90 Day Narrative

275 
FXUS05 KWBC 151620
PMD90D
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EST THU NOV 15 2018
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS
THIS SECTION OF THE SEASONAL OUTLOOK MESSAGE SUMMARIZES THE FIRST FORECAST IN 
THE SET, THE DECEMBER-FEBRUARY (DJF) 2018-2019 SEASONAL OUTLOOK. DESCRIPTION OF 
THE SUBSEQUENT OUTLOOKS, CLIMATE FACTORS CONSIDERED, AND SPECIFIC FORECAST 
RATIONALE FOR ALL OUTLOOKS ARE PROVIDED IN THE LAST TWO SECTIONS OF THE 
MESSAGE. 
THE DJF 2018-2019 TEMPERATURE OUTLOOK CONTINUES TO FAVOR ABOVE-NORMAL SEASONAL 
MEAN TEMPERATURES FOR A GOOD PORTION OF THE FORECAST DOMAIN TO INCLUDE ALL OF 
ALASKA AND MUCH OF THE WESTERN AND NORTHERN CONTIGUOUS U.S. THE GREATEST 
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE INDICATED FOR THE PACIFIC 
NORTHWEST AND THE ALASKA PANHANDLE. FOR SEASONAL TOTAL PRECIPITATION AMOUNTS 
DURING DJF 2018-2019, THERE ARE MODESTLY ELEVATED CHANCES OF ABOVE-NORMAL 
PRECIPITATION FOR MOST OF THE SOUTHERN TIER OF THE CONTIGUOUS U.S., THE CENTRAL 
EASTERN SEABOARD, AND SOUTHERN ALASKA. BELOW-NORMAL PRECIPITATION IS MODESTLY 
FAVORED OVER THE GREAT LAKES AND PARTS OF THE MIDWEST.  
EQUAL CHANCES (EC) FOR ABOVE-, NEAR-, OR BELOW-NORMAL SEASONAL MEAN 
TEMPERATURES OR SEASONAL TOTAL PRECIPITATION AMOUNTS ARE INDICATED IN AREAS 
WHERE THE LIKELIHOOD OF THESE VARIABLES ARE FAVORED TO BE SIMILAR TO 
CLIMATOLOGICAL PROBABILITIES. THE REASONS FOR THIS CAN BE A COMBINATION OF 
WEAKLY DEFINED OR NON-RELIABLE CLIMATE FACTORS AS WELL AS CONSIDERABLE SPREAD 
IN FORECAST TOOL SOLUTIONS.
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
STARTING WITH OCEAN CONDITIONS, WE ARE STILL OFFICIALLY IN ENSO-NEUTRAL 
CONDITIONS THROUGH EARLY NOVEMBER AND THE EL NINO WATCH REMAINS IN PLACE. SEA 
SURFACE TEMPERATURES (SSTS) ARE ABOVE-NORMAL ACROSS MOST OF THE EQUATORIAL 
PACIFIC BASIN, GENERALLY RANGING FROM +0.5 - +1.0 DEGREES C. THE MOST RECENT 
WEEKLY VALUES OF THE NINO4 AND NINO3.4 INDICES ARE NOW +0.9 AND +0.8 DEGREES C 
RESPECTIVELY. SUBSEASONAL VARIABILITY OF EQUATORIAL SST ANOMALIES HAS BEEN 
MODULATED BY MJO ACTIVITY OVER THE PAST SEVERAL WEEKS. A STRONG DOWNWELLING 
OCEANIC KELVIN WAVE INITIATED AS A RESULT OF WESTERLY WIND BURST EVENTS 
CONTINUES TO SHIFT EASTWARD ACROSS THE PACIFIC BASIN AT DEPTH. THE EQUATORIAL 
UPPER-OCEAN HEAT CONTENT REMAINS ELEVATED AND FAVORS EL NINO CONDITIONS HEADING 
INTO WINTER. SPECIFIC NINO3.4 SST FORECASTS ARE REVIEWED IN THE SECTION BELOW.
