581
FXUS06 KWBC 142039
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 14 2023
6-10 DAY OUTLOOK FOR DEC 20 - 24 2023
THE FORECASTED MID-LEVEL HEIGHT PATTERN CONTINUES TO LOOK SIMILAR TO PREVIOUS
FORECASTS. POSITIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST ACROSS MUCH OF THE
CONTIGUOUS U.S. (CONUS) CENTERED ACROSS THE UPPER GREAT LAKES REGION. A WEAK
AREA OF NEGATIVE 500-HPA HEIGHT ANOMALIES IS FORECAST EAST OF FLORIDA AS A
SHORTWAVE TROUGH PROGRESSES THROUGH THE REGION. A STRONGER AREA OF NEGATIVE
500-HPA HEIGHT ANOMALIES IS FORECAST NEAR THE SOUTHERN HALF OF THE WEST COAST.
THE GEFS AND ECMWF ARE IN REASONABLE AGREEMENT PREDICTING A CLOSED-OFF LOW
BRIEFLY DEVELOPING EARLY IN THE PERIOD BEFORE A STRONGER FULL LATITUDE TROUGH
RELOADS STRETCHING BACK THROUGH WESTERN ALASKA. WELL BELOW-NORMAL 500-HPA
HEIGHTS ARE FORECAST ACROSS THE BERING SEA AND MUCH OF ALASKA. MOIST SOUTHERLY
FLOW IS FORECAST ACROSS EASTERN ALASKA AHEAD OF THE DEEP TROUGH PREDICTED OVER
THE EASTERN BERING SEA. IN HAWAII, NEAR TO SLIGHTLY ABOVE-NORMAL 500-HPA
HEIGHTS ARE FAVORED.
THE PERSISTENT PACIFIC FLOW ACROSS THE CONUS LEADS TO A CONTINUATION OF MILD
TEMPERATURES FOR MUCH OF THE CONUS. THE LARGEST PROBABILITIES, MORE THAN 80%,
FOR ABOVE-NORMAL TEMPERATURES ARE FORECAST ACROSS THE NORTHERN AND CENTRAL
PLAINS AND UPPER MISSISSIPPI VALLEY. AN EXCEPTION TO THE FAVORED ABOVE-NORMAL
TEMPERATURES IS FROM THE EASTERN HALF OF THE GULF COAST REGION (INCLUDING
FLORIDA) NORTHEASTWARD OVER THE EAST COAST STATES TO CENTRAL NEW ENGLAND, WHERE
NEAR TO BELOW-NORMAL TEMPERATURES ARE FAVORED. THIS IS ASSOCIATED WITH THE
EXPECTED PASSAGE OF A SHORTWAVE TROUGH. ABOVE-NORMAL TEMPERATURES ARE FAVORED
ACROSS CENTRAL AND EASTERN ALASKA AS SOUTHERLY FLOW CONTINUES TO BRING WARM
MOIST AIR FROM THE PACIFIC INTO THE REGION WHILE NEAR-NORMAL TEMPERATURES ARE
FAVORED ACROSS WESTERN ALASKA, CLOSER TO THE TROUGH AXIS. IN HAWAII,
ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR THE ENTIRE ARCHIPELAGO, BASED ON THE
TEMPERATURE CONSOLIDATION TOOL.
ABOVE-NORMAL PRECIPITATION IS FAVORED FROM CALIFORNIA EAST TO THE CENTRAL AND
SOUTHERN PLAINS AND ADJACENT PARTS OF THE MISSISSIPPI VALLEY, AS MOIST AIR FROM
THE PACIFIC CONTINUES TO FLOW INTO THE WESTERN CONUS. PROBABILITIES FAVORING
ABOVE-NORMAL PRECIPITATION EXCEED 60% FROM SOUTHERN CALIFORNIA EASTWARD TO
SOUTHWESTERN NEW MEXICO. THIS IS BASED ON GOOD AGREEMENT AMONG THE GEFS, ECMWF,
AND CANADIAN REFORECAST PRECIPITATION TOOLS DURING THE 6 TO 10 DAY PERIOD.
