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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 2014
    1.5mn MJJ 2014
    2.5mn JJA 2014
    3.5mn JAS 2014
    4.5mn ASO 2014
    5.5mn SON 2014
    6.5mn OND 2014
    7.5mn NDJ 2014
    8.5mn DJF 2014
    9.5mn JFM 2015
   10.5mn FMA 2015
   11.5mn MAM 2015
   12.5mn AMJ 2015
    0.5mn Apr 2014


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HOME> Outlook Maps>Seasonal Forecast Discussion
 
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300PM EDT MONDAY MAR 31 2014

30-DAY OUTLOOK DISCUSSION FOR APRIL 2014

ADJUSTMENT ON MARCH, 31 IS BASED MAINLY ON THREE TOOLS, AND ALL THREE REFLECT
THE IMPACT OF THE MOST RECENT ATMOSPHERIC CONDITIONS ON THE WEATHER OF THE
FIRST SEVERAL DAYS OF APRIL 2014. THE FIRST TOOL IS THE GFS ENSEMBLE. SECOND
TOOL IS THE WPC 5-DAY PRECIPITATION FORECAST, WHICH USES NWP MODELS FROM
OUTSIDE NCEP AS WELL. THIRD TOOL IS THE 16 MEMBER CFS USING INITIAL CONDITIONS
FROM MARCH 30 6Z THROUGH MARCH, 31 0Z. THE LATTER TOOL, AN AVERAGE FOR ALL OF
APRIL, IS IN THEORY IDEAL IN COMBINING SHORT RANGE WEATHER INFORMATION AND
SHORT-TERM CLIMATE SIGNALS.

FOR THE MOST PART THE TEMPERATURE FORECAST NEEDED ONLY SLIGHT ADJUSTMENTS.
BECAUSE OF WARMTH IN THE EARLY DAYS OF APRIL IN EAST-CENTRAL AND SOUTHEASTERN
U.S., WE MOVED THE SOUTHERN BOUNDARY OF THE AREA OF FAVORED BELOW AVERAGE
TEMPERATURE CENTERED IN THE GREAT LAKES A LITTLE TO THE NORTH.

PRECIPITATION IS MORE COMPLICATED. THE EXPECTED PRECIPITATION DURING APRIL 1-2
ALONG THE WEST COAST AND EVEN IN COASTAL SOUTHERN CALIFORNIA MADE US REMOVE THE
AREA OF PREDICTED BELOW MEDIAN PRECIPITATION, INDICATED AT MID-MONTH, FROM MUCH
OF THE MAP, ESPECIALLY ALONG THE IMMEDIATE WEST COAST. THE ONLY SURVIVING
FORECAST FOR ENHANCED CHANCES FOR BELOW MEDIAN PRECIPITATION IS IN SOUTHEASTERN
CA, AND PARTS OF AZ, NV, UT AND CO. IN THE FIRST FEW DAYS OF APRIL THERE WILL
BE SEVERAL PRECIPITATION EVENTS IN THE TENNESSEE AND OHIO VALLEY SO WE ADDED
ENHANCED PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION IN THAT AREA.

THE APRIL TEMPERATURE OUTLOOK INDICATES AN AREA OF FAVORED BELOW NORMAL MONTHLY
MEAN TEMPERATURES FOR PORTIONS OF THE NORTHERN PLAINS, GREAT LAKES, AND
NORTHEAST. SOME OF THE COLD MAY BE AMPLIFIED NEAR THE SHORES AROUND THE GREAT
LAKES SINCE ICE COVER IS PRESENTLY HIGH AND, ONCE UNFROZEN, WATER TEMPERATURE
WILL LIKELY BE BELOW NORMAL FOR SOME TIME. TOOLS FAVOR ABOVE NORMAL
TEMPERATURES FOR MUCH OF THE SOUTHWEST QUARTER OF THE CONUS WITH A WEAK
EXTENSION ACROSS TEXAS INTO THE COASTAL AREAS OF THE SOUTHEAST. MUCH OF ALASKA
HAS ENHANCED PROBABILITY FOR ABOVE NORMAL TEMPERATURE.

