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FXUS06 KWBC 151907
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 15 2025
6-10 DAY OUTLOOK FOR SEP 21 - 25 2025
TODAY'S NUMERICAL MODELS ARE GENERALLY IN GOOD AGREEMENT IN DEPICTING AN
AMPLIFIED 500-HPA FLOW PATTERN ACROSS THE HIGHER LATITUDES OF NORTH AMERICA AND
SURROUNDING AREAS. THE PERIOD BEGINS WITH A DEEP TROUGH OVER THE EASTERN GULF
OF ALASKA, ANOMALOUS RIDGING OVER CENTRAL CANADA NEAR HUDSON BAY, AND ANOMALOUS
TROUGHING OVER THE WESTERN ATLANTIC SOUTH OF GREENLAND. FARTHER TO THE SOUTH, A
SHORTWAVE TROUGH IS FORECAST OFF THE COAST OF CALIFORNIA, WEAK RIDGING IS
PREDICTED OVER THE INTERIOR WEST, AND CYCLONIC FLOW IS FORECAST OVER THE
MISSISSIPPI VALLEY. AS TIME PROGRESSES, THE TROUGH OVER THE EASTERN GULF OF
ALASKA IS EXPECTED TO SLOWLY DRIFT SOUTHEASTWARD TO A POSITION JUST OFFSHORE OF
SOUTHEAST ALASKA. THE RIDGE OVER CENTRAL CANADA IS FORECAST TO PROGRESS
NORTHEASTWARD TOWARD BAFFIN ISLAND WHILE THE DOWNSTREAM TROUGH OVER THE WESTERN
ATLANTIC IS EXPECTED TO SLOWLY PROGRESS EASTWARD. ACROSS THE CONTIGUOUS U.S.
(CONUS), THE INITIAL SHORTWAVE TROUGH OFF THE CALIFORNIA COAST IS FORECAST TO
WEAKEN AS IT GETS SUBSUMED BY THE APPROACHING LARGER TROUGH MOVING SOUTHWARD
FROM THE GULF OF ALASKA. AS THIS TROUGH PUSHES SOUTHWARD OFF THE WEST COAST OF
NORTH AMERICA, ANOMALOUS RIDGING IS FORECAST TO DEVELOP INITIALLY OVER THE
INTERIOR WEST AND THEN SPREAD NORTHEASTWARD TO THE NORTHERN PLAINS. THE
DOWNSTREAM TROUGH OVER THE MISSISSIPPI VALLEY IS SLOWLY FORECAST TO PUSH
EASTWARD TOWARD THE EAST COAST. ACROSS HAWAII, NEAR NORMAL MID-LEVEL HEIGHTS
ARE GENERALLY FORECAST IN THE MEAN. HOWEVER, WEAKNESSES IN LOW-LATITUDE RIDGING
ARE NOTED IN VARIOUS MODEL SOLUTIONS, PARTICULARLY DURING THE EARLY TO MIDDLE
PORTIONS OF THE PERIOD.
ABOVE NORMAL TEMPERATURES ARE FAVORED ACROSS ALMOST THE ENTIRE CONTIGUOUS
UNITED STATES DUE TO PREDICTED WIDESPREAD NEAR TO ABOVE NORMAL HEIGHTS.
