PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EST THU DEC 15 2016

30-DAY OUTLOOK DISCUSSION FOR JANUARY 2017

THE JANUARY 2017 TEMPERATURE AND PRECIPITATION OUTLOOKS ARE BASED ON DYNAMICAL 
MODEL OUTPUTS, STATISTICAL TOOLS, TYPICAL PATTERNS ASSOCIATED WITH TROPICAL SST 
VARIABILITY, AND THE LIKELY STATES OF PATTERNS OF EXTRATROPICAL VARIABILITY. LA 
NINA CONDITIONS CONTINUE OVER THE TROPICAL PACIFIC, AND ARE EXPECTED TO 
CONTINUE THROUGH JANUARY 2017, THOUGH IMPACTS ON THE MONTHLY TIMESCALE FROM 
ENSO ARE LESS ROBUST THAN SEASONAL IMPACTS. CLIMATE SIGNALS ASSOCIATED WITH LA 
NINA ARE CONSIDERED AS A PORTION OF THE OUTLOOK. 

THE MJO IS NOT CURRENTLY ACTIVE, AND THE UNCERTAINTY FOR INTRASEASONAL 
VARIABILITY IS HIGH, SO THE MJO DID NOT PLAY A ROLE IN THE OUTLOOK. ITS 
EVOLUTION WILL BE CLOSELY MONITORED FOR THE REVISED OUTLOOK AT THE END OF 
DECEMBER. 

THE DYNAMICAL MODEL OUTLOOKS FOR JANUARY 2017 EXHIBITED GOOD AGREEMENT, WHERE 
AS LAST MONTH THE OUTLOOKS FOR DECEMBER HAD BETTER AGREEMENT, SO THE CONFIDENCE 
IN THE OUTLOOK IS SLIGHTLY LOWER, RESULTING IN LOW TO MODERATE COVERAGE. LA 
NINA CONDITIONS WOULD FAVOR ABOVE NORMAL TEMPERATURES OVER THE SOUTHERN CONUS 
WITH BELOW NORMAL TEMPERATURES OVER MUCH OF THE NORTHERN CONUS. THE SPATIAL 
COVERAGE OF WHERE BELOW NORMAL TEMPERATURES ARE FAVORED OVER THE NORTHERN 
ROCKIES AND NORTHERN GREAT PLAINS IS SMALLER THAN A TYPICAL SEASONAL FOOTPRINT 
OF LA NINA, DUE TO LOWER PREDICTABILITY AND DYNAMICAL MODEL GUIDANCE. SOME 
STATISTICAL TOOLS FAVOR BELOW NORMAL TEMPERATURES EXTENDING INTO NORTHERN 
COLORADO. SOME DYNAMICAL MODELS INDICATE A SLIGHT TILT TOWARD A NEGATIVE ARCTIC 
OSCILLATION THROUGHOUT THE WINTER, WHICH FAVORS PERIODS OF COLDER AIR MOVING 
SOUTHWARD OVER THE GREAT PLAINS, SO PROBABILITIES FOR ABOVE NORMAL TEMPERATURES 
ARE LOWER THAN INDICATED IN MODEL GUIDANCE OVER THE GREAT PLAINS AND 
MID-ATLANTIC. ABOVE NORMAL SSTS FAVOR ABOVE NORMAL TEMPERATURES FOR WESTERN 
ALASKA AND THE ALEUTIANS.

THE PRECIPITATION OUTLOOK FOR JANUARY 2017 REFLECTS CALIBRATED NMME OUTPUT AND 
IS CONSISTENT WITH TRADITIONAL LA NINA IMPACTS DURING DJF AND JFM. COVERAGE AND 
PROBABILITIES FOR THE CATEGORIES ARE LOWER THAN IF LA NINA WAS THE ONLY FACTOR, 
AS SIGNALS IN THE DYNAMICAL MODELS ARE WEAKER, AND LA NINA IMPACTS ON A SINGLE 
MONTH OF A SEASON ARE LESS PRONOUNCED THAN IMPACTS ON AN ENTIRE SEASON. BELOW 
MEDIAN PRECIPITATION IS FAVORED FOR THE SOUTHERN CONUS, WITH ABOVE MEDIAN 
PRECIPITATION FAVORED ALONG THE ROCKIES AND OVER THE GREAT LAKES REGION, WITH A 
MORE ACTIVE NORTHERN STORM TRACK. ABOVE NORMAL SSTS, BELOW NORMAL SEA ICE 
COVERAGE IN THE BERING SEA, AND MODEL GUIDANCE FAVOR ABOVE MEDIAN PRECIPITATION 
FOR WESTERN ALASKA. 


FORECASTER: MATTHEW ROSENCRANS


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 JAN WILL BE ISSUED ON SAT DECEMBER 31 2016


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

$$