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FXUS06 KWBC 121922
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 12 2024
6-10 DAY OUTLOOK FOR SEP 18 - 22 2024
THERE IS GOOD AGREEMENT BETWEEN THE 0Z ECMWF, GEFS AND CANADIAN ENSEMBLE MEAN
500-HPA HEIGHT FORECASTS ON AN AMPLIFIED CIRCULATION PATTERN ACROSS NORTH
AMERICA. DYNAMICAL MODELS PREDICT A TROUGH OVER THE BERING SEA AND MAINLAND
ALASKA. A TROUGH IS PREDICTED OVER WESTERN CANADA AND THE WESTERN CONTIGUOUS
U.S. (CONUS), WITH SOME AMPLIFICATION AND EASTWARD PROGRESSION RELATIVE TO
YESTERDAY’S 6-10 DAY FORECASTS. AN AMPLIFIED RIDGE IS PREDICTED OVER EASTERN
CANADA AND THE NORTHEASTERN CONUS. NEGATIVE 500-HPA HEIGHT ANOMALIES AND A
TROUGH ARE PREDICTED OVER THE SOUTHEASTERN CONUS. DYNAMICAL MODELS PREDICT
WEAKENING ANOMALIES ASSOCIATED WITH THE TROUGH OVER THE WESTERN CONUS TOWARDS
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 FAVORED
FOR NORTHEASTERN 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, WITH SOME REDUCTION IN PROBABILITIES DUE A
CHANGING PATTERN DURING THE PERIOD. 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 FOR ABOVE NORMAL
TEMPERATURES EXCEED 90 PERCENT FOR MUCH OF THE WESTERN GREAT LAKES REGION,
UNDER LARGE POSITIVE 500-HPA HEIGHT ANOMALIES. NEAR NORMAL IS FAVORED FOR A
SMALL AREA OF THE SOUTHEAST WHERE DYNAMICAL MODEL TEMPERATURE TOOLS DISAGREE.
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE HAWAIIAN ISLANDS, CONSISTENT WITH
THE TEMPERATURE CONSOLIDATION.
ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR MOST OF ALASKA, EXCLUDING
PARTS OF NORTHWESTERN MAINLAND ALASKA, UNDER AND AHEAD OF A PREDICTED TROUGH
AND CONSISTENT WITH DYNAMICAL MODEL PRECIPITATION FORECASTS. ABOVE NORMAL
PRECIPITATION IS FAVORED ACROSS MUCH OF THE WESTERN AND CENTRAL CONUS,
EXCLUDING PARTS OF THE SOUTHWEST AND TEXAS, AHEAD OF THE PREDICTED TROUGH.
BELOW NORMAL PRECIPITATION IS FAVORED FOR PARTS OF THE SOUTHWEST AND THE
WESTERN GULF COAST REGION, WHERE PRECIPITATION TOOLS ARE CONSISTENT. ABOVE
NORMAL PRECIPITATION IS LIKELY FOR PARTS OF THE SOUTHEAST AND MID-ATLANTIC
COASTS, WITH PREDICTED DEVELOPMENT OF A STORM SYSTEM OFF THE COAST. 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 THE PRECIPITATION CONSOLIDATION.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 40% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 40% 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 AND AN AMPLIFIED
PATTERN, OFFSET BY DIFFERENCES IN TEMPERATURE AND PRECIPITATION TOOLS FOR SOME
AREAS AND A CHANGING PATTERN LATER IN THE PERIOD.
8-14 DAY OUTLOOK FOR SEP 20 - 26 2024
DYNAMICAL MODEL FORECASTS FROM THE ECMWF, GEFS AND CANADIAN ENSEMBLE MEANS ARE
IN GOOD AGREEMENT ON THE AVERAGE LARGE SCALE 500-HPA HEIGHT PATTERN IN THE
WEEK-2 PERIOD. THE PATTERN IS OVERALL SIMILAR TO THE 6-10 DAY PERIOD FORECASTS,
WITH INCREASING NEGATIVE 500-HPA HEIGHT ANOMALIES OVER THE GULF OF ALASKA AND A
DECREASE IN AMPLITUDE OF THE TROUGH OVER THE WESTERN CONUS WITH RISING HEIGHTS
LATER IN THE PERIOD. A RIDGE AND POSITIVE 500-HPA HEIGHT ANOMALIES PERSIST OVER
MUCH OF EASTERN NORTH AMERICA, EXCLUDING PARTS OF THE SOUTHEASTERN CONUS.
