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FXUS05 KWBC 181331
PMD90D
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830AM EST THURSDAY DEC 18 2014

SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS

CURRENT ATMOSPHERIC AND OCEANIC OBSERVATIONS SHOW MIXED SIGNALS REGARDING THE
ENSO STATE. SOME OBSERVATIONS, SUCH AS THE SEA SURFACE TEMPERATURES (SSTS)
ALONG THE EQUATOR IN THE CENTRAL PACIFIC OCEAN ARE SUGGESTIVE OF EL NINO
CONDITIONS, WHILE MANY OF THE ATMOSPHERIC CONDITIONS ASSOCIATED WITH EL NINO
ARE ABSENT. MOST NOTABLY, THERE HAS NOT BEEN ANY ANOMALOUS CONVECTION OBSERVED
IN THE CENTRAL EQUATORIAL PACIFIC.  TAKEN IN COMBINATION, THE OBSERVATIONS
CONTINUE TO SUGGEST ENSO-NEUTRAL CONDITIONS, THOUGH BIASED TOWARD A WARM ENSO
STATE. BOTH STATISTICAL AND DYNAMICAL MODELS CONSISTENTLY FAVOR THE DEVELOPMENT
OF WEAK EL NINO CONDITIONS. THE CHANCE OF EL NINO DEVELOPMENT IS ONLY ABOUT
60%, WITH A 40% CHANCE FOR A CONTINUATION OF ENSO-NEUTRAL CONDITIONS THROUGH
THE WINTER.



THE TEMPERATURE OUTLOOK FOR JANUARY-FEBRUARY-MARCH (JFM) 2015 INDICATES
ELEVATED CHANCES OF ABOVE-NORMAL MEAN TEMPERATURES FOR ALASKA, THE WESTERN
CONUS, AND IN PARTS OF NEW ENGLAND. THE CHANCES OF BELOW-NORMAL MEAN
TEMPERATURES ARE ELEVATED ACROSS THE SOUTHEASTERN THIRD OF THE U.S..



THE JFM 2015 PRECIPITATION OUTLOOK INDICATES ENHANCED CHANCES OF BELOW-MEDIAN
PRECIPITATION FOR PARTS OF THE PACIFIC NORTHWEST, NORTHERN ROCKIES, GREAT LAKES
AND OHIO VALLEY. INCREASED PROBABILITIES FOR ABOVE-MEDIAN PRECIPITATION AMOUNTS
ARE FORECAST FROM CALIFORNIA EASTWARD TO THE SOUTHERN PLAINS, AND AGAIN ACROSS
THE SOUTHEAST COAST. THE PROBABILITIES FOR ABOVE-MEDIAN PRECIPITATION ARE ALSO
ENHANCED OVER PARTS OF COASTAL SOUTHERN ALASKA.



IN AREAS WHERE THE LIKELIHOODS OF SEASONAL MEAN TEMPERATURES AND SEASONAL
ACCUMULATED PRECIPITATION AMOUNTS ARE SIMILAR TO CLIMATOLOGICAL PROBABILITIES,
EQUAL CHANCES (EC) IS INDICATED.

BASIS AND SUMMARY OF THE CURRENT LONG-LEAD OUTLOOKS
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

ATMOSPHERIC AND OCEANIC CONDITIONS IN THE TROPICAL PACIFIC REMAIN MOST
CONSISTENT WITH AN ENSO-NEUTRAL STATE. SST ANOMALIES REMAIN ABOVE +0.5 IN ALL
THE ENSO CRITICAL REGIONS OF THE PACIFIC. SSTS ALONG THE EQUATOR ARE ABOVE +0.5
C EVERYWHERE FROM ABOUT 150 E TO JUST SHY OF THE SOUTH AMERICAN COAST, WITH
SOME REGIONAL ANOMALIES IN EXCESS OF +1.0 C. OCEAN SUBSURFACE TEMPERATURE
ANOMALIES REMAINED FAIRLY STEADY IN THE PAST MONTH, AND RANGE FROM +1.0 TO +4.0
C AT BETWEEN 50 AND 150 METERS DEPTH, EXCEPT NEAR SOUTH AMERICA WHERE ABOVE
NORMAL OCEAN TEMPERATURES ARE CONFINED TO THE UPPER 50 METERS OR SO.



