493
FXUS06 KWBC 291902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU AUGUST 29 2024
6-10 DAY OUTLOOK FOR SEP 04 - 08 2024
DURING EARLY SEPTEMBER, THE GEFS, ECENS, CMCE ARE CONSISTENT AND IN GOOD
AGREEMENT DEPICTING A HIGH AMPLITUDE LONGWAVE PATTERN WITH A TROUGH CENTERED
OVER WESTERN MAINLAND ALASKA AND A DOWNSTREAM RIDGE ACROSS THE WESTERN
CONTIGUOUS U.S. (CONUS). THE AMPLIFIED MID-LEVEL RIDGE WITH POSITIVE HEIGHT
DEPARTURES SUPPORTS INCREASED ABOVE-NORMAL TEMPERATURE PROBABILITIES THROUGHOUT
THE WESTERN CONUS, NORTHERN TO CENTRAL GREAT PLAINS, AND PARTS OF THE UPPER
MISSISSIPPI VALLEY. A MORE TRANSIENT PATTERN IS EXPECTED ACROSS THE EASTERN
CONUS, BUT FOR THE SECOND CONSECUTIVE DAY THE GEFS AND ECENS FEATURE A
REAMPLIFICATION OF A 500-HPA TROUGH FOR THIS REGION BY DAY 8 (SEP 6). THIS
QUICK RETURN OF ANOMALOUS TROUGHING FAVORS BELOW-NORMAL TEMPERATURES ACROSS A
MAJORITY OF THE EASTERN CONUS ALONG WITH THE OHIO AND TENNESSEE VALLEYS, MIDDLE
TO LOWER MISSISSIPPI VALLEY, AND SOUTHERN GREAT PLAINS. FARTHER TO THE SOUTH
WHERE COLD AIR ADVECTION IS UNLIKELY, ABOVE-NORMAL TEMPERATURES ARE FAVORED
ALONG THE GULF COAST AND FLORIDA.
A RESIDUAL FRONT AND AN INCREASED CHANCE FOR SURFACE LOW DEVELOPMENT ANYWHERE
ALONG OR NEAR THIS FRONT FAVORS ABOVE-NORMAL PRECIPITATION ACROSS MUCH OF
TEXAS, LOWER MISSISSIPPI VALLEY, AND SOUTHEAST. THE AMPLIFIED 500-HPA RIDGE
CENTERED OVER THE ROCKIES SUPPORTS ELEVATED BELOW-NORMAL PRECIPITATION
PROBABILITIES FOR MUCH OF THE NORTH-CENTRAL AND WESTERN CONUS. MODEL GUIDANCE
GENERALLY FAVORS A LACK OF LATE SEASON MONSOON RAINFALL FOR THE DESERT
SOUTHWEST.
THE GEFS, ECENS, AND CMCE AGREE THAT A 500-HPA TROUGH PERSISTS OVER MAINLAND
ALASKA WHICH FAVORS NEAR TO ABOVE-NORMAL PRECIPITATION FOR THE STATE.
PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION EXCEED 50 PERCENT FOR SOUTHEASTERN
ALASKA DUE TO ENHANCED ONSHORE FLOW AND THE ENSEMBLE MEANS PREDICT 5-DAY TOTAL
AMOUNTS EXCEEDING 4 INCHES. THE 6-10 DAY TEMPERATURE OUTLOOK GENERALLY FOLLOWS
THE GEFS AND ECMWF REFORECAST TOOLS AND DEPICTS INCREASED CHANCES FOR BELOW
(ABOVE)-NORMAL PROBABILITIES ACROSS COASTAL WESTERN ALASKA AND THE ALEUTIANS
(EASTERN MAINLAND ALASKA AND SOUTHEASTERN ALASKA).
BASED ON THE GEFS AND ECENS, NEAR OR ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR
HAWAII. ELEVATED BELOW-NORMAL PRECIPITATION PROBABILITIES ARE FORECAST FOR
HAWAII.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 30% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY
8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: FORECAST CONFIDENCE: ABOVE
AVERAGE, 4 OUT OF 5, DUE TO IMPROVED MODEL AGREEMENT ON THE LONGWAVE PATTERN.
