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FXUS06 KWBC 191914
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU OCTOBER 19 2023
6-10 DAY OUTLOOK FOR OCT 25 - 29 2023
TODAY’S ENSEMBLE MEAN MODELS ARE IN VERY GOOD AGREEMENT REGARDING THEIR
PREDICTION OF AN AMPLIFIED WAVETRAIN OVER THE PACIFIC-NORTH AMERICA REGION
DURING THE 6-10 DAY PERIOD. MID-LEVEL TROUGHS ARE FORECAST OVER THE CENTRAL
PACIFIC (CENTERED NORTH OF HAWAII), AND THE WEST-CENTRAL CONTIGUOUS U.S.
(CONUS). MID-LEVEL RIDGES ARE DEPICTED OVER THE EASTERN PACIFIC/ALASKA, AND THE
EASTERN CONUS, WITH THE LATTER FEATURE FORECAST TO RAPIDLY DE-AMPLIFY, GIVING
WAY TO INCREASING CYCLONIC CURVATURE ACROSS THE GREAT LAKES AND NORTHEAST. THE
MANUAL HEIGHT BLEND DEPICTS THE LARGEST NEGATIVE 500-HPA HEIGHT DEPARTURES
(ABOUT -130 METERS) OVER THE CENTRAL PACIFIC, WITH THE LARGEST POSITIVE 500-HPA
HEIGHT DEPARTURES (ABOUT +280 METERS) OVER SOUTH-CENTRAL ALASKA. NEAR TO
SLIGHTLY ABOVE NORMAL MID-LEVEL HEIGHTS ARE EXPECTED OVER HAWAII.
THE MOST CHALLENGING ASPECT OF TODAY’S 6-10 DAY TEMPERATURE OUTLOOK IS
ANTICIPATING THE SPATIAL EXTENT OF ARCTIC AIR ACROSS THE WESTERN AND CENTRAL
CONUS, BUT ESPECIALLY THE SOUTHWEST AND SOUTHERN GREAT PLAINS. THE GEFS
REFORECAST-CALIBRATED TEMPERATURE TOOL FAVORS BELOW NORMAL MEAN TEMPERATURES
ACROSS MOST OF THE WESTERN AND CENTRAL CONUS, WHEREAS THE ECMWF AND CANADIAN
ENSEMBLE MEAN REFORECASTS FAVOR BELOW NORMAL TEMPERATURES ACROSS APPROXIMATELY
THE NORTHERN ONE-THIRD TO ONE-HALF OF THE WESTERN AND CENTRAL CONUS. SHALLOW
ARCTIC AIR USUALLY UNDERCUTS THE MEAN JET, AND OFTEN MOVES SOMEWHAT FARTHER
SOUTH THAN WHAT MODELS MAY INDICATE. THIS ADJUSTMENT WAS SUBJECTIVELY RENDERED
TO THE CONSOLIDATION TOOL, WHICH IS A SKILL-WEIGHTED MEAN OF THE GFS AND ECMWF
ENSEMBLE MEAN REFORECASTS. THEREFORE, BELOW NORMAL TEMPERATURE CHANCES WERE
EXTENDED SOUTHWARD ACROSS WESTERN TEXAS, CONSISTENT WITH WHAT IS COMMONLY
REFERRED TO AS A “BLUE NORTHER”. PROBABILITIES FAVORING BELOW NORMAL MEAN
TEMPERATURES EXCEED 70% FOR PORTIONS OF MONTANA AND NORTH DAKOTA. THIS LARGE
AREA OF FAVORED BELOW NORMAL TEMPERATURES IS ASSOCIATED WITH A MID-LEVEL TROUGH
AND NEAR TO BELOW NORMAL HEIGHTS. AHEAD OF THIS TROUGH, A MID-LEVEL RIDGE AND
ABOVE NORMAL HEIGHTS FAVOR ABOVE NORMAL TEMPERATURES EAST OF AN APPROXIMATE
LINE FROM EASTERN TEXAS TO THE CENTRAL GREAT LAKES REGION. PROBABILITIES
FAVORING ABOVE NORMAL TEMPERATURES EXCEED 60% OVER MUCH OF THE LOWER
MISSISSIPPI VALLEY AND SOUTHEAST, WHERE RETURN FLOW AROUND A SURFACE HIGH IS
EXPECTED TO TRANSPORT INCREASED WARMTH FROM THE ANOMALOUSLY WARM WATERS OF THE
