945
FXUS06 KWBC 312002
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 31 2024
6-10 DAY OUTLOOK FOR JAN 06 - 10 2025
A PATTERN CHANGE IS FORECAST DURING EARLY JANUARY AS A FULL-LATITUDE 500-HPA
RIDGE EXTENDS NORTH FROM THE WEST COAST TO ALASKA AND HIGH LATITUDE BLOCKING
BECOMES ESTABLISHED. THE GEFS DEPICTS A HIGHLY NEGATIVE ARCTIC OSCILLATION (AO)
OF -4 STANDARD DEVIATIONS BY THE SECOND WEEK OF JANUARY. THE GEFS, ECENS, AND
CMCE ARE IN EXCELLENT AGREEMENT AND REMAIN CONSISTENT THAT ARCTIC HIGH PRESSURE
SHIFTS SOUTH FROM CANADA BY DAY 6 (JANUARY 6) WITH A SECOND ARCTIC HIGH
FOLLOWING BY DAY 10. THE ANOMALOUS MID-LEVEL TROUGH, CROSS POLAR FLOW, AND TWO
ARCTIC HIGHS SHIFTING SOUTHWARD STRONGLY SUPPORT BELOW-NORMAL TEMPERATURES
ACROSS THE EASTERN TWO-THIRDS OF THE CONTIGUOUS U.S. (CONUS). LARGE
BELOW-NORMAL TEMPERATURE PROBABILITIES (MORE THAN 80 PERCENT) ARE FORECAST FROM
THE LOWER AND MIDDLE MISSISSIPPI VALLEY EASTWARD TO THE MID-ATLANTIC WHERE THE
ENSEMBLE MEAN SOLUTIONS HAVE 5-DAY TEMPERATURES AVERAGING NEAR OR MORE THAN 10
DEGREES F BELOW NORMAL. AN AMPLIFIED 500-HPA RIDGE AND POSITIVE HEIGHT
DEPARTURES SUPPORT INCREASED ABOVE-NORMAL TEMPERATURES ACROSS THE PACIFIC
NORTHWEST, CALIFORNIA, AND PORTIONS OF THE GREAT BASIN.
ON DAY 6, A LOW PRESSURE SYSTEM IS FORECAST TO TRACK ACROSS THE MID-ATLANTIC.
RECENT MODEL RUNS HAVE TRENDED TOWARDS A MORE SUPPRESSED OR WEAKER LOW PRESSURE
SYSTEM AS IT ENCOUNTERS CONFLUENT MID-LEVEL FLOW. THEREFORE, NEAR NORMAL
PRECIPITATION IS MORE LIKELY FOR THE MID-ATLANTIC WITH INCREASED ABOVE-NORMAL
PRECIPITATION PROBABILITIES LIMITED TO THE COASTAL SOUTHEAST, GULF COAST, AND
FLORIDA. THIS LEAN TOWARDS ABOVE-NORMAL PRECIPITATION CLOSER TO THE GULF COAST
IS ALSO RELATED TO THE POTENTIAL FOR LOW PRESSURE DEVELOPMENT LATER IN THE 6-10
DAY PERIOD. NEAR NORMAL PRECIPITATION REMAINS FAVORED DOWNWIND OF THE GREAT
LAKES DUE TO LAKE-EFFECT SNOW. SINCE PRECIPITATION WITH A LOW PRESSURE SYSTEM
IS FORECAST TO BE TIMING OFF BY DAY 6, BELOW-NORMAL PRECIPITATION IS FAVORED
FOR PARTS OF THE OHIO AND TENNESSEE VALLEYS. UPSLOPE FLOW ALONG WITH SHORTWAVE
TROUGHS WITHIN THE NORTHWEST FLOW ALOFT INCREASE ABOVE-NORMAL PRECIPITATION
CHANCES FOR THE GREAT PLAINS WEST TO THE ROCKIES. AN AMPLIFIED 500-HPA RIDGE
NEAR THE WEST COAST LEADS TO AN INCREASED CHANCE OF BELOW-NORMAL PRECIPITATION
ACROSS THE PACIFIC NORTHWEST, GREAT BASIN, CALIFORNIA, AND THE SOUTHWEST.
ENSEMBLE MEAN SOLUTIONS ARE IN GOOD AGREEMENT FEATURING AN AMPLIFIED 500-HPA
TROUGH (RIDGE) OVER THE ALEUTIANS (EASTERN MAINLAND ALASKA). THIS LONGWAVE
PATTERN YIELDS INCREASED ABOVE-NORMAL TEMPERATURES PROBABILITIES FOR MUCH OF
ALASKA. ENHANCED ONSHORE FLOW FAVORS ABOVE-NORMAL PRECIPITATION FOR THE
MAJORITY OF ALASKA EXCEPT FOR THE NORTH SLOPE WHERE NEAR- TO BELOW-NORMAL
PRECIPITATION IS MORE LIKELY.