THE USUAL ATMOSPHERIC RESPONSE TO EL NINO ARE NOTABLY ABSENT FROM RECENT
OBSERVATIONS. RECENT OLR ANOMALIES SUGGEST THAT CONVECTION IS NEAR TO BELOW
NORMAL OVER THE CENTRAL EQUATORIAL PACIFIC IN AREAS THAT USUALLY SEE
ABOVE-NORMAL CONVECTION DURING EL NINOS. BOTH LOWER AND UPPER LEVEL WIND
ANOMALIES DURING THIS PERIOD ARE ONLY WEAKLY CONSISTENT WITH EL NINO. WITHOUT
LARGE SCALE ATMOSPHERIC ANOMALIES NORMALLY ASSOCIATED WITH EL NINO PRESENT,
ENSO-NEUTRAL STILL BEST DESCRIBES THE CURRENT CONDITIONS IN THE PACIFIC.



SIGNIFICANT EXTRA-TROPICAL ANOMALIES THAT MAY HAVE AN IMPACT ON THE CLIMATE
OVER NORTH AMERICA INCLUDE A DISTINCT POSITIVE PDO SIGNAL, WITH ABOVE-NORMAL
SSTS FORMING A HORSESHOE FROM THE SUBTROPICS TO THE WEST COAST OF NORTH
AMERICA, AND EXTENDING WESTWARD ACROSS THE FAR NORTHERN PACIFIC.

PROGNOSTIC DISCUSSION OF SST FORECASTS

THERE IS FAIRLY GOOD CONSENSUS AMONG BOTH STATISTICAL AND DYNAMICAL MODELS FOR
ABOVE-NORMAL SSTS TO PERSIST IN THE NINO 3.4 REGION THROUGH THE BOREAL WINTER.
MOST OF THE TROPICAL ATMOSPHERIC RESPONSE TO EL NINO IS USUALLY WELL
ESTABLISHED BY THIS LATE IN THE YEAR, SO IN SPITE OF THE CONSENSUS OF
PREDICTIONS, THE EL NINO IS EXPECTED TO BE WEAK, IF IT DEVELOPS AT ALL.  THE
CURRENT CONSENSUS OF OPINION AMONG FORECASTERS AT CPC AND IRI IS FOR A 60%
CHANCE OF EL NINO DEVELOPMENT.  THE MULTI-MODEL AVERAGE OF NINO 3.4 SSTS IS FOR
ANOMALIES OF CLOSE TO +1.0 C LASTING INTO SUMMER 2015. IN FACT, THE LATEST
DYNAMICAL MODELS SUGGEST A BETTER THAN NORMAL CHANCE AT A PROLONGED PERIOD OF
ABOVE-NORMAL SSTS IN THE EQUATORIAL PACIFIC, PERHAPS LASTING THROUGH MOST OF
2015. HOWEVER, A CALIBRATED CONSENSUS OF BOTH STATISTICAL MODELS AND THE CFSV2
PREDICTIONS SUGGESTS AN EARLIER PEAK TO NINO 3.4 SSTS OF JUST OVER +0.7 C, IN
NDJ 2014-15, DECREASING SLOWLY AFTERWARD AND REACHING +0.5 C BY JFM 2015 AND
CONTINUING A SLOW DECREASE THROUGHOUT THE YEAR.



MOST MODELS RUN AS PART OF THE NMME AND IMME PERSIST ABOVE-NORMAL SSTS ALONG
THE WEST COAST OF NORTH AMERICA THROUGH AT LEAST LATE SPRING 2015. THE AREAL
EXTENT AND MAGNITUDE OF THESE PREDICTED ANOMALIES PROJECT ONTO A POSITIVE PDO
PATTERN AND ARE LARGE ENOUGH TO POTENTIALLY HAVE AN IMPACT ON CLIMATIC
CONDITIONS OVER NORTH AMERICA IN THE NEXT SEVERAL SEASONS, IN AS MUCH AS THEY
ARE FORCED BY A PERSISTENT ATMOSPHERIC STATE OVER THE NORTH PACIFIC.