GULF OF MEXICO. THERE IS A SLIGHT TILT IN THE ODDS FOR ANOMALOUSLY WARM
TEMPERATURES OVER CENTRAL SECTIONS OF CALIFORNIA, ASSOCIATED WITH RISING
500-HPA HEIGHTS AND AN APPROACHING RIDGE. SIGNIFICANT UNCERTAINTY REGARDING THE
SPATIAL EXTENT AND DURATION OF ARCTIC AIR LEADS TO NEAR NORMAL TEMPERATURES
BEING FAVORED ACROSS THE SOUTHWEST. IN ALASKA, ABOVE NORMAL TEMPERATURES ARE
FAVORED FOR ALL BUT SOUTHEAST ALASKA, UNDER A STRONG ANOMALOUS RIDGE AND WELL
ABOVE-NORMAL MID-LEVEL HEIGHTS. FOR SOUTHEAST ALASKA, NEAR TO BELOW NORMAL
TEMPERATURES ARE FAVORED IN NORTHEASTERLY ANOMALOUS FLOW EAST OF THE RIDGE
AXIS. MAXIMUM PROBABILITIES FAVORING ABOVE NORMAL TEMPERATURES EXCEED 60% OVER
MUCH OF NORTHERN ALASKA. FOR HAWAII, ABOVE NORMAL TEMPERATURES ARE FAVORED DUE
TO THE PROXIMITY OF ABOVE NORMAL SEA-SURFACE TEMPERATURES (SSTS).
ABOVE NORMAL PRECIPITATION CHANCES ARE ENHANCED FROM THE EASTERN INTERMOUNTAIN
REGION EASTWARD ACROSS THE ROCKIES, GREAT PLAINS, AND THE MISSISSIPPI VALLEY TO
NEAR THE APPALACHIANS. THIS WIDESPREAD AREA OF FAVORED ABOVE NORMAL
PRECIPITATION IS CONSISTENT WITH THE GEFS AND ECMWF ENSEMBLE MEAN REFORECAST
AND RAW PRECIPITATION TOOLS, AND THE PROXIMITY OF AN AMPLIFIED 500-HPA TROUGH
OVER THE WEST-CENTRAL CONUS. PROBABILITIES FAVORING ABOVE NORMAL PRECIPITATION
EXCEED 50% OVER THE SOUTH-CENTRAL CONUS, DUE TO THE MID-LEVEL TROUGH JUST
NOTED, AND ALSO THE POTENTIAL FOR INCREASED PRECIPITATION FROM AN EASTERN
PACIFIC TROPICAL CYCLONE THAT COULD REACH THIS AREA EARLY IN THE 6-10 DAY
PERIOD. AS OF NOON MOUNTAIN DAYLIGHT TIME TODAY, MAJOR HURRICANE NORMA IS WELL
OFF THE SOUTHWESTERN COAST OF MEXICO, AND IS EXPECTED TO PROCEED NORTHWARD OVER
THE NEXT 4-5 DAYS BEFORE GETTING CAUGHT UP AHEAD OF THE WESTERN CONUS TROUGH. A
SEPARATE AREA OF 50% OR BETTER ODDS FOR ABOVE NORMAL PRECIPITATION IS
HIGHLIGHTED OVER THE NORTHERN PLAINS, ASSOCIATED WITH UPSLOPE FLOW NEAR TO
BEHIND THE TROUGH AXIS. BELOW NORMAL PRECIPITATION CHANCES ARE ENHANCED OVER
THE IMMEDIATE ATLANTIC COAST FROM MASSACHUSETTS TO NORTH CAROLINA, RELATED TO
THE DEPARTING MID-LEVEL RIDGE, AND OVER PARTS OF THE PACIFIC NORTHWEST,
ASSOCIATED WITH RISING 500-HPA HEIGHTS AND AN APPROACHING RIDGE. IN ALASKA,
ABOVE NORMAL PRECIPITATION CHANCES ARE ELEVATED FOR NORTHWESTERN ALASKA,
SUPPORTED BY ONSHORE FLOW ASSOCIATED WITH THE NEARBY 500-HPA RIDGE, AND THE RAW
PRECIPITATION PROBABILITIES. BELOW NORMAL PRECIPITATION CHANCES ARE INCREASED
OVER MOST OF CENTRAL AND SOUTHERN ALASKA, WITH CHANCES EXCEEDING 50% OVER
SOUTHEAST ALASKA, IN PROXIMITY TO THE 500-HPA RIDGE AND WELL ABOVE-NORMAL
HEIGHTS. WITH A DEEP ANOMALOUS TROUGH FORECAST TO BE SUFFICIENTLY NORTH OF
