162
FXUS06 KWBC 041912
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 04 2023
6-10 DAY OUTLOOK FOR OCT 10 - 14 2023
MODELS ARE IN VERY GOOD AGREEMENT SHOWING THE 6-10 DAY PERIOD STARTING OUT
FAIRLY AMPLIFIED, WITH MID-LEVEL TROUGHS OVER THE EASTERN NORTH PACIFIC AND THE
EASTERN CONUS WHILE A STRONG ANOMALOUS RIDGE IS CENTERED SOUTH OF GREENLAND.
THERE ARE RELATIVELY MINOR DIFFERENCES IN THE DETAILS, BUT THERE IS ONE CHANGE
FROM YESTERDAY IN ALL OF THE MODEL AND ENSEMBLE MEAN SOLUTIONS - THE MID-LEVEL
TROUGH IN THE NORTH PACIFIC OCEAN EXTENDS EASTWARD THROUGH THE NORTHWESTERN
CONUS, AND A PIECE OF VORTICITY IS EJECTED OUT OF THIS FEATURE WHICH TRACKS
THROUGH THE CENTRAL AND EASTERN CONUS. THIS FEATURE MAY BRING WETTER WEATHER TO
THE MIDDLE AND EASTERN PARTS OF THE COUNTRY THAN WAS FORECAST YESTERDAY, IN
PARTICULAR NEAR THE EAST COAST WHERE SOME GUIDANCE SPINS UP A COASTAL OR
NEAR-COASTAL STORM. IN ADDITION, WHILE THE MID-LEVEL TROUGH OVER THE EASTERN
CONUS WEAKENS, THE ADDITIONAL PIECE OF VORTICITY KEEPS LOWER 500-HPA HEIGHTS
OVER THE EASTERN CONUS LONGER THAN ANTICIPATED YESTERDAY. THE PREPONDERANCE OF
GUIDANCE NOW KEEP MODERATELY BELOW-NORMAL 500-HPA HEIGHTS OVER THE EASTERN
CONUS THROUGH BOTH THE 6-10 AND 8-14 DAY PERIODS. BY THE END OF THE 6-10 DAY
PERIOD, THE PATTERN IS EXPECTED TO RESEMBLE A DE-AMPLIFIED AND SLIGHTLY
RETROGRADED VERSION OF THE INITIAL PATTERN. THE EXCEPTION IS SOUTH OF
GREENLAND. ALL MODEL SOLUTIONS FADE THIS FEATURE WITH TIME, AND TELECONNECTIONS
ALSO INDICATE THAT THE ABOVE-NORMAL 500-HPA HEIGHTS SOUTH OF GREENLAND SHOULD
BE TRANSIENT. WELL ABOVE-NORMAL 500-HPA HEIGHTS SOUTH OF GREENLAND ARE NOT
CONSISTENT WITH A STRONG MID-LEVEL TROUGH OVER THE NORTH-CENTRAL OR
NORTHEASTERN NORTH PACIFIC. RELATIVE TO YESTERDAY, THE DEAMPLIFICATION IS NOT
AS MARKED IN THE PRIMARY FEATURES OUTSIDE THE MID-LEVEL TROUGH IN EASTERN NORTH
AMERICA, AND THERE IS LESS PROGRESSION OF MID-LEVEL FEATURES BEFORE SOME
RETROGRESSION BEGINS TO TAKE PLACE. THIS APPEARS TO BE A RESULT OF THE
MID-LEVEL SHORTWAVE EXPECTED TO TRAVERSE THE CONUS WHICH REINFORCES
BELOW-NORMAL 500-HPA HEIGHTS IN THE EASTERN CONUS ASSOCIATED WITH THE WEAKENING
TROUGH THERE, KEEPING THE FEATURE FROM PROGRESSING AS MUCH AS EXPECTED
YESTERDAY. OVERALL, THERE ARE SOME DISCREPANCIES IN MODEL SOLUTIONS OF THE
HEIGHT FIELDS FROM THE NORTH PACIFIC TO THE NORTH ATLANTIC OCEAN, MOSTLY
REGARDING STRENGTH OF ANOMALIES AND PRECISE LOCATIONS OF INDIVIDUAL FEATURES,
MOST GUIDANCE - ESPECIALLY THE ENSEMBLE MEANS - ARE IN EXCELLENT AGREEMENT
THROUGH TO THE END OF WEEK-2.
