90 Day Narrative

402 
FXUS05 KWBC 161331
PMD90D
PROGNOSTIC DISCUSSION FOR LONG-LEAD SEASONAL OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EST THU FEB 16 2017
SUMMARY OF THE OUTLOOK FOR NON-TECHNICAL USERS
RECENT OCEANIC AND ATMOSPHERIC OBSERVATIONS SHOW THAT ENSO-NEUTRAL CONDITIONS 
HAVE RETURNED TO THE EQUATORIAL PACIFIC OCEAN. THE OFFICIAL CPC ENSO FORECAST 
FAVORS ENSO-NEUTRAL CONDITIONS TO PERSIST AT LEAST THROUGHOUT BOREAL SPRING, 
WITH SIGNIFICANT UNCERTAINTY IN THE PHASE OF ENSO BEYOND THAT TIME.
THE MARCH-APRIL-MAY (MAM) 2017 TEMPERATURE OUTLOOK FAVORS ABOVE-NORMAL 
TEMPERATURES EAST OF A LINE THAT RUNS APPROXIMATELY FROM SOUTHERN CALIFORNIA 
THROUGH EASTERN WYOMING TO NORTHERN MINNESOTA, AND OVER WESTERN ALASKA. 
PROBABILITIES OF ABOVE-NORMAL TEMPERATURES EXCEED 50-PERCENT OVER PORTIONS OF 
THE SOUTHWESTERN AND SOUTH-CENTRAL CONUS, AND OVER MUCH OF THE NORTHEAST.  
THE MAM 2017 PRECIPITATION OUTLOOK INDICATES ENHANCED PROBABILITIES OF 
ABOVE-MEDIAN PRECIPITATION FROM MICHIGAN WESTWARD ACROSS THE NORTHERN TIER OF 
STATES TO THE PACIFIC NORTHWEST. BELOW-MEDIAN PRECIPITATION AMOUNTS ARE FAVORED 
OVER SOUTHWESTERN PORTIONS OF THE COUNTRY, AND ALONG MOST OF THE SOUTHERN COAST 
OF ALASKA.
EQUAL CHANCES (EC) ARE FORECAST OVER AREAS WHERE ODDS OF ABOVE-, BELOW-, OR 
NEAR-NORMAL SEASONAL MEAN TEMPERATURES AND SEASONAL ACCUMULATED PRECIPITATION 
AMOUNTS ARE EXPECTED TO BE SIMILAR TO CLIMATOLOGICAL PROBABILITIES.
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
OCEANIC AND ATMOSPHERIC OBSERVATIONS INDICATE THAT THE RECENT LA NINA THAT WAS 
IN PLACE ACROSS THE EQUATORIAL PACIFIC HAS GIVEN WAY TO ENSO-NEUTRAL 
CONDITIONS. THOUGH A RESIDUAL AREA OF RELATIVELY COOL WATER PERSISTS BETWEEN 
THE DATE LINE AND ABOUT 160W, SEA SURFACE TEMPERATURES (SSTS) FOR MOST AREAS 
EAST OF ABOUT 150W ARE NOW ABOVE-AVERAGE. ACCORDING TO THE LATEST ENSO 
DIAGNOSTIC DISCUSSION ISSUED BY CPC ON 9 FEBRUARY 2017, THE LATEST WEEKLY NINO 
INDEX VALUES WERE -0.3 DEG C IN THE WESTERNMOST NINO-4 AND NINO-3.4 REGIONS, 
AND +1.5 DEG C IN THE EASTERNMOST NINO 1+2 REGION. THE UPPER-OCEAN (TOP 300 
METERS) HEAT CONTENT ANOMALY INCREASED DURING JANUARY, AND FOR THE FIRST TIME 
IN NEARLY 11 MONTHS, BECAME SLIGHTLY POSITIVE. THIS REFLECTS THE INCREASE OF 
ABOVE-AVERAGE TEMPERATURES AT DEPTH. 
