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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