THE APRIL OUTLOOK FAVORS BELOW-MEDIAN PRECIPITATION IN THE SOUTHEASTERN PART OF
CALIFORNIA, AND SOME OF NEVADA, ARIZONA, UTAH AND COLORADO. ABOVE MEDIAN
PRECIPITATION IS FAVORED IN PARTS OF THE TENNESSEE AND OHIO VALLEY. THE REST OF
CONUS AND ALASKA IS DESIGNATED EC.





THE TWO-WEEK OLD MID-MONTH MESSAGE IS BELOW:

ENSO-NEUTRAL CONDITIONS REMAIN IN PLACE AND ARE NOT DIRECTLY CONSIDERED FOR
APRIL. THE FIRST GUESS FOR APRIL IS THE 0.5 MONTH LEAD MAM SEASONAL FORECAST
ISSUED ONE MONTH AGO. THERE IS STRONG SUPPORT FOR CONTINUATION OF THE
TEMPERATURE PATTERN THAT RESEMBLES WHAT WE HAVE SEEN ALL WINTER. DYNAMICAL
TOOLS AND SOME OF THE EMPIRICAL TOOLS SUPPORT THE CONTINUATION OF THIS PATTERN
FOR AT LEAST APRIL. THE IMPACT ON THE APRIL OUTLOOK WOULD BE WARMTH IN THE
SOUTHWEST AND COLD IN THE NORTHERN PLAINS AND NORTHEAST.  COVERAGE AND
PROBABILITIES ARE QUITE HIGH FOR A MONTHLY TEMPERATURE FORECAST.

THE APRIL TEMPERATURE OUTLOOK INDICATES AN AREA OF FAVORED BELOW NORMAL MONTHLY
MEAN TEMPERATURES FOR PORTIONS OF THE NORTHERN PLAINS, GREAT LAKES, TENNESSEE
AND OHIO VALLEYS AND NORTHEAST. SOME OF THE COLD MAY BE AMPLIFIED NEAR THE
SHORES AROUND THE GREAT LAKES SINCE ICE COVER IS PRESENTLY HIGH AND, ONCE
UNFROZEN, WATER TEMPERATURE WILL BE BELOW NORMAL FOR SOME TIME. TOOLS FAVOR
ABOVE NORMAL TEMPERATURES FOR MUCH OF THE SOUTHWEST QUARTER OF THE CONUS WITH A
WEAK EXTENSION ACROSS TEXAS INTO THE COASTAL AREAS OF THE SOUTHEAST.
ANTICIPATED RIDGING ACROSS PORTIONS OF WESTERN NORTH AMERICA INTO ALASKA
SUPPORT ABOVE NORMAL TEMPERATURES FOR MUCH OF ALASKA. BELOW AVERAGE SEA ICE
EXTENT AND ABOVE AVERAGE SEA SURFACE TEMPERATURES IN THE BERING SEA ALSO
SUPPORT THIS FORECAST.

IN AREAS WHERE CLIMATE SIGNALS ARE WEAK AND/OR NOT RELIABLE, EQUAL CHANCES (EC)
OF BELOW-, NEAR- AND ABOVE-NORMAL MEAN MONTHLY TEMPERATURES ARE INDICATED.

THE CONFIDENCE IN THE PRECIPITATION OUTLOOK IS MUCH LESS THAN THAT FOR
TEMPERATURE, WHICH IS OFTEN THE CASE. THE NMME, CFS, AS WELL AS THE CCA
STATISTICAL TOOL, FAVOR BELOW-MEDIAN PRECIPITATION IN THE SOUTHWEST FOR ALL OF
CALIFORNIA, AND SOME OF NEVADA, ARIZONA AS WELL AS ALONG THE WEST COAST INTO
THE ALASKA PANHANDLE. THE REST OF CONUS IS DESIGNATED EC.

