897
FXUS06 KWBC 201901
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT SAT SEPTEMBER 20 2025
6-10 DAY OUTLOOK FOR SEP 26 - 30 2025
WHILE THE 0Z ECMWF, GEFS, AND CANADIAN ENSEMBLE MEANS AGREE ON THE FORECAST OF
AN AMPLIFIED LARGE-SCALE 500-HPA HEIGHT PATTERN OVER NORTH AMERICA AND
SURROUNDING REGIONS DURING THE 6-10 DAY PERIOD, SOME DIFFERENCES ARE SEEN IN
ANOMALY AMPLITUDES AND LOCATION, AS WELL AS THE DAILY EVOLUTION OF THE PATTERN.
MODELS PREDICT A RIDGE AND ASSOCIATED POSITIVE 500-HPA HEIGHT ANOMALIES OVER
THE ALEUTIAN ISLANDS. AN AMPLIFIED TROUGH IS PREDICTED DOWNSTREAM FROM MAINLAND
ALASKA SOUTHWARD INTO THE NORTHEAST PACIFIC NEAR THE PACIFIC COAST OF NORTH
AMERICA. THIS PREDICTED TROUGH DEAMPLIFIES AROUND DAYS 9 AND 10 IN THE ECMWF
ENSEMBLE MEAN, WHILE REMAINING MORE AMPLIFIED IN THE GEFS AND CANADIAN ENSEMBLE
MEANS. OVER THE CONTIGUOUS UNITED STATES (CONUS), MODEL ENSEMBLE MEANS PREDICT
A RIDGE AND ASSOCIATED POSITIVE 500-HPA HEIGHT ANOMALIES OVER MOST OF CANADA
AND THE NORTHERN CENTRAL AND NORTHEASTERN CONUS. NEGATIVE 500-HPA HEIGHT
ANOMALIES ARE PREDICTED OVER THE PACIFIC NORTHWEST IN THE GEFS AND CANADIAN
ENSEMBLE MEANS, WHILE THE ECMWF PREDICTS NEAR ZERO 500-HPA HEIGHT ANOMALIES
OVER THIS REGION. A SHORTWAVE TROUGH AND NEGATIVE 500-HPA HEIGHT ANOMALIES ARE
PREDICTED CENTERED OVER THE TENNESSEE VALLEY AT THE START OF THE 6-10 DAY
PERIOD, WHICH DEAMPLIFY IN EACH OF THE ENSEMBLE MEANS BY AROUND THE MIDDLE OF
THE PERIOD.
IN THE 6-10 DAY PERIOD, ABOVE NORMAL TEMPERATURES ARE FAVORED ACROSS THE
ALEUTIAN ISLANDS, UNDER POSITIVE 500-HPA HEIGHT ANOMALIES. BELOW NORMAL
TEMPERATURES ARE FAVORED FOR PARTS OF INTERIOR MAINLAND ALASKA AND FOR
SOUTHEAST ALASKA, UNDER THE PREDICTED TROUGH. ABOVE NORMAL TEMPERATURES ARE
LIKELY OVER MOST OF THE CONUS, UNDER THE PREDICTED RIDGE AND POSITIVE 500-HPA
HEIGHT ANOMALIES. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE PACIFIC
NORTHWEST DESPITE WEAK NEGATIVE 500-HPA HEIGHT ANOMALIES, DUE TO STRONG PACIFIC
FLOW AND POSITIVE SEA SURFACE TEMPERATURE ANOMALIES OVER THE NORTH PACIFIC.
NEAR NORMAL TEMPERATURES ARE SLIGHTLY MORE LIKELY THAN ABOVE NORMAL
TEMPERATURES OVER PARTS OF THE SOUTHWEST, WHERE MODEL TOOLS INDICATE THE
POSSIBILITY OF COOLER TEMPERATURES, RELATED TO PRECIPITATION AND CLOUDINESS.
THE LIKELIHOOD OF ABOVE NORMAL TEMPERATURES IS ALSO DECREASED FOR PARTS OF THE
SOUTHERN PLAINS AND CENTRAL MISSISSIPPI VALLEY, WHERE A SHORTWAVE TROUGH EARLY
IN THE PERIOD MODERATES TEMPERATURES. ABOVE NORMAL TEMPERATURES ARE LIKELY
ACROSS THE HAWAIIAN ISLANDS, CONSISTENT WITH THE TEMPERATURE CONSOLIDATION.
