364
FXUS06 KWBC 072002
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 07 2023
6-10 DAY OUTLOOK FOR DEC 13 - 17 2023
THE GEFS, ECMWF, AND CANADIAN ENSEMBLE MEANS ARE IN GOOD AGREEMENT DEPICTING A
BROAD 500-HPA RIDGE EXPANDING EASTWARD OVER THE NORTHERN TWO-THIRDS OF THE
CONTIGUOUS U.S. (CONUS). THIS BROAD RIDGE WITH POSITIVE 500-HPA HEIGHT
ANOMALIES ALONG WITH STRONG WEST-TO-EAST SURFACE FLOW ACROSS SOUTHERN CANADA
FAVORS ABOVE-NORMAL TEMPERATURES FOR THE WEST, MUCH OF THE GREAT PLAINS, MIDDLE
TO UPPER MISSISSIPPI VALLEY, AND GREAT LAKES. DOWNSLOPING SURFACE FLOW AND LACK
OF SNOW COVER ENHANCES THE ABOVE-NORMAL TEMPERATURE PROBABILITIES ACROSS THE
NORTHERN GREAT PLAINS. ON DAYS 6 AND 7, TEMPERATURES ARE FORECAST TO AVERAGE
NEAR OR SLIGHTLY BELOW NORMAL ACROSS THE EASTERN AND SOUTH-CENTRAL CONUS. SINCE
A GRADUAL WARMING TREND IS ANTICIPATED BY DAY 10, NEAR NORMAL TEMPERATURES ARE
FAVORED FOR MOST OF THOSE AREAS DURING THIS 5-DAY PERIOD. A SLIGHT TILT TOWARDS
BELOW-NORMAL TEMPERATURES IS FORECAST ACROSS THE EASTERN CAROLINAS BASED ON THE
UNCALIBRATED TEMPERATURE TOOLS.
EXPANSIVE SURFACE HIGH PRESSURE FAVORS BELOW-NORMAL PRECIPITATION THROUGHOUT
MUCH OF THE CONUS. A SOUTHERN STREAM SHORTWAVE LEADS TO INCREASED ABOVE-NORMAL
PRECIPITATION PROBABILITIES ACROSS NEW MEXICO, SOUTHERN GREAT PLAINS, RIO
GRANDE VALLEY, AND THE FLORIDA PENINSULA. ALTHOUGH BELOW-NORMAL PRECIPITATION
IS FAVORED ACROSS THE MID-ATLANTIC, FORECAST CONFIDENCE REMAINS LOW AS SEVERAL
0Z ECMWF ENSEMBLE MEMBERS DEPICT LOW PRESSURE DEVELOPMENT NEAR THE DELMARVA BY
DAY 10. A DRY START IS LIKELY ALONG THE WEST COAST DURING THE 6-10 DAY PERIOD,
BUT PRECIPITATION IS EXPECTED TO INCREASE ACROSS NORTHERN CALIFORNIA AND THE
PACIFIC NORTHWEST BY DAY 9 AS A 500-HPA TROUGH APPROACHES. THEREFORE, NEAR
NORMAL PRECIPITATION IS MOST LIKELY FOR THOSE AREAS.
MODEL SOLUTIONS ARE IN EXCELLENT AGREEMENT ON AN AMPLIFIED 500-HPA RIDGE WEST
OF THE BERING STRAIT WITH A DOWNSTREAM TROUGH OVER ALASKA. THIS LONGWAVE
PATTERN STRONGLY SUPPORTS BELOW-NORMAL TEMPERATURES ACROSS SOUTHWESTERN ALASKA.
INCREASED BELOW-NORMAL TEMPERATURE PROBABILITIES ALSO INCLUDE WESTERN AND
NORTHERN MAINLAND ALASKA, WHILE ONSHORE FLOW FAVORS ABOVE-NORMAL TEMPERATURES
AND PRECIPITATION ACROSS SOUTHEASTERN ALASKA.
BASED ON THE CONSOLIDATION TOOL (SKILL-WEIGHTED GEFS AND ECMWF REFORECASTS),
INCREASED ABOVE-NORMAL TEMPERATURE PROBABILITIES ARE FORECAST FOR HAWAII. NEAR
NORMAL PRECIPITATION IS FAVORED ACROSS MOST OF THE HAWAIIAN ISLANDS EXCEPT FOR
THE BIG ISLAND WHERE BELOW-NORMAL PRECIPITATION PROBABILITIES ARE SLIGHTLY
ELEVATED.
