895
FXUS06 KWBC 201914
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI OCTOBER 20 2023
6-10 DAY OUTLOOK FOR OCT 26 - 30 2023
TODAY’S ENSEMBLE MEAN MODELS ARE IN GOOD AGREEMENT REGARDING THEIR PREDICTION
OF A FAIRLY AMPLIFIED PATTERN OVER THE PACIFIC-NORTH AMERICA REGION DURING THE
6-10 DAY PERIOD. MID-LEVEL TROUGHS ARE FORECAST TO EXTEND SOUTHEASTWARD FROM
THE ALEUTIANS, AND OVER THE WEST-CENTRAL CONTIGUOUS U.S. (CONUS). THE LATTER
FEATURE REPRESENTS A SOUTHWESTWARD EXTENSION OF A BROAD TROUGH OVER EASTERN
CANADA. MID-LEVEL RIDGES ARE DEPICTED OVER THE FAR EASTERN PACIFIC/ALASKA, AND
THE SOUTHEASTERN CONUS. THE MANUAL HEIGHT BLEND DEPICTS THE LARGEST NEGATIVE
500-HPA HEIGHT DEPARTURES (ABOUT -100 METERS) OVER THE CENTRAL PACIFIC, WITH
THE LARGEST POSITIVE 500-HPA HEIGHT DEPARTURES (ABOUT +250 METERS) OVER
SOUTH-CENTRAL AND SOUTHEASTERN MAINLAND 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 FAVORED BELOW NORMAL TEMPERATURES ACROSS THE
WESTERN AND CENTRAL CONUS. THE GEFS REFORECAST-CALIBRATED TEMPERATURE TOOL
FAVORS BELOW NORMAL MEAN TEMPERATURES ACROSS MOST OF THE WESTERN AND CENTRAL
CONUS, WHEREAS THE ECMWF ENSEMBLE MEAN REFORECASTS CONFINE THE FAVORED BELOW
NORMAL TEMPERATURES TO THE NORTH-CENTRAL CONUS. THE CANADIAN REFORECAST TOOL
DEPICTS BELOW NORMAL TEMPERATURES FROM NEAR THE CONTINENTAL DIVIDE EASTWARD
ACROSS THE PLAINS AND NORTHWESTERN HALF OF THE MISSISSIPPI VALLEY. THE
AUTOBLEND TEMPERATURE TOOL DEPICTED A REASONABLE COMPROMISE, WITH NEAR NORMAL
TEMPERATURES FAVORED ACROSS MUCH OF THE SOUTHWEST. SIMILAR TO YESTERDAY’S 6-10
DAY TEMPERATURE OUTLOOK, IT WAS DECIDED TO EXTEND THE FAVORED BELOW NORMAL
TEMPERATURES FAIRLY DEEP INTO WEST TEXAS, CONSISTENT WITH WHAT IS COMMONLY
REFERRED TO AS A “BLUE NORTHER”. PROBABILITIES FAVORING BELOW NORMAL MEAN
TEMPERATURES EXCEED 70% FOR MUCH OF MONTANA AND NORTH DAKOTA. THIS LARGE AREA
OF FAVORED BELOW NORMAL SURFACE TEMPERATURES IS ASSOCIATED WITH A MID-LEVEL
TROUGH AND MOSTLY NEAR NORMAL HEIGHTS. MOST OF THE REMAINDER OF THE CONUS, AND
MOST OF ALASKA, ARE FAVORED TO HAVE ABOVE NORMAL TEMPERATURES. THIS IS
ASSOCIATED WITH MID-LEVEL RIDGING AND ABOVE NORMAL 500-HPA HEIGHTS.
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. MAXIMUM PROBABILITIES FAVORING ABOVE NORMAL TEMPERATURES
EXCEED 60% OVER MUCH OF NORTHERN ALASKA. A RELATIVELY SMALL AREA OF FAVORED
NEAR TO BELOW-NORMAL TEMPERATURES IS INDICATED IN SOUTHEAST ALASKA, RELATED TO
EASTERLY OR NORTHEASTERLY ANOMALOUS FLOW. FOR HAWAII, ABOVE NORMAL TEMPERATURES
ARE FAVORED DUE TO THE PROXIMITY OF ABOVE NORMAL SEA-SURFACE TEMPERATURES
(SSTS) AND OUTPUT FROM THE ERF-CON TOOL.
