PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 300 PM EST THU DEC 31 2015 30-DAY OUTLOOK DISCUSSION FOR JANUARY 2016 THE ONGOING, STRONG EL NINO REMAINS AN IMPORTANT DRIVER OF CLIMATE FORECASTS OVER NORTH AMERICA. PLEASE SEE THE ENSO DIAGNOSTIC DISCUSSION AT: HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/ANALYSIS_MONITORING/ENSO_ADVISORY/ FOR A MORE DETAILED ANALYSIS OF EL NINO CONDITIONS ACROSS THE EQUATORIAL PACIFIC. THE LATEST WEEKLY ANALYSIS SHOWS A SLIGHT DECREASE IN SEA-SURFACE TEMPERATURE ANOMALIES. THE MADDEN-JULIAN OSCILLATION (MJO) STRENGTHENED MID MONTH AND CONTINUES TO INFLUENCE THE PATTERN OF TROPICAL CONVECTION. PROJECTIONS BASED ON LAGGED COMPOSITES OF MJO DURING DEC-JAN-FEB IMPLY A TRANSITION TO A COLDER PATTERN FOR THE CONUS. TOOLS SPECIFICALLY TARGETING WEEK3/4 CONDITIONS, BASED ON MJO AND ENSO PHASES, INDICATE A PROLONGED COLD PERIOD. SHORTER TERM (THROUGH 14 DAYS) OUTLOOKS INDICATE A TRANSITION TO A COLDER PATTERN FOR THE CONUS. GIVEN THE SHORTER TERM OUTLOOKS AND THE INFLUENCE OF THE MJO, THE ODDS FOR ABOVE NORMAL TEMPERATURES FOR MUCH OF THE NORTHERN CONUS HAVE BEEN REDUCED AND COVERAGE DECREASED, WHILE ODDS FOR BELOW NORMAL TEMPERATURES OVER THE SOUTHERN CONUS HAVE INCREASED IN COVERAGE. SHORTER-TERM OUTLOOKS (THROUGH 7 DAYS) INDICATE AN ACTIVE SOUTHERN STREAM, WHICH IS CONSISTENT WITH ONGOING EL NINO CONDITIONS AND WEEK3/4 OUTLOOKS BASED ON MJO AND ENSO PHASES. SO ODDS FOR ABOVE MEDIAN PRECIPITATION HAVE BEEN INCREASED ACROSS CALIFORNIA, TEXAS, AND FLORIDA. ALSO, A SLIGHT EASTWARD SHIFT IN THE AREA FAVORED TO RECEIVED BELOW MEDIAN PRECIPITATION WAS INTRODUCED, BASED ON THE LATEST MODEL GUIDANCE. ----------- PREVIOUS MESSAGE (FROM DECEMBER 15) IS SHOWN BELOW ------------ THE ONGOING, STRONG EL NINO REMAINS AN IMPORTANT DRIVER OF CLIMATE FORECASTS OVER NORTH AMERICA. PLEASE SEE THE ENSO DIAGNOSTIC DISCUSSION AT: HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/ANALYSIS_MONITORING/ENSO_ADVISORY/ FOR A MORE DETAILED ANALYSIS OF SEA SURFACE TEMPERATURES ACROSS THE EQUATORIAL PACIFIC. THE CURRENT EVENT IS AMONG THE STRONGEST ON RECORD AND IS FORECAST TO PERSIST INTO SPRING 2016. THEREFORE, REGRESSIONS OF THE NOVEMBER NINO 3.4 INDEX ONTO JANUARY SURFACE TEMPERATURE AND PRECIPITATION ARE CONSIDERED IN THE OUTLOOK. THOSE REGRESSIONS INDICATE A SHIFT TOWARD ABOVE NORMAL TEMPERATURES OVER ALASKA, THE PACIFIC NORTHWEST, AND NEAR THE UPPER GREAT LAKES, WITH BELOW NORMAL TEMPERATURES FROM THE SOUTHERN PLAINS TO THE SOUTHEAST COAST. WHEN THOSE REGRESSIONS ARE APPLIED TO PRECIPITATION, THE STRONGEST SIGNALS ARE FOR ABOVE MEDIAN PRECIPITATION ALONG MUCH OF THE WEST COAST AND ACROSS THE SOUTHEAST, WITH LITTLE SIGNAL ELSEWHERE ACROSS NORTH AMERICA. THE MADDEN-JULIAN OSCILLATION IS ALSO A POTENTIAL CONTRIBUTOR TO THE VARIABILITY OVER NORTH AMERICA DURING JANUARY. CURRENTLY, THE REAL-TIME MULTIVARIATE MJO INDEX (RMM) INDICATES ENHANCED CONVECTION OVER THE MARITIME CONTINENT. SOME MODELS INDICATE AN EASTWARD PROPAGATION OF A RELATIVELY STRONG SIGNAL TO THE WESTERN PACIFIC, WHICH WOULD DESTRUCTIVELY INTERFERE WITH THE ONGOING EL NINO AND POTENTIALLY DISRUPT THE DOWNSTREAM RESPONSE OVER NORTH AMERICA. THE UNCERTAINTY RELATED TO THE MJO LEADS TO SOMEWHAT REDUCED COVERAGE AND LOWER PROBABILITIES THAN IF THE FORECAST ONLY CONSIDERED EL NINO AND DYNAMICAL MODEL OUTPUTS. DYNAMICAL MODEL OUTPUTS, INCLUDING THE NMME AND CFS, PLAYED A ROLE IN THE OUTLOOKS AS WELL. IN THE TEMPERATURE FIELDS, MOST OF THE MODELS IN THE NMME SUITE INDICATE PATTERNS CONSISTENT WITH THE EL NINO REGRESSIONS, WITH SOME SMALL SPATIAL SHIFTS. THE CFS IS THE WARMEST OF THE MODELS, WITH LITTLE TO