Skip Navigation Links www.nws.noaa.gov 
NOAA logo - Click to go to the NOAA home page National Weather Service   NWS logo - Click to go to the NWS home page
Climate Prediction Center
 
 

CPC Search
About Us
   Our Mission
   Who We Are

Contact Us
   CPC Information
   CPC Web Team

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.

Text Discussions
   90day Prognostic
   30day Prognostic
   Hawaiian
   Tools


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


Tools Used (see Discussion for explanation)
   CCA
   OCN
   CMP
   SMT
   POE
 
HOME> Outlook Maps>Seasonal Forecast Discussion
 
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU APR 20 2017

30-DAY OUTLOOK DISCUSSION FOR MAY 2017

ENSO NEUTRAL CONDITIONS ARE PRESENT ACROSS THE PACIFIC OCEAN.  SOME ATMOSPHERIC
VARIABLES, SUCH AS LOW-LEVEL WINDS AND OUTGOING LONGWAVE RADIATION (OLR) STILL
HAVE SOME RESEMBLANCE TO CANONICAL LA NINA PATTERNS, THOUGH OTHERS (UPPER-LEVEL
WINDS) ARE LESS COHERENT. OLR STILL INDICATES SUPPRESSED (ENHANCED) CONVECTION
NEAR THE DATE LINE (MARITIME CONTINENT). A KEY DIFFERENCE THIS MONTH, IS THAT
THE SUPPRESSED CONVECTION EXTENDS NORTHEASTWARD, RATHER THAN BEING SYMMETRIC
ALONG THE EQUATOR. THIS ASYMMETRY HAS ALLOWED SOME CONVECTION TO DEVELOP FROM
160W TO 120W, JUST SOUTH OF THE EQUATOR.

THE MJO PLAYED A SMALL ROLE IN THE TROPICAL PACIFIC DURING MARCH. SOME SHORTER
PERIOD VARIABILITY WAS EVIDENT ACROSS THE EASTERN PACIFIC, BUT THE PATTERN OVER
THE CENTRAL PACIFIC WAS HIGHLY LINKED TO THE LONG-TERM PATTERN. FORECASTS OF
THE MJO INDICATE AN AMPLIFICATION OVER THE WESTERN PACIFIC, THOUGH THE
INCOHERENCE OF THE OBSERVED SIGNAL INCREASES UNCERTAINTY. THE MJO IS NOT LIKELY
TO PLAY A LARGE ROLE IN THE MONTHLY VARIABILITY OVER NORTH AMERICA DURING MAY.

OTHER FACTORS, SUCH AS ANTECEDENT SOIL MOISTURE AND SNOW PACK, WERE CONSIDERED.
SOIL MOISTURE IS ANOMALOUSLY HIGH OVER PORTIONS OF THE MIDWEST, WHICH HAS A
LAGGED RELATIONSHIP WITH BELOW NORMAL TEMPERATURES. ABOVE NORMAL SNOW PACK OVER
THE CENTRAL AND NORTHERN ROCKIES WAS ALSO CONSIDERED IN THE TEMPERATURE OUTLOOK.

DYNAMIC MODELS FROM THE NMME SUITE GENERALLY INDICATED ABOVE NORMAL
TEMPERATURES FOR MOST OF THE CONUS AND ALASKA. PROBABILITIES WERE WEAKEST FROM
CALIFORNIA TO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. MORE RECENT TRENDS IN
MODEL GUIDANCE (CFS FOR THE MONTH OF MAY, GUIDANCE FOR THE WEEK 3-4 PERIOD,
AND THE LAST FEW DAYS OF THE 8-14 DAY PERIOD) INDICATE A COOL START TO THE
MONTH OVER THE NORTHERN ROCKIES AND GREAT PLAINS. THE OUTLOOK REFLECTS THE
COMBINATION OF NMME MODELS AND MORE RECENT MODEL INPUTS, AS WELL AS THE
ANTECEDENT CONDITIONS MENTIONED ABOVE. THE OUTLOOK INDICATES ABOVE NORMAL
TEMPERATURES ARE FAVORED FOR THE SOUTHWEST, TEXAS, AND FROM THE SOUTHEAST TO
THE GREAT LAKES AND NORTHEAST.

SIGNALS FOR PRECIPITATION ANOMALIES IN THE INDIVIDUAL NMME MODELS ARE QUITE
STRONG, BUT SIGNALS IN THE MEAN ARE QUITE A BIT WEAKER AS THE MODELS EXHIBIT
POOR AGREEMENT IN THE OVERALL PATTERN. AFTER CALIBRATION, WEAK SIGNALS REMAIN
OVER WESTERN ALASKA, THE NORTHERN HIGH PLAINS, THE GREAT LAKES, AND NORTHEAST.
SOME OF THE MODELS IN THE NMME SUITE INDICATED EXTREME ANOMALIES (IN BOTH
TEMPERATURE AND PRECIPITATION), SO THOSE MODELS WERE CONSIDERED OUTLIERS. TO
BROADEN THE MODEL INPUTS AND LESSEN THE IMPACT OF THE EXTREME ANOMALIES, THE
IMME WAS ALSO USED AS AN INPUT FOR THE PRECIPITATION OUTLOOK. THE OFFICIAL
OUTLOOK INDICATES BELOW MEDIAN PRECIPITATION IS FAVORED FOR WESTERN ALASKA, THE
ALASKA PANHANDLE, AND THE GREAT LAKES, ALL CONSISTENT WITH MODEL OUTPUT. ABOVE
MEDIAN PRECIPITATION IS FAVORED OVER THE NORTHERN HIGH PLAINS AND ALONG THE
GULF COAST, CONSISTENT WITH MODEL OUTPUT AND IN SOME CASES, TRENDS.


FORECASTER: MATTHEW ROSENCRANS


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.



AN UPDATED MONTHLY OUTLOOK... FOR MAY WILL BE ISSUED ON SUN APRIL 30 2017


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

$$

NOAA/ National Weather Service
National Centers for Environmental Prediction
Climate Prediction Center
5200 Auth Road
Camp Springs, Maryland 20746
Climate Prediction Center Web Team
Page last modified: January 17, 2006
Disclaimer
Information Quality
Credits
Glossary
Privacy Policy
Freedom of Information Act
About Us
Career Opportunities