865
FXUS06 KWBC 102001
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST TUE DECEMBER 10 2024
6-10 DAY OUTLOOK FOR DEC 16 - 20 2024
POSITIVE MID-LEVEL HEIGHT ANOMALIES ARE GENERALLY FAVORED ACROSS THE CONTIGUOUS
UNITED STATES (CONUS) DURING THE 6-10 DAY PERIOD. THE STRONGEST ANOMALIES
DURING THE PERIOD ARE FORECAST FOR THE WESTERN CONUS WITH A STRONG MID-LEVEL
RIDGE. THE AXIS OF THIS RIDGE IS FORECAST TO BE JUST INLAND BRINGING ONSHORE
MID-LEVEL FLOW TO THE WEST COAST OF NORTH AMERICA. IN THE EAST, HEIGHT
ANOMALIES ARE REDUCED IN MAGNITUDE RELATIVE TO YESTERDAY’S FORECAST. THIS LEADS
TO A WEAK TROUGH BEGINNING TO DEVELOP ACROSS THE REGION. AN AREA OF STRONGLY
BELOW-NORMAL MID-LEVEL HEIGHTS IS FORECAST ACROSS THE NORTH PACIFIC LEADING TO
ONSHORE, SOUTHERLY FLOW INTO MUCH OF ALASKA. POSITIVE 500-HPA HEIGHTS ARE
FORECAST FOR HAWAII.
ABOVE-NORMAL TEMPERATURES ARE FAVORED ACROSS MOST OF THE COUNTRY TODAY. THE
STRONGEST CHANCES ARE IN HAWAII WHERE ABOVE-NORMAL CHANCES EXCEED 80% WITH
STRONG AGREEMENT AMONG REFORECAST AND SHORT-TERM BIAS-CORRECTED TOOLS BENEATH
POSITIVE MID-LEVEL HEIGHT ANOMALIES. IN THE CONUS, POSITIVE MID-LEVEL HEIGHT
ANOMALIES FORECAST RESULT IN ABOVE-NORMAL TEMPERATURES TO BE FAVORED
COAST-TO-COAST WITH THE EXCEPTION OF PARTS OF SOUTHERN FLORIDA AND THE UPPER
MISSISSIPPI VALLEY. THE STRONGEST CHANCES FOR ABOVE-NORMAL TEMPERATURES (>60%)
ARE ACROSS THE NORTHEAST NEAREST THE MID-LEVEL 500-HPA HEIGHT ANOMALY CENTER,
AND IN THE SOUTHWEST BENEATH MID-LEVEL RIDGING. IN ALASKA, SOUTHERLY FLOW
BRINGS ABOVE-NORMAL TEMPERATURE CHANCES TO MOST OF ALASKA.
ABOVE-NORMAL PRECIPITATION IS FORECAST FOR SOUTHERN ALASKA THROUGH THE PACIFIC
NORTHWEST INTO NORTHERN CALIFORNIA. A STRONG TROUGH OVER THE NORTHERN PACIFIC
OCEAN AND RIDGE ACROSS WESTERN NORTH AMERICA ARE LIKELY TO BRING ONSHORE
MID-LEVEL FLOW INTO THE WEST COAST OF NORTH AMERICA. THERE REMAINS SOME
UNCERTAINTY IN REGARDS TO THE MID-LEVEL RIDGE AXIS IN THE WESTERN CONUS.
FURTHER INLAND, WOULD LIKELY RESULT IN MORE PRECIPITATION FOR THE NORTHWEST AND
NORTHERN CALIFORNIA RELATIVE TO THE AXIS REMAINING NEAR THE IMMEDIATE WEST
COAST. ACROSS THE SOUTHWEST AND INTERIOR WEST, BELOW-NORMAL PRECIPITATION IS
FORECAST WITH LITTLE OF THE MOISTURE LIKELY TO REACH THESE AREAS. IN THE EAST,
THE PRECIPITATION FORECAST IS QUITE UNCERTAIN. THE GEFS MAINTAINS A WETTER
PATTERN FOR PORTIONS OF THE SOUTHERN PLAINS THROUGH THE MIDDLE MISSISSIPPI
VALLEY ASSOCIATED WITH A CLIPPER SYSTEM EARLY IN THE PERIOD. TOOLS CONTINUE TO
SHOW ADDITIONAL ABOVE-NORMAL PRECIPITATION CHANCES FOR PORTIONS OF NEW ENGLAND
AND BELOW-NORMAL FOR PORTIONS OF THE SOUTHEAST. IN NORTHERN ALASKA,
BELOW-NORMAL PRECIPITATION IS FAVORED WITH MOST MOISTURE REMAINING IN SOUTHERN
ALASKA. BENEATH A MID-LEVEL RIDGE, HAWAII IS FAVORED TO HAVE BELOW-NORMAL
PRECIPITATION.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 25% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED
ON DAY 8, 35% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, AND 30%
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. GOOD
AGREEMENT AMONG THE DYNAMICAL AND STATISTICAL TOOLS IS OFFSET BY A PROGRESSIVE
AND SHIFTING PATTERN AND WEAK PRECIPITATION SIGNALS.
8-14 DAY OUTLOOK FOR DEC 18 - 24 2024
MID-LEVEL RIDGING REMAINS FORECAST ACROSS MUCH OF THE WESTERN CONUS. THE
MID-LEVEL RIDGE AXIS IS FORECAST TO BE JUST INLAND BRINGING ONSHORE
SOUTHWESTERLY FLOW ACROSS THE PACIFIC NORTHWEST INTO NORTHERN CALIFORNIA.
