369  
FXUS07 KWBC 312000  
PMD30D  
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST WED JAN 31 2018  
 
30-DAY OUTLOOK DISCUSSION FOR FEBRUARY 2018  
 
THE MONTHLY UPDATE TO THE FEBRUARY 2018 OUTLOOK IS BASED PRIMARILY ON THE  
LATEST DYNAMICAL MODEL GUIDANCE FOR THE MONTH FROM THE NCEP CLIMATE FORECAST  
SYSTEM (CFS), WEATHER FORECASTS FOR THE FIRST WEEK OF FEBRUARY, AS WELL AS  
TEMPERATURE AND PRECIPITATION GUIDANCE FOR THE OUTLOOKS FOR WEEK 2 AND FOR THE  
WEEK 3-4 PERIOD. THE MADDEN-JULIAN OSCILLATION OR MJO HAS BEEN ACTIVE RECENTLY  
WITH ENHANCED CONVECTION CURRENTLY MOVING FROM THE MARITIME CONTINENT INTO THE  
WESTERN PACIFIC. DYNAMICAL MODEL FORECASTS INDICATE THAT THE ENHANCED  
CONVECTIVE PHASE OF THE MJO IS LIKELY TO PROPAGATE ACROSS THE WESTERN PACIFIC  
IN THE FIRST COUPLE WEEKS OF FEBRUARY. LA NINA CONDITIONS CONTINUE IN LATE  
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 THE MARITIME CONTINENT. ENHANCED EASTERLIES WERE OBSERVED OVER  
THE WESTERN AND CENTRAL TROPICAL PACIFIC OCEAN.  
 
BASED ON RECENT DYNAMICAL MODEL GUIDANCE, A STRONG RIDGE IS EXPECTED TO DEVELOP  
OVER WESTERN NORTH AMERICA DURING THE FIRST TWO WEEKS OF THE MONTH. A TROUGH IS  
PREDICTED DOWNSTREAM OF THIS RIDGE OVER CENTRAL NORTH AMERICA IN GUIDANCE FOR  
THE OUTLOOK FOR WEEKS 1 AND 2. THIS CIRCULATION PATTERN IS PREDICTED TO BRING  
BELOW NORMAL TEMPERATURES FOR THE NORTHERN CENTRAL CONUS AND MUCH OF THE  
EASTERN CONUS FROM THE CENTRAL MISSISSIPPI VALLEY, ACROSS THE OHIO VALLEY TO  
THE CHESAPEAKE BAY, AS WELL AS ACROSS THE GREAT LAKES REGION AND INTO THE  
NORTHEAST. FORECASTS FOR THE FIRST HALF OF FEBRUARY LEAD TO INCREASED  
PROBABILITIES OF BELOW NORMAL AVERAGE TEMPERATURES FOR THE MONTH, WITH THE  
GREATEST PROBABILITIES OVER PARTS OF THE NORTHERN PLAINS/UPPER MISSISSIPPI  
VALLEY, WHERE TEMPERATURES ARE PREDICTED TO BE MUCH BELOW NORMAL IN THE FIRST  
WEEK OF THE MONTH. ABOVE NORMAL TEMPERATURES ARE LIKELY FOR MOST OF THE WEST,  
WHERE A RIDGE AND ABOVE AVERAGE 500-HPA HEIGHTS ARE PREDICTED TO PERSIST  
THROUGH MOST OF THE MONTH, INCLUDING GUIDANCE FROM NCEP GEFS, CFS AND ECMWF  
MODELS. ABOVE NORMAL TEMPERATURES CONTINUE TO BE MOST LIKELY FOR THE GULF COAST  
REGION AND SOUTHEAST, HOWEVER PROBABILITIES HAVE BEEN REDUCED IN THE MONTHLY  
UPDATE DUE TO THE INCREASED PROBABILITIES OF BELOW NORMAL EARLY IN THE MONTH.  
DYNAMICAL MODELS INDICATE BELOW NORMAL TEMPERATURES ARE MOST LIKELY OVER  
SOUTHEASTERN ALASKA DURING THE FIRST WEEK OF FEBRUARY, HOWEVER BY WEEK 2  
TEMPERATURES ARE PREDICTED TO BE ABOVE NORMAL IN THIS REGION. THE GREATER SKILL  
OF FORECASTS FOR SHORTER LEAD TIMES LEADS TO INCREASED PROBABILITIES FOR BELOW  
NORMAL AVERAGE TEMPERATURES FOR THE MONTH OVER SOUTHEASTERN ALASKA AND THE  
ALASKA PANHANDLE. ABOVE NORMAL TEMPERATURES CONTINUE TO BE MOST LIKELY FOR  
WESTERN AND NORTHERN ALASKA FOR THE MONTH OF FEBRUARY AS INDICATED BY MODEL  
GUIDANCE FROM THE CFS.  
 
