442
FXUS06 KWBC 051902
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 05 2024
6-10 DAY OUTLOOK FOR SEP 11 - 15 2024
DYNAMICAL MODELS REMAIN IN GOOD AGREEMENT REGARDING THE 500-HPA CIRCULATION
PATTERN ACROSS NORTH AMERICA DURING THE 6-10 DAY PERIOD. ANOMALOUS MID-LEVEL
RIDGING IS PREDICTED ACROSS NORTH-CENTRAL NORTH AMERICA, WITH A GRADUAL
EASTWARD SHIFT WITH TIME. UNDERNEATH THIS RIDGE, WEAK TROUGHING AND AN
ASSOCIATED FRONTAL BOUNDARY IS FORECAST ACROSS THE SOUTHEAST. THE PATTERN
ACROSS THE PACIFIC IS FAVORED TO BE MORE TRANSIENT, WITH RIDGING FORECAST OVER
THE CENTRAL PACIFIC AND NEAR THE ALEUTIANS, BUT WITH MORE TROUGHING OVER ALASKA
AND THE WEST COAST OF THE CONUS. TODAY’S MANUAL 6-10 DAY 500-HPA HEIGHT BLEND
DEPICTS A +180 METER POSITIVE HEIGHT ANOMALY CENTER OVER SOUTHERN HUDSON BAY,
WITH POSITIVE HEIGHT ANOMALIES EXPANDING SOUTHWARD THROUGHOUT MUCH OF THE
NORTHERN AND CENTRAL PLAINS, GREAT LAKES, AND NORTHEASTERN CONUS. NEAR TO
SLIGHTLY BELOW-NORMAL HEIGHTS ARE PREDICTED ACROSS THE SOUTHERN MID-ATLANTIC,
SOUTHEAST, PACIFIC NORTHWEST, AND MOST OF ALASKA (EXCLUDING THE ALEUTIANS WHERE
ABOVE-NORMAL HEIGHTS ARE FORECAST). ABOVE-NORMAL 500-HPA HEIGHTS ARE PREDICTED
OVER HAWAII.
ENHANCED CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE STRONGLY FAVORED BENEATH THE
MID-LEVEL RIDGE ACROSS MUCH OF THE NORTHERN AND CENTRAL U.S. DURING THE 6-10
DAY PERIOD. CHANCES EXCEED 80 PERCENT FOR ABOVE-NORMAL TEMPERATURES ACROSS
PORTIONS OF THE NORTHERN PLAINS AND UPPER MIDWEST. BELOW-NORMAL TEMPERATURES
ARE PREDICTED ACROSS MOST OF THE SOUTHEASTERN CONUS THROUGH SOUTHERN TEXAS
UNDERNEATH TROUGHING AND WEAKER HEIGHT ANOMALIES. THE EXCEPTION IS OVER
SOUTHERN FLORIDA WHERE ABOVE-NORMAL TEMPERATURES REMAIN FAVORED SOUTH OF THE
PREDICTED FRONTAL BOUNDARY. IN ALASKA, ABOVE-NORMAL TEMPERATURES ARE FAVORED
OVER THE NORTHERN MAINLAND ALASKA, WHILE BELOW-NORMAL TEMPERATURES ARE FORECAST
OVER THE ALEUTIANS AND SOUTHEAST ALASKA, SUPPORTED BY THE UNCALIBRATED
TEMPERATURE TOOLS. WHILE THE REFORECAST TOOLS LEAN WARMER ACROSS SOUTHEAST
ALASKA, A TILT TOWARD BELOW-NORMAL IS PREFERRED GIVEN THE ANTICIPATED INCREASE
IN ONSHORE FLOW AND MOISTURE ACROSS THE REGION. IN HAWAII, ABOVE-NORMAL
TEMPERATURES ARE FAVORED, CONSISTENT WITH THE TEMPERATURE CONSOLIDATION TOOL.
