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FXUS06 KWBC 231902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED OCTOBER 23 2024
6-10 DAY OUTLOOK FOR OCT 29 - NOV 02, 2024
A HIGHLY AMPLIFIED 500-HPA HEIGHT PATTERN IS FORECAST ACROSS THE CONTIGUOUS
U.S. (CONUS) AT THE START OF THE 6-10 DAY FORECAST PERIOD, WITH RIDGING
(TROUGHING) OVER THE EAST (WEST). THE OVERALL PROGRESSION OF THE MID-LATITUDE
WAVE TRAIN IS FORECAST TO SLOW DOWN COMPARED TO THE DAYS LEADING UP TO THE
PERIOD, WITH THE RIDGE OVER THE EAST LIKELY REMAINING IN PLACE OR SLIGHTLY
RETROGRADING AS THE TROUGHING IN THE WEST WEAKENS. FOLLOWING BRIEF RIDGING
ACROSS SOUTHERN ALASKA EARLY IN THE PERIOD, A MORE PERSISTENT LONGWAVE TROUGH
IS PREDICTED TO DEVELOP ACROSS ALASKA BY DAY-10. THE MANUAL HEIGHT BLEND FOR
THE PERIOD AS A WHOLE DEPICTS POSITIVE HEIGHT ANOMALIES FROM THE EASTERN GREAT
PLAINS TO THE ATLANTIC COAST, WITH THE HIGHEST ANOMALIES (+150 METERS) OVER THE
NORTHEAST. CONVERSELY, NEGATIVE HEIGHT ANOMALIES ARE INDICATED ACROSS THE
WESTERN HALF OF THE CONUS, EXTENDING THROUGH MUCH OF ALASKA, AND INCREASING IN
MAGNITUDE OVER THE BERING SEA. NEAR- TO SLIGHTLY ABOVE-NORMAL HEIGHTS ARE
PREDICTED ACROSS SOUTHEAST ALASKA AND HAWAII.
EXPANSIVE POSITIVE 500-HPA HEIGHT ANOMALIES PREDICTED OVER THE CENTRAL AND
EASTERN CONUS FAVOR ELEVATED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES FROM
THE GREAT PLAINS TO THE EASTERN SEABOARD, WITH THE HIGHEST CHANCES (GREATER
THAN 90 PERCENT) ACROSS THE GREAT LAKES. THE FORECAST CONSOLIDATION DEPICTS A
LARGE REGION OF THE EAST-CENTRAL CONUS WITH MEAN TEMPERATURE ANOMALIES
EXCEEDING +10 DEG F FOR THE ENTIRE PERIOD. NEAR- TO BELOW-NORMAL TEMPERATURES
ARE FAVORED FROM THE WEST COAST TO THE ROCKIES ASSOCIATED WITH INCREASED
TROUGHING OVER THE REGION. TROUGHING OVER THE BERING SEA FAVORS INCREASED
CHANCES FOR BELOW-NORMAL TEMPERATURES OVER THE FAR WESTERN MAINLAND AND PARTS
OF THE ALEUITANS. ANOMALOUSLY LOW SEA ICE ACROSS THE BEAUFORT SEA FAVORS
SLIGHTLY ABOVE-NORMAL TEMPERATURES ACROSS THE NORTH SLOPE. FORECAST TOOLS ARE
GENERALLY WARMER ACROSS MAINLAND ALASKA COMPARED TO YESTERDAY. THIS MAY BE
ATTRIBUTED TO THE TROUGH MOVING CLOSER TO THE STATE LATER IN THE PERIOD,
ALLOWING FOR AN INCREASE IN SOUTHWESTERLY FLOW OVER EASTERN ALASKA. DUE TO A
POTENTIAL WARMING TREND, NEAR-NORMAL TEMPERATURES ARE FORECAST OVER MUCH OF
MAINLAND ALASKA, WITH PROBABILITIES FOR BELOW-NORMAL TEMPERATURES REMAINING
INCREASED ACROSS SOUTHEAST ALASKA.
