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FXUS06 KWBC 222002
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST FRI DECEMBER 22 2023
6-10 DAY OUTLOOK FOR DEC 28, 2023 - JAN 01, 2024
TODAY’S GEFS, CMCE, AND ECMWF SOLUTIONS OF THE 500-HPA HEIGHT ANOMALY FIELD
DEPICT DEEP TROUGHING OVER THE NORTH PACIFIC AND BERING SEA, MODERATE NEGATIVE
HEIGHT ANOMALIES CENTERED OVER THE SOUTHEASTERN CONTIGUOUS U.S. (CONUS), AND
EXPANSIVE POSITIVE HEIGHT ANOMALIES COVERING APPROXIMATELY THE NORTHWESTERN
HALF OF THE CONUS, CANADA, AND EASTERN ALASKA. RELATIVE TO YESTERDAY, TODAY’S
MANUAL HEIGHT FORECAST PREDICTS A SLIGHTLY LESS AMPLIFIED TROUGH OVER THE NORTH
PACIFIC/BERING SEA, WITH THE GREATEST NEGATIVE HEIGHT DEPARTURES NEAR -150
METERS CENTERED FARTHER NORTHWEST TODAY OVER THE ALEUTIANS. THE EXPECTED
WEAKENING OF THIS TROUGH ALLOWS THE BROAD ANOMALOUS RIDGE OVER CANADA TO SPREAD
WESTWARD ACROSS EASTERN ALASKA, ACCOMPANIED BY RISING 500-HPA HEIGHTS. THE
TROUGHING CENTERED OVER THE SOUTHEAST IS PREDICTED TO BE SLIGHTLY STRONGER
TODAY IN THE MANUAL HEIGHT FORECAST RELATIVE TO YESTERDAY. ABOVE-NORMAL 500-HPA
HEIGHTS ARE FORECAST ACROSS HAWAII.
MID-LEVEL RIDGING AND/OR POSITIVE HEIGHT ANOMALIES FAVOR ABOVE-NORMAL
TEMPERATURES OVER MUCH OF THE NORTHERN AND WESTERN LOWER 48 STATES. THIS IS
CONSISTENT WITH REFORECAST TEMPERATURES FROM THE ENSEMBLE MEAN MODELS.
PROBABILITIES FAVORING ABOVE-NORMAL TEMPERATURES EXCEED 60% FOR PARTS OF THE
NORTHERN TIER STATES AND CENTRAL PORTIONS OF THE WEST COAST. OVER THE
SOUTHEASTERN QUARTER OF THE CONUS, NEGATIVE 500-HPA HEIGHT ANOMALIES AND
MID-LEVEL TROUGHING FAVOR BELOW-NORMAL TEMPERATURES, WITH PROBABILITIES
EXCEEDING 70% ACROSS SOUTHERN FLORIDA. THIS BROAD AREA OF FAVORED BELOW-NORMAL
TEMPERATURES IS SUPPORTED BY MANY OF TODAY’S DYNAMICAL AND STATISTICAL
TEMPERATURE TOOLS. AT HIGHER LATITUDES, THE PREDICTED WEAKENING OF THE NORTH
PACIFIC TROUGH AND WESTWARD EXPANSION OF THE VERY ANOMALOUS RIDGE OVER CANADA
LEADS TO SLIGHTLY ENHANCED BELOW NORMAL TEMPERATURE PROBABILITIES FOR ONLY FAR
WESTERN PORTIONS OF ALASKA, AND FAVORED ABOVE NORMAL TEMPERATURES FOR CENTRAL
AND EASTERN PORTIONS OF THE STATE. FOR HAWAII, FORECAST TOOLS FAVOR NEAR-NORMAL
TEMPERATURES FOR MOST OF THE ISLANDS EXCEPT THE BIG ISLAND, WHERE THERE IS A
SLIGHT TILT TOWARDS BELOW-NORMAL TEMPERATURES.
