056  
FXUS06 KWBC 172001  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EST WED JANUARY 17 2018  
 
6-10 DAY OUTLOOK FOR JAN 23 - 27 2018  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN FAIRLY GOOD AGREEMENT ON THE EXPECTED  
500-HPA FLOW PATTERN OVER THE FORECAST DOMAIN. ALL OF TODAY'S MODEL SOLUTIONS  
FORECAST A RIDGE OVER THE WESTERN ALEUTIANS AND TROUGH OVER MUCH OF MAINLAND  
ALASKA. RIDGING IS EXPECTED FARTHER TO THE EAST OVER WESTERN CANADA AND TO THE  
SOUTH WELL OFF THE COAST OF CALIFORNIA. A BROAD TROUGH IS PREDICTED BY MOST  
SOLUTIONS OVER THE WEST-CENTRAL CONUS. HOWEVER, THE DETERMINISTIC 0Z AND 6Z GFS  
PROGRESS THIS TROUGH FARTHER TO THE EAST OVER THE CENTRAL CONUS. RIDGING IS  
LIKELY OVER THE CARIBBEAN EXTENDING TO PARTS OF THE SOUTHEASTERN CONUS.  
ENSEMBLE SPREAD IS RELATIVELY LOW OVER THE EASTERN CONUS BUT MODERATE FOR THE  
WESTERN CONUS AND ALASKA. TODAY'S MANUAL 500-HPA BLEND IS BASED PRIMARILY ON  
THE ENSEMBLE MEANS FROM THE CANADIAN, EUROPEAN, AND GEFS MODEL SUITES. THE  
RESULTANT MANUAL BLEND DEPICTS BELOW NORMAL HEIGHTS OVER MOST OF MAINLAND  
ALASKA, THE ALASKA PANHANDLE, AND MOST OF THE NORTHWESTERN AND WEST-CENTRAL  
CONUS. ABOVE NORMAL HEIGHTS ARE EXPECTED FOR MUCH OF THE EASTERN THIRD OF THE  
CONUS, THE ALEUTIANS, EXTREME WESTERN MAINLAND ALASKA, AND PARTS OF CALIFORNIA.  
 
THE TROUGH OVER MAINLAND ALASKA LEADS TO ENHANCED PROBABILITIES OF BELOW NORMAL  
TEMPERATURES ACROSS ALASKA. BELOW NORMAL TEMPERATURES ARE ALSO FAVORED ACROSS  
MUCH OF THE WESTERN CONUS AND THE NORTHERN PLAINS UNDERNEATH CYCLONIC FLOW AND  
NEAR TO BELOW NORMAL HEIGHTS. RIDGING AND ABOVE NORMAL HEIGHTS TO THE EAST OF  
THIS TROUGH FAVOR ABOVE NORMAL TEMPERATURES FOR MUCH OF THE EASTERN CONUS.  
 
THE POTENTIAL FOR SHORTWAVE TROUGHS TO MOVE INTO THE WESTERN CONUS FROM THE  
PACIFIC LEADS TO ENHANCED PROBABILITIES OF ABOVE NORMAL PRECIPITATION ACROSS  
MUCH OF THE NORTHWESTERN CONUS EXTENDING EASTWARD TO THE NORTHERN AND CENTRAL  
ROCKIES. MOIST FLOW AHEAD OF THE LONGWAVE TROUGH OVER THE WEST-CENTRAL CONUS  
FAVORS ABOVE NORMAL PRECIPITATION FOR MUCH OF THE EASTERN CONUS. BELOW NORMAL  
PRECIPITATION IS LIKELY FOR MUCH OF WESTERN AND CENTRAL ALASKA UNDERNEATH  
NORTHEASTERLY LOW LEVEL FLOW. BELOW NORMAL PRECIPITATION IS FAVORED FOR PARTS  
OF THE SOUTHWESTERN CONUS CONSISTENT WITH DYNAMICAL MODEL GUIDANCE FROM THE  
GEFS AND ECMWF ENSEMBLES AS WELL AS ANALOGS FROM THE MANUAL BLEND.  
 