ALL OF THE ABOVE WILL BE REVISITED WHEN DOING THE MONTHLY UPDATE OM MARCH 31.


IN AREAS WHERE CLIMATE SIGNALS ARE WEAK AND/OR NOT RELIABLE, EQUAL CHANCES (EC)
OF BELOW-, NEAR- AND ABOVE-MEDIAN TOTAL MONTHLY PRECIPITATION ARE INDICATED.

THE MAIN FACTORS THAT USUALLY INFLUENCE THE MONTHLY CLIMATE OUTLOOK INCLUDE:
1) EL NINO AND LA NINA - WHICH COMPRISE ENSO. IMPACTS OF THESE EVENTS ARE
SUMMARIZED BY SEPARATING 3-MONTH OBSERVATIONS FROM THREE OR MORE DECADES INTO
EL NINO, NEUTRAL AND LA NINA SETS, AVERAGING EACH SEPARATELY, AND THEN
COMPUTING ANOMALIES. THESE ARE CALLED "COMPOSITES" AND USED AT TIMES TO
SUBJECTIVELY MODIFY THE FORECAST.
2) TRENDS - APPROXIMATED BY THE OCN TOOL AS THE DIFFERENCE BETWEEN THE MOST
RECENT 10-YEAR MEAN OF TEMPERATURE OR 15-YEAR MEAN OF PRECIPITATION FOR A GIVEN
LOCATION AND TIME OF YEAR AND THE 30-YEAR CLIMATOLOGY PERIOD (CURRENTLY
1981-2010).
3) THE TROPICAL 30-60 DAY OSCILLATION - CALLED THE MADDEN JULIAN OSCILLATION
(MJO) - AFFECTS CLIMATE VARIABILITY WITHIN SEASONS.
4) THE ARCTIC OSCILLATION (AO), THE SIMILAR NORTH ATLANTIC OSCILLATION (NAO),
AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS - WHICH AFFECT THE TEMPERATURE
ANOMALY PATTERN ESPECIALLY DURING BOREAL WINTER AND ARE GENERALLY CONSIDERED TO
HAVE LOW PREDICTABILITY.
5) THE PACIFIC DECADAL OSCILLATION (PDO) - AN ENSO-LIKE PATTERN OF CLIMATE
VARIABILITY AFFECTING THE TROPICS AND THE NORTH PACIFIC AND NORTH AMERICAN
REGIONS, BUT WHICH VARIES ON A MUCH LONGER TIME-SCALE THAN ENSO.
6) PERSISTENTLY DRY OR WET SOILS IN THE SPRING AND SUMMER AND SNOW AND ICE
COVER ANOMALIES IN THE WINTER. THESE FACTORS TEND TO PERSIST FOR LONG PERIODS
AND ACT AS A KIND OF MEMORY IN THE CLIMATE SYSTEM.
7) STATISTICAL FORECAST MODELS - CANONICAL CORRELATION ANALYSIS (CCA),
SCREENING MULTIPLE LINEAR REGRESSION (SMLR), CONSTRUCTED ANALOG (CA), AND
ENSEMBLE CCA (ECCA).
8) DYNAMICAL FORECAST MODELS - INCLUDING THE NCEP CLIMATE FORECAST SYSTEM
VERSION 2 (CFS) AND FOR THE ZERO-LEAD UPDATE FORECASTS THE NCEP GLOBAL ENSEMBLE
FORECAST SYSTEM (GEFS).  AN EXPERIMENTAL FORECAST SYSTEM, THE NATIONAL
MULTI-MODEL ENSEMBLE (NMME), COMPRISED OF SEVERAL DYNAMICAL MODELS IS ALSO USED.


FORECASTER: HUUG VAN DEN DOOL


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 17 2014


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

$$

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