147
FXUS06 KWBC 181902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU SEPTEMBER 18 2025
6-10 DAY OUTLOOK FOR SEP 24 - 28 2025
COMPARED TO YESTERDAY, SOME DIFFERENCES HAVE EMERGED IN THE DYNAMICAL MODEL
GUIDANCE FOR THE 6-10 DAY FORECAST PERIOD. MOST NOTABLE IS THE SUBSTANTIALLY
LESS AMPLIFIED TROUGH ACROSS THE NORTHEAST PACIFIC IN THE 0Z ECENS. THIS IS
ALSO REFLECTED TO SOME DEGREE IN THE 0Z CMCE, WITH THE 0Z GEFS MAINTAINING THE
MORE AMPLIFIED TROUGH, AND IS MORE EXPANSIVE IN REGARDS TO NEGATIVE 500-HPA
HEIGHT ANOMALIES OVER THE WESTERN THIRD OF THE CONUS BY THE SECOND HALF OF THE
PERIOD. THE ECENS AND GEFS CONTINUE TO DEPICT ANOMALOUS RIDGING CENTERED ACROSS
THE NORTH-CENTRAL CONUS INTO CANADA. THESE MODELS ALSO INDICATE A GREATER
DEGREE OF SHORTWAVE TROUGHING DEVELOPING OVER THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST UNDERNEATH THE RIDGE AXIS. TODAY’S 6-10 DAY MANUAL HEIGHT BLEND
DEPICTS ABOVE-NORMAL HEIGHTS ACROSS THE NORTHERN HALF OF THE CONUS FROM THE
ROCKIES TO THE NORTHEAST. NEAR TO SLIGHTLY BELOW-NORMAL HEIGHTS ARE NOW
INDICATED ACROSS PARTS OF THE SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY, AND
SOUTHEAST. NEAR- TO BELOW-NORMAL HEIGHTS ARE ALSO FORECAST ACROSS THE NORTHWEST
AND EXTENDING THROUGH SOUTHEASTERN ALASKA. ADDITIONAL TROUGHING APPROACHING
WESTERN AND NORTHERN ALASKA LEADS TO NEAR-NORMAL HEIGHTS OVER MUCH OF THE
REMAINDER OF ALASKA, WITH THE EXCEPTIONS BEING THE ALEUTIANS AND THE FAR
NORTHEASTERN MAINLAND WHERE 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 SUPPORTED BY NEARLY ALL THE FORECAST GUIDANCE. THE HIGHEST PROBABILITIES
(GREATER THAN 70 PERCENT) ARE FAVORED ACROSS THE UPPER MIDWEST, CLOSEST TO THE
POSITIVE MID-LEVEL HEIGHT ANOMALY MAXIMUM. ALTHOUGH TROUGHING MOVING CLOSER TO
THE WEST COAST WOULD SUPPORT A COOLING TREND AS THE PERIOD PROGRESSES, THE
RELATIVELY WARMER START TO THE PERIOD COMBINED WITH WEAKER AMPLIFICATION OF
THIS TROUGH IN THE ECENS AND CMCE SUPPORT ENHANCED CHANCES FOR ABOVE-NORMAL
TEMPERATURES FOR THE PERIOD AS A WHOLE, BUT WITH REDUCED PROBABILITIES COMPARED
TO FURTHER EAST. THE INCREASE IN TROUGHING ACROSS THE SOUTH-CENTRAL CONUS
FAVORS REDUCED CHANCES FOR ABOVE-NORMAL TEMPERATURES, WITH NEAR-NORMAL
TEMPERATURES NOW MORE LIKELY OVER PORTIONS OF THE CENTRAL PLAINS AND ADJACENT
MISSISSIPPI VALLEY, DUE IN PART TO THE POSSIBILITY OF ENHANCED CLOUD COVER AND
PRECIPITATION. 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-NORMAL TEMPERATURES ARE
FORECAST ACROSS THE REMAINDER OF MAINLAND ALASKA, GIVEN WARMER (COOLER) SIGNALS
IN THE REFORECAST (UNCALIBRATED) TOOLS. ENHANCED CHANCES OF NEAR- TO
