406
FXUS06 KWBC 171902
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 17 2025
6-10 DAY OUTLOOK FOR SEP 23 - 27 2025
DYNAMICAL MODELS REMAIN IN GOOD AGREEMENT IN DEPICTING AN AMPLIFIED 500-HPA
HEIGHT PATTERN ACROSS THE HIGHER LATITUDES OF NORTH AMERICA AND SURROUNDING
AREAS DURING THE 6-10 DAY FORECAST PERIOD. ANOMALOUS TROUGHING IS FORECAST TO
SHIFT FROM THE EASTERN GULF OF ALASKA TO THE WEST COAST OF THE CONTIGUOUS U.S.
(CONUS), WITH A SECOND WEAK TROUGH MOVING INTO PARTS OF WESTERN AND NORTHERN
MAINLAND ALASKA LATER IN THE PERIOD. DOWNSTREAM, ENHANCED RIDGING IS FAVORED TO
SHIFT FROM THE NORTH-CENTRAL CONUS INTO EASTERN CANADA. WEAK TROUGHING AND
ASSOCIATED CYCLONIC FLOW IS FORECAST TO PERSIST OVER PORTIONS OF THE LOWER
MISSISSIPPI VALLEY AND SOUTHEAST. TODAY’S 6-10 DAY MANUAL HEIGHT BLEND DEPICTS
NEAR- TO ABOVE-NORMAL HEIGHTS ACROSS MUCH OF THE CONUS, WITH THE LARGEST
POSITIVE ANOMALIES (+120 METERS) OVER NORTH DAKOTA AND NORTHERN MINNESOTA.
CLOSER TO NORMAL HEIGHTS ARE PREDICTED ALONG THE EAST COAST AND EXTENDING BACK
THROUGH THE SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY, AND SOUTHEAST,
UNDERNEATH RESIDUAL TROUGHING. BELOW-NORMAL HEIGHTS ARE FORECAST ACROSS THE
PACIFIC NORTHWEST AND EXTENDING THROUGH SOUTHEASTERN ALASKA. ELSEWHERE ACROSS
ALASKA, NEAR- TO SLIGHTLY ABOVE-NORMAL HEIGHTS ARE FAVORED. NEAR- TO
ABOVE-NORMAL HEIGHTS ARE FORECAST ACROSS HAWAII AS RIDGING BECOMES CENTERED TO
THE NORTH OF THE ISLANDS.
INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE FAVORED ACROSS THE ENTIRE
CONUS GIVEN RIDGING PROGRESSING ACROSS THE WESTERN AND CENTRAL PARTS OF THE
COUNTRY. THE HIGHEST PROBABILITIES (GREATER THAN 80 PERCENT) ARE FAVORED ACROSS
THE UPPER MIDWEST. ALTHOUGH TROUGHING MOVING CLOSER TO THE WEST COAST WOULD
SUPPORT A COOLING TREND AS THE PERIOD PROGRESSES, THE RELATIVELY WARMER OUTSET
OF THE PERIOD FAVORS ABOVE-NORMAL TEMPERATURES FOR THE PERIOD AS A WHOLE, BUT
WITH REDUCED PROBABILITIES COMPARED TO FURTHER EAST. NEAR-NORMAL HEIGHTS
COMBINED WITH A FRONTAL SYSTEM, AND RELATIVELY WEAKER SIGNALS IN THE
UNCALIBRATED MODELS AND ANALOGS ALSO SUPPORT REDUCED PROBABILITIES FOR
ABOVE-NORMAL TEMPERATURES ACROSS THE SOUTH-CENTRAL AND SOUTHEASTERN CONUS. THE
GEFS AND ECENS REFORECAST TOOLS SUPPORT INCREASED ODDS FOR ABOVE-NORMAL
TEMPERATURES ACROSS SOUTHEASTERN ALASKA, TIED TO ENHANCED SOUTHERLY FLOW AHEAD
OF THE INCOMING TROUGH. NEAR- TO BELOW-NORMAL TEMPERATURES ARE FORECAST ACROSS
SOUTHEAST AND WESTERN ALASKA, CLOSER TO THE UPSTREAM AND DOWNSTREAM TROUGHS.
ABOVE-NORMAL TEMPERATURES ARE LIKELY FOR THE HAWAIIAN ISLANDS, CONSISTENT WITH
ABOVE-NORMAL SEA SURFACE TEMPERATURES (SSTS) IN THE ADJACENT PACIFIC.
TROUGHING APPROACHING THE WEST COAST OF THE CONUS SUPPORTS INCREASING ONSHORE
FLOW AND PRECIPITATION BEGINNING AROUND THE MIDDLE OF THE PERIOD. THE HIGHEST
CHANCES FOR ABOVE-NORMAL PRECIPITATION (GREATER THAN 60 PERCENT) ARE POSTED
ACROSS PARTS OF THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA TIED TO
TELECONNECTIONS FROM THE UPSTREAM TROUGH FURTHER SUPPORTING A WET PATTERN.
