815
FXUS06 KWBC 251901
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT MON AUGUST 25 2025
6-10 DAY OUTLOOK FOR AUG 31 - SEP 04, 2025
AT THE START OF THE 6-10 DAY PERIOD, AN AMPLIFIED MID-LEVEL RIDGE WITH
ASSOCIATED POSITIVE 500-HPA HEIGHT ANOMALIES IS FORECAST ACROSS CANADA. AS THE
PERIOD PROGRESSES, THIS INITIAL RIDGING IS FAVORED TO WEAKEN IN MAGNITUDE, WITH
THE LARGEST POSITIVE HEIGHT ANOMALIES SHIFTING TO THE WEST OVER SOUTHERN
ALASKA, AND DISPLACING UPSTREAM TROUGHING INITIALLY PREDICTED OVER THE BERING
SEA. WHILE THE 0Z ECENS IS THE MOST ROBUST WITH RIDGING BUILDING OVER SOUTHEAST
ALASKA BY THE MIDDLE OF THE PERIOD, THE 0Z CMCE ALSO INDICATES THIS FEATURE,
ALTHOUGH AT A SLIGHTER WEAKER AMPLITUDE. THE 0Z GEFS IS THE WEAKEST, AND
DEPICTS A LOWER AMPLITUDE PATTERN OVERALL ACROSS NORTH AMERICA RELATIVE TO THE
OTHER MODELS BY DAY 10. TROUGHING IS FORECAST TO REMAIN ACROSS THE EASTERN HALF
OF THE CONUS, WITH SOME POTENTIAL FOR THIS FEATURE TO RETROGRADE WESTWARD IN
CONJUNCTION WITH THE STRONG RIDGE POTENTIALLY DEVELOPING OVER SOUTHEAST ALASKA.
TODAY’S MANUAL 500-HPA HEIGHT BLEND FOR THE 6-10 DAY PERIOD DEPICTS POSITIVE
HEIGHT ANOMALIES OVER MOST OF CANADA, ALTHOUGH THE HIGHEST POSITIVE HEIGHT
ANOMALIES (+180 METERS) ARE NOW INDICATED OVER THE GULF OF ALASKA. POSITIVE
HEIGHT ANOMALIES EXTEND THROUGHOUT MUCH OF MAINLAND ALASKA, SOUTHEAST ALASKA,
AND THE EASTERN ALEUTIANS, AS WELL AS INTO PARTS OF THE NORTHWESTERN AND
NORTH-CENTRAL CONUS. NEGATIVE HEIGHT ANOMALIES ARE DEPICTED FROM THE CENTRAL
PLAINS EASTWARD TO THE ATLANTIC COAST. NEGATIVE HEIGHT ANOMALIES ARE ALSO
FAVORED OVER THE WESTERN ALEUTIANS. A WEAK MID-LEVEL FLOW PATTERN IS PREDICTED
IN THE VICINITY OF HAWAII, WITH NEAR- TO SLIGHTLY ABOVE-NORMAL HEIGHTS FAVORED.
A COOLER AIR MASS IS FORECAST TO BE ENTRENCHED ACROSS THE EASTERN HALF OF THE
CONUS AT THE START OF THE PERIOD, WITH A STATIONARY FRONTAL BOUNDARY SETTLING
ACROSS THE GULF COAST AND THE FLORIDA PENINSULA. TEMPERATURE ANOMALIES OF -5 TO
-10 DEG F ARE PREDICTED OVER MANY AREAS, WHICH WILL LIKELY BRING AN EARLY TASTE
OF FALL AT THE START OF SEPTEMBER. CONVERSELY ACROSS THE WEST, ENHANCED CHANCES
FOR ABOVE-NORMAL TEMPERATURES ARE FAVORED DUE TO THE RIDGING ACROSS CANADA.
