FXUS07 KWBC 151231 PMD30D PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD 830 AM EDT THU MAR 15 2018 30-DAY OUTLOOK DISCUSSION FOR APRIL 2018 THE OUTLOOK FOR APRIL 2018 IS BASED PRIMARILY ON A WIDE RANGE OF DYNAMICAL AND STATISTICAL MODELS AND TOOLS SUCH AS THE CFS, THE NMME SUITE OF CLIMATE MODELS, THE CONSTRUCTED ANALOG BASED ON SEA SURFACE TEMPERATURES (CA-SST), AND THE CONSTRUCTED ANALOG BASED ON SOIL MOISTURE (CAS). OTHER CONSIDERATIONS INCLUDED DECADAL TEMPERATURE AND PRECIPITATION TRENDS, CURRENT SEA SURFACE TEMPERATURES ALONG THE WEST COAST OF ALASKA, NEAR-COASTAL SEA ICE CONDITIONS IN NORTHWESTERN ALASKA, INITIAL CONDITIONS, CLIMATOLOGY AND OBSERVED SOIL MOISTURE CONDITIONS OVER THE PAST 30-DAYS. LA NINA CONDITIONS CONTINUE INTO MID-MARCH, WITH NEGATIVE SST ANOMALIES OBSERVED ACROSS THE CENTRAL AND EASTERN EQUATORIAL PACIFIC OCEAN FROM ABOUT 170W TO THE COAST OF SOUTH AMERICA. BOTH THE LA NINA AND THE COUPLED ATMOSPHERIC RESPONSE TO THIS COLD EVENT WEAKENED CONSIDERABLY DURING THE PAST MONTH. THE OUTGOING LONGWAVE RADIATION (OLR) ANOMALY MAP VALID FOR THIS SAME PERIOD DEPICTS POSITIVE OLR ANOMALIES DUE TO REDUCED CONVECTION NEAR AND JUST NORTH OF THE EQUATOR IN THE VICINITY OF THE DATE LINE, AND NEGATIVE OLR ANOMALIES DUE TO ENHANCED CONVECTION OVER PARTS OF THE MARITIME CONTINENT AND WESTERN PACIFIC. CPC'S ENSO DIAGNOSTIC DISCUSSION (MARCH 8TH) EXPECTS A TRANSITION FROM LA NINA TO ENSO-NEUTRAL TO BE MOST LIKELY (~55% CHANCE) DURING THE MARCH-MAY SEASON, WITH NEUTRAL CONDITIONS LIKELY TO CONTINUE INTO THE SECOND HALF OF THE YEAR. THE MADDEN JULIAN OSCILLATION (MJO) HAS WEAKENED CONSIDERABLY DURING THE PAST FEW WEEKS, WITH THE ENHANCED CONVECTIVE PHASE CURRENTLY LOCATED OVER THE EASTERN INDIAN OCEAN. DURING THE NEXT TWO WEEKS, THE MJO IS PREDICTED TO WEAKEN FURTHER, AND ITS EFFECTS ON THE U.S. TEMPERATURE AND PRECIPITATION OUTLOOKS FOR APRIL ARE CONSIDERED MINIMAL. THE TEMPERATURE OUTLOOK FOR APRIL 2018 DEPICTS ELEVATED ODDS FOR BELOW NORMAL TEMPERATURES OVER SOUTHEASTERN MAINLAND ALASKA AND THE PANHANDLE, AND FROM WASHINGTON STATE EASTWARD ACROSS THE NORTHERN ROCKIES, THE NORTHERN PLAINS (PERHAPS AS FAR SOUTH AS NEBRASKA), AND MUCH OF THE UPPER MISSISSIPPI VALLEY. THIS AREA OF FAVORED BELOW NORMAL TEMPERATURES HAS BROAD SUPPORT FROM THE CALIBRATED AND UNCALIBRATED NMME ENSEMBLE MEAN, CFS, CA-SST, AND DECADAL TRENDS. OFTEN DURING THE WANING STAGES OF A LA NINA, THE ANOMALOUS COLD SIGNAL OVER THE NORTH-CENTRAL CONUS SHIFTS FARTHER WEST INTO THE PACIFIC NORTHWEST, LENDING ADDITIONAL SUPPORT TO THE TEMPERATURE OUTLOOK. THE GREATEST PROBABILITIES FOR BELOW NORMAL TEMPERATURES, IN EXCESS OF 50 PERCENT, ARE FORECAST OVER NORTH DAKOTA AND SMALL PORTIONS OF NEIGHBORING STATES. ABOVE NORMAL TEMPERATURES ARE FAVORED ACROSS