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

THE TEMPERATURE AND PRECIPITATION OUTLOOKS FROM JFM THROUGH MAM 2015 ARE
INFLUENCED PARTLY BY THE POTENTIAL IMPACTS OF A WEAK EL NINO. THE LIKELY
MARGINAL STRENGTH OF EL NINO RESULTS IN ONLY SLIGHTLY ENHANCED CHANCES OF
CLIMATIC ANOMALIES IN THE REGIONS USUALLY INFLUENCED BY ENSO, AND IS WELL SHORT
OF THE CONFIDENCE ASSOCIATED WITH EVEN A MODERATE EVENT. LARGE-SCALE
INDICATORS, SUCH AS THE POSITIVE PDO, CURRENTLY ARE CONSISTENT WITH EL NINO
CONDITIONS AND MAY INDICATE THE EVENTUAL ESTABLISHMENT OF THE USUAL
TELECONNECTION PATTERNS ASSOCIATED WITH EL NINO IN SPITE OF THE CURRENTLY
DISORGANIZED EQUATORIAL ATMOSPHERIC STATE. THAT SAID, THE OVERWHELMING SIGNAL
FROM THE DYNAMICAL AND STATISTICAL MODELS IS THAT THE CONVECTIVE MAXIMUM IN THE
EQUATORIAL PACIFIC IS LIKELY WEST OF THE DATE LINE, CASTING DOUBT ON THE
DEVELOPMENT OF ANY ROBUST ENSO TELECONNECTIONS.



THE CONSTRUCTED ANALOG FORECAST FOR TEMPERATURE AND PRECIPITATION BASED ON
GLOBAL SST PATTERNS (CA-SST) WAS ALSO UTILIZED IN THE OUTLOOKS AS WAS
INFORMATION FROM A LARGE VARIETY OF DYNAMICAL MODEL GUIDANCE, INCLUDING THE
CFS, THE NMME AND IMME. OTHER GUIDANCE FROM INTERNATIONAL CENTERS WAS UTILIZED
AS WELL.



FOR OUTLOOKS FROM AMJ THROUGH JFM 2016, DECADAL TRENDS DUE TO CHANGES IN THE
CLIMATE BASE STATE ARE WEIGHTED MORE HEAVILY, THOUGH DYNAMICAL AND STATISTICAL
GUIDANCE IS ALSO APPLIED WHERE APPROPRIATE.

PROGNOSTIC DISCUSSION OF OUTLOOKS - JFM 2015 TO JFM 2016

TEMPERATURE

THE OUTLOOK FOR JFM 2015 INDICATES ELEVATED CHANCES FOR ABOVE-NORMAL
TEMPERATURES IN ALASKA, MOST OF THE WESTERN CONUS, AND FOR PARTS OF NEW
ENGLAND. THERE IS NOTABLY HIGH SPREAD AMONG TOOLS FOR TEMPERATURES IN THE
CENTRAL AND EASTERN CONUS, WITH SOME TOOLS AND DYNAMICAL MODELS FAVORING BELOW
NORMAL TEMPERATURES, WHILE OTHERS FAVOR ABOVE. THIS MAY, IN PART BE RELATED TO
THE DIFFERING STRENGTHS OF THE EL NINO PREDICTIONS FROM THE MODELS. STRONGER EL
NINO EVENTS TEND TO BE ASSOCIATED WITH ABOVE-NORMAL TEMPERATURES IN THE UPPER
MID-WEST AND GREAT LAKES, WHILE WEAK EVENTS SHOW COOLER AND MORE VARIABLE
TEMPERATURE CONDITIONS. GIVEN THE EXPECTED WEAK NATURE OF THIS EL NINO, THE
WARMER SOLUTIONS AMONG THE TOOLS WERE LARGELY DISCOUNTED. STATISTICAL SIGNALS
FROM BOTH THE CA-SST AND THE OCTOBER EURASIAN SNOWCOVER STILL FAVOR A -AO/NAO
PATTERN FOR THE UPCOMING THREE MONTH SEASON. THIS INTRODUCES UNCERTAINTY ACROSS
THE NORTH-CENTRAL CONUS, WHERE NMME PROBABILITIES INDICATE ELEVATED ODDS OF
ABOVE-NORMAL TEMPERATURES. SOME OTHER NUMERICAL GUIDANCE, INCLUDING THE ECMWF
AND UKMET, FAVOR BELOW-NORMAL TEMPERATURES ACROSS THE REGION. COMBINING THIS
VARIOUS GUIDANCE WITH THE STATISTICAL TOOLS SUGGESTS THAT EC IS THE MOST
APPROPRIATE FORECAST FOR PARTS OF THE NORTH-CENTRAL CONUS. ALSO ADDING TO THE
UNCERTAINTY IS THE FACT THAT NEARLY ALL OF THE NUMERICAL GUIDANCE PLACES THE
ANOMALOUS CONVECTION WEST OF THE DATE LINE IN THE EQUATORIAL PACIFIC.
TELECONNECTIONS BASED ON ENHANCED CONVECTION IS THIS REGION ARE WEAK, BUT FAVOR
ANOMALOUS RIDGING OVER ALASKA AND A TEMPERATURE SOLUTION MORE IN LINE WITH THE
ECMWF AND UKMET SOLUTIONS. ALONG THE WEST COAST AND ALASKA, ALL TOOLS ARE IN
REMARKABLE AGREEMENT, AND SO SOME AREAS EXCEEDING 60% PROBABILITY OF
ABOVE-NORMAL TEMPERATURES ARE INDICATED. OVER THE SOUTHEASTERN CONUS, THERE IS
REASONABLE AGREEMENT AMONG THE TOOLS FAVORING NEAR- TO BELOW-NORMAL
TEMPERATURES. THERE IS SOME UNCERTAINTY, HOWEVER, IN THAT THE DYNAMICAL TOOLS
THAT INDICATE COOLER SOLUTIONS ACROSS THE CENTRAL AND NORTHERN CONUS ARE
LIKEWISE LESS COLD ACROSS THE FAR SOUTHEASTERN CONUS. THE COMBINATION OF +ENSO,
A TILT TOWARD -AO/NAO, AND +PDO, LEAD TO A LARGE AREA FAVORING BELOW-NORMAL
TEMPERATURES. HOWEVER, SINCE CONFIDENCE IN THOSE FIRST TWO INDICATORS IS LOW,
PROBABILITIES REMAIN VERY MODEST.



