PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830AM EST THURSDAY JAN 17 2013

30-DAY OUTLOOK DISCUSSION FOR FEBRUARY 2013

ENSO-NEUTRAL CONDITIONS CONTINUED DURING DECEMBER 2012. THE MOST RECENT WEEKLY 
SST ANOMALY FOR THE NINO 3.4 REGION IS -0.6 C HAVING COOLED DURING THE LAST 
MONTH. SUBSURFACE EQUATORIAL HEAT CONTENT TO 300 METERS DEPTH CONTINUED TO 
DECREASE IN DECEMBER 2012. OUTGOING LONGWAVE RADIATION ANOMALIES ARE NEGATIVE 
OVER THE MARITIME CONTINENT INDICATING ENHANCED CONVECTION AND POSITIVE OVER 
THE CENTRAL PACIFIC WHERE CONVECTION IS SUPPRESSED. ENSO-NEUTRAL CONDITIONS ARE 
EXPECTED TO PERSIST THROUGH FEBRUARY. THERE IS CURRENTLY AN ACTIVE MJO, WHICH 
HAS CONTRIBUTED TO THE PATTERNS OF ANOMALOUS CONVECTION DESCRIBED ABOVE. 
EVOLUTION OF MJO-RELATED CONVECTION MAY IMPACT THE FEBRUARY TEMPERATURE AND 
PRECIPITATION OVER NORTH AMERICA. A SUDDEN STRATOSPHERIC WARMING (SSW) BEGAN 
JANUARY 6 AND IS EXPECTED TO CONTINUE INTO FEBRUARY. SSW HAS BEEN ASSOCIATED 
WITH SUBSEQUENT TROPOSPHERIC ANOMALIES AND CHANGES TO THE TEMPERATURE PATTERN 
OVER NORTH AMERICA, INCLUDING BELOW NORMAL TEMPERATURES IN THE EASTERN U.S.

THE TEMPERATURE OUTLOOK FOR FEBRUARY 2013 INDICATES ELEVATED PROBABILITIES OF 
BELOW NORMAL TEMPERATURES FROM THE NORTHERN ROCKIES ACROSS THE NORTHERN PLAINS 
INTO THE WESTERN GREAT LAKES REGION AND UPPER MISSISSIPPI VALLEY. THE 
PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE ELEVATED FROM CALIFORNIA INTO 
THE SOUTHWEST, AS WELL AS FOR NORTHERN ALASKA. THE FORECAST TEMPERATURE PATTERN 
FOR FEBRUARY IS SUPPORTED BY DYNAMICAL MODEL FORECASTS FROM THE NCEP CLIMATE 
FORECAST SYSTEM (CFSV2) AND THE MODELS OF THE NATIONAL MULTI-MODEL ENSEMBLE 
(NMME) AND THE INTERNATIONAL MULTI-MODEL ENSEMBLE (IMME), INCLUDING THE 
FRACTION OF ENSEMBLE MEMBERS FROM THE NMME AND CFSV2 FORECASTING ABOVE AND 
BELOW NORMAL TEMPERATURES.

THE PRECIPITATION OUTLOOK FOR FEBRUARY 2013 INDICATES ELEVATED PROBABILITIES 
FOR BELOW MEDIAN PRECIPITATION FOR THE SOUTHWEST QUARTER OF THE U.S. AND ALONG 
THE GULF COAST. PROBABILITIES OF ABOVE MEDIAN PRECIPITATION FOR FEBRUARY EXTEND 
ACROSS THE NORTHERN PLAINS TO THE MISSISSIPPI RIVER. ELEVATED PROBABILITIES FOR 
ABOVE MEDIAN PRECIPITATION ARE ALSO INDICATED FOR NORTHWEST ALASKA. THE 
FORECAST PRECIPITATION PATTERN FOR FEBRUARY IS SUPPORTED BY DYNAMICAL MODEL 
FORECASTS FROM THE CFSV2 AND THE MODELS OF THE NMME AND IMME.

AREAS WHERE THE LIKELIHOODS OF MONTHLY MEAN TEMPERATURE AND MONTHLY ACCUMULATED 
PRECIPITATION AMOUNTS ARE SIMILAR TO CLIMATOLOGICAL PROBABILITIES OF BELOW, 
NEAR AND ABOVE NORMAL TEMPERATURE OR PRECIPITATION ARE SHOWN AS EQUAL CHANCES 
(EC).

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 
VERSION 2 (CFSV2) AND FOR ZERO-LEAD UPDATE FORECASTS THE NCEP GLOBAL ENSEMBLE 
FORECAST SYSTEM (GEFS). THE EARLIER VERSION OF THE CFS MODEL WAS DISCONTINUED 
AS OF OCTOBER, 2012. 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 FEB WILL BE ISSUED ON THU JANUARY 31 2013


THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD.

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