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 15 - 21 2023
THE GEFS, ECMWF, AND CANADIAN ENSEMBLE MEANS MAINTAIN POSITIVE 500-HPA HEIGHT
ANOMALIES ACROSS THE NORTHERN TWO-THIRDS OF THE CONUS. THIS PERSISTENT PATTERN
AND ABSENCE OF ANY NORTHERLY FLOW LEADS TO CONTINUED HIGH FORECAST CONFIDENCE
FOR MILD DECEMBER TEMPERATURES. THE WEEK-2 OUTLOOK DEPICTS AN INCREASED
COVERAGE OF FAVORED ABOVE-NORMAL TEMPERATURES FROM THE 6-10 DAY PERIOD. THE
LARGEST PROBABILITIES (MORE THAN 70 PERCENT) OF ABOVE NORMAL TEMPERATURES ARE
FORECAST ACROSS THE NORTHERN TO CENTRAL GREAT PLAINS AND UPPER MISSISSIPPI
VALLEY. NEAR NORMAL TEMPERATURES ARE LIMITED TO SOUTHERN TEXAS AND PARTS OF THE
SOUTHEAST.
FORECAST CONFIDENCE IS MUCH LOWER IN THE WEEK-2 PRECIPITATION OUTLOOK DUE TO
CONFLICTING SIGNALS AMONG THE TOOLS ACROSS THE WEST AND UNCERTAINTY ON LOW
PRESSURE DEVELOPMENT NEAR THE EAST COAST. SEVERAL ENSEMBLE MEMBERS FROM THE 12Z
GEFS AND 0Z ECMWF MODELS DEPICT LOW PRESSURE DEVELOPMENT NEAR OR OVER THE
MID-ATLANTIC LATER IN WEEK-2. EVEN IF SURFACE LOW DEVELOPMENT WERE TO OCCUR,
THE PREDICTED POSITIVE NAO WOULD FAVOR A FASTER MOVING LOW PRESSURE SYSTEM.
NEAR NORMAL PRECIPITATION IS FAVORED FOR MUCH OF THE MID-ATLANTIC WITH A SLIGHT
WET TILT FORECAST FOR SOUTHEASTERN VIRGINIA. A COUPLE OF SHORTWAVE TROUGHS
SLIGHTLY FAVOR ABOVE-NORMAL PRECIPITATION FOR THE CENTRAL TO SOUTHERN GREAT
PLAINS ALONG WITH PARTS OF THE SOUTHEAST. TO THE NORTH OF THE PREDICTED STORM
TRACK, BELOW-NORMAL PRECIPITATION IS MORE LIKELY ACROSS THE NORTHEAST, UPPER
OHIO VALLEY, GREAT LAKES, AND NORTHERN GREAT PLAINS. A MID-LEVEL TROUGH IS
FORECAST TO WEAKEN AS IT NEARS THE WEST COAST EARLY IN WEEK-2 AND THEN 500-HPA
HEIGHTS ARE PREDICTED TO INCREASE LATER IN THE PERIOD. GIVEN THE VARIABLE
LONGWAVE PATTERN AND DISCREPANCIES AMONG THE TOOLS, THE WEEK-2 PRECIPITATION
OUTLOOK IS BASED MOSTLY ON THE CONSOLIDATION TOOL.
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. BELOW-NORMAL PRECIPITATION IS
SLIGHTLY FAVORED ACROSS THE BIG ISLAND, WHILE NEAR NORMAL PRECIPITATION IS MOST
LIKELY FOR THE REMAINDER OF THE HAWAIIAN ISLANDS.
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: AVERAGE, 3 OUT OF 5, DUE TO GOOD
AGREEMENT AMONG THE TEMPERATURE TOOLS OFFSET BY MORE UNCERTAINTY IN THE
PRECIPITATION OUTLOOK DUE TO WEAK OR CONFLICTING SIGNALS AMONG THE 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:
19871204 - 20011220 - 19811204 - 19981126 - 19931210
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:
20031203 - 19871203 - 19651203 - 20031218 - 19811206
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 13 - 17 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A N NRN CALIF A N
SRN CALIF A B 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 A N DAKOTA A B S DAKOTA A B
NEBRASKA A N KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS N A W TEXAS N 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 A B
TENNESSEE N B ALABAMA N B NEW YORK N B
VERMONT N B NEW HAMP N B MAINE N 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 N N FL PENIN N A AK N SLOPE B N
AK ALEUTIAN B N AK WESTERN B B 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 15 - 21 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A N NRN CALIF A N
SRN CALIF A B IDAHO A N NEVADA A B
W MONTANA A N 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 N 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 N
ARKANSAS A N LOUISIANA A A WISCONSIN A B
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 N W VIRGINIA A B
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A A S CAROLINA A A GEORGIA N N
FL PNHDL N A FL PENIN N A AK N SLOPE B N
AK ALEUTIAN B N AK WESTERN B B AK INT BSN B N
AK S INT N A AK SO COAST N 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