PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830AM EST THURSDAY JAN 15 2015 30-DAY OUTLOOK DISCUSSION FOR FEBRUARY 2015 THE FEBRUARY 2015 OUTLOOK REFLECTS A FAIRLY HIGH AMOUNT OF UNCERTAINTY, GIVEN SIGNIFICANT DIFFERENCES AMONG VARIOUS CLIMATE MODELS, AND THE CONTINUED LACK OF A ROBUST ATMOSPHERIC RESPONSE TO THE NEAR- TO ABOVE-AVERAGE EQUATORIAL PACIFIC SSTS. DURING THE PAST 4 WEEKS, EQUATORIAL SEA-SURFACE TEMPERATURES (SST) WERE ABOVE-AVERAGE ACROSS MOST OF THE PACIFIC, THOUGH THE ANOMALIES HAVE RECENTLY WEAKENED. THE LATEST WEEKLY NINO 3.4 INDEX IS +0.4 C. POSITIVE SUBSURFACE TEMPERATURE ANOMALIES HAVE PERSISTED ACROSS MOST OF THE CENTRAL AND EASTERN EQUATORIAL PACIFIC SINCE MID-NOVEMBER, TO A DEPTH OF 50-100 METERS. WHILE OCEANIC INDICATORS FAVOR AN EL NINO, ATMOSPHERIC INDICATORS CONTINUE TO FAVOR ENSO-NEUTRAL CONDITIONS. DURING THE PAST 30-DAYS, ENHANCED CONVECTION AND PRECIPITATION HAS BEEN OBSERVED OVER INDONESIA, THE PHILIPPINES, NORTHERN AUSTRALIA, AND THE WESTERN PACIFIC. SUPPRESSED CONVECTION AND PRECIPITATION WAS OBSERVED NEAR THE DATE LINE. LOW-LEVEL (850-HPA) WINDS WERE NEAR-AVERAGE ACROSS MOST OF THE EQUATORIAL PACIFIC. THE CONVECTION AND LOW-LEVEL WIND PATTERNS ARE NOT CONSISTENT WITH AN EL NINO. COLLECTIVELY, THE OCEANIC AND ATMOSPHERIC INDICATORS SUPPORT THE CONTINUATION OF ENSO-NEUTRAL CONDITIONS. THIS CONTINUED LACK OF COUPLING BETWEEN THE OCEAN AND ATMOSPHERE SUGGESTS THAT THE WINDOW OF OPPORTUNITY FOR A WEAK WARM EVENT IS RAPIDLY NARROWING. THERE IS AN APPROXIMATELY 50-60 PERCENT CHANCE OF EL NINO CONDITIONS DURING THE NEXT TWO MONTHS, AFTER WHICH ENSO-NEUTRAL IS FAVORED. THE MONTHLY PACIFIC DECADAL OSCILLATION (PDO) INDEX FOR DECEMBER 2014 IS +2.51, WHICH IS THE HIGHEST DECEMBER VALUE OF RECORD (SINCE 1900). REGRESSIONS OF FEBRUARY TEMPERATURE ON DECEMBER PDO VALUES SUPPORT A RELATIVELY COLD PATTERN FOR MUCH OF THE CONUS EAST OF THE ROCKIES. THE MADDEN JULIAN OSCILLATION IS CURRENTLY ACTIVE, WITH THE ENHANCED CONVECTIVE PHASE CENTERED OVER THE WESTERN PACIFIC, AND SUPPRESSED CONVECTIVE PHASES OVER THE INDIAN OCEAN AND IN THE WEST-CENTRAL PACIFIC NEAR THE DATE LINE. DURING THE NEXT TWO WEEKS, THE ENHANCED PHASE OF THE MJO IS PREDICTED TO SHIFT EASTWARD INTO THE WESTERN HEMISPHERE, AND DECREASE IN AMPLITUDE. LAGGED COMPOSITES ON THE MJO FAVOR A COOLING DOWN FOR MUCH OF THE CONUS DURING WEEK 2. IT IS DIFFICULT TO SAY HOW MUCH OF A ROLE THE MJO MAY PLAY IN INFLUENCING U.S. CLIMATE IN FEBRUARY. CFS AND ECMWF DYNAMICAL MODEL GUIDANCE FOR THE WEEK 3 AND WEEK 4 PERIODS DEPICT A MODERATING TREND IN SURFACE TEMPERATURES ACROSS THE CENTRAL