045
FXUS06 KWBC 061902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI SEPTEMBER 06 2024
6-10 DAY OUTLOOK FOR SEP 12 - 16 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 EASTERN NORTH AMERICA. UNDERNEATH THIS RIDGE, WEAK
TROUGHING AND A STATIONARY FRONTAL BOUNDARY IS FORECAST ACROSS THE SOUTHEAST.
BOTH THE GEFS AND ECENS HAVE TRENDED MORE AMPLIFIED WITH TROUGHING OVER THE
WESTERN CONUS PRIOR TO AND AT THE OUTSET OF THE PERIOD. WHILE THIS FEATURE IS
FORECAST TO WEAKEN DURING THE FORECAST PERIOD, IT IS EXPECTED TO HAVE SOME
INFLUENCE ON THE OVERALL PATTERN DOWNSTREAM BY LEADING TO INCREASED SOUTHERLY
FLOW OVER THE CENTRAL CONUS AND FURTHER AMPLIFYING THE RIDGE OVER THE EAST. A
PRONOUNCED RIDGE-TROUGH DIPOLE REMAINS FORECAST ACROSS THE NORTH-CENTRAL
PACIFIC WITH SHORTWAVE IMPULSES PREDICTED TO MOVE ACROSS ALASKA OVERTOP THE
RIDGE. TODAY’S MANUAL 6-10 DAY 500-HPA HEIGHT BLEND DEPICTS A +180 METER
POSITIVE HEIGHT ANOMALY CENTER OVER QUEBEC, WITH POSITIVE HEIGHT ANOMALIES
EXPANDING SOUTHWARD THROUGHOUT MUCH OF THE NORTH-CENTRAL AND NORTHEASTERN
CONUS. NEAR TO SLIGHTLY BELOW-NORMAL HEIGHTS ARE PREDICTED ACROSS THE SOUTHERN
MID-ATLANTIC, SOUTHEAST, INTERIOR WEST, 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 UPPER MISSISSIPPI VALLEY AND GREAT LAKES. NEAR- TO BELOW-NORMAL
TEMPERATURES ARE PREDICTED ACROSS MOST OF THE SOUTHERN MID-ATLANTIC, SOUTHEAST,
AND LOWER MISSISSIPPI VALLEY UNDERNEATH TROUGHING AND WEAKER HEIGHT ANOMALIES.
THE EXCEPTION IS OVER SOUTHERN FLORIDA WHERE ABOVE-NORMAL TEMPERATURES REMAIN
FAVORED SOUTH OF THE PREDICTED FRONTAL BOUNDARY. OVER ALASKA, ABOVE-NORMAL
TEMPERATURES ARE FAVORED OVER THE NORTHERN MAINLAND, WHILE NEAR- TO SLIGHTLY
BELOW-NORMAL TEMPERATURES ARE FORECAST OVER THE ALEUTIANS AND SOUTHERN ALASKA,
SUPPORTED BY THE UNCALIBRATED TEMPERATURE TOOLS. WHILE THE REFORECAST TOOLS
LEAN WARMER ACROSS SOUTHERN ALASKA, A TILT TOWARD COOLER TEMPERATURES 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.
MORE AMPLIFIED TROUGHING OVER THE WESTERN CONUS AT THE START OF THE PERIOD
FAVORS INCREASED CHANCES FOR ABOVE-NORMAL PRECIPITATION OVER THE NORTHERN
INTERMOUNTAIN THROUGH THE UPPER MISSISSIPPI VALLEY. ADDITIONALLY, INCREASED
SOUTHERLY RETURN FLOW AHEAD OF THE TROUGH FAVORS ELEVATED ABOVE NORMAL
PRECIPITATION PROBABILITIES ACROSS THE GREAT PLAINS AND ALONG THE GULF COAST.
THE NATIONAL HURRICANE CENTER (NHC) IS MONITORING A DISTURBANCE WITH A 40
PERCENT CHANCE OF DEVELOPING INTO A TROPICAL CYCLONE OVER THE WESTERN GULF OF
MEXICO BY THE END OF WEEK-1, WHICH MAY ALSO LEAD TO AN ENHANCEMENT OF
PRECIPITATION NEAR THE GULF COAST DURING THE FORECAST PERIOD. DIFFERENCES
BETWEEN THE WETTER ECENS REFORECAST TOOL AND DRIER GEFS SUPPORT INCREASED
CHANCES FOR NEAR-NORMAL PRECIPITATION NEAR THE WEST COAST AND EXTENDING INTO
THE FOUR CORNERS. NHC IS ALSO MONITORING A TROPICAL DISTURBANCE OVER THE
EASTERN PACIFIC, WHICH COULD CONTRIBUTE TO A MOISTURE SURGE BRINGING INCREASING
PRECIPITATION CHANCES INTO THE DESERT SOUTHWEST, ALTHOUGH UNCERTAINTY REMAINS
HIGH REGARDING THIS SCENARIO. RIDGING AND ABOVE-NORMAL 500-HPA HEIGHTS ACROSS
THE NORTHEAST FAVOR ENHANCED CHANCES FOR BELOW NORMAL-PRECIPITATION, WITH THE
HIGHEST CHANCES (GREATER THAN 50 PERCENT) EXTENDING FROM THE OHIO VALLEY INTO
THE NORTHEAST. 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-NORMAL PRECIPITATION IS FAVORED
ACROSS 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 LESS CONTINUITY COMPARED TO
YESTERDAY DUE TO MORE AMPLIFIED TROUGHING IN THE WEST.
