30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2004
Posted: Thu Nov 04, 2004 11:35 am
30-DAY OUTLOOK DISCUSSION FOR NOVEMBER 2004
.
THE UPDATED FORECAST FOR NOVEMBER IS BASED PRIMARILY ON THE GUIDANCE FOR THE
FIRST TWO WEEKS OF THE MONTH FROM THE DYNAMIC MODELS COMBINED WITH INPUT FROM
THE SKILL-MASKED CFS AND SUPPORT FROM CCA AND OCN IN THE SOUTHWEST.
CURRENT OBSERVATIONS INDICATE THAT WEAK WARM EPISODE CONDITIONS (EL NINO)
CONTINUE OVER THE EQUATORIAL PACIFIC AND A MAJORITY OF SEA SURFACE TEMPERATURE
(SST) PREDICTION TOOLS INDICATE THAT AT LEAST WEAK EL NINO CONDITIONS WILL
CONTINUE FROM THIS FALL THROUGH THE FIRST FEW MONTHS OF 2005. THERE IS A CHANCE
THAT THE EL NINO COULD STRENGTHEN TO MODERATE INTENSITY AND A SMALLER CHANCE
THAT IT WILL WEAKEN BACK TO NEUTRAL STATUS. HOWEVER THE CONSENSUS AMONG
STATISTICAL AND DYNAMICAL MODEL PREDICTIONS CONTINUES TO INDICATE THAT
THREE-MONTH AVERAGED SST ANOMALIES IN THE CENTRAL EQUATORIAL PACIFIC AVERAGED
OVER THE REGION BOUNDED BY 120W TO 170W AND WITHIN 5 DEGREES OF THE EQUATOR
(NINO 3.4 REGION) WILL MOST LIKELY REMAIN IN THE RANGE OF +0.5 TO +1.0 DEG C
FROM OND 2004 THROUGH MAM 2005. AFTER MAM 2005 THE OUTLOOK BECOMES MORE
UNCERTAIN... BUT MOST MODELS INDICATE A WEAKENING AND EVENTUAL END OF THE WARM
EPSIODE LATER IN 2005.
THE EXPECTED STRENGTH AND LOCATION OF THE ABNORMALLY WARM TROPICAL PACIFIC
SSTS DURING THE WINTER AND SPRING MONTHS ADD UNCERTAINTY TO THE FORECAST...
ALTHOUGH THE CONSENSUS OF MOST MODELS... BOTH STATISTICAL AND DYNAMICAL... IS
THAT THERE WILL BE A LARGE AREA OF ABOVE NORMAL SSTS NEAR AND EAST OF THE DATE
LINE... BUT THAT THERE WILL NOT BE SIGNIFICANTLY ABOVE NORMAL SSTS IN THE
EASTERN PART OF THE EQUATORIAL PACIFIC. IT SHOULD BE NOTED THAT THE PATTERN
AND MAGNITUDE OF THE SST ANOMALIES IN THE TROPICAL PACIFIC STRONGLY INFLUENCES
THE MIDDLE LATITUDE IMPACTS OF EL NINO... ESPECIALLY DURING THE COLD SEASON.
BASIN-WIDE... OR CLASSICAL STRONG EL NINOS LIKE THOSE OF 1982-83 AND 1997-98
HAVE A PATTERN OF ABNORMALLY WARM SSTS WHICH EXTEND ALL THE WAY FROM THE DATE
LINE TO THE COAST OF PERU. IMPACTS OF SUCH EL NINOS OFTEN INCLUDE ABNORMAL
WETNESS FROM CALIFORNIA TO FLORIDA ASSOCIATED WITH AN ACTIVE SUBTROPICAL JET
STREAM AND EASTWARD EXTENSION OF THE PACIFIC JET...RESPECTIVELY...AND ABNORMAL
DRYNESS CENTERED ON MONTANA AND THE OHIO VALLEY. THESE WARM EVENTS ARE ALSO
CHARACTERIZED BY ABNORMALLY WARM TEMPERATURES ACROSS THE NORTHERN TWO-THIRDS OF
THE CONTINENTAL U.S.