BELOW-NORMAL PRECIPITATION CHANCES ARE ENHANCED OVER THE NORTHERN CONUS, WELL
REMOVED FROM THE PRIMARY STORM TRACK. ACROSS THE EAST, BELOW-NORMAL
PRECIPITATION CHANCES ARE ALSO INCREASED DUE TO MID-LEVEL RIDGING, MOSTLY
ABOVE-NORMAL 500-HPA HEIGHTS, AND INCREASED SUBSIDENCE OF AIR IN THE WAKE OF
THE SOUTHERN STREAM TROUGH PREDICTED JUST EAST OF FLORIDA. IN ALASKA,
ABOVE-NORMAL PRECIPITATION IS FAVORED FOR MOST OF THE STATE AS SOUTHERLY FLOW
AROUND A MID-LEVEL TROUGH AND SURFACE LOW-PRESSURE BRING INCREASED MOISTURE
INTO THE STATE. ODDS FAVORING ABOVE-NORMAL PRECIPITATION EXCEED 50% OVER THE
COPPER RIVER BASIN AND SOUTHEAST ALASKA. ACROSS THE HAWAIIAN ISLANDS,
ABOVE-NORMAL PRECIPITATION IS FAVORED DUE TO AN ACTIVE AREA OF LOW PRESSURE
FORECAST TO PASS TO THE SOUTH OF THE ISLAND CHAIN.
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, DUE TO
GOOD AGREEMENT AMONG THE MID-LEVEL HEIGHT FORECASTS, OFFSET BY MINOR
DIFFERENCES AMONG THE SURFACE TEMPERATURE AND PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR DEC 22 - 28 2023
AS WITH THE 6 TO 10 DAY PERIOD, THE FORECASTED 500-HPA HEIGHT PATTERN REMAINS
IN GOOD AGREEMENT WITH THE EARLIER PERIOD AND YESTERDAY’S FORECAST. POSITIVE
500-HPA HEIGHT ANOMALIES CONTINUE OVER ALL BUT FAR WESTERN AND FAR SOUTHERN
PORTIONS OF THE CONUS WITH THE PATTERN PROGRESSING NORTHEASTWARD RELATIVE TO
YESTERDAY. NEAR- TO SLIGHTLY BELOW-NORMAL 500-HPA HEIGHTS ARE NOW FAVORED
ACROSS THE SOUTHERN TIER OF THE CONUS AS A SHORTWAVE TROUGH MAY EJECT OUT OF
THE WEST DURING THE MIDDLE OF THE PERIOD. NEGATIVE 500-HPA HEIGHT ANOMALIES ARE
FORECAST TO DEEPEN OVER THE GULF OF ALASKA AND EXTEND SOUTHEASTWARD, WITH THE
GEFS BRINGING MORE ENERGY ACROSS THE WEST COAST STATES THAN THE ECMWF ENSEMBLE.
LARGE NEGATIVE 500-HPA HEIGHT ANOMALIES CONTINUE TO BE FORECAST ACROSS ALASKA,
ESPECIALLY THE SOUTHWESTERN PORTION OF THE STATE. POSITIVE 500-HPA HEIGHT
ANOMALIES ARE FORECAST ACROSS THE HAWAIIAN ISLANDS.
ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR NEARLY THE ENTIRE UNITED STATES FOR
THE WEEK-2 PERIOD. THE GREATEST CHANCES FOR ABOVE-NORMAL TEMPERATURES,
EXCEEDING 80%, IS OVER THE GENERAL VICINITY OF THE UPPER MISSISSIPPI VALLEY.
THIS IS WELL SUPPORTED BY THE REFORECAST TEMPERATURE TOOLS, THE
AUTO-TEMPERATURE TOOL, AND THE SHORT-TERM BIAS-CORRECTED NAEFS. NEAR-NORMAL
TEMPERATURES ARE FAVORED OVER SOUTHERN FLORIDA, CONSISTENT WITH PREDICTED
NEAR-NORMAL 500-HPA HEIGHTS IN THAT REGION, AND A MAJORITY OF THE SURFACE
TEMPERATURE TOOLS. IN ALASKA, SOUTHERLY FLOW IS FORECAST FOR CENTRAL AND
EASTERN PORTIONS OF THE STATE BRINGING ENHANCED ABOVE-NORMAL TEMPERATURES
CHANCES. CLOSER TO THE MEAN TROUGH AXIS OVER THE BERING SEA, NEAR-NORMAL
TEMPERATURES ARE FAVORED ACROSS WESTERN ALASKA, WITH A RELATIVELY SMALL AREA OF
FAVORED BELOW-NORMAL TEMPERATURES DEPICTED OVER THE ALEUTIANS. MEANWHILE,
ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR HAWAII BASED ON THE TEMPERATURE
CONSOLIDATION TOOL.