IT IS IMPORTANT TO NOTE THAT THE USE OF THE +PDO IN THIS CASE IS NOT SO MUCH
BECAUSE WE EXPECT THE PATTERN OF SST ANOMALIES TO FORCE AN ATMOSPHERIC
RESPONSE, BECAUSE THIS IS QUITE DEBATABLE. RATHER, DUE TO EXCEPTIONAL DYNAMICAL
MODEL AGREEMENT, IT IS ASSUMED THAT THE ATMOSPHERIC CIRCULATION (+PNA) OVER THE
NORTH PACIFIC IS CONSISTENT FROM MODEL TO MODEL, AND THUS CAN BE HARVESTED FOR
PREDICTION. EVEN THIS ASSUMPTION IS NOT PARTICULARLY STRONG, THOUGH, SINCE IT
HAS BEEN SHOWN RECENTLY THAT THE CFS HAS LITTLE SHILL IS PREDICTING PDO CHANGES
ON MONTHLY TIMESCALES.



THE PATTERN OF FORECAST TEMPERATURE PROBABILITIES FAVORED IN JFM 2015 EXTEND
INTO FMA 2015 AND THEN DIMINISHES THEREAFTER. PREDICTED ANOMALIES FOR AMJ 2015
AND BEYOND ARE LARGELY DETERMINED BY RECENT TRENDS, THE CA-SST, DYNAMICAL
GUIDANCE WHERE AVAILABLE, AND CONTEMPORANEOUS +PDO REGRESSIONS. SIGNALS FROM
TRENDS AND THE CA-SST DOMINATE DURING THE SUMMER AND FALL MONTHS, RESULTING IN
ELEVATED CHANCES FOR ABOVE-NORMAL TEMPERATURES FOR MUCH OF ALASKA, AND AS WELL
AS MUCH OF THE CONUS EXCEPT FOR INTERIOR PORTIONS.



BY NEXT WINTER, THE CON IS USED HEAVILY, WHICH EMPHASIZES TRENDS, ALONG WITH
THE CA-SST. SOME THOUGHT WAS PUT INTO WHAT ENSO STATE IS MOST FAVORED FOR NEXT
WINTER, AS CAN BE APPROPRIATE WHEN THERE IS A ROBUST ENSO ONGOING. FOR EXAMPLE,
IF WE ARE CURRENTLY IN A MODERATE TO STRONG EL NINO, AN EL NINO THE FOLLOWING
WINTER IS LESS LIKELY. HOWEVER, THERE ARE NOTABLE DISAGREEMENTS BETWEEN THE
DYNAMICAL AND STATISTICAL TOOLS THROUGHOUT 2015 WHICH, COMBINED WITH OUR
CURRENT WEAK/NEUTRAL ENSO STATE, YIELDS LITTLE SIGNAL FOR NEXT WINTER.