BELOW NORMAL TEMPERATURES ARE FAVORED FOR THE EASTERN ALEUTIANS AND THE WEST
COAST OF MAINLAND ALASKA, UNDER A PREDICTED TROUGH. ABOVE NORMAL TEMPERATURES
ARE FAVORED FOR PARTS OF NORTHEASTERN MAINLAND ALASKA, UNDER ANOMALOUS
SOUTHERLY FLOW. NEAR-TO-BELOW NORMAL TEMPERATURES CONTINUE TO BE FAVORED OVER
MUCH OF THE WESTERN CONUS, ALTHOUGH PROBABILITIES FOR BELOW NORMAL TEMPERATURES
HAVE DECREASED SUBSTANTIALLY IN WEEK-2, AS HEIGHTS ARE PREDICTED TO RISE DURING
THE PERIOD. 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 THE HAWAIIAN ISLANDS,
CONSISTENT WITH THE TEMPERATURE CONSOLIDATION.
ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR SOUTHERN AND EASTERN
MAINLAND ALASKA IN WEEK-2, UNDER AND AHEAD OF THE PREDICTED TROUGH, WITH
ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FOR SOUTHEAST ALASKA,
AHEAD OF AN AMPLIFYING TROUGH. ABOVE NORMAL PRECIPITATION IS FAVORED FROM THE
PACIFIC NORTHWEST EASTWARD INTO THE NORTHERN AND CENTRAL PLAINS AND THE CENTRAL
AND UPPER MISSISSIPPI VALLEY, AHEAD OF THE PREDICTED TROUGH. BELOW NORMAL
PRECIPITATION IS FAVORED FOR MUCH OF THE SOUTHWEST, CONSISTENT WITH THE
PRECIPITATION CONSOLIDATION AND MOST PRECIPITATION TOOLS. BELOW NORMAL
PRECIPITATION IS SLIGHTLY FAVORED FOR A SMALL AREA OF THE WESTERN GULF COAST,
CONSISTENT WITH THE PRECIPITATION CONSOLIDATION. ABOVE NORMAL PRECIPITATION IS
FAVORED FOR PARTS OF THE SOUTHEAST AND MID-ATLANTIC, CONSISTENT WITH MOST
PRECIPITATION TOOLS AND POTENTIAL DEVELOPMENT OF A STORM SYSTEM NEAR THE COAST.
BELOW NORMAL PRECIPITATION CONTINUES TO BE SLIGHTLY FAVORED FOR PARTS OF THE
NORTHEAST, 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: 40% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 40% 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 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 AN EVOLVING 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:
20060828 - 20050903 - 20050828 - 19940911 - 20050823
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:
20050902 - 20050826 - 20060827 - 19940911 - 19530825
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 18 - 22 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 B A
UTAH B A ARIZONA B B COLORADO A A
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 B W TEXAS A A
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 B OHIO A B 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 B NEW JERSEY A N W VIRGINIA A N
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA N A GEORGIA N A
FL PNHDL N A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN N A AK WESTERN N N AK INT BSN N A
AK S INT N A AK SO COAST N A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 20 - 26 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON N A NRN CALIF N N
SRN CALIF B N IDAHO B A NEVADA B N
W MONTANA N A E MONTANA A A WYOMING B A
UTAH B B ARIZONA B B COLORADO A A
NEW MEXICO A B 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 A
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A N WISCONSIN A A
ILLINOIS A N MISSISSIPPI A N MICHIGAN A B
INDIANA A N OHIO A B KENTUCKY A N
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 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 A
AK ALEUTIAN B N AK WESTERN N N AK INT BSN N 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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