PROBABILITIES OF ABOVE NORMAL TEMPERATURES EXCEED 80 PERCENT ACROSS MUCH OF THE
NORTH-CENTRAL CONUS, CONSISTENT WITH PREDICTED RIDGING NEAR HUDSON BAY AND OVER
THE NORTHERN HIGH PLAINS. THE LEAST CONFIDENCE OF ABOVE NORMAL TEMPERATURES
(BETWEEN 33 AND 40 PERCENT) IS FORECAST FOR MUCH OF CALIFORNIA AS WELL AS FOR
PARTS OF THE EAST COAST. TELECONNECTIONS FROM MOST OF THE MAIN HIGH-LATITUDE
FEATURES FAVOR NEAR OR BELOW NORMAL TEMPERATURES FOR THE WEST COAST, OFFSETTING
WARMER DYNAMICAL MODEL GUIDANCE. IN THE CASE OF THE EASTERN SEABOARD, THE
COMBINATION OF RIDGING OVER HUDSON BAY AND A PREDICTED TROUGH OVER THE
SOUTHEAST FAVORS ANOMALOUS EASTERLY MID-LEVEL FLOW AND A MODERATING INFLUENCE
FROM THE ATLANTIC. A SLIGHT TILT TOWARD ABOVE NORMAL TEMPERATURES IS INDICATED
FOR EASTERN MAINLAND ALASKA DUE TO POTENTIAL WEAK OR TRANSIENT RIDGING. BELOW
NORMAL TEMPERATURES ARE MORE LIKELY FOR PARTS OF THE WESTERN MAINLAND,
CONSISTENT WITH TELECONNECTIONS FROM THE PREDICTED MEAN TROUGH POSITION NEAR
SOUTHEAST ALASKA. ABOVE NORMAL TEMPERATURES ARE LIKELY FOR THE WESTERN AND
CENTRAL HAWAIIAN ISLANDS, CONSISTENT WITH ABOVE NORMAL SEA SURFACE TEMPERATURES
(SSTS) IN THE ADJACENT PACIFIC.
AN ACTIVE PATTERN IS FAVORED FOR THE WESTERN CONUS DUE TO POTENTIAL RESIDUAL
TROPICAL MOISTURE OVER THE SOUTHWEST EARLY IN THE PERIOD COMBINED WITH ENHANCED
MOIST FLOW FROM THE PACIFIC FARTHER TO THE NORTH ACROSS THE PACIFIC NORTHWEST.
THE GREATEST CONFIDENCE OF ABOVE NORMAL PRECIPITATION IS ACROSS THE PACIFIC
NORTHWEST AND NORTHERN CALIFORNIA AS TELECONNECTIONS FROM THE UPSTREAM TROUGH
POSITION OVER THE EASTERN GULF OF ALASKA FAVORS A WET PATTERN. NEAR TO BELOW
NORMAL PRECIPITATION IS FAVORED ACROSS THE CENTRAL CONUS, CONSISTENT WITH MEAN
RIDGING PREDICTED OVER THE NORTHERN HIGH PLAINS. THE COVERAGE OF ENHANCED ABOVE
NORMAL PRECIPITATION PROBABILITIES ARE SIGNIFICANTLY REDUCED RELATIVE TO
YESTERDAY ACROSS THE CENTRAL CONUS AS MODELS ARE TRENDING STRONGER WITH THIS
RIDGE. ABOVE NORMAL PRECIPITATION IS FAVORED FOR THE SOUTHEASTERN QUADRANT OF
THE CONUS NORTHWARD TO THE OHIO VALLEY AND MID-ATLANTIC, AHEAD OF A MEAN TROUGH
FORECAST OVER THE MISSISSIPPI VALLEY. A TILT TOWARD ABOVE NORMAL PRECIPITATION
IS INDICATED FOR SOUTHEAST ALASKA AND PARTS OF EASTERN MAINLAND ALASKA,
ASSOCIATED WITH A PREDICTED SURFACE LOW NEAR THE SOUTH COAST. WEAKLY ENHANCED
PROBABILITIES OF ABOVE NORMAL PRECIPITATION ARE INDICATED FOR WESTERN AND
CENTRAL HAWAII, CONSISTENT WITH CONSOLIDATED CALIBRATED PRECIPITATION AMOUNTS
FROM THE GEFS AND ECMWF ENSEMBLES.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 20% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 50% 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
FAIR AGREEMENT AMONG TODAY’S ENSEMBLE MEANS.
