696
FXUS06 KWBC 212003
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST THU DECEMBER 21 2023
6-10 DAY OUTLOOK FOR DEC 27 - 31 2023
TODAY’S GEFS, CMCE, AND ECMWF SOLUTIONS OF THE 500-HPA HEIGHT ANOMALY FIELD
DEPICT DEEP TROUGHING OVER THE NORTH PACIFIC, WEAK NEGATIVE HEIGHT ANOMALIES
OVER THE SOUTH-CENTRAL AND SOUTHEASTERN CONTIGUOUS U.S. (CONUS), AND EXPANSIVE
POSITIVE HEIGHT ANOMALIES COVERING MUCH OF THE NORTHERN CONUS AND ALMOST ALL OF
CANADA. THIS SETUP FAVORS ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE CONUS,
ABOVE-NORMAL PRECIPITATION FOR BOTH COASTS AND GENERALLY BELOW-NORMAL
PRECIPITATION FOR THE REST OF THE LOWER 48.
WITH POSITIVE HEIGHT ANOMALIES OVER CANADA CONFINING COLDER AIR TO HIGHER
LATITUDES, ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE CONUS,
ESPECIALLY FOR THE NORTHERN TIER AND ALONG THE WEST COAST WHERE PROBABILITIES
EXCEED 70%. AS COOLER PACIFIC AIR MOVES EASTWARD ACROSS AND OUT OF THE DESERT
SOUTHWEST, NEAR-NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF NEW MEXICO AS WELL
AS PORTIONS OF THE SOUTHERN PLAINS, SOUTHERN MISSISSIPPI VALLEY, AND SOUTHEAST
U.S, WITH A SLIGHT TILT TOWARDS BELOW-NORMAL TEMPERATURES ALONG THE GULF COAST.
RIDGING OVER CANADA AND TROUGHING OVER THE NORTH PACIFIC FAVORS A SPLIT
FORECAST FOR ALASKA, WITH INCREASED BELOW (ABOVE)-NORMAL TEMPERATURE
PROBABILITIES INDICATED FOR WESTERN (EASTERN) PORTIONS OF THE STATE. FOR HAWAII
FORECAST TOOLS FAVOR NEAR-NORMAL TEMPERATURES FOR MOST OF THE ISLANDS EXCEPT
FOR THE BIG ISLAND AND EASTERN MAUI, WHICH TILTS SLIGHTLY TOWARDS BELOW-NORMAL
TEMPERATURES.
DEEP TROUGHING OVER THE NORTH PACIFIC AND A SECONDARY TROUGH OVER THE EASTERN
CONUS RESULTS IN A WET PATTERN FOR THE COASTS, ESPECIALLY THE WEST COAST. IN
THE EAST PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION ARE HIGHER FOR THE
FLORIDA PENINSULA, BUT OVERALL PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION IN
THE EAST HAVE DIMINISHED QUITE A BIT OVER THE LAST COUPLE DAYS. ABOVE-NORMAL
PRECIPITATION REMAINS FAVORED FOR THE WEST COAST, PARTICULARLY FOR NORTHERN
CALIFORNIA, BUT PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION DO NOT EXTEND VERY
FAR PAST THE SIERRA NEVADAS. BELOW-NORMAL PRECIPITATION IS INDICATED FROM THE
GREAT BASIN EAST TO ROUGHLY THE APPALACHIANS AND GREAT LAKES, WITH HIGHER ODDS
FOR THE NORTHERN PLAINS, NORTHERN ROCKIES, AND THE LOWER MISSISSIPPI VALLEY.
SOUTHERLY FLOW OFF THE NORTH PACIFIC TILTS SOUTHERN ALASKA TOWARDS ABOVE-NORMAL
PRECIPITATION,WHILE NEAR-NORMAL PRECIPITATION IS MOST LIKELY FOR THE REST OF
THE STATE. BELOW-NORMAL PRECIPITATION IS FAVORED FOR THE HAWAIIAN ISLANDS,
SUPPORTED BY THE ERF-CON HAWAII TOOL.
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, WITH
VERY GOOD AGREEMENT AMONG ENSEMBLE MODELS AND FORECAST TOOLS, OFFSET BY LARGE
SHIFTS IN PRECIPITATION GUIDANCE RELATIVE TO YESTERDAY.
8-14 DAY OUTLOOK FOR DEC 29, 2023 - JAN 04, 2024
THE WEEK-2 FORECAST PERIOD FEATURES A SIMILAR SYNOPTIC PICTURE TO WHAT IS SEEN
IN THE 6-10 DAY PERIOD, WITH A SLIGHT EASTWARD PROGRESSION OF THE TROUGH OVER
THE EASTERN CONUS. MODEL 500-HPA HEIGHT ANOMALIES ARE DIMINISHED RELATIVE TO
THE EARLY PERIOD FOR THE MOST PART, ALTHOUGH MODEL SOLUTIONS FAVOR A SLIGHT
DEEPENING OF THE TROUGHING OVER THE SOUTHEAST U.S. AND A WEAKER TROUGH OVER THE
NORTH PACIFIC. THIS FAVORS CONTINUED ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE
CONUS, AND ABOVE-NORMAL PRECIPITATION FOR THE SOUTHWEST CONUS.
