PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 830AM EDT THURSDAY JUL 19 2012 30-DAY OUTLOOK DISCUSSION FOR AUGUST 2012 ENSO NEUTRAL CONDITIONS CONTINUED INTO JULY. HOWEVER, POSITIVE EQUATORIAL PACIFIC SEA SURFACE TEMPERATURE (SST) ANOMALIES HAVE GROWN, EXCEEDING +0.5 C ACROSS THE EASTERN PACIFIC OCEAN BY THE END OF JUNE. SST ANOMALIES ARE SMALL ACROSS MUCH OF THE WESTERN AND CENTRAL PACIFIC WHERE DEPARTURES FROM NORMAL ARE WITHIN 0.5 C. AT DEPTH, OCEAN TEMPERATURES ARE GENERALLY ABOVE AVERAGE WITH THE LARGEST POSITIVE ANOMALIES (3 TO 4 CELSIUS DEGREES) CENTERED FROM 160E-160W AT 150 METER DEPTH AND FROM 130W-110W AT 50 METER DEPTH. THE LATEST DYNAMICAL AND STATISTICAL SST FORECASTS FOR THE NINO 3.4 REGION INDICATE CONTINUED SLIGHTLY POSITIVE DEPARTURES FROM NORMAL DURING THE MONTH OF AUGUST, WITH BORDERLINE ENSO NEUTRAL/WEAK EL NINO CONDITIONS EXPECTED. THE AUGUST 2012 TEMPERATURE OUTLOOK DEPICTS ENHANCED ODDS FOR ABOVE-NORMAL MEAN TEMPERATURES STRETCHING FROM THE INTERIOR WEST AND MOST OF THE ROCKIES EASTWARD TO INCLUDE MOST OF THE CENTRAL AND EASTERN CONUS. THE PRIMARY DRIVERS FOR THIS FORECAST ARE CONSISTENT SIGNATURES FROM CLIMATE MODEL FORECASTS (CFSV1, CFSV2 AND NMME) AND LOW SOIL MOISTURE CONDITIONS ACROSS THE EAST-CENTRAL CONUS. LONG TERM TRENDS ARE STRONG THIS TIME OF YEAR ACROSS THE SOUTHWEST AND SOUTHERN ROCKIES AND ARE INCLUDED IN THE MIX OF INPUT TOOLS. THE LARGEST PROBABILITIES ARE INDICATED OVER THE EAST-CENTRAL CONUS, WHICH HAS VERY LOW SOIL MOISTURE VALUES AND CORRESPONDINGLY SEVERE REDUCTIONS IN EVAPOTRANSPIRATION, BOTH OF WHICH CAN RESULT IN PERPETUATING THE REGIONAL DROUGHT. IN NORTHERN ALASKA, ODDS FAVOR ABOVE-NORMAL TEMPERATURES DUE PRIMARILY TO THE CFSV2 AND ABNORMALLY WARM SSTS. BELOW-NORMAL AUGUST MEAN TEMPERATURES ARE FAVORED FOR THE COASTAL REGIONS OF BOTH THE PACIFIC NORTHWEST AND SOUTHERN ALASKA, SUPPORTED BY THE CFSV1 AND (TO A LESSER EXTENT) THE CFSV2 AND NMME MODELS, AS WELL AS ABNORMALLY COOL SSTS. ELSEWHERE THERE ARE CONFLICTING SIGNALS AMONG TOOLS, AND SO EQUAL CHANCES FOR BELOW-, NEAR-, OR ABOVE-NORMAL AUGUST MEAN TEMPERATURES ARE INDICATED. THE AUGUST 2012 PRECIPITATION OUTLOOK FAVORS ABOVE-MEDIAN PRECIPITATION FOR MUCH OF THE SOUTHWEST U.S. IN RELATION TO AN ACTIVE MONSOON, AND NORTHWESTERN PORTIONS OF ALASKA. THIS IS IN GENERALLY GOOD AGREEMENT WITH CLIMATE MODELS SUCH AS THE CFSV1, CFSV2, AND NMME. ODDS FOR BELOW-MEDIAN PRECIPITATION ARE ELEVATED OVER THE MIDWEST, PORTIONS OF THE PACIFIC NORTHWEST, AND MUCH OF THE ALASKA PANHANDLE. CURRENT TEMPERATURE AND SOIL MOISTURE OBSERVATIONS ALONG WITH CLIMATE MODEL PREDICTIONS FAVOR A CONTINUATION OF RELATIVELY WARM AND DRY CONDITIONS ACROSS THE MIDWEST. THE TWO OTHER AREAS OF ANTICIPATED BELOW-MEDIAN RAINFALL (THE PACIFIC NORTHWEST AND THE PANHANDLE OF ALASKA) ARE ATTRIBUTED TO DYNAMICAL MODELS. ELSEWHERE, WHERE THERE ARE EITHER WEAK OR CONFLICTING SIGNALS AMONG THE TOOLS, EQUAL CHANCES (EC) OF BELOW-, NEAR-, AND ABOVE-MEDIAN PRECIPITATION IS PROJECTED. THE MAIN FACTORS WHICH 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) PERSISTANTLY 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 (CFS) AND FOR ZERO-LEAD UPDATE FORECASTS THE NCEP GLOBAL ENSEMBLE FORECAST SYSTEM (GEFS). THE UPGRADED VERSION OF THE CFS (CFSV2) BECAME OPERATIONAL IN LATE MARCH OF 2011. BOTH VERSIONS OF CFS ARE CURRENTLY RUN IN PARALLEL. 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 AUG WILL BE ISSUED ON TUE JULY 31 2012 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. $$