549  
FXUS06 KWBC 182043  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EST THU JANUARY 18 2018  
 
6-10 DAY OUTLOOK FOR JAN 24 - 28 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. WEAK RIDGING IS EXPECTED FARTHER TO THE EAST OVER WESTERN CANADA AND TO  
THE SOUTH OFF THE COAST OF CALIFORNIA. A BROAD TROUGH IS PREDICTED OVER THE  
WEST-CENTRAL CONUS. HOWEVER, MODELS DISAGREE ON THE STRENGTH OF THIS TROUGH.  
TODAY'S 0Z ECMWF ENSEMBLE MEAN PREDICTS A DEEPER TROUGH IN THE WEST, WHILE THE  
LATEST GEFS ENSEMBLE MEANS PREDICT A WEAKER TROUGH, WITH BARELY NEGATIVE HEIGHT  
ANOMALIES. TELECONNECTIONS OFF OF THE STRONGEST ANOMALY CENTER IN THE FORECAST  
DOMAIN, THE POSITIVE HEIGHT ANOMALY CENTER OVER THE ALEUTIANS, SUPPORT RIDGING  
OVER THE SOUTHWEST, IN AGREEMENT WITH THE GEFS. THEREFORE TODAY'S MANUAL  
500-HPA BLEND FAVORS THE 6Z GEFS ENSEMBLE MEAN, WITH A WEAKER TROUGH PREDICTED  
IN THE WESTERN CONUS.  
 
THE TROUGH OVER MAINLAND ALASKA LEADS TO LARGELY ENHANCED PROBABILITIES OF  
BELOW NORMAL TEMPERATURES ACROSS ALASKA. BELOW NORMAL TEMPERATURES ARE ALSO  
FAVORED ACROSS MUCH OF THE NORTHWEST CONUS AND INTO THE NORTHERN PLAINS  
UNDERNEATH 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 99% OF TODAY'S 6Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 8, AND 1% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN  
CENTERED ON DAY 8  
 
 
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 26 - FEB 01, 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 A TROUGH IS FORECAST  
OVER PARTS OF THE CENTRAL CONUS. A RIDGE IS EXPECTED OVER THE CARIBBEAN  
EXTENDING TO PARTS OF THE SOUTHEASTERN CONUS.  
 
THE TEMPERATURE PROBABILITY FORECAST FOR THE 6-10 DAY PERIOD IS VERY SIMILAR TO  
THE WEEK-2 PERIOD. DUE TO INCREASED UNCERTAINTY OVER ALASKA AND THE WESTERN  
CONUS, PROBABILITIES ARE LOWER, WHILE OVER THE EASTERN U.S. AN INCREASE IN THE  
AMPLITUDE OF THE POSITIVE HEIGHT ANOMALIES THERE SUPPORT HIGHER FORECAST  
PROBABILITIES.  
 
THE PRECIPITATION PROBABILITY FORECAST FOR THE 6-10 DAY PERIOD IS ALSO SIMILAR  
TO THE WEEK-2 PERIOD. A STRONGER LOW LEVEL FLOW FROM THE GULF OF MEXICO  
INCREASES PROBABILITIES OF ABOVE NORMAL PRECIPITATION IN PARTS OF THE EASTERN  
U.S., AND SLIGHTLY MORE RIDGING IN THE WESTERN CONUS LEADS TO LOWER  
PROBABILITIES OF ABOVE NORMAL PRECIPITATION FOR THE PACIFIC NORTHWEST.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 50% OF TODAY'S  
OPERATIONAL 6Z GFS CENTERED ON DAY 11, AND 50% OF TODAY'S 0Z EUROPEAN ENSEMBLE  
MEAN CENTERED ON DAY 11  
 
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: MIKE C  
 
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  
FEBRUARY 15.  
 
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 - 20060104 - 20030104 - 19860124 - 19950120  
 
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 - 20060103 - 19950119 - 19810123 - 19860124  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 24 - 28 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B N  
SRN CALIF N B IDAHO B A NEVADA B A  
W MONTANA B A E MONTANA B A WYOMING B A  
UTAH B B ARIZONA N B COLORADO B B  
NEW MEXICO N B N DAKOTA B A S DAKOTA B A  
NEBRASKA B N KANSAS N B OKLAHOMA A N  
N TEXAS N A S TEXAS N A W TEXAS N B  
MINNESOTA N A IOWA A A MISSOURI A A  
ARKANSAS A A LOUISIANA A A WISCONSIN A 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 A 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 A  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 26 - FEB 01, 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B N NRN CALIF B B  
SRN CALIF N B IDAHO B A NEVADA B B  
W MONTANA B A E MONTANA B A WYOMING B A  
UTAH B B ARIZONA N B COLORADO N N  
NEW MEXICO N B N DAKOTA B A S DAKOTA N A  
NEBRASKA N A KANSAS A A OKLAHOMA A A  
N TEXAS A A S TEXAS N A W TEXAS A B  
MINNESOTA N A IOWA A A MISSOURI A A  
ARKANSAS A A LOUISIANA A A WISCONSIN A 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 A AK N SLOPE B B  
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  
 
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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