THE CONTINUED POSITIVE HEIGHT ANOMALIES OVER CANADA FAVOR A PERSISTENCE OF
ABOVE-NORMAL TEMPERATURES FOR MOST OF THE CONUS. THE HIGHEST PROBABILITIES
(>60%) ARE OVER THE UPPER MIDWEST, AND OVERALL PROBABILITIES ARE LOWER RELATIVE
TO THE 6-10 DAY PERIOD. FALLING 500-HPA HEIGHTS OVER THE SOUTHEAST U.S.
INCREASE NORTHERLY FLOW INTO THE GULF COAST, RESULTING IN A SLIGHT TILT TOWARDS
BELOW-NORMAL TEMPERATURES FOR THAT REGION AS WELL AS PARTS OF THE MID-ATLANTIC.
AS RIDGING OVER CANADA RETROGRESSES SLIGHTLY, THE AREA OF ABOVE-NORMAL
TEMPERATURES FAVORED SPREADS WESTWARD TO INCLUDE MOST OF THE STATE OF ALASKA,
WITH BELOW-NORMAL TEMPERATURES INDICATED ONLY FOR PARTS OF THE WESTERN COAST.
FOR HAWAII, COOLER TEMPERATURES ARE FAVORED FOR THE BIG ISLAND, WHILE THE REST
OF THE ISLANDS TILT TOWARDS NEAR-NORMAL TEMPERATURES.
ALTHOUGH MODEL SOLUTIONS FAVOR A WEAKENING OF THE TROUGH OVER THE NORTH PACIFIC
DURING WEEK-2, PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION FOR THE WEST COAST
REMAIN AND EXPAND EASTWARD INTO THE SOUTHERN PLAINS AS POSITIVE HEIGHT
ANOMALIES OVER CANADA SHIFT TO THE EAST. THE TROUGH OVER THE SOUTHEAST U.S. IS
ALSO FAVORED TO SHIFT EASTWARD MOVING THE BULK OF PRECIPITATION OFFSHORE,
RESULTING IN AN EASTWARD SHIFT IN THE AREA FAVORED FOR BELOW-NORMAL
PRECIPITATION TO EXTEND TO THE COAST, WITH WIDESPREAD COVERAGE FOR MOST OF THE
NORTHERN CONUS, THE MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, AND SOUTHEAST
U.S. ONLY THE GULF COAST CONTINUES TO TILT TOWARDS ABOVE-NORMAL PRECIPITATION.
ALASKA CONTINUES TO TILT TOWARD ABOVE-NORMAL PRECIPITATION FOR SOUTHERN AND
SOUTHEASTERN PORTIONS OF THE STATE WITH CONTINUED MOIST ONSHORE FLOW OFF THE
GULF OF ALASKA, BUT ENCROACHING POSITIVE HEIGHT ANOMALIES MOVING WEST OUT OF
CANADA RESULT IN BELOW-NORMAL PRECIPITATION FAVORED FOR THE NORTHEAST CORNER OF
THE STATE. THE ERF-CON CONTINUES TO INDICATE BELOW-NORMAL PRECIPITATION FOR THE
SOUTHEASTERN HAWAIIAN ISLANDS, WHILE NEAR-NORMAL PRECIPITATION IS FAVORED FOR
THE NORTHWESTERN ISLANDS.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 38% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 37% 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: ABOVE AVERAGE, 4 OUT OF 5, WITH
GOOD AGREEMENT ON SYNOPTIC PATTERN AMONG DYNAMICAL MODELS, OFFSET BY WEAKER
ANOMALIES AND PROBABILITIES IN THE PRECIPITATION FORECAST.
FORECASTER: DANIEL BARANDIARAN
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 18.
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:
19841208 - 19941212 - 19901210 - 19651208 - 19931204
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:
19841208 - 19941212 - 19901210 - 19991202 - 19651208
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 27 - 31 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A N NRN CALIF A A
SRN CALIF A A IDAHO A B NEVADA A B
W MONTANA A B 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 B
N TEXAS N B S TEXAS N B W TEXAS N B
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS N B LOUISIANA B B WISCONSIN A B
ILLINOIS A B MISSISSIPPI N B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA N B 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 A NEW JERSEY A A W VIRGINIA A N
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A N S CAROLINA A B GEORGIA N B
FL PNHDL B B FL PENIN B A AK N SLOPE N N
AK ALEUTIAN B N AK WESTERN B N AK INT BSN A N
AK S INT N A AK SO COAST N A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 29, 2023 - JAN 04, 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A N NRN CALIF A A
SRN CALIF A A IDAHO A B NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A N ARIZONA A A COLORADO A N
NEW MEXICO A A N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A N OKLAHOMA N A
N TEXAS N A S TEXAS N A W TEXAS A A
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS N B LOUISIANA B A WISCONSIN A B
ILLINOIS A B MISSISSIPPI B N MICHIGAN A B
INDIANA N B OHIO N B KENTUCKY N B
TENNESSEE N B ALABAMA B B NEW YORK N B
VERMONT A B NEW HAMP A B MAINE A B
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 B B VIRGINIA B B
N CAROLINA B B S CAROLINA B B GEORGIA B N
FL PNHDL B N FL PENIN B A AK N SLOPE A N
AK ALEUTIAN B N AK WESTERN A N AK INT BSN A N
AK S INT A A AK SO COAST A A AK PNHDL A N
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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