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 2016
    1.5mn JJA 2016
    2.5mn JAS 2016
    3.5mn ASO 2016
    4.5mn SON 2016
    5.5mn OND 2016
    6.5mn NDJ 2016
    7.5mn DJF 2016
    8.5mn JFM 2017
    9.5mn FMA 2017
   10.5mn MAM 2017
   11.5mn AMJ 2017
   12.5mn MJJ 2017
    0.5mn May 2016


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
300 PM EDT SAT APR 30 2016

30-DAY OUTLOOK DISCUSSION FOR MAY 2016

THE UPDATED MONTHLY OUTLOOK FOR MAY IS QUITE SIMILAR TO THAT ISSUED ON APRIL
21. THE FORECAST IS MODIFIED BY TAKING ADVANTAGE OF SHORT-TERM WEATHER AND
CLIMATE FORECASTS ISSUED WITHIN THE PAST ONE TO TWO DAYS. SINCE THE
IMPLEMENTATION OF THE EXPERIMENTAL WEEKS 3+4 FORECAST, THE ZERO-LEAD MONTHLY
FORECASTS LARGELY SERVE THE ROLE OF AGGREGATING FORECASTS FOR WEEK-1 ISSUED BY
WPC AND THE WEEKS 2-4 FORECASTS ISSUED BY CPC. AT THIS TIME, SUCH AN EFFORT IS
LARGELY SUBJECTIVE, BUT BENEFITS FROM THE CFS FORECASTS, FOR WHICH WE HAVE AN
EXPLICIT MAY FORECAST BASED ON THE MOST RECENT MODEL RUNS.

EARLY IN THE MONTH, ANOMALOUS TROUGHING IS FORECAST FOR MUCH OF THE CONUS FROM
THE SOUTHWEST TO THE EASTERN U.S. THIS IS EXPECTED TO CONTRIBUTE TO
BELOW-NORMAL TEMPERATURES AND ABOVE-MEDIAN PRECIPITATION FOR PARTS OF THE GREAT
BASIN, ROCKIES, SOUTHWEST, AND SOUTHERN PLAINS. UNSETTLED WEATHER AND
COOLER-THAN-NORMAL TEMPERATURES ARE FORECAST TO EXTEND TOWARD THE EAST COAST
AND GREAT LAKES EARLY IN THE MONTH. HOWEVER, A WARMING TREND IS EXPECTED DURING
WEEK-2 FOR MUCH OF THE EASTERN U.S., AND DYNAMICAL AND STATISTICAL GUIDANCE FOR
WEEKS 3+4 FAVORS A WARMER-THAN-NORMAL PATTERN CENTERED ON THE EAST-CENTRAL
CONUS. COMBINING THESE EFFECTS FAVORS A MODEST TILT TOWARD ABOVE-NORMAL
TEMPERATURES FOR THE EASTERN CONUS FOR THE MONTH. FARTHER WEST, PROBABILITIES
OF BELOW-NORMAL TEMPERATURES ARE ENHANCED RELATIVE TO THE MID-MONTH OUTLOOK,
WHERE MODEL GUIDANCE STRONGLY FAVORS BELOW-NORMAL 500-HPA HEIGHTS FOR THE MONTH.

THE PRECIPITATION OUTLOOK TAKES ADVANTAGE OF HEAVY PRECIPITATION FORECAST OVER
THE NEXT FEW DAYS, WHILE ALSO ATTEMPTING TO UTILIZE LOW-FREQUENCY CLIMATE
VARIABILITY. THEREFORE, PROBABILITIES ARE HIGHEST WHERE THERE IS A CONFLUENCE
OF SHORT-TERM PRECIPITATION ANOMALIES AND LOWER FREQUENCY CLIMATE SIGNALS. AS
WITH TEMPERATURE, THE SPATIAL DISTRIBUTION OF PROBABILITIES IS QUITE SIMILAR TO
THE 0.5-MONTH LEAD OUTLOOK.