DOWNSTREAM, CLOSER TO THE MEAN RIDGE AXIS, BELOW-NORMAL PRECIPITATION CHANCES
ARE INCREASED ACROSS MUCH OF THE EASTERN ROCKIES, NORTHERN AND CENTRAL PLAINS,
AND INTO THE UPPER AND MIDDLE MISSISSIPPI VALLEY AND GREAT LAKES. ENHANCED
FRONTAL ACTIVITY AND CYCLONIC FLOW SUPPORT ELEVATED CHANCES FOR ABOVE-NORMAL
PRECIPITATION ACROSS THE SOUTHERN PLAINS, EXTENDING NORTHEASTWARD THROUGH PARTS
OF THE OHIO AND TENNESSEE VALLEYS. NEAR-NORMAL PRECIPITATION IS FAVORED
THROUGHOUT THE NORTHEAST AND ALONG THE EAST COAST. NEAR- TO BELOW-NORMAL
PRECIPITATION ODDS ARE INCREASED ACROSS MAINLAND ALASKA IN BETWEEN TWO TROUGHS.
WEAK PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION ARE HIGHLIGHTED ACROSS PARTS
OF THE ALEUTIANS AND SOUTHEAST ALASKA. ABOVE-NORMAL PRECIPITATION IS FAVORED
ACROSS HAWAII.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 35% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 45% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 20% 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 AMONG DYNAMICAL MODELS REGARDING THE 500-HPA PATTERN EVOLUTION,
OFFSET BY SOME UNCERTAINTY REGARDING THE AMPLITUDE OF TROUGHING PREDICTED ALONG
THE WEST COAST OF THE CONUS.
8-14 DAY OUTLOOK FOR SEP 25 - OCT 01, 2025
DURING WEEK-2, ANOMALOUS RIDGING REMAINS FORECAST ACROSS EASTERN CANADA, WITH
TROUGHS FAVORED ON EITHER SIDE OF THE RIDGE, ACROSS WESTERN NORTH AMERICA, AND
OVER THE NORTH ATLANTIC. THE TROUGHING ACROSS THE WEST IS ANTICIPATED TO SPREAD
FURTHER INLAND ACROSS THE CONUS, ALTHOUGH THE 0Z ECENS AND CMCE WEAKEN THE
FEATURE, WITH THE 0Z GEFS BEING MORE AMPLIFIED AND RESULTING IN GREATER 500-HPA
HEIGHT FALLS ACROSS THE WEST DURING THE PERIOD. THE TROUGH OVER THE NORTH
ATLANTIC MAY BECOME INFLUENCED BY THE EVENTUAL TRACK OF TROPICAL STORM
GABRIELLE AS CURRENT MODELS INDICATE THE POSSIBILITY OF THIS SYSTEM BECOMING A
LARGE POST-TROPICAL CYCLONE IN THE NORTH ATLANTIC BY WEEK-2. THE WEEK-2 MANUAL
500-HPA HEIGHT BLEND DEPICTS ABOVE-NORMAL HEIGHTS ACROSS MUCH OF THE MIDWEST,
GREAT LAKES, AND INTERIOR NORTHEAST. NEAR-NORMAL HEIGHTS ARE FAVORED ACROSS THE
IMMEDIATE EAST COAST AND THROUGHOUT MUCH OF THE SOUTHERN TIER OF THE CONUS.
NEAR- TO BELOW-NORMAL HEIGHTS ARE FORECAST OVER MUCH OF MAINLAND AND SOUTHEAST
ALASKA AND THE NORTHWESTERN CONUS TIED TO THE INITIAL TROUGH AND A SECOND
TROUGH FORECAST TO MOVE INTO PARTS OF WESTERN AND NORTHERN MAINLAND ALASKA.
NEAR-NORMAL HEIGHTS ARE PREDICTED ACROSS HAWAII AS RIDGING TO THE NORTH OF THE
ISLANDS BEGINS TO WEAKEN.
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE INCREASED ACROSS THE CONUS FROM
THE ROCKIES EASTWARD UNDERNEATH RIDGING AND SUPPORTED BY MOST FORECAST TOOLS.