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 15% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 8, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 8, 5% OF TODAY'S OPERATIONAL 0Z GFS CENTERED ON DAY 8, 25% OF TODAY'S 0Z  
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF YESTERDAY'S 12Z EUROPEAN  
ENSEMBLE MEAN CENTERED ON DAY 7, 10% OF TODAY'S OPERATIONAL 0Z ECMWF CENTERED  
ON DAY 8, 20% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8, AND 5% OF  
YESTERDAY'S 12Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 7  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO FAIRLY  
GOOD AGREEMENT AMONG THE ENSEMBLE MEAN SOLUTIONS OFFSET BY POOR AGREEMENT AMONG  
THE TELECONNECTIONS FROM THE VARIOUS HEIGHT ANOMALY CENTERS DEPICTED IN THE  
MANUAL 500-HPA HEIGHT BLEND.  
 
8-14 DAY OUTLOOK FOR JAN 25 - 31 2018  
 
DURING THE WEEK-2 PERIOD, TODAY'S MODELS DEPICT INCREASED 500-HPA SPREAD AND  
UNCERTAINTY ACROSS MUCH OF THE FORECAST DOMAIN. A MEAN TROUGH IS FORECAST TO  
PERSIST OVER MUCH OF MAINLAND ALASKA WITH RIDGES PREDICTED ON EITHER SIDE OF  
THIS FEATURE OVER THE ALEUTIANS AND WESTERN CANADA. FARTHER TO THE SOUTH,  
RIDGING IS FORECAST OFF THE WEST COAST OF THE CONUS WHILE SHALLOW, CYCLONIC  
FLOW IS DEPICTED FROM THE GREAT LAKES SOUTHWESTWARD TO THE SOUTHWESTERN CONUS.  
A RIDGE IS EXPECTED OVER THE CARIBBEAN EXTENDING TO PARTS OF THE SOUTHEASTERN  
CONUS. ENSEMBLE SPREAD IS RELATIVELY HIGH OVER THE WESTERN CONUS AND SUCCESSIVE  
RUNS OF THE DETERMINISTIC GFS VARY GREATLY ON THE POSITION OF A LONGWAVE TROUGH  
OVER THE CONUS. DUE TO THESE UNCERTAINTIES, THE MANUAL 500-HPA HEIGHT BLEND IS  
BASED ALMOST ENTIRELY ON THE ENSEMBLE MEAN SOLUTIONS. ABOVE NORMAL HEIGHTS ARE  
EXPECTED FOR THE EASTERN THIRD OF THE CONUS, THE ALEUTIANS, EXTREME WESTERN  
MAINLAND ALASKA, AND MUCH OF CALIFORNIA. BELOW NORMAL HEIGHTS ARE FORECAST FOR  
SOUTHEASTERN MAINLAND ALASKA AND THE ALASKA PANHANDLE.  
 
THE TROUGH OVER ALASKA LEADS TO ENHANCED PROBABILITIES OF BELOW NORMAL  
TEMPERATURES ACROSS THE STATE. ABOVE NORMAL HEIGHTS ENHANCE PROBABILITIES OF  
ABOVE NORMAL TEMPERATURES ACROSS MUCH OF THE EASTERN CONUS. BELOW NORMAL  
TEMPERATURES ARE FAVORED FOR MUCH OF THE NORTHWESTERN CONUS UNDERNEATH NEAR TO  
BELOW NORMAL HEIGHTS. PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE SLIGHTLY  
ELEVATED FOR PARTS OF THE SOUTHWESTERN CONUS IN ASSOCIATION WITH ABOVE NORMAL  
HEIGHTS.  
 