LOW-LEVEL (850-HPA) EASTERLY WINDS WERE SLIGHTLY ENHANCED OVER THE WESTERN 
TROPICAL PACIFIC, AND UPPER-LEVEL (200-HPA) WINDS WERE NEAR-AVERAGE. THE 
DOMINANT OUTGOING LONGWAVE RADIATION (OLR) ANOMALY PATTERN FOR THE PAST FEW 
MONTHS FEATURED ENHANCED CONVECTION ACROSS THE MARITIME CONTINENT REGION, AND 
SUPPRESSED CONVECTION OVER APPROXIMATELY THE CENTRAL THIRD OF THE TROPICAL 
PACIFIC. THIS DICHOTOMY IN ANOMALOUS CONVECTION BEARS THE SIGNATURE OF THE LA 
NINA THAT WAS RECENTLY IN PLACE. THIS PATTERN OF ANOMALOUS CONVECTION IS ALSO 
CONSISTENT WITH, AND REFLECTIVE OF, A POSITIVELY PHASED INDIAN OCEAN DIPOLE 
(IOD), WHICH HAS ALSO BEEN IN PLACE FOR SOME TIME. THESE SLOWLY VARYING, LOWER 
FREQUENCY SIGNALS (THE ENSO AND IOD) HAVE BEEN MODULATING INTRA-SEASONAL 
SIGNALS AS THEY PASS THROUGH THESE REGIONS. CONSTRUCTIVE INTERFERENCE WOULD 
RESULT WHEN THE ENHANCED CONVECTIVE PHASES OF THESE INTRA-SEASONAL SIGNALS 
MOVED ACROSS THE MARITIME CONTINENT REGION, AND DESTRUCTIVE INTERFERENCE WOULD 
RESULT WHEN THE ENHANCED CONVECTIVE PHASES OF THESE INTRA-SEASONAL SIGNALS 
MOVED ACROSS THE CENTRAL PACIFIC.
PROGNOSTIC DISCUSSION OF SST FORECASTS
THE CPC SST CONSOLIDATION FORECAST, WHICH INCLUDES THREE STATISTICAL FORECASTS 
ALONG WITH THE CFS, PREDICTS ENSO-NEUTRAL CONDITIONS WILL PERSIST FROM NOW 
UNTIL THE UPCOMING WINTER SEASON, AFTER WHICH A WEAK LA NINA WOULD BE BRIEFLY 
FAVORED. IN CONTRAST, THE CFS PREDICTS THE ONSET OF A WEAK EL NINO IN MAM 2017, 
WHICH STRENGTHENS TO MODERATE INTENSITY BY THE UPCOMING SUMMER. THE 
AMPLITUDE-CORRECTED NMME (NATIONAL MULTI-MODEL ENSEMBLE) PLUME OF NINO 3.4 SST 
FORECASTS IS GENERALLY IN-BETWEEN THE CFS AND THE CPC CONSOLIDATION FORECAST. 
THE CPC-IRI-CONSENSUS FORECAST DEPICTS DECREASING ODDS OF ENSO-NEUTRAL DURING 
THE NEXT FEW MONTHS, AND INCREASING ODDS OF A WARM EVENT. BY JJA AND JAS, THE 
PROBABILITY OF EITHER SCENARIO BECOMES AROUND 45 PERCENT EACH, WITH ONLY 10 
PERCENT REMAINING FOR A COLD EVENT. THOUGH THERE IS A REASONABLE CHANCE OF AN 
EL NINO OCCURRING DURING THE NEXT COLD SEASON, IT IS TOO EARLY, AND TOO 
UNCERTAIN AT THIS TIME, TO CONSIDER USING THIS INFORMATION IN THE SEASONAL 
TEMPERATURE AND PRECIPITATION OUTLOOKS.
PROGNOSTIC TOOLS USED FOR U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS
THE OUTLOOKS FOR MAM 2017 THROUGH JAS 2017 ARE BASED ON DYNAMICAL MODEL OUTPUTS 
FROM THE NMME AND ITS CONSTITUENT INPUTS, BALANCED WITH INPUT FROM THE CPC 
CONSOLIDATION AND CONSTRUCTED ANALOG BASED ON SSTS (CA-SST).  BEYOND JAS 2017, 
THE OUTLOOKS ARE BASED ON HISTORICAL TRENDS, THE CPC CONSOLIDATION, AND CA-SST.
