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FXUS06 KWBC 241902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT SUN AUGUST 24 2025
6-10 DAY OUTLOOK FOR AUG 30 - SEP 03, 2025
DURING THE 6-10 DAY FORECAST PERIOD, A BROADLY AMPLIFIED MID-LEVEL RIDGE WITH
ASSOCIATED POSITIVE 500-HPA HEIGHT ANOMALIES REMAINS FORECAST ACROSS CANADA,
WITH AN AREA OF TROUGHING FURTHER UPSTREAM OVER THE BERING SEA, ALIGNING WITH A
TREND TOWARD A POSITIVE PHASE OF THE PACIFIC-NORTH AMERICAN PATTERN (+PNA)
GOING INTO SEPTEMBER. COMPARED TO YESTERDAY, THERE IS A GREATER WESTWARD
EXTENSION OF POSITIVE HEIGHT ANOMALIES ACROSS THE GULF OF ALASKA, PARTICULARLY
IN THE GEFS. ALSO OF NOTE IS THAT TODAY’S 6Z GEFS IS WEAKER AND MORE OFFSHORE
WITH TROUGHING DEPICTED OVER THE EASTERN PACIFIC COMPARED TO THE 0Z RUN, AND
ALSO YESTERDAY’S GEFS SOLUTIONS, WHICH DEPICTED THIS TROUGHING CLOSER TO OR
ALONG THE WEST COAST OF THE CONUS. MODELS REMAIN IN GOOD AGREEMENT REGARDING
TROUGHING OVER THE EASTERN U.S. TODAY’S MANUAL 500-HPA HEIGHT BLEND FOR THE
6-10 DAY PERIOD DEPICTS POSITIVE HEIGHT ANOMALIES OVER MOST OF CANADA EXTENDING
INTO PARTS OF THE NORTHWESTERN AND NORTH-CENTRAL CONUS, AND OVER MUCH OF
MAINLAND ALASKA, SOUTHEAST ALASKA, AND THE ALASKA PENINSULA. NEGATIVE HEIGHT
ANOMALIES ARE DEPICTED FROM THE CENTRAL PLAINS EASTWARD TO THE ATLANTIC COAST.
NEGATIVE HEIGHT ANOMALIES ARE ALSO FAVORED OVER THE ALEUTIANS, INCREASING IN
MAGNITUDE FARTHER WEST. 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 OF AMERICA AND THE FLORIDA PENINSULA. THE WEATHER PREDICTION
CENTER IS PREDICTING NEGATIVE DAYTIME MAXIMUM TEMPERATURE ANOMALIES OF AT LEAST
-10 DEG F ACROSS SOME PARTS OF THE CENTRAL PLAINS AT THE OUTSET OF THE PERIOD.
WHILE THESE ANOMALIES ARE FAVORED TO MODERATE LATER IN THE PERIOD, THE PERIOD
AS A WHOLE IS STILL LIKELY TO TILT BELOW-NORMAL, JUSTIFYING INCREASED
BELOW-NORMAL TEMPERATURE PROBABILITIES (GREATER THAN 60 PERCENT) OVER THE
REGION. FURTHER EAST, TEMPERATURE ANOMALIES OF -5 TO -10 DEG F WILL LIKELY
BRING AN EARLY TASTE OF FALL IN TIME OF THE LABOR DAY HOLIDAY WEEKEND.
CONVERSELY ACROSS THE WEST, ENHANCED CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE
FAVORED, WITH THE 6Z GEFS COMING MORE IN LINE WITH THE WARMER ECENS AND CMCE
SOLUTIONS. THERE REMAINS SOME UNCERTAINTY OVER THE FOUR CORNERS 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. NEAR-TO 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 AND THE NORTHWESTERN MAINLAND. ABOVE-NORMAL TEMPERATURES
ARE FAVORED FOR NEARLY ALL OF HAWAII, EXCLUDING SOUTHERN PARTS OF THE BIG
ISLAND WHERE NEAR-NORMAL TEMPERATURES ARE FAVORED, SUPPORTED BY THE
CONSOLIDATED FORECAST TOOL.