A BROAD RIDGE-TROUGH PATTERN PREDICTED OVER MUCH OF NORTH AMERICA FAVORS
WIDESPREAD DRIER NORTHWEST FLOW ALOFT, ACCOMPANIED BY MOSTLY BELOW-NORMAL
PRECIPITATION CHANCES. PROBABILITIES OF BELOW-NORMAL PRECIPITATION EXCEED 60%
FOR PORTIONS OF THE NORTHERN HIGH PLAINS. WITH DEEP TROUGHING UPSTREAM OVER THE
NORTH PACIFIC, ABOVE-NORMAL PRECIPITATION CHANCES ARE ELEVATED OVER MOST OF
CALIFORNIA AND PARTS OF WESTERN NEVADA, WITH PROBABILITIES NEAR 50% FOR COASTAL
AREAS OF NORTHERN AND CENTRAL CALIFORNIA. AFTER A RELATIVELY SHORT BREAK IN
CALIFORNIA’S RECENT WET PERIOD, MOST DYNAMICAL AND STATISTICAL GUIDANCE
FORECAST THE ENHANCED STORMINESS TO RESUME. SMALL-SCALE AREAS OF FAVORED
ABOVE-NORMAL PRECIPITATION ARE ALSO INDICATED ACROSS FAR SOUTHERN TEXAS AND
SOUTHERN FLORIDA. IN ALASKA, BROAD ONSHORE FLOW PROMOTES ELEVATED CHANCES OF
ABOVE-NORMAL PRECIPITATION FOR ABOUT THE SOUTHERN HALF OF THE STATE, INCLUDING
THE WESTERN SEWARD PENINSULA. NEAR-NORMAL PRECIPITATION IS FAVORED FOR MOST OF
THE NORTHERN HALF OF THE STATE. THE PRECIPITATION OUTLOOK FOR ALASKA IS
CONSISTENT WITH THE MAJORITY OF PRECIPITATION TOOLS. 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
GOOD AGREEMENT AMONG THE MID-LEVEL HEIGHT TOOLS, THOUGH OFFSET BY AN EXPECTED
PROGRESSIVE PATTERN AND RAPID INCREASE IN PRECIPITATION CHANCES OVER PARTS OF
THE SOUTHERN CONUS THROUGHOUT THE PERIOD.
8-14 DAY OUTLOOK FOR DEC 30, 2023 - JAN 05, 2024
THE WEEK-2 FORECAST PERIOD FEATURES CONTINUED WEAKENING OF THE NORTH
PACIFIC/BERING SEA MID-LEVEL TROUGH AND AN AMPLIFYING RIDGE OVER WESTERN CANADA
THAT EXTENDS WESTWARD ACROSS MOST OF ALASKA AND SOUTHWARD INTO THE NORTHWESTERN
AND NORTH-CENTRAL CONUS. THE TROUGH PREDICTED TO BE CENTERED OVER THE SOUTHEAST
DURING THE EARLIER 6-10 DAY PERIOD IS EXPECTED TO SHIFT EASTWARD OFF THE EAST
COAST. A CORRIDOR OF BELOW-NORMAL 500-HPA HEIGHTS IS FORECASTED ACROSS THE
SOUTHERN THIRD OF THE CONUS, WHICH CONNECTS THE NORTH PACIFIC TROUGH WITH THE
EAST COAST/WESTERN ATLANTIC TROUGH.
FOR THE CONUS, THE WEEK-2 TEMPERATURE OUTLOOK LOOKS VERY SIMILAR TO THE
TEMPERATURE OUTLOOK VALID FOR THE 6-10 DAY PERIOD, BASED ON REFORECAST
TEMPERATURE GUIDANCE FROM THE GEFS AND ECMWF ENSEMBLES, AND THE SHORT-TERM
BIAS-CORRECTED NAEFS TEMPERATURE FORECAST. THE MORE SIGNIFICANT CHANGES TO THE
WEEK-2 OUTLOOKS ARE INDICATED FOR ALASKA AND HAWAII, WHERE A RAPID EXPANSION OF
FAVORED ABOVE-NORMAL TEMPERATURES IS DEPICTED. IN SOUTH-CENTRAL AND
SOUTHEASTERN ALASKA, PROBABILITIES FAVORING ABOVE-NORMAL EXCEED 60%.
