636
FXUS06 KWBC 062003
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 06 2023
6-10 DAY OUTLOOK FOR DEC 12 - 16 2023
THE GEFS, ECMWF, AND CANADIAN ENSEMBLE MEANS ARE IN GOOD AGREEMENT DEPICTING A
BROAD 500-HPA RIDGE OVER THE NORTHERN TWO-THIRDS OF THE WESTERN AND CENTRAL
CONTIGUOUS U.S. (CONUS). THIS BROAD RIDGE WITH POSITIVE 500-HPA HEIGHT
ANOMALIES ALONG WITH STRONG WEST-TO-EAST SURFACE FLOW ACROSS CANADA FAVORS
ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE WEST, GREAT PLAINS, AND UPPER
MISSISSIPPI VALLEY. MODEL SOLUTIONS HAVE A LONGWAVE TROUGH NEAR THE EAST COAST
AND ALSO A SHORTWAVE TROUGH TRACKING EASTWARD ACROSS THE SOUTHERN TIER OF THE
CONUS. THESE TWO FEATURES ARE EXPECTED TO PROMOTE 5-DAY TEMPERATURES CLOSER TO
AVERAGE OR BELOW-NORMAL ACROSS SOUTHEASTERN NEW MEXICO, TEXAS, AND MUCH OF THE
EASTERN CONUS. THE TEMPERATURE TOOLS GENERALLY TILT TOWARDS ABOVE NORMAL FOR
SOUTH FLORIDA AND PARTS OF NORTHERN NEW ENGLAND.
EXPANSIVE SURFACE HIGH PRESSURE FAVORS BELOW-NORMAL PRECIPITATION THROUGHOUT
MUCH OF THE CONUS. HOWEVER, A SOUTHERN STREAM SHORTWAVE LEADS TO INCREASED
ABOVE-NORMAL PRECIPITATION PROBABILITIES ACROSS THE SOUTHERN GREAT PLAINS, RIO
GRANDE VALLEY, AND PARTS OF THE SOUTHEAST. ALTHOUGH THE REFORECAST TOOLS HAVE A
DRY SIGNAL FOR THE MID-ATLANTIC, THERE IS MORE UNCERTAINTY IN THE 6-10 DAY
PRECIPITATION OUTLOOK ACROSS THIS REGION. RECENT DETERMINISTIC GFS AND ECMWF
MODEL RUNS AND A FEW OF THEIR ENSEMBLE MEMBERS FAVOR SURFACE LOW DEVELOPMENT
NEAR THE MID-ATLANTIC BY DECEMBER 15 OR 16. GIVEN THIS POTENTIAL LOW PRESSURE
SYSTEM, BELOW-NORMAL PRECIPITATION PROBABILITIES ARE LIMITED FOR THE
MID-ATLANTIC. SINCE THE ENSEMBLE MEANS MAINTAIN A LONGWAVE RIDGE NEAR THE WEST
COAST THROUGH DAY 9, NEAR TO BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS
CALIFORNIA AND THE PACIFIC NORTHWEST.
MODEL SOLUTIONS ARE IN EXCELLENT AGREEMENT ON AN AMPLIFIED 500-HPA TROUGH WITH
ITS AXIS CENTERED OVER WESTERN MAINLAND ALASKA AND THE ALASKA PENINSULA. THIS
LONGWAVE TROUGH FAVORS BELOW (ABOVE) NORMAL TEMPERATURES ACROSS NORTHERN AND
WESTERN MAINLAND ALASKA, ALASKA PENINSULA, AND THE ALEUTIANS (SOUTHEASTERN
ALASKA). ENHANCED ABOVE-NORMAL PRECIPITATION PROBABILITIES FORECAST FOR
SOUTHEASTERN ALASKA ARE SUPPORTED BY THE LONGWAVE PATTERN, ENHANCED ONSHORE
FLOW, AND THE REFORECAST TOOLS.
THE 6-10 DAY TEMPERATURE AND PRECIPITATION OUTLOOKS FOR HAWAII ARE BASED ON THE
CONSOLIDATION TOOL, WHICH FAVORS ABOVE-NORMAL TEMPERATURES AND NEAR NORMAL
PRECIPITATION THROUGHOUT HAWAII.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 35% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 35% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 30% 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 ON THE LONGWAVE PATTERN ALONG WITH THE TEMPERATURE AND
PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR DEC 14 - 20 2023
THE GEFS, ECMWF, AND CANADIAN ENSEMBLE MEANS MAINTAIN THE BROAD RIDGE WITH
POSITIVE 500-HPA HEIGHT ANOMALIES ACROSS THE NORTHERN TWO-THIRDS OF THE CONUS,
WHILE THE SOUTHERN STREAM IS ACTIVE WITH MULTIPLE SHORTWAVE TROUGHS. THIS
PERSISTENT PATTERN LEADS TO CONTINUED HIGH FORECAST CONFIDENCE FOR MILD
DECEMBER TEMPERATURES. THE LARGEST PROBABILITIES (MORE THAN 70 PERCENT) OF
ABOVE NORMAL TEMPERATURES ARE FORECAST ACROSS THE NORTHERN GREAT PLAINS. THE
MORE ACTIVE SOUTHERN STREAM ALONG WITH SMALL NEGATIVE 500-HPA HEIGHT ANOMALIES
FAVORS NEAR TO BELOW-NORMAL TEMPERATURES ACROSS CENTRAL TO SOUTHERN TEXAS, THE
LOWER MISSISSIPPI VALLEY, SOUTHEAST, AND MID-ATLANTIC.