ABOVE NORMAL PRECIPITATION IS FAVORED FOR MOST OF THE ALEUTIANS DURING THE 6-10
DAY PERIOD, CONSISTENT WITH MOST MODEL PRECIPITATION FORECASTS. ABOVE NORMAL
PRECIPITATION IS FAVORED FOR MOST OF MAINLAND ALASKA, EXCLUDING THE SOUTH
COAST, AND FOR SOUTHEAST ALASKA, RELATED TO THE PREDICTED TROUGH OVER THE STATE
AND NORTHEAST PACIFIC. ABOVE NORMAL PRECIPITATION IS FAVORED FOR THE WEST
COAST, AHEAD OF THE PREDICTED TROUGH. ENHANCED PROBABILITIES FOR ABOVE NORMAL
PRECIPITATION IS INDICATED OVER THE SOUTHWEST CONSISTENT WITH MODEL
PRECIPITATION TOOLS AND THE CONSOLIDATION OF CALIBRATED ECMWF AND GEFS
PRECIPITATION FORECASTS. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FROM THE
LOWER MISSISSIPPI VALLEY ACROSS THE SOUTHEAST, OHIO VALLEY, THE MID-ATLANTIC,
AND SOUTHERN NEW ENGLAND, RELATED TO A PREDICTED SHORTWAVE TROUGH DURING THE
FIRST HALF OF THE 6-10 DAY PERIOD. ABOVE NORMAL PRECIPITATION IS FAVORED FOR
MOST OF THE HAWAIIAN ISLANDS EXCLUDING THE BIG ISLAND, CONSISTENT WITH THE
PRECIPITATION CONSOLIDATION.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 30% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY
8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO
GOOD AGREEMENT BETWEEN ENSEMBLE MODEL FORECASTS OF AN AMPLIFIED MID-LEVEL
HEIGHT PATTERN, OFFSET BY DIFFERENCES AMONG TEMPERATURE AND PRECIPITATION
FORECAST TOOLS FOR SOME AREAS AND AN EVOLVING MID-LEVEL CIRCULATION PATTERN.
8-14 DAY OUTLOOK FOR SEP 28 - OCT 04, 2025
SOME DIFFERENCES APPEAR IN THE CANADIAN, ECMWF, AND GEFS ENSEMBLE MEAN
FORECASTS FOR THE 500-HPA HEIGHT PATTERN OVER NORTH AMERICA DURING THE 8-14 DAY
PERIOD, AS THE PATTERN EVOLVES AND PARTLY DEAMPLIFIES. POSITIVE 500-HPA HEIGHT
ANOMALIES CONTINUE OVER THE ALEUTIAN ISLANDS IN THE RECENT GEFS ENSEMBLE MEAN
FORECAST, WHILE THE ECMWF ENSEMBLE MEAN PREDICTS NEAR ZERO 500-HPA HEIGHT
ANOMALIES ACROSS THE ALEUTIANS IN WEEK 2. THE ECMWF ENSEMBLE MEAN PREDICTS
DEAMPLIFICATION OF THE TROUGH AND ASSOCIATED NEGATIVE 500-HPA HEIGHT ANOMALIES
OVER THE NORTHEAST PACIFIC LATER IN THE 8-14 DAY PERIOD, WHILE A SECOND TROUGH
AMPLIFIES OVER THE BERING SEA. THE GEFS PREDICTS PERSISTENCE OF THE TROUGH AND
NEGATIVE 500-HPA HEIGHT ANOMALIES OVER THE NORTHEAST PACIFIC. OVER THE CONUS,
ALL ENSEMBLE MEANS GENERALLY AGREE ON PERSISTENCE OF POSITIVE 500-HPA HEIGHT
ANOMALIES THROUGH WEEK 2. THE ECMWF PREDICTS POSITIVE 500-HPA HEIGHT ANOMALIES
OVER THE PACIFIC NORTHWEST IN THE 8-14 DAY MEAN, WHILE THE GEFS AND CANADIAN
MODELS PREDICT SLIGHTLY NEGATIVE 500-HPA HEIGHT ANOMALIES OVER THE REGION.
