522  
FXUS06 KWBC 022046  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EST TUE JANUARY 02 2018  
 
6-10 DAY OUTLOOK FOR JAN 08 - 12 2018  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN GOOD AGREEMENT ON THE PREDICTED 500-HPA  
FLOW PATTERN OVER THE FORECAST DOMAIN. AN AMPLIFIED RIDGE IS FORECAST OVER  
ALASKA, ASSOCIATED WITH SIGNIFICANTLY POSITIVE HEIGHT ANOMALIES. THIS RIDGE IS  
FORECAST TO EXTEND SOUTH TO NEAR THE PACIFIC NORTHWEST. AN ANOMALOUS TROUGH IS  
PREDICTED OFF THE CALIFORNIA COAST. A LARGE, LONGWAVE TROUGH IS ANTICIPATED  
OVER MUCH OF THE EASTERN TWO-THIRDS OF THE CONUS. HOWEVER THERE'S A GOOD DEAL  
OF UNCERTAINTY REGARDING HOW DEEP THIS TROUGH WILL BE. OVER THE PAST COUPLE OF  
DAYS THE ENSEMBLE MEAN SOLUTIONS HAVE TRENDED TOWARDS BUILDING POSITIVE HEIGHT  
ANOMALIES IN THE EASTERN CONUS, WHILE TODAY'S DETERMINISTIC GFS AND ECMWF RUNS  
PREDICT A DEEP TROUGH AND LARGE NEGATIVE HEIGHT ANOMALIES IN THIS REGION DURING  
THE 6-10 DAY PERIOD. THE HIGHER BLEND WEIGHTS WERE GIVEN TO THE ENSEMBLE MEAN  
SOLUTIONS DUE TO SUBSTANTIALLY HIGHER 500-HPA ANOMALY CORRELATIONS IN THE PAST  
60 DAYS, FOLLOWED BY THE 0Z DETERMINISTIC ECMWF RUN, AND THEN THE 0Z AND 6Z  
DETERMINISTIC GFS RUNS. ENSEMBLE SPREAD (AT 5760 M) IS LOW TO MODERATE OVER THE  
CONUS, AND MODERATE OVER THE EASTERN PACIFIC.  
 
LARGE POSITIVE HEIGHT ANOMALIES ASSOCIATED WITH AN EXPECTED RIDGE OVER ALASKA  
STRONGLY FAVOR ABOVE NORMAL TEMPERATURES FOR MOST OF THE STATE, EXCEPT FOR  
PARTS OF SOUTHEAST MAINLAND ALASKA AND THE PANHANDLE, WHERE NORTHEASTERLY  
SURFACE FLOW IS PREDICTED TO FAVOR NEAR TO BELOW NORMAL TEMPERATURES. A RIDGE  
FORECAST IN THE WESTERN CONUS INCREASES THE LIKELIHOOD OF ABOVE NORMAL  
TEMPERATURES FOR MOST AREAS WEST OF THE CONTINENTAL DIVIDE, THE CENTRAL HIGH  
PLAINS, MOST OF THE SOUTHERN PLAINS, AND LOUISIANA. ANOMALOUSLY COLD AIR,  
SLIDING SOUTH FROM CANADA INTO THE TROUGH PREDICTED IN THE EASTERN HALF OF THE  
CONUS, ENHANCES THE CHANCES FOR BELOW NORMAL TEMPERATURES FROM THE NORTHERN  
PLAINS AND EASTERN NEBRASKA EASTWARD ACROSS THE NORTHERN HALF OF THE  
MISSISSIPPI VALLEY, THE GREAT LAKES REGION AND OHIO VALLEY, THE NORTHERN AND  
CENTRAL APPALACHIANS, AND THE ATLANTIC COAST STATES FROM MAINE TO MARYLAND AND  
NORTHERN VIRGINIA. THE TEMPERATURE OUTLOOK FOR THE 6-10 DAY PERIOD IS LARGELY  
BASED ON THE AUTOMATED TEMPERATURE FORECAST, THE GEFS AND ECMWF CALIBRATED  
REFORECAST TOOLS, AND DYNAMICAL MODEL TEMPERATURE FORECASTS.  
 