8-14 DAY OUTLOOK FOR SEP 14 - 20 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 500-HPA HEIGHT
ANOMALIES FORECAST OVER THE NORTH-CENTRAL AND NORTHEASTERN CONUS IN THE MANUAL
HEIGHT BLEND. WEAK TROUGHING REMAINS FORECAST ACROSS THE SOUTHEAST, WITH AN
ASSOCIATED WEAKNESS IN THE HEIGHT FIELD. THE MID-LEVEL PATTERN ACROSS THE WEST
IS FAVORED TO BECOME MORE TRANSIENT AND VARIABLE, WITH OCCASIONAL SHORTAVE
IMPULSES DIGGING SOUTHWARD FROM ALASKA. NEAR-NORMAL HEIGHTS ARE PREDICTED FOR
THE PERIOD AS A WHOLE OVER THE WESTERN CONUS, WITH A TILT TOWARD BELOW-NORMAL
HEIGHTS OVER FAR WESTERN MAINLAND ALASKA. 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 GREAT LAKES AND NORTHEAST. THE RIDGE IS FORECAST TO
EXPAND AND PROGRESS EASTWARD, ALLOWING NEAR- TO ABOVE-NORMAL TEMPERATURES TO
BUILD FURTHER INTO THE SOUTHEAST COMPARED TO THE 6-10 DAY PERIOD. 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, WITH THE ECENS AND GEFS REFORECAST TOOLS FAVORING MORE OF A
TILT TOWARD ABOVE-NORMAL TEMPERATURES. 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 PARTS OF 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 EASTERN
CONUS DURING THE WEEK-2 PERIOD BENEATH A MID-LEVEL RIDGE, SUPPORTED BY MOST
FORECAST TOOLS AND ANALOG GUIDANCE. ABOVE-NORMAL PRECIPITATION IS FAVORED
ACROSS PORTIONS OF SOUTH FLORIDA ALONG A STALLED FRONTAL BOUNDARY. INTERMITTENT
TROUGHING FAVORS A TILT TOWARD ELEVATED NEAR-TO ABOVE-NORMAL PRECIPITATION
PROBABILITIES OVER MUCH OF THE WEST AND EXTENDING INTO THE GREAT PLAINS AND
MISSISSIPPI VALLEY UNDERNEATH INCREASED SOUTHERLY RETURN FLOW. ABOVE-NORMAL
PRECIPITATION IS ALSO FAVORED OVER ALASKA, GIVEN PERSISTENT TROUGHING OVER THE
STATE. 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.
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:
20030903 - 20060906 - 20010915 - 20080916 - 19880903
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:
20030902 - 20010911 - 20060905 - 19990915 - 20080916
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 12 - 16 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON N N NRN CALIF B N
SRN CALIF B N IDAHO B A NEVADA B N
W MONTANA B A E MONTANA A A WYOMING A A
UTAH A A ARIZONA A N COLORADO A N
NEW MEXICO A N N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA A A IOWA A N MISSOURI A N
ARKANSAS A A LOUISIANA N A WISCONSIN A N
ILLINOIS A B MISSISSIPPI N A MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A N ALABAMA N 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 B NEW JERSEY A B W VIRGINIA A B
MARYLAND A B DELAWARE A B VIRGINIA A B
N CAROLINA N N S CAROLINA N N GEORGIA N A
FL PNHDL N A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN N A AK WESTERN N A AK INT BSN A A
AK S INT N A AK SO COAST N N AK PNHDL N N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 14 - 20 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON N A NRN CALIF N N
SRN CALIF B N IDAHO N A NEVADA A N
W MONTANA N A E MONTANA A A WYOMING A N
UTAH A N ARIZONA A N COLORADO A N
NEW MEXICO A N N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A 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 B
TENNESSEE A B ALABAMA A N NEW YORK A B
VERMONT A B NEW HAMP A B MAINE A B
MASS A B 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 A N GEORGIA N N
FL PNHDL N N FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B A AK WESTERN A A AK INT BSN A A
AK S INT N A AK SO COAST N A AK PNHDL N N
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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