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FXUS06 KWBC 201929
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE AUGUST 20 2024
6-10 DAY OUTLOOK FOR AUG 26 - 30 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
LOW-AMPLITUDE RIDGE IS DEPICTED ACROSS THE VICINITY OF THE GREAT LAKES. TODAY’S
MANUAL HEIGHT BLEND DOES NOT DEPICT A 594-DM HEIGHT CONTOUR OVER THE
SOUTHWESTERN AND SOUTH-CENTRAL CONUS LIKE IT DID YESTERDAY. 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
PACIFIC NORTHWEST COAST (BOTH ANOMALIES EXCEEDING +90 M). A DEEP ANOMALOUS
TROUGH IS PREDICTED TO BE CENTERED OVER THE EASTERN BERING SEA AND WESTERN
ALASKA, ACCOMPANIED BY NEGATIVE 500-HPA HEIGHT ANOMALIES ACROSS MOST OF THE
STATE. THE EXCEPTION IS SOUTHEAST ALASKA WHERE MOSTLY POSITIVE HEIGHT ANOMALIES
ARE PREDICTED, PART OF AN UNDERCUTTING FLAT RIDGE OVER THE GULF OF ALASKA THAT
IS EXPECTED TO EXTEND EASTWARD INTO BRITISH COLUMBIA AND THE PACIFIC NORTHWEST.
NEAR THE HAWAIIAN ARCHIPELAGO, MID-LEVEL HEIGHTS ARE PREDICTED TO BE NEAR OR
SLIGHTLY ABOVE NORMAL. ANOMALY CORRELATION SCORES OVER THE PAST 60 DAYS SHOW
THE ECENS HAS A SLIGHT EDGE OVER THE GEFS AND CMCE ENSEMBLE MEANS.
THE 6-10 DAY TEMPERATURE OUTLOOK FAVORS BELOW NORMAL TEMPERATURES OVER NORTHERN
AND CENTRAL PORTIONS OF THE ROCKIES AND THE NORTHERN HIGH PLAINS, CONSISTENT
WITH MANY OF THE TEMPERATURE TOOLS. THE RAW AND BIAS-CORRECTED TEMPERATURE
TOOLS DEPICT A SOMEWHAT BROADER COVERAGE OF FAVORED BELOW NORMAL TEMPERATURES
COMPARED TO THE REFORECAST TEMPERATURE TOOLS. MANY OF THE TEMPERATURE TOOLS
FAVOR ABOVE NORMAL TEMPERATURES OVER THE PACIFIC COAST STATES, ASSOCIATED IN
PART WITH THE ANOMALOUS RIDGE FORECASTED IN THE VICINITY OF BRITISH
COLUMBIA.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 OHIO VALLEY. FOR ALASKA,
NEARLY ALL TOOLS AGREE ON FAVORED BELOW NORMAL TEMPERATURES, CONSISTENT WITH
THE BROAD MID-LEVEL TROUGH AND ASSOCIATED NEGATIVE HEIGHT ANOMALIES OVER THAT
REGION, WITH THE EXCEPTION OF NEAR NORMAL TEMPERATURES FOR MOST OF THE
PANHANDLE REGION, AND ALSO MOST OF NORTHEASTERN MAINLAND ALASKA. 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 ROCKIES EASTWARD TO THE UPPER
MISSISSIPPI VALLEY. THIS IS RELATED TO THE EXPECTED PASSAGE OF A LOW PRESSURE
SYSTEM PRIMARILY OVER THE CANADIAN PRAIRIES EARLIER IN THE FORECAST PERIOD.
ABOVE NORMAL PRECIPITATION IS ALSO FAVORED OVER THE FLORIDA PENINSULA, SOUTHERN
AND SOUTHWESTERN TEXAS, MUCH OF THE FOUR CORNERS REGION, AND PARTS OF FAR
SOUTHEASTERN CALIFORNIA. THESE AREAS GENERALLY COINCIDE WITH THE SOUTHERN AND
WESTERN FLANKS OF THE AZORES-BERMUDA HIGH, WITH MONSOON PRECIPITATION EXPECTED
FOR THE SOUTHWEST CONUS. BELOW NORMAL PRECIPITATION IS FAVORED FOR A WIDESPREAD
REGION THAT EXTENDS ACROSS MUCH OF THE EAST AND INTO THE SOUTH-CENTRAL PLAINS,
COINCIDENT WITH THE BROAD MID-LEVEL RIDGE AND POSITIVE HEIGHT DEPARTURES
PREDICTED OVER THAT REGION. BELOW NORMAL PRECIPITATION IS ALSO FAVORED FROM THE
NORTHERN PACIFIC COAST EASTWARD INTO THE NORTH-CENTRAL ROCKIES, 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 A TROPICAL SYSTEM. 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 28 - SEP 03, 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 FIELD, MOST OF THE CONUS IS EXPECTED TO BE UNDER ABOVE
NORMAL 500-HPA HEIGHTS, WITH THE TWO LARGER POSITIVE HEIGHT ANOMALY CENTERS
(>60 M) LOCATED OVER THE SOUTHERN CANADIAN MARITIMES AND NEAR THE BRITISH
COLUMBIA COAST, BOTH OF WHICH ARE SITUATED NEAR 50N LATITUDE. IN ALASKA, A
TROUGH IS STILL PREDICTED OVER THE EASTERN BERING SEA AND WESTERN ALASKA, BUT
THE ACCOMPANYING NEGATIVE HEIGHT DEPARTURES HAVE DECREASED TO -30 METERS OR
LESS. THE MANUAL HEIGHT BLEND ALSO SHOWS RISING 500-HPA HEIGHTS OVER MUCH OF
EASTERN ALASKA COMPARED TO YESTERDAY, ASSOCIATED WITH THE ANOMALOUS RIDGE
CENTERED NEAR BRITISH COLUMBIA. 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, RAW, AND
BIAS-CORRECTED TEMPERATURE GUIDANCE. MAXIMUM PROBABILITIES FAVORING ABOVE
NORMAL TEMPERATURES EXCEED 60% OVER THE PACIFIC NORTHWEST AND SOUTHERN FLORIDA.
