734
FXUS06 KWBC 231924
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE SEPTEMBER 23 2025
6-10 DAY OUTLOOK FOR SEP 29 - OCT 03, 2025
DYNAMICAL MODELS ARE IN VERY GOOD AGREEMENT REGARDING AN AMPLIFIED 500-HPA
HEIGHT PATTERN ACROSS THE CONUS DURING THE 6-10 DAY PERIOD. ANOMALOUS RIDGING
IS FORECAST TO BE CENTERED ACROSS ONTARIO. TROUGHS ARE FORECAST ACROSS THE
NORTHEAST PACIFIC AND THE NORTH ATLANTIC. BY DAY-10, THE MID-LEVEL FLOW ACROSS
THE CONUS IS FORECAST TO BECOME MUCH MORE ZONAL COMPARED TO THE START OF THE
PERIOD, WITH TROUGHING OVER THE NORTHEAST PACIFIC RETROGRADING CLOSER TO
SOUTHERN ALASKA, WITH ANOTHER TROUGH AXIS POSSIBLY APPROACHING WESTERN ALASKA.
TODAY’S MANUAL 500-HPA HEIGHT BLEND FOR THE 6-10 DAY PERIOD DEPICTS
ABOVE-NORMAL HEIGHTS ACROSS MUCH OF THE CONUS, WITH THE LARGEST POSITIVE HEIGHT
ANOMALIES (+180 METERS) ACROSS THE NORTHERN GREAT LAKES. TIED TO TROUGHING,
BELOW-NORMAL HEIGHTS ARE FORECAST ACROSS THE PACIFIC NORTHWEST EXTENDING
THROUGH SOUTHERN MAINLAND AND SOUTHEAST ALASKA. NEAR- TO ABOVE-NORMAL HEIGHTS
ARE INDICATED ACROSS THE ALEUTIANS AND FAR NORTHERN AND WESTERN MAINLAND
ALASKA. MID-LEVEL HEIGHTS ARE FORECAST TO INCREASE ACROSS HAWAII FOLLOWING THE
PASSAGE OF SURFACE LOW PRESSURE TO THE NORTH PRIOR TO THE START OF THE PERIOD.
STRONG RIDGING OVER EASTERN AND CENTRAL NORTH AMERICA SUPPORTS ELEVATED
PROBABILITIES OF ABOVE-NORMAL TEMPERATURES ACROSS MOST OF THE CONUS.
PROBABILITIES EXCEED 80 PERCENT OVER PORTIONS OF THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY. DESPITE TROUGHING, ENHANCED PACIFIC FLOW COMBINED WITH
ABOVE-NORMAL SEA SURFACE TEMPERATURES (SSTS) OVER THE EASTERN PACIFIC SUPPORT
INCREASED CHANCES OF ABOVE-NORMAL TEMPERATURES OVER THE WEST, ALTHOUGH
PROBABILITIES ARE REDUCED COMPARED TO FURTHER EAST. ENHANCED PRECIPITATION AND
CLOUD COVER RESULT IN A FORECAST OF NEAR-NORMAL TEMPERATURES OVER PORTIONS OF
THE SOUTHWEST, WITH THE ECENS-BASED GUIDANCE COLDER COMPARED TO THE GEFS. NEAR-
TO BELOW-NORMAL TEMPERATURE CHANCES ARE INCREASED ACROSS MUCH OF ALASKA
(EXCLUDING THE ALEUTIANS WHERE ABOVE-NORMAL TEMPERATURES ARE MORE LIKELY) DUE
TO THE TREND TOWARD MORE TROUGHING ACROSS THE STATE AND WITH SUPPORT FROM THE
UNCALIBRATED ECENS AND GEFS, AND THE ECENS REFORECAST TOOL. ABOVE-NORMAL
TEMPERATURES ARE FORECAST FOR MOST OF HAWAII, WITH THE EXCEPTION OF PARTS OF
THE BIG ISLAND WHERE NEAR-NORMAL TEMPERATURES ARE FAVORED.