MOIST FLOW AHEAD OF A TROUGH OVER THE CENTRAL CONUS INCREASES PROBABILITIES OF  
ABOVE NORMAL PRECIPITATION OVER MUCH OF THE EASTERN HALF OF THE CONUS. ABOVE  
NORMAL PRECIPITATION IS ALSO FAVORED FOR THE NORTHWESTERN CONUS AND PARTS OF  
THE ALASKA PANHANDLE DUE TO THE POTENTIAL FOR ENHANCED PACIFIC FLOW. DYNAMICAL  
MODEL GUIDANCE FROM THE ECMWF AND GEFS ENSEMBLE MEMBERS FAVOR BELOW NORMAL  
PRECIPITATION FOR PARTS OF THE SOUTHWESTERN CONUS. BELOW NORMAL PRECIPITATION  
IS ALSO FAVORED FOR PARTS OF WESTERN MAINLAND ALASKA UNDERNEATH MEAN  
NORTHEASTERLY LOW LEVEL FLOW.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 20% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 11, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 11, 5% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON DAY 11, 30% OF TODAY'S  
0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 5% OF YESTERDAY'S 12Z EUROPEAN  
ENSEMBLE MEAN CENTERED ON DAY 10, 20% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN  
CENTERED ON DAY 11, AND 5% OF YESTERDAY'S 12Z CANADIAN ENSEMBLE MEAN CENTERED  
ON DAY 10  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO  
RELATIVELY HIGH MODEL SPREAD AND POOR AGREEMENT AMONG THE SURFACE TOOLS.  
 
FORECASTER: SCOTT H  
 
NOTES:  
 
AUTOMATED FORECASTS ARE ISSUED ON SATURDAY AND SUNDAY. OCCASIONALLY MANUAL  
INTERVENTION IS NECESSARY TO ADDRESS QUALITY CONTROL AND CONSISTENCY ISSUES. IN  
THESE CASES, FORECASTS ARE MANUALLY DRAWN BUT A FULL DISCUSSION IS NOT ISSUED.  
 
THE NOTATION FOR THE CATEGORICAL FORECAST INDICATED ON THE MAPS IS THE SAME AS  
THAT IN THE TABLES: A-ABOVE N-NEAR NORMAL B-BELOW  
 
THE TEMPERATURE MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING WARMER (ORANGE,  
"A"), COLDER (BLUE, "B"), OR CLOSE TO (UNSHADED, "N"). HISTORICAL AVERAGE  
VALUES FOR THE CALENDAR PERIOD OF THE FORECAST (DASHES, "F"). LABELS ON THE  
SHADED LINES GIVE THE PROBABILITY (> 33%) OF THE MORE LIKELY CATEGORY (B OR A).  
PROBABILITY OF N IS ALWAYS < 40%.  
 
THE PRECIPITATION MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING WETTER (GREEN,  
"A"), DRIER (TAN, "B"), OR CLOSE TO (UNSHADED, "N"). HISTORICAL MEDIAN VALUES  
FOR THE CALENDAR PERIOD OF THE FORECAST (DASHES, "INCHES"). LABELS ON THE  
SHADED LINES GIVE THE PROBABILITY (> 33%) OF THE MORE LIKELY CATEGORY (B OR A).  
PROBABILITY OF N IS ALWAYS < 40%.  
 
IN THE SOUTHWEST AND OTHER CLIMATOLOGICALLY DRY REGIONS - THERE WILL BE A  
GREATER THAN 33.3% CHANCE OF NO PRECIPITATION AND OCCASIONALLY EVEN A NORMAL  
(I.E. MEDIAN) VALUE OF ZERO - ESPECIALLY DURING THE DRY SEASONS. IN SUCH CASES  
A FORECAST OF NEAR NORMAL IS EFFECTIVELY A FORECAST OF LITTLE OR NO  
PRECIPITATION.  
 
