629
FXUS06 KWBC 181902
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 18 2024
6-10 DAY OUTLOOK FOR OCT 24 - 28 2024
THERE IS VERY GOOD AGREEMENT AMONG THE 0Z ECENS, 0Z CMCE, AND THE 6Z GEFS
500-HPA HEIGHT FORECASTS ON THE PREDICTED CIRCULATION PATTERN ACROSS NORTH
AMERICA DURING THE 6-10 DAY PERIOD. DYNAMICAL MODELS PREDICT A HIGHLY ANOMALOUS
ZONAL RIDGE CENTERED NEAR THE ALEUTIAN ISLANDS. THE MANUAL HEIGHT BLEND DEPICTS
POSITIVE HEIGHT DEPARTURES THAT EXTEND ACROSS THE ALASKA PENINSULA AND FAR
SOUTHWESTERN PART OF THE MAINLAND. A BROAD CYCLONIC CIRCULATION AND ASSOCIATED
NEGATIVE HEIGHT DEPARTURES ARE FORECAST OVER MOST OF MAINLAND ALASKA AND
CANADA, AND OVER THE PACIFIC NORTHWEST. THIS IS CONSISTENT WITH A SLIGHT
SOUTHWARD SHIFT OF THE MEAN STORM TRACK ACROSS SOUTHERN ALASKA AND THE ADJACENT
NORTHERN GULF OF ALASKA. A ZONAL MEAN RIDGE AND ACCOMPANYING POSITIVE HEIGHT
ANOMALIES ARE PREDICTED ACROSS MOST OF THE CONTIGUOUS U.S. (CONUS), WITH
MID-LEVEL HEIGHTS FORECAST TO RISE OVER THE SOUTHWESTERN CONUS. MID-LEVEL
HEIGHT ANOMALIES OF AT LEAST 90 METERS ARE PREDICTED ON THE MANUAL HEIGHT BLEND
OVER THE UPPER GREAT LAKES, OHIO VALLEY, MID-UPPER MISSISSIPPI VALLEY AND
ADJACENT PARTS OF THE EASTERN PLAINS, AND ALSO IN THE VICINITY OF ARIZONA. THIS
BROAD-SCALE CIRCULATION PATTERN IS CONSISTENT WITH A POSITIVE ARCTIC
OSCILLATION, WHICH TYPICALLY FEATURES POSITIVE 500-HPA HEIGHT ANOMALIES
PREDICTED ACROSS THE MIDDLE LATITUDES (INCLUDING THE CONUS), AND NEGATIVE
500-HPA HEIGHT ANOMALIES OVER THE ARCTIC. FOR HAWAII, 500-HPA HEIGHT ANOMALIES
ARE FORECAST TO BE NEAR OR SLIGHTLY ABOVE AVERAGE.
BELOW NORMAL TEMPERATURES ARE FAVORED FROM MUCH OF ALASKA SOUTHEASTWARD INTO
THE PACIFIC NORTHWEST, DUE TO ANOMALOUS NORTHWEST FLOW AND/OR THE PROXIMITY OF
A PREDICTED MID-LEVEL TROUGH. ABOVE NORMAL TEMPERATURES ARE FAVORED ACROSS MOST
OF THE REMAINDER OF THE CONUS, UNDER PREDICTED POSITIVE 500-HPA HEIGHT
ANOMALIES AND MID-LEVEL RIDGING. ODDS SURPASS 80% OVER MUCH OF THE CENTRAL
CONUS. THIS LARGE AREA OF FAVORED ABOVE NORMAL TEMPERATURES IS SUPPORTED BY
PRACTICALLY ALL THE TEMPERATURE TOOLS. ABOVE NORMAL TEMPERATURES ARE LIKELY FOR
HAWAII, CONSISTENT WITH THE 6-10 DAY TEMPERATURE CONSOLIDATION.