INCREASED PACIFIC FLOW FAVORS ABOVE-NORMAL PRECIPITATION ACROSS MUCH OF THE
WESTERN CONUS INTO THE NORTHERN AND CENTRAL PLAINS, WITH CHANCES EXCEEDING 50
PERCENT OVER THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA. CHANCES FOR
BELOW-NORMAL PRECIPITATION ARE INCREASED FROM THE SOUTHERN PLAINS THROUGH THE
MISSISSIPPI VALLEY, OHIO VALLEY, GREAT LAKES, AND NORTHEAST UNDERNEATH THE
MID-LEVEL RIDGE AND SURFACE HIGH PRESSURE. THERE IS GREATER UNCERTAINTY ACROSS
THE MID-ATLANTIC TIED TO POTENTIAL TROPICAL DEVELOPMENT ACROSS THE WESTERN
ATLANTIC. THE NATIONAL HURRICANE CENTER IS MONITORING TWO SEPARATE
DISTURBANCES, AND THEIR CLOSE PROXIMITY MAY BE IMPACTING HOW THE MODELS ARE
RESOLVING THESE SYSTEMS, AND WHETHER OR NOT BOTH DEVELOP INTO SEPARATE SYSTEMS
VERSUS ONLY ONE SYSTEM. THE DETERMINISTIC 0Z ECMWF AND ITS ENSEMBLE DEPICT TWO
SEPARATE SYSTEMS, WITH THE WESTERN-MOST LOW TRACKING ALONG THE EASTERN SEABOARD
INTO THE MID-ATLANTIC AROUND SEP 29-30. HOWEVER, THE DETERMINISTIC 12Z ECMWF IS
MUCH QUICKER TO RECURVE THE SYSTEM OFFSHORE. ADDITIONALLY, THE LAST SEVERAL
RUNS OF THE DETERMINISTIC GFS FAVOR ONLY THE EASTERN-MOST SYSTEM DEVELOPING BUT
ALSO REMAINING OFFSHORE, WITH NO DIRECT IMPACTS TO THE EAST COAST. AS A RESULT
OF THE UNCERTAINTY, NEAR-NORMAL PRECIPITATION IS FORECAST ACROSS PORTIONS OF
THE MID-ATLANTIC AND LOWER NORTHEAST. THERE IS BETTER TOOL AGREEMENT SUPPORTING
ENHANCED ABOVE-NORMAL PRECIPITATION CHANCES ACROSS THE SOUTHERN MID-ATLANTIC
AND SOUTHEAST. A TRANSITIONAL MID-LEVEL HEIGHT PATTERN ACROSS ALASKA AND SOME
DISCREPANCIES IN THE TOOLS FAVORS NEAR-NORMAL PRECIPITATION FORECAST FOR MUCH
OF ALASKA, WITH WEAK CHANCES FOR ABOVE-NORMAL PRECIPITATION FAVORED OVER
PORTIONS OF EASTERN AND SOUTHEASTERN ALASKA, CLOSER TO THE TROUGHING OVER THE
NORTHEAST PACIFIC. SURFACE LOW PRESSURE IS FORECAST TO THE NORTH OF HAWAII
PRIOR TO THE START OF THE PERIOD, WITH A DRYING TREND LIKELY FURTHER SOUTH. AS
A RESULT, A SLIGHT TILT TOWARD ENHANCED PROBABILITIES FOR ABOVE- (BELOW) NORMAL
PRECIPITATION IS FAVORED ACROSS KAUAI AND OAHU (THE BIG ISLAND).
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 MODEL AGREEMENT REGARDING THE MID-LEVEL HEIGHT PATTERN, OFFSET BY A TREND
TOWARD MORE ZONAL FLOW, AND UNCERTAINTY REGARDING TROPICAL ACTIVITY OVER THE
WESTERN ATLANTIC.
8-14 DAY OUTLOOK FOR OCT 01 - 07 2025
THE 0Z ECENS, GEFS, AND CMCE CONTINUE THE TREND TOWARD A LESS AMPLIFIED AND
MORE ZONAL 500-HPA HEIGHT PATTERN ACROSS NORTH AMERICA DURING THE WEEK-2
PERIOD. THE LARGEST HEIGHT ANOMALIES IN THE MANUAL BLEND ARE LARGELY DRIVEN BY
THE STRONGER AMPLIFICATION AT THE START OF THE PERIOD, ALTHOUGH THE MODELS
MAINTAIN NEAR- TO ABOVE-NORMAL HEIGHTS OVER THE CONUS THROUGHOUT THE PERIOD.
THEREFORE, THE MANUAL BLEND INDICATES ABOVE-NORMAL HEIGHTS ACROSS MUCH OF THE
CONUS, WITH THE LARGEST POSITIVE ANOMALIES (+90 METERS) ACROSS THE GREAT LAKES,
BUT WITH +30 METER ANOMALIES EXTENDING THROUGH MUCH OF THE GREAT BASIN AND
SOUTHWEST. CLOSER TO NORMAL HEIGHTS ARE DEPICTED ACROSS THE LOWER MISSISSIPPI
VALLEY AND SOUTHEAST FURTHER DISPLACED FROM THE INITIAL RIDGE CENTER AND TIED
TO AN INCREASE IN FRONTAL ACTIVITY. NEAR- TO BELOW-NORMAL HEIGHTS ARE PREDICTED
ACROSS MUCH OF SOUTHERN ALASKA AS TROUGHING BECOMES CONSOLIDATED OVER THE GULF
OF ALASKA, WITH ABOVE-NORMAL HEIGHTS OVER THE FAR NORTHERN MAINLAND. NEAR- TO
ABOVE-NORMAL HEIGHTS ARE FORECAST ACROSS HAWAII.
