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FXUS06 KWBC 042019
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 04 2023
6-10 DAY OUTLOOK FOR DEC 10 - 14 2023
TODAY’S ENSEMBLE MEAN MODEL SOLUTIONS ARE ONLY IN FAIR AGREEMENT ON THE 500-HPA
MEAN FLOW PATTERN ACROSS NORTH AMERICA AND ADJACENT OCEANIC AREAS DURING THE
6-10 DAY FORECAST PERIOD. ANOMALY CORRELATION SCORES FOR THE PAST 60 DAYS DO
NOT SIGNIFICANTLY FAVOR ONE MODEL OVER ANOTHER, HENCE THE MANUAL HEIGHT BLEND
IS COMPOSED OF NEARLY EQUAL WEIGHTS OF THE 00Z RUNS OF THE GFS, ECMWF, AND
CANADIAN ENSEMBLE MEANS. THE MANUAL HEIGHT BLEND DEPICTS MID-LEVEL RIDGING AND
ABOVE NORMAL 500-HPA HEIGHTS OVER FAR EASTERN SIBERIA, AND MID-LEVEL TROUGHING
AND MODESTLY BELOW NORMAL 500-HPA HEIGHTS OVER ALASKA. A BROAD, LOW-AMPLITUDE
RIDGE AND ABOVE NORMAL HEIGHTS ARE PREDICTED OVER THE EASTERN PACIFIC AND
WESTERN CONTIGUOUS U.S. (CONUS). DOWNSTREAM, OVER THE EAST-CENTRAL CONUS, THE
MANUAL HEIGHT BLEND DEPICTS A MID-LEVEL TROUGH, WHILE RESIDUAL MID-LEVEL
RIDGING AND ABOVE NORMAL 500-HPA HEIGHTS ARE INDICATED NEAR AND OFF THE EAST
COAST.
THE GREATEST UNCERTAINTY AMONG TODAY’S MODEL SOLUTIONS IS NEAR THE WEST COAST
OF THE CONUS. THE 00Z GEFS INDICATES FAST WESTERLY (ONSHORE) FLOW ACROSS MOST
OF THIS REGION, WHILE THE 00Z ECMWF ENSEMBLE DEPICTS SIGNIFICANT MID-LEVEL
RIDGING. THE LATTER SOLUTION FAVORS THE STEERING OF THE PACIFIC JET STREAM AND
STORM TRACK FARTHER NORTH INTO WESTERN CANADA, WITH MUCH DRIER CONDITIONS FOR
THE WESTERN CONUS. THE 00Z CANADIAN ENSEMBLE MEAN SOLUTION INDICATES MID-LEVEL
RIDGING AND ACCOMPANYING ABOVE NORMAL HEIGHTS OVER THE NORTHEASTERN PACIFIC.
THE 6-10 DAY TEMPERATURE OUTLOOK FAVORS ABOVE NORMAL TEMPERATURES OVER MOST
AREAS WEST OF THE CONTINENTAL DIVIDE, THE NORTHERN AND CENTRAL PLAINS, AND
ADJACENT PORTIONS OF THE UPPER MISSISSIPPI VALLEY. PROBABILITIES FAVORING ABOVE
NORMAL TEMPERATURES EXCEED 60% OVER PORTIONS OF CALIFORNIA. THIS AGREES WELL
WITH GEFS AND ECMWF ENSEMBLE MEAN REFORECAST TEMPERATURES AND TO A LESSER
DEGREE, THE CANADIAN REFORECAST TEMPERATURE TOOL. ABOVE NORMAL TEMPERATURE
CHANCES ARE INCREASED OVER THE EASTERN HALF OF THE GREAT LAKES REGION, THE
UPPER OHIO VALLEY, THE CENTRAL AND NORTHERN APPALACHIANS, AND THE ATLANTIC
COASTAL PLAIN FROM MAINE THROUGH NORTH CAROLINA. PROBABILITIES FAVORING ABOVE
NORMAL TEMPERATURES EXCEED 60% OVER THE NORTHEAST. THIS IS IN RESPONSE TO A
DEPARTING 500-HPA RIDGE, AND AN UPSTREAM MID-LEVEL TROUGH OVER THE EAST-CENTRAL
CONUS. A RELATIVELY SMALL AREA OF FAVORED ABOVE NORMAL TEMPERATURES IS
INDICATED OVER SOUTHERN FLORIDA. ODDS FAVOR BELOW NORMAL TEMPERATURES FROM
SOUTHERN TEXAS EASTWARD ACROSS THE CENTRAL GULF COAST, CONSISTENT WITH
AUTO-TEMPERATURE AND CONSOLIDATED TEMPERATURE GUIDANCE. BELOW NORMAL
TEMPERATURE CHANCES ARE ALSO INCREASED OVER MOST OF ALASKA, DUE TO A MID-LEVEL
TROUGH AND WIDESPREAD NORTHERLY FLOW PREDICTED OVER THE STATE. PROBABILITIES
FAVORING BELOW NORMAL TEMPERATURES EXCEED 60% OVER PARTS OF SOUTHWESTERN
ALASKA. FOR HAWAII, RELATIVELY WARM SEA-SURFACE TEMPERATURES AND A VERY WEAK
MID-LEVEL HEIGHT ANOMALY PATTERN FAVOR ABOVE NORMAL TEMPERATURES FOR THE
ISLANDS, SUPPORTED BY THE ERF-CON TEMPERATURE TOOL.
