535
FXUS06 KWBC 101902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED SEPTEMBER 10 2025
6-10 DAY OUTLOOK FOR SEP 16 - 20 2025
THE ECMWF, GEFS AND CANADIAN ENSEMBLE MODELS BROADLY AGREE ON THE 500-HPA
HEIGHT PATTERN OVER NORTH AMERICA AND SURROUNDING REGIONS DURING THE 6-10 DAY
PERIOD, WITH ONLY MINOR VARIATIONS AMONG THE MODELS IN TERMS OF AMPLITUDE AND
PHASE OF PREDICTED WAVE FEATURES. THE MANUAL HEIGHT BLEND IS BASED ON ENSEMBLE
MEANS, WEIGHING THE ECMWF MODEL GREATER DUE TO RECENT MODEL ANOMALY CORRELATION
SKILL. THE MANUAL BLEND SHOWS A TROUGH AND ASSOCIATED NEGATIVE 500-HPA HEIGHT
ANOMALIES OVER THE NORTH PACIFIC TO THE SOUTH OF THE EASTERN ALEUTIAN ISLANDS
AND THE ALASKA PENINSULA IN THE 6-10 DAY PERIOD MEAN. MODELS PREDICT WESTWARD
RETROGRESSION OF THE TROUGH AND NEGATIVE 500-HPA HEIGHT ANOMALIES FROM THE GULF
OF ALASKA EARLY IN THE PERIOD TO SOUTH OF THE EASTERN ALEUTIANS BY THE MIDDLE
OF THE PERIOD, FOLLOWED BY RAPID DEAMPLIFICATION. AN AMPLIFIED RIDGE IS
PREDICTED ACROSS CANADA IN THE 6-10 DAY PERIOD, EXTENDING INTO THE NORTHERN
CENTRAL CONTIGUOUS UNITED STATES (CONUS). IN THE MANUAL BLEND OF MODEL
FORECASTS, POSITIVE 500-HPA HEIGHT ANOMALIES ARE PREDICTED ACROSS MOST OF THE
CONUS IN THE 6-10 DAY PERIOD, WHILE WEAK TROUGHING AND NEAR ZERO MID-LEVEL
HEIGHT ANOMALIES ARE PREDICTED OVER THE SOUTHEAST. NEAR TO SLIGHTLY BELOW
NORMAL 500-HPA HEIGHTS ARE PREDICTED ACROSS HAWAII.
BELOW NORMAL TEMPERATURES ARE FAVORED FOR PORTIONS OF NORTHWESTERN MAINLAND
ALASKA UNDER ANOMALOUS NORTHERLY MID-LEVEL FLOW, WHILE ABOVE NORMAL
TEMPERATURES ARE MORE LIKELY FOR SOUTHERN AND EASTERN MAINLAND ALASKA AND
SOUTHEAST ALASKA UNDER MEAN POSITIVE 500-HPA HEIGHT ANOMALIES AND SOUTHERLY
FLOW. IN THE 6-10 DAY PERIOD, ABOVE NORMAL TEMPERATURES ARE LIKELY ACROSS MOST
OF THE CONUS EXCLUDING PARTS OF THE MIDDLE ATLANTIC, INFLUENCED BY THE
AMPLIFIED RIDGE AND POSITIVE 500-HPA HEIGHT ANOMALIES, SUPPORTED BY MOST OF THE
DYNAMICAL TEMPERATURE FORECAST TOOLS. NEAR NORMAL TEMPERATURES ARE FAVORED FOR
PARTS OF THE MIDDLE ATLANTIC IN THE 6-10 DAY PERIOD, RELATED TO THE PREDICTED
TROUGH AND WEAK 500-HPA HEIGHT ANOMALIES. ABOVE NORMAL TEMPERATURES ARE LIKELY
FOR HAWAII, CONSISTENT WITH THE CONSOLIDATION OF CALIBRATED ECMWF AND GEFS
FORECASTS AND ABOVE AVERAGE SEA SURFACE TEMPERATURES ACROSS MUCH OF THE REGION.