THE WEEK-2 PRECIPITATION OUTLOOK TILTS THE ODDS TOWARDS BELOW-NORMAL
PRECIPITATION OVER MUCH OF THE NORTHERN AND EASTERN CONUS, SUPPORTED BY A
MAJORITY OF PRECIPITATION TOOLS. IN CONTRAST, ABOVE-NORMAL PRECIPITATION IS
FAVORED FROM CALIFORNIA AND SOUTHERN OREGON EASTWARD TO THE CENTRAL AND
SOUTHERN PLAINS AND NEIGHBORING PORTIONS OF THE LOWER MISSISSIPPI VALLEY. THIS
IS CONSISTENT WITH A RENEWED SOUTHERN STREAM WITH EMBEDDED SHORT WAVE TROUGHS,
AND WITH GEFS AND ECMWF REFORECAST PRECIPITATION. SOME OF THIS SOUTHERN STREAM
ENERGY IS EXPECTED TO REACH THE FLORIDA PENINSULA LATER IN THE WEEK-2 PERIOD.
AT HIGHER LATITUDES, MEAN SURFACE LOW PRESSURE ANTICIPATED NEAR THE ALEUTIANS
FAVORS SOUTHERLY ONSHORE FLOW OVER MOST OF THE SOUTHERN HALF OF ALASKA. THIS
PROMOTES INCREASED CHANCES OF ABOVE-NORMAL PRECIPITATION. FOR THE NORTHERN HALF
OF THE STATE, ODDS FAVOR NEAR- TO BELOW-NORMAL PRECIPITATION, ASSOCIATED WITH
THE FORECAST OF RISING 500-HPA HEIGHTS AND INCREASED MID-LEVEL RIDGING. THE
ERF-CON TOOL INDICATES NEAR-NORMAL PRECIPITATION FOR MOST OF THE HAWAIIAN
ISLANDS, EXCEPT FOR THE BIG ISLAND WHERE BELOW-NORMAL PRECIPITATION IS FAVORED.
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, WITH
GOOD AGREEMENT ON THE 7-DAY AVERAGE HEIGHT FORECASTS, OFFSET BY A VERY
PROGRESSIVE AND EVOLVING PATTERN, ESPECIALLY OVER THE SOUTHERN STATES.
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
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:
19931204 - 19991202 - 19941213 - 19911229 - 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:
19991202 - 19911230 - 19911225 - 19931203 - 19941213
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 28, 2023 - JAN 01, 2024
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 N
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 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 A B
ILLINOIS A B MISSISSIPPI B B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY N B
TENNESSEE B B ALABAMA B 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 N B
MARYLAND A B DELAWARE N B VIRGINIA N B
N CAROLINA B B S CAROLINA B B GEORGIA B B
FL PNHDL B B FL PENIN B N 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 30, 2023 - JAN 05, 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 N
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO N A N DAKOTA A B S DAKOTA A B
NEBRASKA A A KANSAS N A OKLAHOMA N A
N TEXAS N A S TEXAS B A W TEXAS N A
MINNESOTA A B IOWA A B MISSOURI N B
ARKANSAS N N LOUISIANA B A WISCONSIN A B
ILLINOIS N B MISSISSIPPI B N MICHIGAN A B
INDIANA N B OHIO N B KENTUCKY N B
TENNESSEE B 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 N GEORGIA B N
FL PNHDL B N FL PENIN B A AK N SLOPE A B
AK ALEUTIAN A A AK WESTERN A A 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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