THE PREVIOUS DISCUSSION ISSUED WITH THE 0.5-MONTH LEAD FORECAST FOLLOWS.
-------------------------------------------------------------------------

THE MAY 2016 OUTLOOK IS CONSTRUCTED BASED ON THE LOW-FREQUENCY CLIMATE SIGNALS
MANIFEST IN THE DYNAMICAL AND STATISTICAL GUIDANCE. MOST GUIDANCE IS IN GOOD
AGREEMENT ON THE GENERAL STRUCTURE OF FORECAST PROBABILITIES, AND SHORTER TERM
OUTLOOKS ARE CONSULTED TO REFINE THE FORECAST. THERE IS LITTLE IN THE WAY OF
COHERENT MJO ACTIVITY TO INFLUENCE THE OUTLOOK; THE MJO'S INFLUENCE IS
DIMINISHED IN THE WARM SEASON, AND PLAYS NO ROLE HERE IN INFORMING THE MONTHLY
FORECAST. SOIL MOISTURE, HOWEVER, IS TAKEN INTO ACCOUNT, AS INCREASING INCIDENT
SOLAR RADIATION ALLOWS IT TO EXERT MORE INFLUENCE ON LOCAL TEMPERATURES.

THE CALIBRATED NMME TEMPERATURE PROBABILITIES INDICATE A FAIRLY WEAK TILT
TOWARD WARMER-THAN-NORMAL TEMPERATURES ACROSS THE NORTHERN TIER OF THE CONUS,
ALASKA, AND PARTS OF THE EASTERN CONUS. A NOTABLE WEAKNESS IS FORECAST OVER THE
SOUTH-CENTRAL AND SOUTHWESTERN U.S. THIS IS GENERALLY CONSISTENT WITH LAGGED
ENSO REGRESSIONS (USING LATE WINTER NINO 3.4 VALUES), OBJECTIVE COMPOSITE
ANALOGS BASED ON THE RECENTLY OBSERVED SSTS IN THE TROPICAL AND NORTHERN
PACIFIC AND ATLANTIC BASINS, AS WELL AS STATISTICALLY DERIVED LOCAL SOIL
MOISTURE IMPACTS. THE SECULAR TREND EXPLAINS LESS VARIANCE ON MONTHLY
TIMESCALES THAN ON SEASONAL TIMESCALES, BUT GENERALLY SUPPORTS THE SPATIAL
STRUCTURE OF FORECAST TEMPERATURE PROBABILITIES.

ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES ARE INDICATED FOR MUCH OF
THE WESTERN, NORTHERN, AND EASTERN CONUS, BASED ON THE ABOVE FACTORS. THE
LOWEST PROBABILITIES ARE FORECAST OVER NORTHERN NEW ENGLAND AND THE NORTHERN
PLAINS. THE FORMER IS DUE TO HIGHER-FREQUENCY PATTERNS THAT FAVOR ANOMALOUS
NORTHERLY FLOW INTO EARLY MAY FOR THAT REGION, WHILE THE LATTER IS DUE TO
TRENDS AND SOIL MOISTURE TOOLS. THE LATEST CFS FORECASTS, WEEK 3/4 GUIDANCE
FROM BOTH THE CFS AND ECMWF, SOIL MOISTURE CONSIDERATIONS, AND LAGGED ENSO
REGRESSIONS FAVOR ENHANCED PROBABILITIES OF BELOW-NORMAL TEMPERATURES ACROSS A
PORTION OF THE SOUTHWESTERN AND SOUTH-CENTRAL CONUS.

ALL OF THE AFOREMENTIONED OBJECTIVE GUIDANCE IS IN FAIRLY GOOD AGREEMENT ON THE
FORECAST PRECIPITATION OUTLOOK AS WELL. MODEST PROBABILITIES FAVORING
ABOVE-MEDIAN PRECIPITATION ARE DEPICTED FOR MUCH OF THE CENTRAL AND SOUTHERN
CONUS, EXTENDING WESTWARD TO PARTS OF CALIFORNIA AND THE GREAT BASIN.


FORECASTER: STEPHEN BAXTER


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 JUN ... WILL BE ISSUED ON THU MAY 19 2016


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