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FXUS06 KWBC 212002
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST TUE NOVEMBER 21 2023
6-10 DAY OUTLOOK FOR NOV 27 - DEC 01, 2023
DYNAMICAL MODELS REMAIN IN GOOD AGREEMENT REGARDING THE 500-HPA GEOPOTENTIAL
HEIGHT PATTERN AT THE BEGINNING OF THE 6-10 DAY PERIOD, WITH ANOMALOUS
TROUGHING (RIDGING) ACROSS EASTERN (WESTERN) NORTH AMERICA. THE EVOLUTION OF
THE PATTERN TOWARD THE END OF THE PERIOD IS MORE UNCERTAIN ACROSS THE WEST,
WITH THE GEFS DEPICTING LARGE-SCALE TROUGHING BUILDING ACROSS THE EASTERN
PACIFIC AND WESTERN CONUS, WHILE THE ECMWF AND CANADIAN ENSEMBLES DEPICT
TROUGHING OVER THE SOUTHWESTERN CONUS, AND RIDGING PERSISTING ACROSS WESTERN
CANADA. TODAY’S MANUAL 500-HPA HEIGHT BLEND INDICATES ABOVE-NORMAL HEIGHTS
ACROSS MUCH OF THE WESTERN CONUS EXTENDING THROUGH MOST OF MAINLAND AND
SOUTHEAST ALASKA. BELOW-NORMAL HEIGHTS ARE FAVORED ACROSS THE EASTERN HALF OF
THE CONUS, EXTREME WESTERN MAINLAND ALASKA, THE ALEUTIANS, AND HAWAII.
NOVEMBER IS FORECAST TO END ON THE COLDER SIDE ACROSS MOST OF THE EASTERN CONUS
WITH MOST AREAS HAVING INCREASED PROBABILITIES FOR BELOW-NORMAL TEMPERATURES,
WITH THE EXCEPTION OF THE SOUTHERN FLORIDA PENINSULA WHERE ABOVE-NORMAL
TEMPERATURE PROBABILITIES ARE ELEVATED TO THE SOUTH OF THE FRONTAL BOUNDARY.
THE LARGEST PROBABILITIES FOR BELOW-NORMAL TEMPERATURES (GREATER THAN 60
PERCENT) ARE PREDICTED FROM THE SOUTHERN PLAINS EXTENDING THROUGH THE OHIO AND
TENNESSEE VALLEYS INTO PARTS OF THE MID-ATLANTIC AND NORTHEAST, WHERE AVERAGE
TEMPERATURES 5 TO 10 DEG F BELOW-NORMAL ARE POSSIBLE BASED ON THE UNCALIBRATED
0Z GEFS AND ECMWF ENSEMBLES. WHILE BELOW-NORMAL TEMPERATURES ARE ALSO FORECAST
ACROSS THE WEST, SOME MODERATION IS POSSIBLE TOWARD THE END OF THE PERIOD, WITH
THE ECMWF REFORECAST TOOL BEING QUITE ROBUST WITH ELEVATED PROBABILITIES FOR
ABOVE-NORMAL TEMPERATURES DEPICTED ACROSS THE WEST COAST, AND EXTENDING ACROSS
THE NORTHERN ROCKIES AND PLAINS. HOWEVER, GIVEN THE LOWER PROBABILITIES FOR
ABOVE-NORMAL TEMPERATURES IN THE GEFS REFORECAST TOOL, AND THE STRONGER SIGNAL
FOR BELOW-NORMAL TEMPERATURES IN THE UNCALIBRATED GUIDANCE, INCREASED CHANCES
FOR BELOW-NORMAL TEMPERATURES REMAIN FAVORED ACROSS MUCH OF THE INTERIOR WEST,
WITH A TILT TOWARD ELEVATED ABOVE-NORMAL TEMPERATURE PROBABILITIES ACROSS PARTS
OF CALIFORNIA, THE PACIFIC NORTHWEST, AND THE EXTREME NORTHERN ROCKIES AND HIGH
PLAINS. RIDGING ACROSS ALASKA FAVORS HIGH PROBABILITIES (SOME AREAS GREATER
THAN 70 PERCENT) FOR ABOVE-NORMAL TEMPERATURES ACROSS THE STATE. CONVERSELY,
ELEVATED PROBABILITIES FOR BELOW-NORMAL TEMPERATURES ARE FAVORED ACROSS HAWAII,
COINCIDING WITH THE FORECAST NEGATIVE 500-HPA HEIGHT ANOMALIES.
