855
FXUS06 KWBC 261902
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 26 2024
6-10 DAY OUTLOOK FOR OCT 02 - 06 2024
THE 6-10 DAY MEAN MID-LEVEL HEIGHT PATTERN FROM THE GEFS, ECENS, AND CANADIAN
ENSEMBLE FORECAST POSITIVE MID-LEVEL HEIGHT ANOMALIES AND MID-LEVEL RIDGING
OVER THE WESTERN AND CENTRAL CONTIGUOUS U.S. (CONUS). NEAR-NORMAL HEIGHTS
REMAIN FORECAST ACROSS THE EASTERN CONUS WITH A SHORTWAVE TROUGH PROGRESSING
THROUGH THE REGION BEFORE MOVING OFF THE EAST COAST BY THE END OF THE PERIOD.
IN ALASKA, A MID-LEVEL TROUGH IS FORECAST ACROSS MUCH OF THE STATE WITH THE
STRONGEST NEGATIVE ANOMALIES FOCUSED ACROSS THE GULF OF ALASKA APPROACHING THE
PACIFIC NORTHWEST. NEGATIVE 500-HPA HEIGHT ANOMALIES REMAIN ROBUST WITH A
FAIRLY STATIONARY MID-LEVEL HEIGHT PATTERN DEVELOPING. IN HAWAII, NEAR-NORMAL
500-HPA HEIGHT ANOMALIES ARE FORECAST.
ABOVE-NORMAL TEMPERATURES ARE FAVORED ACROSS MUCH OF THE CONUS DURING THE 6-10
DAY PERIOD. THE EXCEPTION IS ACROSS PORTIONS OF THE OHIO AND TENNESSEE RIVER
VALLEYS, EAST THROUGH THE MID-ATLANTIC AND CAROLINAS WHERE NEAR-NORMAL
TEMPERATURES ARE FAVORED. THE NEAR-NORMAL TEMPERATURE CHANCES ARE ASSOCIATED
WITH A WEAK MID-LEVEL TROUGH OVER THE EASTERN CONUS. WHILE THE ECENS REFORECAST
MAINTAINS WARMER THAN NORMAL CHANCES ACROSS THE REGION MANY OTHER TOOLS ARE
NEAR- TO EVEN BELOW-NORMAL. OTHERWISE, THE STRONG POSITIVE HEIGHT ANOMALIES
FAVORED IN THE WEST STRETCHING INTO THE CENTRAL CONUS BRING STRONG CHANCES FOR
ABOVE-NORMAL TEMPERATURES INTO THE INTERIOR WEST, PLAINS, AND UPPER-MISSISSIPPI
VALLEY. A TROUGH APPROACHING THE PACIFIC NORTHWEST REDUCES PROBABILITIES FOR
ABOVE-NORMAL TEMPERATURES WITH ONSHORE FLOW FAVORED INTO THE REGION. IN ALASKA,
NEAR- TO BELOW-NORMAL TEMPERATURES ARE FAVORED FOR SOUTHERN ALASKA WITH
TROUGHING FAVORED ACROSS MUCH OF THE STATE. AN AREA OF ABOVE-NORMAL
TEMPERATURES IS FAVORED IN THE NORTHERN MAINLAND DISPLACED FROM THE MID-LEVEL
TROUGH. NEAR TO ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR HAWAII CONSISTENT
WITH THE AUTOBLEND AND CONSOLIDATION TOOLS.