ABOVE NORMAL PRECIPITATION IS FAVORED FROM THE NORTHERN ROCKIES SOUTHWESTWARD
ACROSS NORTHERN CALIFORNIA, IN ADVANCE OF AN UPPER-LEVEL TROUGH. THIS IS
SUPPORTED BY THE CONSOLIDATED AND AUTOMATED PRECIPITATION FORECASTS, AND THE
REFORECAST-CALIBRATED PRECIPITATION FORECASTS. ODDS FAVOR BELOW NORMAL
PRECIPITATION FOR MOST OF THE REMAINDER OF THE CONUS, DUE TO WIDESPREAD ZONAL
RIDGING AND POSITIVE HEIGHT ANOMALIES. THE WEAKNESS IN PROBABILITIES FOR BELOW
NORMAL PRECIPITATION THAT EXTENDS FROM THE GREAT LAKES SOUTHWESTWARD INTO THE
SOUTHERN PLAINS IS RELATED TO FRONTAL ACTIVITY AND AN EXPECTED INCREASE IN
ATLANTIC AND GULF MOISTURE. IN ALASKA, ABOVE NORMAL PRECIPITATION IS FAVORED
FOR MOST OF THE STATE NORTH OF A ZONAL RIDGE AXIS, SUPPORTED BY PRACTICALLY ALL
PRECIPITATION TOOLS. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FOR THE
HAWAIIAN ISLANDS AS INDICATED BY THE CONSOLIDATED AND AUTOMATED PRECIPITATION
TOOLS.
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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
VERY GOOD AGREEMENT AMONG THE DYNAMICAL MODEL HEIGHT FORECASTS, AND THE
TEMPERATURE TOOLS, OFFSET BY INCREASED DIFFERENCES AMONG THE PRECIPITATION
TOOLS.
8-14 DAY OUTLOOK FOR OCT 26 - NOV 01, 2024
DYNAMICAL MODEL FORECASTS FROM THE ECENS, GEFS AND CMCE ENSEMBLE MEANS ARE IN
REASONABLE AGREEMENT ON THE AVERAGE LARGE-SCALE 500-HPA HEIGHT PATTERN DURING
THE WEEK-2 PERIOD, DESPITE WEAKENING ANOMALIES AND SOME VARIATIONS ON THE 6-10
DAY CIRCULATION THEME. THE STRONG ANOMALOUS RIDGE PREDICTED NEAR THE ALEUTIANS
IS SHIFTED SOUTHWARD COMPARED TO ITS EXPECTED LOCATION DURING THE EARLIER 6-10
DAY PERIOD, AND THE DYNAMICAL MODELS FORECAST A SIGNIFICANT REDUCTION IN THE
MAGNITUDE OF THE POSITIVE HEIGHT DEPARTURES ASSOCIATED WITH THIS RIDGE DURING
WEEK-2. THE MANUAL HEIGHT BLEND DEPICTS BELOW NORMAL 500-HPA HEIGHTS OVER
MAINLAND ALASKA, WITH NEAR TO SLIGHTLY BELOW NORMAL HEIGHTS EXTENDING SOUTHWARD
ACROSS THE ALASKA PANHANDLE AND INTO THE WESTERN CONUS. A ZONAL MEAN RIDGE IS
DEPICTED MOSTLY OVER THE CENTRAL AND EASTERN CONUS, WITH PREDICTED HEIGHT
ANOMALIES IN EXCESS OF 60 METERS OVER MUCH OF THE NORTHEASTERN QUARTER OF THE
LOWER 48 STATES. AS WAS THE CASE WITH THE EARLIER 6-10 DAY PERIOD, NEAR TO
SLIGHTLY ABOVE NORMAL 500-HPA HEIGHTS ARE ANTICIPATED ACROSS THE HAWAIIAN
ISLANDS.
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE CONUS ASSOCIATED WITH A
ZONAL MEAN RIDGE AND POSITIVE HEIGHT ANOMALIES. THIS IS SUPPORTED BY
REFORECAST-CALIBRATED, BIAS-CORRECTED, AND RAW TEMPERATURE TOOLS. CHANCES
EXCEED 70% OVER MOST OF THE EASTERN HALF OF THE CONUS, FROM THE GREAT PLAINS TO
THE APPALACHIANS. CHANCES FOR BELOW NORMAL TEMPERATURE ARE ELEVATED OVER
WASHINGTON, OREGON, AND PARTS OF NEIGHBORING STATES, ASSOCIATED WITH A WEAK
MID-LEVEL TROUGH. THE ALASKA TEMPERATURE OUTLOOK FOR WEEK-2 IS VERY SIMILAR TO
THAT OF THE EARLIER 6-10 DAY PERIOD, FEATURING BELOW NORMAL TEMPERATURES OVER
MOST OF THE STATE, WITH A SMALL SLIVER OF ABOVE NORMAL TEMPERATURES FAVORED FOR
THE NORTH SLOPE. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR HAWAII IN WEEK-2,
CONSISTENT WITH THE TEMPERATURE CONSOLIDATION.