THERE REMAINS SOME UNCERTAINTY OVER THE FOUR CORNERS AND ROCKIES WHERE THE
ECENS (GEFS) IS COOLER (WARMER), RESULTING IN SLIGHTLY ENHANCED PROBABILITIES
OF NEAR-NORMAL TEMPERATURES. ABOVE-NORMAL TEMPERATURE CHANCES ARE INCREASED
OVER PORTIONS OF SOUTH TEXAS AND THE FLORIDA PENINSULA TO THE SOUTH OF THE
STATIONARY FRONTAL BOUNDARY. ABOVE-NORMAL TEMPERATURE CHANCES ARE INCREASED
OVER SOUTHERN AND EASTERN MAINLAND AND SOUTHEAST ALASKA CONSISTENT WITH THE
GEFS AND ECENS REFORECAST TOOLS AND ABOVE-NORMAL MID-LEVEL HEIGHTS. WEAKLY
ENHANCED PROBABILITIES OF BELOW-NORMAL TEMPERATURES ARE FORECAST OVER PARTS OF
THE ALEUTIANS UNDER MORE INFLUENCE FROM TROUGHING OVER THE BERING SEA EARLY IN
THE PERIOD. ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR NEARLY ALL OF HAWAII,
EXCLUDING SOUTHERN PARTS OF THE BIG ISLAND WHERE NEAR- TO BELOW-NORMAL
TEMPERATURES ARE FAVORED, DUE TO BELOW-NORMAL SEA SURFACE TEMPERATURES JUST TO
THE SOUTH OF THE ISLAND.
THE AFOREMENTIONED STATIONARY FRONT FAVORS ELEVATED ABOVE-NORMAL PRECIPITATION
CHANCES ACROSS THE GULF AND SOUTHEAST COASTS, THE FLORIDA PENINSULA, AND
EXTENDING BACK INTO THE FOUR CORNERS AND SOUTHERN PLAINS. TO THE NORTH OF THIS
BOUNDARY, UNDERNEATH SURFACE HIGH PRESSURE, NEAR- TO BELOW-NORMAL PRECIPITATION
CHANCES ARE INCREASED, WITH THE HIGHEST CHANCES FOR BELOW-NORMAL PRECIPITATION
OVER THE INTERIOR NORTHEAST SUPPORTED BY THE UNCALIBRATED AND REFORECAST GEFS
AND ECENS. WEAK TROUGHING OVER THE EAST PACIFIC UNDERCUTTING THE RIDGING TO THE
NORTH FAVORS SOME ENHANCED ONSHORE FLOW ACROSS THE WEST, WITH LOW PRECIPITATION
CLIMATOLOGIES RESULTING IN ELEVATED ABOVE-NORMAL PRECIPITATION PROBABILITIES,
BUT GENERALLY LOW ACTUAL PRECIPITATION AMOUNTS. TROUGHING INITIALLY OVER THE
BERING SEA FAVORS INCREASED CHANCES OF ABOVE-NORMAL PRECIPITATION OVER MUCH OF
MAINLAND ALASKA AND THE ALEUTIANS, WITH INCREASED BELOW-NORMAL PRECIPITATION
ODDS OVER SOUTHEAST ALASKA DUE TO MORE INFLUENCE FROM THE RIDGING OVER CANADA.
NEAR- TO BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS HAWAII.
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: AVERAGE, 3 OUT OF 5, DUE TO GOOD
MODEL AGREEMENT REGARDING THE MID-LEVEL HEIGHT PATTERN EARLY IN THE PERIOD,
OFFSET BY INCREASING UNCERTAINTY REGARDING A HIGH AMPLITUDE RIDGE DEVELOPING
NEAR SOUTHEAST ALASKA AND ITS DOWNSTREAM IMPACTS BY THE END OF THE PERIOD.
