956
FXUS06 KWBC 221901
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT MON SEPTEMBER 22 2025
6-10 DAY OUTLOOK FOR SEP 28 - OCT 02, 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 NORTH-CENTRAL AND
NORTHEASTERN CONUS. NEGATIVE 500-HPA HEIGHT ANOMALIES ARE PREDICTED OVER THE
PACIFIC NORTHWEST IN ALL MODEL ENSEMBLE MEANS, RELATED TO THE AMPLIFIED TROUGH
OVER THE NORTHEAST PACIFIC. SHORTWAVE TROUGHS ARE PREDICTED OVER THE SOUTHWEST
AND THE SOUTHEAST AT THE START OF THE 6-10 DAY PERIOD BY ALL ENSEMBLE MODELS.
THE ECMWF PREDICTS A SLIGHTLY MORE AMPLIFIED TROUGH OVER THE SOUTHWEST RELATIVE
TO THE GEFS AND CANADIAN ENSEMBLE MEANS.
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 MOST OF MAINLAND ALASKA, EXCLUDING PARTS OF THE
WEST COAST, 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 80 PERCENT FOR PARTS OF THE NORTH-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 TO BELOW 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 ENHANCED PRECIPITATION AND CLOUDINESS. ABOVE NORMAL
TEMPERATURES ARE LIKELY ACROSS THE HAWAIIAN ISLANDS, CONSISTENT WITH THE
TEMPERATURE CONSOLIDATION.
BELOW NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR SOUTHWESTERN MAINLAND
ALASKA, UNDER ANOMALOUS NORTHERLY FLOW. ABOVE NORMAL PRECIPITATION IS SLIGHTLY
FAVORED FOR NORTHEASTERN MAINLAND ALASKA AND SOUTHEAST ALASKA, AHEAD OF 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 ARE INDICATED OVER THE SOUTHWEST,
UNDER A PREDICTED SHORTWAVE TROUGH. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED
ALONG THE SOUTHEAST COAST, CONSISTENT WITH CALIBRATED ECMWF AND GEFS
PRECIPITATION FORECASTS. BELOW NORMAL PRECIPITATION IS FAVORED FOR A LARGE AREA
OF THE NORTH-CENTRAL AND NORTHEASTERN 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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
GOOD AGREEMENT BETWEEN ENSEMBLE MODEL FORECASTS ON AN AMPLIFIED MID-LEVEL
HEIGHT PATTERN, OFFSET BY SOME DIFFERENCES AMONG TEMPERATURE AND PRECIPITATION
TOOLS WITH AN EVOLVING CIRCULATION PATTERN.
8-14 DAY OUTLOOK FOR SEP 30 - OCT 06, 2025
THERE IS INCREASING UNCERTAINTY AND DIFFERENCES 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 DURING 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. ALL ENSEMBLE MEANS
PREDICT PERSISTENCE OF POSITIVE 500-HPA HEIGHT ANOMALIES OVER THE CONUS THROUGH
WEEK 2, WITH INCREASING MID-LEVEL HEIGHTS OVER THE WEST. THE ECMWF PREDICTS
POSITIVE 500-HPA HEIGHT ANOMALIES OVER THE PACIFIC NORTHWEST IN THE 8-14 DAY
MEAN, WHILE THE GEFS PREDICTS SLIGHTLY NEGATIVE 500-HPA HEIGHT ANOMALIES OVER
THE REGION.
ABOVE NORMAL TEMPERATURES ARE FAVORED OVER THE ALEUTIAN ISLANDS, UNDER A
DEAMPLIFYING POSITIVE 500-HPA HEIGHT ANOMALY. AS THE MID-LEVEL CIRCULATION
PATTERN DEAMPLIFIES AND EVOLVES IN THE 8-14 DAY PERIOD, NEAR NORMAL
TEMPERATURES ARE FAVORED FOR MAINLAND ALASKA. NEAR NORMAL TEMPERATURES ARE
FAVORED FOR SOUTHEAST ALASKA IN WEEK 2, WITH INCONSISTENCY AMONG TEMPERATURE
TOOLS. ABOVE NORMAL TEMPERATURES ARE LIKELY ACROSS MOST OF THE 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 EASTERN MAINLAND ALASKA AND SOUTHEAST ALASKA,
CONSISTENT WITH MOST MODEL PRECIPITATION TOOLS. ABOVE NORMAL PRECIPITATION
CONTINUES TO BE SLIGHTLY FAVORED FOR NORTHERN CALIFORNIA AND THE PACIFIC
NORTHWEST, AHEAD OF A WEAKENING TROUGH OVER THE PACIFIC. ABOVE NORMAL
PRECIPITATION CONTINUES TO BE FAVORED FOR THE SOUTHWEST INTO THE CENTRAL
ROCKIES AND SOUTHERN PLAINS, CONSISTENT WITH THE CONSOLIDATION OF CALIBRATED
ECMWF AND GEFS PRECIPITATION FORECASTS. PROBABILITIES FOR ABOVE NORMAL
PRECIPITATION ARE SLIGHTLY ENHANCED FOR PARTS OF THE GULF AND SOUTHEAST
ATLANTIC COASTS IN THE 8-14 DAY PERIOD, CONSISTENT WITH THE CONSOLIDATION.
BELOW NORMAL PRECIPITATION IS SLIGHTLY FAVORED OVER MUCH OF THE NORTHEASTERN
CONUS, UNDER A PERSISTENT RIDGE AND POSITIVE 500-HPA HEIGHT ANOMALIES. ABOVE
NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR THE NORTHWESTERN HAWAIIAN ISLANDS,
WHILE BELOW NORMAL PRECIPITATION IS SLIGHTLY FAVORED OVER PARTS OF 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
OVERALL MODEL AGREEMENT ON AN EVOLVING CIRCULATION PATTERN, OFFSET BY
DIFFERENCES AMONG MODEL PRECIPITATION AND TEMPERATURE TOOLS IN SOME AREAS, 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:
20010925 - 20090911 - 19551005 - 20081005 - 19621002
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:
20010926 - 20090910 - 20081005 - 19870915 - 19551005
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 28 - OCT 02, 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 A NEVADA A A
W MONTANA A N E MONTANA A B WYOMING A N
UTAH A A ARIZONA N A COLORADO A A
NEW MEXICO N A N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A N OKLAHOMA A B
N TEXAS A N S TEXAS A A W TEXAS N A
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA A N WISCONSIN A B
ILLINOIS A B MISSISSIPPI A B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A N 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 N
FL PNHDL A N FL PENIN A N AK N SLOPE B N
AK ALEUTIAN A N AK WESTERN B B AK INT BSN B A
AK S INT B B AK SO COAST B B AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 30 - OCT 06, 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 N NEVADA A N
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 A 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 N WISCONSIN A N
ILLINOIS A N MISSISSIPPI A N MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A N ALABAMA A N 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 B
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 A
AK S INT N A AK SO COAST N 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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