TROUGHING OVER THE WESTERN CONUS TILTS THE ODDS TOWARDS ABOVE-NORMAL
PRECIPITATION FOR MUCH OF THE WESTERN AND CENTRAL CONUS, WITH ENHANCED ODDS
(GREATER THAN 50 PERCENT) OVER PORTIONS OF THE NORTHERN AND CENTRAL PLAINS AND
UPPER MIDWEST DUE TO THE POTENTIAL FOR LEE CYCLOGENESIS AND ENHANCED BAROCLINIC
INSTABILITY GIVEN THE STRONG TROUGH-RIDGE DIPOLE PREDICTED OVER THE CONUS
DURING THE PERIOD. WHILE THE ECENS REFORECAST TOOL IS PARTICULARLY ROBUST WITH
HIGH CHANCES FOR ABOVE-NORMAL PRECIPITATION ACROSS THE SOUTH-CENTRAL CONUS, THE
UNCALIBRATED FORECAST TOOLS SUPPORT KEEPING THE HIGHEST PROBABILITIES FURTHER
TO THE NORTH AND THIS IS REFLECTED IN THE FORECAST. MUCH OF THE MID-ATLANTIC
AND NORTHEAST U.S. TILTS TOWARDS BELOW-NORMAL PRECIPITATION WITH POSITIVE
500-HPA HEIGHT ANOMALIES OVER THE REGION. ABOVE-NORMAL PRECIPITATION CHANCES
ARE ELEVATED ACROSS PARTS OF FLORIDA AND THE SOUTHEAST DUE TO A POSSIBLE
INCREASE IN TROPICAL MOISTURE ORIGINATING IN THE CARIBBEAN. THE SYNOPTIC
PATTERN OVER THE ALASKA REGION TENDS TO FAVOR STORMIER CONDITIONS OVER THE GULF
OF ALASKA AND ABOVE-NORMAL PRECIPITATION FOR MUCH OF THE STATE, ESPECIALLY
ALONG THE SOUTHERN COAST. PREVAILING WINDS OVER THE NORTH PACIFIC CROSS A LONG
FETCH OF WARM WATERS, WEAKLY FAVORING ABOVE-NORMAL PRECIPITATION AND STRONGLY
FAVORING ABOVE-NORMAL TEMPERATURES FOR HAWAII.
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, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF
TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8, AND 20% 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
A HIGHLY AMPLIFIED PATTERN AT THE START OF THE FORECAST PERIOD, OFFSET BY SOME
UNCERTAINTY REGARDING THE PRECIPITATION FORECAST ACROSS THE CENTRAL CONUS, AND
CHANGES IN THE TEMPERATURE GUIDANCE ACROSS ALASKA COMPARED TO YESTERDAY.
8-14 DAY OUTLOOK FOR OCT 31 - NOV 06, 2024
THE WEEK-2 FORECAST EVOLUTION BECOMES MORE UNCLEAR ACROSS THE CONUS RELATIVE TO
THE 6-10 DAY PERIOD, WITH A GRADUAL LESSENING OF THE AMPLIFICATION AS THE
PERIOD PROGRESSES. WHILE THERE IS MORE CONFIDENCE EARLY IN THE PERIOD, ENSEMBLE
VARIABILITY INCREASES DURING THE SECOND HALF OF WEEK-2. THIS IS LIKELY RELATED
TO SEVERAL COMPETING MODES OF VARIABILITY IN THE TROPICS AND HIGH LATITUDES
INCLUDING THE ARCTIC OSCILLATION TRENDING FROM A POSITIVE TO NEUTRAL PHASE, THE
MJO REACHING THE WESTERN HEMISPHERE (PHASE 8), AND THE INFLUENCE FROM THE
TRANSITION TO LA NINA. THE WEEK-2 MANUAL HEIGHT BLEND IS LARGELY DRIVEN BY THE
EARLY PART OF THE PERIOD AND DEPICTS POSITIVE HEIGHT ANOMALIES ACROSS THE
CENTRAL AND EASTERN CONUS, AND CLOSER TO NORMAL HEIGHTS OVER MOST OF THE
INTERIOR WEST. ENHANCED RIDGING PREDICTED OVER THE NORTHEAST PACIFIC FAVORS
WEAKLY POSITIVE HEIGHT ANOMALIES EXTENDING INTO THE NORTHWESTERN CONUS, WITH
THE ECENS AND CMCE MORE ROBUST WITH THIS FEATURE COMPARED TO THE GEFS.
TROUGHING AND NEGATIVE HEIGHT ANOMALIES ARE FAVORED TO PERSIST ACROSS MUCH OF
ALASKA, WITH NEAR- TO SLIGHTLY ABOVE-NORMAL HEIGHTS FORECAST FOR EXTREME
SOUTHEASTERN ALASKA AND HAWAII.
THE RIDGE OVER THE EASTERN CONUS CONTINUES TO FAVOR ABOVE-NORMAL TEMPERATURES
FOR MOST OF THE CONUS EAST OF THE ROCKIES. CHANCES OF ABOVE-NORMAL TEMPERATURES
CONTINUE TO BE HIGH, WITH A BROAD AREA OF AT LEAST 70 PERCENT CHANCES
HIGHLIGHTED EAST OF THE MISSISSIPPI RIVER. CHANCES FOR BELOW-NORMAL
TEMPERATURES REMAIN ELEVATED OVER THE WEST DUE TO TROUGHING FORECAST EARLY IN
THE PERIOD. TROUGHING MOVING OVER ALASKA FAVORS INCREASED SOUTHWESTERLY FLOW
OVER THE EASTERN PORTION OF THE MAINLAND WITH INCREASED CHANCES FOR NEAR- TO
ABOVE-NORMAL TEMPERATURES. HIGHER CHANCES ARE DEPICTED ALONG THE NORTH SLOPE
DUE TO ANOMALOUSLY LOW SEA ICE OVER THE BEAUFORT SEA. PROBABILITIES FOR
BELOW-NORMAL TEMPERATURES ARE INCREASED ACROSS THE FAR WESTERN MAINLAND, PARTS
OF THE ALEUTIANS, AND SOUTHEAST ALASKA. HAWAII CONTINUES TO TILT STRONGLY
TOWARDS ABOVE-NORMAL TEMPERATURES, CONSISTENT WITH THE ERF CONSOLIDATION AND
HAWAII FORECAST TOOLS.
