489  
FXUS06 KWBC 162002  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EST FRI FEBRUARY 16 2018  
 
6-10 DAY OUTLOOK FOR FEB 22 - 26 2018  
 
TODAY'S ENSEMBLE MEAN SOLUTIONS ARE IN VERY GOOD AGREEMENT ON THE EXPECTED  
500-HPA FLOW PATTERN OVER THE FORECAST DOMAIN. A DEEP TROUGH IS FORECAST NORTH  
OF HUDSON BAY EXTENDING EAST/SOUTHEAST OVER THE NORTH ATLANTIC, AND  
SOUTHWESTWARD OVER THE WESTERN CONUS. RIDGES ARE ANTICIPATED OVER FLORIDA AND  
WESTERN MAINLAND ALASKA. THE FLOW PATTERN IS PREDICTED TO BE RELATIVELY  
AMPLIFIED. THE ENSEMBLE SPAGHETTI CHARTS GENERALLY INDICATE LOW TO MODERATE  
SPREAD OVER THE CONUS, AND MODERATE TO LARGE SPREAD OVER THE PACIFIC. THE AO  
INDEX WHICH RECENTLY HAS BEEN STRONGLY POSITIVE IS FORECAST TO BE CLOSE TO ZERO  
BY DAY 7, BE STRONGLY NEGATIVE AT DAY 10, AND REMAIN STRONGLY NEGATIVE AT DAY  
14. THERE IS LARGE SPREAD AMONG THE GFS ENSEMBLE MEMBERS REGARDING THE FORECAST  
STRENGTH OF THE AO INDEX ESPECIALLY BEYOND DAY 7. THE PNA INDEX WHICH RECENTLY  
HAS BEEN WEAKLY NEGATIVE IS FORECAST TO REMAIN WEAKLY NEGATIVE THROUGH DAY 14.  
TODAY'S 500-HPA BLEND CHART INDICATES NEAR TO ABOVE NORMAL HEIGHTS OVER MOST OF  
THE EASTERN TWO-THIRDS OF THE CONUS, THE ALEUTIANS, AND CENTRAL AND WESTERN  
MAINLAND ALASKA, AND NEAR TO BELOW NORMAL HEIGHTS OVER MUCH OF THE WESTERN  
THIRD OF THE CONUS, EXTREME EASTERN MAINLAND ALASKA, AND THE ALASKA PANHANDLE.  
 
ANOMALOUS RIDGING OVER ALASKA FAVORS ABOVE NORMAL TEMPERATURES FOR MUCH OF  
CENTRAL AND NORTHERN MAINLAND ALASKA AS WELL AS THE ALEUTIANS. ANOMALOUS  
NORTHERLY FLOW TILTS THE ODDS TO BELOW NORMAL TEMPERATURES FOR PARTS OF THE  
ALASKA PANHANDLE. PERSISTENT TROUGHING IN THE WESTERN CONUS LEADS TO INCREASED  
CHANCES FOR BELOW NORMAL TEMPERATURES FOR MUCH OF THE WESTERN AND NORTH-CENTRAL  
CONUS, ESPECIALLY FOR THE NORTHWESTERN CONUS WHERE NEGATIVE HEIGHT ANOMALIES  
ARE THE LARGEST. A STRONG RIDGE FORECAST OVER THE SOUTHEASTERN U.S. LEADS TO  
ENHANCED CHANCES OF ABOVE NORMAL TEMPERATURES FOR THE EASTERN CONUS AND THE  
SOUTHERN PLAINS.  
 
SURFACE LOW PRESSURE OVER THE GULF OF ALASKA/ALASKA PANHANDLE FAVORS ABOVE  
NORMAL PRECIPITATION FOR MUCH OF ALASKA AND THE NORTHWEST CONUS. NEAR TO BELOW  
NORMAL PRECIPITATION IS FAVORED FOR THE WEST COAST (WITH THE EXCEPTION OF THE  
PACIFIC NORTHWEST), WEST OF THE TROUGH AXIS. A STATIONARY FRONT IS EXPECTED TO  
SETUP ACROSS TEXAS, THE MIDDLE MISSISSIPPI VALLEY, OHIO VALLEY, AND NORTHEAST,  
FAVORING INCREASED STORM SYSTEM ACTIVITY AND ABOVE NORMAL PRECIPITATION.  
SUBSIDENCE BEHIND THE FRONTAL SYSTEM ENHANCES PROBABILITIES FOR BELOW NORMAL  
PRECIPITATION FOR PARTS OF THE NORTHERN PLAINS, SOUTHERN AND CENTRAL ROCKIES  
AND SOUTHWEST. BENEATH THE HIGHLY ANOMALOUS SOUTHEAST RIDGE, BELOW NORMAL  
PRECIPITATION IS FAVORED FOR PARTS OF GEORGIA, SOUTH CAROLINA, AND FLORIDA.  
 
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, 20% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 20% OF  
YESTERDAY'S 12Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 7, 10% OF TODAY'S 0Z  
CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8, AND 10% OF YESTERDAY'S 12Z CANADIAN  
ENSEMBLE MEAN CENTERED ON DAY 7  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 5 OUT OF 5, DUE TO  
VERY GOOD AGREEMENT AMONG THE MODELS AND FORECAST TOOLS.  
 
