498
FXUS06 KWBC 031926
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE OCTOBER 03 2023
6-10 DAY OUTLOOK FOR OCT 09 - 13 2023
MODELS ARE IN GENERAL 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.
MODELS ARE MORE AMPLIFIED TODAY THAN YESTERDAY, WITH THE ANOMALIES HAVING
GREATER MAGNITUDES THAN YESTERDAY. THE CANADIAN ENSEMBLE MEAN IS STRONGER WITH
THE 500-HPA HEIGHT ANOMALY SOUTH OF GREENLAND, BUT LESS AMPLIFIED THAN THE
OTHERS OVER MOST OF NORTH AMERICA AND THE NORTH PACIFIC OCEAN. AND THE GEFS IS
A BIT STRONGER AND FARTHER SOUTHEAST WITH THE NORTH PACIFIC TROUGH THAN THE
OTHER ENSEMBLE MEANS. MEANWHILE, A MID-LEVEL RIDGE AXIS IS EXPECTED TO BE
STRETCHING FROM A POSITIVE 500-HPA HEIGHT ANOMALY IN CENTRAL CANADA SOUTHWARD
ACROSS THE GREAT PLAINS AND INTO THE SOUTHERN ROCKIES. HEIGHT ANOMALIES ARE
HIGHER IN THE GEFS AND EUROPEAN ENSEMBLE MEANS THAN IN THE CANADIAN ENSEMBLE
MEAN, CONSISTENT WITH ITS OTHER FEATURES BEING LESS AMPLIFIED. BUT DESPITE
THESE INCONSISTENCIES IN THE DETAILS, THE BROAD SCALE PATTERN IS CONSISTENT
AMONG THE MODELS, AND THE DIFFERENCES IN DETAILS DO NOT APPEAR TO HAVE A
SIGNIFICANT EFFECT ON SENSIBLE WEATHER ACROSS THE COUNTRY.
THIS IS LIKELY A TRANSIENT PATTERN, WITH SOME PROGRESSION AND DE-AMPLIFICATION
TAKING PLACE AS THE 6-10 PERIOD PROGRESSES. TELECONNECTIONS INDICATE THAT THE
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.
THIS IS BORNE OUT IN ALL THE ENSEMBLE MEANS, THOUGH AGAIN THERE ARE SOME
DISCREPANCIES REGARDING THE PLACEMENT AND STRENGTH OF SPECIFIC FEATURES,
ESPECIALLY AT THE END OF THE PERIOD. RELATIVE TO YESTERDAY, THE DEAMPLIFICATION
AND PROGRESSION OF MID-LEVEL FEATURES ARE NOT AS MARKED IN THE GUIDANCE, AND
SOME RETROGRESSION MAY BEGIN TOWARD THE END OF THE PERIOD. BY DAY 9, MOST
GUIDANCE SHOWS THE NORTH PACIFIC AND WESTERN NORTH ATLANTIC MID-LEVEL TROUGHS
TO WEAKEN SOME AND BECOME MUCH MORE BROAD. ONE TROUGH IS EXPECTED TO EXTEND
FROM SOUTH OF THE ALEUTIANS EASTWARD INTO OR NEAR WESTERN NORTH AMERICA. THE
EUROPEAN ENSEMBLE SHOWS TWO SEPARATE TROUGHS FORMING - ONE CLOSE TO THE
ALEUTIANS, AND ONE CLOSER TO CANADA. THE BROADER SOLUTION IS PREFERRED AT THIS
TIME, IN LINE WITH THE PREPONDERANCE OF GUIDANCE. MEANWHILE, NEAR THE EASTERN
CONUS, THE DEEP MID-LEVEL TROUGH WEAKENS AND EXPANDS, WITH NEGATIVE MID-LEVEL
HEIGHT ANOMALIES STRETCHING FROM THE EASTERN CONUS INTO THE WESTERN NORTH
ATLANTIC, TO WELL SOUTHEAST OF ATLANTIC CANADA. THE EUROPEAN ENSEMBLE MEAN IS A
LITTLE LESS BROAD, CREATING MORE MERIDIONAL FLOW THAN MOST OTHER GUIDANCE, AS
IS THE CASE IN THE NORTH PACIFIC. THE EUROPEAN ENSEMBLE LOOKS TO BE AN OUTLIER,
SO IS NOT THE FAVORED SOLUTION AT THIS TIME.
