCES (EC) FOR AREAS IN THE SOUTHWEST AND NORTHERN AND CENTRAL HIGH PLAINS.
NEGATIVE TRENDS IN SEA ICE COVERAGE AND THICKNESS AND SO MORE OPEN WATER
EARLIER THAN NORMAL FOR OCEAN AREAS ALONG THE WESTERN AND NORTHERN COASTS OF
ALASKA AND STATISTICAL AND DYNAMICAL MODEL GUIDANCE FAVOR ABOVE-NORMAL
TEMPERATURES FOR MOST OF THE STATE OF ALASKA FOR AMJ 2024.
PROGRESSING THROUGH THE MJJ THROUGH JAS 2024 TEMPERATURE OUTLOOKS, ODDS FOR
ABOVE-NORMAL TEMPERATURES INCREASE ACROSS THE WESTERN AND SOUTHERN CONUS AS
THERE IS NEARLY UNANIMOUS AND CONSISTENT AGREEMENT FROM NMME AND C3S DYNAMICAL
MODEL GUIDANCE. THERE REMAINS MORE UNCERTAINTY FOR PARTS OF THE NORTH CENTRAL
U.S. THROUGH JJA 2024 SO EC IS FORECAST IN THIS AREA.
THE ANTICIPATED TRANSITION TO LA NIñA ENTERING SUMMER 2024 SUPPORTS GRADUALLY
INCREASING FORECAST COVERAGE AND ODDS FOR ABOVE-NORMAL TEMPERATURES FOR THE
MIDWEST DURING JAS 2024 AND ASO 2024. THEREAFTER, CONSIDERATIONS FOR THE SLOW
DEVELOPMENT OF TYPICAL LA NIñA IMPACTS (SUPPORTED BY LA NIñA COMPOSITES,
REGRESSIONS, AND STATISTICAL FORECAST TOOLS) DURING THE AUTUMN AND WINTER
MONTHS ARE THE REASONS FOR THE FORECAST EVOLUTION THROUGH FMA 2025. THIS
INCLUDES DECREASING ODDS FOR ABOVE-NORMAL TEMPERATURES AND THEN EC FOR MUCH OF
THE NORTHERN TIER OF THE U.S. THROUGH OND 2024 AND THE INTRODUCTION OF FAVORED
BELOW-NORMAL TEMPERATURES FOR THE PACIFIC NORTHWEST IN NDJ 2024-2025 THROUGH
MAM 2025. MOREOVER, ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR THE SOUTHERN HALF
OF THE U.S. AND ALONG THE EASTERN SEABOARD OVER THIS PERIOD.
FOR ALASKA, THE TRANSITION FROM EL NIñO TO FAVORED LA NIñA CONDITIONS RESULTS
IN DECREASING ODDS FOR ABOVE-NORMAL TEMPERATURES FROM WEST TO EAST THROUGH JAS
2024 WITH THE INTRODUCTION OF FAVORED BELOW-NORMAL TEMPERATURES FOR THE
SOUTHWEST PART OF THE STATE. THIS ORIENTATION IS ADJUSTED NORTH TO SOUTH
THROUGH OND 2024 WITH ABOVE-NORMAL TEMPERATURES MOST LIKELY FOR THE NORTHERN
PART OF THE STATE AND BELOW-NORMAL TEMPERATURES FAVORED FOR SOUTHERN COASTAL
AREAS.
PRECIPITATION
THE AMJ 2024 PRECIPITATION OUTLOOK FAVORS ABOVE-NORMAL SEASONAL TOTAL
PRECIPITATION AMOUNTS FOR THE SOUTHEAST, LOWER OHIO VALLEY, MID-ATLANTIC AND
PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS. RESIDUAL EL NIñO INFLUENCE, LONG
TERM POSITIVE PRECIPITATION TRENDS AS DEFINED BY OCN, DYNAMICAL MODEL GUIDANCE
FROM THE MAJORITY OF THE PARTICIPANT MODELS OF THE NMME AND C3S ENSEMBLE
SYSTEMS SUPPORT THIS FORECAST. BELOW-NORMAL PRECIPITATION IS FAVORED FOR PARTS
OF THE PACIFIC NORTHWEST DUE TO RESIDUAL EL NIñO INFLUENCE AND DYNAMICAL MODEL
GUIDANCE. DYNAMICAL AND STATISTICAL FORECAST TOOLS SUPPORT ELEVATED ODDS FOR
BELOW-NORMAL PRECIPITATION FOR AREAS IN THE SOUTHWEST.
THEREAFTER, THERE IS A RAPID TRANSITION TO STRONG DRY SIGNALS FROM MJJ THROUGH
ASO 2024 FOR THE EASTERN SOUTHWEST MONSOON REGION TO THE INTERIOR OF THE
CONTIGUOUS U.S. THIS IS CONSISTENT WITH DEVELOPING LA NIñA CONDITIONS AND
ASSOCIATED POTENTIAL IMPACTS AND IS SUPPORTED VERY STRONGLY BY STRONG SIGNALS
OF FAVORED BELOW-NORMAL PRECIPITATION FROM THE NMME AND C3S DYNAMICAL FORECAST
GUIDANCE. THE OUTLOOKS HIGHLIGHT RATHER LARGE FORECAST COVERAGE OF BELOW-NORMAL
PRECIPITATION FOR MANY AREAS OF THE WESTERN AND CENTRAL CONUS.
THEREAFTER, FAVORED DRIER THAN NORMAL CONDITIONS SHIFT TO THE SOUTHERN TIER OF
THE U.S., ASSOCIATED WITH A LA NIñA RESPONSE DURING THE COOL SEASON FROM SON
2024 THROUGH FMA 2025. OVER THE SAME FORECAST PERIOD, ABOVE-NORMAL
PRECIPITATION IS MOST LIKELY FOR THE PACIFIC NORTHWEST AND AREAS IN THE OHIO
VALLEY AND GREAT LAKES REGION WITH MAXIMUM COVERAGE AND ODDS DURING THE NDJ
2024-2025 AND JFM 2025 SEASONS RESPECTIVELY.
FOR ALASKA, ABOVE-NORMAL PRECIPITATION IS FAVORED DURING THE WARM SEASON
THROUGH JAS 2024. LATER IN THE SET OF OUTLOOKS, A SLIGHT TILT TOWARD
BELOW-NORMAL PRECIPITATION IS FORECAST FOR THE SOUTHEAST AREAS OF THE STATE
INCLUDING PORTIONS OF THE PANHANDLE FROM SON 2024 THROUGH NDJ 2024-2025.
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 APR 18 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