MUCH OF THE CONUS IS FAVORED TO HAVE BELOW-NORMAL PRECIPITATION DURING THE 6-10
DAY PERIOD DUE TO THE RIDGING AND ABOVE-NORMAL 500-HPA HEIGHTS, WITH THE
HIGHEST CHANCES (GREATER THAN 50 PERCENT) EXTENDING FROM THE MIDWEST INTO THE
NORTHEAST. HOWEVER, ABOVE-NORMAL PRECIPITATION IS FAVORED ALONG THE GULF COAST
THROUGH THE SOUTHEAST AS A STALLED FRONTAL BOUNDARY FAVORS PERIODS OF ENHANCED
PRECIPITATION. THERE REMAINS SOME CONCERN FOR A TROPICAL SYSTEM TO MOVE INTO
THE GULF OF MEXICO BY THE END OF WEEK-1 AND INTO WEEK-2 BUT CONFIDENCE REMAINS
LOW. TROUGHING NEAR THE NORTHWESTERN CONUS MAY BRING ONSHORE FLOW AND INCREASED
CHANCES FOR PRECIPITATION TO THE REGION. ABOVE-NORMAL PRECIPITATION
PROBABILITIES ARE ELEVATED OVER MOST OF ALASKA DUE TO TROUGHING AND
INTERMITTENT WAVES OF SURFACE LOW PRESSURE MOVING THROUGH THE REGION. IN
HAWAII, NEAR- TO ABOVE-NORMAL PRECIPITATION IS SLIGHTLY FAVORED ACROSS MOST OF
THE STATE.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON
DAY 8, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF
TODAY'S OPERATIONAL 0Z ECMWF 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. GOOD
AGREEMENT AMONG THE DYNAMICAL TOOLS, OFFSET BY A MORE PROGRESSIVE PATTERN BY
THE END OF THE PERIOD.
8-14 DAY OUTLOOK FOR SEP 13 - 19 2024
THE WEEK-2 MID-LEVEL CIRCULATION PATTERN IS FAIRLY CONSISTENT WITH THAT OF THE
6-10 DAY PERIOD, WITH AN EASTWARD SHIFT IN SOME OF THE FEATURES. ANOMALOUS
RIDGING IS FORECAST ACROSS EASTERN CANADA, WITH POSITIVE HEIGHT ANOMALIES OVER
THE NORTHERN CONUS IN THE MANUAL HEIGHT BLEND. WEAK TROUGHING REMAINS FORECAST
ACROSS THE SOUTHEAST, WITH AN ASSOCIATED WEAKNESS IN THE HEIGHT FIELD. THE MOST
NOTABLE DIFFERENCE IS ACROSS THE WEST, WHERE THE GEFS REBUILDS RIDGING AND
POSITIVE HEIGHT ANOMALIES BY THE END OF WEEK-2, WHILE THE ECENS AND CMCE
MAINTAIN A WEAKER FLOW PATTERN WITH SOME NEGATIVE HEIGHT ANOMALIES ACROSS
WESTERN NORTH AMERICA. THE MANUAL HEIGHT BLEND DEPICTS NEAR-NORMAL HEIGHTS
ACROSS THE WESTERN CONUS, WITH BELOW-NORMAL HEIGHTS OVER MAINLAND AND SOUTHEAST
ALASKA WHERE THERE IS BETTER MODEL AGREEMENT FOR TROUGHING DURING THE PERIOD.
ABOVE-NORMAL HEIGHTS ARE FORECAST OVER THE WESTERN ALEUTIANS AND HAWAII
UNDERNEATH MORE RIDGING OVER THE CENTRAL PACIFIC.
ABOVE-NORMAL TEMPERATURES REMAIN FAVORED FOR MUCH OF THE CONUS DURING WEEK-2
BENEATH THE FORECAST RIDGE ACROSS THE REGION, WITH PROBABILITIES EXCEEDING 70
PERCENT ACROSS PARTS OF THE UPPER MIDWEST AND GREAT LAKES. THE RIDGE IS
FORECAST TO EXPAND AND PROGRESS EASTWARD, REPLACING BELOW-NORMAL TEMPERATURES
FAVORED IN THE 6-10 DAY WITH NEAR- TO ABOVE-NORMAL TEMPERATURES ACROSS THE
SOUTHEASTERN CONUS. NEAR- TO BELOW-NORMAL TEMPERATURES ARE FORECAST OVER THE
WEST COAST ASSOCIATED WITH TROUGHING, ALTHOUGH THE TEMPERATURE TREND OVER THE
WEST IS MORE UNCERTAIN LATER IN THE PERIOD DUE TO THE AFOREMENTIONED MODEL
DIFFERENCES IN THE MID-LEVEL PATTERN EVOLUTION. AS WITH THE 6-10 DAY PERIOD,
ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF NORTHERN MAINLAND ALASKA,
WHILE BELOW-NORMAL TEMPERATURES ARE LIKELY OVER THE ALEUTIANS AND SOUTHEAST
ALASKA DUE TO CONTINUED SUPPORT FROM THE UNCALIBRATED TEMPERATURE TOOLS. IN
HAWAII, ABOVE-NORMAL TEMPERATURES ARE FAVORED, CONSISTENT WITH THE TEMPERATURE
CONSOLIDATION TOOL.