ABOVE NORMAL PRECIPITATION IS FAVORED ACROSS MOST OF ALASKA, UNDER ZONAL
MID-LEVEL FLOW. WETTER-THAN-NORMAL CONDITIONS ARE ALSO FAVORED FOR MOST OF THE
NORTHWESTERN QUARTER OF THE CONUS, EXTENDING SOUTHWARD INTO CENTRAL CALIFORNIA.
THIS IS ASSOCIATED WITH A WEAK MEAN TROUGH. EASTERLY FLOW SOUTH OF SURFACE HIGH
PRESSURE CENTERED OVER THE MID-ATLANTIC TILTS THE ODDS SLIGHTLY TOWARDS
WETTER-THAN-NORMAL CONDITIONS FOR THE FLORIDA PENINSULA. FROM THE UPPER GREAT
LAKES REGION SOUTHWESTWARD TO OKLAHOMA AND ARKANSAS, ABOVE NORMAL PRECIPITATION
IS FAVORED, AND IS WELL SUPPORTED BY THE REFORECAST-CALIBRATED AND RAW
PRECIPITATION TOOLS. BELOW NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR THE
SOUTHERN FOUR CORNERS REGION AND WEST TEXAS, AND FOR MUCH OF THE EASTERN
QUARTER OF THE CONUS. THIS IS CONSISTENT WITH THE CONSOLIDATED AND AUTOMATED
PRECIPITATION GUIDANCE. FOR THE HAWAIIAN ISLANDS, THE CONSOLIDATION TOOL FAVORS
INCREASED ODDS OF ABOVE NORMAL PRECIPITATION.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 35% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 25% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO
GOOD OVERALL AGREEMENT AMONG THE DYNAMICAL MODEL HEIGHT FORECASTS ON A FAST
ZONAL PATTERN, GOOD AGREEMENT AMONG THE TEMPERATURE TOOLS, BUT OFFSET BY
SIGNIFICANT UNCERTAINTY IN THE PRECIPITATION 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
NOVEMBER 21.
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:
20051028 - 19571001 - 19511011 - 19631002 - 19881014
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:
19570930 - 19901030 - 19511012 - 19971004 - 19530929
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 24 - 28 2024
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 B
W MONTANA A N E MONTANA A B WYOMING A B
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA A B WISCONSIN A B
ILLINOIS A B MISSISSIPPI A B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A B NEW YORK A B
VERMONT N B NEW HAMP N B MAINE N B
MASS N B CONN N B RHODE IS N B
PENN A B NEW JERSEY A B W VIRGINIA A B
MARYLAND A B DELAWARE A B VIRGINIA A B
N CAROLINA A B S CAROLINA A B GEORGIA A B
FL PNHDL A B FL PENIN A N AK N SLOPE B A
AK ALEUTIAN N A AK WESTERN N A AK INT BSN B A
AK S INT B A AK SO COAST B A AK PNHDL B N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 26 - NOV 01, 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF N A
SRN CALIF N N IDAHO N A NEVADA N N
W MONTANA N A E MONTANA A A WYOMING A A
UTAH A N ARIZONA A N COLORADO A N
NEW MEXICO A N N DAKOTA A N S DAKOTA A N
NEBRASKA A N KANSAS A A OKLAHOMA A A
N TEXAS A N S TEXAS A N W TEXAS A N
MINNESOTA A N IOWA A A MISSOURI A A
ARKANSAS A N LOUISIANA A N WISCONSIN A A
ILLINOIS A A MISSISSIPPI A N MICHIGAN A A
INDIANA A N 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 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 A B S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A A AK N SLOPE B A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST B A AK PNHDL B 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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