CENTRAL PACIFIC EL NINOS...LIKE THOSE IN 1963-64, 1968-69 AND 2002-03 ARE
CHARACTERIZED BY SMALL SST ANOMALIES IN THE EASTERN PACIFIC AND ABNORMALLY WARM
SSTS IN THE CENTRAL TROPICAL PACIFIC. THE U.S. TEMPERATURE RESPONSE TO THIS
TYPE OF EL NINO IS USUALLY COLDER THAN NORMAL OVER THE SOUTHEAST AND A MUCH
LESS RELIABLE HEAVY PRECIPITATION SIGNAL ACROSS THE SOUTHERN U.S. ..
ESPECIALLY IN CALIFORNIA.
THE TEMPERATURE OUTLOOK FOR NOVEMBER IS FOR AN INCREASED LIKELIHOOD OF BELOW
AVERAGE TEMPERATURES ACROSS MUCH OF THE SOUTH FROM THE SOUTH CENTRAL STATES
EASTWARD THROUGH THE SOUTHEAST AND ABOVE NORMAL TEMPERATURES IN ARIZONA - UTAH -
cALIFORNIA - NEVADA AND THE NORTHWEST.
THE PRECIPITATION FORECAST FOR NOVEMBER CALLS FOR AN ENHANCED LIKELIHOOD OF
BELOW-MEDIAN PRECIPITATION OVER THE NORTH CENTRAL PLAINS INCLUDING MINNESOTA...
WISCONSIN... IOWA... AND THE EASTERN PARTS OF NEBRASKA... SOUTH DAKOTA... AND
NORTH DAKOTA. ABOVE-MEDIAN PRECIPITATION IS FAVORED OVER MUCH OF THE SOUTHEAST
FROM EASTERN TEXAS THROUGH THE TENNESSEE VALLEY TO NORTHERN FLORIDA... GEORGIA...
AND NORTH AND SOUTH CAROLINA.
.
THE UPDATED FORECAST FOR NOVEMBER IS BASED PRIMARILY ON THE GUIDANCE FOR THE
FIRST TWO WEEKS OF THE MONTH FROM THE DYNAMIC MODELS COMBINED WITH INPUT FROM
THE SKILL-MASKED CFS AND SUPPORT FROM CCA AND OCN IN THE SOUTHWEST.
CURRENT OBSERVATIONS INDICATE THAT WEAK WARM EPISODE CONDITIONS (EL NINO)
CONTINUE OVER THE EQUATORIAL PACIFIC AND A MAJORITY OF SEA SURFACE TEMPERATURE
(SST) PREDICTION TOOLS INDICATE THAT AT LEAST WEAK EL NINO CONDITIONS WILL
CONTINUE FROM THIS FALL THROUGH THE FIRST FEW MONTHS OF 2005. THERE IS A CHANCE
THAT THE EL NINO COULD STRENGTHEN TO MODERATE INTENSITY AND A SMALLER CHANCE
THAT IT WILL WEAKEN BACK TO NEUTRAL STATUS. HOWEVER THE CONSENSUS AMONG
STATISTICAL AND DYNAMICAL MODEL PREDICTIONS CONTINUES TO INDICATE THAT
THREE-MONTH AVERAGED SST ANOMALIES IN THE CENTRAL EQUATORIAL PACIFIC AVERAGED
OVER THE REGION BOUNDED BY 120W TO 170W AND WITHIN 5 DEGREES OF THE EQUATOR
(NINO 3.4 REGION) WILL MOST LIKELY REMAIN IN THE RANGE OF +0.5 TO +1.0 DEG C
FROM OND 2004 THROUGH MAM 2005. AFTER MAM 2005 THE OUTLOOK BECOMES MORE
UNCERTAIN... BUT MOST MODELS INDICATE A WEAKENING AND EVENTUAL END OF THE WARM
EPSIODE LATER IN 2005.