NO AREA OF BELOW NORMAL TEMPERATURES OVER THE CONUS, BUT A COLDER SIGNAL OVER WESTERN ALASKA. MORE RECENT RUNS OF THE CFS INDICATE A WARMER PATTERN FROM THE NORTHERN AND CENTRAL GREAT PLAINS TO THE EAST COAST, INCREASING ODDS FOR BELOW NORMAL TEMPERATURES OVER THE INTERIOR WESTERN CONUS AND A WEAKENING COLD SIGNAL OVER WESTERN ALASKA. THE LATEST WEEK 3 AND 4 (THROUGH JAN 13) OUTPUT FROM THE CFS INDICATES A MUCH STRONGER COLD SIGNAL OVER ALASKA AND THE WESTERN CONUS, INDICATING THAT THE FORECAST FOR THE LATTER HALF OF JANUARY IS WARMER FOR MUCH OF THE WEST AND ALASKA. THIS MAY BE REFLECTIVE OF A POTENTIAL PATTERN CHANGE ASSOCIATED WITH MJO ACTIVITY. THE NMME MODEL OUTLOOKS FOR PRECIPITATION ARE ALSO CONSISTENT WITH CANONICAL, SEASONAL EL NINO COMPOSITES AND CORRELATION MAPS. GUIDANCE FROM THE CFS HAS BEEN CONSISTENT AND ALIGNS WELL WITH CORRELATION MAPS OF JANUARY PRECIPITATION WITH NOVEMBER NINO3.4 VALUES. THOSE CORRELATIONS IMPLY ABOVE MEDIAN PRECIPITATION ACROSS THE SOUTHERN TIER OF THE CONUS, ALONG MUCH OF THE WEST COAST, AND SOUTHERN PORTIONS OF THE MID-ATLANTIC. WEEK 3 AND 4 OUTLOOKS INDICATE DRIER CONDITIONS OVER NORTHERN CALIFORNIA AND WETTER CONDITIONS OVER WESTERN ALASKA, COMPARED TO MONTHLY RUNS OF THE CFS, INDICATING HIGH UNCERTAINTY FOR THE JANUARY OUTLOOK AS A WHOLE IN THESE AREAS. THE MAIN FACTORS THAT USUALLY INFLUENCE THE MONTHLY CLIMATE OUTLOOK INCLUDE: 1) EL NINO AND LA NINA - WHICH COMPRISE ENSO. IMPACTS OF THESE EVENTS ARE SUMMARIZED BY SEPARATING 3-MONTH OBSERVATIONS FROM THREE OR MORE DECADES INTO EL NINO, NEUTRAL AND LA NINA SETS, AVERAGING EACH SEPARATELY, AND THEN COMPUTING ANOMALIES. THESE ARE CALLED "COMPOSITES" AND USED AT TIMES TO SUBJECTIVELY MODIFY THE FORECAST. 2) TRENDS - APPROXIMATED BY THE OCN TOOL AS THE DIFFERENCE BETWEEN THE MOST RECENT 10-YEAR MEAN OF TEMPERATURE OR 15-YEAR MEAN OF PRECIPITATION FOR A GIVEN LOCATION AND TIME OF YEAR AND THE 30-YEAR CLIMATOLOGY PERIOD (CURRENTLY 1981-2010). 3) THE TROPICAL 30-60 DAY OSCILLATION - CALLED THE MADDEN JULIAN OSCILLATION (MJO) - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS. 4) THE ARCTIC OSCILLATION (AO), THE SIMILAR NORTH ATLANTIC OSCILLATION (NAO), AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS - WHICH AFFECT THE TEMPERATURE ANOMALY PATTERN ESPECIALLY DURING BOREAL WINTER AND ARE GENERALLY CONSIDERED TO HAVE LOW PREDICTABILITY. 5) THE PACIFIC DECADAL OSCILLATION (PDO) - AN ENSO-LIKE PATTERN OF CLIMATE VARIABILITY AFFECTING THE TROPICS AND THE NORTH PACIFIC AND NORTH AMERICAN REGIONS, BUT WHICH VARIES ON A MUCH LONGER TIME-SCALE THAN ENSO. 6) PERSISTENTLY DRY OR WET SOILS IN THE SPRING AND SUMMER AND SNOW AND ICE COVER ANOMALIES IN THE WINTER. THESE FACTORS TEND TO PERSIST FOR LONG PERIODS AND ACT AS A KIND OF MEMORY IN THE CLIMATE SYSTEM. 7) STATISTICAL FORECAST MODELS - CANONICAL CORRELATION ANALYSIS (CCA), SCREENING MULTIPLE LINEAR REGRESSION (SMLR), CONSTRUCTED ANALOG (CA), AND ENSEMBLE CCA (ECCA). 8) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM VERSION 2 (CFS) AND FOR THE ZERO-LEAD UPDATE FORECASTS THE NCEP GLOBAL ENSEMBLE FORECAST SYSTEM (GEFS). AN EXPERIMENTAL FORECAST SYSTEM, THE NATIONAL MULTI-MODEL ENSEMBLE (NMME), COMPRISED OF SEVERAL DYNAMICAL MODELS IS ALSO USED. FORECASTER: MATTHEW ROSENCRANS THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1981 AND 2010, FOLLOWING THE WORLD METEOROLOGICAL ORGANIZATION CONVENTION OF USING THE MOST RECENT 3 COMPLETE DECADES AS THE CLIMATE 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. THE NEXT MONTHLY OUTLOOK...FOR FEB ... WILL BE ISSUED ON THU JAN 21 2016 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. $$