THE 6-10 DAY PRECIPITATION OUTLOOK FAVORS A SLIGHT TILT IN THE ODDS TOWARDS
ABOVE NORMAL PRECIPITATION FROM THE PACIFIC NORTHWEST EASTWARD ACROSS THE
NORTHERN INTERMOUNTAIN REGION, NORTHERN ROCKIES, AND NORTHERN HIGH PLAINS,
ASSOCIATED WITH PACIFIC ONSHORE FLOW, AND IS CONSISTENT WITH THE STATISTICAL
PRECIPITATION ANALOG FROM THE MANUAL HEIGHT BLEND. ABOVE NORMAL PRECIPITATION
IS ALSO FAVORED OVER APPROXIMATELY THE EASTERN QUARTER OF THE CONUS, IN ADVANCE
OF A MID-LEVEL TROUGH. A SMALL AREA OF ABOVE NORMAL PRECIPITATION IS ALSO
INDICATED OVER FAR SOUTHERN TEXAS. BELOW NORMAL PRECIPITATION CHANCES ARE
ELEVATED OVER APPROXIMATELY THE SOUTHWESTERN QUARTER AND CENTRAL THIRD OF THE
CONUS, BASED ON GEFS AND ECMWF ENSEMBLE MEAN REFORECAST PRECIPITATION TOOLS. IN
ALASKA, BELOW NORMAL PRECIPITATION IS FAVORED OVER NORTHWESTERN SECTIONS OF THE
STATE, ASSOCIATED WITH DRIER NORTHERLY ANOMALOUS FLOW. THERE ARE INCREASED
CHANCES OF ABOVE NORMAL PRECIPITATION OVER CENTRAL AND EASTERN ALASKA,
ASSOCIATED WITH A MID-LEVEL TROUGH, BELOW NORMAL 500-HPA HEIGHTS, AND ONSHORE
FLOW. FOR HAWAII, NEAR NORMAL PRECIPITATION IS FAVORED FOR ALL ISLANDS EXCEPT
THE BIG ISLAND, WHERE THERE IS A SLIGHT TILT IN THE ODDS TOWARDS BELOW NORMAL
PRECIPITATION. THIS IS BASED ON A COMPROMISE BETWEEN THE AUTO-PRECIPITATION AND
ERF-CON 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: NEAR AVERAGE, 3 ON A SCALE OF 1-5,
BASED ON SIGNIFICANT DIFFERENCES AMONG THE ENSEMBLE MEAN MID-LEVEL HEIGHT
FIELDS, AND RELATED DISCREPANCIES AMONG THE VARIOUS SURFACE TEMPERATURE AND
PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR DEC 12 - 18 2023
TODAY’S 00Z ENSEMBLE MEAN SOLUTIONS FROM THE GFS AND ECMWF MODELS ARE IN FAIRLY
GOOD AGREEMENT ON THE PREDICTED LARGE-SCALE 500-HPA HEIGHT PATTERN ACROSS THE
FORECAST DOMAIN. THESE SOLUTIONS DEPICT A BROAD ANOMALOUS RIDGE OVER MOST OF
THE CONUS, AND A SMALLER-SCALE ANOMALOUS RIDGE IN THE GENERAL VICINITY OF
40N/165W (NORTH-NORTHWEST OF THE HAWAIIAN ISLANDS). NEGATIVE 500-HPA HEIGHT
ANOMALIES ARE INDICATED OVER MUCH OF CANADA. THE 00Z CANADIAN ENSEMBLE MEAN
DIFFERS FROM THE OTHER TWO ENSEMBLE MEANS IN FORECASTING A MUCH STRONGER
ANOMALOUS RIDGE CENTERED NEAR 40N/160W, AND IN PREDICTING VERY WEAK 500-HPA
HEIGHT ANOMALIES OVER THE WESTERN AND CENTRAL CONUS.
