LONG-LEAD SEASONAL OUTLOOKS 2005-2006

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PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EDT THU SEP 15 2005

SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS
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SEA SURFACE TEMPERATURES (SSTS) AND SUBSURFACE OCEAN TEMPERTURES ACROSS THE
EQUATORIAL PACIFIC REMAIN CLOSE TO AVERAGE ACROSS THE ENTIRE BASIN.
THIS PATTERN OF OCEAN TEMPERATURES HAS BEEN ACCOMPANIED BY STRONGER THAN AVERAGE
LOW LEVEL EASTERLY WINDS AND NEAR AVERAGE CONVECTION. DESPITE SOME DISAGREEMENT
AMONG THE STATISTICAL AND DYNAMICAL ENSO FORECASTS... CURRENT CONDITIONS AND
RECENT OBSERVED TRENDS SUPPORT A CONTINUATION OF ENSO NEUTRAL CONDITIONS THROUGH
THE END OF THE YEAR. ELSEWHERE SSTS THROUGHOUT THE TROPICAL NORTH ATLANTIC
OCEAN EXTENDING INTO THE CARIBBEAN SEA CONTINUE TO BE WELL ABOVE AVERAGE. THESE
ABNORMALLY WARM SSTS HAVE CONTRIBUTED TO A VERY ACTIVE HURRICANE SEASON. SOME
MODELING STUDIES ALSO IMPLY THAT THEY MAY ALSO PLAY A ROLE IN THE PATTERNS OF
TEMPERATURE AND PRECIPITATION ACROSS THE CONUS DURING THE UPCOMING SEASONS.

THE OUTLOOKS FOR OND 2005 THROUGH MAM 2006 ARE BASED ON A WIDE ARRAY OF
DYNAMICAL AND STATISTICAL TOOLS. OUTLOOKS FOR AMJ 2006 AND BEYOND ARE BASED
MAINLY ON TRENDS WITH SOME INPUT FROM OTHER STATISTICAL TOOLS... WITH ENSO
EXPECTED TO BE IN ITS NEUTRAL PHASE THROUGH AT LEAST SPRING 2006. THE MOST
CONFIDENT SIGNALS ARE FOR ABOVE AVERAGE TEMPERATURES DURING THE FEW SEASONS AND
AT LOCATIONS WHERE TRENDS ARE STRONG.

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BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOK

NOTE: FOR GRAPHICAL DISPLAYS OF THE FORECAST TOOLS DISCUSSED BELOW SEE:

http://www.cpc.ncep.noaa.gov/products/predictions/90day/tools/briefing

CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS

PACIFIC SSTS ALONG THE EQUATOR WERE GENERALLY NEAR THE LONG-TERM AVERAGE DURING
AUGUST WITH THE WARMEST SSTS AND LARGEST DEPARTURES OBSERVED JUST TO THE WEST OF
THE INTERNATIONAL DATE LINE. SUBSURFACE OCEAN TEMPERATURES THROUGHOUT THE
EQUATORAL PACIFIC WERE SLIGHTLY ABOVE AVERAGE IN THE WESTERN AND FAR EASTERN
PACIFIC AND 1-2 DEGREES CELSIUS BELOW AVERAGE NEAR 100 M DEPTH BETWEEN 150W AND
100W. ATMOSPHERIC INDICATORS SUCH AS THE LOW LEVEL WINDS AND CONVECTION IN
THE EQUATORIAL PACIFIC ALSO REMAIN CLOSE TO AVERAGE AND SUGGEST... TOGETHER WITH
THE OCEAN STATE ... THAT NEUTRAL ENSO CONDITIONS WILL LIKELY PREVAIL IN THE NEXT
FEW MONTHS. THERE IS AN EXTENSIVE AREA OF ABOVE NORMAL SSTS IN THE (SUB)TROPICAL
ATLANTIC OCEAN AND THE CARIBBEAN SEA. MODEL INDICATIONS FROM SOME EXPERIMENTAL
RUNS INDICATE THESE VERY WARM ATLANTIC SSTS MAY CONTRIBUTE TO RIDGING OVER THE
WESTERN CONUS.
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PROGNOSTIC DISCUSSION OF SST FORECASTS

THE CONSENSUS OF SEVERAL MODELS USED AT CPC SHOWS SEASONAL MEAN NINO 3.4 SST
ANOMALIES REMAINING VERY CLOSE TO THE LONG TERM AVERAGES THROUGH THE WINTER AND
THE SPRING. SPREAD AMONG THE INDIVIDUAL TOOLS HAS DECREASED THIS MONTH...
RANGING FROM +0.6 FROM THE CCA TO -0.4 FROM THE CFS. THIS DECREASE IN SPREAD
INCREASES THE CONFIDENCE THAT SSTS ACROSS THE TROPICAL PACIFIC WILL REMAIN NEAR
AVERAGE THROUGH THE EARLY PART OF 2006.

PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS

THE OUTLOOK FOR OND 2005 THROUGH MAM 2006 IS BASED ON THE MULTI-MODEL
ENSEMBLE FROM IRI... THE CFS... AND STATISTICAL TOOLS... INCLUDING CCA... SMLR
AND OCN. INPUT FROM CDC MODELS - WHICH FAVORS WARM AND DRY CONDITIONS OVER THE
WESTERN TWO-THIRDS OF THE NATION - WAS CONSULTED. ECCA WAS USED FOR OND. OCN
IS THE PRIMARY TOOL EXPLICITLY USED FROM MAM THROUGH OND 2006. BECAUSE ENSO IS
WEAK ALL FORECASTS REFLECT INTERDECADAL TREND MORE THAN ANY OTHER FACTOR. A
NEW FORECAST TOOL HAS BEEN DEVELOPED WHICH COMBINES THE CCA - THE OCN - THE SMLR
AND A 15-MEMBER ENSEMBLE MEAN FROM THE CFS - USING THE KNOWN SKILL OF THE
VARIOUS TOOLS TO FORM A WEIGHTED AVERAGE. THIS TOOL - CALLED CON - HELPS TO
REDUCE THE UNCERTAINTY WHICH FORECASTERS CONFRONT WHEN THEY TRY TO SUBJECTIVELY
COMBINE FORECAST TOOLS. THIS TOOL HAS BEEN USED IN THE TEMPERATURE AND
PRECIPITATION FORECASTS THIS TIME. VERIFICATION OF THE TOOL OVER FORECASTS
FROM THE 1995-2005 PERIOD INDICATE THAT THE TOOL SHOULD IMPROVE TEMPERATURE
FORECASTS OVER THE CONUS. PRECIPITATION FORECASTS FROM THE CON HAVE NOT YET
BEEN VERIFIED AND IT IS - THEREFORE - USED MUCH MORE CONSERVATIVELY THAN IT
WAS FOR TEMPERATURE.
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PROGNOSTIC DISCUSSION OF OUTLOOKS - OND 2005 TO OND 2006

TEMPERATURE:

THE MAJOR CHANGE FROM LAST MONTH TO THE OND 2005 FORECAST WAS AN EXPANSION OF
THE REGION OF ABOVE AVERAGE TEMPERATURES THROUGHOUT THE WEST... ALTHOUGH THE
REGION IN THE PACIFIC NORTHWEST WAS SHIFTED SOUTH. ALSO THE REGION OF ABOVE
AVERAGE TEMPERATURES IN ALASKA WAS EXPANED TO ENCOMPASS MUCH OF CENTRAL AND
WESTERN ALASKA. THE EXPANSION IN THE WEST WAS CONSISTENT WITH MANY OF THE
MODELS FORCED BY WARM SUBTROPICAL ATLANTIC SSTS. DURING THE WINTER SEASONS...
MODIFICATIONS INCLUDED AN EXPANSION OF ABOVE AVERAGE TEMPERATURES IN THE WEST
DURING NDJ AND THE DECREASE IN ABOVE AVERAGE TEMPERATURES DURING DJF AND JFM
OVER THE MIDWEST AND NORTHEAST. THE CHANGES IN THE MIDWEST AND NORTHEAST
REFLECT THE CONTINUED UNCERTAINTY WITH POTENTIAL PHASE OF THE NAO DURING THE
WINTER AS WELL AS CONFLICTS BETWEEN OCN - WHICH FAVORS ABOVE AVERAGE
TEMPERATURES IN THESE REGIONS - AND INPUT FROM CDC... WHICH FAVORED AVERAGE TO
BELOW AVERAGE.