THE EXPECTED STRENGTH AND LOCATION OF THE ABNORMALLY WARM TROPICAL PACIFIC
SSTS DURING THE WINTER AND SPRING MONTHS ADD UNCERTAINTY TO THE FORECAST...
ALTHOUGH THE CONSENSUS OF MOST MODELS... BOTH STATISTICAL AND DYNAMICAL... IS
THAT THERE WILL BE A LARGE AREA OF ABOVE NORMAL SSTS NEAR AND EAST OF THE DATE
LINE... BUT THAT THERE WILL NOT BE SIGNIFICANTLY ABOVE NORMAL SSTS IN THE
EASTERN PART OF THE EQUATORIAL PACIFIC. IT SHOULD BE NOTED THAT THE PATTERN
AND MAGNITUDE OF THE SST ANOMALIES IN THE TROPICAL PACIFIC STRONGLY INFLUENCES
THE MIDDLE LATITUDE IMPACTS OF EL NINO... ESPECIALLY DURING THE COLD SEASON.
BASIN-WIDE... OR CLASSICAL STRONG EL NINOS LIKE THOSE OF 1982-83 AND 1997-98
HAVE A PATTERN OF ABNORMALLY WARM SSTS WHICH EXTEND ALL THE WAY FROM THE DATE
LINE TO THE COAST OF PERU. IMPACTS OF SUCH EL NINOS OFTEN INCLUDE ABNORMAL
WETNESS FROM CALIFORNIA TO FLORIDA ASSOCIATED WITH AN ACTIVE SUBTROPICAL JET
STREAM AND EASTWARD EXTENSION OF THE PACIFIC JET...RESPECTIVELY...AND ABNORMAL
DRYNESS CENTERED ON MONTANA AND THE OHIO VALLEY. THESE WARM EVENTS ARE ALSO
CHARACTERIZED BY ABNORMALLY WARM TEMPERATURES ACROSS THE NORTHERN TWO-THIRDS OF
THE CONTINENTAL U.S.
CENTRAL PACIFIC EL NINOS...LIKE THOSE IN 1963-64, 1968-69 AND 2002-03 ARE
CHARACTERIZED BY SMALL SST ANOMALIES IN THE EASTERN PACIFIC AND ABNORMALLY WARM
SSTS IN THE CENTRAL TROPICAL PACIFIC. THE U.S. TEMPERATURE RESPONSE TO THIS
TYPE OF EL NINO IS USUALLY COLDER THAN NORMAL OVER THE SOUTHEAST AND A MUCH
LESS RELIABLE HEAVY PRECIPITATION SIGNAL ACROSS THE SOUTHERN U.S. ..
ESPECIALLY IN CALIFORNIA.
THE TEMPERATURE OUTLOOK FOR NOVEMBER IS FOR AN INCREASED LIKELIHOOD OF BELOW
AVERAGE TEMPERATURES ACROSS MUCH OF THE SOUTH FROM THE SOUTH CENTRAL STATES
EASTWARD THROUGH THE SOUTHEAST AND ABOVE NORMAL TEMPERATURES IN ARIZONA - UTAH -
cALIFORNIA - NEVADA AND THE NORTHWEST.
THE PRECIPITATION FORECAST FOR NOVEMBER CALLS FOR AN ENHANCED LIKELIHOOD OF
BELOW-MEDIAN PRECIPITATION OVER THE NORTH CENTRAL PLAINS INCLUDING MINNESOTA...
WISCONSIN... IOWA... AND THE EASTERN PARTS OF NEBRASKA... SOUTH DAKOTA... AND
NORTH DAKOTA. ABOVE-MEDIAN PRECIPITATION IS FAVORED OVER MUCH OF THE SOUTHEAST
FROM EASTERN TEXAS THROUGH THE TENNESSEE VALLEY TO NORTHERN FLORIDA... GEORGIA...
AND NORTH AND SOUTH CAROLINA.