90 Day Narrative

815 
FXUS05 KWBC 181331
PMD90D
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EST THU JAN 18 2018
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS
LA NINA CONDITIONS CONTINUE ACROSS THE EQUATORIAL PACIFIC OCEAN, AS REPRESENTED 
IN CURRENT OCEANIC AND ATMOSPHERIC OBSERVATIONS. THE OFFICIAL CPC ENSO FORECAST 
INDICATES THAT LA NINA IS LIKELY TO PERSIST THROUGH THE NORTHERN HEMISPHERE 
WINTER 2017-18, WITH A PREDICTED TRANSITION TO ENSO-NEUTRAL CONDITIONS DURING 
THE NORTHERN HEMISPHERE SPRING. ENSO-NEUTRAL CONDITIONS ARE FAVORED TO PERSIST 
THROUGH AT LEAST THE BOREAL SUMMER. 
THE FEBRUARY-MARCH-APRIL (FMA) 2018 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL 
TEMPERATURES ACROSS THE SOUTHERN TIER OF THE CONUS, WITH THE HIGHEST ODDS 
(GREATER THAN 60 PERCENT) FORECAST ACROSS THE SOUTHWEST. A SLIGHT TILT IN THE 
ODDS TOWARD ABOVE-NORMAL TEMPERATURES IS FORECAST ALONG THE EAST COAST. 
ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED FOR THE NORTH SLOPE OF ALASKA, THE 
WESTERN COAST OF ALASKA, AND THE ALEUTIANS. INCREASED CHANCES FOR BELOW-NORMAL 
TEMPERATURES DURING FMA ARE FORECAST FROM PARTS OF THE PACIFIC NORTHWEST EAST 
TO THE NORTHERN GREAT PLAINS, UPPER AND MIDDLE MISSISSIPPI VALLEYS, AND GREAT 
LAKES. BELOW-NORMAL TEMPERATURES ARE ALSO FAVORED FOR SOUTHEAST MAINLAND ALASKA 
AND THE ALASKA PANHANDLE. 
THE FMA 2018 PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES OF 
ABOVE-NORMAL PRECIPITATION AMOUNTS FOR PARTS OF THE PACIFIC NORTHWEST ALONG 
WITH NORTHERN AREAS OF THE GREAT BASIN, ROCKIES, AND GREAT PLAINS. INCREASED 
CHANCES OF ABOVE-NORMAL PRECIPITATION ARE ALSO FAVORED FROM THE GREAT LAKES 
SOUTH TO THE TENNESSEE VALLEY, ALONG WITH NORTHERN AND WESTERN MAINLAND ALASKA. 
BELOW-NORMAL PRECIPITATION IS FAVORED FOR PARTS OF THE SOUTHEAST, GULF COAST, 
CENTRAL AND SOUTHERN GREAT PLAINS, SOUTHWEST, AND SOUTHERN CALIFORNIA. THE MOST 
LIKELY AREA TO RECEIVE BELOW-NORMAL PRECIPITATION AMOUNTS IS SOUTHERN GEORGIA 
AND FLORIDA.
EQUAL CHANCES (EC) ARE FORECAST AMONG AREAS WHERE SEASONAL MEAN TEMPERATURES 
AND SEASONAL ACCUMULATED PRECIPITATION AMOUNTS ARE EXPECTED 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
OCEANIC OBSERVATIONS INDICATE THAT LA NINA CONDITIONS CONTINUED DURING THE PAST 
MONTHS AS EQUATORIAL SSTS ANOMALIES REMAINED NEGATIVE, AT APPROXIMATELY THE 
SAME MAGNITUDE, FROM THE DATE LINE TO THE SOUTH AMERICAN COAST. THE LATEST 
WEEKLY NINO-3.4 INDEX VALUE WAS -0.8 DEG C, AND THE NINO-3 AND NINO-1+2 INDICES 
WERE AT OR BELOW -1.0 DEG C DURING MUCH OF THE MONTH. NEGATIVE SUB-SURFACE 
TEMPERATURE ANOMALIES IN THE CENTRAL AND EAST-CENTRAL EQUATORIAL PACIFIC 
WEAKENED AT THE END OF THE MONTH AS ANOMALOUSLY WARM WATERS IN THE WESTERN 
PACIFIC AT DEPTHS GREATER THAN 100 M PROPAGATED EASTWARD TO APPROXIMATELY 140W. 
