237  
FXUS06 KWBC 032004  
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 03 2018  
 
6-10 DAY OUTLOOK FOR JAN 09 - 13 2018  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN GOOD AGREEMENT (ESPECIALLY IN REGARD TO  
PHASE) 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 NEAR THE CALIFORNIA COAST, THOUGH  
THE 0Z CANADIAN ENSEMBLE MEAN DEPICTS THIS FEATURE WELL INLAND ACROSS THE FOUR  
CORNERS REGION. 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. THE DETERMINISTIC 6Z, AND ESPECIALLY  
THE 0Z, GFS RUNS PREDICT THE DEEPEST ANOMALOUS TROUGH OF ALL THE SOLUTIONS, BUT  
THESE ARE NOT AMONG THE BETTER PERFORMERS ACCORDING TO ANOMALY CORRELATION  
SCORES DURING THE PAST 60 DAYS. ACCORDINGLY, THEY WERE GIVEN LITTLE WEIGHT IN  
THE OFFICIAL BLENDED HEIGHT FORECAST. ENSEMBLE SPREAD (AT 5760 M) IS LOW TO  
MODERATE OVER THE CONUS, AND MODERATE TO LARGE 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  
ANOMALOUS 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 PRACTICALLY ALL AREAS WEST OF THE CONTINENTAL DIVIDE, AND FROM  
THE SOUTHERN HIGH PLAINS OUT ACROSS SOUTHERN TEXAS. 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 EASTWARD ACROSS THE GREAT LAKES REGION. POSITIVE HEIGHT ANOMALIES AHEAD  
OF THE EASTERN TROUGH FAVOR ABOVE NORMAL TEMPERATURES OVER THE SOUTHERN  
ATLANTIC COAST STATES, AND PARTS OF THE CENTRAL GULF COAST. ELSEWHERE, WHICH  
INCLUDES MUCH OF THE CONUS EAST OF THE ROCKIES, UNCERTAINTY IN THE PREDICTED  
AMPLITUDE OF THE EASTERN TROUGH WARRANTS EXTENSIVE COVERAGE OF NEAR NORMAL  
TEMPERATURES. 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.  
 
PERSISTENT LOW PRESSURE NEAR THE ALEUTIAN ARCHIPELAGO FAVORS ABOVE NORMAL  
PRECIPITATION FOR SOUTHWESTERN ALASKA DURING THE 6-10 DAY PERIOD. 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. FAR SOUTHERN AREAS OF THE CONUS ARE  
EXPECTED TO MISS OUT ON MOST, IF NOT ALL, OF THE PRECIPITATION DURING THIS  
PERIOD. 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 11 - 17 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 MUCH OF THE WEST. ABOVE NORMAL TEMPERATURES ARE FAVORED  
ACROSS ALL OF ALASKA, AND ALL AREAS WEST OF THE CONTINENTAL DIVIDE. EAST OF THE  
DIVIDE, THE CHANCES FOR ABOVE NORMAL TEMPERATURES EXTEND ACROSS THE HIGH PLAINS  
REGION, AND ALSO OVER THE SOUTHERN ATLANTIC REGION. THE LATTER OF THE TWO  
REGIONS IS EXPECTED TO BE EAST OF A TROUGH, WITH ACCOMPANYING SOUTHWESTERLY  
SURFACE FLOW AND POSITIVE MID-TROPOSPHERIC HEIGHT ANOMALIES. A TROUGH IS  
FORECAST FROM THE GREAT LAKES SOUTHWESTWARD TO THE SOUTHERN PLAINS, WHICH  
FAVORS MODEST TILTS TOWARD BELOW NORMAL TEMPERATURES IN THIS BROAD ZONE.  
 
FOR THE WEEK-2 PRECIPITATION OUTLOOK, 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 THE CENTRAL INTERIOR OF ALASKA. CLIMATOLOGICALLY DRY  
CONDITIONS ARE EXPECTED ACROSS THE NORTH SLOPE. MOISTURE ASSOCIATED WITH THE  
LEADING PORTION OF THE DEEPENING TROUGH PREDICTED OVER THE GULF OF ALASKA IS  
FORECAST TO MOVE INTO THE PACIFIC NORTHWEST DURING WEEK-2. THE ODDS OF ABOVE  
NORMAL PRECIPITATION ARE ENHANCED FROM CENTRAL PORTIONS OF THE GREAT PLAINS AND  
THE UPPER AND MIDDLE MISSISSIPPI VALLEY EASTWARD TO THE ATLANTIC COAST, FROM  
MAINE TO NORTH CAROLINA. THIS IS GENERALLY ATTRIBUTED TO STORM ACTIVITY EAST OF  
THE TROUGH THAT IS ANTICIPATED OVER THE CENTRAL CONUS. SLIGHT TILTS TOWARD  
BELOW NORMAL PRECIPITATION ARE FAVORED ACROSS A LARGE PART OF THE WEST AND  
SOUTHERN PLAINS, WITH THE RAPID TRANSITION THAT IS PREDICTED FROM ANOMALOUSLY  
WET TO DRY CONDITIONS BETWEEN THE 6-10 DAY AND 8-14 DAY PERIODS.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 20% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 11, 25% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 11, 30% 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 POSITION AND AMPLITUDE OF THE CENTRAL CONUS 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 - 19881214 - 19931224 - 19851228  
 
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:  
19881214 - 19561230 - 19851219 - 19851224 - 19891224  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 09 - 13 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 N A E MONTANA N A WYOMING A A  
UTAH A A ARIZONA A A COLORADO A A  
NEW MEXICO A A N DAKOTA B A S DAKOTA N A  
NEBRASKA N A KANSAS N A OKLAHOMA N A  
N TEXAS N A S TEXAS A B W TEXAS A N  
MINNESOTA B A IOWA N A MISSOURI N A  
ARKANSAS N A LOUISIANA N N WISCONSIN B A  
ILLINOIS N A MISSISSIPPI N A MICHIGAN B A  
INDIANA N A OHIO N A KENTUCKY N A  
TENNESSEE N 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 A A GEORGIA A N  
FL PNHDL A N FL PENIN A B AK N SLOPE A B  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A B  
AK S INT A N AK SO COAST N N AK PNHDL B B  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 11 - 17 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A A OREGON A N NRN CALIF A B  
SRN CALIF A B IDAHO A B NEVADA A B  
W MONTANA A B E MONTANA A B WYOMING A N  
UTAH A B ARIZONA A B COLORADO A N  
NEW MEXICO A B N DAKOTA A N S DAKOTA N N  
NEBRASKA N A KANSAS N A OKLAHOMA B A  
N TEXAS B N S TEXAS B B W TEXAS A B  
MINNESOTA N A IOWA N A MISSOURI B A  
ARKANSAS B A LOUISIANA B N WISCONSIN B A  
ILLINOIS B A MISSISSIPPI N N MICHIGAN B A  
INDIANA B A OHIO B A KENTUCKY N A  
TENNESSEE N A ALABAMA N N 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 A N GEORGIA A N  
FL PNHDL A N FL PENIN A N AK N SLOPE A N  
AK ALEUTIAN A A AK WESTERN A B AK INT BSN A B  
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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