ACROSS THE EASTERN CONUS, ABOVE-NORMAL HEIGHTS REMAIN FORECAST BUT REDUCED IN
MAGNITUDE RELATIVE TO THE 6-10 DAY PERIOD AS THE PATTERN PROGRESSES EAST.
NEAR-NORMAL MID-LEVEL HEIGHTS ARE FORECAST ACROSS PORTIONS OF FLORIDA AND THE
SURROUNDING AREA. IN ALASKA AND THE NORTH PACIFIC A DEEP TROUGH IS FORECAST.
THIS TROUGH IS FURTHER EAST RELATIVE TO THE 6-10 DAY PERIOD. POSITIVE HEIGHT
ANOMALIES REMAIN FORECAST FOR HAWAII.
ABOVE-NORMAL TEMPERATURES REMAIN FAVORED ACROSS MOST OF THE CONUS DURING THE
WEEK-2 PERIOD. THE STRONGEST PROBABILITIES ARE FORECAST ACROSS THE WEST INTO
THE PLAINS WITH PROBABILITIES EXCEEDING 60% ACROSS MOST OF THE REGION AND PARTS
OF THE NORTHERN AND CENTRAL ROCKIES EXCEEDING 70%. EAST OF THE MISSISSIPPI
VALLEY, PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES DECLINE WITH A BROADER AREA
OF NEAR-NORMAL TEMPERATURES FAVORED FOR MUCH OF THE EAST COAST WITH MORE
UNCERTAINTY AMONG THE REFORECAST AND SHORT-TERM BIAS-CORRECTED TOOLS. IN
ALASKA, ABOVE-NORMAL TEMPERATURES ARE FAVORED WITH SOUTHERLY FLOW INTO THE
STATE. ABOVE-NORMAL TEMPERATURES ARE ALSO STRONGLY FAVORED IN HAWAII, AS IN THE
6-10 DAY PERIOD.
THE WEEK-2 PRECIPITATION FORECAST SLIGHTLY FAVORS BELOW-NORMAL PRECIPITATION
ACROSS MUCH OF THE CONUS. SURFACE HIGH PRESSURE IS FORECAST ACROSS MUCH OF THE
PLAINS, MISSISSIPPI VALLEY, AND SOUTHEAST, REDUCING CHANCES FOR PRECIPITATION
ACROSS THESE REGIONS. AN EXCEPTION IS IN PARTS OF SOUTHERN TEXAS WHERE WEAK
ONSHORE FLOW OFF THE GULF OF MEXICO INCREASES CHANCES FOR PRECIPITATION.
ABOVE-NORMAL PRECIPITATION IS FORECAST FOR THE PACIFIC NORTHWEST AND NORTHERN
CALIFORNIA, AS IN THE 6-10 DAY FORECAST, WITH ONSHORE FLOW IN RESPONSE TO THE
UPSTREAM ANOMALOUS TROUGH ACROSS THE NORTHERN PACIFIC AND RIDGE AXIS OVER THE
WEST. THERE IS BETTER AGREEMENT BETWEEN THE GEFS AND ECENS FOR A SLOWER
PROGRESSION OF THE RIDGE EASTWARD RELATIVE TO YESTERDAY BRINGING DRIER
CONDITIONS TO THE SOUTHWEST AND CENTRAL AND SOUTHERN ROCKIES. IN ALASKA,
ABOVE-NORMAL PRECIPITATION REMAINS FORECAST ACROSS THE SOUTHERN PORTIONS OF
ALASKA, WITH BELOW-NORMAL PRECIPITATION FAVORED ACROSS NORTHERN ALASKA.
BELOW-NORMAL PRECIPITATION IS FAVORED IN HAWAII, CONSISTENT WITH THE DYNAMICAL
MODEL GUIDANCE.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 25% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED
ON DAY 11, 35% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 30%
OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: AVERAGE, 3 OUT OF 5, WITH
DIVERGENT SOLUTIONS AMONG THE MODEL GUIDANCE FOR PRECIPITATION REDUCING
CONFIDENCE OFFSET BY VERY GOOD AGREEMENT AMONG TEMPERATURE SOLUTIONS.
FORECASTER: RYAN BOLT
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
DECEMBER 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:
20071122 - 20061203 - 19861210 - 19851218 - 19991223
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:
20071122 - 20061203 - 19861208 - 19851211 - 19761129
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 16 - 20 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A B IDAHO A N 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 N S DAKOTA A N
NEBRASKA A N KANSAS A N OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A N
MINNESOTA N N IOWA A N MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN A N
ILLINOIS A A MISSISSIPPI A N MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA A N NEW YORK A N
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A N NEW JERSEY A N W VIRGINIA A N
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A B FL PENIN A N AK N SLOPE A B
AK ALEUTIAN A N AK WESTERN A N AK INT BSN A B
AK S INT A A AK SO COAST A A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 18 - 24 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 N NEVADA A N
W MONTANA A N E MONTANA A N 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 A W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI A N
ARKANSAS A N LOUISIANA A N WISCONSIN A B
ILLINOIS A N MISSISSIPPI A N MICHIGAN A B
INDIANA A N OHIO A B KENTUCKY A N
TENNESSEE A B ALABAMA A B NEW YORK N B
VERMONT N B NEW HAMP N B MAINE A N
MASS N B CONN N B RHODE IS N B
PENN N B NEW JERSEY N B W VIRGINIA N B
MARYLAND N B DELAWARE N B VIRGINIA N B
N CAROLINA N N S CAROLINA N N GEORGIA N B
FL PNHDL N B FL PENIN N N AK N SLOPE A B
AK ALEUTIAN A N AK WESTERN A N AK INT BSN A B
AK S INT A A AK SO COAST A A AK PNHDL A 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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