NEAR TO BELOW NORMAL PRECIPITATION IS FAVORED FOR PARTS OF WESTERN MAINLAND
ALASKA, UNDER ANOMALOUS NORTHERLY FLOW. ABOVE NORMAL PRECIPITATION IS FAVORED
FOR THE REMAINDER OF MAINLAND ALASKA AS WELL AS SOUTHEAST ALASKA, AHEAD OF A
PREDICTED TROUGH. AS MID-LEVEL HEIGHTS RISE OVER THE WESTERN CONUS,
PRECIPITATION IS PREDICTED TO DECREASE LEADING TO ENHANCED PROBABILITIES OF
BELOW NORMAL PRECIPITATION OVER PARTS OF WESTERN WASHINGTON, WESTERN OREGON,
NORTHERN CALIFORNIA, AND WESTERN NEVADA. ABOVE NORMAL PRECIPITATION IS FAVORED
IN THE 6-10 DAY PERIOD FOR MUCH OF THE INTERIOR WEST, INCLUDING THE SOUTHWEST,
THE NORTHERN ROCKIES, THE HIGH PLAINS, AND THE UPPER AND MIDDLE MISSISSIPPI
VALLEY, CONSISTENT WITH MOST MODEL FORECAST TOOLS AND THE CONSOLIDATION. BELOW
NORMAL PRECIPITATION IS FAVORED FOR EAST TEXAS, THE LOWER MISSISSIPPI VALLEY,
THE OHIO VALLEY, THE GREAT LAKES REGION, AND NORTHERN NEW ENGLAND, UNDER
ANOMALOUS NORTHERLY FLOW AHEAD OF THE PREDICTED RIDGE AND CONSISTENT WITH MOST
MODEL PRECIPITATION FORECASTS. PROBABILITIES FOR ABOVE NORMAL PRECIPITATION ARE
SLIGHTLY ENHANCED FOR THE FLORIDA PENINSULA IN THE 6-10 DAY PERIOD, CONSISTENT
WITH THE PRECIPITATION CONSOLIDATION. ABOVE NORMAL PRECIPITATION IS FAVORED FOR
THE HAWAIIAN ISLANDS, CONSISTENT WITH THE AUTO BLEND OF FORECAST TOOLS AND THE
PRECIPITATION CONSOLIDATION.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 6Z 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 OF AN AMPLIFIED MID-LEVEL
HEIGHT PATTERN, OFFSET BY SOME DIFFERENCES AMONG TEMPERATURE AND PRECIPITATION
FORECAST TOOLS FOR SOME AREAS.
8-14 DAY OUTLOOK FOR SEP 18 - 24 2025
ENSEMBLE MEAN FORECASTS FOR THE 500-HPA CIRCULATION PATTERN OVER NORTH AMERICA
REMAIN IN GENERAL AGREEMENT AND A TRANSITION IN THE 500-HPA PATTERN IS WELL
UNDERWAY ACROSS MUCH OF THE COUNTRY DURING THE 8-14 DAY PERIOD. AS TIME
PROGRESSES, THE PATTERN EVOLVES AND SOMEWHAT DEAMPLIFIES. A WEAK TROUGH
PERSISTS OVER THE EASTERN ALEUTIAN ISLANDS BUT DEAMPLIFIES DURING THE 8-14 DAY
PERIOD IN ALL ENSEMBLE MEAN FORECASTS. AN AMPLIFIED RIDGE AND ASSOCIATED
POSITIVE 500-HPA HEIGHT ANOMALIES PERSIST OVER CANADA THROUGH THE 8-14 DAY
PERIOD, WITH POSITIVE 500-HPA HEIGHT ANOMALIES EXTENDING SOUTHWARD ACROSS MOST
OF THE CONUS. A WEAK TROUGH AND SLIGHTLY NEGATIVE 500-HPA HEIGHT ANOMALIES
PERSIST OVER THE SOUTHEASTERN CONUS IN THE 8-14 DAY PERIOD MANUAL BLEND WITH
SOME VARIATIONS AMONG THE CANADIAN, ECMWF AND GEFS ENSEMBLE MEANS. GENERALLY
NEAR TO BELOW NORMAL HEIGHTS ARE FORECAST FOR HAWAII THROUGHOUT THE PERIOD.