THE MOST RECENT ONI VALUE (OCTOBER  DECEMBER 2017), BASED ON SST DEPARTURES 
FROM AVERAGE IN THE NINO 3.4 REGION, IS -0.9 DEGREES C. 
THE ATMOSPHERIC CONDITIONS OVER THE TROPICAL PACIFIC OCEAN ALSO REFLECTED LA 
NINA, WITH SUPPRESSED CONVECTION NEAR AND EAST OF THE INTERNATIONAL DATE LINE 
AND ENHANCED CONVECTION TO THE NORTH OF INDONESIA. ALSO, THE LOW-LEVEL TRADE 
WINDS CONTINUED TO BE STRONGER THAN AVERAGE OVER THE WESTERN AND CENTRAL 
PACIFIC. 
THE ENHANCED PHASE OF THE MJO IS FORECAST TO PROPAGATE EAST ACROSS THE MARITIME 
CONTINENT DURING THE NEXT TWO WEEKS AND MAY REEMERGE OVER THE PACIFIC DURING 
EARLY FEBRUARY 2018. THIS EVOLUTION OF THE MJO MAY PLAY A ROLE IN THE 
CIRCULATION PATTERN AND TEMPERATURES ACROSS THE MID-LATITUDES OF NORTH AMERICA 
LATER IN FEBRUARY 2018. LONGER-TERM IMPACTS OF THE MJO ARE UNCERTAIN.
PROGNOSTIC DISCUSSION OF SST FORECASTS
THE CPC SST CONSOLIDATION FORECAST, WHICH INCLUDES THREE STATISTICAL FORECASTS 
ALONG WITH THE CFS, PREDICTS A TRANSITION FROM LA NINA TO ENSO-NEUTRAL 
CONDITIONS DURING SPRING 2018 WITH ENSO-NEUTRAL CONDITIONS FAVORED THEREAFTER. 
THE NORTH AMERICAN MULTI MODEL ENSEMBLE (NMME) ENSEMBLE MEAN FORECAST FOR THE 
NINO-3.4 SST ANOMALY IS SIMILAR TO THE PREVIOUS MONTH, THOUGH A LITTLE COOLER 
THROUGH APRIL, WITH A GRADUAL TRANSITION TO ENSO-NEUTRAL CONDITIONS AFTER THE 
NORTHERN HEMISPHERE WINTER. BASED ON THE LATEST OBSERVATIONS AND MODEL 
FORECASTS, THE OFFICIAL CPC/IRI ENSO OUTLOOK FAVORS ENSO-NEUTRAL CONDITIONS BY 
AMJ 2018.
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS
THE TEMPERATURE AND PRECIPITATION OUTLOOKS FOR FMA 2018 WERE BASED ON DYNAMICAL 
MODEL GUIDANCE AND STATISTICAL TOOLS THAT INCLUDE A CONSTRUCTED ANALOG BASED ON 
GLOBAL SST ANOMALY PATTERNS AND REGRESSIONS OF TEMPERATURE/PRECIPITATION ON THE 
CPC CONSOLIDATED NINO3.4 OUTLOOKS. DURING THE NEXT FOUR LEADS (MAM THROUGH JJA 
2018), THE FACTORS IN CREATING THE SUBSEQUENT OUTLOOKS WERE THE CALIBRATED 
PROBABILISTIC FORECASTS FROM THE NMME, TRENDS, THE CPC CONSOLIDATION, AND 
REGRESSIONS OF TEMPERATURE/PRECIPITATION ON THE CPC CONSOLIDATED NINO3.4 
OUTLOOKS. THE LATER OUTLOOKS THROUGH NEXT WINTER 2018-19 WERE BASED ON TRENDS 
AND THE CPC CONSOLIDATION FORECAST.