8-14 DAY OUTLOOK FOR SEP 23 - 29 2025
DURING WEEK-2, A NEGATIVE NORTH AMERICAN OSCILLATION (NAO) PATTERN PREDOMINATES
AS ABOVE NORMAL MID-LEVEL HEIGHTS CONSOLIDATE NEAR BAFFIN ISLAND, PARTICULARLY
IN THE ECMWF ENSEMBLE MEAN. UNCERTAINTY ACROSS WESTERN NORTH AMERICA IS HIGH,
PARTICULARLY REGARDING THE EVOLUTION OF AN ANOMALOUS TROUGH FORECAST JUST OFF
THE COAST OF SOUTHEAST ALASKA EARLY IN THE PERIOD. AS TIME PROGRESSES, THE
ECMWF MEAN KEEPS THE TROUGH LOCATION IN PLACE WHILE THE GEFS AND CANADIAN MEANS
PUSH THIS THROUGH INLAND ACROSS THE WESTERN CONUS. DOWNSTREAM, HEIGHT FALLS ARE
PREDICTED ACROSS FIRST THE INTERIOR WEST AND EVENTUALLY THE NORTHERN PLAINS AS
EARLY RIDGING WEAKENS AND PROGRESSES EASTWARD. THE EASTWARD PROGRESSION OF
THIS WEAKENING RIDGE IS GENERALLY FORECAST TO PROMOTE MODEST HEIGHT RISES
ACROSS THE EASTERN SEABOARD, BUT UNCERTAINTY IS HIGH AS THE FORECASTED NEGATIVE
NAO WOULD TEND TO PRECLUDE RIDGE DEVELOPMENT OVER THE EAST COAST. FARTHER TO
THE SOUTH, MODELS GENERALLY DEPICT A WEAKNESS IN SUBTROPICAL RIDING NEAR THE
GULF COAST. CYCLONIC FLOW IS FORECAST OVER WESTERN MAINLAND ALASKA WITH THE
CANADIAN ENSEMBLE MEAN BY FAR DEPICTING THE STRONGEST TROUGH. MID-LEVEL RIDGING
IS FORECAST TO DEVELOP WELL TO THE NORTH OF HAWAII WITH MEAN NEAR NORMAL
HEIGHTS EXPECTED ACROSS THE ISLAND CHAIN.
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE ENTIRE CONUS WITH THE EXCEPTION
OF THE FAR WEST, CONSISTENT WITH PREDICTED NEAR TO ABOVE NORMAL MID-LEVEL
HEIGHTS AND LOW AMPLITUDE FLOW. THE GREATEST CONFIDENCE OF ABOVE NORMAL
TEMPERATURES (ABOVE 70 PERCENT CHANCE) IS FORECAST FOR THE NORTHERN PLAINS AND
UPPER MISSISSIPPI VALLEY, WHERE PREDICTED POSITIVE HEIGHT ANOMALIES ARE THE
GREATEST. NEAR NORMAL TEMPERATURES ARE FAVORED FOR THE FAR WEST DUE TO
UNCERTAINTIES SURROUNDING THE EVOLUTION OF A NEARBY TROUGH. ABOVE NORMAL
TEMPERATURES ARE FAVORED FOR PARTS OF EASTERN ALASKA DUE TO PREDICTED WEAK
RIDGING OVER ADJACENT NORTHWESTERN CANADA. BELOW NORMAL TEMPERATURES ARE
SLIGHTLY FAVORED FOR THE WESTERN MAINLAND, CONSISTENT WITH TELECONNECTIONS FROM
THE PREDICTED MEAN RIDGE NEAR BAFFIN ISLAND. ABOVE NORMAL TEMPERATURES ARE
FAVORED FOR THE WESTERN AND CENTRAL HAWAIIAN ISLANDS, CONSISTENT WITH POSITIVE
SST ANOMALIES IN THE ADJACENT PACIFIC.