APPROXIMATELY THE SOUTHERN HALF AND EASTERN THIRD OF THE CONUS, BASED IN LARGE PART ON THE NMME, CFS, DECADAL TEMPERATURE TRENDS, AND TO A LESSER DEGREE, THE CA-SST. THE NMME (ESPECIALLY THE CALIBRATED VERSION) AND THE CFS ALSO PREDICT A RELATIVE WEAKNESS IN THE PREDICTED ANOMALOUS WARMTH FROM APPROXIMATELY THE EASTERN CORN BELT AREA EASTWARD ACROSS THE OHIO AND TENNESSEE VALLEYS, THE MID-ATLANTIC AND NORTHEAST. A FEW OF THE MORE RECENT CFS RUNS, INCLUDING TODAY'S SOLUTION, CAST DOUBT ON HIGHER PROBABILITIES FOR ABOVE NORMAL TEMPERATURES OVER THE NORTHEAST CONUS. ACCORDINGLY, ONLY MODEST TILTS IN THE PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ARE FORECAST FOR THE NORTHEAST. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED OVER WESTERN ALASKA, SUPPORTED BY THE NMME AND LATEST FEW RUNS OF THE CFS, CA-SST, RELATIVELY WARM COASTAL SSTS, AND REDUCED SEA ICE COVERAGE RELATIVE TO NORMAL (NORTHWESTERN ALASKA). THE GREATEST ODDS FOR ABOVE NORMAL TEMPERATURES ARE INDICATED OVER THE BERING SEACOAST OF ALASKA,AND ALONG THE SOUTHERN TIER OF THE CONUS (BOTH IN EXCESS OF 50 PERCENT). THE PRECIPITATION OUTLOOK FOR APRIL 2018 FAVORS ABOVE NORMAL PRECIPITATION OVER WESTERN AND NORTHERN ALASKA, FROM THE NORTHERN ROCKIES TO MINNESOTA, AND FROM NORTHEASTERN ARKANSAS NORTHEASTWARD TO SOUTHEASTERN MICHIGAN. THE RELATIVE WETNESS FAVORED IN WESTERN AND NORTHERN ALASKA IS SUPPORTED PRIMARILY BY THE LAST 9 RUNS OF THE CFS, AND TO A LESSER EXTENT, THE CA-SST. THE FAVORED ABOVE NORMAL PRECIPITATION FROM THE NORTHERN ROCKIES EASTWARD TO MINNESOTA, AND FROM NORTHEASTERN ARKANSAS NORTHEASTWARD TO SOUTHEASTERN MICHIGAN IS SUPPORTED TO VARIOUS DEGREES BY THE CAS TOOL, THE NMME (ESPECIALLY UNCALIBRATED VERSION), CFS, CA-SST (OHIO VALLEY AREA), AND OBSERVED SOIL MOISTURE ANOMALIES FOR THE PAST 30-DAYS FOR MOST OF THESE AREAS. ODDS ARE TILTED TOWARDS BELOW NORMAL PRECIPITATION ACROSS SOUTHEASTERN MAINLAND ALASKA AND THE PANHANDLE REGION, MOST OF CALIFORNIA AND NEVADA, SOUTHWESTERN UTAH, ARIZONA, MOST OF NEW MEXICO, AND APPROXIMATELY THE SOUTHWESTERN HALF OF TEXAS. ODDS OF BELOW NORMAL PRECIPITATION ARE ALSO ELEVATED OVER MUCH OF THE SOUTHERN ATLANTIC COAST REGION. SUPPORT FOR THESE REGIONS OF ANTICIPATED BELOW NORMAL PRECIPITATION COMES FROM THE NMME, CFS, CA-SST (ALASKA COAST ONLY), APRIL CLIMATOLOGY, AND RECENT SOIL MOISTURE CONDITIONS (CONUS). THE HIGHEST CHANCES (IN EXCESS OF 50 PERCENT) FOR THE PRECIPITATION OUTLOOK ARE DEPICTED OVER CENTRAL AND SOUTHERN FLORIDA (FOR BELOW NORMAL PRECIPITATION), IN PART DUE TO APRIL BEING THE PEAK OF THE CLIMATOLOGICAL DRY SEASON FOR THIS AREA. 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 APR WILL BE ISSUED ON SAT MARCH 31 2018 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD. $$ OPCN-40013