THE FAVORED 6-10 DAY PATTERN WOULD LEAD TO BELOW-NORMAL TEMPERATURES ACROSS THE
EAST-CENTRAL CONUS NEAR AND BEHIND THE STRONG MID-LEVEL TROUGH. COLD WEATHER
MAY IMPACT VULNERABLE CROPS DURING THE LAST HALF OF THE PERIOD IN THE OHIO
VALLEY, CENTRAL APPALACHIANS, AND ADJACENT AREAS. MEANWHILE, THE CANADIAN RIDGE
FAVORS ABOVE-NORMAL TEMPERATURES FARTHER WEST FROM THE UPPER MISSISSIPPI VALLEY
AND GREAT PLAINS TO THE WEST COAST, WITH THE BEST ODDS FOR WARMTH EXTENDING
OVER THE NORTHERN HALF OF THE GREAT PLAINS, CLOSEST TO THE MID-LEVEL RIDGE
CENTERED NEAR THE CANADIAN PRAIRIES. MEANWHILE, THE PROXIMITY OF THE MID-LEVEL
TROUGH IN THE NORTH PACIFIC FAVORS COOLER THAN NORMAL WEATHER ACROSS MOST OF
ALASKA, INCLUDING THE ALEUTIANS. ONE EXCEPTION IS IN SOUTHEASTERN ALASKA, WHERE
THE RAW AND BIAS-CORRECTED DYNAMIC MODEL ENSEMBLES FAVOR UNUSUALLY COOL WEATHER
WHILE REFORECAST TOOLS LEAN TOWARD ABOVE-NORMAL TEMPERATURES. GIVEN A GOOD
FETCH OF MILD PACIFIC AIR INTO THE REGION, AND THE CONFLICTING GUIDANCE, THE
OUTLOOK FAVORS NEITHER COLDER NOR WARMER THAN NORMAL WEATHER FOR THE 6-10 DAY
PERIOD. FARTHER SOUTH, COLD SEA SURFACE TEMPERATURES ENHANCE THE CHANCES FOR
SUBNORMAL TEMPERATURES OVER THE BIG ISLAND IN HAWAII, BUT A MID-LEVEL RIDGE
CENTERED TO THE NORTHWEST AND HIGHER SEA SURFACE TEMPERATURES FAVOR ABOVE
NORMAL TEMPERATURES ACROSS THE WESTERN HALF OF THE STATE.
THE NORTH PACIFIC TROUGH ENHANCES THE LIKELIHOOD OF UNUSUALLY WET WEATHER IN
THE NORTHWESTERN CONUS AND EASTERN ALASKA, WITH THE HIGHEST ODDS (OVER 50
PERCENT) COVERING MOST OF OREGON AND WASHINGTON. DOWNSTREAM, THE PIECE OF THE
NORTH PACIFIC TROUGH THAT TRAVERSES THE CONUS CHANGES THE OUTLOOK FROM
YESTERDAY. GUIDANCE IS INCONSISTENT WITH PRECIPITATION IN THE MIDDLE OF THE
CONUS, WITH RAW DYNAMIC MODELS LEANING DRIER AND REFORECAST TOOLS LEANING WET.