AN ACTIVE PATTERN REMAINS LIKELY FOR THE NORTHWESTERN CONUS DUE TO PREDICTED
ENHANCED PACIFIC FLOW. PROBABILITIES OF ABOVE NORMAL PRECIPITATION EXCEED 60
PERCENT ALONG THE PACIFIC NORTHWEST COASTLINE. PROBABILITIES OF ABOVE NORMAL
PRECIPITATION ARE REDUCED RELATIVE TO 6 TO 10 DAY PERIOD ACROSS MUCH OF THE
REMAINDER OF THE WEST AS SUBTROPICAL RIDGING IS FORECAST TO RETREAT SOUTH INTO
NORTHERN MEXICO WITH TIME, TO A POSITION LESS FAVORABLE FOR AN ENHANCED
MONSOON. NEAR TO BELOW NORMAL PRECIPITATION IS MORE LIKELY ACROSS MUCH OF THE
CENTRAL CONUS, GREAT LAKES, AND EAST COAST DUE TO MULTIPLE AREAS OF PREDICTED
SURFACE HIGH PRESSURE. HOWEVER, A SLIGHT TILT TOWARD ABOVE NORMAL PRECIPITATION
IS INDICATED FOR THE GULF COAST AND LOWER MISSISSIPPI VALLEY DUE TO A PREDICTED
WEAKNESS IN SUBTROPICAL RIDGING NEAR THE AREA AND MODESTLY ENHANCED
SOUTHEASTERLY LOW-LEVEL FLOW FROM THE GULF. BELOW NORMAL PRECIPITATION IS
FAVORED FOR WESTERN MAINLAND ALASKA, CONSISTENT WITH PREDICTED OFFSHORE FLOW.
NEAR TO ABOVE NORMAL PRECIPITATION IS MORE LIKELY FOR EASTERN PARTS OF THE
STATE, ASSOCIATED WITH PREDICTED SURFACE LOW PRESSURE OVER THE GULF OF ALASKA.
WEAKLY ENHANCED PROBABILITIES OF ABOVE NORMAL PRECIPITATION ARE INDICATED FOR
WESTERN AND CENTRAL HAWAII, CONSISTENT WITH CONSOLIDATED CALIBRATED
PRECIPITATION AMOUNTS FROM THE GEFS AND ECMWF ENSEMBLES.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 20% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 50% 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, DUE TO
UNCERTAINTIES SURROUNDING THE EVOLUTION OF THE 500-HPA FLOW PATTERN ACROSS MUCH
OF THE FORECAST DOMAIN AS WELL AS WEAK OR CONFLICTING SIGNALS AMONG THE
PRECIPITATION GUIDANCE.
FORECASTER: SCOTT 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:
20090915 - 20010927 - 20090910 - 19960917 - 19620929
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:
20090911 - 20090916 - 20010926 - 20090906 - 19960915
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 21 - 25 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 N
UTAH A A ARIZONA A A COLORADO A N
NEW MEXICO A N N DAKOTA A B S DAKOTA A B
NEBRASKA A N KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS A N W TEXAS A N
MINNESOTA A B IOWA A N MISSOURI A N
ARKANSAS A A LOUISIANA A N WISCONSIN A B
ILLINOIS A N MISSISSIPPI A A MICHIGAN A N
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A B
MASS A N CONN A N RHODE IS N N
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 B N AK WESTERN N N AK INT BSN A N
AK S INT A N AK SO COAST A N AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 23 - 29 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON N A NRN CALIF N A
SRN CALIF N N IDAHO A A NEVADA A A
W MONTANA A A E MONTANA A A WYOMING A N
UTAH A N ARIZONA A N COLORADO A N
NEW MEXICO A B N DAKOTA A N S DAKOTA A N
NEBRASKA A N KANSAS A B OKLAHOMA A N
N TEXAS A N S TEXAS A A W TEXAS A B
MINNESOTA A N IOWA A N 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 N
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 N
FL PNHDL A A FL PENIN A A AK N SLOPE A N
AK ALEUTIAN N N AK WESTERN B B AK INT BSN A N
AK S INT A N AK SO COAST A N 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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