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FXUS06 KWBC 151910
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE OCTOBER 15 2024
6-10 DAY OUTLOOK FOR OCT 21 - 25 2024
THERE IS GOOD AGREEMENT BETWEEN THE 0Z ECMWF, GEFS AND CANADIAN ENSEMBLE MEAN
500-HPA HEIGHT FORECASTS ON THE PREDICTED CIRCULATION PATTERN ACROSS NORTH
AMERICA DURING THE 6-10 DAY PERIOD. DYNAMICAL MODELS PREDICT AN AMPLIFIED RIDGE
CENTERED OVER THE EASTERN ALEUTIAN ISLANDS AND WESTERN MAINLAND ALASKA. THE
ECMWF ENSEMBLE PREDICTS A POSITIVELY TILTED TROUGH OVER THE PACIFIC OCEAN NEAR
THE COAST OF THE PACIFIC NORTHWEST. THE GEFS AND CANADIAN ENSEMBLE MEMBERS
INDICATE GREATER UNCERTAINTY IN PREDICTING THE LOCATION OF A TROUGH OVER THE
NORTH PACIFIC TO THE WEST OF THE CONTIGUOUS U.S. (CONUS), SUCH THAT THE
PREDICTED NEGATIVE 500-HPA HEIGHT ANOMALY STRETCHES OUT ACROSS THE NORTH
PACIFIC. DYNAMICAL MODELS FAVOR A POSITIVE ARCTIC OSCILLATION THROUGH THE
PERIOD INTO WEEK 2 WITH POSITIVE 500-HPA HEIGHT ANOMALIES PREDICTED ACROSS MOST
OF THE CONUS, AND NEGATIVE 500-HPA HEIGHT ANOMALIES PREDICTED OVER THE ARCTIC.
ABOVE NORMAL TEMPERATURES ARE LIKELY FOR WESTERN AND NORTHERN MAINLAND ALASKA,
UNDER THE PREDICTED AMPLIFIED RIDGE. BELOW NORMAL TEMPERATURES ARE LIKELY FOR
FAR SOUTHEASTERN MAINLAND ALASKA AND SOUTHEAST ALASKA, UNDER ANOMALOUS
NORTHERLY MID-LEVEL FLOW. BELOW NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF
THE PACIFIC NORTHWEST, UNDER A PREDICTED MID-LEVEL TROUGH. ABOVE NORMAL
TEMPERATURES ARE LIKELY ACROSS MOST OF THE CONUS EXCLUDING PARTS OF THE
NORTHWESTERN CONUS, UNDER PREDICTED POSITIVE 500-HPA HEIGHT ANOMALIES. ABOVE
NORMAL TEMPERATURES ARE LIKELY FOR HAWAII, CONSISTENT WITH THE TEMPERATURE
CONSOLIDATION.
ABOVE NORMAL PRECIPITATION IS LIKELY FOR MOST OF MAINLAND ALASKA, EXCLUDING THE
SOUTH COAST, UNDER FAST ZONAL FLOW OVERTOP OF THE PREDICTED RIDGE. GREATER
PRECIPITATION AMOUNTS ARE PREDICTED AT THE START OF THE 6-10 DAY PERIOD LEADING
TO HIGH PROBABILITIES OF ABOVE NORMAL PRECIPITATION, EXCEEDING 60 PERCENT IN
SOME AREAS. BELOW NORMAL PRECIPITATION IS FAVORED FOR SOUTHEAST ALASKA, UNDER
ANOMALOUS NORTHERLY MID-LEVEL FLOW. ABOVE NORMAL PRECIPITATION IS SLIGHTLY
FAVORED FOR NORTHERN CALIFORNIA, PARTS OF OREGON, AND ACROSS THE NORTHERN TIER
OF THE CONUS FROM THE NORTHERN ROCKIES TO THE UPPER MISSISSIPPI VALLEY, AHEAD
OF THE PREDICTED TROUGH. ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR
PARTS OF THE CENTRAL PLAINS, CONSISTENT WITH THE PRECIPITATION CONSOLIDATION.
BELOW NORMAL PRECIPITATION IS FAVORED FOR MOST OF THE EASTERN CONUS, EXCLUDING
THE FLORIDA PENINSULA, UNDER PREDICTED POSITIVE 500-HPA HEIGHT ANOMALIES. ABOVE
NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR THE NORTHWESTERN HAWAIIAN ISLAND
OF KAUAI, CONSISTENT WITH THE PRECIPITATION CONSOLIDATION.
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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG THE DYNAMICAL MODEL HEIGHT FORECASTS, OFFSET BY
DE-AMPLIFYING ANOMALIES AND WEAKENING SIGNALS IN THE TEMPERATURE AND
PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR OCT 23 - 29 2024
DYNAMICAL MODEL FORECASTS FROM THE ECMWF, GEFS AND CANADIAN ENSEMBLE MEANS ARE
IN GOOD OVERALL AGREEMENT ON THE AVERAGE LARGE SCALE 500-HPA HEIGHT PATTERN IN
THE WEEK-2 PERIOD, DESPITE WEAKENING ANOMALIES AND INCREASING SPREAD IN THE
GEFS AND CANADIAN ENSEMBLE MODELS. DURING THE WEEK-2 PERIOD, DYNAMICAL MODELS
PREDICT A MUCH WEAKER POSITIVE 500-HPA HEIGHT ANOMALY OVER SOUTHWESTERN
MAINLAND ALASKA, WITH A FLATTENING OF THE RIDGE. MODELS PREDICT PERSISTENT
POSITIVE 500-HPA HEIGHT ANOMALIES ACROSS THE CONUS, AS THE LOCATION AND
AMPLITUDE OF A TROUGH OVER THE PACIFIC NORTHWEST BECOMES INCREASINGLY UNCERTAIN
IN THE GEFS AND ECMWF ENSEMBLE FORECASTS.
