PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 
830AM EDT THURSDAY MAY 17 2012 
 
30-DAY OUTLOOK DISCUSSION FOR JUNE 2012 
 
THE LA NINA CONDITIONS THAT WERE OBSERVED EARLIER IN THE YEAR HAVE NOW 
DISSIPATED, LEADING TO AN OCEANIC AND ATMOSPHERIC STATE CONSISTENT WITH NEUTRAL 
ENSO CONDITIONS.  EQUATORIAL PACIFIC SEA SURFACE TEMPERATURE (SST) ANOMALIES 
HAVE CONSISTENTLY RISEN IN THE PAST FEW MONTHS AND ARE NOW WITHIN A FEW TENTHS 
OF A DEGREE C OF NORMAL, EXCEPT NEAR THE SOUTH AMERICAN COAST WHERE POSITIVE 
ANOMALIES OF BETWEEN 1 AND 2 DEGREES C HAVE DEVELOPED.  THE ATMOSPHERIC 
CONDITIONS OVER THE TROPICAL PACIFIC OCEAN HAVE ALSO TRANSITIONED FROM TYPICAL 
LA NINA PATTERNS EARLIER IN THE YEAR TO BECOME WEAK AND DISORGANIZED, 
REFLECTING ENSO NEUTRAL CONDITIONS.  THE HEAT CONTENT IN THE UPPER 300 METERS 
OF THE EASTERN AND CENTRAL EQUATORIAL PACIFIC IS NOW ABOVE NORMAL, SUGGESTING 
THAT SST ANOMALIES WILL LIKELY CONTINUE TO INCREASE IN THE COMING WEEKS, AND 
AVERAGE SLIGHTLY POSITIVE IN JUNE.  MOST DYNAMIC AND STATISTICAL SST FORECASTS 
FOR THE EAST-CENTRAL EQUATORIAL PACIFIC INDICATE THAT SST ANOMALIES SHOULD 
BECOME SLIGHTLY POSITIVE DURING THE MONTH OF JUNE, FAVORING CONTINUED NEUTRAL 
ENSO CONDITIONS. 
 
THE TEMPERATURE OUTLOOK FOR JUNE INDICATES ENHANCED PROBABILITIES OF ABOVE 
NORMAL TEMPERATURES ACROSS MUCH OF THE SOUTHERN CONUS.  THIS AREA EXTENDS FROM 
INTERIOR SOUTHERN CALIFORNIA ACROSS THE SOUTHERN ROCKIES INTO THE SOUTHERN 
GREAT PLAINS, THE GULF COAST, AND UP THE ATLANTIC SEABOARD TO THE MID-ATLANTIC 
STATES.  A WIDE VARIETY OF TOOLS SUPPORT THIS PREDICTION, WITH DYNAMIC CLIMATE 
MODELS AND STATISTICAL TOOLS IN GOOD AGREEMENT ON THE EXPECTED ANOMALIES.  DRY 
INITIAL SOIL MOISTURE CONDITIONS ARE OBSERVED IN MOST OF THIS AREA AND IS A 
FACTOR IN THE STRONG CONSENSUS FAVORING POSITIVE ANOMALIES.  BELOW NORMAL SSTS 
ARE OBSERVED OFF THE WEST COAST OF NORTH AMERICA FROM ALASKA TO CENTRAL 
CALIFORNIA, ELEVATING THE CHANCES FOR BELOW NORMAL MEAN TEMPERATURES FROM 
SOUTHWESTERN ALASKA, THE SOUTHERN ALASKAN COAST AND ALONG THE PANHANDLE. BELOW 
NORMAL TEMPERATURES ARE ALSO FAVORED ALONG THE WEST COAST FROM WASHINGTON TO 
CENTRAL CALIFORNIA.  THE MAJORITY OF CLIMATE MODELS RUN AS PART OF THE NATIONAL 
MULTI-MODEL ENSEMBLE (NMME) SUPPORT THIS FORECAST, HINTING THAT EXPECTED LARGE 
SCALE CIRCULATION PATTERNS MAY ALSO FAVOR NEAR TO BELOW NORMAL MEAN 
TEMPERATURES IN JUNE FROM ALASKA TO THE PACIFIC NORTHWEST.  ELSEWHERE THERE ARE 
CONFLICTING SIGNALS AMONG TOOLS, WITH NO CLEAR REASON TO EXPECT A SHIFT THE 
ODDS FOR BELOW, NEAR, OR ABOVE NORMAL TEMPERATURES FROM THEIR LONG TERM 
CLIMATOLOGICAL VALUES. 
 
THE JUNE PRECIPITATION OUTLOOK CALLS FOR ENHANCED PROBABILITIES OF BELOW MEDIAN 
PRECIPITATION FOR THE PACIFIC NORTHWEST EXTENDING INTO PARTS OF THE GREAT 
BASIN.  MOST OF THE NMME MEMBERS FAVOR DRY CONDITIONS IN THE PACIFIC NORTHWEST, 
WITH A MAJORITY OF MODELS EXTENDING THE AREA OF BELOW MEDIAN PRECIPITATION INTO 
THE SOUTHERN GREAT PLAINS.  THE CFS VERSION 2 MODEL, HOWEVER, INDICATES 
ENHANCED ODDS FOR ABOVE MEDIAN PRECIPITATION IN PARTS OF THE SOUTHERN ROCKIES 
AND SOUTHERN PLAINS, AND HISTORICAL SKILL IN PRECIPITATION PREDICTION IS LOW IN 
THE WARM SEASON, SO THE AREA FAVORING DRY CONDITIONS IS LIMITED TO WEST OF THE 
ROCKIES.  SEVERAL OF THE NMME MODELS FAVOR ABOVE MEDIAN PRECIPITATION IN THE 
SOUTHEAST CONUS, HOWEVER VERY DRY SOIL MOISTURE CONDITIONS MAY OFFSET THIS 
SIGNAL.  THE SOIL MOISTURE CONDITION IS RELIABLY CHOSEN AS A PREDICTOR IN 
REGRESSION RELATIONSHIPS FROM THE SMLR TOOL AND FAVOR DRY CONDITIONS.  SKILL IN 
THESE PREDICTIONS IS VERY LOW, SO EQUAL CHANCES FOR THE THREE PRECIPITATION 
CATEGORIES FOR THE SOUTHEAST IS INDICATED.  THE MAJORITY OF NMME MEMBERS FAVOR 
BELOW MEDIAN PRECIPITATION AMOUNTS FOR SOUTHWESTERN ALASKA. 
 
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: DAVID UNGER 
 
 
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 JUN WILL BE ISSUED ON THU MAY 31 2012 
 
 
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. 
 
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