30 Day Narrative

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.
$$