THE FAVORED 6-10 DAY PATTERN WOULD LEAD TO BELOW-NORMAL TEMPERATURES ACROSS THE
EASTERN CONUS NEAR AND BEHIND THE STRONG MID-LEVEL TROUGH. COLD WEATHER MAY
IMPACT VULNERABLE CROPS DURING THE LAST HALF OF THE PERIOD IN THE MIDDLE 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 ALASKA,
INCLUDING THE ALEUTIANS. FARTHER SOUTH, COLD SEA SURFACE TEMPERATURES ENHANCE
THE CHANCES FOR SUBNORMAL TEMPERATURES OVER THE BIG ISLAND AND PART OF EASTERN
MAUI IN HAWAII, BUT A MID-LEVEL RIDGE AND MORE TYPICAL 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 WESTERN CONUS, WITH THE HIGHEST ODDS (OVER 60 PERCENT) EXTENDING FROM
NORTHERN CALIFORNIA INTO THE PACIFIC NORTHWEST. THE TROUGH SHOULD ALSO BRING
MORE PRECIPITATION THAN NORMAL TO SOUTHEAST ALASKA AND THE EASTERN PARTS OF
MAINLAND ALASKA. FARTHER EAST, THE DOWNSTREAM ANTI-CYCLONIC MID-LEVEL FLOW
FAVORS BELOW NORMAL PRECIPITATION OVER MOST OF THE CENTRAL AND EASTERN CONUS.
ONE EXCEPTION IS NEW ENGLAND, WHERE THE PROXIMITY OF THE MID-LEVEL TROUGH MAY
HELP BRING ATLANTIC MOISTURE AND PERHAPS A SURFACE LOW PRESSURE SYSTEM INTO THE
REGION. ANOTHER IS THE ENHANCED CHANCES FOR INCREASED RAINFALL NEAR THE
IMMEDIATE GULF COAST AND IN PARTS OF FLORIDA AND SOUTHERN TEXAS, WHERE GULF OF
MEXICO MOISTURE INTRUSION IS POSSIBLE BEGINNING LATE IN THE PERIOD. FARTHER
SOUTH AND WEST, THE MID-LEVEL RIDGE COVERING HAWAII SHOULD FAVOR BELOW NORMAL
PRECIPITATION ACROSS MOST OF THE ISLAND CHAIN.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 40% OF TODAY'S GFS
SUPERENSEMBLE MEAN CENTERED ON DAY 8, 25% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, 15% 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
GENERAL AGREEMENT AMONG THE TOOLS ON THE BROADSCALE PATTERN, WITH THE NOTED
DISCREPANCIES NOT HAVING A DRAMATIC IMPACT ON SENSIBLE WEATHER IN THE CONUS AND
ALASKA.
8-14 DAY OUTLOOK FOR OCT 11 - 17 2023
DURING WEEK-2, RETROGRESSION OF THE DE-AMPLIFIED PATTERN IS EXPECTED, ALONG
WITH SOME RE-AMPLIFICATION OF CERTAIN FEATURES. BY THE END OF THE PERIOD, A
POSITIVE 500-HPA ANOMALY CENTER IS FORECAST NORTH OF THE CANADIAN PRAIRIES
WHILE THE STRONG MID-LEVEL TROUGH NEAR THE WESTERN CONUS IS RE-POSITIONED
WESTWARD, WITH THE AXIS EXTENDING SOUTHWARD INTO THE NORTH PACIFIC WELL WEST OF
THE PACIFIC NORTHWEST. THERE IS A BIT MORE UNCERTAINTY IN THE EAST, BUT 500-HPA
HEIGHTS SHOULD GENERALLY BE NEAR TO SLIGHTLY BELOW NORMAL, WITH A WEAK TROUGH
AXIS FROM NEAR THE NEW ENGLAND COAST SOUTHEASTWARD INTO THE NORTH ATLANTIC, AND
SUBNORMAL 500-HPA HEIGHTS EXTENDING WESTWARD TO THE MISSISSIPPI VALLEY. ALL OF
THE PRIMARY MID-LEVEL FEATURES ARE SHOWN FARTHER WEST AND SLIGHTLY MORE
AMPLIFIED THAN YESTERDAY IN MOST OF THE GUIDANCE.
