135
FXUS06 KWBC 211939
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED AUGUST 21 2024
6-10 DAY OUTLOOK FOR AUG 27 - 31 2024
THE GEFS, ECENS, AND CMCE ENSEMBLE MEANS ARE IN GOOD AGREEMENT ON THE MEAN
500-HPA CIRCULATION PATTERN OVER THE FORECAST DOMAIN DURING THE 6-10 DAY
FORECAST PERIOD. IN THE FULL 500-HPA HEIGHT FIELD, WEAK MID-LEVEL TROUGHS ARE
PREDICTED NEAR THE WEST AND EAST COASTS OF THE CONTIGUOUS U.S. (CONUS), AND A
FLAT TO LOW-AMPLITUDE RIDGE IS DEPICTED ACROSS THE EAST-CENTRAL STATES. IN THE
HEIGHT ANOMALY FIELDS, SMALL POSITIVE HEIGHT DEPARTURES ARE FAVORED ACROSS MOST
OF THE CONUS, WITH THE GREATER ANOMALIES CENTERED OVER SOUTHEASTERN CANADA AND
OFF THE BRITISH COLUMBIA COAST (BOTH ANOMALIES EXCEEDING +120 M). A WEAKENING
MID-LEVEL TROUGH IS PREDICTED TO BE CENTERED OVER THE EASTERN BERING SEA AND
WESTERN ALASKA, ACCOMPANIED BY NEGATIVE 500-HPA HEIGHT ANOMALIES ACROSS
APPROXIMATELY THE WESTERN HALF OF THE STATE. MOSTLY NEAR NORMAL HEIGHTS ARE
PREDICTED ACROSS THE EASTERN HALF OF MAINLAND ALASKA. RISING 500-HPA HEIGHTS
ARE FAVORED OVER THE PANHANDLE, ASSOCIATED WITH AN AMPLIFYING RIDGE CENTERED
OFF THE BRITISH COLUMBIA COAST. OVER THE HAWAIIAN ARCHIPELAGO, MID-LEVEL
HEIGHTS ARE PREDICTED TO BE NEAR OR SLIGHTLY ABOVE NORMAL.
THE 6-10 DAY TEMPERATURE OUTLOOK FAVORS BELOW NORMAL TEMPERATURES OVER
WASHINGTON STATE, EASTERN OREGON, IDAHO, FAR NORTHERN UTAH, MONTANA, AND MOST
OF WYOMING, AS DEPICTED BY THE AUTO-TEMPERATURE FORECAST. THIS FORECAST
REPRESENTS A REASONABLE COMPROMISE BETWEEN THE VARIOUS MODELS WHICH DIFFER ON
THE SPATIAL EXTENT OF THE FAVORED COOLER-THAN-NORMAL TEMPERATURES. THE RAW AND
BIAS-CORRECTED TEMPERATURE TOOLS DEPICT A SOMEWHAT BROADER COVERAGE OF FAVORED
BELOW NORMAL TEMPERATURES COMPARED TO THE RE-FORECAST TEMPERATURE TOOLS. FOR
MOST OF THE REMAINDER OF THE CONUS, ABOVE NORMAL TEMPERATURES ARE FAVORED,
SUPPORTED BY NEARLY ALL TEMPERATURE TOOLS AND CONSISTENT WITH A BROAD MID-LEVEL
RIDGE AND ASSOCIATED POSITIVE HEIGHT ANOMALIES. MAXIMUM PROBABILITIES FAVORING
ABOVE NORMAL TEMPERATURES EXCEED 70% OVER THE LOWER OHIO VALLEY. FOR ALASKA,
NEARLY ALL TOOLS AGREE ON FAVORED BELOW NORMAL TEMPERATURES FOR MOST OF THE
MAINLAND, THE ALASKA PENINSULA, AND THE ALEUTIANS, CONSISTENT WITH THE BROAD
MID-LEVEL TROUGH AND ASSOCIATED NEGATIVE HEIGHT ANOMALIES OVER THAT REGION.
NEAR NORMAL TEMPERATURES ARE MOSTLY FAVORED ACROSS THE PANHANDLE AND
NORTHEASTERN ALASKA MAINLAND. MAXIMUM PROBABILITIES FAVORING BELOW NORMAL
TEMPERATURES EXCEED 60% OVER PORTIONS OF WESTERN ALASKA. ABOVE NORMAL
TEMPERATURES ARE INDICATED OVER THE HAWAIIAN ISLANDS, BASED ON THE ERF-CON AND
AUTOMATED TEMPERATURE TOOLS.