PROGNOSTIC DISCUSSION OF OUTLOOKS - FMA 2018 TO FMA 2019
TEMPERATURE
ABOVE-NORMAL TEMPERATURES DURING FMA 2018 ARE MOST LIKELY, WITH A GREATER THAN 
60 PERCENT CHANCE, TO BE OBSERVED ACROSS THE SOUTHWESTERN CONUS, WHICH IS 
CONSISTENT WITH REGRESSIONS OF TEMPERATURE ON LA NINA RELATED OCEANIC 
CONDITIONS, VARIOUS STATISTICAL TOOLS, DYNAMICAL MODEL FORECASTS, AND TRENDS. 
ABOVE-NORMAL TEMPERATURES, ALBEIT WITH LOWER PROBABILITIES, ARE ALSO FAVORED 
FOR THE GULF COAST STATES AND ALONG THE EAST COAST, BASED ON GOOD AGREEMENT 
AMONG THE DYNAMICAL MODELS. THE ODDS FOR ABOVE-NORMAL TEMPERATURES FOR THE 
AREAS FROM THE TENNESSEE VALLEY TO THE MID-ATLANTIC COAST, AND FOR THE CENTRAL 
CALIFORNIA COAST, ARE SLIGHTLY LOWER THAN WHAT WAS INDICATED FOR FMA 2018 FROM 
THE DEC 2017 RELEASE. MODELS OUTPUT AND CONSTRUCTED ANALOGS BASED ON SST 
PATTERNS INDICATE A SLIGHTLY COOLER PATTERN FOR SOME AREAS EAST OF THE ROCKIES, 
WHEN COMPARED TO LAST MONTH, SO THAT NEWER INFORMATION WAS INCORPORATED. LA 
NINA TEMPERATURE COMPOSITES DURING FMA SUPPORT BELOW-NORMAL TEMPERATURES ACROSS 
THE PACIFIC NORTHWEST, NORTHERN ROCKIES, NORTHERN GREAT PLAINS, AND UPPER 
MISSISSIPPI VALLEY. SOME STATISTICAL METHODS CONTINUE TO OFFER A COLDER 
SOLUTION ACROSS THESE AREAS COMPARED TO THE DYNAMICAL MODELS. BELOW-NORMAL 
TEMPERATURES ARE SLIGHTLY FAVORED FROM THE PACIFIC NORTHWEST TO THE GREAT LAKES 
REGION, GIVEN THE WELL-ESTABLISHED LA NINA CONDITIONS AND ASSOCIATED 
TELECONNECTIONS.  BELOW-NORMAL TEMPERATURES ARE ALSO FAVORED OVER SOUTHERN 
ALASKA, SUPPORTED BY MODEL OUTPUTS AND STATISTICALLY BASED RELATIONSHIPS WITH 
LA NINA.
