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Official 90-day Outlooks are issued once each month near mid-month at 8:30am Eastern Time. Please consult the schedule of 30 & 90-day outlooks for exact release dates.

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    0.5mn AMJ 2017
    1.5mn MJJ 2017
    2.5mn JJA 2017
    3.5mn JAS 2017
    4.5mn ASO 2017
    5.5mn SON 2017
    6.5mn OND 2017
    7.5mn NDJ 2017
    8.5mn DJF 2017
    9.5mn JFM 2018
   10.5mn FMA 2018
   11.5mn MAM 2018
   12.5mn AMJ 2018
    0.5mn Apr 2017


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HOME> Outlook Maps>Seasonal Forecast Discussion
 
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT FRI MAR 31 2017

30-DAY OUTLOOK DISCUSSION FOR APRIL 2017

THE UPDATE TO THE APRIL TEMPERATURE AND PRECIPITATION OUTLOOKS IS MADE USING
THE LATEST GUIDANCE FOR THE MONTH FROM THE CFS, AS WELL AS DYNAMICAL MODEL
GUIDANCE FOR WEEK 2, AND WEEKS 3 AND 4, AND TEMPERATURE AND PRECIPITATION
FORECASTS FOR WEEK 1 FROM NUMERICAL WEATHER PREDICTION MODELS. OVERALL, ENSO
NEUTRAL CONDITIONS CONTINUE FOR THE TROPICAL PACIFIC, AND THE MJO REMAINS
INACTIVE, AS INDICATED BY THE WHEELER AND HENDON RMM INDICES. DYNAMICAL MODELS
GENERALLY INDICATE THAT MJO WILL REMAIN INACTIVE THROUGH MUCH OF APRIL.
THEREFORE THE UPDATE RELIES PRIMARILY ON DYNAMICAL MODEL GUIDANCE.

THE UPDATED TEMPERATURE OUTLOOK FOR APRIL IS VERY SIMILAR TO THE PREVIOUSLY
RELEASED HALF MONTH LEAD OUTLOOK, WITH PROBABILITIES OF ABOVE NORMAL
TEMPERATURES INCREASED OVER THE SOUTHWEST INCLUDING SOUTHERN CALIFORNIA, AS
WELL AS INCREASED PROBABILITIES ACROSS THE SOUTHEAST, AND FOR SOUTHERN ALASKA.
THIS UPDATE FOLLOWS THE LATEST GUIDANCE FROM THE CFS MONTHLY FORECAST. ENHANCED
PROBABILITIES OF ABOVE NORMAL TEMPERATURES CONTINUE FOR MUCH OF THE EASTERN
CONUS.

THE UPDATED PRECIPITATION OUTLOOK FOR APRIL HAS LARGELY CHANGED BASED ON RECENT
NUMERICAL WEATHER PREDICTION FOR THE FIRST WEEK IN APRIL, AS WELL AS
CONSIDERATION OF THE RECENT CFS MONTHLY FORECASTS, AND FORECASTS FOR WEEK 2
FROM THE ECMWF AND GEFS MODELS, AND FOR WEEKS 3 AND 4 FROM THE ECMWF MODEL.
THE PRECIPITATION FORECAST NOW INDICATES AN INCREASED CHANCE OF ABOVE MEDIAN
PRECIPITATION FOR COASTAL REGIONS OF NORTHERN CALIFORNIA, OREGON, AND
WASHINGTON STATE, WHERE MODEL FORECASTS NOW INDICATE INCREASED PRECIPITATION
FOR THE MONTH. WHILE THE AREA OF ABOVE MEDIAN PRECIPITATION OVER PARTS OF
EASTERN TEXAS, THE LOWER MISSISSIPPI VALLEY, AND CENTRAL GULF COAST IN THE
UPDATED FORECAST IS SIMILAR TO THE HALF MONTH LEAD FORECAST, FORECASTS FOR WEEK
2, AS WELL AS WEEKS 3 AND 4 COMBINED, NOW INDICATE INCREASED PROBABILITIES OF
BELOW MEDIAN PRECIPITATION. HOWEVER, FORECASTS FOR THE FIRST WEEK OF THE MONTH
OF APRIL INDICATE A HIGH LIKELIHOOD OF SIGNIFICANT PRECIPITATION, SUCH THAT THE
PROBABILITIES OF ABOVE MEDIAN PRECIPITATION ARE ENHANCED FOR THE FULL MONTH OF
APRIL.

THE FORECAST MESSAGE FOR THE HALF MONTH LEAD APRIL TEMPERATURE AND
PRECIPITATION OUTLOOKS ISSUED ON MARCH 16 IS BELOW.
_____

OCEANIC AND MOST ATMOSPHERIC SIGNALS ASSOCIATED WITH LA NINA CONDITIONS HAVE
DIMINISHED, AND ENSO NEUTRAL CONDITIONS HAVE BEEN IN PLACE SINCE LAST MONTH.
ONE REMNANT OF PRIOR LA NINA CONDITIONS OBSERVED DURING THE MONTH OF MARCH WAS
ANOMALOUSLY ABOVE NORMAL OUTGOING LONGWAVE RADIATION NEAR THE DATE LINE
INDICATING SUPPRESSED CONVECTION AND ANOMALOUSLY BELOW NORMAL OUTGOING LONGWAVE
RADIATION OVER THE NORTHERN MARITIME CONTINENT AND FAR WESTERN PACIFIC, WHERE
CONVECTION WAS ENHANCED. THIS PATTERN MAY HAVE BEEN SOMEWHAT DUE TO AN ACTIVE
SUBSEASONAL MADDEN JULIAN OSCILLATION (MJO). CURRENTLY, THE MJO IS INACTIVE, AS
INDICATED BY THE WHEELER AND HENDON RMM INDEX. IN CONSIDERATION OF THE CURRENT
MJO AND ENSO INDICES, MJO AND ENSO DO NOT HAVE AN IMPACT ON THE APRIL CLIMATE
OUTLOOK.