MULTIPLE SHORTWAVE TROUGHS LEAD TO INCREASED ABOVE-NORMAL PRECIPITATION
PROBABILITIES ACROSS THE SOUTHERN GREAT PLAINS, GULF COAST, AND PARTS OF THE
SOUTHEAST. BASED ON GOOD MODEL CONTINUITY AND THE ECMWF REFORECAST TOOL,
FORECAST CONFIDENCE FOR ABOVE-NORMAL PRECIPITATION IS HIGHEST ACROSS SOUTH
FLORIDA. TO THE NORTH OF THE PREDICTED STORM TRACK, 7-DAY MEAN SURFACE HIGH
PRESSURE FAVORS BELOW-NORMAL PRECIPITATION ACROSS THE NORTHEAST, MIDWEST, AND
NORTHERN TO CENTRAL GREAT PLAINS. THERE REMAINS LOWER FORECAST CONFIDENCE IN
THE PRECIPITATION OUTLOOK FOR THE MID-ATLANTIC DUE TO THE POTENTIAL FOR LOW
PRESSURE DEVELOPMENT NEAR THE EAST COAST, BUT THE TOOLS ARE TILTING ON THE
DRIER SIDE FROM THE MID-ATLANTIC NORTHWARD. COMPARED TO YESTERDAY, THE
REFORECAST TOOLS ARE WEAKER WITH THE WET SIGNAL ACROSS CALIFORNIA AND
ABOVE-NORMAL PRECIPITATION IS ONLY SLIGHTLY FAVORED CLOSER TO THE COAST. THE
TOOLS HAVE ALSO TRENDED DRIER FOR INLAND AREAS OF THE WEST.
DOWNSTREAM OF THE TROUGH AXIS, ABOVE-NORMAL PRECIPITATION IS FAVORED FOR
EASTERN ALASKA WITH NEAR TO BELOW-NORMAL PRECIPITATION MORE LIKELY FOR THE
REMAINDER OF THE STATE. CONSISTENT WITH THE 500-HPA AND SURFACE PATTERNS ALONG
WITH GOOD MODEL CONSISTENCY, BELOW-NORMAL TEMPERATURES ARE LIKELY FOR MUCH OF
ALASKA EXCEPT TO THE SOUTH OF YAKUTAT.
THE WEEK-2 TEMPERATURE OUTLOOK FOR HAWAII IS BASED ON THE CONSOLIDATION TOOL
AND FAVORS WARMER THAN NORMAL CONDITIONS AND NEAR NORMAL PRECIPITATION
THROUGHOUT THE STATE.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 35% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 35% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 30% 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, DUE TO
GOOD AGREEMENT AND CONSISTENCY AMONG THE TEMPERATURE AND PRECIPITATION TOOLS.
FORECASTER: BRAD PUGH
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:
19811203 - 19601119 - 20031214 - 19871203 - 20011219
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:
19651130 - 20031216 - 20071115 - 20001125 - 19811217
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 12 - 16 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N B OREGON A B NRN CALIF A B
SRN CALIF A B IDAHO N 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 A A
N TEXAS N A S TEXAS N A W TEXAS N A
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS N B LOUISIANA N B WISCONSIN A B
ILLINOIS A B MISSISSIPPI N B MICHIGAN N B
INDIANA N B OHIO N B KENTUCKY N B
TENNESSEE N B ALABAMA N B NEW YORK N B
VERMONT N B NEW HAMP N 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 N B GEORGIA N B
FL PNHDL B A FL PENIN A A AK N SLOPE B A
AK ALEUTIAN B N AK WESTERN B N AK INT BSN B A
AK S INT N A AK SO COAST B A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 14 - 20 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A N NRN CALIF A N
SRN CALIF A N 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 N N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A N OKLAHOMA A A
N TEXAS N A S TEXAS B A W TEXAS A A
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS A N LOUISIANA N N WISCONSIN A B
ILLINOIS A B MISSISSIPPI N N MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY N B
TENNESSEE N B ALABAMA N 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 N B NEW JERSEY N B W VIRGINIA N B
MARYLAND N B DELAWARE N B VIRGINIA N B
N CAROLINA N A S CAROLINA N A GEORGIA N A
FL PNHDL B A FL PENIN N A AK N SLOPE B N
AK ALEUTIAN B N AK WESTERN B N AK INT BSN B A
AK S INT B A AK SO COAST B 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.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page