THE CLIMATE PREDICTION CENTER USES 1981-2010 BASE PERIOD MEANS FOR  
TEMPERATURE...PRECIPITATION...AND 500-HPA HEIGHTS AS REFERENCE IN THE CLIMATE  
OUTLOOKS.  
 
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON  
JANUARY 18.  
 
ANALOGS TO THE 5 DAY MEAN OBSERVED PATTERN CENTERED 3 DAYS AGO (D-3)  
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE  
INCLUDE THE 5 DAY PERIODS CENTERED ON THE FOLLOWING DATES:  
20010120 - 19860124 - 20030104 - 20060104 - 19980125  
 
ANALOGS TO THE 7 DAY MEAN OBSERVED PATTERN CENTERED 4 DAYS AGO (D-4)  
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE  
INCLUDE THE 7 DAY PERIODS CENTERED ON THE FOLLOWING DATES:  
20010120 - 19950119 - 19941229 - 19810123 - 20060102  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 23 - 27 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B A  
SRN CALIF N B IDAHO B A NEVADA B A  
W MONTANA B A E MONTANA B A WYOMING B A  
UTAH B A ARIZONA N B COLORADO B N  
NEW MEXICO N B N DAKOTA B A S DAKOTA B A  
NEBRASKA B A KANSAS N N OKLAHOMA N N  
N TEXAS N A S TEXAS N A W TEXAS N N  
MINNESOTA N A IOWA N A MISSOURI N A  
ARKANSAS A A LOUISIANA A A WISCONSIN N A  
ILLINOIS A A MISSISSIPPI A A MICHIGAN N A  
INDIANA A A OHIO A A KENTUCKY A A  
TENNESSEE A A ALABAMA A A NEW YORK A A  
VERMONT A A NEW HAMP A A MAINE A A  
MASS A A CONN A A RHODE IS A A  
PENN A A NEW JERSEY A A W VIRGINIA A A  
MARYLAND A A DELAWARE A A VIRGINIA A A  
N CAROLINA A A S CAROLINA A A GEORGIA A A  
FL PNHDL A N FL PENIN A N AK N SLOPE B N  
AK ALEUTIAN B B AK WESTERN B B AK INT BSN B B  
AK S INT B B AK SO COAST B B AK PNHDL B N  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 25 - 31 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF N B  
SRN CALIF N B IDAHO B A NEVADA N B  
W MONTANA B A E MONTANA B A WYOMING B N  
UTAH N N ARIZONA N B COLORADO N N  
NEW MEXICO N N N DAKOTA N N S DAKOTA N A  
NEBRASKA N N KANSAS N N OKLAHOMA N A  
N TEXAS N A S TEXAS N A W TEXAS N N  
MINNESOTA N A IOWA A A MISSOURI A A  
ARKANSAS A A LOUISIANA A A WISCONSIN N A  
ILLINOIS A A MISSISSIPPI A A MICHIGAN A A  
INDIANA A A OHIO A A KENTUCKY A A  
TENNESSEE A A ALABAMA A A NEW YORK A A  
VERMONT A A NEW HAMP A A MAINE A A  
MASS A A CONN A A RHODE IS A A  
PENN A A NEW JERSEY A A W VIRGINIA A A  
MARYLAND A A DELAWARE A A VIRGINIA A A  
N CAROLINA A A S CAROLINA A A GEORGIA A A  
FL PNHDL A A FL PENIN A N AK N SLOPE B N  
AK ALEUTIAN B N AK WESTERN B B AK INT BSN B N  
AK S INT B N AK SO COAST B N AK PNHDL B A  
 
LEGEND  
TEMPS WITH RESPECT TO NORMAL PCPN WITH RESPECT TO MEDIAN  
A - ABOVE N - NEAR NORMAL A - ABOVE N - NEAR MEDIAN  
B - BELOW B - BELOW  
 
THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL  
VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE  
AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE.  
 
FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 KWBC - ON AWIPS AS  
PMDMRD.  
 

 
 
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