THE 6-10 DAY PRECIPITATION FORECAST FAVORS ABOVE-NORMAL PRECIPITATION FOR
PORTIONS OF FLORIDA AND THE GULF COAST ASSOCIATED WITH A FRONTAL BOUNDARY
DRAPED ACROSS THE SOUTHEAST. ADDITIONAL MOISTURE FROM THE TROPICS MAY INCREASE
PRECIPITATION ACROSS THE REGION. ABOVE-NORMAL PRECIPITATION IS ALSO FAVORED
ACROSS PORTIONS OF THE NORTHEAST ASSOCIATED WITH A SURFACE LOW-PRESSURE SYSTEM
EXITING THE REGION. STRONG HIGH PRESSURE IS FORECAST TO BUILD IN BEHIND THE
EXITING SYSTEM ACROSS THE EASTERN CONUS BRINGING BELOW-NORMAL PRECIPITATION
CHANCES TO MUCH OF THE EASTERN CONUS. BENEATH THE FORECAST MID-LEVEL RIDGE
ACROSS THE CENTRAL AND WESTERN CONUS BELOW-NORMAL PRECIPITATION CHANCES REMAIN
STRONGLY FAVORED. ANOTHER SMALL, SLIGHT TILT TOWARDS ABOVE-NORMAL PRECIPITATION
IS FORECAST FOR THE PACIFIC NORTHWEST WHERE A TROUGH ACROSS THE GULF OF ALASKA
MAY BRING ENHANCED PRECIPITATION TO THE REGION. IN ALASKA, ABOVE-NORMAL
PRECIPITATION IS FAVORED ACROSS THE SOUTHERN HALF OF THE STATE ASSOCIATED WITH
ONE OR MORE EXTRA-TROPICAL CYCLONES THAT ARE FORECAST TO MOVE THROUGH THE
REGION WITHIN THE BROADER MID-LEVEL TROUGH. IN HAWAII, NEAR-NORMAL
PRECIPITATION IS FAVORED CONSISTENT WITH THE AVAILABLE TOOLS.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 35% OF TODAY'S 6Z 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. GOOD
AGREEMENT AMONG THE DYNAMICAL TOOLS IS OFFSET BY UNCERTAINTY REGARDING THE
EVOLUTION OF THE HEIGHT PATTERN IN THE SOUTHEAST.
8-14 DAY OUTLOOK FOR OCT 04 - 10 2024
THE WEEK-2 HEIGHT FORECAST IS SIMILAR TO THE 6-10 DAY PERIOD, WITH CONTINUED
GOOD AGREEMENT AMONG THE MODELS FOR ABOVE-NORMAL 500-HPA HEIGHTS ACROSS THE
WESTERN AND CENTRAL CONUS. MEANWHILE, NEAR-NORMAL HEIGHTS REMAIN FORECAST IN
THE EASTERN CONUS WITH SOME UNCERTAINTY REGARDING THE POTENTIAL FOR ANOTHER
TROPICAL WAVE TO MOVE INTO THE REGION. ENSEMBLES FROM THE GEFS AND ECENS SHOW
THE POTENTIAL OF ANOTHER TROPICAL DISTURBANCE DEVELOPING IN THE CARIBBEAN OR
GULF OF MEXICO DURING THE WEEK-2 PERIOD. THIS AREA SHOULD BE WATCHED CAREFULLY
FOR POTENTIAL DEVELOPMENT OF A TROPICAL SYSTEM IN LIGHT OF HURRICANE HELENE IN
THIS AREA DURING WEEK-1. IN ALASKA, TROUGHING REMAINS FORECAST WITH
BELOW-NORMAL 500-HPA HEIGHTS. THE STRONGEST NEGATIVE ANOMALIES ARE FOUND IN THE
GULF OF ALASKA. IN HAWAII, NEAR-NORMAL 500-HPA HEIGHTS ARE FORECAST.
DURING WEEK-2, ABOVE-NORMAL TEMPERATURES REMAIN FAVORED ACROSS MUCH OF THE
CONUS, EXCLUDING PORTIONS OF THE MID-ATLANTIC AND PACIFIC NORTHWEST. IN THE
MID-ATLANTIC A TROUGH IS FORECAST TO PROGRESS EAST OF THE EAST COAST DURING
WEEK-2 AND WARMING TEMPERATURES ARE FAVORED BEHIND THIS SYSTEM. HOWEVER, THERE
IS A LOT OF UNCERTAINTY IN THE PATTERN ACROSS THIS REGION AND SO MUCH OF THE
SOUTHEAST IS ONLY SLIGHTLY FAVORED TO SEE ABOVE-NORMAL TEMPERATURES. IN THE
PACIFIC NORTHWEST, A TROUGH ALONG THE WEST COAST IS LIKELY TO BRING SLIGHTLY
ENHANCED ONSHORE FLOW INTO THE AREA AND NEAR-NORMAL TEMPERATURES ARE FAVORED.