THE OVERALL HEIGHT PATTERN GENERALLY FAVORS A MORE SUPPRESSED STORM TRACK
ACROSS THE CONUS LEADING TO INCREASED PROBABILITIES OF BELOW-NORMAL
PRECIPITATION OVER MOST AREAS, EXCLUDING THE SOUTH-CENTRAL AND SOUTHEASTERN
STATES WHERE ABOVE-NORMAL PRECIPITATION PROBABILITIES ARE INCREASED ALONG THE
MEAN FRONTAL BOUNDARY AND CONSISTENT WITH THE EL NINO CLIMATOLOGY. THIS PATTERN
IS GENERALLY SUPPORTED BY THE GEFS AND ECMWF REFORECAST TOOLS, WITH THE ECMWF
DEPICTING MORE OF A NORTHWARD EXPANSION OF THE ELEVATED ABOVE-NORMAL
PRECIPITATION PROBABILITIES COMPARED TO THE GEFS, ALONG WITH A STRONGER SIGNAL
ACROSS THE FLORIDA PENINSULA. THERE ARE SOME INDICATIONS OF A LOW PRESSURE
SYSTEM CONSOLIDATING ACROSS THE NORTHEAST EARLY IN WEEK-2, ALTHOUGH THE
SUPPRESSED SOUTHERN STREAM MAKES THIS MORE UNCERTAIN, WITH NEAR-NORMAL
PRECIPITATION FORECAST ACROSS NEW ENGLAND FOR THE PERIOD. MODELS ARE IN GOOD
AGREEMENT REGARDING SURFACE LOW PRESSURE OVER THE BERING SEA AND STRONG
SOUTHERLY FLOW ACROSS ALASKA RESULTING IN ELEVATED PROBABILITIES OF
ABOVE-NORMAL PRECIPITATION ACROSS THE STATE. A SLIGHT TILT TOWARDS ELEVATED
ABOVE-NORMAL PRECIPITATION PROBABILITIES IS INDICATED FOR THE HAWAIIAN ISLANDS,
IN PROXIMITY TO A MID-LEVEL TROUGH.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON
DAY 8, 30% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF
TODAY'S OPERATIONAL 0Z ECMWF 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
VERY GOOD MODEL AGREEMENT ON A PERSISTENT 500-HPA HEIGHT PATTERN ACROSS NORTH
AMERICA, WITH SOME UNCERTAINTY IN THE PATTERN EVOLUTION LATE IN THE PERIOD OVER
WESTERN NORTH AMERICA.
8-14 DAY OUTLOOK FOR NOV 29 - DEC 05, 2023
TROUGHING OVER THE EASTERN CONUS IS FORECAST TO WEAKEN DURING WEEK-2 WITH A
TREND TOWARD HIGHER MID-LEVEL HEIGHTS. THE GEFS CONTINUES TO DEPICT A QUICK
TRANSITION TO TROUGHING ALONG THE WEST COAST AROUND DAY-10, WITH THE ECMWF
ENSEMBLE INDICATING A SLOWER TRANSITION AND MORE RIDGING PERSISTING OVER
WESTERN CANADA. HOWEVER, BY THE END OF THE PERIOD, BOTH MODELS ARE IN BETTER
AGREEMENT WITH BROAD RIDGING ACROSS CENTRAL NORTH AMERICA AND TROUGHING OFF THE
WEST COAST, ALIGNING MORE WITH MJO COMPOSITES. DUE TO THE TRANSITIONAL PATTERN,
CLOSER TO NORMAL 500-HPA HEIGHTS ARE INDICATED ACROSS MOST OF THE CONUS IN
TODAY’S MANUAL BLEND, WITH SLIGHTLY ABOVE-NORMAL HEIGHTS FORECAST ACROSS THE
NORTHWESTERN AND NORTH-CENTRAL CONUS. THE TREND TOWARD MORE TROUGHING ACROSS
THE NORTH PACIFIC FAVORS DECREASING MID-LEVEL HEIGHTS ACROSS ALASKA, WITH NEAR-
TO BELOW-NORMAL HEIGHTS INDICATED ACROSS THE MAINLAND AND ALEUTIANS FOR THE
PERIOD AS A WHOLE. ABOVE-NORMAL HEIGHTS REMAIN FAVORED ACROSS SOUTHEAST ALASKA.
