PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU OCT 20 2016

30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2016

DURING THE PAST MONTH, CONDITIONS OVER THE TROPICAL PACIFIC HAVE BECOME MORE 
CONSISTENT WITH A DEVELOPING LA NINA EVENT. COUPLED WITH THE CONSENSUS AMONG 
VARIOUS DYNAMICAL AND STATISTICAL TOOLS, ODDS ARE NOW TILTED IN FAVOR OF LA 
NINA OVER THE COMING MONTHS. AS A RESULT, STATISTICAL GUIDANCE THAT USES ENSO 
AS A PREDICTOR IS STRONGLY CONSIDERED FOR THIS OUTLOOK.

MJO INDICES (CPC VELOCITY POTENTIAL AND RMM) INDICATE NO APPRECIABLE, COHERENT 
MJO ACTIVITY DURING THE PAST MONTH AND FORECASTS DO NOT DEPICT CLEAR, LONG TERM 
STRENGTHENING AT THE CURRENT TIME. THEREFORE, THE MJO DOES NOT INFLUENCE THE 
NOVEMBER OUTLOOK AT PRESENT. 

THE NOVEMBER 2016 TEMPERATURE AND PRECIPITATION OUTLOOKS ARE PRIMARILY BASED ON 
CALIBRATED DYNAMICAL GUIDANCE, ALONG WITH STATISTICAL GUIDANCE THAT EMPHASIZES 
ENSO AND LONG-TERM TRENDS. COASTAL SST ANOMALIES ALSO PLAYED A SMALL ROLE IN 
THE OUTLOOK, PRIMARILY FOR AREAS NEAR ALASKA.

THE NOVEMBER TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL TEMPERATURES FOR MOST OF 
THE FORECAST DOMAIN. THE ENSO SIGNAL AND LONG-TERM TRENDS TOGETHER PLACE THE 
HIGHEST PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES OVER THE SOUTHWESTERN AND 
SOUTH-CENTRAL U.S. EXTENDING NORTHEASTWARD THROUGH THE UPPER MIDWEST, GREAT 
LAKES, AND NORTHEAST. LONG-TERM TRENDS ARE STRONG OVER ALASKA. EQUAL-CHANCES OF 
BELOW-, ABOVE-, AND NEAR-NORMAL TEMPERATURES IS INDICATED OVER A SMALL PORTION 
OF INTERIOR ALASKA, THE PACIFIC NORTHWEST, AND THE FAR SOUTHEASTERN PORTION OF 
THE CONUS. THE CALIBRATED GUIDANCE FROM THE NMME, INITIALIZED EARLY THIS MONTH, 
STRONGLY SUPPORTS THIS PATTERN. MORE RECENTLY INITIALIZED GUIDANCE FROM THE CFS 
FAVORS A VERY WARM SOLUTION ACROSS MOST OF NORTH AMERICA. 

INTERESTINGLY, THIS PATTERN IS GENERALLY AN EXTENSION OF THE CURRENT WEEK-2 
FORECAST, SUGGESTING A FAIRLY PERSISTENT PATTERN. RECENT WEEK 3/4 GUIDANCE 
GENERALLY SUPPORTS THE CONTINUATION OF THIS PATTERN THROUGH THE FIRST PART OF 
THE MONTH, THOUGH RECENT RUNS OF THE CFS AND THE ECMWF ENSEMBLES SUGGEST THAT 
SOME PATTERN CHANGE MAY EVOLVE DURING THE MIDDLE PORTION OF THE MONTH. INDEED, 
THEREIN LIES THE KEY UNCERTAINTY IN THE TEMPERATURE FORECAST. THE RECENT 
PATTERN HAS BEEN FAIRLY PERSISTENT OVER NORTH AMERICA, BUT AS THE SEASONAL 
CYCLE UNFOLDS, THE PATTERN IS EXPECTED TO EVOLVE ON LOW-FREQUENCY TIMESCALES 
TOWARD SOMETHING MORE AKIN TO THE LA NINA EXTRATROPICAL RESPONSE, WITH MORE 
SEASONABLE TEMPERATURES AND EVEN BELOW-NORMAL TEMPERATURES ACROSS PARTS OF THE 
NORTHERN CONUS. IN REALITY THIS CHANGE (IF IT HAPPENS) WILL OCCUR ACROSS A 
SERIES OF SYNOPTIC EVENTS, THE TIMING OF WHICH IS DIFFICULT TO CAPTURE IN A 
0.5-MONTH LEAD MONTHLY FORECAST.

THE PRECIPITATION OUTLOOK IS BASED LARGELY ON CORRELATIONS WITH ENSO, WHICH 
EVEN IN NOVEMBER BEGIN TO SHOW A FAIRLY CANONICAL LA NINA PATTERN. ABOVE-MEDIAN 
PRECIPITATION IS FAVORED OVER THE NORTHERN ROCKIES EXTENDING TO THE PACIFIC 
NORTHWEST, WHILE BELOW-MEDIAN PRECIPITATION IS FAVORED ACROSS MUCH OF THE 
SOUTHERN TIER OF THE CONUS. THIS PATTERN IS ALSO STRONGLY SUPPORTED BY THE 
CALIBRATED NMME GUIDANCE AND RECENT RUNS OF THE CFS. DURING THE LAST WEEK OF 
OCTOBER, ABOVE-MEDIAN PRECIPITATION IS FAVORED OVER MUCH OF THE WESTERN CONUS. 
HOWEVER, THERE IS LITTLE REASON TO BELIEVE THAT THIS SIGNAL WILL PERSIST OVER 
THE SOUTHWEST AND SOUTH-CENTRAL U.S. INTO NOVEMBER GIVEN THE LOW-FREQUENCY 
BACKGROUND STATE. AS WITH THE TEMPERATURE OUTLOOK, PROBABILITIES ARE MODEST 
ACROSS THE FORECAST DOMAIN GIVEN THE AFOREMENTIONED UNCERTAINTY.


FORECASTER: STEPHEN BAXTER


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 NOV WILL BE ISSUED ON MON OCTOBER 31 2016


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

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