PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 
830 AM EDT THU JUN 21 2018 
 
 
30-DAY OUTLOOK DISCUSSION FOR JULY 2018 
 
THE JULY 2018 TEMPERATURE AND PRECIPITATION OUTLOOKS ARE BASED ON DYNAMICAL 
MODEL GUIDANCE, STATISTICAL TOOLS, CURRENT SOIL MOISTURE CONDITIONS, AND 
POTENTIAL INFLUENCES FROM MODES OF TROPICAL VARIABILITY. ENSO IS NOT A FACTOR 
IN THESE OUTLOOKS SINCE IT IS IN A NEUTRAL STATE AND IS PREDICTED TO REMAIN 
NEUTRAL. 
 
THE MADDEN-JULIAN OSCILLATION (MJO) IS NOT LIKELY TO PLAY A SIGNIFICANT ROLE, 
AS TELECONNECTIONS TO MID-LATITUDE CIRCULATION FEATURES FROM MJO RELATED 
CONVECTION IS TYPICALLY WEAK DURING JULY. THE PREDICTED EVOLUTION OF THE MJO IS 
NOT ONE CONDUCIVE TO THE MJO SUPPORTING TROPICAL CYCLONE DEVELOPMENT IN THE 
EASTERN PACIFIC OR THE ATLANTIC. GIVEN THE PREDICTED STATE OF ENSO AND MJO, 
HIGHER FREQUENCY MODES THAT ARE NOT PREDICTABLE ON MONTHLY TIME SCALES ARE 
LIKELY TO INFLUENCE TROPICAL CYCLONE FORMATIONS, AND THE RESULTANT POTENTIAL 
FOR LARGE MOISTURE INFLUXES INTO THE FORECAST DOMAIN. 
 
MODEL OUTLOOKS FROM THE NMME SUITE, MORE RECENT RUNS FROM THE CFS, AND TRENDS 
FAVOR ABOVE NORMAL TEMPERATURES ACROSS THE WESTERN CONUS, WHERE THE HIGHEST 
ODDS FOR ABOVE NORMAL TEMPERATURES ARE DEPICTED IN THE OFFICIAL OUTLOOK. OVER 
PORTIONS OF THE HIGH PLAINS AND GREAT PLAINS, MANY MODELS INDICATE AN AREA 
WHERE NEAR OR BELOW NORMAL TEMPERATURES ARE FAVORED, WHICH IS IN OPPOSITION TO 
TRENDS, SO EQUAL CHANCES (EC) IS DEPICTED. CURRENT SOIL MOISTURE CONDITIONS AND 
DYNAMICAL MODEL OUTPUT ALSO FAVOR ABOVE NORMAL TEMPERATURES OVER THE CENTRAL 
PLAINS AS WELL AS THE MIDDLE AND LOWER MISSISSIPPI VALLEYS. FURTHER EAST, 
ESPECIALLY ACROSS THE NORTHEAST, TRENDS ALSO CONTRIBUTE TO THE SIGNAL FOR ABOVE 
NORMAL TEMPERATURES. ACROSS THE SOUTHEAST, SOME MODELS HAVE LITTLE TO NO SIGNAL 
FOR TEMPERATURE DEVIATIONS, SO EC IS INDICATED IN THE OFFICIAL OUTLOOK. ACROSS 
ALASKA, TRENDS FAVOR ABOVE NORMAL TEMPERATURES THOUGH MODEL OUTPUTS SHOW A 
WEAKNESS ACROSS EASTERN ALASKA. THE OUTLOOK FAVORS ABOVE NORMAL TEMPERATURES 
OVER WESTERN AND SOUTHERN ALASKA, WHERE MODEL OUTPUT, TRENDS, AND RECENT SST 
OBSERVATIONS ALIGN. 
 
THE PRECIPITATION OUTLOOK IS LESS CERTAIN THAN THE TEMPERATURE OUTLOOK, 
ESPECIALLY OVER THE GREAT PLAINS. MOST OF THE MODELS FROM THE NMME SUITE AND 
THE RECENT CFS RUNS DEPICT A STRONG DRY SIGNAL OVER THE CARIBBEAN AND A STRONG 
WET SIGNAL OVER THE CENTRAL TROPICAL PACIFIC.  MOST OF THE MODELS INDICATE A 
SIGNAL FOR ABOVE NORMAL PRECIPITATION OVER THE SOUTHWEST AND INTO THE CENTRAL 
ROCKIES, WHICH IS CONSISTENT WITH SOME NORTHWARD MOISTURE TRANSPORT OUT OF THE 
EAST PACIFIC, AND AN ACTIVE START TO THE SOUTHWEST MONSOON. THE DRY SIGNAL FROM 
THE CARIBBEAN EXTENDS INTO THE GREAT PLAINS, IMPLYING LESS NORTHWARD MOISTURE 
TRANSPORT FROM THE LOWER LATITUDES. THIS SIGNAL CONFLICTS WITH TRENDS FOR 
PORTIONS OF THE LOWER MISSISSIPPI VALLEY, SO PROBABILITIES ARE MUTED COMPARED 
TO MODEL OUTPUTS.  MODEL HINDCASTS REVEAL LITTLE SKILL IN THE CENTRAL AND 
NORTHERN PLAINS AND TRENDS ARE WEAK IN THOSE AREAS, SO NO SIGNAL FOR EITHER 
WETTER OR DRIER THAN NORMAL CONDITIONS IS DEPICTED IN THE OUTLOOK. TRENDS IN 
THE NORTHEAST FOR THE CORE SUMMER MONTHS FAVOR WETTER CONDITIONS, WHILE RECENT 
CFS OUTPUT SUGGESTS BELOW NORMAL PRECIPITATION FOR THE NORTHEAST, WITH THAT 
SIGNAL FADING OVER THE MID-ATLANTIC. BOTH TRENDS AND MODEL GUIDANCE FAVOR BELOW 
NORMAL PRECIPITATION FOR THE PACIFIC NORTHWEST.  ABOVE AVERAGE PRECIPITATION IS 
FAVORED FOR NORTHERN AND WESTERN ALASKA INCLUDING THE ALEUTIANS, SUPPORTED BY 
MODEL GUIDANCE. ACROSS EASTERN ALASKA, UNCERTAINTY IS GREATER, SO EQUAL CHANCES 
IS INDICATED. 
 
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 JUL WILL BE ISSUED ON SAT JUNE 30 2018 
 
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. 
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