PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 
300PM EST SATURDAY FEB 28 2015 
 
30-DAY OUTLOOK DISCUSSION FOR MARCH 2015 
 
EQUATORIAL SEA-SURFACE TEMPERATURE (SST) ANOMALIES REMAIN ABOVE-NORMAL ACROSS 
MUCH OF THE WESTERN AND CENTRAL EQUATORIAL PACIFIC, WHILE THE SST ANOMALIES 
OVER THE EASTERN PACIFIC ARE NEAR ZERO. THE LATEST WEEKLY NINO 3.4 INDEX IS 
+0.5 C, WHILE THE NINO 4 INDEX IS +1.0 C, AND THE NINO 1+2 INDEX IS -0.1 C. 
 
POSITIVE SUBSURFACE TEMPERATURE ANOMALIES EXPANDED FURTHER ACROSS THE CENTRAL 
AND EAST-CENTRAL EQUATORIAL PACIFIC WITH THE EASTWARD PROGRESSION OF THE 
DOWNWELLING PHASE OF A KELVIN WAVE. ATMOSPHERIC CONDITIONS HAVE NOT SHOWN 
CONSISTENT COUPLING OF POSITIVE SST ANOMALIES TO THE ATMOSPHERE, WITH NEGATIVE 
OUTGOING LONGWAVE RADIATION (OLR) ANOMALIES AND ASSOCIATED ENHANCED CONVECTIVE 
ACTIVITY NEAR THE DATE LINE NOW WEAKENING. 
 
THE UPDATE TO THE MARCH 2015 U.S. CLIMATE OUTLOOK IS BASED ON DYNAMICAL MODEL 
FORECASTS INCLUDING WEATHER PREDICTION MODELS FOR THE FIRST WEEK OF THE MONTH, 
THE NCEP GLOBAL ENSEMBLE FORECAST SYSTEM (GEFS) CALIBRATED USING RETROSPECTIVE 
FORECASTS FOR 1985-2010 AND THE NORTH AMERICAN ENSEMBLE FORECAST SYSTEM (NAEFS, 
A MULTI-MODEL ENSEMBLE THAT COMBINES BIAS-CORRECTED OUTPUT FROM THE NCEP GEFS 
AND THE ENVIRONMENT CANADA ENSEMBLE PREDICTION SYSTEM), FOR 6-10 DAYS AND TWO 
WEEKS LEAD-TIME. GUIDANCE FOR THREE AND FOUR WEEKS LEAD-TIME WAS CONSIDERED 
FROM THE NCEP CLIMATE FORECAST SYSTEM (CFS) AND EUROPEAN CENTER (ECMWF) 
EXTENDED MODELS, AND THE LATEST GUIDANCE FOR THE FULL MONTH OF MARCH FROM THE 
CFS WAS ALSO CONSIDERED. 
 
THE UPDATE TO THE MARCH TEMPERATURE OUTLOOK INDICATES AN INCREASED PROBABILITY 
OF BELOW-NORMAL MEAN TEMPERATURES OVER A MORE EXTENSIVE AREA OF THE EASTERN 
U.S. COVERING MOST REGIONS EAST OF THE ROCKY MOUNTAINS WITH THE EXCEPTION OF 
THE SOUTHEAST. FORECAST GUIDANCE FOR THE FIRST WEEK OF MARCH SUPPORTS THE 
PREDICTION OF BELOW-NORMAL TEMPERATURES FOR THE GREAT PLAINS IN PARTICULAR, 
WHILE MODEL GUIDANCE FOR TWO, THREE AND FOUR WEEKS LEAD-TIME GENERALLY SUPPORTS 
BELOW NORMAL TEMPERATURES FOR THE NORTHEAST. THE PROBABILITY OF ABOVE-NORMAL 
TEMPERATURES WEST OF THE ROCKY MOUNTAINS CONTINUES TO BE INDICATED BY MODEL 
GUIDANCE FROM THE CFS FOR MARCH WITH SOME INCREASE IN UNCERTAINTY. THE FIRST 
WEEK OF MARCH IS LIKELY TO HAVE BELOW-NORMAL TEMPERATURES OVER A LARGE AREA OF 
THE U.S. FROM THE NORTHWEST THROUGH THE GREAT PLAINS INTO THE EAST, WITH A 
GREATER PROBABILITY OF ABOVE-NORMAL TEMPERATURES INDICATED BY GEFS 
REFORECAST-BASED AND NAEFS GUIDANCE FOR THE SECOND WEEK OF THE MONTH. 
 