THE ATMOSPHERIC CONDITIONS ASSOCIATED WITH A DEVELOPING EL NINO EVENT REMAIN 
MODEST AT BEST. THE PRESENCE OF WESTERLY WIND ANOMALIES HAS BEEN HIGHLY 
DEPENDENT UPON THE PHASE OF THE SUBSEASONAL MJO SIGNAL. PERHAPS MORE CONCERNING 
FROM THE PERSPECTIVE OF TROPICAL-EXTRATROPICAL TELECONNECTIONS IS THE ABSENCE 
OF ANY PERSISTENT CONVECTIVE RESPONSE OVER THE CENTRAL EQUATORIAL PACIFIC TO 
ABOVE-NORMAL SSTS. STANDARDIZED 200-HPA HEIGHT ANOMALY FORECASTS FROM THE 
CFSV2, FOR EXAMPLE, SHOW A RELATIVE WEAKNESS IN POSITIVE HEIGHT ANOMALIES 
SOUTHEAST OF HAWAII DURING DECEMBER, QUITE THE OPPOSITE OF THE EXPECTED EL NINO 
SIGNAL. 
TURNING TO CURRENT TERRESTRIAL CONDITIONS, WE NOTE MUCH ABOVE-NORMAL SOIL 
MOISTURE ANOMALIES FROM TEXAS TO THE MIDWEST, EASTWARD TO THE GREAT LAKES, 
MID-ATLANTIC AND PARTS OF THE NORTHEAST, WHILE DROUGHT CONDITIONS PERSIST 
ACROSS MANY AREAS OF THE WEST. AS WE ARE ENTERING THE LATE AUTUMN AND WINTER 
MONTHS, SOIL MOISTURE CONDITIONS, ALTHOUGH NEAR THE 99TH PERCENTILE IN MANY 
AREAS, IS NOT EXPECTED TO CONTRIBUTE ANY SIGNIFICANT IMPACT TO THE CLIMATE 
CONDITIONS OVER THE NEXT SEVERAL MONTHS SINCE INCIDENT SOLAR RADIATION IS NEAR 
ITS MINIMUM IN THE ANNUAL CYCLE. SNOW COVER ANOMALIES HAVE BEEN POSITIVE OVER 
MUCH OF THE NORTHERN CONUS AND SOUTHERN CANADA. IT IS NOT CLEAR, HOWEVER, THAT 
THIS PLAYS A SUBSTANTIAL ROLE IN MODULATING THE CLIMATE IN THE COMING MONTHS.   
   
