PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EDT SAT SEP 30 2006

30-DAY OUTLOOK DISCUSSION FOR OCTOBER 2006

EQUATORIAL SEA SURFACE TEMPERATURES IN THE EASTERN AND CENTRAL PACIFIC OCEAN 
INCREASED DURING AUGUST AND MUCH OF SEPTEMBER... WITH SST ANOMALIES GREATER 
THAN +0.5 DEGREE C OBSERVED ACROSS MOST OF THE EQUATORIAL PACIFIC.   SST 
ANOMALIES GREATER THAN 1 DEGREE C COVER MOST OF THE AREA ALONG THE EQUATORIAL 
PACIFIC FROM 160E TO 85W.   THE BASIN-WIDE UPPER OCEAN HEAT CONTENT ALSO HAS 
CONTINUED TO INCREASE DURING THIS SAME PERIOD.  POSITIVE UPPER-OCEAN HEAT 
CONTENT ANOMALIES OFTEN PRECEDE WARM EPISODES.   LOW-LEVEL (850-HPA) EASTERLY 
WINDS WERE WEAKER THAN NORMAL ACROSS MOST OF THE EQUATORIAL PACIFIC DURING 
AUGUST... AND THE SOUTHERN OSCILLATION INDEX (SOI) WAS NEGATIVE FOR THE FOURTH 
CONSECUTIVE MONTH.  THESE OCEANIC AND ATMOSPHERIC ANOMALIES WHEN CONSIDERED 
COLLECTIVELY... ARE CONSISTENT WITH DEVELOPING WARM EPISODE (EL NINO) 
CONDITIONS ACROSS THE TROPICAL PACIFIC.   THE LATEST NCEP COUPLED FORECAST 
SYSTEM (CFS) PREDICTIONS... AS WELL AS A MAJORITY OF THE OTHER AVAILABLE 
STATISTICAL AND COUPLED MODEL PREDICTIONS ... ARE FAVORING EL NINO CONDITIONS 
THROUGH THE UPCOMING NORTHERN HEMISPHERE WINTER AND INTO SPRING 2007.

THE REVISED MONTHLY TEMPERATURE OUTLOOK FOR OCTOBER CALLS FOR ABOVE-NORMAL 
TEMPERATURES OVER MOST OF THE SOUTH-CENTRAL AND SOUTHEASTERN CONUS... IN 
ADDITION TO MOST OF ALASKA (EXCLUDING THE PANHANDLE REGION).  THE REMAINING 
PORTIONS OF THE CONUS AND ALASKA ARE FORECAST TO HAVE EQUAL CHANCES (EC) OF 
BELOW - NEAR - AND ABOVE AVERAGE TEMPERATURES.  THIS FORECAST IS BASED 
PRIMARILY ON EXTENDED RANGE DYNAMICAL MODEL OUTPUT WHICH COVERS THE FIRST TWO 
WEEKS OF OCTOBER.  THE MAJORITY OF DYNAMICAL MODELS PREDICT A MEAN TROUGH OVER 
THE FAR WESTERN CONUS... AND A MEAN RIDGE CENTERED OVER THE EAST-CENTRAL STATES 
FOR MOST OF THIS PERIOD.  THE CAS STATISTICAL TOOL GAVE MODEST SUPPORT FOR THE 
RELATIVE WARMTH ANTICIPATED IN THE SOUTHERN CONUS. 

THE REVISED MONTHLY PRECIPITATION OUTLOOK FOR OCTOBER CALLS FOR ABOVE-NORMAL 
AMOUNTS OF PRECIPITATION FROM THE INTERIOR SOUTHWEST NORTHEASTWARD ACROSS THE 
SOUTHERN HALF OF THE ROCKIES TO THE CENTRAL PLAINS AND UPPER MISSISSIPPI 
VALLEY.  THE PRECIPITATION FORECAST IS ALSO BASED PRIMARILY ON EXTENDED RANGE 
MODEL GUIDANCE AND THE LATEST CAS STATISTICAL FORECAST.  WETTER THAN AVERAGE 
CONDITIONS ARE EXPECTED TO ACCOMPANY AN UPPER-LEVEL TROUGH AND ASSOCIATED 
CUTOFF LOW ACROSS THE SOUTHWEST.  THIS AREA OF WETNESS IS PREDICTED TO EXTEND 
NORTHEASTWARD INTO THE MID-SECTION OF THE NATION AND MERGE WITH GENERAL 
STORMINESS AND INCREASED FRONTAL SYSTEM ACTIVITY ON THE WESTERN SIDE OF THE 
UPPER RIDGE ANTICIPATED OVER THE EAST-CENTRAL CONUS.  ALL REMAINING AREAS ARE 
FORECAST TO HAVE EQUAL CHANCES (EC) OF BELOW - NEAR - OR ABOVE AVERAGE AMOUNTS 
OF PRECIPITATION.   THE WELL-DEFINED PATTERNS OF BOTH PRECIPITATION AND 
TEMPERATURE THAT TYPICALLY ACCOMPANY AN EL NINO TEND TO MATERIALIZE FURTHER 
INTO THE COLD SEASON... AND WERE NOT CONSIDERED FOR THIS UPDATE.

FORECASTER: A. ARTUSA

NOTES - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL 
PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES).

THE NEXT MONTHLY OUTLOOK... FOR NOVEMBER 2006... WILL BE ISSUED ON THU OCT 19 
2006

THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD.

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