BELOW-NORMAL TEMPERATURES ARE INDICATED ACROSS SOUTHEAST ALASKA. 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 ABOVE-NORMAL PRECIPITATION. THE ECENS REFORECAST TOOL CONTINUES TO
SUPPORT ELEVATED CHANCES OF ABOVE-NORMAL PRECIPITATION DESPITE THE WEAKER
TROUGH, ALTHOUGH PROBABILITIES HAVE DECREASED IN THE UNCALIBRATED ECENS
COMPARED TO YESTERDAY. AS A RESULT, PROBABILITIES FOR ABOVE-NORMAL
PRECIPITATION ARE REDUCED TO 40-60 PERCENT IN TODAY’S FORECAST ACROSS MUCH OF
THE NORTHWEST INTO NORTHERN PARTS OF CALIFORNIA AND NEVADA. DOWNSTREAM, CLOSER
TO THE MEAN RIDGE AXIS, BELOW-NORMAL PRECIPITATION CHANCES ARE SLIGHTLY
INCREASED ACROSS THE UPPER MISSISSIPPI VALLEY AND NORTHERN GREAT LAKES, WITH
INCREASING PACIFIC FLOW FAVORING NEAR-NORMAL PRECIPITATION ACROSS THE NORTHERN
AND CENTRAL PLAINS. SHORTWAVE TROUGHING AND INCREASING WET SIGNALS IN THE GEFS
AND ECENS REFORECAST TOOLS SUPPORT ELEVATED CHANCES FOR ABOVE-NORMAL
PRECIPITATION ACROSS THE SOUTHERN PLAINS, EXTENDING NORTHEASTWARD THROUGH MUCH
OF THE EASTERN CONUS. THE 0Z ECENS DEPICTS A CYCLONIC SYSTEM DEVELOPING ACROSS
THE REGION EARLY IN THE PERIOD POTENTIALLY LEADING TO FURTHER PRECIPITATION
ENHANCEMENT. ABOVE-NORMAL PRECIPITATION CHANCES ARE INCREASED ACROSS MUCH OF
WESTERN AND SOUTHERN ALASKA AHEAD OF INCOMING TROUGHING. BELOW-NORMAL
PRECIPITATION CHANCES ARE ELEVATED ACROSS THE NORTHEASTERN MAINLAND.
ABOVE-NORMAL PRECIPITATION IS FAVORED ACROSS HAWAII.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 50% 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: AVERAGE, 3 OUT OF 5, DUE TO DECENT
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 26 - OCT 02, 2025
DURING WEEK-2, ANOMALOUS RIDGING REMAINS FORECAST ACROSS EASTERN CANADA, WITH
WEAK TROUGHS FAVORED ON EITHER SIDE OF THE RIDGE, ACROSS WESTERN NORTH AMERICA,
AND OVER THE NORTH ATLANTIC. THE 0Z GEFS IS MORE AMPLIFIED WITH THE TROUGH IN
THE WEST COMPARED TO THE 0Z ECENS AND CMCE RESULTING IN GREATER 500-HPA HEIGHT
FALLS ACROSS THE WEST DURING THE PERIOD. THE 0Z ECENS AND TO SOME DEGREE THE
GEFS DEPICT A GREATER DEGREE OF SHORTWAVE TROUGHING ACROSS THE SOUTH-CENTRAL
AND SOUTHEASTERN CONUS UNDERNEATH THE RIDGE EARLY IN THE PERIOD. LATER IN
WEEK-2, THE MID-LEVEL FLOW ACROSS THE CONUS IS PREDICTED TO BECOME MORE
LOW-AMPLITUDE AND ZONAL AS THE AFOREMENTIONED FEATURES WEAKEN. THE WEEK-2
MANUAL 500-HPA HEIGHT BLEND DEPICTS ABOVE-NORMAL HEIGHTS ACROSS MUCH OF THE
MIDWEST, GREAT LAKES, AND NORTHEAST. NEAR-NORMAL HEIGHTS ARE FAVORED ACROSS THE
SOUTHERN HALF OF THE CONUS. NEAR- TO SLIGHTLY 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.