ABOVE NORMAL TEMPERATURES ARE LIKELY FOR MOST OF ALASKA, EXCLUDING SOUTHEASTERN
MAINLAND ALASKA AND SOUTHEAST ALASKA, UNDER A PREDICTED RIDGE AND POSITIVE
500-HPA HEIGHT ANOMALIES. BELOW NORMAL TEMPERATURES ARE LIKELY FOR SOUTHEAST
ALASKA, UNDER ANOMALOUS NORTHERLY MID-LEVEL FLOW. BELOW NORMAL TEMPERATURES ARE
FAVORED FOR PARTS OF THE PACIFIC NORTHWEST AND ACROSS THE FAR NORTHERN ROCKIES,
UNDER A PREDICTED TROUGH IN THE MANUAL BLEND OF MODEL 500-HPA HEIGHT FORECASTS.
ABOVE NORMAL TEMPERATURES ARE LIKELY FOR SOUTHERN CALIFORNIA, THE SOUTHWEST,
MOST OF THE GREAT PLAINS, AND THE EASTERN HALF OF THE CONUS, UNDER PERSISTENT
POSITIVE 500-HPA HEIGHT ANOMALIES. ABOVE NORMAL TEMPERATURES ARE LIKELY FOR
HAWAII IN WEEK 2, CONSISTENT WITH THE TEMPERATURE CONSOLIDATION.
ABOVE NORMAL PRECIPITATION IS FAVORED ACROSS MAINLAND ALASKA, UNDER ZONAL
MID-LEVEL FLOW. BELOW NORMAL PRECIPITATION IS FAVORED FOR SOUTHERN AREAS OF
SOUTHEAST ALASKA, UNDER ANOMALOUS NORTHERLY FLOW. ABOVE NORMAL PRECIPITATION IS
FAVORED FOR MUCH OF THE WESTERN CONUS INTO THE NORTHERN PLAINS, AHEAD OF A
PREDICTED TROUGH. ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR PARTS OF
THE CENTRAL PLAINS AND WESTERN GREAT LAKES REGION, CONSISTENT WITH THE
PRECIPITATION CONSOLIDATION. BELOW NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR
THE MID-ATLANTIC AND NORTHEAST ATLANTIC COASTS, UNDER A PREDICTED RIDGE AND
CONSISTENT WITH THE PRECIPITATION CONSOLIDATION. ABOVE NORMAL PRECIPITATION IS
SLIGHTLY FAVORED FOR NORTHWESTERN ISLANDS OF HAWAII, CONSISTENT WITH THE
PRECIPITATION CONSOLIDATION.
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: ABOUT AVERAGE, 3 OUT OF 5, DUE TO
GOOD OVERALL AGREEMENT AMONG THE DYNAMICAL MODEL HEIGHT FORECASTS, OFFSET BY
VARIABILITY OF THE PREDICTED FORECAST PATTERN AND WEAKENING HEIGHT ANOMALIES
DURING THE PERIOD.
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
OCTOBER 17.
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:
20081001 - 19991024 - 20031017 - 19901026 - 19531009
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:
20080930 - 20031018 - 19991024 - 20051023 - 19801007
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 21 - 25 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B N OREGON N N NRN CALIF A A
SRN CALIF A N IDAHO N A NEVADA A N
W MONTANA N A E MONTANA A A WYOMING A N
UTAH A N ARIZONA A N COLORADO A N
NEW MEXICO A N N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A N
N TEXAS A N S TEXAS A N W TEXAS A N
MINNESOTA A A IOWA A A MISSOURI A N
ARKANSAS A B LOUISIANA A B WISCONSIN A N
ILLINOIS A N MISSISSIPPI A B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A B 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 B NEW JERSEY A B W VIRGINIA A B
MARYLAND A B DELAWARE A B VIRGINIA A B
N CAROLINA A B S CAROLINA A B GEORGIA A B
FL PNHDL A B FL PENIN A N AK N SLOPE A A
AK ALEUTIAN N N AK WESTERN A A AK INT BSN A A
AK S INT N A AK SO COAST N N AK PNHDL B B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 23 - 29 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B N OREGON B A NRN CALIF N A
SRN CALIF A N IDAHO N A NEVADA N A
W MONTANA N A E MONTANA N A WYOMING A A
UTAH A A ARIZONA A B COLORADO A N
NEW MEXICO A B N DAKOTA N A S DAKOTA A A
NEBRASKA A N KANSAS A N 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 A MISSISSIPPI A N MICHIGAN A A
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA A N NEW YORK A N
VERMONT A N NEW HAMP A B MAINE A B
MASS A B CONN A B RHODE IS A B
PENN A B NEW JERSEY A B W VIRGINIA A N
MARYLAND A B DELAWARE A B VIRGINIA A B
N CAROLINA A B S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE A A
AK ALEUTIAN N A AK WESTERN A A AK INT BSN A A
AK S INT N A AK SO COAST N A AK PNHDL B N
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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