MUCH OF THE CENTRAL CONUS CONTINUES TO TILT TOWARDS ABOVE-NORMAL PRECIPITATION
FOR WEEK-2. ODDS ARE LOWER WEST OF THE ROCKIES AS THE TROUGH SHIFTS EASTWARD
AND BEGINS TO WEAKEN, SLIGHTLY ELEVATED CHANCES OF BELOW-NORMAL PRECIPITATION
FORECAST ACROSS PARTS OF CALIFORNIA, NEVADA, AND SOUTHERN OREGON. AS MENTIONED
IN THE 6-10 DAY DISCUSSION, A STRONG BAROCLINIC ZONE IS FORECAST TO BE SET UP
ACROSS THE CENTRAL CONUS EARLY IN THE PERIOD FAVORING ELEVATED PROBABILITIES OF
ABOVE-NORMAL PRECIPITATION. THE GEFS AND ECENS BOTH INDICATE AN ENHANCEMENT OF
THE PROBABILITIES ACROSS THE SOUTHERN HIGH PLAINS SUGGESTIVE OF A STALLED
FRONTAL BOUNDARY OVER THE REGION AS THE MID-LEVEL PATTERN PROGRESSION SLOWS
DOWN. THE ABOVE-NORMAL PROBABILITIES ALSO EXTEND TO PARTS OF FLORIDA AND THE
SOUTHEAST DUE TO THE POSSIBLE NORTHWARD PROGRESSION OF TROPICAL MOISTURE. NEAR-
TO BELOW-NORMAL PRECIPITATION REMAINS FAVORED FOR MUCH OF THE MID-ATLANTIC AND
NORTHEAST UNDERNEATH THE CONTINUED INFLUENCE OF POSITIVE 500-HPA HEIGHT
ANOMALIES. TROUGHING OVER ALASKA FAVORS A PERSISTENT STORMY PATTERN ACROSS THE
STATE, WITH THE HIGHEST ODDS FOR ABOVE-NORMAL PRECIPITATION ACROSS THE SOUTHERN
COAST. ABOVE-NORMAL PRECIPITATION REMAINS FAVORED ACROSS HAWAII, WITH THE
EXCEPTION OF KAUAI, WHERE NEAR-NORMAL PRECIPITATION IS FORECAST.
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, WITH
REASONABLE AGREEMENT AMONG MODELS REGARDING THE SYNOPTIC PATTERN AT THE START
OF WEEK-2, OFFSET BY LARGE SPREAD IN MODEL ENSEMBLES EMERGING LATER IN THE
PERIOD.
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
NOVEMBER 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:
19831003 - 19561023 - 19711030 - 19731003 - 19831009
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:
19831003 - 19831008 - 19561024 - 19731002 - 19561010
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 29 - NOV 02, 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B N
SRN CALIF B N IDAHO B A NEVADA B A
W MONTANA B A E MONTANA B A WYOMING B A
UTAH B A ARIZONA B A COLORADO B A
NEW MEXICO A A N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN A A
ILLINOIS A A MISSISSIPPI A A MICHIGAN A A
INDIANA A A OHIO A N KENTUCKY A A
TENNESSEE A N ALABAMA A N NEW YORK A B
VERMONT A N NEW HAMP A B MAINE A N
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 N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A A AK N SLOPE N A
AK ALEUTIAN N A AK WESTERN N A AK INT BSN N A
AK S INT N A AK SO COAST N A AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 31 - NOV 06, 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B N OREGON B N NRN CALIF B B
SRN CALIF B N IDAHO B N NEVADA B N
W MONTANA B N E MONTANA N A WYOMING B A
UTAH B A ARIZONA B N COLORADO N A
NEW MEXICO N A N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN A A
ILLINOIS A A MISSISSIPPI A A MICHIGAN A A
INDIANA A A OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA A N NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS A B
PENN A N NEW JERSEY A N W VIRGINIA A N
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A N S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B A AK WESTERN N A AK INT BSN A A
AK S INT N A AK SO COAST N A AK PNHDL N 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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