PROGNOSTIC DISCUSSION OF SST FORECASTS
FORECASTS OF THE NINO3.4 SST ANOMALY REMAIN SIMILAR TO FORECASTS ISSUED LAST 
MONTH. THE CPC CONSOLIDATION NINO3.4 SST ANOMALY FORECAST MAINTAINS ITS RECENT 
PREDICTIONS OVER THE PAST SEVERAL MONTHS WITH A PEAK DURING NDJ 2018-2019 OF 
JUST UNDER +1.0 DEGREE C AND THEN SLOWLY DECREASES OVER THE COURSE OF THE 
WINTER AND SPRING MONTHS OF 2019. ONE TREND THAT HAS EMERGED THIS MONTH IS THAT 
IN ADDITION TO THE CCA FORECAST, THE MARKOV MODEL AND TO SOME EXTENT THE 
SST-CA, NOW FAVOR THE PERSISTENCE OR GROWTH OF POSITIVE NINO3.4 ANOMALIES 
DURING 2019. THIS IS A TREND THAT WILL BE CLOSELY WATCHED OVER THE COMING 
MONTHS. THE NMME NINO3.4 SST ANOMALY MODEL GUIDANCE ALSO HAS REMAINED 
CONSISTENT OVER THE PAST FEW MONTHS AND CONTINUES TO INDICATE A SLIGHTLY 
STRONGER EVENT (ENSEMBLE MEAN PEAKING AND PERSISTING BETWEEN +1.0 - +1.2 
DEGREES C) DURING THE WINTER MONTHS. THE OFFICIAL CPC-IRI ENSO OUTLOOK FAVORS 
EL NINO THIS WINTER AND SPRING AT A GREATER THAN 70% PROBABILITY THROUGH JFM 
2019 AND THEN DECREASING TO NEAR 50% BY AMJ 2019.  
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS
THIS SET OF OUTLOOKS UTILIZED TYPICAL IMPACTS ASSOCIATED WITH EL NINO EVENTS, 
ALBEIT WITH THE UNDERSTANDING THAT THIS MOST LIKELY WILL BE A WEAK OR 
BORDERLINE MODERATE EVENT AND NOTING THE CONFIDENCE IN IMPACTS IN INTENSITY AND 
LOCATION IS SOMEWHAT LOW. ADDITIONALLY, THE LACK OF A COHERENT CONVECTIVE 
RESPONSE TO THIS POINT ADDS MORE UNCERTAINTY TO THE EQUATION: EVEN IF SSTS ARE 
SUFFICIENTLY HIGH FOR THIS TO BE CONSIDERED AN EL NINO WINTER, THE 
TROPICAL-EXTRATROPICAL TELECONNECTIONS MAY BE ESPECIALLY WEAK.  OTHER FACTORS 
FROM BOTH THE TROPICS (E.G., MJO) AND HIGH/POLAR LATITUDES (E.G., AO/NAO, NPO, 
ETC.) ARE LIKELY TO FAVOR HIGH VARIABILITY OVER THE WINTER AND EARLY SPRING 
SEASONS AND LIKELY WILL EXPLAIN CONSIDERABLY MORE VARIANCE IN THE UPCOMING 
SEASONAL MEANS IN TEMPERATURE AND PRECIPITATION.
LOCAL COASTAL SSTS AND CONSIDERATIONS OF AREAS OF ANOMALOUS SNOWFALL WERE 
CONSIDERED IN MAKING THE OUTLOOKS DURING THE EARLIER LEADS.
CONTRIBUTIONS TO THE OUTLOOKS ALSO INCLUDED BIAS-CORRECTED AND CALIBRATED 
DYNAMICAL MODEL GUIDANCE FROM THE NMME AND IMME ENSEMBLE SUITES (BOTH ENSEMBLE 
MEAN AND THEIR PARTICIPANT MODELS) THROUGH AMJ 2019. DYNAMICAL MODEL GUIDANCE 
FROM THE UKMET OFFICE, ESPECIALLY WITH RESPECT TO THE FORECAST SIGN OF THE NAO, 
WAS ALSO CONSIDERED. EMPIRICAL AND STATISTICAL FORECAST MODELS ALSO PLAYED A 
LARGE ROLE THROUGHOUT ALL FORECAST LEADS. THESE INCLUDED GUIDANCE FROM A 
COMBINED ENSO-OCN TOOL, THE CCA, THE SST-CA, AND "BRIDGING"  TECHNIQUES. 
MOREOVER, CONSOLIDATION FORECAST GUIDANCE PRODUCTS FROM STATISTICAL ONLY, 
DYNAMICAL MODEL ONLY, AND COMBINED STATISTICAL AND DYNAMICAL FORECAST TOOLS WAS 
HEAVILY UTILIZED. OCN ALSO WAS UTILIZED OFTEN THROUGHOUT THE OUTLOOK LEADS FOR 
BOTH TEMPERATURE AND PRECIPITATION.
PROGNOSTIC DISCUSSION OF OUTLOOKS - DJF 2018 TO DJF 2019
TEMPERATURE
IN REVIEWING THE FIRST FOUR FORECAST LEADS THROUGH THE WINTER 2018-2019 AND 
EARLY SPRING MONTHS IN 2019, THE DJF-FMA 2018-2019 TEMPERATURE OUTLOOKS ARE 
SIMILAR AND DEPICT ELEVATED ODDS OF ABOVE-NORMAL TEMPERATURES FOR ALASKA AND 
MUCH OF THE WESTERN CONUS WITH EC NOTED FOR THE MUCH OF THE EASTERN CONUS. AS 
WE PROGRESS THROUGH THE WINTER INTO THE EARLY SPRING, THE FORECAST SEQUENCE 
DEPICTS A TENDENCY FOR THE ODDS OF ABOVE-NORMAL TEMPERATURES TO DECREASE ALONG 
WITH FORECAST COVERAGE ACROSS THE NORTHERN TIER OF THE CONUS. AT THE SAME TIME, 
THERE IS AN EASTWARD EXPANSION OF ENHANCED ODDS FOR ABOVE-NORMAL TEMPERATURES 
ACROSS THE SOUTHERN TIER. FOR THESE LEADS, OTHER THAN AREAS IN ALASKA AND THE 
PACIFIC NORTHWEST, THE PROBABILITIES ARE QUITE MODEST. 