ABOVE NORMAL PRECIPITATION CHANCES ARE ENHANCED FROM APPROXIMATELY THE
CONTINENTAL DIVIDE EASTWARD TO THE APPALACHIANS, ASSOCIATED WITH WIDESPREAD
MID-LEVEL TROUGHING AND CYCLONIC CURVATURE. THIS WIDESPREAD AREA OF FAVORED
ABOVE NORMAL PRECIPITATION IS CONSISTENT WITH THE VARIOUS ENSEMBLE MEAN
REFORECAST AND RAW PRECIPITATION TOOLS. PROBABILITIES EXCEED 50% OVER MUCH OF
THE SOUTH-CENTRAL CONUS, IN THE MOIST RETURN FLOW AROUND A SURFACE HIGH
ANTICIPATED OVER THE SOUTHEAST. IN ADDITION, PRECIPITATION FROM HURRICANE NORMA
(CURRENTLY SEVERAL HUNDRED MILES SOUTH OF BAJA CALIFORNIA OVER THE EASTERN
PACIFIC) IS PREDICTED TO REACH THE SOUTH-CENTRAL CONUS EARLY IN THE 6-10 DAY
PERIOD. OVER THE WESTERN CONUS, THE GEFS IS SIGNIFICANTLY DRIER AND WARMER THAN
THE OTHER MODELS, AS IT PREDICTS A SOMEWHAT STRONGER RIDGE AND RISING HEIGHTS
ACROSS THIS REGION. BELOW NORMAL PRECIPITATION CHANCES ARE MOST LIKELY ENHANCED
OVER PARTS OF THE PACIFIC NORTHWEST AND NORTHERN INTERMOUNTAIN REGION, WITH
NEAR NORMAL PRECIPITATION BEING FAVORED ACROSS THE CLIMATOLOGICALLY DRIER AREAS
OF THE SOUTHWEST CONUS. THE EARLY STAGES OF ONSHORE FLOW EXPECTED ACROSS THE
CENTRAL PACIFIC COAST FAVOR A SLIGHT TILT IN THE ODDS TOWARDS ABOVE NORMAL
PRECIPITATION. FROM APPROXIMATELY THE APPALACHIANS TO THE EAST COAST, NEAR
NORMAL PRECIPITATION CHANCES ARE FAVORED, ASSOCIATED WITH THE DEPARTING
MID-LEVEL RIDGE AND APPROACHING TROUGH. IN ALASKA, ABOVE NORMAL PRECIPITATION
CHANCES ARE ELEVATED FOR NORTHWESTERN SECTIONS OF THE STATE, 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 THE REMAINDER OF ALASKA, IN PROXIMITY TO THE 500-HPA RIDGE AND
WELL ABOVE-NORMAL HEIGHTS. PROBABILITIES FAVORING BELOW NORMAL PRECIPITATION
EXCEED 50% OVER SOUTHEAST ALASKA. THE HAWAII ERF-CON PRECIPITATION FORECAST
ELEVATES THE ODDS OF BELOW NORMAL PRECIPITATION OVER HAWAII.
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
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 28 - NOV 03, 2023
THE FAIRLY AMPLIFIED 500-HPA FLOW PATTERN ANTICIPATED DURING THE 6-10 DAY
PERIOD IS FORECAST TO SIGNIFICANTLY FLATTEN DURING WEEK-2. A TROUGH IS DEPICTED
ON THE MANUAL HEIGHT BLEND OVER THE VICINITY OF THE ALEUTIANS AND ALASKA
PENINSULA, AND A WEAK RIDGE IS INDICATED FROM SOUTHEAST ALASKA ACROSS THE WEST
COAST OF THE CONUS. BROAD CYCLONIC CURVATURE/TROUGHING IS PREDICTED OVER MOST
OF THE LOWER 48 STATES. MID-LEVEL HEIGHTS OVER HAWAII ARE PREDICTED TO BE NEAR
TO SLIGHTLY ABOVE NORMAL.
THERE IS A TILT IN THE ODDS TOWARDS WARMER-THAN-NORMAL TEMPERATURES FOR MOST
AREAS WEST OF THE CONTINENTAL DIVIDE, CONTINUING EASTWARD ACROSS THE SOUTHERN
PLAINS, LOWER MISSISSIPPI VALLEY, TENNESSEE VALLEY, AND SOUTHEAST DUE TO WEAK
ANOMALOUS RIDGING. MOST REMAINING PORTIONS OF THE CONUS ARE FAVORED TO HAVE
BELOW NORMAL MEAN TEMPERATURES. THIS INCLUDES THE GREAT PLAINS AS FAR SOUTH AS
CENTRAL OKLAHOMA, UPPER AND MIDDLE MISSISSIPPI VALLEY, GREAT LAKES REGION,
NORTHEAST, THE NORTHERN OHIO VALLEY, AND NORTHERN MID-ATLANTIC. THIS IS
CONSISTENT WITH THE TEMPERATURE CONSOLIDATION FORECAST. THE ANOMALOUS RIDGE
OVER ALASKA FAVORS ABOVE NORMAL TEMPERATURES ACROSS PRACTICALLY THE ENTIRE
STATE DURING WEEK-2. ABOVE NORMAL SSTS AROUND MOST OF THE HAWAIIAN ISLANDS
FAVOR WARMER-THAN-NORMAL MEAN TEMPERATURES ACROSS THE ARCHIPELAGO.
