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FXUS06 KWBC 202003
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST WED DECEMBER 20 2023
6-10 DAY OUTLOOK FOR DEC 26 - 30 2023
TODAY’S GEFS, CMCE, AND ECMWF SOLUTIONS OF THE 500-HPA 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
MOUNTAIN WEST AND GREAT PLAINS.
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. 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 FAIRLY WET PATTERN FOR THE COASTS. IN THE EAST PROBABILITIES
FOR ABOVE-NORMAL PRECIPITATION ARE HIGHEST FOR PORTIONS OF FLORIDA, EASTERN
NORTH CAROLINA, AND SOUTHEASTERN VIRGINIA (>50%), AND ENHANCED PROBABILITIES
EXTEND UP THE EAST COAST AND OVER THE APPALACHIANS. ABOVE-NORMAL PRECIPITATION
IS ALSO 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 MISSISSIPPI RIVER, WITH HIGHER ODDS FOR THE NORTHERN
PLAINS, ROCKY MOUNTAINS, AND MUCH OF CENTRAL AND NORTHERN TEXAS. SOUTHERLY FLOW
OFF THE NORTH PACIFIC TILTS MOST OF ALASKA TOWARDS ABOVE-NORMAL
PRECIPITATION,WHILE NEAR-NORMAL PRECIPITATION IS MOST LIKELY FOR THE
SOUTHWESTERN PORTION 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 38% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 37% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 25% 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 28, 2023 - JAN 03, 2024
THE WEEK-2 FORECAST PERIOD FEATURES A SIMILAR SYNOPTIC PICTURE TO WHAT IS SEEN
IN THE 6-10 DAY PERIOD. 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 NORTHERN PLAINS, 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.
THE SYNOPTIC FLOW OVER ALASKA IS MOSTLY UNCHANGED FROM THE 6-10 DAY PERIOD, SO
THE WEST-EAST, BELOW-ABOVE NORMAL PATTERN FOR TEMPERATURES CONTINUES INTO
WEEK-2. 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 SLIGHTLY EASTWARD 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 NEARLY TO
THE COAST, WITH WIDESPREAD COVERAGE FOR MOST OF THE NORTHERN CONUS, THE
MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, AND SOUTHEAST U.S. ONLY THE FLORIDA
PENINSULA 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
PARTS OF HAWAII.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 37% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 38% 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 LARGE
SHIFTS IN PRECIPITATION GUIDANCE RELATIVE TO YESTERDAY.
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
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:
19841208 - 19901210 - 19941212 - 19571214 - 19651208
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:
19901210 - 19571214 - 19841207 - 19911212 - 19651206
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 26 - 30 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 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 N B N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A B OKLAHOMA N B
N TEXAS N B S TEXAS B 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 N MICHIGAN A B
INDIANA A N OHIO A A KENTUCKY A N
TENNESSEE A N ALABAMA A N 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 A A GEORGIA A A
FL PNHDL N A FL PENIN N A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B N AK INT BSN A A
AK S INT N A AK SO COAST B A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 28, 2023 - JAN 03, 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 B
N TEXAS N N S TEXAS B A W TEXAS N A
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS N B LOUISIANA B B WISCONSIN A B
ILLINOIS A B MISSISSIPPI B B MICHIGAN A B
INDIANA A B OHIO N B KENTUCKY N B
TENNESSEE N B ALABAMA B B NEW YORK A B
VERMONT A B NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS A N
PENN A B NEW JERSEY N N W VIRGINIA N B
MARYLAND N B DELAWARE N N VIRGINIA N B
N CAROLINA N B S CAROLINA B B GEORGIA B B
FL PNHDL B N FL PENIN B A AK N SLOPE A N
AK ALEUTIAN B N AK WESTERN N 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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