592
FXUS06 KWBC 171902
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 17 2024
6-10 DAY OUTLOOK FOR OCT 23 - 27 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 OVER THE WESTERN ALEUTIAN ISLANDS, WHICH IS SHIFTED
SLIGHTLY WESTWARD RELATIVE TO YESTERDAY’S OUTLOOK. POSITIVE HEIGHT DEPARTURES
EXTEND ACROSS APPROXIMATELY THE SOUTHWESTERN HALF OF ALASKA. A BROAD CYCLONIC
CIRCULATION AND ASSOCIATED NEGATIVE HEIGHT DEPARTURES ARE FORECAST OVER
APPROXIMATELY THE NORTHEASTERN THIRD OF ALASKA AND MOST OF CANADA, WITH A MEAN
TROUGH EXTENDING SOUTHWESTWARD ACROSS BRITISH COLUMBIA AND THE NORTH PACIFIC.
THIS LATTER FEATURE IS ALSO PREDICTED TO BE DISPLACED SOMEWHAT WEST OF
YESTERDAY’S FORECAST LOCATION, WHICH WAS OVER THE NORTHWESTERN CONTIGUOUS U.S.
(CONUS). A ZONAL MEAN RIDGE AND ACCOMPANYING POSITIVE HEIGHT ANOMALIES ARE
PREDICTED ACROSS MOST OF THE CONUS, CONTINUING EASTWARD OVER THE NORTH
ATLANTIC. THE WESTERN PORTION OF THIS ANOMALOUS RIDGE IS NOW DEPICTED ON THE
MANUAL HEIGHT BLEND TO BE OVER PORTIONS OF THE NORTHWESTERN LOWER 48 STATES.
MID-LEVEL HEIGHT ANOMALIES OF AT LEAST 90 METERS ARE PREDICTED ON THE MANUAL
HEIGHT BLEND ACROSS THE CENTRAL PLAINS AND MIDDLE MISSISSIPPI VALLEY. 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 FOR SOUTHEAST ALASKA AND 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 70% OVER A LARGE FRACTION OF THE SOUTHERN CONUS
FROM ARIZONA EASTWARD TO ALABAMA, AND NORTHWARD INTO SOUTHERN KANSAS AND
SOUTHERN MISSOURI. THIS LARGE AREA OF FAVORED ABOVE NORMAL TEMPERATURES IS
SUPPORTED BY PRACTICALLY ALL THE TEMPERATURE TOOLS. IN ALASKA, PREDICTED
WESTERLY FLOW FAVORS NEAR NORMAL TEMPERATURES FOR MOST OF THE STATE. TWO
EXCEPTIONS INCLUDE BELOW NORMAL TEMPERATURES PREDICTED OVER SOUTHEAST ALASKA
(DESCRIBED EARLIER) AND PORTIONS OF THE NORTH SLOPE WHERE ABOVE NORMAL
TEMPERATURES ARE SLIGHTLY FAVORED. ABOVE NORMAL TEMPERATURES ARE LIKELY FOR
HAWAII, CONSISTENT WITH THE TEMPERATURE CONSOLIDATION.
