837
FXUS06 KWBC 211901
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT SUN SEPTEMBER 21 2025
6-10 DAY OUTLOOK FOR SEP 27 - OCT 01, 2025
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, WITH SOME DIFFERENCES 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 AND THE BERING SEA. AN AMPLIFIED TROUGH IS PREDICTED FROM SOUTHEASTERN
MAINLAND ALASKA SOUTHWARD INTO THE NORTHEAST PACIFIC NEAR THE PACIFIC COAST OF
NORTH AMERICA. THIS PREDICTED TROUGH DEAMPLIFIES DURING THE PERIOD IN THE
ECMWF, 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 CENTRAL AND EASTERN CANADA AND THE NORTHERN CENTRAL AND
NORTHEASTERN CONUS. NEGATIVE 500-HPA HEIGHT ANOMALIES ARE PREDICTED OVER THE
PACIFIC NORTHWEST IN ALL MODEL ENSEMBLE MEANS, WHILE THE ECMWF PREDICTS WEAKER
NEGATIVE 500-HPA HEIGHT ANOMALIES RELATIVE TO THE GEFS AND CANADIAN ENSEMBLE
MEANS. A SHORTWAVE TROUGH IS PREDICTED OVER THE OHIO AND TENNESSEE VALLEYS AT
THE START OF THE 6-10 DAY PERIOD BY THE GEFS AND ECMWF ENSEMBLES, WHICH
DEAMPLIFIES DURING DAYS 7 AND 8.
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, WITH PROBABILITIES FOR ABOVE NORMAL EXCEEDING 70 PERCENT FOR
A LARGE AREA OF THE NORTHERN CENTRAL CONUS. 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 SOME
MODEL TOOLS INDICATE THE POSSIBILITY OF BELOW NORMAL 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. BELOW NORMAL
PRECIPITATION IS SLIGHTLY FAVORED FOR PARTS SOUTHWESTERN MAINLAND ALASKA AND
ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR NORTHEASTERN MAINLAND
ALASKA, RELATED TO THE PREDICTED TROUGH OVER THE 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 ALONG THE EAST COAST FROM FLORIDA TO COASTAL NEW
ENGLAND, CONSISTENT WITH THE CONSOLIDATION. BELOW NORMAL PRECIPITATION IS
FAVORED FOR A LARGE AREA OF THE NORTHERN CENTRAL CONUS, UNDER THE PREDICTED
RIDGE AND PERSISTENT POSITIVE 500-HPA HEIGHT ANOMALIES. 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 ON AN AMPLIFIED MID-LEVEL
HEIGHT PATTERN, OFFSET BY DIFFERENCES AMONG TEMPERATURE AND PRECIPITATION TOOLS
FOR SOME AREAS AND AN EVOLVING CIRCULATION PATTERN.
8-14 DAY OUTLOOK FOR SEP 29 - OCT 05, 2025
SOME DIFFERENCES APPEAR IN THE GEFS, ECMWF AND CANADIAN 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. A POSITIVE 500-HPA HEIGHT
ANOMALY IS CENTERED TO THE SOUTH OF THE CENTRAL ALEUTIAN ISLANDS IN ENSEMBLE
MEANS IN WEEK 2. THE GEFS, ECMWF AND CANADIAN ENSEMBLE MEANS PREDICT
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
PROGRESSES OVER THE BERING SEA. THE GEFS PREDICTS PERSISTENCE OF A MORE
AMPLIFIED TROUGH AND NEGATIVE 500-HPA HEIGHT ANOMALIES OVER THE NORTHEAST
PACIFIC RELATIVE TO THE ECMWF MODEL. 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.