8-14 DAY OUTLOOK FOR SEP 06 - 12 2024
THE GEFS, ECENS, AND CMCE ARE IN GOOD AGREEMENT AND DEPICT AN AMPLIFIED 500-HPA
RIDGE EXTENDING FROM THE DESERT SOUTHWEST NORTH TO THE CANADIAN PRAIRIES WITH A
DOWNSTREAM TROUGH CENTERED OVER THE OHIO AND TENNESSEE VALLEYS. THE LARGEST
MODEL DIFFERENCE IN THE LONGWAVE PATTERN EXISTS OVER THE GULF OF ALASKA WITH
THE PLACEMENT AND AMPLITUDE OF A 500-HPA TROUGH. THE ECENS AND CMCE HAVE THE
TROUGH CLOSER TO THE PACIFIC NORTHWEST, WHILE THE GEFS FEATURES A TROUGH AXIS
WELL TO THE WEST OVER THE NORTH PACIFIC. NEITHER MODEL SOLUTION IS PREFERRED AT
THIS TIME AND THE MANUAL 500-HPA HEIGHT BLEND WAS CREATED USING CLOSE TO EQUAL
WEIGHTING OF THE GEFS, ECENS, AND CMCE. DUE TO THE AMPLIFIED 500-HPA RIDGE,
ABOVE-NORMAL TEMPERATURES ARE FAVORED THROUGHOUT THE WESTERN CONUS WITH THE
LARGEST PROBABILITIES (ABOVE 80 PERCENT) FORECAST ACROSS NORTHERN MONTANA.
ALTHOUGH INCREASED ABOVE-NORMAL TEMPERATURE PROBABILITIES EXTEND EAST TO PARTS
OF THE GREAT PLAINS AND NORTHERN MINNESOTA, FORECAST CONFIDENCE IS LOWER THAN
THE WESTERN CONUS. GIVEN THE MORE AMPLIFIED TROUGH PREDICTED OVER THE
EAST-CENTRAL CONUS, MOST TEMPERATURE TOOLS HAVE TRENDED COLDER FROM THE
MISSISSIPPI VALLEY EAST TO THE EAST COAST. ALONG THE GULF COAST AND ACROSS
FLORIDA, ABOVE-NORMAL TEMPERATURES REMAIN MORE LIKELY.
THE NATIONAL HURRICANE CENTER (NHC) IS MONITORING A TROPICAL WAVE OVER THE
CENTRAL TROPICAL ATLANTIC. AS OF 2PM EDT ON AUGUST 29, THE NHC STATES THAT THIS
WAVE HAS A 40 PERCENT CHANCE OF BECOMING A TROPICAL CYCLONE (TC) DURING THE
NEXT WEEK. LATER IN WEEK-2, THIS POTENTIAL TC MAY TRACK WESTWARD TO THE GULF OF
MEXICO OR APPROACH THE SOUTHEASTERN CONUS. HOWEVER, SPREAD AMONG THE GEFS AND
ECENS IS VERY LARGE ON THAT TRACK.
THE WEEK-2 PRECIPITATION OUTLOOK IS BASED ON THE GEFS AND ECMWF REFORECAST
TOOLS, UNCALIBRATED MODEL OUTPUT, AND THE ANALOG TOOL DERIVED FROM THE MANUAL
500-HPA HEIGHT BLEND. ALONG AND DOWNSTREAM OF THE MID-LEVEL RIDGE ALOFT, A
LARGE AREA WITH FAVORED DRYNESS IS FORECAST FOR THE INTERIOR WEST, NORTHERN
ROCKIES, MUCH OF THE GREAT PLAINS, MIDDLE TO UPPER MISSISSIPPI VALLEY, AND
MIDWEST. THE TROUGH OVER THE OHIO AND TENNESSEE VALLEYS SUPPORTS ELEVATED
ABOVE-NORMAL PRECIPITATION PROBABILITIES FOR THE EAST COAST. AT THE BASE OF AN
AMPLIFYING MID-LEVEL TROUGH, ELEVATED ABOVE-NORMAL PRECIPITATION PROBABILITIES
ARE ALSO FORECAST FOR PARTS OF THE LOWER MISSISSIPPI VALLEY AND SOUTHERN TEXAS.