PROGNOSTIC DISCUSSION OF OUTLOOKS - MAM 2017 TO MAM 2018
TEMPERATURE
THE OUTLOOK FOR MAM 2017 WAS CHANGED LITTLE FROM LAST MONTH. PROBABILITIES FOR 
ABOVE-NORMAL TEMPERATURES WERE EXPANDED WESTWARD ACROSS THE GREAT LAKES REGION 
AND UPPER MISSISSIPPI VALLEY, BASED ON THE NMME AND MANY OF ITS COMPONENT 
INPUTS (SUCH AS THE CANADIAN CANCM3 AND CANCM4 MODELS, GFDL FLOR, CFS, NCAR, 
AND NASA). PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES WERE ALSO INCREASED TO 
50-PERCENT IN NEW ENGLAND, BASED ON MANY OF THESE SAME DYNAMICAL MODELS. 
PROBABILITIES FOR RELATIVE WARMTH WERE ALSO INCREASED ACROSS MUCH OF THE EAST, 
FROM BETWEEN 33-40 PERCENT, TO BETWEEN 40-50 PERCENT. THE FAVORED ABOVE-NORMAL 
TEMPERATURES IN WESTERN ALASKA (ESPECIALLY THE ALEUTIANS) FOR THE MAM SEASON 
ARE BASED PRIMARILY ON DYNAMICAL MODEL INPUTS. ONE REGION THAT WAS ORIGINALLY 
CONSIDERED FOR A FORECAST OF BELOW-NORMAL TEMPERATURES WAS THE NORTH-CENTRAL 
CONUS, WHERE A ENSO-TREND BASED FORECAST TOOL THAT USES THE CPC SST 
CONSOLIDATION AS A PREDICTOR INDICATED THIS POTENTIAL. HOWEVER, WITH THE RECENT 
TRANSITION OF LA NINA TO ENSO-NEUTRAL CONDITIONS, AS WELL AS LITTLE DYNAMICAL 
MODEL SUPPORT, IT WAS DECIDED NOT TO INCLUDE THIS AREA OF BELOW-NORMAL 
TEMPERATURES ON THE MAP.
FROM AMJ THROUGH JAS 2017, ONLY MINOR ADJUSTMENTS WERE MADE TO THE PREVIOUS 
OUTLOOKS, BASED PRIMARILY ON DYNAMICAL AND STATISTICAL MODEL GUIDANCE. ACROSS 
THE WESTERN CONUS, PROBABILITIES FAVORING ABOVE-NORMAL (UPPER-TERCILE) 
TEMPERATURE ANOMALIES EXPANDED GENERALLY TOWARDS THE NORTHWEST. THE 
PROBABILITIES IN EXCESS OF 50-PERCENT ACROSS THE SOUTHWEST ARE CONSISTENT WITH 
SPRINGTIME TEMPERATURE TRENDS. BY MJJ, THE PREDICTED AREA OF EC IS CONFINED TO 
THE NORTH-CENTRAL CONUS, AND A NOTICEABLE WEAKNESS IN THE PROBABILITIES FOR 
ABOVE-NORMAL TEMPERATURES TAKES SHAPE FROM THE MIDWESTERN STATES TOWARDS THE 
CAROLINAS. THIS IS A FEATURE THAT IS PREDICTED BY MANY OF THE DYNAMICAL AND 
STATISTICAL MODELS, AND THIS SUGGESTS THE POTENTIAL FOR COLDER AIR MASSES TO 
MOVE THROUGH THIS CORRIDOR. ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR ALL OF 
ALASKA BY MJJ. IN JJA, THE PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES EXCEEDS 
50-PERCENT ACROSS NEW ENGLAND, BASED ON SUCH MODELS AS THE CFS, CALIBRATED NMME 
AND IRI. BY JAS, THE CORRIDOR OF RELATIVE WEAKNESS NOTED EARLIER (WHICH ALSO 
CONTAINED SOME EC) FILLS IN COMPLETELY WITH MODEST PROBABILITIES FOR 
UPPER-TERCILE WARMTH. FROM ASO ONWARD, THE CPC CONSOLIDATION TOOL (WHICH 
INCORPORATES HISTORICAL TRENDS) AND THE SST-CA TOOL WERE USED. THE GENERAL 
SHAPE OF THE PREDICTED PATTERN FAVORING RELATIVE WARMTH CONTINUES ACROSS THE 
CONUS AND ALASKA, THOUGH WITH DIMINISHED PROBABILITIES. DURING THE SON AND OND 
SEASONS, PROBABILITIES FOR UPPER-TERCILE TEMPERATURE ANOMALIES INCREASE TO OVER 
60-PERCENT FOR THE NORTH SLOPE OF ALASKA. THIS IS PRIMARILY ATTRIBUTED TO THE 
DELAYED ONSET, AND REDUCED COVERAGE OF, SEA ICE FORMATION IN RECENT YEARS. BY 
FMA AND MAM 2018, THE FAVORED ABOVE-NORMAL TEMPERATURES OVER THE EASTERN CONUS 
GRADUALLY GIVE WAY TO EC, WHILE THE WARM SIGNAL TREND PERSISTS OVER THE WESTERN 
CONUS AND ALASKA.
