920
FXUS06 KWBC 181903
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED OCTOBER 18 2023
6-10 DAY OUTLOOK FOR OCT 24 - 28 2023
TODAY’S ENSEMBLE MEAN MODELS ARE IN EXCELLENT 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 NEAR 160W), THE WEST-CENTRAL CONTIGUOUS U.S. (CONUS), AND THE
WESTERN ATLANTIC. MID-LEVEL RIDGES ARE DEPICTED OVER THE EASTERN
PACIFIC/ALASKA, AND THE EASTERN CONUS. THE MANUAL HEIGHT BLEND DEPICTS THE
LARGEST NEGATIVE 500-HPA HEIGHT DEPARTURES (-100 METERS) ARE PREDICTED OVER THE
CENTRAL PACIFIC, WITH THE LARGEST POSITIVE 500-HPA HEIGHT DEPARTURES (+250
METERS) OVER ALASKA’S KENAI PENINSULA. MID-LEVEL HEIGHTS ARE EXPECTED TO BE
SLIGHTLY ABOVE NORMAL OVER HAWAII.
THE SURFACE TEMPERATURE PATTERN PREDICTED FOR THE UPCOMING 6-10 DAY PERIOD IS
CONSISTENT WITH THE FORECASTED LONGWAVE FEATURES OF THE 500-HPA CIRCULATION
PATTERN. BELOW NORMAL MEAN TEMPERATURES ARE FAVORED FOR MUCH OF THE CONUS WEST
OF THE CONTINENTAL DIVIDE, AND FOR MUCH OF THE NORTHERN AND CENTRAL GREAT
PLAINS, AND WESTERN MINNESOTA, EAST OF THE DIVIDE, UNDER A MID-LEVEL TROUGH AND
BELOW NORMAL 500-HPA HEIGHTS. PROBABILITIES FAVORING BELOW NORMAL MEAN
TEMPERATURES EXCEED 70% FOR PARTS OF MONTANA. ABOVE NORMAL TEMPERATURES ARE
FAVORED AHEAD OF THIS TROUGH UNDER ABOVE NORMAL 500-HPA HEIGHTS, FROM MOST OF
THE SOUTHERN PLAINS, EASTERN PORTIONS OF THE CENTRAL PLAINS, AND MOST OF THE
MISSISSIPPI VALLEY EASTWARD TO THE ATLANTIC COAST. PROBABILITIES FAVORING ABOVE
NORMAL EXCEED 60% OVER THE VICINITY OF THE LOWER MISSISSIPPI VALLEY AND EASTERN
TEXAS, WHERE RETURN FLOW AROUND A SURFACE HIGH IS EXPECTED TO TRANSPORT
INCREASED WARMTH FROM THE ANOMALOUSLY WARM WATERS OF THE GULF OF MEXICO. 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 NORTHERLY
AND EASTERLY ANOMALOUS FLOW NEAR THE RIDGE AXIS. MAXIMUM PROBABILITIES FAVORING
ABOVE NORMAL TEMPERATURES EXCEED 60% OVER PORTIONS OF WESTERN AND 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 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 CALIBRATED-REFORECAST 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 CENTRAL
CONUS, WITH 60% OR GREATER ODDS FAVORED FOR THE SOUTHERN HIGH PLAINS, 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 9AM MOUNTAIN DAYLIGHT TIME TODAY,
HIGH-END TROPICAL STORM NORMA IS WELL OFF THE SOUTHWESTERN COAST OF MEXICO, AND
IS EXPECTED TO PROCEED NORTHWARD OVER THE NEXT FIVE DAYS BEFORE GETTING CAUGHT
UP AHEAD OF THE WESTERN CONUS TROUGH. BELOW NORMAL PRECIPITATION CHANCES ARE
ENHANCED OVER NORTHERN CALIFORNIA (IN RISING 500-HPA HEIGHTS BEHIND THE MEAN
MID-LEVEL TROUGH), AND NEAR THE EAST COAST, IN PROXIMITY TO AN AMPLIFIED
MID-LEVEL RIDGE AND SURFACE ANTICYCLONE. IN ALASKA, ABOVE NORMAL PRECIPITATION
CHANCES ARE ELEVATED FOR THE ALASKA PENINSULA, KODIAK ISLAND, AND MOST OF
WESTERN AND NORTHERN ALASKA, SUPPORTED BY ONSHORE FLOW ASSOCIATED WITH THE
NEARBY 500-HPA RIDGE, AND THE CALIBRATED-REFORECAST PRECIPITATION TOOLS. BELOW
NORMAL PRECIPITATION CHANCES ARE INCREASED OVER THE WESTERN ALEUTIANS (BEHIND A
TROUGH AXIS) AND SOUTHEAST ALASKA (EAST OF A RIDGE AXIS). WITH A DEEP ANOMALOUS
TROUGH FORECAST NORTH OF HAWAII, THE NORTHERN AND CENTRAL ISLANDS (KAUAI
THROUGH KAHOOLAWE AND MOST OF MAUI) ARE FAVORED TO RECEIVE NEAR TO ABOVE NORMAL
PRECIPITATION, WHILE PRIMARILY BELOW NORMAL PRECIPITATION IS FAVORED ACROSS
NIIHAU AND THE BIG ISLAND, BOTH LOCATIONS BEING MORE DISTANT FROM THE MID-LEVEL
TROUGH.