WHILE THE GEFS SUPPORTS A COOLER FORECAST ACROSS THE WEST DUE TO ITS STRONGER
DEPICTION OF TROUGHING, THE ECENS IS COMPARATIVELY WARMER, RESULTING IN A
FORECAST OF NEAR-NORMAL. CLOSER TO THE PACIFIC COAST, PROBABILITIES FOR
ABOVE-NORMAL TEMPERATURES ARE INCREASED SUPPORTED BY THE DYNAMICAL MODELS AS
WELL AS WARM SSTS. THE GEFS AND ECENS REFORECAST TOOLS CONTINUE TO SUPPORT
INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES ACROSS PORTIONS OF SOUTHERN
ALASKA AND THE ALEUTIANS TIED TO ENHANCED SOUTHERLY FLOW. NEAR-NORMAL
TEMPERATURES ARE MORE LIKELY ACROSS THE REMAINDER OF MAINLAND ALASKA.
UNCALIBRATED GUIDANCE CONTINUES TO SUPPORT INCREASED CHANCES OF NEAR- TO
BELOW-NORMAL TEMPERATURES OVER SOUTHEAST ALASKA. ABOVE-NORMAL TEMPERATURES ARE
FAVORED FOR HAWAII, CONSISTENT WITH CONTINUED POSITIVE SST ANOMALIES OVER THE
ADJACENT PACIFIC.
INCREASING PACIFIC FLOW FAVORS BROADLY ENHANCED PROBABILITIES FOR ABOVE-NORMAL
PRECIPITATION ACROSS MOST OF THE CONUS. THE HIGHEST CHANCES (GREATER THAN 40
PERCENT) ARE OVER THE NORTHWEST AND NORTHERN PLAINS, AND OVER THE TENNESSEE
VALLEY TIED TO SHORTWAVE TROUGHING AND POSSIBLE SURFACE LOW PRESSURE AT THE
OUTSET OF THE PERIOD. NEAR-NORMAL PRECIPITATION IS FAVORED ACROSS THE GREAT
LAKES, NORTHERN OHIO VALLEY, AND NEW ENGLAND COINCIDING WITH INCREASED POSITIVE
500-HPA HEIGHT ANOMALIES. ENHANCED SOUTHERLY FLOW SUPPORTS INCREASED CHANCES OF
NEAR- TO ABOVE-NORMAL PRECIPITATION ACROSS ALASKA, SUPPORTED BY REFORECAST AND
UNCALIBRATED TOOLS. WEAKLY ENHANCED CHANCES OF ABOVE NORMAL PRECIPITATION ARE
INDICATED FOR MOST OF HAWAII, CONSISTENT WITH THE CONSOLIDATED FORECAST TOOL.
NEAR-NORMAL PRECIPITATION IS FORECAST ACROSS THE BIG ISLAND.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 30% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 50% 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: BELOW AVERAGE, 2 OUT OF 5, DUE TO
A SIMILAR 500-HPA PATTERN FROM THE 6-10 DAY PERIOD, BUT OFFSET DUE TO
DECREASING AMPLIFICATION AND 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
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:
20090914 - 20090909 - 20010928 - 20090919 - 20080929
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 - 20090908 - 20090918 - 20080929 - 20010927
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 24 - 28 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 A A COLORADO A N
NEW MEXICO A N N DAKOTA A N S DAKOTA A N
NEBRASKA A N KANSAS A A OKLAHOMA N A
N TEXAS A A S TEXAS A A W TEXAS A N
MINNESOTA A N IOWA A N MISSOURI A A
ARKANSAS N A LOUISIANA A A WISCONSIN A B
ILLINOIS A A MISSISSIPPI A A MICHIGAN A A
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
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 N A AK WESTERN N A AK INT BSN N N
AK S INT N A AK SO COAST A A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 26 - OCT 02, 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON N A NRN CALIF A A
SRN CALIF N A 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 A N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A N W TEXAS A N
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN A N
ILLINOIS A A MISSISSIPPI A A MICHIGAN A N
INDIANA A A 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 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 A A AK WESTERN N N AK INT BSN N N
AK S INT A A 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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