8-14 DAY OUTLOOK FOR FEB 24 - MAR 02, 2018  
 
BY THE WEEK-2 PERIOD, THE LARGE-SCALE PATTERN OVER THE FORECAST DOMAIN IS  
EXPECTED TO BE SHIFTED SLIGHTLY WEST, AND BE SLIGHTLY LESS AMPLIFIED, BUT  
OTHERWISE REMAIN LARGELY UNCHANGED. THE HEIGHT ANOMALIES DEPICTED IN THE MANUAL  
500-HPA BLEND ARE RELATIVELY LARGE FOR THE WEEK-2 PERIOD, SUGGESTING VERY GOOD  
MODEL AGREEMENT AND CERTAINTY. ABOVE NORMAL HEIGHTS ARE EXPECTED OVER THE  
EASTERN TWO-THIRDS OF THE CONUS, SOUTHWESTERN MAINLAND ALASKA, AND THE  
ALEUTIANS, WHILE BELOW NORMAL HEIGHTS ARE ANTICIPATED OVER THE WESTERN THIRD OF  
THE CONUS, THE REMAINDER OF MAINLAND ALASKA, AND THE ALASKA PANHANDLE.  
 
THE WEEK-2 TEMPERATURE PROBABILITY FORECAST IS VERY SIMILAR TO THE 6-10 DAY  
FORECAST, EXCEPT SLIGHTLY LOWER PROBABILITIES DUE TO THE TYPICALLY INCREASED  
UNCERTAINTY IN THE WEEK-2 PERIOD, AND A GENERAL WESTWARD DISPLACEMENT OF THE  
TEMPERATURE ANOMALY PATTERN DUE TO AN EXPECTED RETROGRESSION OF THE OVERALL  
LONG WAVE HEIGHT PATTERN. THE WEEK-2 PRECIPITATION PROBABILITY FORECAST IS ALSO  
VERY SIMILAR TO THE 6-10 DAY FORECAST, EXCEPT MOST OF THE AREAS OF ANOMALOUS  
PRECIPITATION ARE SHIFTED A BIT WESTWARD. A WETTER PATTERN IS FAVORED OVER THE  
SOUTHWESTERN CONUS AS THE TROUGH AXIS SHIFTS SLIGHTLY WESTWARD, WHILE PARTS OF  
THE NORTHEAST ARE FAVORED TO BE DRIER AS THE AREA OF ABOVE NORMAL HEIGHTS ALSO  
SHIFTS SLIGHTLY WESTWARD.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 10% OF TODAY'S 0Z GFS  
ENSEMBLE MEAN CENTERED ON DAY 11, 20% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED  
ON DAY 11, 10% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 11, 30% OF  
TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 20% OF YESTERDAY'S 12Z  
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 10, AND 10% 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  
VERY GOOD AGREEMENT AMONG THE MODELS AND TEMPERATURE TOOLS OFFSET BY POOR  
AGREEMENT AMONG THE PRECIPITATION TOOLS OVER PARTS OF THE CONUS.  
 
FORECASTER: RANDY S  
 
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  
MARCH 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:  
19850301 - 19970227 - 19850224 - 19890213 - 20040302  
 
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:  
19850301 - 19970228 - 19750126 - 19850224 - 19740126  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR FEB 22 - 26 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B B  
SRN CALIF B B IDAHO B N NEVADA B B  
W MONTANA B N E MONTANA B B WYOMING B B  
UTAH B B ARIZONA B B COLORADO B B  
NEW MEXICO B B N DAKOTA B B S DAKOTA B B  
NEBRASKA B B KANSAS B N OKLAHOMA A A  
N TEXAS A A S TEXAS A A W TEXAS N N  
MINNESOTA B B IOWA N N MISSOURI A A  
ARKANSAS A A LOUISIANA A A WISCONSIN A N  
ILLINOIS A A MISSISSIPPI A A MICHIGAN A N  
INDIANA A A OHIO A A KENTUCKY A A  
TENNESSEE A A ALABAMA A N 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 N GEORGIA A N  
FL PNHDL A B FL PENIN A B AK N SLOPE A A  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A  
AK S INT N A AK SO COAST N A AK PNHDL N A  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR FEB 24 - MAR 02, 2018  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON B A OREGON B A NRN CALIF B N  
SRN CALIF B A IDAHO B A NEVADA B A  
W MONTANA B A E MONTANA B N WYOMING B B  
UTAH B A ARIZONA B A COLORADO B B  
NEW MEXICO N B N DAKOTA B B S DAKOTA B B  
NEBRASKA N B KANSAS A N OKLAHOMA A A  
N TEXAS A A S TEXAS A A W TEXAS A A  
MINNESOTA A N IOWA A A MISSOURI A A  
ARKANSAS A A LOUISIANA A N 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 N NEW YORK A A  
VERMONT A A NEW HAMP A N MAINE A B  
MASS A N CONN A N RHODE IS A N  
PENN A A NEW JERSEY A N W VIRGINIA A A  
MARYLAND A N DELAWARE A N VIRGINIA A N  
N CAROLINA A N S CAROLINA A N GEORGIA A B  
FL PNHDL A B FL PENIN A B AK N SLOPE A A  
AK ALEUTIAN A A AK WESTERN A A AK INT BSN N A  
AK S INT B A 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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