SEVERAL CYCLONIC SYSTEMS ARE FORECAST TO MOVE ACROSS THE ALEUTIANS AND INTO  
WESTERN MAINLAND ALASKA DURING THE 6-10 DAY PERIOD, FAVORING ABOVE NORMAL  
PRECIPITATION FOR THAT REGION. THE EASTERN MAINLAND OF ALASKA, AND THE  
PANHANDLE ARE EXPECTED TO BE EAST OF THE MEAN RIDGE AXIS, UNDER NORTHEASTERLY  
ANOMALOUS FLOW, WHICH FAVORS DRIER THAN NORMAL CONDITIONS. A PREDOMINANTLY WET  
PATTERN IS ANTICIPATED OVER THE CONUS, DUE TO MOISTURE STREAMING OUT AHEAD OF  
THE TROUGH NEAR THE CALIFORNIA COAST, AND ALSO ASSOCIATED WITH SHORTWAVES THAT  
ARE EXPECTED TO MOVE THROUGH THE LONGWAVE TROUGH OVER THE EAST-CENTRAL CONUS.  
THE PRECIPITATION OUTLOOK FOR THE 6-10 DAY PERIOD IS LARGELY BASED ON THE  
AUTOMATED PRECIPITATION FORECAST, THE GEFS AND ECMWF CALIBRATED REFORECAST  
TOOLS, DYNAMICAL MODEL PRECIPITATION FORECASTS, AND INSPECTION OF STORM TRACKS  
AS DEPICTED BY TODAY'S 12Z DETERMINISTIC GFS RUN.  
 
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 20% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 8, 20% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 8, 5% OF TODAY'S OPERATIONAL 0Z GFS CENTERED ON DAY 8, 5% OF TODAY'S  
OPERATIONAL 6Z GFS CENTERED ON DAY 8, 20% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN  
CENTERED ON DAY 8, 10% OF TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8, AND  
20% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
GOOD MODEL AGREEMENT AND AGREEMENT AMONG THE TOOLS, OFFSET BY SOME UNCERTAINTY  
IN THE STRENGTH OF THE EASTERN TROUGH.  
 
8-14 DAY OUTLOOK FOR JAN 10 - 16 2018  
 
BY THE WEEK-2 PERIOD, MODELS ARE IN FAIRLY GOOD AGREEMENT THAT RIDGING WILL  
CONTINUE ACROSS ALASKA, BUT WEAKEN ACROSS THE SOUTHERN PORTION OF THE STATE, AS  
A DEEPENING TROUGH UNDERCUTS THE RIDGE. OVER THE CONUS, 500-HPA HEIGHTS ARE  
FORECAST TO BUILD OVER APPROXIMATELY THE NORTHWESTERN QUARTER OF THE COUNTRY.  
ABOVE NORMAL TEMPERATURES ARE FAVORED ACROSS ALL OF ALASKA, AND ALL AREAS WEST  
OF THE CONTINENTAL DIVIDE. THE TROUGH ANTICIPATED OVER THE EAST-CENTRAL CONUS  
IS PREDICTED TO EXTEND FROM ABOUT THE GREAT LAKES REGION TO THE SOUTHERN  
PLAINS. THIS FEATURE LEADS TO INCREASED ODDS OF BELOW NORMAL TEMPERATURES IN  
THIS REGION. OUT AHEAD OF THIS TROUGH, RESIDUAL WARMTH IS POSSIBLE ACROSS THE  
SOUTHERN ATLANTIC COAST STATES. AS WITH THE 6-10 DAY FORECAST PERIOD, A  
PREDOMINANTLY WET PATTERN IS INDICATED FOR MOST OF THE CONUS. ABOVE NORMAL  
PRECIPITATION IS ALSO FAVORED IN THE SOUTHWEST CONUS, INCLUDING CALIFORNIA,  
EARLY IN THE PERIOD, WHICH APPEARS COUNTER-INTUITIVE TO THE PREDICTED 500-HPA  
RIDGE BUILDING ACROSS THIS REGION. HOWEVER, THIS PRECIPITATION IS ANTICIPATED  
TO MOVE QUICKLY ACROSS AND OUT OF THE SOUTHWEST CONUS DURING THE EARLY STAGES  
OF THE WEEK-2 PERIOD. PRONOUNCED ONSHORE FLOW ACROSS SOUTHERN ALASKA LEADS TO  
ELEVATED ODDS OF ABOVE NORMAL PRECIPITATION, WHILE RIDGING AND ASSOCIATED  
POSITIVE HEIGHT ANOMALIES LEAD TO INCREASED ODDS OF DRIER THAN NORMAL  
CONDITIONS IN NORTHERN ALASKA. THE POTENTIAL FOR UPSLOPE PRECIPITATION, AND A  
DEVELOPING BAROCLINIC ZONE WITH MIXED PRECIPITATION TYPES, WARRANTS A 50  
PERCENT PROBABILITY AREA FOR ABOVE NORMAL PRECIPITATION ACROSS CENTRAL AND  
EASTERN PORTIONS OF THE CONUS.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 25% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 11, 25% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 11, 25% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 25%  
OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
GOOD MODEL AGREEMENT AND AGREEMENT AMONG THE TOOLS, OFFSET BY SOME UNCERTAINTY  
IN THE STRENGTH OF THE EASTERN TROUGH.  
 
