30 Day Narrative

865 
FXUS07 KWBC 181230
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EDT THU MAY 18 2017
30-DAY OUTLOOK DISCUSSION FOR JUNE 2017
ENSO-NEUTRAL CONDITIONS PERSISTED DURING APRIL, WITH NEAR-AVERAGE SEA SURFACE 
TEMPERATURES (SSTS) OBSERVED ACROSS THE CENTRAL EQUATORIAL PACIFIC, AND 
ABOVE-AVERAGE SSTS IN THE FAR EASTERN PACIFIC. A RESERVOIR OF SUBSURFACE WARMTH 
CONTINUES TO BE OBSERVED NEAR THE DATE LINE, CENTERED AT A DEPTH OF ABOUT 150 
METERS. MAXIMUM TEMPERATURE ANOMALIES RANGE FROM ABOUT 3-5 DEGREES C 
ABOVE-AVERAGE. LOW-LEVEL (850-HPA) WIND ANOMALIES AVERAGED CLOSE TO NORMAL 
DURING THE PAST 30-DAYS. FOR THE SAME TIME PERIOD, THE OUTGOING LONGWAVE 
RADIATION (OLR) PATTERN (WHICH SERVES AS A PROXY FOR CONVECTIVE ANOMALIES 
ACROSS THE TROPICAL PACIFIC) DEPICTED AN AREA OF ENHANCED CONVECTION SOUTH OF 
THE EQUATOR FROM ABOUT 160E TO 125W, OR FROM ABOUT THE SOLOMON ISLANDS EASTWARD 
ACROSS THE SOUTH PACIFIC TO THE PITCAIRN ISLANDS. SUPPRESSED CONVECTION WAS 
NOTED ROUGHLY WITHIN THE SAME LONGITUDE BAND, THOUGH NORTH OF THE EQUATOR. THIS 
OLR FIELD IS NOT REPRESENTATIVE OF EITHER AN EL NINO OR A LA NINA. 
THE MADDEN-JULIAN OSCILLATION (MJO) WAS ACTIVE SINCE LATE APRIL, WITH THE 
ENHANCED CONVECTIVE PHASE CURRENTLY OVER THE INDIAN OCEAN. DURING THE NEXT TWO 
WEEKS, THE MJO IS FORECAST TO EXHIBIT EASTWARD PROPAGATION ACROSS THE INDIAN 
OCEAN AND MARITIME CONTINENT, BUT WITH VERY LOW AMPLITUDE. THEREFORE, THE MJO 
IS NOT LIKELY TO PLAY A SIGNIFICANT ROLE IN THE MONTHLY VARIABILITY OVER NORTH 
AMERICA DURING JUNE. ANTECEDENT SOIL MOISTURE WAS ALSO CONSIDERED FOR THE JUNE 
TEMPERATURE AND PRECIPITATION OUTLOOKS. SOIL MOISTURE IS ANOMALOUSLY HIGH OVER 
PORTIONS OF THE MIDWEST, AND SOUTH-CENTRAL PARTS OF BOTH THE MISSISSIPPI VALLEY 
AND GREAT PLAIN REGIONS. AT THIS TIME OF YEAR, THERE IS A SIGNIFICANT NEGATIVE 
CORRELATION BETWEEN SURFACE TEMPERATURE AND PRECIPITATION IN THIS GENERAL AREA; 
THAT IS, RELATIVELY COOL AND WET CONDITIONS OFTEN GO HAND-IN-HAND.
DYNAMICAL MODELS FROM THE NMME SUITE GENERALLY INDICATED ABOVE-NORMAL MEAN 
TEMPERATURES FOR PORTIONS OF THE WESTERN, SOUTHERN, AND EASTERN CONUS, AND FOR 
MUCH OF WESTERN ALASKA. PROBABILISTIC AND CALIBRATED VERSIONS OF THE NMME TOOL 
WERE CONSIDERED FIRST-GUESS FIELDS FOR THE JUNE OUTLOOK. THE UNCALIBRATED NMME 
TEMPERATURE FORECAST APPEARED TO BE TOO WARM ACROSS THE MIDWESTERN STATES, 
WHERE CALCULATED SOIL MOISTURE RANKING PERCENTILES WERE EASILY IN EXCESS OF 
70-80 PERCENT. THE CFS, THE CANADIAN MODEL (CMC1 CANCM3), AND THE NASA MODEL 
PREDICTED BELOW-NORMAL TEMPERATURES OVER PORTIONS OF THE NORTHERN AND CENTRAL 
ROCKIES, AND CENTRAL AND SOUTHERN PLAINS. THE OFFICIAL TEMPERATURE OUTLOOK FOR 
JUNE INCLUDES AN AREA OF FAVORED BELOW-NORMAL TEMPERATURES OVER MUCH OF WYOMING 
AND COLORADO, ESPECIALLY IN LIGHT OF THE NEGATIVE TEMPERATURE-PRECIPITATION 
CORRELATIONS NOTED EARLIER, AND THE FACT THAT THE ONE PRECIPITATION SIGNAL THAT 
IS CONSIDERED RELIABLE IS THE AREA OF PREDICTED ABOVE-MEDIAN PRECIPITATION OVER 
THIS SAME GENERAL REGION. OTHER MODEL SOLUTIONS, SUCH AS THOSE FROM GFDL AND 
NCAR, APPEAR TO BE TOO BULLISH ON THEIR PREDICTION OF NEARLY COAST-TO-COAST 
WARMTH ACROSS THE CONUS. IN WESTERN ALASKA, MOST (BUT NOT ALL) OF THE NMME 
SUITE PREDICTS ABOVE-NORMAL TEMPERATURES. RELATIVELY WARM SSTS, AND THE 
UNUSUALLY LARGE EXPANSE OF OPEN (ICE-FREE) WATER WEST AND SOUTHWEST OF BARROW 
BY MID-MAY, FAVOR ABOVE-NORMAL TEMPERATURES FOR THE WESTERN PORTION OF THE 
NORTH SLOPE.
THE JUNE PRECIPITATION OUTLOOK ALSO USES THE PROBABILISTIC AND CALIBRATED 
VERSIONS OF THE NMME AS ITS STARTING POINT. THE ONLY SIGNAL WHICH APPEARED 
RELIABLE IS AN AREA OF EXPECTED ABOVE-MEDIAN PRECIPITATION OVER THE VICINITY OF 
THE ROCKIES, AND CENTRAL AND SOUTHERN PLAINS. THE CFS, IMME, CANADIAN MODEL 
(CMC2 CANCM4), AND TO A LESSER DEGREE THE NASA MODEL, LEND SUPPORT FOR THIS WET 
SIGNAL. IN CONTRAST, THE GFDL FLOR MODEL PREDICTS BELOW-MEDIAN PRECIPITATION 
ACROSS THIS PART OF THE CONUS, WHILE THE GFDL CM2.1 AND NCAR MODELS PREDICT 
SOMETHING IN-BETWEEN THE TWO EXTREMES. ELSEWHERE, WHICH INCLUDES A LARGE 
PORTION OF THE CONUS AND ALL OF ALASKA, PRECIPITATION SIGNALS ARE EITHER TOO 
WEAK OR TOO INCOHERENT TO BE OF MUCH USE.
FORECASTER: ANTHONY ARTUSA
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 JUN WILL BE ISSUED ON WED MAY 31 2017
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD.
$$