THE 6-10 DAY PRECIPITATION OUTLOOK FAVORS ABOVE NORMAL PRECIPITATION ALONG THE
NORTHERN TIER OF STATES FROM THE NORTHERN INTERMOUNTAIN REGION EASTWARD TO THE
UPPER GREAT LAKES. THIS AREA OF FAVORED ABOVE NORMAL PRECIPITATION ALSO EXTENDS
SOUTHWESTWARD FROM THE UPPER GREAT LAKES REGION ACROSS NEBRASKA AND THE FOUR
CORNERS STATES OF THE AMERICAN SOUTHWEST. THIS IS RELATED TO THE EXPECTED
PASSAGE OF A LOW PRESSURE SYSTEM PRIMARILY OVER THE CANADIAN PRAIRIES LATER IN
THE FORECAST PERIOD. THE FOUR CORNERS REGION PRECIPITATION IS MOST LIKELY
RELATED TO THE SUMMER MONSOON. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED OVER
THE FLORIDA PENINSULA, AND SOUTHERN AND SOUTHWESTERN TEXAS. THESE AREAS
GENERALLY COINCIDE WITH THE SOUTHERN FLANK OF THE AZORES-BERMUDA HIGH. BELOW
NORMAL PRECIPITATION IS FAVORED FROM THE SOUTH-CENTRAL GREAT PLAINS REGION
EAST-NORTHEASTWARD ACROSS THE MIDDLE MISSISSIPPI VALLEY, OHIO AND TENNESSEE
VALLEYS, AND INTERIOR GULF COAST REGION, COINCIDENT WITH THE BROAD MID-LEVEL
RIDGE AND POSITIVE HEIGHT DEPARTURES PREDICTED OVER THAT REGION. BELOW NORMAL
PRECIPITATION IS ALSO FAVORED FOR NORTHERN AND CENTRAL SECTIONS OF THE PACIFIC
COAST STATES, WHICH HAS THE SUPPORT OF MANY OF THE PRECIPITATION TOOLS.
ELSEWHERE, WHICH INCLUDES A LARGE PORTION OF THE CONUS, NEAR NORMAL
PRECIPITATION IS FAVORED. IN ALASKA, THERE IS EXCELLENT AGREEMENT AMONG THE
PRECIPITATION TOOLS FOR ABOVE NORMAL PRECIPITATION ACROSS MOST OF THE STATE,
ASSOCIATED WITH WIDESPREAD ONSHORE FLOW AT LOW-LEVELS AND MID-LEVELS
ACCOMPANYING AND AHEAD OF THE TROUGH PREDICTED OVER THE EASTERN BERING SEA AND
WESTERN ALASKA. FOR HAWAII, THE ERF-CON AND AUTOMATED PRECIPITATION TOOLS
FAVOR ABOVE NORMAL PRECIPITATION DURING THE 6-10 DAY PERIOD, ASSOCIATED WITH
THE POTENTIAL FOR TWO TROPICAL SYSTEMS TO MOVE THROUGH THE AREA. PROBABILITIES
FAVORING ABOVE NORMAL RAINFALL EXCEED 50% OVER THE HAWAIIAN ISLANDS.
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, ON A SCALE OF
1-5, DUE TO GOOD AGREEMENT AMONG THE VARIOUS HEIGHT FORECASTS AND SURFACE
TEMPERATURE FIELDS, OFFSET SOMEWHAT BY GREATER DIFFERENCES AMONG THE
PRECIPITATION GUIDANCE.
8-14 DAY OUTLOOK FOR AUG 29 - SEP 04, 2024
DURING WEEK-2, THE ENSEMBLE MEANS ARE IN REASONABLE AGREEMENT ON THE MEAN
CIRCULATION PATTERN ACROSS THE FORECAST DOMAIN. IN THE FULL HEIGHT FIELDS, A
WEAK TROUGH IS DEPICTED NEAR THE WEST COAST AND A BROAD RIDGE IS INDICATED OVER
THE WEST-CENTRAL CONUS. A LOW-AMPLITUDE TROUGH IS PREDICTED OVER THE EAST. IN
THE HEIGHT ANOMALY FIELDS, MOST OF THE CONUS IS EXPECTED TO BE UNDER WEAKLY
ABOVE NORMAL 500-HPA HEIGHTS, WITH THE TWO LARGER POSITIVE HEIGHT ANOMALY
CENTERS (>60 M) LOCATED OVER ATLANTIC CANADA AND NEAR VANCOUVER. IN ALASKA, A
WEAKENING TROUGH IS PREDICTED OVER THE EASTERN BERING SEA AND WESTERN ALASKA
WITH PREDICTED HEIGHT DEPARTURES NEAR ZERO. THE MANUAL HEIGHT BLEND DEPICTS
POSITIVE HEIGHT ANOMALIES AND ASSOCIATED MID-LEVEL RIDGING ACROSS THE EASTERN
HALF OF ALASKA. WELL TO THE SOUTH, HEIGHTS ARE FORECAST TO BE NEAR OR SLIGHTLY
ABOVE NORMAL IN THE VICINITY OF THE HAWAIIAN ISLANDS.