A LARGE AREA OF FAVORED NEAR NORMAL TEMPERATURES, BASED ON MIXED AND/OR WEAK
SIGNALS AMONG THE TEMPERATURE TOOLS, EXTENDS FROM NORTH-CENTRAL AND CENTRAL
PORTIONS OF THE ROCKIES EASTWARD ACROSS MOST OF THE NORTHERN AND CENTRAL
PLAINS, AND APPROXIMATELY THE UPPER HALF OF THE MISSISSIPPI VALLEY. PART OF THE
DISCREPANCY AMONG THE TEMPERATURE TOOLS IS RELATED TO THE BIAS-CORRECTED
TEMPERATURE FORECASTS WHICH ARE TRYING TO CORRECT FOR RECENT ENSEMBLE FORECASTS
THAT HAVE RECENTLY SHOWN A WARM BIAS OVER MUCH OF THIS REGION. IN ALASKA, BELOW
NORMAL TEMPERATURES ARE FAVORED OVER THE WESTERN THIRD OF THE STATE, NEAR
NORMAL TEMPERATURES ARE FAVORED OVER APPROXIMATELY THE MIDDLE THIRD OF THE
STATE, AND ABOVE NORMAL TEMPERATURES ARE FAVORED OVER MOST OF THE EASTERN THIRD
OF ALASKA. THIS IS CONSISTENT WITH PREDICTED RISING MID-LEVEL HEIGHTS ACROSS
EASTERN ALASKA, AND THE CONTINUED PRESENCE OF A MID-LEVEL TROUGH OVER THE
EASTERN BERING SEA AND WESTERN ALASKA. 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 IS 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
NORTHEAST CONUS WHERE A FRONTAL SYSTEM AND ACCOMPANYING MID-LEVEL TROUGH ARE
PREDICTED TO APPROACH FROM SOUTHERN CANADA AND THE GREAT LAKES REGION. ODDS
FAVOR BELOW NORMAL PRECIPITATION FROM THE SOUTH-CENTRAL PLAINS TO THE SOUTHERN
GREAT LAKES REGION. THIS IS MORE IN LINE WITH THE RAW PRECIPITATION TOOLS THAN
THE REFORECAST PRECIPITATION TOOLS WHICH APPEAR TO BE TOO WET TODAY. OVER THE
PACIFIC NORTHWEST, BELOW NORMAL PRECIPITATION IS FAVORED IN PROXIMITY TO THE
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 - 19960731 - 19820814 - 19970828
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:
19540827 - 19830830 - 19820813 - 19960730 - 19730822
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 26 - 30 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A N
SRN CALIF A N IDAHO B B NEVADA A B
W MONTANA B N E MONTANA B A WYOMING B N
UTAH B N ARIZONA A A COLORADO A N
NEW MEXICO A A N DAKOTA A A S DAKOTA A N
NEBRASKA A N KANSAS A B OKLAHOMA A B
N TEXAS A N S TEXAS A A W TEXAS A N
MINNESOTA A N IOWA A N MISSOURI A B
ARKANSAS A B LOUISIANA A N WISCONSIN A N
ILLINOIS A B MISSISSIPPI A B MICHIGAN A B
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 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 N FL PENIN A A AK N SLOPE B A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST B A AK PNHDL N N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 28 - SEP 03, 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A N NRN CALIF A A
SRN CALIF A A IDAHO A A NEVADA A A
W MONTANA A N E MONTANA N N WYOMING N A
UTAH A A ARIZONA A A COLORADO N A
NEW MEXICO A A N DAKOTA N N S DAKOTA N N
NEBRASKA N N KANSAS N B OKLAHOMA A B
N TEXAS A N S TEXAS A A W TEXAS A N
MINNESOTA N N IOWA N N MISSOURI N B
ARKANSAS A B LOUISIANA A N WISCONSIN N N
ILLINOIS N B MISSISSIPPI A N MICHIGAN A N
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A N ALABAMA A N NEW YORK A N
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 N W VIRGINIA A N
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN A A
AK S INT N A AK SO COAST B A AK PNHDL A B
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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