ABOVE NORMAL TEMPERATURES ARE LIKELY OVER A LARGER AREA OF MAINLAND AND
SOUTHEAST ALASKA IN THE 8-14 DAY PERIOD, EXCLUDING PARTS OF NORTHWESTERN
MAINLAND ALASKA, AS THE PREDICTED TROUGH AND NEGATIVE 500-HPA HEIGHT ANOMALIES
TO THE SOUTH OF THE STATE DEAMPLIFY AND POSITIVE 500-HPA HEIGHT ANOMALIES
INCREASE IN MAGNITUDE AND EXTENT ACROSS MAINLAND ALASKA. ABOVE NORMAL
TEMPERATURES ARE FAVORED ACROSS THE ENTIRE CONUS, UNDER POSITIVE 500-HPA HEIGHT
ANOMALIES. PROBABILITIES FAVORING ABOVE NORMAL TEMPERATURES REACH 60% FOR PARTS
OF THE LOWER MISSISSIPPI VALLEY, THE TENNESSEE VALLEY, THE OHIO VALLEY, AND THE
GREAT LAKES REGION, SUPPORTED BY MOST OF THE TEMPERATURE FORECAST TOOLS. ABOVE
NORMAL TEMPERATURES ARE LIKELY FOR HAWAII, CONSISTENT WITH THE TEMPERATURE
CONSOLIDATION AND ABOVE AVERAGE SEA SURFACE TEMPERATURES AROUND THE
NORTHWESTERN ISLANDS.
NEAR NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR PARTS OF NORTHWESTERN
MAINLAND ALASKA UNDER PRIMARILY ANOMALOUS NORTHERLY FLOW IN THE EVOLVING
CIRCULATION PATTERN. ABOVE NORMAL PRECIPITATION CONTINUES TO BE FAVORED FOR THE
REMAINDER OF MAINLAND ALASKA AND SOUTHEAST ALASKA IN THE 8-14 DAY PERIOD,
CONSISTENT WITH MOST DYNAMICAL MODEL FORECASTS. NEAR TO ABOVE NORMAL
PRECIPITATION IS FAVORED FOR MOST OF THE WESTERN AND CENTRAL CONUS (EXCEPT FOR
WESTERN WASHINGTON AND WESTERN OREGON, WHERE BELOW NORMAL PRECIPITATION IS
FAVORED UNDER POSITIVE 500-PA HEIGHT ANOMALIES) IN WEEK 2, CONSISTENT WITH THE
PRECIPITATION CONSOLIDATION AND MOST MODEL TOOLS. BELOW NORMAL PRECIPITATION IS
SLIGHTLY FAVORED FOR MAINE, UNDER ABOVE NORMAL 500-HPA HEIGHTS AND THE
PREDICTED RIDGE. A TILT TOWARDS DRY FOR WEEK-2 ACROSS PARTS OF THE LOWER
MISSISSIPPI VALLEY AND THE TENNESSEE VALLEY BASED ON THE UNCALIBRATED 7-DAY
ECENS AND ANALOGS. ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR FLORIDA,
CONSISTENT WITH THE CONSOLIDATION. ABOVE NORMAL PRECIPITATION IS SLIGHTLY
FAVORED FOR THE HAWAIIAN ISLANDS, CONSISTENT WITH THE AUTO FORECAST BLEND.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 30% OF TODAY'S 6Z 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: NEAR AVERAGE, 3 OUT OF 5, DUE TO
GOOD OVERALL AGREEMENT ON THE MID-LEVEL HEIGHT FORECAST, OFFSET BY A
DEAMPLIFYING PATTERN AND WEAK SIGNALS IN THE PRECIPITATION TOOLS FOR MANY AREAS.
FORECASTER: LUKE H
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
SEPTEMBER 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:
19980920 - 20070913 - 19950924 - 19950908 - 19940827
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:
19980919 - 19510903 - 19950907 - 20070912 - 19940828
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 16 - 20 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A B
SRN CALIF A A IDAHO A A NEVADA A A
W MONTANA A A E MONTANA A A WYOMING A A
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A A N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A N
N TEXAS A N S TEXAS A N W TEXAS A A
MINNESOTA A A IOWA A A MISSOURI A N
ARKANSAS A N LOUISIANA A N WISCONSIN A A
ILLINOIS A N MISSISSIPPI A N MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA A N NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS N N
PENN A N NEW JERSEY A N W VIRGINIA A N
MARYLAND A N DELAWARE N N VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A A AK N SLOPE N A
AK ALEUTIAN N A AK WESTERN N A AK INT BSN A A
AK S INT A A AK SO COAST A A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 18 - 24 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A N NRN CALIF A A
SRN CALIF A A IDAHO A A NEVADA A A
W MONTANA A A E MONTANA A A WYOMING A A
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A A N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A N S TEXAS A N W TEXAS A A
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A N LOUISIANA A N WISCONSIN A A
ILLINOIS A A MISSISSIPPI A N MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA A N 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 N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE N A
AK ALEUTIAN A N AK WESTERN A A AK INT BSN A A
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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