THE HIGHEST PROBABILITIES (GREATER THAN 70 PERCENT) ARE FAVORED ACROSS PORTIONS
OF THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES. INCREASED ODDS FOR
BELOW-NORMAL TEMPERATURES ARE FAVORED ACROSS THE WEST TIED TO ENHANCED
TROUGHING, ALTHOUGH UNCERTAINTY REGARDING THE AMPLITUDE OF THE TROUGHING
PRECLUDES HIGHER PROBABILITIES. THE GEFS AND ECENS REFORECAST TOOLS CONTINUE TO
SUPPORT INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES ACROSS SOUTHEASTERN
MAINLAND ALASKA TIED TO ENHANCED SOUTHERLY FLOW. HOWEVER, NEAR-TO BELOW-NORMAL
TEMPERATURES CHANCES ARE INCREASED ACROSS MUCH OF THE REMAINDER OF MAINLAND
ALASKA AND SOUTHEAST ALASKA DUE TO MORE INFLUENCE FROM TROUGHS OVER THE
NORTHEAST PACIFIC AND UPSTREAM ACROSS NORTHERN AND WESTERN ALASKA. ABOVE-NORMAL
TEMPERATURES ARE FAVORED FOR HAWAII, CONSISTENT WITH CONTINUED POSITIVE SST
ANOMALIES OVER THE ADJACENT PACIFIC.
AN ACTIVE PATTERN REMAINS LIKELY FOR THE NORTHWESTERN CONUS INTO THE NORTHERN
PLAINS DUE TO TROUGHING AND ASSOCIATED ENHANCED PACIFIC FLOW. PROBABILITIES OF
ABOVE-NORMAL PRECIPITATION EXCEED 50 PERCENT ACROSS THE PACIFIC NORTHWEST AND
NORTHERN CALIFORNIA AND DECREASE FURTHER EAST. BELOW-NORMAL PRECIPITATION
CHANCES ARE ENHANCED ACROSS THE GREAT LAKES, NORTHERN OHIO VALLEY, AND INTERIOR
NORTHEAST COINCIDING WITH INCREASED POSITIVE 500-HPA HEIGHT ANOMALIES.
LINGERING CYCLONIC FLOW SUPPORTS A SLIGHT TILT TOWARD INCREASED ABOVE-NORMAL
PRECIPITATION CHANCES ACROSS MUCH OF THE SOUTHERN TIER OF THE CONUS.
NEAR-NORMAL PRECIPITATION IS FORECAST FOR MAINLAND ALASKA DUE TO CONFLICTING
SIGNALS IN THE FORECAST TOOLS AND THE INCOMING TROUGHING PREDICTED TO BE FAIRLY
WEAK. SLIGHT TILTS TOWARD ENHANCED ABOVE-NORMAL PRECIPITATION PROBABILITIES
REMAIN POSTED ACROSS PORTIONS OF THE ALEUTIANS AND SOUTHEAST ALASKA. WEAKLY
ENHANCED CHANCES OF ABOVE NORMAL PRECIPITATION ARE INDICATED FOR HAWAII,
CONSISTENT WITH THE CONSOLIDATED FORECAST TOOL.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 35% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 45% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 20% 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 A
SIMILAR 500-HPA PATTERN FROM THE 6-10 DAY PERIOD, BUT OFFSET DUE TO WEAKENING
PROBABILITIES AND SOME CONFLICTING SIGNALS IN THE MODEL GUIDANCE, PARTICULARLY
ACROSS THE WESTERN CONUS AND ALASKA.
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
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:
20090914 - 20090909 - 20010928 - 20090919 - 20080928
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:
20090913 - 20090918 - 20090908 - 20010927 - 20060902
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 23 - 27 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 B WYOMING A B
UTAH A A ARIZONA A A COLORADO A B
NEW MEXICO A B N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A B OKLAHOMA A N
N TEXAS A A S TEXAS A A W TEXAS A N
MINNESOTA A B IOWA A B MISSOURI A N
ARKANSAS A A LOUISIANA A A WISCONSIN A B
ILLINOIS A N MISSISSIPPI A A MICHIGAN A B
INDIANA A N OHIO A N 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 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 A
FL PNHDL A A FL PENIN A N AK N SLOPE B B
AK ALEUTIAN N A AK WESTERN B N AK INT BSN N N
AK S INT N N AK SO COAST A N AK PNHDL B N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 25 - OCT 01, 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF N A
SRN CALIF N N IDAHO N A NEVADA N A
W MONTANA A A E MONTANA A A WYOMING A A
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A N N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS A A W TEXAS A N
MINNESOTA A A IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA A A WISCONSIN A B
ILLINOIS A B MISSISSIPPI A N MICHIGAN A B
INDIANA A B OHIO A N KENTUCKY A N
TENNESSEE A A 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 N GEORGIA A N
FL PNHDL A A FL PENIN A A AK N SLOPE N N
AK ALEUTIAN N N AK WESTERN B N AK INT BSN N N
AK S INT N N AK SO COAST A N AK PNHDL B N
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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