8-14 DAY OUTLOOK FOR SEP 02 - 08 2025
THE 0Z ECENS AND CMCE CONTINUE TO AMPLIFY RIDGING ACROSS SOUTHEAST ALASKA
DURING WEEK-2, WITH THE 0Z GEFS MAINTAINING A LOW AMPLITUDE MID-LEVEL PATTERN
ACROSS NORTH AMERICA. THIS RIDGING MAY LEAD TO AN AMPLIFICATION OF TROUGHING
DOWNSTREAM OVER THE CENTRAL CONUS WHICH IS DEPICTED IN THE 0Z ECENS AND
CONSISTENT WITH TELECONNECTIONS, BUT IS NOT SEEN IN THE 0Z GEFS OR CMCE
SOLUTIONS. A WEAK TROUGH MAY PERSIST OFF THE WEST COAST OF THE CONUS UNDERNEATH
THE POSITIVE HEIGHT ANOMALIES TO THE NORTH. TROUGHING ALSO REMAINS PREDICTED
OVER THE BERING SEA EARLY IN THE PERIOD, ALTHOUGH THIS FEATURE IS PREDICTED TO
FURTHER WEAKEN AS THE AFOREMENTIONED RIDGING BECOMES MORE DOMINANT. TODAY’S
MANUAL 500-HPA HEIGHT BLEND FOR WEEK-2 DEPICTS A +120 METER POSITIVE HEIGHT
ANOMALY CENTER ACROSS THE GULF OF ALASKA, WITH POSITIVE HEIGHT ANOMALIES NOW
COVERING NEARLY ALL OF ALASKA, AND +30 METER POSITIVE ANOMALIES EXTENDING INTO
PORTIONS OF THE NORTHWESTERN CONUS. NEAR- TO BELOW-NORMAL HEIGHTS REMAIN
FORECAST OVER MUCH OF THE EASTERN HALF OF THE CONUS, WITH CLOSER TO NORMAL
HEIGHTS OVER MOST OF THE WEST. NEAR-TO ABOVE-NORMAL HEIGHTS ARE FORECAST TO
PERSIST ACROSS HAWAII.
ENHANCED PROBABILITIES FOR BELOW-NORMAL TEMPERATURES ARE FORECAST FROM THE
CENTRAL PLAINS TO THE EASTERN SEABOARD, BUT PROBABILITIES ARE REDUCED COMPARED
TO THE 6-10 DAY PERIOD GIVEN THE UNCERTAINTY IN THE MID-LEVEL PATTERN
EVOLUTION. WARMER AIR MAY BEGIN TO MIGRATE EASTWARD, FAVORING INCREASING
CHANCES FOR NEAR- TO ABOVE-NORMAL TEMPERATURES OVER PARTS OF THE GREAT LAKES
AND NORTHEAST. ABOVE-NORMAL TEMPERATURE PROBABILITIES REMAIN ELEVATED ALONG
MOST OF THE GULF COAST AND OVER THE FLORIDA PENINSULA TO THE SOUTH OF A
STATIONARY FRONTAL BOUNDARY. THE GEFS AND ECENS REFORECAST TOOLS SUPPORT
ENHANCED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES OVER THE CONUS WEST OF THE
ROCKIES. DISCREPANCIES HIGHLIGHTED DURING THE 6-10 DAY PERIOD REMAIN, WITH
NEAR-NORMAL TEMPERATURES PREDICTED OVER PORTIONS OF THE ROCKIES AND FOUR
CORNERS DUE TO MODEL DIFFERENCES. TELECONNECTIONS WITH THE POSITIVE HEIGHT
ANOMALY CENTER OVER THE GULF OF ALASKA FAVOR BELOW-NORMAL TEMPERATURES OVER
PORTIONS OF THE GREAT PLAINS, WHICH IS ALSO REFLECTED IN THE ECENS FORECAST,
ALTHOUGH THE WEAKER GEFS FORECAST REDUCES CONFIDENCE. HIGH PROBABILITIES OF
ABOVE-NORMAL TEMPERATURES ARE HIGHLIGHTED OVER MUCH OF MAINLAND AND SOUTHEAST
ALASKA, WITH ELEVATED CHANCES OF NEAR- TO BELOW-NORMAL TEMPERATURES FAVORED
ACROSS THE ALEUTIANS. ABOVE-NORMAL TEMPERATURES REMAIN FAVORED OVER HAWAII.