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: WELL ABOVE AVERAGE, 5 OUT OF 5,
DUE TO VERY GOOD AGREEMENT AMONG THE MID-LEVEL HEIGHT AND SURFACE
TEMPERATURE/PRECIPITATION FORECASTS.
8-14 DAY OUTLOOK FOR OCT 26 - NOV 01, 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. SHORTER-WAVELENGTH ENERGY EJECTING
NORTHEASTWARD FROM THE WESTERN CONUS TROUGH, COMBINED WITH THE SLIGHT SOUTHWARD
MOTION OF A BROAD TROUGH OVER EASTERN CANADA, HELP TO DIMINISH THE AMPLITUDE OF
THE EASTERN CONUS RIDGE. MID-LEVEL HEIGHTS ARE ALSO PREDICTED TO FALL ACROSS
NORTHERN ALASKA, AS THE RIDGE IN THIS AREA GRADUALLY GETS DISPLACED TO THE
SOUTH. MID-LEVEL HEIGHTS OVER HAWAII ARE PREDICTED TO BE CLOSE TO NORMAL, AS
THE MEAN TROUGH TO THE NORTH OF THE ISLANDS WEAKENS.
THERE IS A TILT IN THE ODDS TOWARDS WARMER-THAN-NORMAL TEMPERATURES OVER
PORTIONS OF THE WEST COAST STATES, COINCIDENT WITH RISING 500-HPA HEIGHTS AND
AN APPROACHING MID-LEVEL RIDGE. BELOW NORMAL MEAN TEMPERATURES ARE FAVORED FOR
PORTIONS OF THE INTERMOUNTAIN REGION, THE ROCKIES, MOST OF THE GREAT PLAINS,
THE MISSISSIPPI VALLEY FROM MINNESOTA TO WESTERN ARKANSAS, AND THE UPPER GREAT
LAKES REGION. THIS IS GENERALLY CONSISTENT WITH THE TEMPERATURE CONSOLIDATION
FORECAST, STATISTICAL TEMPERATURE ANALOGS FROM THE MANUAL HEIGHT BLEND, AND THE
PROXIMITY OF A MID-LEVEL TROUGH AND 500-HPA HEIGHTS THAT ARE WITHIN ABOUT 40
METERS OF NORMAL. ODDS FOR BELOW NORMAL TEMPERATURES EXCEED 60% OVER PARTS OF
THE NORTHERN HIGH PLAINS. ABOVE NORMAL TEMPERATURES ARE FAVORED AHEAD OF THE
TROUGH JUST NOTED, OVER THE ATLANTIC AND GULF COAST STATES. 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, FAVOR WARMER-THAN-NORMAL TEMPERATURES ACROSS THE
ARCHIPELAGO.