THE TEMPERATURE PATTERN FOR ALASKA SOMEWHAT PERSISTS FROM THE 6-10 DAY PERIOD
TO THE 8-14 DAY PERIOD. ABOVE NORMAL TEMPERATURES ARE FAVORED OVER PARTS OF THE
ALEUTIAN ISLANDS AND THE SOUTHWESTERN COAST OF MAINLAND ALASKA IN THE 8-14 DAY
PERIOD, UNDER A DEAMPLIFYING POSITIVE 500-HPA HEIGHT ANOMALY IN THE MANUAL
BLEND OF MODEL FORECASTS. BELOW NORMAL TEMPERATURES ARE SLIGHTLY FAVORED OVER
PARTS OF NORTHWESTERN MAINLAND ALASKA, CONSISTENT WITH A BLEND OF DYNAMICAL
MODEL FORECASTS. ABOVE NORMAL TEMPERATURES ARE FAVORED OVER PARTS OF
SOUTHEASTERN MAINLAND ALASKA IN WEEK 2, WHILE NEAR NORMAL TEMPERATURES ARE NOW
FAVORED FOR SOUTHEAST ALASKA, CONSISTENT WITH RISING MID-LEVEL HEIGHTS. ABOVE
NORMAL TEMPERATURES ARE LIKELY ACROSS NEARLY THE ENTIRE CONUS IN THE 8-14 DAY
PERIOD, UNDER POSITIVE 500-HPA HEIGHT ANOMALIES. ABOVE NORMAL TEMPERATURES ARE
LIKELY ACROSS HAWAII IN THE 8-14 DAY PERIOD, CONSISTENT WITH THE TEMPERATURE
CONSOLIDATION.
WITH THE VARYING MID-LEVEL HEIGHT FORECAST AND A WEAKENING TROUGH OVER THE
REGION, PROBABILITIES FOR ABOVE NORMAL PRECIPITATION REMAIN SLIGHTLY ENHANCED
FOR SOUTHEAST ALASKA AND FOR MOST OF MAINLAND ALASKA, EXCLUDING THE
SOUTHWESTERN MAINLAND, CONSISTENT WITH MOST MODEL TOOLS. FOR THE CONUS, ABOVE
NORMAL PRECIPITATION CONTINUES TO BE SLIGHTLY FAVORED FOR THE WEST FROM THE
PACIFIC COAST TO THE ROCKY MOUNTAINS, AHEAD OF A WEAKENING TROUGH OVER THE
PACIFIC. PROBABILITIES FOR ABOVE NORMAL PRECIPITATION ARE SLIGHTLY ENHANCED FOR
THE SOUTHERN PLAINS AND THE SOUTHEAST IN THE 8-14 DAY PERIOD, CONSISTENT WITH
MOST MODEL PRECIPITATION FORECASTS. HOWEVER, A CHANGING PATTERN AND INCREASING
DIFFERENCES BETWEEN MODEL FORECAST TOOLS LEADS TO A LARGE AREA OF SLIGHTLY
FAVORED NEAR NORMAL PRECIPITATION ACROSS MUCH OF THE NORTHERN CENTRAL CONUS,
OHIO VALLEY, AND MID-ATLANTIC. BELOW NORMAL PRECIPITATION IS SLIGHTLY FAVORED
OVER MUCH OF THE NORTHEASTERN CONUS, UNDER A PERSISTENT RIDGE AND ANOMALOUS
NORTHERLY FLOW. ABOVE NORMAL PRECIPITATION IS FAVORED ACROSS MOST OF HAWAII
EXCLUDING THE BIG ISLAND, CONSISTENT WITH THE PRECIPITATION CONSOLIDATION.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 30% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 30% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, WITH
EMERGING MODEL DIFFERENCES ON THE MID-LEVEL HEIGHT FORECAST WITH AN EVOLVING
PATTERN, AND WEAK SIGNALS IN THE PRECIPITATION TOOLS FOR MOST AREAS.
FORECASTER: D COLLINS
NOTES:
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 1991-2020 BASE PERIOD MEANS AS REFERENCE IN
THE CLIMATE OUTLOOKS.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON
OCTOBER 16.
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:
20090913 - 20090918 - 20010925 - 19670831 - 20060909
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:
20090914 - 20030905 - 20090909 - 19940919 - 20081003
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 26 - 30 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF N A IDAHO A A NEVADA A A
W MONTANA A N E MONTANA A B WYOMING A N
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A A N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A N OKLAHOMA N N
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA A B IOWA A B MISSOURI A N
ARKANSAS N A LOUISIANA A A WISCONSIN A B
ILLINOIS A N MISSISSIPPI A A MICHIGAN A B
INDIANA A N OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS A N 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 N A
AK ALEUTIAN A N AK WESTERN N A AK INT BSN B A
AK S INT N N AK SO COAST N N AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 28 - OCT 04, 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF N A IDAHO A A NEVADA A A
W MONTANA A N E MONTANA A N WYOMING A N
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A A N DAKOTA A N S DAKOTA A N
NEBRASKA A N KANSAS A N OKLAHOMA A N
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA A N IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA A A WISCONSIN A N
ILLINOIS A N MISSISSIPPI A A MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A A ALABAMA A A NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS A N
PENN A N NEW JERSEY A N W VIRGINIA A N
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A N S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE N A
AK ALEUTIAN A N AK WESTERN N A AK INT BSN N A
AK S INT A A AK SO COAST A A AK PNHDL N 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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