195  
FXUS06 KWBC 042022  
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 04 2018  
 
6-10 DAY OUTLOOK FOR JAN 10 - 14 2018  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN GOOD AGREEMENT ON THE PREDICTED 500-HPA  
FLOW PATTERN OVER THE FORECAST DOMAIN. A HIGHLY AMPLIFIED RIDGE IS EXPECTED  
NEAR THE WEST COAST OF NORTH AMERICA, AND A ZONALLY-ORIENTED TROUGH IS  
PREDICTED FROM THE BERING SEA ACROSS THE ALEUTIANS TO THE GULF OF ALASKA. THE  
POLAR VORTEX IS ANTICIPATED ACROSS NORTHEASTERN NORTH AMERICA. DURING THE PAST  
60 DAYS, ALL ENSEMBLE MEANS CONTINUE TO OUTPERFORM THE DETERMINISTIC RUNS, AS  
INDICATED BY ANOMALY CORRELATION SCORES. ACCORDINGLY, 80 PERCENT OF THE  
OFFICIAL HEIGHT BLEND WAS COMPOSED OF ENSEMBLE MEAN SOLUTIONS, WITH THE  
REMAINING 20 PERCENT COMPOSED OF DETERMINISTIC RUNS. ENSEMBLE SPREAD (AT 5760  
M) IS LOW TO MODERATE OVER THE CONUS AND EASTERN PACIFIC.  
 
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. THE RIDGE PREDICTED OVER WESTERN  
NORTH AMERICA AND ASSOCIATED POSITIVE HEIGHT ANOMALIES FAVOR ABOVE NORMAL  
TEMPERATURES FOR MOST OF THIS AREA (INCLUDING ALL AREAS WEST OF THE CONTINENTAL  
DIVIDE IN THE LOWER 48 STATES). THE EXCEPTION IS OVER PARTS OF SOUTHEAST  
MAINLAND ALASKA AND THE PANHANDLE, IN ASSOCIATION WITH A DEPARTING TROUGH. ODDS  
OF BELOW NORMAL TEMPERATURES ARE ELEVATED FROM THE NORTHERN AND CENTRAL PLAINS  
TO MICHIGAN AND MAINE. THIS IS DUE TO THE EXPECTATION OF SHORTWAVE ENERGY  
DIGGING SOUTHWARD ALONG THE WESTERN SIDE OF THE LONGWAVE TROUGH ANTICIPATED  
OVER EASTERN NORTH AMERICA; RESULTING IN A WESTWARD SHIFT OF THE COLDER AIR  
FROM THE EASTERN CONUS INTO THE CENTRAL CONUS. THIS, IN TURN, ALLOWS FOR HIGHER  
HEIGHTS TO BUILD BACK INTO THE EAST, ENHANCING THE CHANCES OF ABOVE NORMAL  
TEMPERATURES, SIGNIFYING A BREAK IN THE VERY COLD PATTERN THAT HAS BEEN IN  
PLACE OVER THE EASTERN CONUS FOR THE PAST FEW WEEKS.  
 
PERSISTENT LOW PRESSURE NEAR THE ALEUTIAN ARCHIPELAGO FAVORS ABOVE NORMAL  
PRECIPITATION FOR THE SOUTHERN COAST OF ALASKA DURING THE 6-10 DAY PERIOD.  
DRIER THAN NORMAL CONDITIONS ARE FAVORED OVER THE CENTRAL INTERIOR OF ALASKA  
WITH ENHANCED DOWNSLOPE WINDS EXPECTED OFF THE ALASKA RANGE. THE PREDOMINANTLY  
WET PATTERN PREDICTED OVER THE CONUS DURING THE PAST SEVERAL DAYS IS AGAIN  
PREDICTED TODAY, THOUGH A RAPID TRANSITION TO BELOW NORMAL PRECIPITATION IS  
ANTICIPATED DURING WEEK-2. 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 AGREEMENT AMONG MOST MODELS AND TOOLS.  
 
8-14 DAY OUTLOOK FOR JAN 12 - 18 2018  
 
DURING WEEK-2, MODELS ARE IN FAIRLY GOOD AGREEMENT THAT RIDGING WILL CONTINUE  
ACROSS MUCH OF ALASKA, BUT GIVE WAY ACROSS THE SOUTHERN PORTION OF THE STATE TO  
AN UNDERCUTTING TROUGH. ABOVE NORMAL TEMPERATURES ARE STILL FAVORED IN ALASKA,  
BUT WITH DIMINISHING PROBABILITIES (COMPARED TO THE 6-10 DAY PERIOD) AS THE  
LARGEST POSITIVE HEIGHT DEPARTURES SHIFT NORTHWARD OVER THE NORTH SLOPE REGION  
AND ARCTIC OCEAN. OVER THE WESTERN CONUS, RIDGING AND HIGHER 500-HPA HEIGHTS  
ARE FORECAST TO BUILD FARTHER EAST INTO THE CENTRAL STATES. RELATIVE WARMTH IS  
EXPECTED TO SPREAD EASTWARD ACROSS MOST OF THE GREAT PLAINS AND THE UPPER  
MISSISSIPPI VALLEY. THE TROUGH PREDICTED OVER THE EAST-CENTRAL CONUS IS LIKELY  
TO WEAKEN, WITH MOST OF THIS REGION EXPECTED TO HAVE NEAR NORMAL TEMPERATURES,  
WITH THE POSSIBLE EXCEPTION OF EASTERN TEXAS AND THE LOWER MISSISSIPPI VALLEY,  
WHERE ODDS FAVOR BELOW NORMAL TEMPERATURES. AFTER SEVERAL WEEKS OF VERY COLD  
WEATHER, THE EAST IS EXPECTED TO UNDERGO A TRANSITION TO A SIGNIFICANTLY MILDER  
PATTERN. ABOVE NORMAL TEMPERATURES ARE THEREFORE ANTICIPATED ACROSS THE  
ATLANTIC COAST STATES, IN ADVANCE OF AN APPROACHING TROUGH, AND IN ASSOCIATION  
WITH MODERATELY LARGE POSITIVE HEIGHT ANOMALIES. THE ECMWF SOLUTION IS FASTER  
WITH THE PROJECTED MODERATION IN SURFACE TEMPERATURES, COMPARED TO THE SLOWER  
GEFS SOLUTION.  
 