ABOVE NORMAL PRECIPITATION CHANCES ARE ENHANCED FROM ABOUT THE ROCKIES EASTWARD
ACROSS THE MISSISSIPPI VALLEY TO THE APPALACHIANS AND THE SOUTHEAST. THIS IS
ASSOCIATED WITH A PROGRESSIVE, MID-LEVEL TROUGH, AND IS CONSISTENT WITH THE
PRECIPITATION CONSOLIDATION TOOL. MAXIMUM PROBABILITIES FOR ABOVE NORMAL
PRECIPITATION EXCEED 40% OVER SOUTHERN SECTIONS OF THE PLAINS AND MISSISSIPPI
VALLEY, IN MOIST SOUTHWESTERLY RETURN FLOW NEAR THE SURFACE. NEAR TO BELOW
NORMAL PRECIPITATION IS FAVORED FROM ABOUT THE ROCKIES WESTWARD TO THE PACIFIC
COAST, AS 500-HPA HEIGHTS RISE IN RESPONSE TO AN APPROACHING RIDGE. THIS IS
ALSO SUPPORTED BY THE STATISTICAL PRECIPITATION ANALOG TOOL BASED ON THE MANUAL
HEIGHT FORECAST, AND THE CONSOLIDATED PRECIPITATION TOOL. BOTH OF THESE TOOLS
ALSO DEPICT SLIGHTLY ELEVATED ODDS OF BELOW NORMAL PRECIPITATION FOR PORTIONS
OF NEW ENGLAND, ASSOCIATED WITH THE RAPIDLY WEAKENING EAST COAST RIDGE. IN
ALASKA, BELOW NORMAL PRECIPITATION CHANCES ARE ELEVATED OVER THE ALEUTIANS
(BEHIND A TROUGH AXIS), AND SOUTHERN PORTIONS OF SOUTHEAST ALASKA (WITH A RIDGE
AXIS OVERHEAD). ONSHORE FLOW OVER WESTERN AND NORTHERN PORTIONS OF ALASKA TILTS
THE ODDS TOWARDS ABOVE NORMAL PRECIPITATION FOR MOST REMAINING PORTIONS OF THE
STATE. BELOW NORMAL PRECIPITATION CHANCES ARE FAVORED OVER HAWAII, AS SUPPORTED
BY THE ERF-CON PRECIPITATION TOOL, AND ANTICIPATED WEAKENING OF THE NEARBY
TROUGH TO THE NORTH 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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG THE VARIOUS ENSEMBLE MEAN 500-HPA HEIGHT FORECASTS, OFFSET
BY AN EXPECTED DE-AMPLIFICATION OF THE FLOW PATTERN.
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
OCTOBER 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:
19581027 - 19541019 - 19531008 - 20051028 - 20081004
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:
19581029 - 19541018 - 20081003 - 19531008 - 20051027
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 24 - 28 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF N B
SRN CALIF N N IDAHO B A NEVADA B N
W MONTANA B A E MONTANA B A WYOMING B A
UTAH B A ARIZONA B A COLORADO B A
NEW MEXICO N A N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA N A IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN A 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 B NEW HAMP A B MAINE A B
MASS A B CONN A B RHODE IS A B
PENN A N NEW JERSEY A B W VIRGINIA A N
MARYLAND A B DELAWARE A B VIRGINIA A B
N CAROLINA A B S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE A A
AK ALEUTIAN A N AK WESTERN A A AK INT BSN A A
AK S INT A N AK SO COAST A B AK PNHDL B B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 26 - NOV 01, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N N OREGON A B NRN CALIF A B
SRN CALIF A N IDAHO B B NEVADA N B
W MONTANA B N E MONTANA B A WYOMING B A
UTAH B N 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 B A
N TEXAS N A S TEXAS A A W TEXAS N A
MINNESOTA B A IOWA B A MISSOURI B A
ARKANSAS B A LOUISIANA A A WISCONSIN B A
ILLINOIS B A MISSISSIPPI A A MICHIGAN B A
INDIANA N A OHIO N A KENTUCKY N A
TENNESSEE N A ALABAMA A A NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS A B CONN A N RHODE IS A B
PENN A N NEW JERSEY A N W VIRGINIA N A
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A N S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN A N AK WESTERN A A AK INT BSN A A
AK S INT A A AK SO COAST A A 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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