SINCE THE ECENS AND CMCE HAVE A TROUGH CLOSER TO THE WEST COAST, A SLIGHT TILT
TOWARDS WET IS FORECAST FOR COASTAL OREGON AND WASHINGTON.
AN AMPLIFIED 500-HPA TROUGH AND ENHANCED ONSHORE FLOW FAVOR ABOVE-NORMAL
PRECIPITATION ACROSS EASTERN MAINLAND ALASKA AND SOUTHEASTERN ALASKA. MODEL
GUIDANCE REMAINS CONSISTENT AND IN GOOD AGREEMENT WITH INCREASED BELOW
(ABOVE)-NORMAL TEMPERATURE PROBABILITIES FOR COASTAL WESTERN ALASKA AND THE
ALEUTIANS (EASTERN MAINLAND ALASKA AND SOUTHEASTERN ALASKA).
BASED ON THE GEFS AND ECENS, NEAR TO ABOVE-NORMAL TEMPERATURES AND NEAR TO
BELOW-NORMAL PRECIPITATION ARE FAVORED FOR 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: AVERAGE, 3 OUT OF 5, DUE TO GOOD
AGREEMENT AMONG MOST OF THE TEMPERATURE AND PRECIPITATION TOOLS OFFSET BY
UNCERTAINTY ON THE AMPLITUDE OF THE EASTERN CONUS TROUGH AND POTENTIAL EFFECTS
FROM A TC LATER IN WEEK-2.
FORECASTER: BRAD PUGH
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:
20050824 - 20050905 - 20020830 - 19530810 - 20060830
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:
20050907 - 20050823 - 20020829 - 19530808 - 19980820
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 04 - 08 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A N
SRN CALIF A B IDAHO A B NEVADA A B
W MONTANA A B E MONTANA A B WYOMING A N
UTAH A B ARIZONA A B COLORADO A N
NEW MEXICO A N N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS N N OKLAHOMA B N
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA A B IOWA B B MISSOURI B B
ARKANSAS B A LOUISIANA B A WISCONSIN N B
ILLINOIS B B MISSISSIPPI B A MICHIGAN N B
INDIANA B B OHIO B B KENTUCKY B A
TENNESSEE B A ALABAMA B A NEW YORK B N
VERMONT N N NEW HAMP N N MAINE N N
MASS B N CONN B N RHODE IS B N
PENN B N NEW JERSEY B N W VIRGINIA B N
MARYLAND B N DELAWARE B N VIRGINIA B A
N CAROLINA B A S CAROLINA B A GEORGIA B A
FL PNHDL A A FL PENIN A A AK N SLOPE N N
AK ALEUTIAN B N AK WESTERN N N AK INT BSN A N
AK S INT A A AK SO COAST A A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 06 - 12 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A N NRN CALIF A N
SRN CALIF A N IDAHO A B NEVADA A N
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A B ARIZONA A N COLORADO A N
NEW MEXICO A N N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS N N OKLAHOMA N B
N TEXAS N N S TEXAS N N W TEXAS A N
MINNESOTA A B IOWA N B MISSOURI B B
ARKANSAS B B LOUISIANA B N WISCONSIN B B
ILLINOIS B B MISSISSIPPI B N MICHIGAN B B
INDIANA B B OHIO B B KENTUCKY B N
TENNESSEE B N ALABAMA B A NEW YORK B N
VERMONT B A NEW HAMP B A MAINE N A
MASS B A CONN B A RHODE IS B A
PENN B N NEW JERSEY B A W VIRGINIA B N
MARYLAND B A DELAWARE B A VIRGINIA B A
N CAROLINA B A S CAROLINA B A GEORGIA B 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 N
AK S INT A A AK SO COAST A A AK PNHDL A 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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