THE 8-14 DAY TEMPERATURE OUTLOOK FAVORS ABOVE NORMAL TEMPERATURES ACROSS MOST
OF THE LOWER 48 STATES, EXCEPT FOR A CORRIDOR OF NEAR NORMAL TEMPERATURES
FAVORED OVER THE SOUTHEAST. THIS IS ASSOCIATED WITH A RELATIVELY MILD FLOW OF
PACIFIC AIR AND FAST LOW-AMPLITUDE FLOW. PROBABILITIES FAVORING ABOVE NORMAL
TEMPERATURES EXCEED 60% OVER PORTIONS OF THE NORTH-CENTRAL STATES. BELOW NORMAL
TEMPERATURES ARE FAVORED ACROSS NEARLY ALL OF ALASKA (EXCEPT THE ALEUTIANS
WHERE NEAR NORMAL TEMPERATURES ARE INDICATED). THIS IS DUE TO THE PROXIMITY OF
A BROAD MID-LEVEL TROUGH AND BELOW NORMAL 500-HPA HEIGHTS, WITH THIS TROUGH
PREDICTED TO BE SOMEWHAT MORE AMPLIFIED IN WEEK-2 THAN DURING THE EARLIER 6-10
DAY PERIOD. ABOVE NORMAL TEMPERATURES ARE FAVORED ACROSS THE HAWAIIAN ISLANDS,
CONSISTENT WITH ERF-CON TEMPERATURE GUIDANCE.
THE 8-14 DAY PRECIPITATION OUTLOOK FAVORS ABOVE NORMAL PRECIPITATION OVER THE
WEST COAST STATES, ASSOCIATED WITH EXPECTED ONSHORE FLOW. PREDICTED SURFACE
HIGH PRESSURE OVER THE SOUTHEAST LEADS TO MOIST, EASTERLY FLOW AND INCREASED
CHANCES OF ABOVE NORMAL PRECIPITATION FOR FLORIDA. RETURN FLOW AROUND THIS
SURFACE ANTICYCLONE TILTS THE ODDS TOWARDS ABOVE NORMAL PRECIPITATION FOR
PORTIONS OF THE SOUTHERN AND CENTRAL PLAINS, AND MIDDLE TO UPPER MISSISSIPPI
VALLEY, ASSOCIATED WITH AN EXPECTED INCREASE IN LOW-LEVEL GULF MOISTURE. MUCH
OF THE REMAINDER OF THE CONUS IS FAVORED TO HAVE BELOW NORMAL PRECIPITATION,
SUPPORTED BY GOOD AGREEMENT BETWEEN THE AUTO-PRECIPITATION AND CONSOLIDATED
PRECIPITATION TOOLS. THIS IS ALSO CONSISTENT WITH PREDICTED WIDESPREAD
ANOMALOUS MID-LEVEL RIDGING AND POSITIVE 500-HPA HEIGHT ANOMALIES. THE WEEK-2
PRECIPITATION OUTLOOK FOR ALASKA FAVORS BELOW NORMAL PRECIPITATION CHANCES
ACROSS FAR WESTERN ALASKA, AND MOSTLY ABOVE NORMAL PRECIPITATION CHANCES
ELSEWHERE, ASSOCIATED WITH A SIGNIFICANT MID-LEVEL TROUGH, BELOW NORMAL 500-HPA
HEIGHTS, AND CYCLONIC CURVATURE. NEAR NORMAL PRECIPITATION CHANCES ARE FAVORED
ACROSS HAWAII, BASED ON A COMPROMISE BETWEEN THE ERF-CON PRECIPITATION GUIDANCE
AND THE AUTO-PRECIPITATION TOOL.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 33% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: ABOVE AVERAGE, 4 ON A SCALE OF
1-5, BASED ON FAIRLY GOOD AGREEMENT BETWEEN GFS AND ECMWF ENSEMBLE MEAN 500-HPA
HEIGHT FORECASTS, BUT OFFSET BY UNCERTAINTIES RELATED TO THE DIFFERENCES
FORECAST BY THE 00Z CANADIAN ENSEMBLE MEAN SOLUTION.
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
DECEMBER 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:
19881127 - 20031213 - 19811201 - 19621120 - 19601118
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:
19881127 - 20031213 - 19621120 - 19601118 - 19531208
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 10 - 14 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A N NRN CALIF A B
SRN CALIF A B IDAHO A N NEVADA A B
W MONTANA A A E MONTANA A A WYOMING A N
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO N B N DAKOTA A N S DAKOTA A N
NEBRASKA A B KANSAS A B OKLAHOMA N B
N TEXAS N B S TEXAS B N W TEXAS N B
MINNESOTA A B IOWA A B MISSOURI N B
ARKANSAS N B LOUISIANA B B WISCONSIN N N
ILLINOIS N B MISSISSIPPI B B MICHIGAN N A
INDIANA N N OHIO A A KENTUCKY N N
TENNESSEE N B ALABAMA N 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 A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA N A GEORGIA N A
FL PNHDL N A FL PENIN N A AK N SLOPE B A
AK ALEUTIAN B N AK WESTERN B N AK INT BSN B A
AK S INT B A AK SO COAST B A AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 12 - 18 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A A IDAHO A N NEVADA A N
W MONTANA A N E MONTANA A B WYOMING A N
UTAH A N ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A B S DAKOTA A B
NEBRASKA A N KANSAS A N OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A N
MINNESOTA A B IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA A B WISCONSIN A B
ILLINOIS A N MISSISSIPPI A B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA N B 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 N B S CAROLINA N N GEORGIA N B
FL PNHDL N N FL PENIN A A AK N SLOPE B N
AK ALEUTIAN B N AK WESTERN B B 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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