PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
830 AM EST THU FEB 15 2018


30-DAY OUTLOOK DISCUSSION FOR MARCH 2018

LA NINA CONDITIONS CONTINUE INTO MID-FEBRUARY, WITH NEGATIVE SST ANOMALIES 
OBSERVED ACROSS THE CENTRAL AND EASTERN PACIFIC OCEAN FROM NEAR THE DATE LINE 
TO THE COAST OF SOUTH AMERICA. THE COUPLED ATMOSPHERIC RESPONSE TO LA NINA 
REMAINS READILY OBSERVED, WITH POSITIVE OLR ANOMALIES DUE TO REDUCED CONVECTION 
NEAR THE DATE LINE AND NEGATIVE OLR ANOMALIES DUE TO ENHANCED CONVECTION OVER 
PARTS OF THE MARITIME CONTINENT. THE MJO REMAINED ACTIVE OVER THE PAST SEVERAL 
WEEKS; THE ENHANCED PHASE PROPAGATED ACROSS THE WEST PACIFIC OF LATE AND 
EASTWARD PROPAGATION HAS SLOWED. THE CURRENT MJO STATE FAVORS BELOW-NORMAL 
TEMPERATURES OVER MUCH OF THE CONUS IN EARLY MARCH. ADDITIONALLY, A SUDDEN 
STRATOSPHERIC WARMING OCCURRED ON FEBRUARY 12. EMPIRICALLY, THIS FAVORS A 
MODEST SHIFT IN THE LOW-FREQUENCY AO TOWARD THE NEGATIVE PHASE. THE RECENT RUNS 
OF THE GEFS AND CFS FORECAST A TRANSITIONS TOWARD A STRONGLY NEGATIVE AO 
REGIME, WITH HIGH-LATITUDE BLOCKING FORECAST NEAR THE DAVIS STRAIT. THE ECWMF 
SHOWS A SIMILAR EVOLUTION, BUT WITHOUT THE ASSOCIATED TELECONNECTION PATTERN 
OVER THE EASTERN CONUS. DYNAMICAL MODEL GUIDANCE INITIALIZED IN EARLY FEBRUARY 
SEEMS TO EMPHASIZE LA NINA AND LONG-TERM TRENDS, A REASONABLE STARTING PLACE 
FOR THE MARCH OUTLOOK.

THE MARCH TEMPERATURE OUTLOOK STARTS WITH THE CALIBRATED DYNAMICAL MODEL 
GUIDANCE, BUT MAKES RATHER SUBSTANTIAL CHANGES BASED ON THE LATEST CFS 
FORECASTS AND EMPIRICAL FORECAST MODELS THAT ARE CONSISTENT WITH A STRONG 
NEGATIVE AO PROJECTION DURING THE EARLY PART OF THE MONTH. ANY MJO IMPACTS 
DURING THE SECOND HALF OF THE MONTH ARE A BIT OF A WILD CARD GIVEN UNCERTAINTY 
IN MJO EVOLUTION DURING LATE FEBRUARY AND EARLY MARCH.

THE MARCH TEMPERATURE OUTLOOK INDICATES INCREASES IN THE PROBABILITIES OF 
BELOW-NORMAL TEMPERATURES OVER MUCH OF THE NORTHWESTERN AND NORTH-CENTRAL 
CONUS, AND WITH REASONABLY LARGE PROBABILITIES FOR A 0.5-MONTH LEAD OUTLOOK. 
THIS SIGNAL IS CONSISTENT WITH LA NINA, EARLY MONTH MJO IMPACTS, AND A 
COMBINATION OF DYNAMICAL MODEL GUIDANCE. OVER THE FAR SOUTHERN AND EASTERN 
PARTS OF THE CONUS, ABOVE-NORMAL TEMPERATURES ARE FAVORED. THE SIGNAL IS 
STRONGEST OVER NEW ENGLAND WHERE THE LATEST MODEL GUIDANCE SUGGESTS THE HIGHEST 
PROBABILITIES. THIS IS ALSO CONSISTENT WITH TELECONNECTIONS UPON A BLOCKING 
PATTERN OVER DAVIS STRAIT. LONG-TRENDS AND LA NINA FAVOR ABOVE-NORMAL 
TEMPERATURES OVER THE SOUTHWEST, BUT THIS IS TEMPERED BY THE LATEST DYNAMICAL 
MODEL GUIDANCE THAT SUGGESTS A RELATIVELY COLD START TO THE MONTH. EQUAL 
CHANCES OF ABOVE-, NEAR-, AND BELOW-NORMAL TEMPERATURES IS FORECAST OVER A 
LARGE SWATH OF THE CONUS FROM THE SOUTH-CENTRAL U.S. EASTWARD. OVER THIS REGION 
THERE ARE CONFLICTING SIGNALS BETWEEN THE LOW-FREQUENCY TRENDS AND ENSO AND 
HIGHER-FREQUENCY AO AND MJO CONTRIBUTIONS. ABOVE-NORMAL TEMPERATURES ARE 
FAVORED OVER WESTERN ALASKA WHERE THE MAJORITY OF FORECAST TOOLS ARE IN GOOD 
AGREEMENT.

THE MARCH PRECIPITATION OUTLOOK, LIKE THE TEMPERATURE OUTLOOK, ATTEMPTS TO 
COMBINE THE INFLUENCE OF LA NINA WITH THE LATEST CFS GUIDANCE AND THE AO AND 
MJO FOOTPRINTS EARLY IN THE MONTH. ABOVE-NORMAL PRECIPITATION IS FAVORED OVER 
THE NORTHERN ROCKIES, AND EXTENDED EASTWARD INTO PARTS OF THE CENTRAL AND 
NORTHERN HIGH PLAINS. ABOVE-NORMAL PRECIPITATION IS ALSO FAVORED OVER PARTS OF 
THE INTERIOR SOUTHEAST; THIS REGION IS SHIFTED SOUTHEAST OF THE CANONICAL LA 
NINA FOOTPRINT BASED ON THE MJO AND AO. BELOW-NORMAL PRECIPITATION IS FAVORED 
ACROSS THE SOUTHERN TIER OF THE CONUS EXCEPT FOR MUCH OF THE GULF COAST. THIS 
IS BROADLY CONSISTENT WITH LA NINA AND BASED ON THE PREPONDERANCE OF DYNAMICAL 
MODEL GUIDANCE. EQUAL CHANCES IS FORECAST FOR LARGE SECTIONS OF THE CENTRAL AND 
EASTERN CONUS WHERE THE VARIOUS AFOREMENTIONED CLIMATE SIGNALS CONFLICT, AS 
DOES THE LATEST CFS WITH COUPLED MODEL INITIALIZED AT THE BEGINNING OF THE 
MONTH. ANOMALOUS RIDGING CENTERED JUST SOUTH OF ALASKA FAVORS A NORTHWARD 
SHIFTED STORM TRACK, AND THUS A NORTH-SOUTH DIPOLE IN PROBABILITIES FAVORING 
ABOVE- AND BELOW-NORMAL PRECIPITATION.

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.

AN UPDATED MONTHLY OUTLOOK... FOR MAR WILL BE ISSUED ON WED FEBRUARY 28 2018

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