SUBSTANTIALLY ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES ARE FORECAST
FOR NORTHERN ALASKA FROM ASO 2015 THROUGH OND 2015 DUE TO THE LIKELY ANOMALOUS
DELAY IN ARCTIC OCEAN AND BERING SEA SEA-ICE COVER FOR OCTOBER AND NOVEMBER IN
THE LAST DECADE RELATIVE TO 1981-2010.

PRECIPITATION

THE ELEVATED CHANCES FOR A WEAK EL NINO EVENT INFLUENCES THE PRECIPITATION
OUTLOOK MAPS THROUGH FMA 2015. DYNAMICAL MODEL FORECAST GUIDANCE FROM THE NMME
AND IMME AND THEIR PARTICIPANT MODELS GENERALLY SUPPORT WARM EVENT COMPOSITES.
PRECIPITATION FORECASTS FROM THE GLOBAL SST BASED CONSTRUCTED ANALOG TOOL WAS
ALSO CONSIDERED.



THE CHANCES FOR ABOVE-MEDIAN PRECIPITATION AMOUNTS ARE ELEVATED FOR CALIFORNIA,
ACROSS THE SOUTHWEST, PARTS OF THE SOUTHERN GREAT BASIN, THE SOUTHERN PLAINS
AND THE SOUTHEAST CONUS FROM JFM THROUGH FMA 2015. ENHANCED PROBABILITIES FOR
BELOW-MEDIAN PRECIPITATION ARE INDICATED FOR THE PACIFIC NORTHWEST THROUGH FMA
2015, AND FROM THE CENTRAL MISSISSIPPI VALLEY INTO THE GREAT LAKES REGION FROM
JFM THROUGH MAM 2015. PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION ARE ENHANCED
FOR PARTS OF SOUTHERN ALASKA THROUGH FMA 2015.



ODDS OF ABOVE-MEDIAN PRECIPITATION ARE ENHANCED DURING AMJ AND MJJ 2015 FOR
PARTS OF THE PACIFIC NORTHWEST AND CENTRAL ROCKIES BASED ON NMME, CA-SST, AND
PDO REGRESSIONS. THE MODEL GUIDANCE FROM NMME HAS HIGH PROBABILITIES OF
ABOVE-MEDIAN PRECIPITATION ACROSS PARTS OF THE SOUTHWEST DURING THIS PERIOD,
WHICH CONTRADICTS GUIDANCE FROM THE CON BASED LARGELY ON TRENDS AS WELL AS THE
CA-SST. THEREFORE, EC REMAINS FOR THE SOUTHWEST DURING THESE LEADS FOR THE TIME
BEING, THOUGH THIS WILL BE MONITORED CLOSELY OVER THE NEXT COUPLE OF MONTHS.



TRENDS IN PARTS OF THE SOUTHEAST CONUS INDICATE ELEVATED CHANCES FOR
BELOW-MEDIAN PRECIPITATION AMOUNTS IN DJF 2015-16.

FORECASTER: STEPHEN BAXTER

THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1981 AND 2010, FOLLOWING
THE WORLD METEROLOGICAL ORGANIZATION CONVENTION OF USING THE MOST RECENT 3
COMPLETE DECADES AS THE CLIMATIC 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.

FOR A DESCRIPTION OF OF THE STANDARD FORECAST TOOLS - THEIR SKILL- AND THE
FORECAST FORMAT PLEASE SEE OUR WEB PAGE AT
HTTP:/WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/90DAY/DISC.HTML
(USE LOWER CASE LETTERS)
INFORMATION ON THE FORMATION OF SKILL OF THE CAS FORECASTS MAY BE FOUND AT:
HTTP://WWW.CPC.NCEP.NOAA.GOV/SOILMST/FORECASTS.HTML (USE LOWERCASE LETTERS)
NOTES - THESE CLIMATE OUTLOOKS ARE INTENDED FOR USE PRIOR TO THE START OF THEIR
VALID PERIOD.  WITHIN ANY GIVEN VALID PERIOD OBSERVATIONS AND SHORT AND MEDIUM
RANGE FORECASTS SHOULD BE CONSULTED.

THIS SET OF OUTLOOKS WILL BE SUPERSEDED BY THE ISSUANCE OF THE NEW SET NEXT
MONTH ON JAN 15 2015


1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011
FORECAST RELEASE.
$$



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