NEAR- TO ABOVE-NORMAL PRECIPITATION CHANCES ARE ELEVATED ACROSS THE ENTIRE
CONUS, WITH HIGHER CHANCES FOR ABOVE-NORMAL (GREATER THAN 40 PERCENT) OVER
PORTIONS OF SOUTH FLORIDA AND THE SOUTHERN PLAINS TIED TO A STATIONARY FRONT,
AND THE NORTHWEST DUE TO SOME INCREASE IN ONSHORE FLOW AND LOW PRECIPITATION
CLIMATOLOGIES. ADDITIONAL FRONTAL ACTIVITY IS POSSIBLE OVER MUCH OF THE CENTRAL
AND EASTERN CONUS LEADING TO THE ODDS IN THE FORECAST TOOLS TILTING
ABOVE-NORMAL. EXPANDING RIDGING OVER THE GULF OF ALASKA FAVORS A NORTHWARD PUSH
OF THE HIGHEST CHANCES FOR ABOVE-NORMAL PRECIPITATION ACROSS NORTHERN MAINLAND
ALASKA, WITH BELOW-NORMAL PRECIPITATION MORE LIKELY OVER SOUTHEASTERN PORTIONS
OF THE STATE. NEAR- TO ABOVE-NORMAL PRECIPITATION IS FAVORED ACROSS HAWAII.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 25% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 35% 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
INCREASING UNCERTAINTY IN THE 500-HPA PATTERN EVOLUTION, AND WEAKENING SIGNALS
IN THE TEMPERATURE AND PRECIPITATION GUIDANCE BY THE END OF THE PERIOD.
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:
19940816 - 19930805 - 20040810 - 19560808 - 19940828
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:
19930804 - 19940816 - 20040810 - 19940828 - 19870829
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 31 - SEP 04, 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF N N IDAHO A A NEVADA A A
W MONTANA A A E MONTANA A A WYOMING N A
UTAH N A ARIZONA N A COLORADO B A
NEW MEXICO B A N DAKOTA A A S DAKOTA N A
NEBRASKA B A KANSAS B A OKLAHOMA B A
N TEXAS B A S TEXAS A A W TEXAS B A
MINNESOTA A A IOWA B A MISSOURI B A
ARKANSAS B A LOUISIANA B A WISCONSIN N N
ILLINOIS B N MISSISSIPPI B A MICHIGAN A B
INDIANA B N OHIO B B KENTUCKY B N
TENNESSEE B N ALABAMA B A NEW YORK B B
VERMONT B B NEW HAMP B B MAINE N B
MASS B B CONN B B RHODE IS B N
PENN B B NEW JERSEY B B W VIRGINIA B B
MARYLAND B N DELAWARE B N VIRGINIA B N
N CAROLINA B A S CAROLINA B A GEORGIA B A
FL PNHDL B A FL PENIN A A AK N SLOPE N A
AK ALEUTIAN A A AK WESTERN N A AK INT BSN A A
AK S INT A A AK SO COAST A A AK PNHDL A B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 02 - 08 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A N
SRN CALIF N N IDAHO A A NEVADA A A
W MONTANA A A E MONTANA N A WYOMING N A
UTAH N A ARIZONA N A COLORADO B A
NEW MEXICO N A N DAKOTA N A S DAKOTA B A
NEBRASKA B A KANSAS B A OKLAHOMA B A
N TEXAS B A S TEXAS A A W TEXAS B A
MINNESOTA N A IOWA B A MISSOURI B A
ARKANSAS B A LOUISIANA A A WISCONSIN N N
ILLINOIS B A MISSISSIPPI B A MICHIGAN A N
INDIANA N A OHIO N A KENTUCKY B A
TENNESSEE B A ALABAMA B A NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS N N CONN N N RHODE IS N N
PENN N N NEW JERSEY N N W VIRGINIA N A
MARYLAND N N DELAWARE N N VIRGINIA B A
N CAROLINA B A S CAROLINA B A GEORGIA B A
FL PNHDL A A FL PENIN A A AK N SLOPE N A
AK ALEUTIAN A N AK WESTERN A A AK INT BSN A A
AK S INT A N AK SO COAST A N AK PNHDL A B
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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