413
FXUS06 KWBC 112002
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST MON DECEMBER 11 2023
6-10 DAY OUTLOOK FOR DEC 17 - 21 2023
THE GEFS, ECMWF, AND CANADIAN ENSEMBLE MEANS DEPICT AN AMPLIFIED 500-HPA TROUGH
OVER THE NORTHEASTERN PACIFIC WITH ENHANCED PACIFIC FLOW DOWNSTREAM OVER NORTH
AMERICA. THE PERSISTENT PACIFIC FLOW LEADS TO A CONTINUATION OF MILD
TEMPERATURES FOR MUCH OF THE CONTIGUOUS U.S. (CONUS) INTO THE LATTER HALF OF
DECEMBER. THE LARGEST PROBABILITIES (MORE THAN 80 PERCENT) FOR ABOVE-NORMAL
TEMPERATURES ARE FORECAST ACROSS THE NORTHERN TO CENTRAL GREAT PLAINS AND UPPER
MISSISSIPPI VALLEY WHERE DAILY TEMPERATURES ARE LIKELY TO AVERAGE MORE THAN 10
DEGREES F ABOVE NORMAL. THE ONE EXCEPTION TO THE FAVORED ABOVE NORMAL
TEMPERATURES IS THE GULF COAST, FLORIDA, AND SOUTHERN TEXAS WHERE A SOUTHERN
STREAM SHORTWAVE TROUGH IS FORECAST TO PROVIDE A COOLING EFFECT. NEAR NORMAL
TEMPERATURES OR A SLIGHT TILT TOWARDS BELOW ARE FAVORED FOR THOSE AREAS.
THE MOST LIKELY AREAS TO EXPERIENCE ABOVE-NORMAL PRECIPITATION ARE CALIFORNIA
AND FLORIDA FROM DECEMBER 17 TO 21. MODEL SOLUTIONS ARE IN GOOD AGREEMENT THAT
AN AMPLIFIED MID-LEVEL TROUGH SHIFTS EASTWARD TO CALIFORNIA LATER IN THIS
PERIOD AND THE CONSOLIDATION TOOL (SKILL-WEIGHTED GEFS AND ECMWF REFORECASTS)
DEPICTS A 40 TO 70 PERCENT CHANCE OF ABOVE-NORMAL PRECIPITATION FOR MOST OF THE
STATE. THESE INCREASED ABOVE-NORMAL PRECIPITATION PROBABILITIES EXTEND EAST TO
PARTS OF THE GREAT BASIN AND SOUTHWEST AS THE MID-LEVEL TROUGH PROGRESSES
INLAND. A SHORTWAVE TROUGH IN THE SOUTHERN STREAM IS FORECAST TO BE OVER THE
WESTERN GULF OF MEXICO ON DAY 6 (DECEMBER 17). GIVEN THE BROAD RIDGING OVER THE
MIDDLE LATITUDES OF EAST-CENTRAL NORTH AMERICA, THE SHORTWAVE TROUGH AND ITS
ASSOCIATED SURFACE LOW PRESSURE SYSTEM ARE EXPECTED TO SLOWLY TRACK EAST OVER
THE GULF OF MEXICO AND FLORIDA. THE DETERMINISTIC 0Z ECMWF AND 0Z CANADIAN
MODELS SHOW LITTLE OR NO INTERACTION WITH THE NORTHERN STREAM AND KEEP THE LOW
PRESSURE SYSTEM CONFINED TO FLORIDA OR THE COASTAL SOUTHEAST. THE DETERMINISTIC
GFS MODEL CONTINUES TO FAVOR A MORE NORTHWARD TRACK ALONG THE EAST COAST, BUT
ITS RECENT ENSEMBLE MEMBERS ARE BEGINNING TO SHOW LESS INTERACTION WITH THE
NORTHERN STREAM. ABOVE-NORMAL PRECIPITATION IS LIKELY ACROSS FLORIDA WITH
ELEVATED ABOVE-NORMAL PRECIPITATION PROBABILITIES EXTENDING NORTH TO THE
EASTERN CAROLINAS. GIVEN THE PREFERRED ECMWF REFORECAST TOOL, BELOW-NORMAL
PRECIPITATION IS SLIGHTLY FAVORED FOR MUCH OF THE MID-ATLANTIC AND NORTHEAST. A
BROAD RIDGE, CENTERED OVER THE ROCKIES, FAVORS BELOW-NORMAL PRECIPITATION FROM
THE APPALACHIANS WESTWARD TO THE ROCKIES.
MODEL SOLUTIONS DEPICT AN AMPLIFIED 500-HPA TROUGH EXTENDING FROM THE EASTERN
BERING SEA SOUTHEASTWARD TO THE GULF OF ALASKA. CONSISTENT WITH THIS LONGWAVE
PATTERN, NEAR TO ABOVE-NORMAL TEMPERATURES AND ABOVE-NORMAL PRECIPITATION ARE
FAVORED FOR ALASKA WITH ENHANCED ONSHORE FLOW LEADING TO INCREASED
PROBABILITIES ACROSS SOUTHEASTERN ALASKA.