PRECIPITATION
THE MAM 2017 PRECIPITATION OUTLOOK DEPICTS A FEW DIFFERENCES WITH THE PREVIOUS 
OUTLOOK. BASED PRIMARILY ON THE DYNAMICAL MODEL SUITE, THE FAVORED AREA OF 
ABOVE-MEDIAN PRECIPITATION WAS EXPANDED WESTWARD ACROSS THE NORTHERN ROCKIES 
AND THE PACIFIC NORTHWEST. THE AREA OF FAVORED BELOW-MEDIAN PRECIPITATION OVER 
THE SOUTHEAST WAS REMOVED DUE TO THE LARGE DIFFERENCES (AND HENCE LARGE 
UNCERTAINTIES) BETWEEN THE VARIOUS MODELS. THE AREA OF PREDICTED BELOW-MEDIAN 
(OR LOWER-TERCILE) PRECIPITATION ACROSS THE SOUTHWEST WAS INCREASED IN SIZE, 
WHILE A SLIVER OF LOWER-TERCILE PRECIPITATION WAS ADDED TO THE SOUTHERN COAST 
OF ALASKA. THIS LATTER FEATURE IS OFTEN OBSERVED DURING LA NINA WINTERS, AND IS 
SUPPORTED BY THE NMME, THE CANADIAN CANCM3 MODEL, GFDLS FLOR AND CM2.1 MODELS, 
AND NCARS CCSM4 AND CESM MODELS. THE CFS AND INTERNATIONAL MULTI-MODEL ENSEMBLE 
(IMME), HOWEVER, DID NOT PREDICT THIS FEATURE.
DURING AMJ AND MJJ 2017, THE ONLY SIGNAL CONSIDERED RELIABLE WAS AN AREA OF 
ABOVE-MEDIAN PRECIPITATION ACROSS THE NORTHWESTERN PORTION OF THE LOWER 48 
STATES. THE NMME AND CFS ALSO PREDICTED EXTENSIONS OF THIS WET AREA INTO THE 
SOUTHWEST, BUT THESE WERE DEEMED UNRELIABLE. BY JJA AND JAS, AN AREA OF 
BELOW-MEDIAN PRECIPITATION IS FAVORED ACROSS THE NORTHWEST, WHICH IS A FAIRLY 
RELIABLE TREND SIGNAL, AS IS THE FAVORED WET SIGNAL OVER THE NORTHEAST. THE 
LATTER SIGNAL CONTINUES THROUGH ASO. FOR SON AND OND, THERE ARE NO RELIABLE 
PRECIPITATION SIGNALS, HENCE THE NATIONAL FORECAST OF EC. FROM NDJ 2017 THROUGH 
MAM 2018, THE PRECIPITATION OUTLOOKS ARE PRIMARILY BASED ON HISTORICAL TRENDS, 
BUT ALSO ON THE SST-CA TOOL. LOWER-TERCILE PRECIPITATION IS FAVORED FOR PARTS 
OF THE WEST COAST AND GULF COAST IN BOTH NDJ AND DJF. THIS SIGNAL OF RELATIVE 
DRYNESS CONTINUES ACROSS THE EASTERN GULF COAST REGION AND EXPANDS ACROSS THE 
CAROLINAS OUT TO MAM 2018, WHILE A DRY SIGNAL EMERGES OVER THE DESERT SOUTHWEST 
DURING THE FMA AND MAM 2018 SEASONS.
FORECASTER: ANTHONY ARTUSA
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/LONG_RANGE/TOOLS.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/PRODUCTS/SOILMST_MONITORING/US/OUTLOOK/OUTLOOK.SHTM
L
(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 MAR 16 2017
1981-2010 BASE PERIOD MEANS WERE IMPLEMENTED EFFECTIVE WITH THE MAY 19, 2011 
FORECAST RELEASE.
$$