ELSEWHERE IN THE CONUS, CONTINUED MID-LEVEL RIDGING AND POSITIVE MID-LEVEL
HEIGHT ANOMALIES BRING STRONG CHANCES FOR ABOVE-NORMAL TEMPERATURES TO MUCH OF
THE INTERIOR WEST, PLAINS, AND MISSISSIPPI VALLEY. IN ALASKA, ABOVE-NORMAL
TEMPERATURES REMAIN FORECAST IN THE NORTHERN AND EASTERN MAINLAND WITH NEAR TO
BELOW-NORMAL TEMPERATURES FAVORED ALONG THE WESTERN COASTAL REGIONS AND
SOUTHEAST ALASKA. IN HAWAII, NEAR-NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF
THE STATE, HOWEVER, ABOVE-NORMAL TEMPERATURES ARE SLIGHTLY FAVORED ACROSS SOME
OF THE WESTERN ISLANDS.
DURING THE WEEK-2 PERIOD, BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS MUCH OF
THE CONUS BENEATH A STRONG MID-LEVEL RIDGE AND SURFACE HIGH PRESSURE.
EXCEPTIONS ARE ACROSS PARTS OF THE SOUTHEAST AND PACIFIC NORTHWEST WHERE
ABOVE-NORMAL PRECIPITATION IS FAVORED. IN THE SOUTHEAST, A FRONTAL SYSTEM IS
FORECAST TO BE PROGRESSING THROUGH THE REGION EARLY IN THE PERIOD. MANY
ENSEMBLE MEMBERS FROM THE GEFS AND ECENS DEPICT CHANCES FOR A TROPICAL SYSTEM
TO DEVELOP IN THE WESTERN CARIBBEAN OR GULF OF MEXICO FOLLOWING HURRICANE
HELENE. THERE IS A LOT OF UNCERTAINTY BUT ADDITIONAL TROPICAL MOISTURE IS
FAVORED AND ABOVE-NORMAL PRECIPITATION IS FORECAST FOR MUCH OF THE GULF COAST.
IN THE PACIFIC NORTHWEST, A SLIGHT TILT TOWARDS ABOVE-NORMAL PRECIPITATION IS
FORECAST WITH A MID-LEVEL TROUGH ALONG THE BRITISH COLUMBIA COAST. THIS TROUGH
IS ALSO FORECAST TO BRING ABOVE-NORMAL PRECIPITATION TO MUCH OF SOUTHERN
ALASKA. IN HAWAII, NEAR-NORMAL PRECIPITATION IS FORECAST CONSISTENT WITH THE
MAJORITY OF AVAILABLE TOOLS.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 25% OF TODAY'S 6Z 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: AVERAGE, 3 OUT OF 5, FAIR
AGREEMENT AMONG THE TOOLS OFFSET BY A LESS AMPLIFIED AND PROGRESSIVE HEIGHT
PATTERN.
FORECASTER: RYAN BOLT
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:
19870913 - 19551006 - 19870918 - 20071010 - 20081006
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:
19870916 - 19870911 - 19551009 - 20071009 - 20010926
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 02 - 06 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N N OREGON A B NRN CALIF A B
SRN CALIF A N IDAHO A B NEVADA A B
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A N W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA A N WISCONSIN A B
ILLINOIS A B MISSISSIPPI A N MICHIGAN A B
INDIANA N B OHIO N B KENTUCKY N B
TENNESSEE N B ALABAMA A N NEW YORK A N
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A N RHODE IS A A
PENN N B NEW JERSEY N N W VIRGINIA N B
MARYLAND N B DELAWARE N N VIRGINIA N B
N CAROLINA N N S CAROLINA N N GEORGIA A N
FL PNHDL A A FL PENIN A A AK N SLOPE A N
AK ALEUTIAN B A AK WESTERN N A AK INT BSN A N
AK S INT N A AK SO COAST N A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 04 - 10 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A N NRN CALIF A B
SRN CALIF A N IDAHO A B NEVADA A B
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A N W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA A N WISCONSIN A B
ILLINOIS A B MISSISSIPPI A N MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A N NEW YORK A B
VERMONT A N NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS A N
PENN A B NEW JERSEY N B W VIRGINIA A B
MARYLAND N B DELAWARE N B VIRGINIA N B
N CAROLINA N B S CAROLINA N N GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A N
AK ALEUTIAN B N AK WESTERN N N 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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