THE FEATURE SHOULD TRIGGER AT LEAST SOME PRECIPITATION THERE, BUT IT IS
UNCERTAIN HOW MUCH WILL FALL IN COMPARISON TO NORMAL, SO IN MUCH OF THE MIDDLE
OF THE COUNTRY, NEITHER UNUSUALLY WET NOR UNUSUALLY DRY CONDITIONS ARE
INDICATED. FARTHER EAST, SIMILAR QUESTIONS EXIST REGARDING HOW MUCH MOISTURE
CAN BE ASSIMILATED INTO THE SYSTEM. BUT THERE IS ADDITIONAL UNCERTAINTY
INTRODUCED BY THE DEVELOPMENT OF A COASTAL OR NEAR-COASTAL SURFACE LOW PRESENT
IN SOME OF THE TOOLS. THE EUROPEAN ENSEMBLE MEAN IS FAIRLY ROBUST WITH THIS
SYSTEM AND WITH PRECIPITATION IN THE EASTERN CONUS WHILE THE GEFS IS MORE
SHEARED-OUT, KEEPING THE SYSTEM WEAKER AND FARTHER OUT TO SEA. THE POTENTIAL OF
COASTAL LOW DEVELOPMENT ADDS AN OPPORTUNITY FOR HEAVIER PRECIPITATION IN THE
EASTERN CONUS THAN IS EVIDENT FARTHER WEST, SO ODDS SLIGHTLY FAVORING
ABOVE-NORMAL PRECIPITATION HAVE BEEN INTRODUCED THERE.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 40% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 25% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, 20% OF TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8, AND
15% 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
GENERAL AGREEMENT AMONG THE TOOLS ON THE BROADSCALE PATTERN, WITH THE NOTED
DISCREPANCIES REGARDING THE SENSIBLE WEATHER TRIGGERED BY THE MID-LEVEL SHORT
WAVE TRAVERSING CONUS AFTER BEING EJECTED FROM THE NORTH PACIFIC TROUGH.
8-14 DAY OUTLOOK FOR OCT 12 - 18 2023
DURING WEEK-2, A SLIGHT RETROGRESSION OF FEATURES IS ANTICIPATED, ALONG WITH
DE-AMPLIFICATION OF THE TROUGH NEAR EASTERN NORTH AMERICA. IN ALL MODELS, THE
RETROGRESSION APPEARS LESS PRONOUNCED TODAY THAN YESTERDAY, AND WITH MOST
MID-LEVEL FEATURES REAMPLIFYING SLIGHTLY DURING WEEK-2, THE PATTERN BY THE END
OF THE PERIOD RESEMBLES A SLIGHTLY LESS AMPLIFIED VERSION OF THE PATTERN
EXPECTED ON DAY 6. THE GREENLAND RIDGE AND EASTERN CONUS TROUGH ARE
CONSIDERABLY LESS AMPLIFIED, WITH A COASTAL OR NEAR-COASTAL LOW PRESSURE SYSTEM
POSSIBLE EARLY IN THE PERIOD BEFORE EXITING THE REGION. FARTHER WEST, A
MODERATE MID-LEVEL RIDGE AXIS IS EXPECTED TO STRETCH FROM THE SOUTHWESTERN
CONUS NORTHEASTWARD INTO THE POSITIVE HEIGHT ANOMALY CENTER IN NORTH-CENTRAL
CANADA WHILE A SIGNIFICANT TROUGH IS CENTERED IN THE NORTH PACIFIC, WITH
BELOW-NORMAL 500-HPA HEIGHTS ACROSS ALASKA, AND NEGATIVE HEIGHT ANOMALIES
EXTENDING EASTWARD TO NEAR THE NORTHWESTERN CONUS OR JUST INLAND.
WITH BELOW-NORMAL 500-HPA HEIGHTS HANGING AROUND EASTERN CONUS LONGER THAN
EXPECTED YESTERDAY, THE RELATIVELY COLD AIR IN THE EASTERN CONUS MAY NOT BE
DISLODGED AS QUICKLY DURING WEEK-2, AND THE POTENTIAL FOR COASTAL LOW PRESSURE
DEVELOPMENT FURTHER COMPLICATES THE ISSUE. THIS UNCERTAINTY RESULTS IN A
FORECAST THAT FAVORS NEITHER WARMER NOR COOLER THAN NORMAL WEATHER DURING
WEEK-2 IN MUCH OF THE EASTERN CONUS. ABOVE-NORMAL PRECIPITATION IS FAVORED FROM
PORTIONS OF THE SOUTHEAST UP AND ALONG THE EASTERN SEABOARD DURING THE WEEK-2
PERIOD, PRIMARILY DUE TO THE POTENTIAL FOR COASTAL LOW DEVELOPMENT AROUND THE
MIDDLE OF WEEK-2. FARTHER WEST, WITH MOST AREAS UNDER THE INFLUENCE OF THE
RIDGE AXIS EXTENDING FROM THE SOUTHWEST INTO CANADA, ABOVE-NORMAL TEMPERATURES
APPEAR MOST LIKELY. THE PACIFIC NORTHWEST IS AN EXCEPTION, WITH HEAVIER THAN
NORMAL PRECIPITATION KEEPING TEMPERATURES CLOSER TO NORMAL. GIVEN THE POSITION