NORTHEASTERLY SURFACE FLOW LEADS TO ELEVATED BELOW-NORMAL TEMPERATURE
PROBABILITIES ACROSS HAWAII. THE CONSOLIDATION TOOL SUPPORTS NEAR-NORMAL
PRECIPITATION FOR MUCH OF THE HAWAIIAN ISLANDS WITH BELOW-NORMAL PRECIPITATION
SLIGHTLY FAVORED FOR THE EASTERN BIG ISLAND.
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 AMONG THE TEMPERATURE AND PRECIPITATION TOOLS ALTHOUGH THERE IS
UNCERTAINTY WITH THE PRECIPITATION OUTLOOK ALONG THE EAST COAST.
8-14 DAY OUTLOOK FOR DEC 19 - 25 2023
THE GEFS, ECMWF, AND CANADIAN ENSEMBLE MEANS FEATURE A HIGH AMPLITUDE 500-HPA
TROUGH EXTENDING FROM THE BERING SEA SOUTHEASTWARD TO THE WEST COAST. ALTHOUGH
THE CANADIAN ENSEMBLE MEAN IS SLIGHTLY WEAKER WITH THE SOUTHERN EXTENSION OF
THE TROUGH, MODEL SOLUTIONS CONTINUE TO DEPICT A PERSISTENCE OF ENHANCED
PACIFIC FLOW OVERSPREADING NORTH AMERICA INTO LATE DECEMBER. THEREFORE,
ABOVE-NORMAL TEMPERATURES ARE LIKELY ACROSS NEARLY ALL OF THE CONUS. ONLY
CENTRAL TO SOUTH FLORIDA IS FORECAST TO HAVE NEAR NORMAL TEMPERATURES DUE TO
THE INFLUENCE OF A LOW PRESSURE SYSTEM EARLY IN WEEK-2. ABOVE-NORMAL
TEMPERATURE PROBABILITIES REMAIN LARGEST ACROSS THE NORTHERN TO CENTRAL GREAT
PLAINS AND UPPER MISSISSIPPI VALLEY BASED ON THE LACK OF ANY ANOMALOUS COLD AT
THE HIGHER LATITUDES OF NORTH AMERICA ALONG WITH EXCELLENT AGREEMENT AND
CONTINUITY AMONG THE TEMPERATURE TOOLS. THIS IS ALSO CONSISTENT WITH
TELECONNECTION OUTPUT FROM A POSITIVE (NEGATIVE) 500-HPA HEIGHT ANOMALY OVER
THE GREAT LAKES (WESTERN ALASKA).
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. 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
GREAT PLAINS AS ENSEMBLE MEANS SHOW AN INCREASING WET SIGNAL LATE IN WEEK-2,
DOWNSTREAM OF THE AMPLIFIED TROUGH NEAR THE WEST COAST. A SLOW-MOVING LOW
PRESSURE SYSTEM, AT THE BEGINNING OF WEEK-2, SUPPORTS ELEVATED ABOVE-NORMAL
PRECIPITATION PROBABILITIES ACROSS THE FLORIDA PENINSULA. A BROAD RIDGE ALOFT
WITH POSITIVE 500-HPA HEIGHT ANOMALIES FAVORS BELOW-NORMAL PRECIPITATION ACROSS
MUCH OF THE EASTERN AND NORTH-CENTRAL CONUS.
THE DEEP 500-HPA TROUGH, EXTENDING FROM THE BERING SEA SOUTHEASTWARD TO THE
GULF OF ALASKA, ALONG WITH ENHANCED ONSHORE FLOW FAVORS ABOVE-NORMAL
TEMPERATURES AND PRECIPITATION ACROSS MUCH OF ALASKA.
THE WEEK-2 OUTLOOK FOR HAWAII IS BASED ON THE CONSOLIDATION TOOL WHICH DEPICTS
INCREASED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES AND BELOW-NORMAL
PRECIPITATION.
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 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:
19991214 - 19621204 - 19641209 - 19921213 - 19911122
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:
19991213 - 19911121 - 19991218 - 19641208 - 19961215
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 17 - 21 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 B NEVADA A A
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 A B
N TEXAS A B S TEXAS N B W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA N 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 B MAINE A B
MASS A B CONN A B RHODE IS A N
PENN A B NEW JERSEY A B W VIRGINIA A B
MARYLAND A B DELAWARE A N VIRGINIA A B
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL N A FL PENIN N A AK N SLOPE N N
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 19 - 25 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 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 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 B MISSOURI A N
ARKANSAS A N 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 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 B S CAROLINA A B GEORGIA A B
FL PNHDL A B FL PENIN N A AK N SLOPE A A
AK ALEUTIAN N N AK WESTERN A A 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.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page