SHORTWAVE ENERGY MOVING INLAND FROM THE EASTERN PACIFIC EARLY IN WEEK-2
FOLLOWED BY THE DEVELOPMENT OF A FULL LATITUDE TROUGH OVER THE NORTHEASTERN
PACIFIC LEADS TO INCREASED CHANCES OF ABOVE-NORMAL PRECIPITATION FROM
CALIFORNIA AND SOUTHERN OREGON EASTWARD ACROSS APPROXIMATELY THE SOUTHERN
HALVES OF THE INTERMOUNTAIN WEST AND ROCKIES, MOST OF THE GREAT PLAINS AND
MISSISSIPPI VALLEY, THE LOWER OHIO AND TENNESSEE VALLEYS, THE EASTERN GULF
COAST REGION, AND THE ATLANTIC COAST STATES FROM FLORIDA TO SOUTHEASTERN
VIRGINIA. IN ADDITION TO PASSING SHORTWAVE TROUGHS AT 500-HPA, SURFACE HIGH
PRESSURE LOCATED OVER THE SOUTHEAST WILL HELP CHANNEL LOW-LEVEL GULF MOISTURE
INTO THE CENTRAL PART OF THE CONUS. ODDS FAVORING ABOVE-NORMAL PRECIPITATION
EXCEED 50% FROM SOUTHERN CALIFORNIA EASTWARD ACROSS THE SOUTHWEST TO THE TEXAS
RIO GRANDE VALLEY. BELOW-NORMAL PRECIPITATION CHANCES ARE ELEVATED ACROSS THE
NORTHERN TIER FROM THE NORTHERN ROCKIES TO NORTHERN MINNESOTA, CONTINUING
EASTWARD OVER MOST OF THE GREAT LAKES, NEW YORK STATE, AND NEW ENGLAND.
ABOVE-NORMAL PRECIPITATION REMAINS FAVORED FOR MUCH OF ALASKA WITH THE GREATEST
CHANCES IN SOUTH-CENTRAL AND SOUTHEAST ALASKA. THE TEMPERATURE CONSOLIDATION
TOOL FAVORS BELOW-NORMAL PRECIPITATION FOR KAUAI AND OAHU, AND NEAR-NORMAL
PRECIPITATION ELSEWHERE IN HAWAII.
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: NEAR AVERAGE, 3 OUT OF 5 DUE TO
GENERALLY GOOD AGREEMENT AMONG THE 500-HPA HEIGHT FORECASTS, OFFSET BY A FAIRLY
PROGRESSIVE PATTERN THAT PROVIDES A MORE CHALLENGING ENVIRONMENT TO FORECAST.
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:
19591219 - 19581228 - 19541220 - 20061228 - 19591214
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:
19591217 - 19971213 - 20031130 - 19651203 - 19541221
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 20 - 24 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B 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 A ARIZONA A A COLORADO A A
NEW MEXICO A A N DAKOTA A B S DAKOTA A N
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA A B IOWA A N MISSOURI A A
ARKANSAS A N LOUISIANA A N WISCONSIN A B
ILLINOIS A B MISSISSIPPI A N 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 N B CONN N B RHODE IS N B
PENN N B NEW JERSEY N B W VIRGINIA N B
MARYLAND N B DELAWARE N B VIRGINIA N B
N CAROLINA N B S CAROLINA B B GEORGIA N B
FL PNHDL B B FL PENIN B N AK N SLOPE N A
AK ALEUTIAN N A AK WESTERN N 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 DEC 22 - 28 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A N NRN CALIF A A
SRN CALIF A A IDAHO A N NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A N
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A A N DAKOTA A B S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA A N IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN A N
ILLINOIS A A MISSISSIPPI A A MICHIGAN A B
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA A A 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 N W VIRGINIA A N
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN N A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN N N 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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