782
FXUS06 KWBC 092001
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST MON DECEMBER 09 2024
6-10 DAY OUTLOOK FOR DEC 15 - 19 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 FOUND ACROSS THE NORTHEASTERN CONUS. THIS LEADS TO WEAK
NORTHWESTERLY MID-LEVEL FLOW ACROSS PORTIONS OF THE NORTHERN CONUS. MID-LEVEL
RIDGING IS FORECAST ACROSS THE WESTERN CONUS WITH WEAK POSITIVE 500-HPA HEIGHT
ANOMALIES. 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 SOUTHERN FLORIDA. 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
MUCH OF SOUTHERN ALASKA. MEANWHILE, WEAK ARCTIC MID-LEVEL RIDGING BRINGS
NEAR-NORMAL TEMPERATURES TO PORTIONS OF NORTHERN ALASKA.
THE PRECIPITATION FORECAST IS MORE UNCERTAIN RELATIVE TO THE TEMPERATURE
FORECAST. THERE ARE REDUCED CHANCES FOR ABOVE-NORMAL PRECIPITATION RELATIVE TO
YESTERDAY ACROSS THE PLAINS AND MISSISSIPPI VALLEY WITH NEAR-NORMAL
PRECIPITATION BEING INTRODUCED ACROSS PARTS OF THE MIDDLE AND UPPER MISSISSIPPI
VALLEY. ABOVE-NORMAL PRECIPITATION REMAINS SLIGHTLY FAVORED ACROSS THE GREAT
LAKES, NORTHEAST, AND MID-ATLANTIC WHERE MODELS DEPICT CHANCES FOR A WEAK
CLIPPER SYSTEM TO MOVE THROUGH. IN THE PACIFIC NORTHWEST, ABOVE-NORMAL
PRECIPITATION IS SLIGHTLY FAVORED DUE TO WEAK ONSHORE FLOW WITH THE MID-LEVEL
RIDGE AXIS FORECAST TO BE INLAND. BELOW-NORMAL PRECIPITATION IS FAVORED OVER
MUCH OF THE SOUTHWESTERN CONUS BENEATH MID-LEVEL RIDGING. A WEAK AREA OF
BELOW-NORMAL PRECIPITATION WAS INTRODUCED INTO THE SOUTHEAST WITH SURFACE HIGH
PRESSURE OVER THE REGION. IN ALASKA, ABOVE-NORMAL PRECIPITATION IS FAVORED
ACROSS MUCH OF THE SOUTHERN PARTS OF THE STATE WITH STRONG SOUTHERLY FLOW.
BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS THE NORTHERN HALF OF MAINLAND
ALASKA. BELOW-NORMAL PRECIPITATION IS FAVORED FOR HAWAII, BENEATH MID-LEVEL
POSITIVE HEIGHT ANOMALIES.
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 17 - 23 2024
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 DECEMBER 17-23
MID-LEVEL RIDGING REMAINS FAVORED ACROSS MUCH OF THE WESTERN CONUS. THE
MID-LEVEL RIDGE AXIS IS FORECAST TO BE JUST INLAND ALLOWING ONSHORE
SOUTHWESTERLY FLOW TO DEVELOP 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. WEAK NEGATIVE ANOMALIES 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 WITH
PROBABILITIES EXCEEDING 60% ACROSS MOST OF THE REGION. EAST OF THE ROCKIES,
PROBABILITIES DECLINE BUT REMAIN ELEVATED THROUGH THE MISSISSIPPI VALLEY. IN
THE EASTERN CONUS, A WEAK TILT TOWARDS ABOVE-NORMAL TEMPERATURES ARE FAVORED
ACROSS THE GREAT LAKES AND NORTHEAST. NEAR-NORMAL TEMPERATURES ARE FAVORED
ALONG THE MID-ATLANTIC, SOUTHERN ATLANTIC STATES AND FLORIDA WHERE THERE IS
MORE DISAGREEMENT AMONG THE FORECAST TOOLS WITH WEAK NEGATIVE MID-LEVEL HEIGHT
ANOMALIES DEVELOPING ACROSS FLORIDA. 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 COUNTRY. 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. NEAR-NORMAL PRECIPITATION IS ALSO FAVORED IN PARTS OF THE GREAT
LAKES, NORTHEAST, AND ALONG THE EASTERN SEABOARD WHERE THERE IS UNCERTAINTY IN
HOW THE SYNOPTIC PATTERN WILL EVOLVE. ABOVE-NORMAL PRECIPITATION IS FORECAST
FOR THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA WITH ONSHORE FLOW DEVELOPING
IN RESPONSE TO THE RIDGE AXIS MOVING INLAND, PARTICULARLY BY THE SECOND HALF OF
WEEK-2. THE GEFS IS RELATIVELY STRONGER AND MORE PROGRESSIVE WITH THE PATTERN
BRINGING ABOVE-NORMAL PRECIPITATION FURTHER INLAND WHILE THE ECENS BASED TOOLS
ARE SLOWER AND MAINTAIN DRIER CONDITIONS ACROSS THE INTERIOR WEST. 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: 5% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 30% 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:
19881208 - 20041215 - 19981216 - 19851220 - 20021126
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:
19881207 - 19891206 - 19881212 - 19851219 - 19981215
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 15 - 19 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A N
SRN CALIF A B IDAHO A N NEVADA A B
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 N S DAKOTA A N
NEBRASKA A B KANSAS A N OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A N
MINNESOTA A A IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA A N WISCONSIN A A
ILLINOIS A N MISSISSIPPI A B MICHIGAN A A
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A B ALABAMA A B NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A A NEW JERSEY A A W VIRGINIA A N
MARYLAND A A DELAWARE A A VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A B
FL PNHDL A N FL PENIN A N AK N SLOPE N B
AK ALEUTIAN A A AK WESTERN A N AK INT BSN N B
AK S INT A A AK SO COAST A A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 17 - 23 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 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 N S DAKOTA A B
NEBRASKA A B KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS A A W TEXAS A N
MINNESOTA A N IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA A B WISCONSIN A N
ILLINOIS A B MISSISSIPPI A B MICHIGAN A N
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A B 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 N N NEW JERSEY N N W VIRGINIA N N
MARYLAND N N DELAWARE N N VIRGINIA N N
N CAROLINA N N S CAROLINA N B 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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