ODDS FAVORING ABOVE NORMAL PRECIPITATION ARE SLIGHTLY ENHANCED OVER MUCH OF THE
WESTERN CONUS, ROCKIES, CENTRAL AND SOUTHERN GREAT PLAINS, SOUTHERN HALF OF THE
MISSISSIPPI VALLEY, THE LOWER TENNESSEE VALLEY, AND THE FLORIDA PENINSULA. IN
THE WEST, THIS IS ATTRIBUTED TO INCREASING ONSHORE FLOW FROM THE PACIFIC, WHILE
FOR THE VICINITY OF THE SOUTH-CENTRAL CONUS, IT IS RELATED TO THE BROAD
MID-LEVEL TROUGH AND WIDESPREAD CYCLONIC CURVATURE. THE CONSOLIDATED
PRECIPITATION TOOL ALSO FAVORS ABOVE NORMAL PRECIPITATION FOR THESE SAME
REGIONS. THE EXTENSIVE COVERAGE OF FAVORED NEAR NORMAL PRECIPITATION ACROSS
MUCH OF THE NORTH-CENTRAL AND EASTERN CONUS IS ASSOCIATED WITH A FLATTENING
FLOW PATTERN AT MID-LEVELS, AND THE MOVEMENT OF WEAKER, FASTER SHORT WAVE
TROUGHS MOVING THROUGH THIS REGION. IN ALASKA, ABOVE NORMAL PRECIPITATION
CHANCES ARE ELEVATED OVER THE NORTHERN THIRD OF THE MAINLAND, ASSOCIATED WITH
ONSHORE FLOW AND A MORE ZONAL PATTERN. BELOW NORMAL PRECIPITATION CHANCES ARE
FAVORED FOR THE FAR SOUTHERN MAINLAND, THE ALASKA PENINSULA, AND SOUTHEAST
ALASKA, IN PROXIMITY TO THE MID-LEVEL RIDGE AND HIGHER 500-HPA HEIGHTS. BELOW
NORMAL PRECIPITATION CHANCES ARE FAVORED OVER HAWAII, AS SUPPORTED BY THE
ERF-CON PRECIPITATION TOOL.
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:
19511007 - 19881004 - 20080930 - 19541019 - 19581028
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 - 19801007 - 19511007 - 19641017 - 20080930
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 26 - 30 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B B OREGON B B NRN CALIF A N
SRN CALIF N N IDAHO B N NEVADA N N
W MONTANA B N E MONTANA B A WYOMING B A
UTAH N A ARIZONA N N 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 N A
MINNESOTA B A IOWA B A MISSOURI N A
ARKANSAS A A LOUISIANA A A WISCONSIN B A
ILLINOIS N A MISSISSIPPI A A MICHIGAN N 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 N
PENN A N NEW JERSEY A N W VIRGINIA A A
MARYLAND A N DELAWARE A N 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 N AK INT BSN A B
AK S INT A B AK SO COAST A B AK PNHDL N B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 28 - NOV 03, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A N IDAHO A A NEVADA A A
W MONTANA B A E MONTANA B N WYOMING B A
UTAH A N ARIZONA A N COLORADO A A
NEW MEXICO A A N DAKOTA B N S DAKOTA B N
NEBRASKA B N KANSAS B A OKLAHOMA N A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA B N IOWA B N MISSOURI B N
ARKANSAS N A LOUISIANA A A WISCONSIN B N
ILLINOIS B N MISSISSIPPI A A MICHIGAN B N
INDIANA B N OHIO B N KENTUCKY N N
TENNESSEE A N ALABAMA A N NEW YORK B N
VERMONT B N NEW HAMP B N MAINE B N
MASS B N CONN B N RHODE IS B N
PENN B N NEW JERSEY B N W VIRGINIA N N
MARYLAND N N DELAWARE N N VIRGINIA N 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 N AK INT BSN A N
AK S INT A N AK SO COAST A N 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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