OF THE NORTH PACIFIC TROUGH, THE HEAVIER PRECIPITATION MAY OCCUR FARTHER NORTH
IN SOUTHEASTERN ALASKA, BUT THE TOOLS ARE NOT IN GOOD AGREEMENT ON THIS
SCENARIO. STILL THE TROUGH BRINGS SLIGHTLY ENHANCED CHANCES FOR SURPLUS
PRECIPITATION INTO SOUTHEASTERN ALASKA. AS IS THE CASE DURING THE 6-10 DAY
PERIOD, ODDS FAVOR SUBNORMAL TEMPERATURE IN MUCH OF MAINLAND ALASKA AND THE
ALEUTIANS, BUT CONFLICTING SIGNALS BETWEEN THE RAW DYNAMIC MODEL OUTPUT AND THE
REFORECAST TOOLS, NEITHER TEMPERATURE EXTREME IS FAVORED IN SOUTHEASTERN
ALASKA. MEANWHILE, THE PERSISTENCE OF ABOVE-NORMAL 500-HPA HEIGHTS AROUND
HAWAI’I CONTINUES TO FAVOR LESS PRECIPITATION THAN NORMAL ACROSS MOST OF THE
STATE. TEMPERATURES REMAIN FAVORED TO BE BELOW NORMAL ACROSS THE BIG ISLAND
WITH WARMER THAN NORMAL TEMPERATURES ACROSS THE WESTERN PARTS OF THE STATE.
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: ABOVE NORMAL, 4 OUT OF 5, FOR
EXCELLENT AGREEMENT IN THE EVOLUTION OF THE MID-LEVEL HEIGHT PATTERN, TEMPERED
BY DIFFERENCES IN THE TIMING AND MAGNITUDE OF EVOLVING FEATURES, PARTICULARLY
WITH THE SHORT-WAVE TRAVERSING THE CONUS EARLY IN THE PERIOD.
FORECASTER: RICH TINKER
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
OCTOBER 19.
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:
20081010 - 19941015 - 19680921 - 19841014 - 19831001
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:
20081010 - 19941017 - 19680920 - 19841013 - 19830930
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 10 - 14 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON A A NRN CALIF A A
SRN CALIF A N IDAHO A A NEVADA A N
W MONTANA A A E MONTANA A A WYOMING A N
UTAH A N ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A N S DAKOTA A N
NEBRASKA A N KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A N W TEXAS A B
MINNESOTA A N IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA A A WISCONSIN A N
ILLINOIS A N MISSISSIPPI A N MICHIGAN N N
INDIANA N N OHIO B N KENTUCKY N N
TENNESSEE N N ALABAMA A A NEW YORK B N
VERMONT N A NEW HAMP N A MAINE A A
MASS B A CONN B A RHODE IS B A
PENN B N NEW JERSEY B A W VIRGINIA B N
MARYLAND B A DELAWARE B A VIRGINIA B N
N CAROLINA N A S CAROLINA N A GEORGIA N A
FL PNHDL N A FL PENIN N A AK N SLOPE B A
AK ALEUTIAN B B AK WESTERN B B AK INT BSN B A
AK S INT B N AK SO COAST B N AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 12 - 18 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A N
SRN CALIF A N IDAHO A N NEVADA A N
W MONTANA A N E MONTANA A N WYOMING A N
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A N S DAKOTA A N
NEBRASKA A N KANSAS A N OKLAHOMA A B
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA A N IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA A N WISCONSIN A N
ILLINOIS N N MISSISSIPPI A N MICHIGAN A N
INDIANA N N OHIO N N KENTUCKY N N
TENNESSEE N N ALABAMA N A NEW YORK N A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN N A RHODE IS N A
PENN N A NEW JERSEY N A W VIRGINIA N N
MARYLAND N A DELAWARE N A VIRGINIA N A
N CAROLINA N A S CAROLINA N A GEORGIA N A
FL PNHDL N A FL PENIN N A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B B AK INT BSN B N
AK S INT N N AK SO COAST N N 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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