807  
FXUS07 KWBC 181331  
PMD30D  
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
830 AM EST THU JAN 18 2018  
 
30-DAY OUTLOOK DISCUSSION FOR FEBRUARY 2018  
 
LA NINA CONDITIONS CONTINUED INTO MID-JANUARY, WITH NEGATIVE SEA SURFACE  
TEMPERATURE (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 WAS OBSERVED AS WELL, WITH POSITIVE OUTGOING  
LONGWAVE RADIATION (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 LOW-LEVEL EASTERLIES OBSERVED AT THE 850-HPA LEVEL WERE  
ENHANCED OVER THE WESTERN PACIFIC. LA NINA IS EXPECTED TO IMPACT THE  
TEMPERATURE AND PRECIPITATION PATTERNS IN FEBRUARY OVER NORTH AMERICA. TROPICAL  
CONDITIONS PROJECT ONTO THE MADDEN-JULIAN OSCILLATION (MJO) PHASE 4, WITH  
ENHANCED CONVECTION OVER THE MARITIME CONTINENT. DYNAMICAL MODELS PREDICT  
PROPAGATION OF THE ACTIVE MJO INTO THE WESTERN PACIFIC IN EARLY FEBRUARY. A  
PREDICTED ACTIVE MJO, WITH THE ONGOING LA NINA BASE STATE, COULD IMPACT CLIMATE  
VARIABILITY IN FEBRUARY, INCREASING THE UNCERTAINTY IN THE AVERAGE FEBRUARY  
FORECAST. THE CURRENT MJO PHASE AND FORECAST INCREASE THE LIKELIHOOD OF ABOVE  
NORMAL TEMPERATURES OVER THE EASTERN CONUS AND BELOW NORMAL TEMPERATURES IN THE  
NORTHWEST EARLY IN THE MONTH.  
 
THE FEBRUARY TEMPERATURE OUTLOOK RELIES PRIMARILY ON CALIBRATED PROBABILITIES  
OF ABOVE AND BELOW NORMAL TEMPERATURES FROM THE NORTH AMERICAN MULTI-MODEL  
ENSEMBLE (NMME), WITH CONSIDERATION OF THE IMPACTS OF AN ONGOING LA NINA, AS  
EXPRESSED THROUGH BRIDGING OF PREDICTED NINO 3.4 REGION SST ANOMALIES AND  
CALIBRATED TEMPERATURE PROBABILITIES, USING STATISTICAL FORECASTS OF ENSO  
IMPACTS. ADDITIONAL CONSIDERATION WAS GIVEN TO DYNAMICAL MODEL FORECASTS FOR  
THE BEGINNING OF FEBRUARY THAT ARE IMPACTED BY AN ACTIVE MJO.  
 
THE FEBRUARY TEMPERATURE OUTLOOK INDICATES INCREASES IN THE PROBABILITIES OF  
ABOVE NORMAL TEMPERATURES FOR THE U.S. SOUTHWEST, NORTHWARD TO SOUTHERN  
WYOMING. INCREASED PROBABILITIES OF ABOVE NORMAL TEMPERATURES EXTEND EASTWARD  
TO THE SOUTHERN GREAT PLAINS, THE GULF COAST, AND THE SOUTHEAST REGION, AND  
EXTEND NORTHWARD ALONG THE EAST COAST TO NEW ENGLAND. PROBABILITIES ARE HIGHEST  
FOR PARTS OF THE SOUTHWEST AND SOUTHERN TEXAS AND LOUISIANA, CONSISTENT WITH  
DECADAL TEMPERATURE TRENDS AND LA NINA IMPACTS. THE LIKELIHOOD OF ABOVE NORMAL  
TEMPERATURES ARE REDUCED OVER NEW ENGLAND AND EQUAL CHANCES IS INDICATED OVER  
THE MIDWEST, AS WELL AS MUCH OF SOUTHERN CALIFORNIA AND NEVADA, WHERE  
VARIABILITY RELATED TO MJO AND LA NINA INCREASE UNCERTAINTY IN THE NMME  
PREDICTED FEBRUARY MEAN TEMPERATURES. BELOW NORMAL TEMPERATURES ARE MOST LIKELY  
FOR SOUTHEASTERN REGIONS OF ALASKA AND PARTS OF THE PACIFIC NORTHWEST, FROM  
NORTHERN CALIFORNIA INTO OREGON AND WASHINGTON, AND EASTWARD INTO MONTANA,  
ASSOCIATED WITH PREDICTED TEMPERATURE PROBABILITIES FOR EARLY FEBRUARY  
RESULTING LARGELY FROM THE COMBINED IMPACTS OF LA NINA AND THE MJO. ABOVE  
NORMAL TEMPERATURES ARE MOST LIKELY FOR WESTERN AND NORTHERN ALASKA, AS  
INDICATED BY NMME DYNAMICAL MODEL FORECASTS AND DECADAL TRENDS.  
 
THE FEBRUARY PRECIPITATION OUTLOOK, RELYING PRIMARILY ON THE  
PROBABILITY-ANOMALY-CORRELATION CALIBRATED PROBABILITIES FROM THE NMME,  
RESEMBLES THE CANONICAL IMPACTS DUE TO LA NINA, WITH GREATER UNCERTAINTY  
RELATED TO ADDITIONAL CLIMATE FORCING SUCH AS THE MJO. ABOVE NORMAL  
PRECIPITATION IS MOST LIKELY FOR PARTS OF THE NORTHERN ROCKY MOUNTAINS, FROM  
NORTHERN UTAH INTO EASTERN OREGON AND WASHINGTON, AS WELL AS IDAHO, MONTANA AND  
WESTERN WYOMING. MONTHLY AVERAGE PRECIPITATION IS MOST LIKELY TO BE ABOVE  
NORMAL FOR THE MIDWEST FROM THE CENTRAL AND UPPER MISSISSIPPI VALLEY INTO THE  
OHIO VALLEY AND GREAT LAKES REGION. ABOVE NORMAL PRECIPITATION IS ALSO MOST  
LIKELY TO THE EAST IN NEW ENGLAND, HOWEVER WITH GREATER UNCERTAINTY. BELOW  
NORMAL PRECIPITATION IS MOST LIKELY ACROSS THE SOUTHERN CONUS FROM NEW MEXICO  
ACROSS TEXAS AND THE GULF COAST TO THE SOUTHERN ATLANTIC COAST, FOLLOWING  
CANONICAL IMPACTS OF LA NINA AS PREDICTED BY CALIBRATED PROBABILITY FORECASTS  
FROM THE NMME. EQUAL CHANCES OF ABOVE, NEAR OR BELOW NORMAL PRECIPITATION IS  
INDICATED FOR THE WEST COAST OF THE CONUS AND WESTERN AREAS OF THE SOUTHWEST,  
WHERE UNCERTAINTY IS GREATER DUE TO VARIABILITY IN DYNAMICAL MODEL FORECASTS.  
THE INCREASED LIKELIHOOD OF BELOW NORMAL PRECIPITATION INDICATED FOR  
SOUTHEASTERN ALASKA INCLUDING THE PANHANDLE IS A CANONICAL IMPACT OF AN ONGOING  
LA NINA. ABOVE NORMAL PRECIPITATION IS MOST LIKELY FOR WESTERN AND NORTHERN  
ALASKA, AS INDICATED BY NMME FORECAST PROBABILITIES.  
 
FORECASTER: DAN COLLINS  
 
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 FEB WILL BE ISSUED ON WED JANUARY 31 2018  
 
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD.  

 
 
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