THE 8-14 DAY TEMPERATURE OUTLOOK FAVORS ABOVE NORMAL TEMPERATURES OVER MUCH OF
THE LOWER 48 STATES, SUPPORTED BY MUCH OF THE REFORECAST AND RAW TEMPERATURE
GUIDANCE. MAXIMUM PROBABILITIES FAVORING ABOVE NORMAL TEMPERATURES EXCEED 50%
OVER THE PACIFIC NORTHWEST, NORTHERN NEW ENGLAND, AND MUCH OF THE SOUTHEASTERN
QUARTER OF THE CONUS. IN SOUTH FLORIDA, PROBABILITIES EXCEED 60% FOR ABOVE
NORMAL TEMPERATURE CHANCES. A LARGE AREA OF FAVORED NEAR TO BELOW NORMAL
TEMPERATURES IS INDICATED FROM THE NORTHERN HIGH PLAINS EASTWARD TO THE UPPER
MISSISSIPPI VALLEY, BASED ON THE PREDICTED PASSAGE OF A MID-LEVEL TROUGH AND
ACCOMPANYING COLD FRONT. IN ALASKA, COVERAGE OF FAVORED BELOW NORMAL
TEMPERATURES IS EXPECTED TO DECREASE DURING WEEK-2 TO INCLUDE ONLY THE FAR
WESTERN PARTS OF THE STATE. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MOST OF
THE REMAINDER OF THE MAINLAND, WITH NEAR NORMAL TEMPERATURES ACROSS MOST OF
SOUTHEAST ALASKA, BASED ON A SUBJECTIVE CONSENSUS OF AVAILABLE TEMPERATURE
GUIDANCE. THE ERF-CON AND AUTOMATED TEMPERATURE TOOLS SUPPORT ABOVE NORMAL
TEMPERATURES ACROSS HAWAII, SIMILAR TO THE EARLIER 6-10 DAY TEMPERATURE OUTLOOK.
THE 8-14 DAY PRECIPITATION OUTLOOK CONTINUES TO BE CHARACTERIZED BY SIGNIFICANT
UNCERTAINTY, AS INDICATED BY THE BROAD EXPANSE OF FAVORED NEAR NORMAL
PRECIPITATION ACROSS THE LOWER 48 STATES, AND THE RELATIVELY WEAK TILTS TOWARD
ABOVE OR BELOW NORMAL PRECIPITATION. THE REASONING BEHIND THE FAVORED AREAS OF
ABOVE NORMAL PRECIPITATION WAS DESCRIBED EARLIER IN THE 6-10 DAY DISCUSSION,
EXCEPT FOR THE EASTERN SEABOARD WHERE A FRONTAL SYSTEM TILTS THE ODDS TOWARDS
ABOVE NORMAL PRECIPITATION. ODDS FAVOR BELOW NORMAL PRECIPITATION FROM THE
SOUTH-CENTRAL PLAINS TO THE OHIO AND TENNESSEE VALLEYS, AND INTERIOR PORTIONS
OF THE GULF COAST STATES, SIMILAR TO THE PRECIPITATION OUTLOOK FOR THE 6-10 DAY
PERIOD. OVER THE PACIFIC NORTHWEST, BELOW NORMAL PRECIPITATION IS FAVORED IN
PROXIMITY TO A MODERATELY STRONG ANOMALOUS RIDGE. MOST TOOLS CONTINUE TO FAVOR
ANOMALOUS WETNESS FOR MOST OF ALASKA AND HAWAII.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 30% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 30% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: NEAR AVERAGE, 3, ON A SCALE OF
1-5, DUE TO REASONABLE AGREEMENT AMONG THE VARIOUS HEIGHT FORECASTS AND SURFACE
TEMPERATURE FORECASTS, BUT SUBSTANTIALLY OFFSET BY POOR AGREEMENT AMONG THE
PRECIPITATION TOOLS.
FORECASTER: ANTHONY A
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:
19830830 - 19540828 - 19820814 - 19530824 - 19970827
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:
19830830 - 19540828 - 19820813 - 19960731 - 20050825
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 27 - 31 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B B OREGON A B NRN CALIF A B
SRN CALIF A N IDAHO B N NEVADA A N
W MONTANA B A E MONTANA B N WYOMING B N
UTAH N A ARIZONA A A COLORADO A A
NEW MEXICO A A N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A N OKLAHOMA A B
N TEXAS A N S TEXAS A A W TEXAS A A
MINNESOTA A A IOWA A N MISSOURI A B
ARKANSAS A B LOUISIANA A N WISCONSIN A N
ILLINOIS A B MISSISSIPPI A N MICHIGAN A N
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A B 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 N
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN N A
AK S INT B A AK SO COAST B A AK PNHDL N B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 29 - SEP 04, 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A N
SRN CALIF N N IDAHO A N NEVADA A N
W MONTANA N N E MONTANA N N WYOMING N A
UTAH A A ARIZONA A N COLORADO N A
NEW MEXICO A A N DAKOTA B N S DAKOTA B A
NEBRASKA B A KANSAS N N OKLAHOMA A B
N TEXAS A N S TEXAS A A W TEXAS A N
MINNESOTA B N IOWA N N MISSOURI A B
ARKANSAS A B LOUISIANA A N WISCONSIN N N
ILLINOIS A N MISSISSIPPI A B MICHIGAN A N
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A B 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 N NEW JERSEY A A W VIRGINIA A N
MARYLAND A A DELAWARE A A VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B A AK WESTERN N A AK INT BSN A A
AK S INT A 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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