AS THE MID-LEVEL CIRCULATION PATTERN DEAMPLIFIES AND UNCERTAINTY INCREASES,
NEAR NORMAL TEMPERATURES ARE SLIGHTLY FAVORED FOR MOST OF MAINLAND ALASKA IN
THE 8-14 DAY PERIOD. ABOVE NORMAL TEMPERATURES ARE FAVORED OVER THE ALEUTIAN
ISLANDS, UNDER A DEAMPLIFYING POSITIVE 500-HPA HEIGHT ANOMALY, AND FOR THE
SOUTHWESTERN AND SOUTHERN COASTS OF MAINLAND ALASKA, CONSISTENT WITH THE
CONSOLIDATION OF CALIBRATED GEFS AND ECMWF TEMPERATURE FORECASTS. NEAR NORMAL
TEMPERATURES ARE NOW FAVORED FOR SOUTHEAST ALASKA IN WEEK 2, WITH INCONSISTENCY
AMONG TEMPERATURE TOOLS. ABOVE NORMAL TEMPERATURES ARE LIKELY ACROSS THE ENTIRE
CONUS IN THE 8-14 DAY PERIOD, UNDER PERSISTENT POSITIVE 500-HPA HEIGHT
ANOMALIES AND A NEAR ZONAL PACIFIC FLOW. ABOVE NORMAL TEMPERATURES ARE LIKELY
ACROSS HAWAII IN THE 8-14 DAY PERIOD, CONSISTENT WITH THE TEMPERATURE
CONSOLIDATION.
A CHANGING PATTERN AND INCREASING DIFFERENCES BETWEEN MODEL FORECAST TOOLS
LEADS TO WEAK SIGNALS IN THE 8-14 DAY PRECIPITATION OUTLOOK. WITH A WEAKENING
TROUGH OVER THE ALASKA REGION, PROBABILITIES FOR ABOVE NORMAL PRECIPITATION
REMAIN SLIGHTLY ENHANCED FOR SOUTHEASTERN MAINLAND ALASKA AND SOUTHEAST ALASKA,
CONSISTENT WITH MOST MODEL PRECIPITATION TOOLS. FOR THE CONUS, ABOVE NORMAL
PRECIPITATION CONTINUES TO BE SLIGHTLY FAVORED FOR MOST OF THE WEST FROM THE
PACIFIC COAST TO THE ROCKY MOUNTAINS AND PARTS OF THE SOUTHERN HIGH PLAINS,
AHEAD OF A WEAKENING TROUGH OVER THE PACIFIC. NEAR NORMAL PRECIPITATION IS
FAVORED FOR CLIMATOLOGICALLY ARID AREAS OF CALIFORNIA. PROBABILITIES FOR ABOVE
NORMAL PRECIPITATION ARE SLIGHTLY ENHANCED FOR SOUTH TEXAS, THE GULF COAST, AND
PARTS OF THE SOUTHEAST IN THE 8-14 DAY PERIOD, CONSISTENT WITH MOST MODEL
PRECIPITATION FORECASTS. BELOW NORMAL PRECIPITATION IS SLIGHTLY FAVORED OVER
MUCH OF THE MIDWEST AND NORTHEAST, UNDER A PERSISTENT RIDGE AND POSITIVE
500-HPA HEIGHT ANOMALIES. 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
AGREEMENT ON THE OVERALL CIRCULATION PATTERN AMONG MODEL FORECASTS, OFFSET BY
DIFFERENCES AMONG MODEL PRECIPITATION AND TEMPERATURES TOOLS IN SOME AREAS, AN
EVOLVING PATTERN, AND WEAK SIGNALS IN THE PRECIPITATION TOOLS.
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:
20090910 - 20010925 - 20090915 - 19621002 - 19670901
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:
20090915 - 20090910 - 20030905 - 20010926 - 19670903
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 27 - OCT 01, 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A A IDAHO A N 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 B OKLAHOMA A B
N TEXAS A N S TEXAS A A W TEXAS A A
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA A N WISCONSIN A B
ILLINOIS A B MISSISSIPPI A N MICHIGAN A B
INDIANA A B OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA A N NEW YORK A N
VERMONT A N NEW HAMP A A MAINE A N
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 A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE N N
AK ALEUTIAN A N AK WESTERN B N AK INT BSN B N
AK S INT N B AK SO COAST N B AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 29 - OCT 05, 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A N IDAHO A A NEVADA A A
W MONTANA A N E MONTANA A N WYOMING A A
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 N S TEXAS A A W TEXAS A A
MINNESOTA A N IOWA A B MISSOURI A B
ARKANSAS A N LOUISIANA A N WISCONSIN A B
ILLINOIS A B MISSISSIPPI A N MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A N
TENNESSEE A N ALABAMA A A NEW YORK A B
VERMONT A B NEW HAMP A B MAINE A B
MASS A B CONN A B RHODE IS A B
PENN A B NEW JERSEY A B W VIRGINIA A B
MARYLAND A B DELAWARE A B 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 N
AK ALEUTIAN A N AK WESTERN N N AK INT BSN N N
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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