THE UPDATE TO THE MARCH PRECIPITATION OUTLOOK CONTINUES TO INDICATE AN 
INCREASED PROBABILITY OF ABOVE-MEDIAN OVER MUCH OF THE SOUTHWEST INTO THE 
CENTRAL ROCKIES AND ACROSS A SUBSTANTIAL AREA OF THE SOUTHEAST, WHILE 
BELOW-MEDIAN CONTINUES TO BE MORE LIKELY FOR COASTAL REGIONS OF THE PACIFIC 
NORTHWEST AND NORTHERN CALIFORNIA. CFS FORECASTS CONTINUE TO SUPPORT THIS 
PATTERN OF ANOMALOUS PRECIPITATION FOR THE FULL MONTH WHILE MODEL GUIDANCE 
INDICATES SIGNIFICANT SUBSEASONAL VARIABILITY. OVERALL, AREAS WHERE FORECASTS 
ARE MORE CONSISTENT THROUGHOUT THE MONTH SUCH AS THE SOUTHWEST AND SOUTHEAST 
ARE INDICATED, WHERE AREAS WITH VARIABLE OR WEAK SIGNALS ARE SHOWN AS EQUAL 
CHANCES (EC). 
 
BELOW IS THE MONTHLY DISCUSSION FROM THE HALF-MONTH LEAD, MARCH FORECAST, 
RELEASED FEBRUARY 19TH. 
_____ 
 
THE MARCH 2015 MONTHLY OUTLOOK INCORPORATES MONTHLY FORECAST GUIDANCE FROM 
COUPLED OCEAN-ATMOSPHERE MODELS OF THE NORTH AMERICAN MULTI-MODEL ENSEMBLE 
(NMME), INCLUDING FORECASTS FROM THE NCEP CLIMATE FORECAST SYSTEM (CFS), AND 
FROM THE INTERNATIONAL MULTI-MODEL ENSEMBLE OR IMME, INCLUDING THE EUROPEAN 
CENTER (ECMWF) AND METEO-FRANCE SEASONAL FORECAST SYSTEMS IN ADDITION TO THE 
CFS. AS CURRENT WEATHER FORECAST MODELS EXTEND OUT TO 15 DAYS AND INTO THE 
BEGINNING OF MARCH, GUIDANCE WAS ALSO CONSIDERED FROM THE NCEP GLOBAL ENSEMBLE 
FORECAST SYSTEM (GEFS) CALIBRATED USING RETROSPECTIVE FORECASTS FOR 1985-2010 
AS GENERATED BY THE NOAA EARTH SYSTEM RESEARCH LABORATORY (ESRL), AND THE NORTH 
AMERICAN ENSEMBLE FORECAST SYSTEM (NAEFS, A MULTI-MODEL ENSEMBLE THAT COMBINES 
BIAS-CORRECTED OUTPUT FROM THE NCEP GEFS AND THE ENVIRONMENT CANADA ENSEMBLE 
PREDICTION SYSTEM). GUIDANCE FOR THREE AND FOUR WEEKS LEAD-TIME WAS CONSIDERED 
FROM THE CFS AND ECMWF EXTENDED MODELS. 
 
DURING THE PAST 4 WEEKS, EQUATORIAL SEA-SURFACE TEMPERATURE (SST) ANOMALIES 
HAVE BEEN ABOVE-NORMAL ACROSS MUCH OF THE WESTERN AND CENTRAL EQUATORIAL 
PACIFIC, WHILE THE SST ANOMALIES OVER THE EASTERN PACIFIC ARE BELOW ZERO. THE 
LATEST WEEKLY NINO 3.4 INDEX IS +0.5 C, WHILE THE NINO 4 INDEX IS +0.9 C, AND 
THE NINO 1+2 INDEX IS -0.8 C. THE NORTH ATLANTIC OSCILLATION HAS BEEN POSITIVE 
FOR MUCH OF THE LAST TWO MONTHS AND IS FORECAST TO REMAIN POSITIVE INTO THE 
BEGINNING OF MARCH BY NUMERICAL GUIDANCE. 
 
POSITIVE SUBSURFACE TEMPERATURE ANOMALIES EXPANDED ACROSS MUCH OF THE CENTRAL 
AND EAST-CENTRAL EQUATORIAL PACIFIC IN THE LAST MONTH ASSOCIATED WITH THE 
DOWNWELLING PHASE OF A KELVIN WAVE, WHILE NEGATIVE ANOMALIES REMAINED NEAR THE 
SURFACE IN THE EASTERN PACIFIC. ATMOSPHERIC CONDITIONS APPEARED TO INDICATE THE 
POSSIBILITY OF COUPLING OF POSITIVE SST ANOMALIES TO THE ATMOSPHERE, WITH 
NEGATIVE OUTGOING LONGWAVE RADIATION (OLR) ANOMALIES POSITIONED JUST WEST OF 
THE DATELINE REPRESENTATIVE OF ENHANCED CONVECTIVE ACTIVITY AND POSITIVE OLR 
ANOMALIES TO THE EAST OF THE DATELINE. RECENT POSITIVE WESTERLY WIND ANOMALIES 
AT 850 HPA OVER THE EAST-CENTRAL AND WESTERN PACIFIC OCEAN HAVE NOW DIMINISHED. 
THE ENSO OUTLOOK OFFICIALLY CALLS FOR ABOUT A 50 TO 60 % PROBABILITY OF THE 
DEVELOPMENT OF COUPLED EL NINO CONDITIONS. CURRENTLY, THE OVERALL ATMOSPHERE 
AND OCEAN STATE CONTINUES TO BE CONSIDERED ENSO-NEUTRAL, AND ANY FURTHER 
DEVELOPMENT OF WEAK EL NINO CONDITIONS WILL HAVE LITTLE IMPACT ON THE SEASONAL 
CLIMATE OVER NORTH AMERICA. 
 
