932
FXUS06 KWBC 132002
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 13 2023
6-10 DAY OUTLOOK FOR DEC 19 - 23 2023
HE 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 GREAT LAKES REGION. A WEAK AREA OF
NEGATIVE 500-HPA HEIGHT ANOMALIES IS FORECAST EAST OF FLORIDA AS A SHORTWAVE
TROUGH PROGRESSES ALONG THE GULF COAST. A STRONGER AREA OF NEGATIVE 500-HPA
HEIGHT ANOMALIES IS FORECAST NEAR THE WEST COAST. THE GEFS AND ECMWF ARE COMING
INTO BETTER AGREEMENT WITH A MORE CUT-OFF LOW DEVELOPING EARLY IN THE PERIOD
BEFORE A STRONGER FULL LATITUDE TROUGH RELOADS STRETCHING BACK THROUGH ALASKA.
IN ALASKA, STRONG NEGATIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST ACROSS MUCH OF
THE STATE CENTERED ACROSS THE BERING SEA BRINGING SOUTHERLY FLOW INTO EASTERN
ALASKA. IN HAWAII, NEAR-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 WHERE DAILY TEMPERATURES ARE LIKELY TO
AVERAGE MORE THAN 10 DEG. F ABOVE NORMAL. AN EXCEPTION OF THE FAVORED
ABOVE-NORMAL TEMPERATURES IS FOR PARTS OF THE SOUTHEAST AND FLORIDA WHERE A
SHORTWAVE TROUGH IS FORECAST TO PROVIDE A SLIGHT COOLING EFFECT. NEAR-NORMAL
TEMPERATURES ARE FAVORED ACROSS THIS AREA WITH A SLIGHT TILT TOWARDS
BELOW-NORMAL ACROSS THE SOUTHERN FLORIDA PENINSULA. ABOVE-NORMAL TEMPERATURES
ARE FAVORED ACROSS EASTERN ALASKA AS SOUTHERLY FLOW CONTINUES TO BRING WARM
MOIST AIR FROM THE PACIFIC INTO THE REGION WHILE NEAR-NORMAL IS FAVORED ACROSS
WESTERN ALASKA CLOSER TO THE TROUGH AXIS. IN HAWAII, ABOVE-NORMAL IS FAVORED
FOR MOST OF THE ISLANDS AS THE MODEL CONSOLIDATION TOOLS SHIFTED TOWARDS A
WARMER SOLUTION RELATIVE TO PREVIOUS FORECASTS.
ABOVE-NORMAL PRECIPITATION IS FAVORED FROM CALIFORNIA EAST TO THE HIGH PLAINS
AS MOIST AIR FROM THE PACIFIC CONTINUES TO FLOW INTO THE WESTERN CONUS. MODEL
SOLUTIONS ARE IN GOOD AGREEMENT THAT AN AMPLIFIED MID-LEVEL TROUGH SHIFTS
EASTWARD TOWARDS THE WEST COAST DURING THE 6 TO 10 DAY PERIOD. REFORECAST TOOLS
FROM THE GEFS AND ECMWF STRONGLY SUPPORT ABOVE-NORMAL PRECIPITATION ACROSS THE
CENTRAL CALIFORNIA COAST WITH ABOVE-NORMAL PRECIPITATION BEING FAVORED FURTHER
EAST, INTO THE PLAINS, RELATIVE TO YESTERDAY’S FORECAST AS ENHANCED PACIFIC
MOISTURE PUSHES FURTHER INTO NORTH AMERICA. BELOW-NORMAL PRECIPITATION REMAINS
FAVORED ACROSS THE NORTHERN TIER IN THE WESTERN CONUS AS THE PRIMARY MOISTURE
FLOW IS FORECAST TO REMAIN FURTHER SOUTH. ACROSS THE EAST, BELOW-NORMAL
PRECIPITATION REMAINS FAVORED FOR AREAS ALONG AND EAST OF THE MISSISSIPPI RIVER
AS STRONG MID-LEVEL RIDGING AND SURFACE HIGH PRESSURE LIMIT CHANCES FOR
PRECIPITATION. IN ALASKA, ABOVE-NORMAL PRECIPITATION IS FAVORED FOR SOUTHERN
PARTS OF THE STATE AS SOUTHERLY FLOW AROUND A MID-LEVEL TROUGH AND SURFACE
LOW-PRESSURE BRING INCREASED MOISTURE INTO THE STATE. MEANWHILE, NEAR-NORMAL IS
FAVORED ACROSS THE NORTH SLOPE OF ALASKA. NEAR-NORMAL PRECIPITATION IS FAVORED
ACROSS THE HAWAIIAN ISLANDS.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 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 20%
OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: FORECAST CONFIDENCE:
ABOVE-AVERAGE, 4 OUT 5, GOOD AGREEMENT AMONG THE MODEL TOOLS IS OFFSET SLIGHTLY
BY DISAGREEMENTS WITH THE STRENGTH OF THE TROUGH ALONG THE WEST COAST.
