719
FXUS06 KWBC 101918
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE SEPTEMBER 10 2024
6-10 DAY OUTLOOK FOR SEP 16 - 20 2024
THERE IS GOOD AGREEMENT BETWEEN THE 0Z ECMWF, GEFS AND CANADIAN ENSEMBLE MEAN
500-HPA HEIGHT FORECASTS, ON A PERSISTENT CIRCULATION PATTERN ACROSS NORTH
AMERICA. DYNAMICAL MODELS PREDICT A TROUGH CENTERED TO THE WEST OF ALASKA, AN
EXTENSION OF THE TROUGH SOUTHEASTWARD OVER WESTERN CANADA INTO THE WESTERN
CONTIGUOUS U.S. (CONUS), A RIDGE OVER EASTERN CANADA AND THE NORTHEASTERN
CONUS, AND WEAK NEGATIVE 500-HPA HEIGHT ANOMALIES AND A TROUGH OVER THE
SOUTHEASTERN CONUS. DYNAMICAL MODELS GENERALLY PREDICT PERSISTENCE OF THIS
PATTERN THROUGH THE 6-10 DAY PERIOD WITH WEAKENING ANOMALIES ASSOCIATED WITH
THE TROUGH OVER WESTERN NORTH AMERICA AROUND THE END OF THE PERIOD.
BELOW NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF THE EASTERN ALEUTIANS AND
THE WEST COAST OF MAINLAND ALASKA, UNDER A PREDICTED TROUGH. NEAR NORMAL
TEMPERATURES ARE FAVORED FOR MUCH OF SOUTHERN MAINLAND ALASKA AND SOUTHEAST
ALASKA, WHERE TEMPERATURE TOOLS DISAGREE. ABOVE NORMAL TEMPERATURES ARE LIKELY
FOR MOST OF NORTHERN MAINLAND ALASKA, UNDER ANOMALOUS SOUTHERLY FLOW. BELOW
NORMAL TEMPERATURES ARE LIKELY ACROSS THE WESTERN CONUS FROM THE COAST TO THE
ROCKY MOUNTAINS, UNDER A PREDICTED TROUGH. ABOVE NORMAL TEMPERATURES ARE LIKELY
FOR MOST OF THE REMAINDER OF THE CONUS, UNDER A PREDICTED RIDGE AND CONSISTENT
WITH DYNAMICAL MODEL TEMPERATURE FORECASTS. PROBABILITIES EXCEED 80 PERCENT FOR
ABOVE NORMAL TEMPERATURES FOR MUCH OF THE NORTH-CENTRAL CONUS, UNDER LARGE
POSITIVE 500-HPA HEIGHT ANOMALIES. NEAR NORMAL IS FAVORED FOR PARTS OF THE
SOUTHEAST WHERE DYNAMICAL MODEL TEMPERATURE TOOLS DISAGREE. ABOVE NORMAL
TEMPERATURES ARE FAVORED FOR HAWAII, CONSISTENT WITH THE TEMPERATURE
CONSOLIDATION.
ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR MOST OF ALASKA, UNDER AND
AHEAD OF A PREDICTED TROUGH AND CONSISTENT WITH DYNAMICAL MODEL PRECIPITATION
FORECASTS. ABOVE NORMAL PRECIPITATION IS LIKELY FOR THE NORTHWESTERN CONUS FROM
THE PACIFIC NORTHWEST INTO THE NORTHERN ROCKIES, AHEAD OF THE PREDICTED TROUGH.
ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED ACROSS MUCH OF THE WESTERN AND
CENTRAL CONUS, CONSISTENT WITH THE PRECIPITATION CONSOLIDATION. ABOVE NORMAL
PRECIPITATION IS FAVORED FOR PARTS OF THE SOUTHEAST COAST, UNDER WEAK NEGATIVE
500-HPA HEIGHT ANOMALIES. NEAR NORMAL PRECIPITATION IS FAVORED ACROSS MUCH OF
THE SOUTH-CENTRAL CONUS, WHERE PRECIPITATION TOOLS ARE INCONSISTENT. SMALL
AREAS OF SLIGHTLY ENHANCED PROBABILITIES FOR BELOW NORMAL PRECIPITATION ARE
FORECAST FOR PARTS OF SOUTHWEST AND THE CENTRAL GULF COAST, WHERE PRECIPITATION
TOOLS ARE CONSISTENT. BELOW NORMAL PRECIPITATION IS FAVORED FOR MUCH OF THE
NORTHEASTERN CONUS, UNDER THE PREDICTED RIDGE. ABOVE NORMAL PRECIPITATION IS
SLIGHTLY FAVORED FOR HAWAII, CONSISTENT WITH DYNAMICAL MODEL PRECIPITATION
FORECASTS.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 35% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 25% 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 THE DYNAMICAL MODEL HEIGHT FORECASTS AND TOOLS AND
DAY-TO-DAY RUN CONSISTENCY, OFFSET BY DIFFERENCES IN TEMPERATURE AND
PRECIPITATION TOOLS FOR SOME AREAS, SUCH AS PRECIPITATION FORECASTS FOR THE
SOUTH-CENTRAL CONUS AND TEMPERATURE FORECASTS FOR PARTS OF THE SOUTHEAST.