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PRECIPITATION:

CHANGES FROM LAST MONTHS FORECASTS ARE LESS EXTENSIVE FOR PRECIPITATION THAN THEY
WERE FOR TEMPERATURE. FOR OND... SIGNALS FOR CONTINUED WETNESS OVER FLORIDA WERE
WEAKER... AND THIS ABOVE AVERAGE AREA WAS REMOVED. AN EXTENSIVE AREA OF BELOW
AVERAGE PRECIPITATION WAS INSERTED OVER THE THE SOUTHWEST... AS THE ECCA... THE
IRI MULTI-MODEL... THE CFS... THE SMLR... AND THE CDC INPUT ALL FAVORED BELOW
AVERAGE PRECIPITATION IN THE REGION. THE FORECASTS FOR BELOW AVERAGE
PRECIPITATION IS CONTINUED IN PARTS OF THE SOUTHWEST THROUGH DJF 2005-2006...
AS THE SMLR... THE CFS... AND INPUT FROM CDC CONTINUE TO SIGNAL DRIER THAN
AVERAGE CONDITIONS. THE ONLY OTHER CHANGE TO THE SUITE OF SEASONAL PRECIPITATION
OUTLOOKS OCCURRED IN FLORIDA... WHERE AN ENHANCED REGION OF ABOVE AVERAGE
RAINFALL DURING JJA 2006 WAS INDICATED BY THE LONG TERM TREND .

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PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EDT THU SEPTEMBER 15 2005
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30-DAY OUTLOOK DISCUSSION FOR OCTOBER 2005

SEA SURFACE TEMPERATURES ACROSS THE EQUATORIAL PACIFIC CONTINUE TO REMAIN
NEAR AVERAGE... AS ARE THE PATTERNS OF CONVECTION AND THE LOW LEVEL WINDS.
MJO ACTIVITY HAS INTENSIFIED SOMEWHAT DURING THE LAST TWO MONTHS.
FORECASTS OF OCEAN TEMPERATURES ACROSS THE TROPICAL PACIFIC INDICATE
THAT NEAR-AVERAGE CONDITIONS WILL PREVAIL ACROSS THIS REGION FOR AT LEAST THE
NEXT SEASON. THEREFORE FORCING FROM THE TROPICS DUE TO THE ENSO CYCLE IS NOT
EXPECTED TO PLAY A ROLE IN THE CLIMATE DURING OCTOBER.

THE LONG-LEAD OUTLOOK FOR SEPTEMBER IS BASED ON THE STATISTICAL TOOLS CCA -
OCN AND SMLR... WITH SOME CONSIDERATION GIVEN TO THE MONTHLY FORECAST FROM
THE CFS. ABOVE-AVERAGE TEMPERATURES ARE INDICATED BY THE OCN FOR PARTS OF
THE SOUTHWEST. THE CCA AND SMLR ALSO INDICATE ABOVE AVERAGE TEMPERATURES
FOR THAT REGION. THE SMLR INDICATES BELOW AVERAGE TEMPERATURES IN THE SOUTH
CENTRAL PLAINS THAT WAS DISREGARDED SINCE IT WAS NOT SUPPORTED IN ANY OTHER
TOOL. THE CCA... AND TO A LESSER EXTENT THE OCN INDICATED ABOVE NORMAL
TEMPTERATURES OVER COASTAL ALASKA INCLUDING THE ALEUTIANS... WHICH IS ALSO
SUPPORTED BY ABNORMALLY WARM SSTS ALONG THE SOUTH ALASKAN COAST AND IN THE
BERING SEA.

THE ONLY STATISTICALLY SIGNIFICANT AREA OF PRECIPITATION DEPARTURES FROM
THE OCN IS WETTER-THAN-AVERAGE CONDITIONS FOR FLORIDA. THE SMLR HAS A FEW AREAS
WHICH ARE MARGINALLY SIGNIFICANT...BUT THEY WERE DISREGARDED SINCE THERE WAS A
LACK OF SUPPORT BY THE OTHER TOOLS. THE CCA DOES NOT INDICATE ANY AREA OF
SIGNIFICANT DEPARTURES..BUT THE SIGN OF THE DEPARTURES OVER FLORIDA AGREED WITH
THE OCN...WHICH IS REFLECTED IN THE OUTLOOK. WETTER-THAN-AVERAGE FOR FLORIDA IS
ALSO CONSISTENT WITH THE EXPECTED CONTINUATION OF AN ACTIVE HURRICANE SEASON.
NO AREAS WERE DEEMED TO BE SIGNIFICANT OVER ALASKA AND THE ENTIRE STATE WAS
LEFT AS EC.