THE TEMPERATURE OUTLOOK FOR MAM 2018 HAS MORE COVERAGE FOR ABOVE-NORMAL 
TEMPERATURES AND LESS FOR BELOW-NORMAL TEMPERATURES THAN FOR FMA. AREAS WHERE 
BELOW-NORMAL TEMPERATURES ARE NOW FAVORED ARE RESTRICTED TO THE PACIFIC 
NORTHWEST AND NORTHERN ROCKIES. TELECONNECTIONS FROM LA NINA TYPICALLY WEAKEN 
DURING THE SPRING AND A SHIFT TO ENSO-NEUTRAL CONDITIONS IS LIKELY TO OCCUR 
DURING THE SPRING. THE COOLER SHIFT, RELATIVE TO THE LAST RELEASE AS MENTIONED 
ABOVE, IS CONTINUED IN THE OUTLOOKS THROUGH AMJ 2018. THE TEMPERATURE OUTLOOKS 
FROM AMJ THROUGH JJA 2018 ARE BASED LARGELY ON THE CALIBRATED PROBABILITY 
FORECASTS FROM THE NMME ALONG WITH TRENDS. AN INCREASING CHANCE OF DROUGHT 
BECOMING ENTRENCHED OVER THE SOUTHWEST AND SOUTHERN PLAINS CONTRIBUTES TO 
ELEVATED ODDS FOR ABOVE NORMAL TEMPERATURES ELEVATED OVER THOSE REGIONS THROUGH 
JJA 2018. THE IMPACT OF SOIL MOISTURE ON TEMPERATURE IS MOST PRONOUNCED DURING 
THE WARM SEASON.
PRECIPITATION
THE FMA 2018 PRECIPITATION OUTLOOK IS BASED ON PRECIPITATION SIGNALS ASSOCIATED 
WITH LA NINA AND INPUT FROM THE SUITE OF NMME DYNAMICAL MODELS. PRECIPITATION 
TOOLS FAVOR A TIGHT GRADIENT BETWEEN AREAS FAVORED TO RECEIVE BELOW- AND 
ABOVE-NORMAL PRECIPITATION ACROSS THE SOUTHERN TO NORTHERN TIER OF THE CONUS, 
RESPECTIVELY. BASED ON GOOD AGREEMENT AMONG MOST OF THE DYNAMICAL MODEL 
FORECASTS INCLUDING THE NMME AND IMME, A SLIGHT TILT IN THE ODDS FOR 
BELOW-NORMAL PRECIPITATION COVERS PORTIONS OF CENTRAL CALIFORNIA AND ALL OF 
SOUTHERN CALIFORNIA. THIS FAVORED AREA FOR BELOW-NORMAL PRECIPITATION IS ALSO 
CONSISTENT WITH PRECIPITATION COMPOSITES FROM BACK-TO-BACK LA NINA WINTERS. THE 
AREA WHERE BELOW-NORMAL PRECIPITATION IS FAVORED DURING FMA 2018 IS SLIGHTLY 
SMALLER THAN THE AREA DEPICTED IN LAST MONTH'S FMA OUTLOOK, REFLECTING NEWER 
MODEL OUTPUT. THE HIGHEST PROBABILITIES (EXCEEDING 50 PERCENT CHANCE FOR 
BELOW-NORMAL PRECIPITATION) IN THE PRECIPITATION OUTLOOK FOR FMAARE FORECAST 
ACROSS SOUTHERN GEORGIA AND FLORIDA, AND PORTIONS OF THE SOUTHWEST. BASED ON 
THE LATEST NMME CALIBRATED PROBABILITY FORECAST, BELOW-NORMAL PRECIPITATION IS 
FAVORED ACROSS THE SOUTHERN HIGH PLAINS THROUGH MJJ 2018. 
COVERAGE OF FAVORED AREAS FOR ANOMALOUS PRECIPITATION DECREASE DURING THE 
SUMMER AS FORECAST CONFIDENCE DIMINISHES WITH A WEAKENING SIGNAL AMONG TOOLS 
AND CONVECTIVE PRECIPITATION BECOMES MORE DOMINANT. DURING JJA AND JAS 2017, 
BELOW (ABOVE)-NORMAL PRECIPITATION IS FAVORED FOR THE PACIFIC NORTHWEST 
(NORTHEAST), RELATED TO HISTORICAL TRENDS AND SIGNALS IN THE CPC CON.
FORECASTER: MATTHEW ROSENCRANS
THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1981 AND 2010, 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 FEB 15 2018
1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 
FORECAST RELEASE.
$$