THE RE-BUILDING HEIGHTS IN CANADA AND THE WEAKENING OF THE MID-LEVEL TROUGH IN
THE EAST SHOULD DISPLACE THE COLD AIR THAT SETTLED INTO THE EASTERN CONUS
DURING THE 6-10 DAY PERIOD, WITH TEMPERATURES CLIMBING ABOVE NORMAL THERE BY
THE END OF WEEK-2. THE SPEED OF THIS TRANSITION IS UNCERTAIN, AS ARE THE
TEMPERATURE ANOMALIES EARLY IN THE PERIOD - GOOD RADIATIONAL COOLING UNDERNEATH
SURFACE HIGH PRESSURE COULD ALLOW NIGHTTIME TEMPERATURES TO DROP LOWER THAN
INDICATED BY GUIDANCE EARLY WEEK-2. THIS UNCERTAINTY LED TO A FORECAST FAVORING
NEITHER COLDER THAN NORMAL NOR WARMER THAN NORMAL TEMPERATURES IN MUCH OF THE
EASTERN SEABOARD, AND ONLY A SLIGHT TILT OF THE ODDS TOWARD WARMTH OVER THE
OHIO VALLEY AND EASTERN GREAT LAKES REGION. ODDS FAVOR ABOVE-NORMAL
TEMPERATURES OVER THE REST OF THE CONUS OUTSIDE THE PACIFIC NORTHWEST, WHERE
HEAVIER THAN NORMAL PRECIPITATION SHOULD KEEP TEMPERATURES CLOSER TO NORMAL.
BUT WITH THE NORTH PACIFIC TROUGH CENTERED FARTHER WEST THAN EXPECTED
YESTERDAY, THE HEAVIER PRECIPITATION MAY OCCUR FARTHER NORTH IN SOUTHEASTERN
ALASKA, BUT THE TOOLS ARE NOT IN GOOD AGREEMENT ON THIS SCENARIO. THE WESTWARD
SHIFT IN OTHER FEATURES ALSO BRINGS CHANGES FARTHER EAST. INCREASING GULF
MOISTURE INTRUSION ENHANCES THE CHANCES FOR ABOVE-NORMAL RAINFALL IN THE GULF
COAST STATES, EXTENDING FARTHER NORTH THAN DURING THE 6-10 DAY PERIOD. MOISTURE
MAY REACH FARTHER NORTH INTO THE PLAINS, LOWERING THE ODDS FOR BELOW-NORMAL
PRECIPITATION THERE. UPPER-LEVEL FEATURES AGAIN INCREASE THE ODDS FOR
DRIER-THAN-NORMAL WEATHER IN THE SOUTHWESTERN AND NORTHEASTERN CONUS, FAR
REMOVED FROM THE GULF OF MEXICO. MEANWHILE, THE PERSISTENCE OF ABOVE-NORMAL
500-HPA HEIGHTS AROUND HAWAI’I CONTINUES TO FAVOR LESS PRECIPITATION THAN
NORMAL ACROSS MOST OF THE STATE.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 35% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 15% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON
DAY 11, 25% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 25% OF
TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: NEAR NORMAL, 3 OUT OF 5, FOR
GENERAL AGREEMENT IN THE EVOLUTION OF THE MID-LEVEL HEIGHT PATTERN, TEMPERED BY
DIFFERENCES IN THE TIMING AND MAGNITUDE OF EVOLVING FEATURES.
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:
19941015 - 19830930 - 20081010 - 19841013 - 19680921
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:
19941015 - 19520912 - 20081010 - 19830930 - 19841013
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 09 - 13 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON N A NRN CALIF N A
SRN CALIF A N IDAHO A A NEVADA A A
W MONTANA A A E MONTANA A A WYOMING A A
UTAH A A ARIZONA A N COLORADO A N
NEW MEXICO A N N DAKOTA A N S DAKOTA A N
NEBRASKA A N KANSAS A B OKLAHOMA A B
N TEXAS A N S TEXAS N A W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS N B LOUISIANA N N WISCONSIN A B
ILLINOIS A 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 N
VERMONT B N NEW HAMP B N MAINE N N
MASS B N CONN B B 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 B S CAROLINA B B GEORGIA B B
FL PNHDL B A FL PENIN B 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 B AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 11 - 17 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON N A NRN CALIF A N
SRN CALIF A N IDAHO A A NEVADA A N
W MONTANA A A E MONTANA A A WYOMING A A
UTAH A N ARIZONA A B COLORADO A N
NEW MEXICO A B N DAKOTA A A S DAKOTA A N
NEBRASKA A N KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS A A W TEXAS A N
MINNESOTA A N IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA A A WISCONSIN A N
ILLINOIS A N MISSISSIPPI A A MICHIGAN A B
INDIANA A N OHIO A B KENTUCKY A N
TENNESSEE A N ALABAMA A A NEW YORK A B
VERMONT A B NEW HAMP A B MAINE A B
MASS N B CONN N B RHODE IS N B
PENN N B NEW JERSEY N B W VIRGINIA N N
MARYLAND N N DELAWARE N N VIRGINIA N N
N CAROLINA N A S CAROLINA N A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE B N
AK ALEUTIAN B N AK WESTERN B N AK INT BSN B N
AK S INT B N AK SO COAST B 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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