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 GREAT LAKES AND OHIO VALLEY, SUPPORTED MOSTLY BY THE UNCALIBRATED AND
REFORECAST ECENS, AS WELL AS THE ANALOGS. TROUGHING NEAR THE WEST COAST FAVORS
AN INCREASE IN ONSHORE FLOW, ALTHOUGH THE SIGNALS ARE REDUCED COMPARED TO
YESTERDAY GIVEN A MORE OFFSHORE AND WEAKER TROUGH BEING DEPICTED IN THE
GUIDANCE, PARTICULARLY THE 6Z GEFS. WHILE MUCH OF THE WEST CONTINUES TO LEAN
TOWARD ABOVE-NORMAL PRECIPITATION AIDED IN PART BY LOW CLIMATOLOGIES, THE
PROBABILITIES ARE REDUCED COMPARED TO YESTERDAY. TROUGHING 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
ABOVE-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, PARTICULARLY IN REGARDS TO TEMPERATURES OVER
THE WESTERN U.S.
8-14 DAY OUTLOOK FOR SEP 01 - 07 2025
MID-LEVEL RIDGING AND POSITIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST TO PERSIST
ACROSS CANADA DURING WEEK-2. WHILE THE GEFS AND CMCE SOLUTIONS DEPICT THE
POSITIVE HEIGHT ANOMALY CENTER REMAINING ACROSS CENTRAL CANADA, THE ECENS
INDICATES THE LARGEST POSITIVE HEIGHT ANOMALIES BECOMING CENTERED MORE TO THE
WEST ACROSS SOUTHEAST ALASKA, AND WEAKER HEIGHT ANOMALIES AND SOME HINTS OF
TROUGHING DEVELOPING OVER CENTRAL AND EASTERN CANADA LATER IN THE PERIOD. THE
MID-LEVEL FLOW PATTERN ACROSS THE CONUS IS FORECAST TO DECREASE IN AMPLITUDE
DUE TO TROUGHING INITIALLY FORECAST OVER THE EAST WEAKENING. A WEAK TROUGH MAY
PERSIST OFF THE WEST COAST OF THE CONUS UNDERNEATH THE POSITIVE HEIGHT
ANOMALIES BUILDING TO THE NORTH, AND TROUGHING ALSO REMAINS PREDICTED OVER THE
BERING SEA, ALTHOUGH THIS FEATURE IS WEAKER IN MAGNITUDE COMPARED TO THE 6-10
DAY PERIOD. TODAY’S MANUAL 500-HPA HEIGHT BLEND FOR WEEK-2 DEPICTS TWO +90
METER POSITIVE HEIGHT ANOMALY CENTERS ACROSS CENTRAL CANADA AND SOUTHEAST
ALASKA, WITH +30 METER POSITIVE ANOMALIES EXTENDING INTO PORTIONS OF THE
NORTHWEST AND NORTHERN PLAINS. POSITIVE HEIGHT ANOMALIES ARE FORECAST
THROUGHOUT MOST OF ALASKA EXCLUDING THE CENTRAL AND WESTERN ALEUTIANS WHERE
CLOSER TO NORMAL HEIGHTS ARE FAVORED. NEAR- TO BELOW-NORMAL HEIGHTS ARE
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.
GIVEN THE DECREASING AMPLIFICATION IN THE MID-LEVEL HEIGHT PATTERN OVER THE
CONUS, THE RESULTANT TEMPERATURE FORECAST IS MORE UNCERTAIN. 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 AND ARE MAINLY TIED TO HIGHER CONFIDENCE EARLIER IN THE PERIOD.
WARMER AIR MAY ALSO BEGIN TO MIGRATE EASTWARD, FAVORING INCREASING CHANCES FOR
NEAR- TO ABOVE-NORMAL TEMPERATURES OVER MUCH OF THE NORTHERN TIER. 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. AS
DISCUSSED IN THE 6-10 DAY OUTLOOK, MODELS ARE LEANING MORE TOWARD A WARMER
SOLUTION ACROSS THE WEST AND THIS IS REFLECTED IN THE FORECAST. THERE IS MORE
UNCERTAINTY OVER PORTIONS OF THE SOUTHWEST DUE TO INCREASING EAST PACIFIC
TROPICAL MOISTURE, AND OVER THE ROCKIES DUE TO MODEL DIFFERENCES SIMILAR TO
THAT OF THE 6-10 DAY PERIOD, RESULTING IN NEAR-NORMAL BEING FAVORED OVER THESE
AREAS. 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.