HAWAII, CHANCES FOR BELOW NORMAL PRECIPITATION ARE ENHANCED.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 33% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY
8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: NEAR AVERAGE, 3 OUT OF 5, DUE TO
VERY GOOD AGREEMENT AMONG THE MID-LEVEL HEIGHT MODEL FORECASTS, BUT OFFSET BY
SIGNIFICANT DIFFERENCES AMONG THE TEMPERATURE AND PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR OCT 27 - NOV 02, 2023
THE AMPLIFIED 500-HPA FLOW PATTERN ANTICIPATED DURING THE 6-10 DAY PERIOD IS
FORECAST TO SIGNIFICANTLY RELAX DURING WEEK-2, WHILE SHOWING SUBSTANTIAL
EASTWARD MOVEMENT OF THE LONG WAVES. ENERGY ASSOCIATED WITH THE TROUGH NORTH OF
HAWAII IS FORECAST TO PROGRESS EASTWARD AND UNDERCUT THE VERY ANOMALOUS RIDGE
CENTERED OVER SOUTH-CENTRAL ALASKA, WITH THE FLOW BECOMING MORE ZONAL ACROSS
THE CENTRAL AND EASTERN PACIFIC LATER IN WEEK-2. MID-LEVEL HEIGHTS ARE
PREDICTED TO FALL ACROSS NORTHERN ALASKA, AS THE RIDGE IN THIS AREA GRADUALLY
GETS DISPLACED TO THE SOUTH. WEAK RIDGING IS DEPICTED ACROSS THE WESTERN CONUS
ON THE MANUAL HEIGHT BLEND, AND BROAD CYCLONIC CURVATURE/TROUGHING IS INDICATED
MAINLY EAST OF THE ROCKY MOUNTAINS. MID-LEVEL HEIGHTS OVER HAWAII ARE PREDICTED
TO BE NEAR TO SLIGHTLY ABOVE NORMAL, AS THE MEAN TROUGH TO THE NORTH-NORTHEAST
OF THE ISLANDS WEAKENS.
THERE IS A TILT IN THE ODDS TOWARDS WARMER-THAN-NORMAL TEMPERATURES FROM OREGON
AND CALIFORNIA EASTWARD ACROSS THE CENTRAL AND SOUTHERN INTERMOUNTAIN REGION,
AND RIO GRANDE VALLEY, COINCIDENT WITH RISING 500-HPA HEIGHTS AND AN
APPROACHING MID-LEVEL RIDGE. ABOVE NORMAL TEMPERATURE CHANCES ARE ALSO ELEVATED
EAST OF A LINE THAT EXTENDS FROM SOUTHERN TEXAS TO NEW JERSEY, AHEAD OF THE
BROAD TROUGH OVER THE CENTRAL CONUS AND GREAT LAKES REGION. MOST REMAINING
PORTIONS OF THE CONUS ARE FAVORED TO HAVE BELOW NORMAL MEAN TEMPERATURES. THIS
INCLUDES THE NORTHERN TIER STATES FROM WASHINGTON TO THE LOWER GREAT LAKES
REGION, AND EXTENDING SOUTHWARD ACROSS MOST OF THE ROCKIES, THE GREAT PLAINS
DOWN TO NORTHERN TEXAS, APPROXIMATELY THE NORTHWESTERN HALF OF THE MISSISSIPPI
VALLEY, AND THE GREAT LAKES REGION. THIS IS GENERALLY CONSISTENT WITH THE
TEMPERATURE CONSOLIDATION FORECAST. IN ALASKA, A BROAD DE-AMPLIFYING MID-LEVEL
RIDGE AND WELL ABOVE-NORMAL 500-HPA HEIGHTS FAVOR ABOVE NORMAL TEMPERATURES
ACROSS PRACTICALLY THE ENTIRE STATE DURING WEEK-2. ABOVE NORMAL SSTS AROUND
MOST OF THE HAWAIIAN ISLANDS, AND THE PREDICTED WEAKENING OF THE TROUGH TO THE
NORTH-NORTHEAST, FAVOR WARMER-THAN-NORMAL TEMPERATURES ACROSS THE ARCHIPELAGO.