THIS DEPICTED EVOLUTION (VARIATION OF AREAS DENOTED AS EC) IN THE FORECAST OF 
SEASONAL MEAN TEMPERATURES IS A RESULT OF CHANGING AREAS WITH THE GREATEST 
UNCERTAINTY AND SO LOWER FORECAST CONFIDENCE. UNDERSTANDING THE WEAK NATURE OF 
EL NINO ANTICIPATED THIS WINTER AND CONFRONTED BY CONSIDERABLE CONFLICTING 
FORECAST TOOL INFORMATION IN THESE AREAS, EC IS FORECAST AT THIS TIME. DURING 
DJF, JFM, AND FMA 2018-2019, DYNAMICAL MODEL GUIDANCE FROM THE NMME DEPICTS 
CALIBRATED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES NEARLY UNANIMOUSLY 
ACROSS MUCH OF THE WESTERN CONUS AND NORTH-CENTRAL CONUS IN AGREEMENT WITH THE 
AFOREMENTIONED STATISTICAL FORECAST TOOLS AND OBJECTIVE, SKILL WEIGHTED 
CONSOLIDATION GUIDANCE PRODUCTS. HOWEVER, THE VARIOUS MODELS HAVE COME INTO 
CONSENSUS ON A WEAKNESS EXTENDING FROM THE SOUTH-CENTRAL CONUS NORTHEASTWARD TO 
PARTS OF NEW ENGLAND. IN ADDITION, THE UKMET GLOSEA5 FORECAST SYSTEM PREDICTS A 
NEGATIVE NAO DIPOLE IN THE MEAN SEA LEVEL PRESSURE FIELD, CONSISTENT WITH A 
WEAKNESS OVER THE SOUTHEASTERN THIRD OF THE CONUS. IN FACT, THERE WAS A LOT OF 
INTERNAL DISCUSSION ABOUT THE INTRODUCTION OF PROBABILITIES FAVORING 
BELOW-NORMAL TEMPERATURES SOMEWHERE OVER THE INTERIOR SOUTHEAST. HOWEVER, THERE 
IS JUST NOT ENOUGH OBJECTIVE FORECAST GUIDANCE TO FAVOR SUCH A FORECAST. IN 
THIS CASE A FORECAST OF EQUAL CHANCES IS ACTUALLY QUITE A BIT COOLER THAN THE 
PREPONDERANCE OF OBJECTIVE DATA WOULD WARRANT. OUR FORECAST TEAM ERRED ON THAT 
SIDE GIVEN THE COLDER DECEMBER OUTLOOK THAN SUGGESTED BY THE LOW-FREQUENCY 
FORECAST GUIDANCE, AS WELL AS AN EXPECTATION OF A TENDENCY TOWARD A NEGATIVE 
NAO AND ENHANCED MJO ACTIVITY BIASED TOWARD THE WEST-CENTRAL PACIFIC.
PROGRESSING INTO SPRING AND SUMMER, THE FORECAST TENDS TOWARD THE OBJECTIVE 
MODEL GUIDANCE WITH INCREASING COVERAGE OF ABOVE-NORMAL TEMPERATURES OVER MUCH 
OF THE EASTERN CONUS. THIS IS ALMOST UNANIMOUS AMONG THE VARIOUS FORECAST TOOLS 
AND CONSISTENT WITH LONG-TERM TRENDS.
FOR ALASKA AND THE WESTERN CONUS, THERE IS LITTLE SUPPORT FOR ANY OTHER 
FORECAST BESIDES ELEVATED ODDS FOR ABOVE-NORMAL TEMPERATURES FOR THIS PORTION 
OF THE SET OF OUTLOOKS AS WELL AS THE REMAINING OUTLOOKS THROUGH DJF 2019-2020. 
THE PRIMARY DRIVER FOR THE OUTLOOKS FROM MJJ 2019 THROUGH DJF 2019-2020 WERE 
OCN, ENSO-OCN, AND STATISTICAL OBJECTIVE, SKILL WEIGHTED CONSOLIDATION FORECAST 
TOOLS. BY FALL AND WINTER 2019-2020, THE FORECAST IS DAMPED RELATIVE TO THE 
OBJECTIVE GUIDANCE - WHILE VERY HIGH OBJECTIVE PROBABILITIES COME FROM THE 
AGREEMENT AMONG ALL THE EMPIRICAL FORECAST TOOLS, THE PHYSICAL UNDERPINNINGS OF 
THE FORECAST SIGNAL ARE NOT READILY APPARENT.