ABOVE NORMAL PRECIPITATION IS SLIGHTLY FAVORED FOR MOST OF WASHINGTON, OREGON,
AND NORTHERN CALIFORNIA, IN ADVANCE OF A 500-HPA TROUGH. THIS IS SUPPORTED BY
THE CONSOLIDATED AND AUTOMATED PRECIPITATION FORECASTS, AND THE
REFORECAST-CALIBRATED PRECIPITATION FORECASTS. ANOMALOUS WETNESS IS ALSO
FAVORED OVER PART OF SOUTHERN TEXAS, AS DEPICTED BY THE AUTOMATED PRECIPITATION
TOOL. ODDS FAVOR BELOW NORMAL PRECIPITATION FROM THE SOUTHWESTERN CONUS INTO
THE NORTH-CENTRAL STATES, AND OVER APPROXIMATELY THE EASTERN QUARTER OF THE
CONUS, DUE TO WIDESPREAD ZONAL RIDGING AND POSITIVE HEIGHT ANOMALIES. THE
FAVORED NEAR NORMAL PRECIPITATION BAND THAT EXTENDS FROM THE GREAT LAKES
SOUTHWESTWARD INTO TEXAS IS RELATED TO THE PASSAGE OF A FRONT AND THE EXPECTED
INFLUX OF GULF MOISTURE. MOST OF ALASKA IS FAVORED TO HAVE ABOVE NORMAL
PRECIPITATION WITH SHORTWAVE TROUGHS MOVING OVER THE TOP OF THE PREDICTED
ALEUTIAN RIDGE. ABOVE NORMAL PRECIPITATION IS 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 25 - 31 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 A BIT EAST COMPARED TO ITS EXPECTED LOCATION DURING THE EARLIER 6-10
DAY PERIOD. WHILE THE GEFS AND ECENS FORECAST A SIGNIFICANT REDUCTION IN THE
MAGNITUDE OF THE POSITIVE HEIGHT DEPARTURES ASSOCIATED WITH THIS RIDGE, THE
CMCE DEPICTS VERY LITTLE WEAKENING DURING WEEK-2. THE MID-LEVEL TROUGH OVER
BRITISH COLUMBIA AND THE NORTH PACIFIC IS EXPECTED TO SHIFT EASTWARD TOWARDS
THE PACIFIC NORTHWEST, INDICATING THE FORECASTED UPSTREAM RETROGRESSION OF
LONG-WAVE FEATURES MAY BE SHORT-LIVED. FARTHER NORTH, THE MANUAL HEIGHT BLEND
DEPICTS NEAR TO SLIGHTLY BELOW NORMAL HEIGHTS OVER MOST OF MAINLAND ALASKA. FOR
THE CONUS, THE PRIMARY CIRCULATION FEATURE IS A ZONAL MEAN RIDGE, THOUGH WITH
SIGNIFICANTLY REDUCED POSITIVE HEIGHT ANOMALIES. 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. BELOW NORMAL
TEMPERATURE CHANCES ARE ELEVATED OVER THE PACIFIC NORTHWEST, 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 NEAR NORMAL
TEMPERATURES OVER MOST OF THE STATE, WITH ABOVE (BELOW) NORMAL TEMPERATURES
ACROSS THE NORTHEAST (SOUTHEAST). 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. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FOR MUCH OF THE
WESTERN CONUS, DUE TO SUFFICIENT MOISTURE STREAMING NORTHEASTWARD FROM THE
NORTH PACIFIC IN ADVANCE OF A 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. BELOW NORMAL
PRECIPITATION IS FAVORED FROM THE FOUR CORNERS STATES AND WEST TEXAS NORTHWARD
INTO THE DAKOTAS, AND (SLIGHTLY) FAVORED OVER THE NORTHEAST AND UPPER
MID-ATLANTIC. 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, OFFSET BY
VARIABILITY OF THE PREDICTED FORECAST PATTERN AND WEAKENING HEIGHT ANOMALIES
DURING THIS PERIOD.
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:
19881013 - 20051027 - 19631001 - 19970930 - 19511011
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:
19881011 - 20051027 - 19570929 - 19901029 - 19511010
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 23 - 27 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON A A NRN CALIF A A
SRN CALIF A N IDAHO A N NEVADA A N
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 N
N TEXAS A N S TEXAS A N W TEXAS A B
MINNESOTA A N IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA A N WISCONSIN A N
ILLINOIS A N MISSISSIPPI A N MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
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 B GEORGIA A B
FL PNHDL A N FL PENIN A N AK N SLOPE N A
AK ALEUTIAN N N AK WESTERN N A AK INT BSN N A
AK S INT N A AK SO COAST B A AK PNHDL B N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 25 - 31 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON N A NRN CALIF A A
SRN CALIF A N IDAHO N A NEVADA A A
W MONTANA N A E MONTANA A N WYOMING A N
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A N S DAKOTA A N
NEBRASKA A N KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS A N W TEXAS A B
MINNESOTA A N IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA A N WISCONSIN A N
ILLINOIS A N MISSISSIPPI A N MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A N 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 N
MARYLAND A B DELAWARE A B VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A A AK N SLOPE N A
AK ALEUTIAN N A AK WESTERN N A AK INT BSN N A
AK S INT N 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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