A STATIONARY FRONT CONTINUES TO SUPPORT INCREASED CHANCES OF ABOVE-NORMAL
PRECIPITATION ACROSS THE COASTAL SOUTHEAST AND GULF COAST, AND EXTENDING BACK
THROUGH THE HIGH PLAINS AND FOUR CORNERS. TO THE NORTH OF THIS BOUNDARY, THE
ECENS IS DRIER COMPARED TO THE GEFS ACROSS THE EAST, WITH SOME UNCERTAINTY INTO
HOW QUICKLY MOISTURE ADVECTS INTO THE REGION AS THE TROUGHING WEAKENS.
NEAR-NORMAL PRECIPITATION IS GENERALLY FAVORED FOR MUCH OF THE INTERIOR EAST,
WITH A SLIGHT TILT TOWARD INCREASED ODDS FOR BELOW-NORMAL PRECIPITATION OVER
PARTS OF THE GREAT LAKES AND NORTHEAST. DESPITE THE LOW AMPLITUDE PATTERN,
ENHANCED ONSHORE FLOW ACROSS THE WEST COAST FAVORS ELEVATED ABOVE-NORMAL
PRECIPITATION PROBABILITIES OVER MUCH OF THE WEST, GIVEN LOW CLIMATOLOGIES THIS
TIME OF YEAR. CONTINUED TROPICAL CYCLONE ACTIVITY ACROSS THE EASTERN PACIFIC
MAY ALSO CONTRIBUTE TO ENHANCED MOISTURE OVER THE SOUTHWEST TOWARD THE END OF
THE PERIOD. ODDS FOR NEAR-TO ABOVE-NORMAL PRECIPITATION CONTINUE TO BE ELEVATED
OVER MUCH OF MAINLAND ALASKA AND THE ALEUTIANS ASSOCIATED WITH TROUGHING OVER
THE BERING SEA EARLY IN THE PERIOD. LARGER POSITIVE HEIGHT ANOMALIES DOWNSTREAM
SUPPORT INCREASED CHANCES FOR BELOW-NORMAL PRECIPITATION OVER SOUTHEAST ALASKA.
NEAR- TO ABOVE-NORMAL PRECIPITATION IS FAVORED ACROSS HAWAII.
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: BELOW AVERAGE, 2 OUT OF 5, DUE TO
DECREASING AMPLIFICATION OF THE 500-HPA PATTERN 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 - 19560808 - 19540830 - 19930804 - 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:
19930803 - 19940816 - 19940828 - 19560807 - 20040809
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 30 - SEP 03, 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A 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 N A
NEW MEXICO N 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 N A IOWA B N MISSOURI B N
ARKANSAS B A LOUISIANA B A WISCONSIN B B
ILLINOIS B N MISSISSIPPI B A MICHIGAN B B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE B N ALABAMA B N NEW YORK B B
VERMONT B B NEW HAMP B B MAINE B B
MASS B N CONN B N RHODE IS B N
PENN B B NEW JERSEY B N W VIRGINIA B B
MARYLAND B N DELAWARE B N VIRGINIA B N
N CAROLINA B N S CAROLINA B A GEORGIA B A
FL PNHDL B A 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 B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 01 - 07 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 A A COLORADO B A
NEW MEXICO N A N DAKOTA A A S DAKOTA N A
NEBRASKA B A KANSAS B A OKLAHOMA B A
N TEXAS N A S TEXAS A A W TEXAS N A
MINNESOTA N N IOWA B A MISSOURI B A
ARKANSAS B N LOUISIANA A A WISCONSIN N N
ILLINOIS B N MISSISSIPPI N A MICHIGAN A N
INDIANA N N OHIO N N KENTUCKY B N
TENNESSEE B N ALABAMA B N NEW YORK N B
VERMONT N N NEW HAMP N N MAINE N B
MASS N N CONN N N RHODE IS N N
PENN N N NEW JERSEY B N W VIRGINIA N N
MARYLAND B N DELAWARE B N VIRGINIA B N
N CAROLINA B N S CAROLINA B N GEORGIA B N
FL PNHDL N A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B A AK WESTERN A A AK INT BSN A A
AK S INT A A AK SO COAST A A 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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