PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830AM EDT THURSDAY JUL 16 2015 30-DAY OUTLOOK DISCUSSION FOR AUGUST 2015 SEA SURFACE TEMPERATURES (SSTS) ARE CURRENTLY MORE THAN ONE DEGREE C ABOVE NORMAL ALONG THE EQUATOR IN THE PACIFIC OCEAN FROM THE SOUTH AMERICAN COAST WESTWARD TO JUST WEST OF THE INTERNATIONAL DATE LINE. SST ANOMALIES ARE GREATER THAN +2.0 DEGREES C IN THE EAST PACIFIC FROM ABOUT 130 W LONGITUDE TO THE SOUTH AMERICAN COAST. ABOVE NORMAL SSTS EXTEND NORTHWARD FROM THE EQUATOR TO COVER AN EXTENSIVE AREA OF THE NORTH PACIFIC TO THE WEST OF NORTH AMERICA. SUBSURFACE OCEAN WATER TEMPERATURES TO A DEPTH OF ABOUT 100 METERS ARE CONSIDERABLY ABOVE NORMAL THROUGHOUT THE EASTERN EQUATORIAL PACIFIC OCEAN. RECENT ATMOSPHERIC OBSERVATIONS OVER THE EASTERN AND CENTRAL TROPICAL PACIFIC OCEAN SUGGEST STRONG OCEAN-ATMOSPHERE COUPLING, WITH UNUSUALLY ACTIVE CONVECTION ACROSS THE CENTRAL AND EAST-CENTRAL EQUATORIAL PACIFIC TOGETHER WITH LARGE SCALE WESTERLY WIND ANOMALIES AT LOW LEVELS OVER THE WEST AND CENTRAL PACIFIC. ATMOSPHERIC AND OCEANIC CONDITIONS SUGGEST CONTINUED STRENGTHENING OF EL NINO CONDITIONS. STATISTICAL AND DYNAMICAL SST FORECASTS INDICATE EL NINO CONDITIONS WILL PERSIST THROUGH WINTER, AND ANOMALIES IN SST ARE LIKELY TO GROW INTO THE BEGINNING OF WINTER AS THE CLIMATOLOGY OF SST COOLS. EL NINO IS LIKELY CONTRIBUTING TO RECENT CLIMATE ANOMALIES OVER NORTH AMERICA AND IS EXPECTED TO HAVE AN INFLUENCE ON CLIMATE ANOMALIES IN AUGUST. CLIMATE MODEL FORECASTS FROM THE LAST FEW MONTHS HAVE SHOWN CONSISTENT NORTH AMERICAN SURFACE TEMPERATURE AND PRECIPITATION ANOMALY PATTERNS. MODEL PREDICTIONS AGREE REASONABLY WELL WITH THE TEMPERATURE AND PRECIPITATION ANOMALIES ASSOCIATED WITH PAST EL NINO EVENTS, ALTHOUGH THE AVERAGE OF CLIMATE MODELS CONTRIBUTING TO THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) IS SUBSTANTIALLY WARMER ACROSS THE NORTHERN U.S. FROM THE NORTHERN ROCKIES INTO THE NORTHEAST. THE CLIMATE FORECAST SYSTEM (CFS) FORECAST FOR AUGUST APPEARS IN CLOSER AGREEMENT WITH ANOMALIES ASSOCIATED WITH EL NINO IMPACTS. THE CLIMATE OUTLOOK FOR AUGUST 2015 IS BASED PRIMARILY ON FORECASTS FROM CLIMATE MODELS OF THE NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME) AND REGRESSIONS OF NORTH AMERICAN SURFACE TEMPERATURE AND PRECIPITATION TO THE NINO 3.4 INDEX. THE FORECAST PREDICTS ELEVATED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES FOR THE U.S. WEST AND ALASKA. BELOW NORMAL TEMPERATURES ARE MORE LIKELY IN AREAS THAT HAVE OBSERVED RECENT ABOVE AVERAGE RAINFALL SUCH AS THE SOUTHERN ROCKY MOUNTAINS AND CENTRAL PLAINS. THIS SIGNAL IS LIKELY IN PART ASSOCIATED WITH ABOVE AVERAGE SOIL MOISTURE AND INCREASED CHANCES OF CONTINUING ANOMALOUSLY WET SOILS IN THE NEXT MONTH. THERE IS CONSENSUS AMONG CLIMATE ENSEMBLE MODELS FOR ABOVE NORMAL TEMPERATURES ALONG THE GULF COAST, THE SOUTH ATLANTIC COAST AND NORTHERN NEW ENGLAND. THERE CONTINUES TO BE CONSENSUS AMONG CLIMATE ENSEMBLE MODELS FOR ABOVE-MEDIAN PRECIPITATION AMOUNTS OVER A LARGE AREA OF THE SOUTHWEST EXTENDING INTO THE CENTRAL PLAINS. ENHANCED TROPICAL STORM ACTIVITY IN THE EASTERN PACIFIC IS LIKELY TO CONTINUE TO PROVIDE ANOMALOUS ATMOSPHERIC MOISTURE TO THE U.S. SOUTHWEST. CLIMATE MODELS PREDICT ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION AS A NORTHWARD EXTENSION OF A LARGE AREA OF ABOVE MEDIAN RAINFALL OVER THE TROPICAL EASTERN PACIFIC OCEAN. REGRESSIONS OF PRECIPITATION AGAINST THE NINO 3.4 INDEX INDICATE ABOVE-MEDIAN PRECIPITATION OVER A LARGE AREA OF THE CENTRAL CONUS AND BELOW-MEDIAN PRECIPITATION OVER A LARGE AREA OF THE CARIBBEAN EXTENDING INTO PARTS OF THE SOUTHERN FLORIDA PENINSULA AND THE GULF COAST OF TEXAS AND LOUISIANA. THIS PATTERN OF PRECIPITATION ANOMALIES IS CONSISTENT IN THE CONSENSUS OF CLIMATE MODELS FROM THE NMME. THERE IS ALSO CONSENSUS AMONG THE NMME MODELS FOR BELOW MEDIAN PRECIPITATION OVER PARTS OF THE PACIFIC NORTHWEST. IN AREAS WHERE THERE ARE NO STATISTICALLY SIGNIFICANT CLIMATE SIGNALS, SUCH THAT THE LIKELIHOODS OF MONTHLY MEAN TEMPERATURES OR MONTHLY ACCUMULATED PRECIPITATION AMOUNTS ARE EQUAL 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: DAN COLLINS 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 AUG WILL BE ISSUED ON FRI JULY 31 2015 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. $$