WEAKENING TROUGHING IN THE VICINITY OF HAWAII FAVORS NEAR-NORMAL HEIGHTS ACROSS
THE STATE FOR WEEK-2.
WHILE WEEK-2 IS FORECAST TO START OUT WITH BELOW-NORMAL TEMPERATURES ACROSS
MUCH OF THE CONUS, A WARMING TREND IS LIKELY TO TAKE PLACE, ESPECIALLY ACROSS
THE WESTERN AND CENTRAL STATES. FORECAST TOOLS GENERALLY MAINTAIN ELEVATED
PROBABILITIES OF BELOW-NORMAL TEMPERATURES ACROSS THE EASTERN CONUS, ALIGNING
WITH TODAY’S FORECAST, ALTHOUGH PROBABILITIES ARE REDUCED COMPARED TO THE 6-10
DAY OUTLOOK. SOME GEFS AND ECMWF ENSEMBLE MEMBERS SUGGEST THE DEVELOPMENT OF A
POSITIVE NORTH ATLANTIC OSCILLATION IN EARLY DECEMBER, WHICH COULD FURTHER
ENHANCE THE WARMING TREND AT THE END OF WEEK-2. THE GEFS AND ECMWF REFORECAST
TOOLS BOTH SHOW ELEVATED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ACROSS THE
WESTERN AND NORTH-CENTRAL CONUS DURING WEEK-2. HOWEVER, BELOW-NORMAL
TEMPERATURE PROBABILITIES REMAIN ELEVATED IN THE UNCALIBRATED ECMWF, AND GIVEN
THE UNCERTAINTY IN THE SPEED OF THE PATTERN TRANSITION, NEAR-NORMAL TEMPERATURE
PROBABILITIES ARE FAVORED FOR WEEK-2 AS A WHOLE ACROSS THE INTERIOR WEST, WITH
ABOVE-NORMAL TEMPERATURE PROBABILITIES ELEVATED CLOSER TO THE WEST COAST AND
ACROSS PARTS OF THE NORTHWESTERN AND NORTH-CENTRAL CONUS. WHILE RIDGING IS
FORECAST TO WEAKEN ACROSS ALASKA, ENHANCED SOUTHERLY FLOW AHEAD OF TROUGHING
FAVORS A CONTINUATION OF INCREASED ABOVE-NORMAL TEMPERATURE PROBABILITIES
ACROSS MOST OF THE STATE. WEAKENING TROUGHING NEAR HAWAII FAVORS A TRANSITION
TO ELEVATED NEAR- TO ABOVE-NORMAL TEMPERATURE PROBABILITIES ACROSS THE ISLANDS.