THE UPDATE TO THE FEBRUARY PRECIPITATION OUTLOOK INDICATES CHANGES RELATED TO  
DYNAMICAL MODEL GUIDANCE, WHERE GREATER WEIGHT IS GIVEN TO FORECASTS FOR THE  
FIRST TWO WEEKS, GIVEN THE DROP IN SKILL OF PRECIPITATION FORECASTS WITH  
GREATER LEAD TIME. ABOVE MEDIAN PRECIPITATION IS MOST LIKELY FOR MUCH OF THE  
EASTERN CONUS DURING THE FIRST WEEK OF THE MONTH, FROM THE CENTRAL GULF COAST  
TO THE NORTHEAST. BELOW MEDIAN PRECIPITATION IS MOST LIKELY FOR MUCH OF THE  
WESTERN CONUS AND SOUTHERN PLAINS DURING THE EARLY PART OF THE MONTH. THESE  
FORECASTS FOR THE FIRST HALF OF THE MONTH ARE BLENDED WITH THE HALF-MONTH LEAD  
PRECIPITATION OUTLOOK, WHICH INDICATES THE AVERAGE IMPACTS OF LA NINA FOR  
FEBRUARY. THE UPDATE TO THE FEBRUARY PRECIPITATION OUTLOOK INDICATES INCREASED  
PROBABILITIES OF BELOW MEDIAN PRECIPITATION FOR MUCH OF THE WEST, FROM SOUTHERN  
OREGON ACROSS NEVADA INTO THE SOUTHWEST, AS INDICATED BY RECENT MODEL GUIDANCE.  
PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR THE SOUTHEAST HAVE DECREASED  
FROM THE PRIOR OUTLOOK, WITH ABOVE MEDIAN PRECIPITATION MORE LIKELY EARLY IN  
THE MONTH. PROBABILITIES OF ABOVE MEDIAN PRECIPITATION ARE INCREASED FOR THE  
NORTHERN PLAINS FROM EASTERN MONTANA TO MINNESOTA, AND REDUCED FOR AREAS OF THE  
NORTHERN ROCKIES, FOLLOWING MODEL FORECASTS FOR WEEKS 1 AND 2. INCREASED  
PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION CONTINUE FOR THE NORTHEAST,  
EXTENDING FURTHER SOUTH ALONG THE ATLANTIC COAST. THE FEBRUARY PRECIPITATION  
OUTLOOK FOR ALASKA IS SIMILAR TO THE HALF-MONTH LEAD OUTLOOK, WITH AN INCREASE  
IN THE PROBABILITIES OF ABOVE MEDIAN PRECIPITATION FOR THE ALASKA PANHANDLE.  
 
THE PRIOR FORECAST DISCUSSION FOR THE HALF-MONTH LEAD FEBRUARY OUTLOOK ISSUED  
JANUARY 18 IS BELOW.  
 
_____  
 
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.  
 
THE NEXT MONTHLY OUTLOOK...FOR MAR ... WILL BE ISSUED ON THU FEB 15 2018  
 
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD.  

 
 
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