ODDS FAVORING ABOVE NORMAL PRECIPITATION ARE SLIGHTLY ENHANCED FROM
APPROXIMATELY THE NORTHWESTERN QUARTER OF THE CONUS ACROSS COLORADO TO THE
SOUTH-CENTRAL AND SOUTHEASTERN STATES, AND THE OHIO VALLEY. THIS IS ASSOCIATED
WITH A PROGRESSIVE MID-LEVEL TROUGH, AND IS CONSISTENT WITH THE AUTOMATED
PRECIPITATION TOOL. THE RELATIVELY BLAND PRECIPITATION ANOMALY PATTERN ACROSS
THE CONUS IS DUE TO SIGNIFICANT DISCREPANCIES AMONG THE VARIOUS PRECIPITATION
TOOLS, WHICH UNDERSCORES LOW CONFIDENCE. IN ALASKA, BELOW NORMAL PRECIPITATION
CHANCES ARE ELEVATED OVER MOST OF SOUTHERN AND CENTRAL ALASKA, ASSOCIATED WITH
A BROAD MID-LEVEL RIDGE. ONSHORE FLOW ACROSS NORTHWESTERN AND NORTHERN PORTIONS
OF ALASKA TILTS THE ODDS TOWARDS ABOVE NORMAL PRECIPITATION FOR THOSE AREAS.
BELOW NORMAL PRECIPITATION CHANCES ARE FAVORED OVER HAWAII, AS SUPPORTED BY THE
ERF-CON PRECIPITATION TOOL, AND ANTICIPATED WEAKENING OF THE 500-HPA TROUGH AS
IT PASSES NORTHEAST OF HAWAII.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 33% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO
REASONABLE AGREEMENT AMONG THE VARIOUS ENSEMBLE MEAN 500-HPA HEIGHT FORECASTS,
OFFSET BY AN EXPECTED FLATTENING OF THE FLOW PATTERN, AND LARGE DISCREPANCIES
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
NOVEMBER 16.
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:
19581028 - 19541019 - 19881004 - 19531009 - 19511007
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:
19881002 - 19581029 - 19531008 - 19641016 - 19541018
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 25 - 29 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B N OREGON B N NRN CALIF A N
SRN CALIF N N IDAHO B A NEVADA N N
W MONTANA B A E MONTANA B A WYOMING B A
UTAH N A ARIZONA N A COLORADO B A
NEW MEXICO N A N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS B A OKLAHOMA N A
N TEXAS A A S TEXAS A A W TEXAS B A
MINNESOTA B A IOWA B A MISSOURI N A
ARKANSAS A A LOUISIANA A A WISCONSIN B A
ILLINOIS A A MISSISSIPPI A A MICHIGAN A A
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS A B
PENN A N NEW JERSEY A N W VIRGINIA A N
MARYLAND A N DELAWARE A B VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE A A
AK ALEUTIAN A B AK WESTERN A B AK INT BSN A B
AK S INT A B AK SO COAST A B AK PNHDL B B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 27 - NOV 02, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON A A NRN CALIF A A
SRN CALIF A N IDAHO B A NEVADA A N
W MONTANA B N E MONTANA B N WYOMING B N
UTAH A N ARIZONA A N COLORADO B A
NEW MEXICO N N N DAKOTA B N S DAKOTA B N
NEBRASKA B N KANSAS B A OKLAHOMA B A
N TEXAS N A S TEXAS A A W TEXAS B A
MINNESOTA B N IOWA B N MISSOURI B A
ARKANSAS N A LOUISIANA A A WISCONSIN B N
ILLINOIS B N MISSISSIPPI A A MICHIGAN B N
INDIANA B N OHIO N A KENTUCKY N A
TENNESSEE A A ALABAMA A N NEW YORK N N
VERMONT N N NEW HAMP N N MAINE N N
MASS N N CONN N N RHODE IS N N
PENN N N NEW JERSEY A N W VIRGINIA A A
MARYLAND A A DELAWARE A N VIRGINIA A A
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE A A
AK ALEUTIAN A B AK WESTERN A N AK INT BSN A N
AK S INT A B AK SO COAST A B 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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