BASED ON THE GEFS AND ECENS, ABOVE-NORMAL TEMPERATURES ARE STRONGLY FAVORED FOR
HAWAII. THE CONSOLIDATION SUPPORTS ELEVATED ABOVE-NORMAL PRECIPITATION
PROBABILITIES FOR THE STATE.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 40% 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, DUE TO
A HIGHLY AMPLIFIED LONGWAVE PATTERN AND GOOD AGREEMENT AMONG THE TEMPERATURE
AND PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR JAN 08 - 14 2025
THE HIGHLY AMPLIFIED LONGWAVE PATTERN, WITH A FULL-LATITUDE RIDGE EXTENDING
FROM THE WEST COAST NORTH TO THE BEAUFORT SEA AND A VERY ANOMALOUS TROUGH OVER
THE EASTERN HALF OF THE CONUS, IS FORECAST TO PERSIST THROUGH AT LEAST THE
SECOND WEEK OF JANUARY. THE GEFS AND ECENS FEATURE NEGATIVE 500-HPA HEIGHT
DEPARTURES OF -180 TO -210 METERS OVER THE MID-ATLANTIC FOR THE 7-DAY PERIOD.
ALSO, SUBSTANTIAL 500-HPA HEIGHT ANOMALIES OF -30 TO -60 METERS EXTEND AS FAR
SOUTH AS THE FLORIDA KEYS. THESE ENSEMBLE MEANS DEPICT THE MID-LEVEL TROUGH
PEAKING FROM DAYS 9 TO 11 (JANUARY 9-11) WHEN 500-HPA HEIGHT ANOMALIES ARE
AROUND -240 METERS CENTERED ACROSS THE MID-ATLANTIC. ANOTHER REMARKABLE FEATURE
IN THE 500-HPA HEIGHT ANOMALY FIELD FROM THE GEFS IS THE PREDICTED +270 METER
DEPARTURE OVER SOUTHERN GREENLAND WHICH IS ASSOCIATED WITH THE STRONG HIGH
LATITUDE BLOCK. EARLY IN WEEK-2, ARCTIC HIGH PRESSURE IS FORECAST TO EXPAND
SOUTHWARD AND OVERSPREAD NEARLY ALL OF THE CENTRAL AND EASTERN CONUS WHERE
BELOW-NORMAL TEMPERATURES ARE FAVORED. BASED ON EXCELLENT MODEL AGREEMENT AND
CONSISTENCY, THE GEFS AND ECENS REFORECAST TOOLS, AND THE ANALOG TOOL DERIVED
FROM THE MANUAL 500-HPA HEIGHT BLEND, A LARGE AREA WITH BELOW-NORMAL
TEMPERATURE PROBABILITIES EXCEEDING 80 PERCENT EXTENDS FROM THE OHIO VALLEY
SOUTH TO THE GULF COAST. A GREATER THAN 80 PERCENT CHANCE OF BELOW-NORMAL
TEMPERATURES COVERS A LARGE AREA INCLUDING THE MID-ATLANTIC, OHIO VALLEY, AND
SOUTHEAST WITH THE GEFS AND ECENS PREDICTING 7-DAY TEMPERATURES AVERAGING NEAR
15 DEGREES F BELOW NORMAL. THE INCREASED CHANCE OF BELOW-NORMAL TEMPERATURES
EXTENDS WEST TO THE HIGH PLAINS, BUT FORECAST CONFIDENCE IS LOWEST FOR THIS
REGION SINCE THE ECENS DEPICTS A WARMING TREND LATER IN WEEK-2. DUE TO POSITIVE
500-HPA HEIGHT DEPARTURES, ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR THE
WESTERN THIRD OF THE CONUS WITH INCREASING PROBABILITIES CLOSER TO THE WEST
COAST.
NEAR TO BELOW-NORMAL PRECIPITATION IS FAVORED FOR MOST AREAS FROM THE
MISSISSIPPI VALLEY TO THE EAST COAST AS ANOMALOUS NORTHERLY FLOW PREVAILS. THE
GREATEST CHANCE FOR BELOW-NORMAL PRECIPITATION IS CENTERED ACROSS THE LOWER
OHIO VALLEY WITH ANY STORM TRACK DISPLACED SOUTH OR WELL EAST OF THIS REGION.