PRECIPITATION
THE OUTLOOKS FOR SEASONAL TOTAL PRECIPITATION AMOUNTS UTILIZED INFORMATION 
CONSISTENT WITH AN ANTICIPATED (ALBEIT WEAK) EL NINO EVENT FROM DJF 2018-2019 
THROUGH MAM 2019. DYNAMICAL MODEL GUIDANCE FROM THE NMME AND IMME CONTRIBUTED 
TO THE OUTLOOKS AS WELL THROUGH AMJ 2019. GIVEN THE RANGE OF SOLUTIONS AND 
GENERALLY WEAK INDICATORS FROM MANY OF THE FORECAST TOOLS, PROBABILITIES FOR 
EITHER FORECAST CATEGORY (ABOVE- OR BELOW-NORMAL PRECIPITATION) ARE QUITE 
MODEST. ABOVE-NORMAL PRECIPITATION IS FAVORED OVER THE SOUTHERN TIER OF THE 
CONUS INCLUDING CALIFORNIA DURING DJF, BUT GRADUALLY CONTRACTING TO INCLUDE THE 
SOUTH-CENTRAL AND SOUTHEASTERN CONUS BY MAM 2019. THE SLIGHT TILT TOWARD 
ABOVE-NORMAL PRECIPITATION IN CALIFORNIA FOR DJF WAS BASED ON THE DYNAMICAL 
MODEL CONSENSUS, INCLUDING INTERNATIONAL MODELS, ALONG WITH THE TILT TOWARD 
ABOVE-NORMAL PRECIPITATION DEPICTED IN THE DECEMBER 2018 FORECAST. 
PROBABILITIES FAVORING ABOVE-NORMAL PRECIPITATION GRADUALLY INCREASE IN 
COVERAGE OVER THE CENTRAL CONUS, SHIFTING NORTHWARD WITH TIME.
BELOW-NORMAL PRECIPITATION IS NO LONGER FAVORED OVER THE NORTHERN HIGH PLAINS 
AND NORTHERN ROCKIES DURING THE EARLY LEADS. THERE WAS A REMARKABLE LACK OF 
SUPPORT AMONG THE VARIOUS FORECAST TOOLS FOR THIS SIGNAL. WHILE IT IS AMONG THE 
ROBUST ENSO FOOTPRINTS, LONG TERM TRENDS AND THE CONSENSUS OF FORECAST TOOLS 
LEAD TO EQUAL CHANCES BEING DEPICTED FOR THIS REGION THROUGH AMJ 2019. 
BELOW-NORMAL PRECIPITATION IS FAVORED FOR PARTS OF THE GREAT LAKES AND THE OHIO 
VALLEY FROM DJF 2018-2019 TO FMA 2019. EL NINO CONSIDERATIONS AND CONSISTENT 
DYNAMICAL AND STATISTICAL MODEL GUIDANCE FAVORED ELEVATED ODDS OF ABOVE-NORMAL 
PRECIPITATION FOR SOUTHERN ALASKA THROUGH FMA 2019. 
FROM AMJ 2019 THROUGH NDJ 2019-2020, THE OUTLOOKS ARE BASED PREDOMINATELY ON 
LONG TERM TRENDS AND MODEL GUIDANCE WHEN AVAILABLE. TO THIS END, THE MOST BROAD 
AND CONSISTENT SIGNALS FOR THIS ARE ELEVATED ODDS FOR BELOW-NORMAL 
PRECIPITATION IN THE NORTHERN ROCKIES FROM MJJ 2019 THROUGH JAS 2019 AND A 
LARGER AREA FOR FAVORED ABOVE-NORMAL PRECIPITATION FOR PARTS OF THE PLAINS, 
GREAT LAKES, NORTHEAST, OHIO VALLEY, AND MID-ATLANTIC FROM AMJ 2019 THROUGH SON 
2019. LONG-TERM TRENDS FAVOR ABOVE-NORMAL PRECIPITATION FOR MUCH OF ALASKA 
THROUGHOUT THE LONGER LEADS AS WELL.
FORECASTER: STEPHEN BAXTER
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 DEC 20 2018
1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 
FORECAST RELEASE.
$$