ANOMALOUSLY ABOVE NORMAL SNOW PACK AND SOIL MOISTURE OVER THE WESTERN CONUS,
AND BELOW NORMAL SOIL MOISTURE OVER MUCH OF THE EASTERN CONUS, AS WELL AS ABOVE
NORMAL SEA SURFACE TEMPERATURES NEAR THE GULF COAST, WERE CONSIDERED IN THE
APRIL CLIMATE OUTLOOK. HOWEVER, THE HALF-MONTH LEAD APRIL 2017 OUTLOOK RELIES
PRIMARILY ON MONTHLY FORECASTS FROM DYNAMICAL MODELS, INCLUDING THE CFS AND THE
NMME, ALSO CONSIDERING WEEK 3-4 FORECASTS FROM THE CFS AND ECMWF ENSEMBLE
PREDICTION SYSTEMS.

THE APRIL 2017 TEMPERATURE OUTLOOK INDICATES ENHANCED PROBABILITIES OF ABOVE
NORMAL TEMPERATURES FOR MUCH OF THE CONUS, AS WELL AS ALASKA. DECADAL TIMESCALE
TEMPERATURE TRENDS PLAY A SIGNIFICANT ROLE IN INCREASING THE PROBABILITIES OF
ABOVE NORMAL TEMPERATURES FROM THE SOUTHWEST, ACROSS THE SOUTHERN CONUS, AND
FOR MUCH OF THE EASTERN CONUS, AS WELL AS ALASKA. NMME PROBABILITIES,
CALIBRATED USING MULTI-DECADAL HINDCASTS, INDICATE THE GREATEST PROBABILITIES
FOR ABOVE NORMAL TEMPERATURES TO BE ALONG THE GULF COAST FOR APRIL. THE
PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE ENHANCED IN THIS REGION BY
OBSERVED AND PREDICTED ABOVE NORMAL SEA SURFACE TEMPERATURES FOR THE GULF OF
MEXICO. CALIBRATED NMME PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ARE WEAKLY
ENHANCED OVER THE SOUTHWEST. BELOW NORMAL SOIL MOISTURE IN MUCH OF THE EASTERN
CONUS MAY PLAY A ROLE IN INCREASING THE CHANCES THAT ABOVE NORMAL TEMPERATURES
WILL PERSIST FOR APRIL MEAN TEMPERATURES. ABOVE NORMAL SNOW PACK IN THE WEST,
AS WELL AS A PREDICTED TROUGH OVER THE WEST IN CFS AND ECMWF WEEK 3-4
FORECASTS, ALSO INDICATE LOWER PROBABILITIES OF ABOVE NORMAL TEMPERATURES OVER
MUCH OF THE WEST. FOR THE FOUR CORNERS REGION, WHERE DECADAL TEMPERATURE TRENDS
ARE A GREATER FRACTION OF INTERANNUAL TEMPERATURE VARIABILITY, A SMALL
ENHANCEMENT OF ABOVE NORMAL TEMPERATURE PROBABILITIES IS INDICATED.

THE APRIL 2017 PRECIPITATION OUTLOOK IS BASED PRIMARILY ON THE PRECIPITATION
FORECASTS FROM THE CFS AND NMME. CALIBRATED PROBABILITIES OF ABOVE MEDIAN
PRECIPITATION ARE GREATEST ALONG THE WESTERN GULF COAST FROM TEXAS TO THE
FLORIDA PANHANDLE, AS INDICATED BY THE NMME, WITH PREDICTED SOUTHERLY FLOW FROM
THE GULF OF MEXICO. RECENT INITIALIZATIONS OF THE CFS PREDICT A PERSISTENT
POSITIVE MID-LEVEL HEIGHT ANOMALY OVER THE NORTH PACIFIC FOR APRIL. DOWNSTREAM
OF THIS POSITIVE ANOMALY, A RELATIVE TROUGH IS PREDICTED OVER THE WESTERN
CONUS, AND A POSITIVE HEIGHT ANOMALY IS PREDICTED OVER THE EASTERN CONUS INTO
THE NORTH ATLANTIC. THIS CIRCULATION FORECAST IS ALSO SUPPORTED BY WEEK 3-4
FORECASTS FROM BOTH THE CFS AND ECMWF ENSEMBLES. THE PROBABILITIES OF BELOW
MEDIAN PRECIPITATION ARE ENHANCED SLIGHTLY FOR COASTAL REGIONS OF THE PACIFIC
NORTHWEST, TO THE WEST OF THE PREDICTED TROUGH, WHILE PROBABILITIES OF ABOVE
MEDIAN PRECIPITATION ARE SLIGHTLY INCREASED OVER THE NORTHERN AND CENTRAL
PLAINS, AHEAD OF THE PREDICTED TROUGH. PROBABILITIES OF BELOW MEDIAN
PRECIPITATION ARE ALSO SLIGHTLY ENHANCED FOR THE ALEUTIAN ISLANDS, AS INDICATED
BY THE NMME CONSENSUS FORECAST.


FORECASTER: DAN COLLINS


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



THE NEXT MONTHLY OUTLOOK...FOR MAY ... WILL BE ISSUED ON THU APR 20 2017


THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD.

$$

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