ALSO, THIS IS SUPPORTED BY THE ANALOG TOOL FROM THE MANUAL 500-HPA HEIGHT
BLEND. PERIODS OF ENHANCED LAKE-EFFECT SNOW CONTINUE TO FAVOR NEAR NORMAL
PRECIPITATION DOWNWIND OF THE GREAT LAKES. AT THE BASE OF THE HIGH AMPLITUDE
TROUGH OVER EASTERN NORTH AMERICA, THE GEFS AND ECENS DEPICT ONE OR MORE LOW
PRESSURE SYSTEM TRACKING ACROSS THE GULF OF MEXICO WHICH ELEVATES ABOVE-NORMAL
PRECIPITATION PROBABILITIES FOR ALONG THE GULF COAST AND MUCH OF FLORIDA.
ALTHOUGH TOTAL 7-DAY PRECIPITATION AMOUNTS ARE LIKELY TO BE LOW (LESS THAN 0.5
INCH, LIQUID EQUIVALENT), PRECIPITATION TOOLS DEPICT AN INCREASED CHANCE OF
ABOVE-NORMAL PRECIPITATION FOR PORTIONS OF THE NORTHERN AND CENTRAL GREAT
PLAINS. ALONG AND TO THE EAST OF THE HIGH AMPLITUDE RIDGE AXIS, BELOW-NORMAL
PRECIPITATION IS FAVORED FOR THE PACIFIC NORTHWEST, GREAT BASIN, CALIFORNIA,
AND THE SOUTHWEST.
DOWNSTREAM OF THE AMPLIFIED TROUGH OVER THE ALEUTIANS, ENHANCED SOUTHERLY FLOW
FAVORS ABOVE-NORMAL TEMPERATURES AND ABOVE-NORMAL PRECIPITATION FOR ALL OF
ALASKA. THE LARGEST ABOVE-NORMAL PRECIPITATION PROBABILITIES (MORE THAN 50
PERCENT) ARE FORECAST FOR SOUTHEASTERN ALASKA WHICH IS SUPPORTED BY THE
PREDICTED SURFACE FLOW AND PRECIPITATION TOOLS.
BASED ON THE GEFS AND ECENS, INCREASED CHANCES OF ABOVE-NORMAL TEMPERATURES AND
ABOVE-NORMAL PRECIPITATION ARE FORECAST FOR HAWAII.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 30% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 40% 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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
A HIGHLY AMPLIFIED LONGWAVE PATTERN AND EXCELLENT AGREEMENT AMONG THE
TEMPERATURE TOOLS. HOWEVER, THERE IS UNCERTAINTY IN THE PRECIPITATION OUTLOOK
FOR THE GULF COAST STATES AND EASTERN CONUS DUE TO THE POTENTIAL FOR LOW
PRESSURE DEVELOPMENT.
FORECASTER: BRAD PUGH
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
JANUARY 16.
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:
19591226 - 20031226 - 20091223 - 19961212 - 19950114
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:
20031226 - 20091223 - 19521210 - 19691210 - 19871210
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR JAN 06 - 10 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A B
SRN CALIF A B IDAHO N B NEVADA A B
W MONTANA N A E MONTANA B A WYOMING N A
UTAH N B ARIZONA N B COLORADO B A
NEW MEXICO B A N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS B N OKLAHOMA B N
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA B N IOWA B N MISSOURI B N
ARKANSAS B B LOUISIANA B A WISCONSIN B N
ILLINOIS B N MISSISSIPPI B B MICHIGAN B N
INDIANA B N OHIO B N KENTUCKY B N
TENNESSEE B N ALABAMA B N NEW YORK B N
VERMONT B B NEW HAMP B B MAINE B B
MASS B B CONN B N RHODE IS B N
PENN B N NEW JERSEY B N W VIRGINIA B N
MARYLAND B N DELAWARE B N VIRGINIA B N
N CAROLINA B N S CAROLINA B N GEORGIA B N
FL PNHDL B A FL PENIN B A AK N SLOPE A A
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A
AK S INT A A AK SO COAST A A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR JAN 08 - 14 2025
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A B
SRN CALIF A B IDAHO A B NEVADA A B
W MONTANA A N E MONTANA N A WYOMING A A
UTAH A B ARIZONA A B COLORADO B A
NEW MEXICO B N N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS B N OKLAHOMA B B
N TEXAS B B S TEXAS B A W TEXAS B N
MINNESOTA B N IOWA B N MISSOURI B B
ARKANSAS B B LOUISIANA B B WISCONSIN B N
ILLINOIS B B MISSISSIPPI B B MICHIGAN B N
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE B B ALABAMA B B NEW YORK B N
VERMONT B N NEW HAMP B N MAINE B N
MASS B N CONN B N RHODE IS B N
PENN B N NEW JERSEY B N W VIRGINIA B N
MARYLAND B N DELAWARE B N VIRGINIA B B
N CAROLINA B B S CAROLINA B B GEORGIA B B
FL PNHDL B A FL PENIN B A AK N SLOPE A A
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A
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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