THE WEEK-2 PRECIPITATION PATTERN IS SIMILAR TO THE 6-10 DAY PERIOD WITH
INCREASED PROBABILITIES FOR BELOW-NORMAL PRECIPITATION DEPICTED ACROSS MUCH OF
THE NORTHERN TWO-THIRDS OF THE CONUS. PROBABILITIES FOR ABOVE-NORMAL
PRECIPITATION REMAIN ELEVATED ACROSS THE SOUTH-CENTRAL AND SOUTHEASTERN STATES
GIVEN THE POTENTIAL FOR AT LEAST ONE DISTURBANCE TO DEVELOP ALONG THE MEAN
FRONTAL BOUNDARY. THE TREND TOWARD MORE TROUGHING ACROSS THE EAST PACIFIC
FAVORS AN INCREASE IN ONSHORE FLOW ACROSS THE WEST COAST, WITH THE GEFS BEING
THE QUICKEST AND SHOWING THE STRONGEST SIGNAL FOR ABOVE-NORMAL PRECIPITATION
OVER THE WEST, EXTENDING FROM THE FOUR CORNERS TO THE PACIFIC NORTHWEST.
HOWEVER TODAY’S FORECAST IS MORE TONED DOWN GIVEN THE UNCERTAINTY AND THE
RELATIVELY DRIER ECMWF GUIDANCE, BUT STILL INDICATES SLIGHTLY ENHANCED
PROBABILITIES FOR NEAR- TO ABOVE-NORMAL PRECIPITATION ALONG THE WEST COAST.
INCREASED SOUTHERLY ONSHORE FLOW ACROSS ALASKA SUPPORTS ELEVATED CHANCES OF
ABOVE-NORMAL PRECIPITATION OVER THE STATE. PROBABILITIES FOR ABOVE-NORMAL
PRECIPITATION ARE INCREASED OVER HAWAII AS WELL, CONSISTENT WITH THE
UNCALIBRATED GEFS AND ECMWF ENSEMBLES.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 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 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
GENERALLY GOOD MODEL AGREEMENT REGARDING SURFACE FEATURES, BUT WITH INCREASING
UNCERTAINTY RELATED TO A TRANSITIONAL MID-LEVEL PATTERN.
FORECASTER: THOMAS COLLOW
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:
19871108 - 19811107 - 19591129 - 19881202 - 19891129
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:
19871109 - 19801031 - 19891203 - 19881203 - 19581031
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR NOV 27 - DEC 01, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N B OREGON N B NRN CALIF A N
SRN CALIF N N IDAHO N B NEVADA N B
W MONTANA N B E MONTANA N B WYOMING B B
UTAH B B ARIZONA B N COLORADO B B
NEW MEXICO B N N DAKOTA N B S DAKOTA B B
NEBRASKA B B KANSAS B B OKLAHOMA B B
N TEXAS B N S TEXAS B A W TEXAS B N
MINNESOTA B B IOWA B B MISSOURI B B
ARKANSAS B B LOUISIANA B A WISCONSIN B B
ILLINOIS B B MISSISSIPPI B B MICHIGAN B B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE B B ALABAMA B B NEW YORK B B
VERMONT B B NEW HAMP B N MAINE B N
MASS B N CONN B N RHODE IS B N
PENN B B NEW JERSEY B B W VIRGINIA B B
MARYLAND B B DELAWARE B B VIRGINIA B B
N CAROLINA B A S CAROLINA B A GEORGIA B A
FL PNHDL B A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN A A AK WESTERN A 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 NOV 29 - DEC 05, 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 N
W MONTANA A B E MONTANA A B WYOMING N B
UTAH N B ARIZONA N N COLORADO N B
NEW MEXICO N A N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS N N OKLAHOMA N A
N TEXAS B A S TEXAS B A W TEXAS N A
MINNESOTA A B IOWA A B MISSOURI N B
ARKANSAS B N LOUISIANA B A WISCONSIN N B
ILLINOIS N B MISSISSIPPI B N MICHIGAN N B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE B B ALABAMA B N NEW YORK B B
VERMONT B B NEW HAMP B B MAINE B B
MASS B N CONN B N RHODE IS B N
PENN B B NEW JERSEY B N W VIRGINIA B B
MARYLAND B N DELAWARE B N VIRGINIA B N
N CAROLINA B A S CAROLINA B A GEORGIA B A
FL PNHDL B A FL PENIN B A AK N SLOPE A A
AK ALEUTIAN A A 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.
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