8-14 DAY OUTLOOK FOR SEP 18 - 24 2024
DYNAMICAL MODEL FORECASTS FROM THE ECMWF, GEFS AND CANADIAN ENSEMBLE MEANS
REMAIN IN GOOD AGREEMENT ON THE LARGE SCALE 500-HPA HEIGHT PATTERN PERSISTING
INTO THE WEEK-2 PERIOD. THE PATTERN IS OVERALL SIMILAR TO THE 6-10 DAY PERIOD
FORECASTS, WITH A DECREASE IN AMPLITUDE AND SLIGHT EASTWARD PROGRESSION OF THE
TROUGH OVER THE WESTERN CONUS. A RIDGE AND POSITIVE 500-HPA HEIGHT ANOMALIES
PERSIST OVER MUCH OF EASTERN NORTH AMERICA, EXCLUDING PARTS OF THE SOUTHEASTERN
CONUS.
BELOW NORMAL TEMPERATURES CONTINUE TO BE FAVORED FOR THE EASTERN ALEUTIANS AND
PARTS OF THE WEST COAST OF MAINLAND ALASKA, UNDER A PREDICTED TROUGH. ABOVE
NORMAL TEMPERATURES ARE FAVORED FOR NORTHEASTERN MAINLAND ALASKA, UNDER
ANOMALOUS SOUTHERLY FLOW. BELOW NORMAL TEMPERATURES CONTINUE TO BE FAVORED OVER
THE WESTERN CONUS AND EXTEND SLIGHTLY EASTWARD OVER THE ROCKIES IN WEEK-2,
WHILE ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE EASTERN TWO-THIRDS OF THE
CONUS, CONSISTENT WITH THE REFORECAST-CALIBRATED GEFS AND ECMWF TEMPERATURE
FORECASTS. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE HAWAIIAN
ISLANDS, EXCLUDING THE BIG ISLAND, CONSISTENT WITH THE TEMPERATURE
CONSOLIDATION.
ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR ALASKA IN WEEK-2, UNDER AND
AHEAD OF THE PREDICTED TROUGH. ABOVE NORMAL PRECIPITATION IS FAVORED FROM
CENTRAL CALIFORNIA AND THE PACIFIC NORTHWEST EASTWARD INTO THE NORTH-CENTRAL
CONUS, AHEAD OF THE PREDICTED TROUGH. BELOW NORMAL PRECIPITATION IS FAVORED FOR
PARTS OF THE SOUTHWEST, CONSISTENT WITH THE PRECIPITATION CONSOLIDATION AND
MOST PRECIPITATION TOOLS. BELOW NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR A
NARROW AREA OF THE WESTERN GULF COAST, CONSISTENT WITH THE PRECIPITATION
CONSOLIDATION. ABOVE NORMAL PRECIPITATION IS FAVORED FOR PARTS OF THE SOUTHEAST
CONSISTENT WITH MOST PRECIPITATION TOOLS AND POTENTIAL DEVELOPMENT OF A STORM
SYSTEM NEAR THE COAST. BELOW NORMAL PRECIPITATION CONTINUES TO BE SLIGHTLY
FAVORED FOR MUCH OF THE NORTHEASTERN CONUS, UNDER THE PREDICTED RIDGE. ABOVE
NORMAL PRECIPITATION IS SLIGHTLY FAVORED ACROSS HAWAII, CONSISTENT WITH THE
PRECIPITATION CONSOLIDATION.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 35% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 25% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: ABOUT-AVERAGE, 3 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG THE DYNAMICAL MODEL HEIGHT FORECASTS AND MOST TEMPERATURE
AND PRECIPITATION TOOLS, OFFSET BY DIFFERENCES IN TEMPERATURE AND PRECIPITATION
TOOLS FOR SOME AREAS AND A SLIGHTLY LESS AMPLIFIED MID-LEVEL HEIGHT PATTERN
FORECAST.
FORECASTER: D COLLINS
NOTES:
AUTOMATED FORECASTS ARE ISSUED ON SATURDAY AND SUNDAY. OCCASIONALLY MANUAL
INTERVENTION IS NECESSARY TO ADDRESS QUALITY CONTROL AND CONSISTENCY ISSUES. IN
THESE CASES, FORECASTS ARE MANUALLY DRAWN BUT A FULL DISCUSSION IS NOT ISSUED.
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 19.
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:
20050821 - 20060827 - 20050827 - 19970821 - 19820903
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:
20050824 - 19970820 - 20050831 - 20060826 - 19850825
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 16 - 20 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B A
SRN CALIF B A IDAHO B A NEVADA B A
W MONTANA B A E MONTANA A A WYOMING A A
UTAH B A ARIZONA B N COLORADO A A
NEW MEXICO A N N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A N S TEXAS A N W TEXAS A N
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A N WISCONSIN A N
ILLINOIS A N MISSISSIPPI A N MICHIGAN A B
INDIANA A B OHIO A N KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A B
VERMONT A B NEW HAMP A B MAINE A B
MASS A B CONN A B RHODE IS A B
PENN A N NEW JERSEY A A W VIRGINIA A A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA N A GEORGIA N A
FL PNHDL A A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN N A AK WESTERN N A AK INT BSN A A
AK S INT N A AK SO COAST N A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 18 - 24 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B A
SRN CALIF B N IDAHO B A NEVADA B A
W MONTANA B A E MONTANA A A WYOMING B A
UTAH B A ARIZONA B B COLORADO A N
NEW MEXICO A B N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A N S TEXAS A N W TEXAS A N
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A N LOUISIANA A N WISCONSIN A A
ILLINOIS A N MISSISSIPPI A N MICHIGAN A B
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA A N NEW YORK A B
VERMONT A B NEW HAMP A B MAINE A B
MASS A B CONN A B RHODE IS A B
PENN A N NEW JERSEY A N W VIRGINIA A N
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A A GEORGIA A N
FL PNHDL A N FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B N AK WESTERN N A AK INT BSN A A
AK S INT N A AK SO COAST N 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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