PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EDT THU SEP 30 2004

30-DAY OUTLOOK DISCUSSION FOR OCTOBER 2004
                                                                               .
THE UPDATED FORECAST FOR OCTOBER IS BASED ON FORECASTS FROM THE CFS...CCA...
OCN...SMLR COMBINED WITH SHORT TERM ANOMALIES DERIVED FROM THE DYNAMICAL
SHORT RANGE MODELS AVAILABLE AT NCEP.  THE EFFECTS OF WARMER THAN NORMAL SEA 
SURFACE TEMPERATURES ALONG THE WEST COAST OF NORTH AMERICA FROM ALASKA SOUTHWARD 
THROUGH CALIFORNIA WAS ALSO CONSIDERED.  COASTAL SEA SURFACE TEMPERATURE
ANOMALIES CONTINUE TO BE ABOVE AVERAGE... BUT HAVE DECREASED IN MAGNITUDE SINCE
THE MIDDLE OF SEPTEMBER.

ABOVE NORMAL SSTS CONTINUE ACROSS THE CENTRAL EQUATORIAL PACIFIC... WITH 
SSTS MORE THAN 1 DEGREE C ABOVE NORMAL OBSERVED BETWEEN 165E AND 140W.  
IN CONTRAST EQUATORIAL SSTS IN THE EASTERN PACIFIC CONTINUE TO AVERAGE 
NORMAL OR SLIGHTLY BELOW NORMAL FROM THE SOUTH AMERICAN COAST TO ABOUT 
135 W.  THE OCEANIC THERMOCLINE ACROSS THE EQUATORIAL PACIFIC CONTINUES 
TO BE DEEPER THAN NORMAL ON AVERAGE... WITH MODULATIONS DUE TO EASTWARD 
MOVING KELVIN WAVES. TROPICAL INTRASEASONAL ACTIVITY CONTINUES TO PLAY
A MAJOR ROLE OVER THE INDIAN AND PACIFIC BASINS.  GENERALLY NEAR NORMAL
LOW-LEVEL WINDS ARE OBSERVED ACROSS MUCH OF THE EQUATORIAL PACIFIC.
CONVECTION ALSO CONTINUES TO BE MODULATED BY THE INTRASEASONAL ACTIVITY... 
WITH ENHANCED CONVECTION OBSERVED OVER THE CENTRAL INDIAN OCEAN AND 
SUPPRESSED CONVECTION OBSERVED OVER INDONESIA DURING LATE SEPTEMBER.  
  
ALTHOUGH A CONSENSUS OF MODELS INDICATES THAT AT LEAST WEAK EL NINO CONDITIONS
WILL CONTINUE INTO EARLY NEXT YEAR... NO CLEAR SIGNALS FROM THE TROPICAL 
PACIFIC ARE EXPECTED TO INFLUENCE TEMPERATURE OR PRECIPITATION OVER THE CONUS 
AND ALASKA DURING OCTOBER SINCE THE ENSO INFLUENCE ON U.S. TEMPERATURE AND 
PRECIPITATION PATTERNS IS MORE SIGNIFICANT DURING THE WINTER AND SPRING AND
ALSO HAS MORE APPLICABILITY ON THE SEASONAL TIME SCALE.   

THE UPDATED TEMPERATURE OUTLOOK FOR OCTOBER FEATURES THE LIKELIHOOD OF ABOVE 
NORMAL TEMPERATURES IN THE SOUTHWEST AND SOUTH FLORIDA... BOTH INDICATED BY 
OCN.  BELOW NORMAL TEMPERATURES ARE FAVORED IN THE NORTHERN PLAINS FROM MONTANA 
EASTWARD TO MINNESOTA AND SOUTHWARD TO SOUTH DAKOTA... AND ALSO OVER TEXAS... 
LOUISIANA... AND SOUTHERN OKLAHOMA.  BOTH OF THESE REGIONS ARE INDICATED BY THE 
CFS.  THIS FORECAST IS SIMILAR TO THE 0.5 MONTH LEAD...AS THE SHORT RANGE MODELS 
ARE NOT INDICATING THAT ANY PARTICULAR PATTERN WILL BECOME THE FAVORED ONE FOR 
THE MONTH.  

THE MAIN TEMPERATURE CHANGE BETWEEN THE 0.5 MONTH LEAD AND THIS FORECAST IS
OVER ALASKA... WHERE THE TRADITIONAL OCN TOOL GIVES A SLIGHT INDICATION OF 
WARMER THAN NORMAL TEMPERATURES OVER WESTERN ALASKA... AND ABOVE NORMAL SST 
ANOMALIES OVER THE BERING SEA WOULD ALSO SUPPORT ABOVE AVERAGE TEMPERATURES IN 
THIS REGION DURING OCTOBER.  HOWEVER MOST SHORT RANGE DYNAMICAL MODELS ARE 
INDICATING BELOW NORMAL TEMPERATURES OVER PARTS OF ALASKA DURING THE FIRST HALF 
OF THE MONTH. THIS FORECAST AND THE FACT THAT TEMPERATURES HAVE BEEN RUNNING 
BELOW NORMAL OVER MUCH OF ALASKA SINCE THE MIDDLE OF SEPTEMBER HAS RESULTED IN 
A LARGE CHANGE TO THE 0.5 MONTH LEAD FORECAST... WITH BELOW NORMAL TEMPERATURES 
NOW EXPECTED OVER THE NORTHERN AND WESTERN PARTS OF ALASKA AND WITH EC FORECAST 
FOR THE SOUTHERN AND COASTAL PARTS.

THE PRECIPITATION FORECAST INDICATIONS ARE AS USUAL MUCH WEAKER THAN FOR 
TEMPERATURE.  THE UPDATED FORECAST CONTINUES TO FEATURE ABOVE MEDIAN 
PRECIPITATION OVER TEXAS AND FLORIDA.  EACH REGION WAS ENLARGED SLIGHTLY AS SHORT 
AND MEDIUM RANGE INDICATIONS FAVOR ABOVE MEDIAN RAINFALL IN BOTH AREAS.  A BELOW 
MEDIAN AREA WAS ADDED IN THE OHIO VALLEY... ALSO CONSISTENT WITH THE SHORT AND 
MEDIUM RANGE GUIDANCE AND WITH THE OCTOBER - DECEMBER SEASONAL OUTLOOK.

FORECASTER: M. HALPERT 

NOTE - WITHIN THE VALID PERIOD OBSERVATIONS AND SHORT AND MEDIUM RANGE
FORECASTS SHOULD BE CONSULTED.

NOTE -  AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL
PROBABILTIES) ARE NOW LABELED EC (EQUAL CHANCES). 
  
NOTE - THE NEXT 0.5 MONTH LEAD-TIME MONTHLY OUTLOOK FOR NOVEMBER 2004 WILL BE ISSUED
THURSDAY OCT 21 2004.
  
NORMALS ARE BASED ON THE 1971-2000 PERIOD.

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