FOR THE WEEK-2 PRECIPITATION OUTLOOK, THE ONLY NOTABLE CHANGE MADE IN THE  
ALASKA SECTOR WAS TO TRANSITION THE ALEUTIANS FROM ABOVE NORMAL PRECIPITATION  
(IN THE 6-10 DAY PERIOD) TO NEAR NORMAL, AS THE ANTICIPATED TROUGH IN THIS  
VICINITY IS EXPECTED TO BE EAST OF THIS REGION. MOISTURE ASSOCIATED WITH THE  
LEADING PORTION OF THIS TROUGH PREDICTED OVER THE GULF OF ALASKA IS FORECAST TO  
MOVE INTO THE PACIFIC NORTHWEST DURING WEEK-2, FAVORING ABOVE NORMAL  
PRECIPITATION THERE. THE MOST SIGNIFICANT ADJUSTMENT RENDERED TO THE  
PRECIPITATION OUTLOOK FROM THE 6-10 DAY PERIOD IS THE RAPID EASTWARD SHIFT OF  
REMAINING ABOVE NORMAL PRECIPITATION TO OVER THE EASTERN CONUS, WITH DRIER THAN  
NORMAL CONDITIONS NOW EXPECTED TO SPREAD RAPIDLY ACROSS THE WESTERN AND CENTRAL  
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, 30% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 20%  
OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: NEAR AVERAGE, 3 OUT OF 5, DUE TO  
REASONABLE OVERALL MODEL AND TOOL AGREEMENT, BUT OFFSET BY THE UNCERTAINTY  
INHERENT IN A (PREDICTED) RAPIDLY TRANSITIONING CIRCULATION PATTERN.  
 
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 - 19881216 - 19851227 - 19851220 - 20090116  
 
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 - 19881214 - 19851226 - 19851219 - 20090117  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 10 - 14 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A N OREGON A N NRN CALIF A N  
SRN CALIF A N IDAHO A A NEVADA A A  
W MONTANA A A E MONTANA B A WYOMING A A  
UTAH A A ARIZONA A A COLORADO A A  
NEW MEXICO A A N DAKOTA B A S DAKOTA B A  
NEBRASKA B A KANSAS N A OKLAHOMA N A  
N TEXAS N N S TEXAS N N W TEXAS A B  
MINNESOTA B A IOWA B A MISSOURI N A  
ARKANSAS N A LOUISIANA N N WISCONSIN B A  
ILLINOIS B A MISSISSIPPI A A MICHIGAN B A  
INDIANA N A OHIO N A KENTUCKY N A  
TENNESSEE A A ALABAMA A N NEW YORK N A  
VERMONT N A NEW HAMP N A MAINE N A  
MASS N A CONN A A RHODE IS A A  
PENN N A NEW JERSEY A A W VIRGINIA A A  
MARYLAND A A DELAWARE A A VIRGINIA A A  
N CAROLINA A N S CAROLINA A N GEORGIA A N  
FL PNHDL A B FL PENIN A B AK N SLOPE A N  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A B  
AK S INT A A AK SO COAST N A AK PNHDL B A  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR JAN 12 - 18 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A A OREGON A A NRN CALIF A B  
SRN CALIF A B IDAHO A N NEVADA A B  
W MONTANA A N E MONTANA A B WYOMING A B  
UTAH A B ARIZONA A B COLORADO A B  
NEW MEXICO A B N DAKOTA A B S DAKOTA A B  
NEBRASKA A B KANSAS A B OKLAHOMA A B  
N TEXAS N B S TEXAS B B W TEXAS A B  
MINNESOTA A N IOWA A B MISSOURI N B  
ARKANSAS N B LOUISIANA B B WISCONSIN N N  
ILLINOIS N N MISSISSIPPI B B MICHIGAN N N  
INDIANA N N OHIO N N KENTUCKY N N  
TENNESSEE N N ALABAMA N N NEW YORK N A  
VERMONT N A NEW HAMP A A MAINE N A  
MASS A A CONN A A RHODE IS A A  
PENN N N NEW JERSEY A A W VIRGINIA N N  
MARYLAND A N DELAWARE A A VIRGINIA A N  
N CAROLINA A A S CAROLINA A A GEORGIA N N  
FL PNHDL A N FL PENIN A A AK N SLOPE A N  
AK ALEUTIAN A N 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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