BELOW-NORMAL PRECIPITATION CHANCES REMAIN ELEVATED ACROSS MOST OF THE CENTRAL,
AND NORTHEASTERN CONUS DURING THE WEEK-2 PERIOD BENEATH AN EXPANDING MID-LEVEL
RIDGE AND BEHIND A WEAK TROUGH AXIS NEAR THE SOUTHEAST. ABOVE-NORMAL
PRECIPITATION IS FAVORED ACROSS PORTIONS OF THE GULF COAST AND SOUTHEAST AT THE
BASE OF A TROUGH AND WITH CONTINUED CHANCES FOR A TROPICAL DISTURBANCE TO BRING
UNSETTLED WEATHER INTO THE REGION. A TROUGH NEAR THE WEST COAST FAVORS
INCREASED CHANCES FOR ABOVE-NORMAL PRECIPITATION OVER THE NORTHWESTERN CONUS,
ALTHOUGH THESE PROBABILITIES ARE DIMINISHED COMPARED TO YESTERDAY AS THE
STRONGEST FORCING LIFTS NORTHWARD. THE NATIONAL HURRICANE CENTER IS CURRENTLY
MONITORING A TROPICAL DISTURBANCE OVER THE EASTERN PACIFIC, WHICH COULD
CONTRIBUTE TO A MOISTURE SURGE AROUND THE MIDDLE OF WEEK-2 BRINGING INCREASING
PRECIPITATION CHANCES INTO THE DESERT SOUTHWEST. THIS IS STILL UNCERTAIN, AND
ONLY A SLIGHT TILT TOWARD INCREASED ABOVE-NORMAL PRECIPITATION PROBABILITIES IS
NOTED ACROSS SOUTHERN ARIZONA AND CALIFORNIA, WITH BELOW-NORMAL PRECIPITATION
CHANCES SLIGHTLY ENHANCED ACROSS THE FOUR CORNERS. ABOVE-NORMAL PRECIPITATION
IS ALSO FAVORED OVER ALASKA, GIVEN PERSISTENT TROUGHING OVER THE STATE. NEAR-
TO ABOVE-NORMAL PRECIPITATION IS FORECAST OVER HAWAII.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 40% OF TODAY'S 6Z 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: AVERAGE, 3 OUT OF 5, FAIR
AGREEMENT AMONG THE TOOLS OFFSET BY A LESS AMPLIFIED AND PROGRESSIVE HEIGHT
PATTERN LATER IN THE PERIOD, AND DIFFERENCES EMERGING OVER THE WESTERN CONUS.
FORECASTER: THOMAS COLLOW
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:
19950906 - 19530908 - 20030903 - 20010915 - 19740918
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:
19950905 - 20010913 - 20030902 - 19530907 - 19790914
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 11 - 15 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON N A NRN CALIF N A
SRN CALIF N N IDAHO A A NEVADA A B
W MONTANA A A E MONTANA A A WYOMING A N
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A N S DAKOTA A N
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS N A S TEXAS B A W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA B A WISCONSIN A B
ILLINOIS A B MISSISSIPPI B A MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA B 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 B W VIRGINIA A B
MARYLAND A B DELAWARE N B VIRGINIA A B
N CAROLINA N B S CAROLINA B N GEORGIA B A
FL PNHDL B A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B N AK WESTERN N A AK INT BSN A A
AK S INT N A AK SO COAST N A AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 13 - 19 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON N A NRN CALIF N N
SRN CALIF N N IDAHO A A NEVADA A N
W MONTANA A A E MONTANA A A WYOMING A N
UTAH A B ARIZONA A N COLORADO A N
NEW MEXICO A N N DAKOTA A N S DAKOTA A N
NEBRASKA A N KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS A A W TEXAS A N
MINNESOTA A N 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 B NEW HAMP A B MAINE A B
MASS A N CONN A N RHODE IS A N
PENN A B NEW JERSEY A N W VIRGINIA A B
MARYLAND A B DELAWARE A N VIRGINIA A B
N CAROLINA A N S CAROLINA N N GEORGIA N A
FL PNHDL N A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B N AK WESTERN N A AK INT BSN A A
AK S INT N A AK SO COAST N A AK PNHDL B 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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