THE TEMPERATURE OUTLOOK FOR MARCH 2015 PREDICTS ENHANCED CHANCES OF 
ABOVE-NORMAL MONTHLY MEAN TEMPERATURES WEST OF THE ROCKY MOUNTAINS, WITH 
GREATER PROBABILITIES NEAR THE COAST, AS WELL AS FOR ALASKA WITH GREATEST 
PROBABILITIES IN THE SOUTHWEST PART OF THE STATE. THE OUTLOOK PREDICTS ENHANCED 
PROBABILITIES OF BELOW-NORMAL TEMPERATURES FROM THE GREAT LAKES REGION ACROSS 
THE NORTHEAST. DYNAMICAL MODEL GUIDANCE FOR MARCH INDICATES THE PERSISTENCE OF 
A RIDGE IN THE ATMOSPHERIC CIRCULATION OVER THE NORTH PACIFIC AND ALASKA WITH 
ABOVE-NORMAL HEIGHTS AT 200 HPA OVER MUCH OF WESTERN NORTH AMERICA. MODEL 
GUIDANCE PREDICTS THE MEAN LOCATION OF A TROUGH IN THE CIRCULATION DOWNSTREAM 
OVER THE EASTERN U.S AND CANADA. THIS OUTLOOK IS SUPPORTED BY THE FORECASTS OF 
THE DYNAMICAL MODELS FROM THE NMME AND IMME FOR MARCH AS WELL AS THE FORECASTS 
FOR THE FIRST WEEK OF THE MONTH FROM THE REFORECAST-CALIBRATED GEFS AND THE 
BIAS-CORRECTED NAEFS MODELS. RECENT WEEK 3 AND 4 FORECASTS FROM THE ECMWF MODEL 
SUPPORTED THE FORECAST FOR ABOVE-NORMAL TEMPERATURES IN THE WEST AND 
BELOW-NORMAL TEMPERATURES IN THE EAST AS OF LAST WEEK. FORECASTS FROM THE CFS 
AND THIS WEEKS ECMWF MODEL FORECASTS INDICATE SUBSEASONAL VARIABILITY BRINGING 
BELOW NORMAL TEMPERATURES INTO THE PACIFIC NORTHWEST AND ABOVE-NORMAL 
TEMPERATURES INTO THE SOUTHEAST. AN INDICATION OF ENHANCED PROBABILITIES FOR 
BELOW-NORMAL TEMPERATURES IN THE NMME MODELS FOR THE SOUTHEAST WAS REMOVED AND 
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES IN THE PACIFIC NORTHWEST WERE 
REDUCED CONSIDERING UNCERTAINTY IN THIS REGION ASSOCIATED WITH THIS MOST LIKELY 
PREDICTED SUBSEASONAL VARIABILITY. OVERALL, MONTHLY FORECASTS OF 
LONGER-TIMESCALE MONTHLY AND SEASONAL VARIABILITY WAS MORE CLOSELY FOLLOWED 
THAN SUBSEASONAL FORECASTS. 
 
THE PRECIPITATION OUTLOOK FOR MARCH 2015 PREDICTS ENHANCED CHANCES OF 
ABOVE-MEDIAN PRECIPITATION FOR MUCH OF SOUTHEASTERN ALASKA WITH MEAN STORM 
TRACKS EXPECTED OVER THE TOP OF THE PREDICTED RIDGE. AN ENHANCED PROBABILITY 
FOR BELOW-MEDIAN PRECIPITATION IS INDICATED FOR THE PACIFIC COASTAL REGION IN 
THE PACIFC NORTHWEST, ASSOCIATED WITH THE PREDICTED RIDGE. AN ENHANCED 
PROBABILITY OF ABOVE-MEDIAN PRECIPITATION IS PREDICTED FOR THE U.S. SOUTHWEST 
AS WELL AS FOR THE SOUTHEAST. THE PRECIPITATION OUTLOOK IS GENERALLY SUPPORTED 
BY THE MODEL FORECASTS OF THE NMME AND IMME MODELS. ENHANCED PROBABILITIES FOR 
ABOVE-MEDIAN PRECIPITATION OVER THE SOUTHEAST WERE EXPANDED TO THE NORTH USING 
GUIDANCE FROM RECENT MONTHLY AND WEEK 3 AND 4 FORECASTS OF THE CFS. 
 
IN AREAS WHERE CLIMATE SIGNALS ARE WEAK, 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: 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. 
 
 
 
THE NEXT MONTHLY OUTLOOK...FOR APR ... WILL BE ISSUED ON THU MAR 19 2015 
 
 
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. 
 
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