AND EASTERN CONUS. THESE MODELS ARE ALSO VERY PERSISTENT IN PREDICTING ABOVE-AVERAGE MEAN TEMPERATURES ACROSS THE WESTERN CONUS AND ALASKA. AN ASSORTMENT OF CLIMATE MODELS FOR FEBRUARY 2015 PREDICT A FAIRLY WIDE RANGE OF POSSIBLE OUTCOMES. THE NATIONAL MULTI-MODEL ENSEMBLE (NMME) AND THE INTERNATIONAL MULTI-MODEL ENSEMBLE (IMME) FORECAST ENHANCED CHANCES OF ABOVE-AVERAGE MEAN TEMPERATURES IN ALASKA, THE WESTERN CONUS, AND TO A MODEST DEGREE, PARTS OF THE SOUTHEAST. THEY ALSO ANTICIPATE ENHANCED CHANCES OF BELOW-AVERAGE MEAN TEMPERATURES IN PARTS OF TEXAS. THE INDIVIDUAL MODEL INPUTS TO THE NMME ALL AGREE ON THE PREDICTED RELATIVE WARMTH IN ALASKA, AND WITH ONE EXCEPTION, THEY ALSO AGREE ON THE WARMTH OVER THE WESTERN CONUS. HOWEVER, FOR REMAINING AREAS OF THE CONUS, TEMPERATURE SIGNALS AMONG THE VARIOUS MODELS ARE EITHER WEAK OR CONFLICTING, SUGGESTING LITTLE PREDICTIVE SIGNAL FOR TEMPERATURE ANOMALIES. THE OFFICIAL FEBRUARY 2015 TEMPERATURE OUTLOOK THEREFORE FAVORS ABOVE-AVERAGE TEMPERATURES IN ALASKA, THE WESTERN CONUS, AND FLORIDA, AND BELOW-AVERAGE TEMPERATURES IN TEXAS. FOR PRECIPITATION, THE NMME, IMME, AND CFS PREDICT ENHANCED ODDS OF ABOVE-MEDIAN PRECIPITATION FROM SOUTHERN CALIFORNIA EASTWARD ACROSS THE SOUTHWEST, SOUTHERN ROCKIES, AND SOUTHERN GREAT PLAINS, WITH THE HIGHER PROBABILITIES IN NEW MEXICO AND TEXAS. THESE SAME MODELS ALSO ANTICIPATE ELEVATED ODDS OF BELOW-MEDIAN PRECIPITATION ACROSS PARTS OF THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. THESE PREDICTED CLIMATE ANOMALIES HAVE REASONABLE SUPPORT FROM A MAJORITY OF THE CLIMATE MODELS WHICH CONSTITUTE THE NMME. SOME MODELS ALSO FORECAST A TILT IN THE ODDS TOWARD DRYNESS NEAR THE GREAT LAKES/OHIO VALLEY REGION, AND WETNESS ALONG THE SOUTH-CENTRAL AND SOUTHEASTERN ALASKA COAST, BUT THEY APPEAR TO BE EITHER TOO WEAK OR DISAGREE SUBSTANTIALLY IN PREDICTED LOCATION TO BE USED RELIABLY. THE OFFICIAL FEBRUARY 2015 PRECIPITATION OUTLOOK THEREFORE FAVORS ABOVE-MEDIAN PRECIPITATION FROM SOUTHERN CALIFORNIA EASTWARD TO TEXAS, AND BELOW-MEDIAN PRECIPITATION IN THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. IN AREAS WHERE CLIMATE SIGNALS ARE WEAK OR CONFLICTING, SUCH THAT THE LIKELIHOODS OF MONTHLY MEAN TEMPERATURES OR MONTHLY ACCUMULATED PRECIPITATION AMOUNTS ARE SIMILAR TO CLIMATOLOGICAL PROBABILITIES, EQUAL CHANCES (EC) IS INDICATED. 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: ANTHONY ARTUSA 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. AN UPDATED MONTHLY OUTLOOK... FOR FEB WILL BE ISSUED ON SAT JANUARY 31 2015 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. $$