8-14 DAY OUTLOOK FOR DEC 21 - 27 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 REMAIN ACROSS THE EASTERN TWO-THIRDS OF THE CONUS WITH
THE PATTERN PROGRESSING NORTHEASTWARD RELATIVE TO YESTERDAY. NEAR-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 HEIGHTS ARE FORECAST TO DEEPEN AND EXPAND ACROSS MORE OF THE
WEST COAST WITH A FULL LATITUDE TROUGH DEVELOPING. STRONG NEGATIVE 500-HPA
HEIGHT ANOMALIES CONTINUE TO BE FORECAST ACROSS ALASKA. 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 STRONGEST CHANCES FOR ABOVE-NORMAL TEMPERATURES,
EXCEEDING 80%, IS ACROSS THE NORTHERN AND CENTRAL PLAINS, UPPER AND
MIDDLE-MISSISSIPPI VALLEY, AND THE GREAT LAKES. THE REMNANTS OF A SHORTWAVE
TROUGH EARLY AND THE POTENTIAL DEVELOPMENT OF A SECONDARY SYSTEM LATER IN THE
PERIOD BRING CHANCES FOR NEAR-NORMAL TEMPERATURES TO SOUTHERN FLORIDA. IN
PARTS OF CALIFORNIA, THERE ARE REDUCED CHANCES FOR ABOVE-NORMAL TEMPERATURES,
BUT STILL FAVORED, WHERE ABOVE-NORMAL PRECIPITATION MAY BRING MORE CLOUDS AND
REDUCED DAYTIME TEMPERATURES. IN ALASKA, SOUTHERLY FLOW IS FORECAST FOR EASTERN
PORTIONS OF THE STATE BRINGING ABOVE-NORMAL TEMPERATURES CHANCES. SOME NEAR TO
BELOW-NORMAL IS FAVORED FOR PARTS OF WESTERN ALASKA AND THE ALEUTIAN ISLANDS
NEAR AND BEHIND THE TROUGH AXIS. MEANWHILE, ABOVE-NORMAL TEMPERATURES ARE
FAVORED FOR HAWAII AS TOOLS INDICATE A CONTINUED WARMING TREND RELATIVE TO
PREVIOUS FORECASTS.
A SHORTWAVE TROUGH 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 ABOVE-NORMAL PRECIPITATION PROBABILITIES ACROSS
CALIFORNIA ALONG WITH THE GREAT BASIN AND SOUTHWEST INTO THE PLAINS. IN THE
CLIMATOLOGICALLY WETTER AREAS OF THE PACIFIC NORTHWEST, NEAR-NORMAL
PRECIPITATION IS FORECAST. ABOVE-NORMAL PRECIPITATION IS SLIGHTLY FAVORED
ACROSS THE CENTRAL AND SOUTHERN PLAINS INTO THE MIDDLE AND LOWER-MISSISSIPPI
VALLEY AS ENSEMBLE MEANS SHOW AN INCREASING WET SIGNAL LATE IN WEEK-2,
DOWNSTREAM OF THE AMPLIFIED TROUGH NEAR THE WEST COAST. A BROAD RIDGE IS
FORECAST TO BE CENTERED NEAR THE SOUTHERN HUDSON BAY. THIS BRINGS CHANCES FOR
BELOW-NORMAL PRECIPITATION ACROSS PARTS OF THE NORTHERN PLAINS AND GREAT LAKES
AND NORTHEAST. NEAR-NORMAL PRECIPITATION IS FAVORED FOR PARTS OF THE SOUTHEAST
AS MODELS CONTINUE TO HINT AT A CHANCE FOR A SOUTHERN STREAM SHORTWAVE TROUGH
TO PROGRESS THROUGH THE REGION LATE IN WEEK-2. ABOVE-NORMAL PRECIPITATION
REMAINS FAVORED FOR MUCH OF ALASKA WITH THE STRONGEST CHANCES IN SOUTHEAST
ALASKA. NEAR-NORMAL IS FAVORED ACROSS MOST OF WESTERN ALASKA AND THE NORTH
SLOPE. BELOW-NORMAL PRECIPITATION IS FAVORED IN HAWAII IN AGREEMENT WITH
CONSOLIDATION TOOLS.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 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 20%
OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: 3 OUT 5, AVERAGE, GOOD AGREEMENT
AMONG THE MODEL TOOLS IS OFFSET BY A FAIRLY PROGRESSIVE PATTERN THAT PROVIDES A
MORE CHALLENGING ENVIRONMENT TO FORECAST.
FORECASTER: RYAN BOLT
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:
19571208 - 19911123 - 19991214 - 19901205 - 19641207
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:
19901205 - 19591207 - 19911122 - 19631127 - 20051122
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 19 - 23 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 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 N
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A N S TEXAS A N W TEXAS A A
MINNESOTA A B IOWA A N MISSOURI A B
ARKANSAS A B LOUISIANA A B WISCONSIN A B
ILLINOIS A B MISSISSIPPI A B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A 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 A B W VIRGINIA A B
MARYLAND A B DELAWARE A B VIRGINIA A B
N CAROLINA A B S CAROLINA A B GEORGIA N B
FL PNHDL N B FL PENIN N B AK N SLOPE A N
AK ALEUTIAN N A AK WESTERN N A AK INT BSN A N
AK S INT A A AK SO COAST A A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 21 - 27 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 N 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 N IOWA A A MISSOURI A A
ARKANSAS A N LOUISIANA A N WISCONSIN A N
ILLINOIS A N MISSISSIPPI A N MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A N 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 A N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN N 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 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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