THE AMPLIFIED RIDGE EARLY IN WEEK-2 COMBINED WITH INCREASING PACIFIC FLOW
SUPPORTS ELEVATED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ACROSS THE CONUS
DURING THE PERIOD. AS IN THE 6-10 DAY PERIOD, THE LARGEST PROBABILITIES
(GREATER THAN 60 PERCENT) ARE ACROSS THE NORTHERN PLAINS AND UPPER MISSISSIPPI
VALLEY CONSISTENT WITH THE STRONGEST SIGNALS IN THE TOOLS. TROUGHING OVER THE
GULF OF ALASKA FAVORS INCREASING SOUTHERLY TO SOUTHWESTERLY FLOW ACROSS
SOUTHEASTERN MAINLAND ALASKA, WITH BOTH THE GEFS AND ECENS REFORECAST TOOLS
SUPPORTING INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES OVER THE REGION. THE
SIGNALS ARE LESS CLEAR OVER THE REMAINDER OF ALASKA. NEAR-NORMAL TEMPERATURES
ARE FORECAST FOR MUCH OF THE WESTERN AND NORTHERN MAINLAND WHERE THE ECENS
(GEFS) FAVORS BELOW- (ABOVE) NORMAL TEMPERATURES. THE UNCALIBRATED GUIDANCE
SUPPORTS ENHANCED NEAR- TO BELOW-NORMAL TEMPERATURE CHANCES ACROSS SOUTHEAST
ALASKA. ABOVE-NORMAL TEMPERATURE PROBABILITIES ARE INCREASED ACROSS HAWAII,
SUPPORTED BY THE CONSOLIDATED REFORECAST TOOL.
SIGNALS FOR PRECIPITATION ARE WEAK ACROSS THE CONUS DURING WEEK-2 AS THE
MID-LEVEL PATTERN BECOMES LESS AMPLIFIED, AND NO MAJOR FEATURES ARE APPARENT IN
THE MODELS AT THIS LEAD. THE ENHANCED PACIFIC FLOW PATTERN FORECAST TO DEVELOP
GENERALLY FAVORS NEAR- TO WEAKLY ABOVE-NORMAL PRECIPITATION PROBABILITIES
ACROSS MUCH OF THE WESTERN AND CENTRAL CONUS, WHICH IS SUPPORTED BY THE ECENS
AND GEFS REFORECAST TOOLS. A SLIGHT TILT TOWARD ENHANCED PROBABILITIES OF
BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS THE GREAT LAKES, NORTHERN OHIO
VALLEY, AND NORTHEAST TIED TO SURFACE HIGH PRESSURE. LINGERING IMPACTS OF THE
POTENTIAL TROPICAL LOW DISCUSSED IN THE 6-10 PERIOD ARE POSSIBLE EARLY IN
WEEK-2 RESULTING IN A FORECAST OF NEAR-NORMAL PRECIPITATION ACROSS THE NORTHERN
MID-ATLANTIC AND LOWER NORTHEAST, ALTHOUGH IT REMAINS NOTABLE THAT THE GFS/GEFS
ARE LESS ROBUST WITH THE POTENTIAL. THERE IS BETTER AGREEMENT ACROSS THE
SOUTHEAST AND FLORIDA WHERE CONTINUED FRONTAL ACTIVITY SUPPORTS AN UPTICK IN
ABOVE-NORMAL PRECIPITATION CHANCES. ENHANCED CHANCES FOR ABOVE-NORMAL
PRECIPITATION ARE FORECAST ACROSS SOUTHEASTERN ALASKA DURING WEEK-2 TIED TO
INCREASING ONSHORE FLOW AND SURFACE LOW PRESSURE OVER THE GULF OF ALASKA.
NEAR-NORMAL PRECIPITATION IS FORECAST ELSEWHERE ACROSS THE STATE. THE
PRECIPITATION FORECAST ACROSS HAWAII REMAINS VARIABLE WITH A SLIGHT TILT TOWARD
ENHANCED ABOVE- (BELOW) NORMAL PRECIPITATION ODDS OVER KAUAI (THE BIG ISLAND),
WITH NEAR-NORMAL IN BETWEEN.
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: AVERAGE, 3 OUT OF 5, DUE TO THE
MID-LEVEL PATTERN BECOMING MORE ZONAL DURING WEEK-2 AND GOOD AGREEMENT
REGARDING THE TEMPERATURE OUTLOOK, OFFSET BY WEAK SIGNALS FOR PRECIPITATION.
FORECASTER: THOMAS COLLOW
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:
20010926 - 19870918 - 19620929 - 19551006 - 19960919
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:
19870916 - 20010926 - 19620928 - 19551005 - 20081005
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 29 - OCT 03, 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 A E MONTANA A N WYOMING A A
UTAH A A ARIZONA N A COLORADO A A
NEW MEXICO A A N DAKOTA A N S DAKOTA A N
NEBRASKA A A KANSAS A A OKLAHOMA A B
N TEXAS A B S TEXAS A N W TEXAS A A
MINNESOTA A N 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 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 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 A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE N N
AK ALEUTIAN N N AK WESTERN B N AK INT BSN B N
AK S INT B N AK SO COAST N N AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 01 - 07 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A N
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 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 N
MINNESOTA A A IOWA A A MISSOURI A N
ARKANSAS A N LOUISIANA A N WISCONSIN A N
ILLINOIS A N MISSISSIPPI A N MICHIGAN A B
INDIANA A N OHIO A N 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 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 N
AK ALEUTIAN N N AK WESTERN N N AK INT BSN N N
AK S INT A N 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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