FORECASTER: ANTHONY A  
 
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:  
19561230 - 19851220 - 19881213 - 19851228 - 19931224  
 
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:  
19561230 - 19851219 - 19881213 - 19851224 - 19931226  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 08 - 12 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON N N OREGON A A NRN CALIF A A  
SRN CALIF A A IDAHO A A NEVADA A A  
W MONTANA N A E MONTANA B A WYOMING N A  
UTAH A A ARIZONA A A COLORADO A A  
NEW MEXICO A A N DAKOTA B A S DAKOTA B A  
NEBRASKA N A KANSAS N A OKLAHOMA A A  
N TEXAS A A S TEXAS A N W TEXAS A A  
MINNESOTA B A IOWA B A MISSOURI N A  
ARKANSAS N A LOUISIANA A A WISCONSIN B A  
ILLINOIS B A MISSISSIPPI N A MICHIGAN B A  
INDIANA B A OHIO B A KENTUCKY N A  
TENNESSEE N A ALABAMA N A NEW YORK B A  
VERMONT B A NEW HAMP B A MAINE B A  
MASS B A CONN B A RHODE IS B A  
PENN B A NEW JERSEY B A W VIRGINIA B A  
MARYLAND B A DELAWARE B A VIRGINIA N A  
N CAROLINA N A S CAROLINA N A GEORGIA N A  
FL PNHDL N N FL PENIN N N AK N SLOPE A N  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A N  
AK S INT A N AK SO COAST N A AK PNHDL B B  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 10 - 16 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A N OREGON A A NRN CALIF A A  
SRN CALIF A A IDAHO A A NEVADA A A  
W MONTANA A A E MONTANA A A WYOMING A A  
UTAH A A ARIZONA A A COLORADO A A  
NEW MEXICO A A N DAKOTA N A S DAKOTA N A  
NEBRASKA N A KANSAS N A OKLAHOMA B A  
N TEXAS B A S TEXAS B A W TEXAS N A  
MINNESOTA N A IOWA B A MISSOURI B A  
ARKANSAS B A LOUISIANA B A WISCONSIN B A  
ILLINOIS B A MISSISSIPPI B A MICHIGAN B A  
INDIANA B A OHIO B A KENTUCKY B A  
TENNESSEE B A ALABAMA N A NEW YORK N A  
VERMONT N A NEW HAMP N A MAINE N A  
MASS N A CONN N A RHODE IS N A  
PENN N A NEW JERSEY N A W VIRGINIA N A  
MARYLAND N A DELAWARE N A VIRGINIA N A  
N CAROLINA N A S CAROLINA N A GEORGIA N A  
FL PNHDL A A FL PENIN A A AK N SLOPE A B  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A N  
AK S INT A A AK SO COAST A A AK PNHDL A 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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