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FXUS06 KWBC 021902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE MAY 02 2023
6-10 DAY OUTLOOK FOR MAY 08 - 12 2023
AN AMPLIFIED 500-HPA LONGWAVE PATTERN IS FORECAST ACROSS THE NORTHERN WESTERN
HEMISPHERE DURING THE 6-10 DAY PERIOD, WITH DEEP TROUGHING OVER THE NORTHERN
ATLANTIC AND CANADIAN MARITIMES, RIDGING ACROSS MUCH OF NORTHERN NORTH AMERICA,
AND TROUGHING ALONG THE WEST COAST AT THE ONSET OF THE PERIOD BEFORE RELOADING
NEAR THE ALEUTIAN ISLANDS. ACROSS THE SOUTHERN CONTIGUOUS UNITED STATES
(CONUS), NEAR-NORMAL MEAN 500-HPA HEIGHTS ARE FAVORED. THE NEAR-NORMAL HEIGHTS
MAY ALLOW A SHORTWAVE TROUGH TO DEVELOP AND PROGRESS ACROSS PARTS OF THE
SOUTHERN CONUS DURING THE PERIOD, BRINGING ELEVATED CHANCES FOR UNSETTLED
WEATHER TO THE SOUTHERN PLAINS AND SOUTHEAST U.S.
WITH MEAN LONGWAVE RIDGING DEVELOPING ACROSS THE NORTHEASTERN TWO-THIRDS OF THE
CONUS, ABOVE-NORMAL TEMPERATURES ARE FAVORED. THE STRONGEST CHANCES FOR
ABOVE-NORMAL TEMPERATURES ARE FOCUSED ACROSS THE GREAT PLAINS AND NORTHEAST
WITH SLIGHTLY LOWER CHANCES ACROSS THE SOUTHEAST AND OHIO VALLEY WHERE
SHORTWAVE TROUGHING MAY BRING ENHANCED CLOUD COVER THAT COULD INHIBIT WARMER
TEMPERATURES LATER IN THE PERIOD. ACROSS THE WESTERN CONUS, NEGATIVE 500-HPA
HEIGHT ANOMALIES ARE FORECAST TO LINGER FOR MUCH OF THE PERIOD, BRINGING
CONTINUED CHANCES FOR BELOW-NORMAL TEMPERATURES DURING THE FORECAST PERIOD. IN
ALASKA, THE REFORECAST GUIDANCE INDICATES INCREASED CHANCES FOR NEAR-NORMAL
TEMPERATURES FOR SOUTHERN PORTIONS OF THE STATE COMPARED TO THE
RAW-UNCALIBRATED GUIDANCE WHICH BRINGS STRONG CHANCES FOR BELOW-NORMAL
TEMPERATURES TO THIS SAME REGION. IN LIGHT OF THE STRONGER UNCALIBRATED
GUIDANCE, SLIGHTLY INCREASED CHANCES FOR BELOW-NORMAL TEMPERATURES REMAIN
FORECAST FOR SOUTHERN ALASKA. ACROSS THE NORTH SLOPE, THERE IS GOOD AGREEMENT
FOR ABOVE-NORMAL TEMPERATURES.
WITH NEGATIVE 500-HPA HEIGHT ANOMALIES PERSISTING ALONG THE WEST COAST,
ABOVE-NORMAL PRECIPITATION IS FAVORED FROM CENTRAL CALIFORNIA THROUGH MUCH OF
THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. ABOVE-NORMAL PRECIPITATION IS ALSO
SLIGHTLY FAVORED FOR MUCH OF THE GREAT PLAINS AND SOUTHEAST WHERE SOUTHERLY
FLOW AND A SHORTWAVE TROUGH MAY BRING ENHANCED PRECIPITATION. THE EUROPEAN
REFORECAST HIGHLIGHTS AN AREA IN EASTERN TEXAS AND LOUISIANA FOR THE BEST
CHANCES FOR ABOVE-NORMAL PRECIPITATION, WHILE THE GEFS AND CANADIAN REFORECAST
TOOLS ARE SLIGHTLY WEAKER; THEY REMAIN IN AGREEMENT FOR ABOVE-NORMAL
PRECIPITATION. IN THE NORTHEAST, NEAR TO BELOW-NORMAL PRECIPITATION IS FAVORED
WITH SLIGHTLY DRIER AIR BENEATH A 500-HPA RIDGE AND SLIGHT NORTHERLY FLOW
ALOFT. MEANWHILE, IN ALASKA, BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS MUCH
OF NORTHERN ALASKA AND SLIGHTLY INCREASED CHANCES FOR ABOVE-NORMAL
PRECIPITATION ARE FAVORED ACROSS SOUTHERN PARTS OF THE STATE WITH TROUGHING
RELOADING OVER THE GULF OF ALASKA BRINGING INCREASED ONSHORE FLOW.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 40% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
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: NEAR NORMAL, 3 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG THE DYNAMICAL TOOLS ACROSS THE EASTERN CONUS OFFSET BY
DIFFERENCES IN THE EVOLUTION OF NEGATIVE HEIGHT ANOMALIES ALONG THE WEST COAST..
8-14 DAY OUTLOOK FOR MAY 10 - 16 2023
THE 500-HPA HEIGHT PATTERN IS FORECAST TO BE LESS AMPLIFIED RELATIVE TO THE
6-10 DAY PERIOD BUT WITH A SIMILAR LONGWAVE PATTERN. AN AREA OF NEGATIVE
500-HPA HEIGHT ANOMALIES PERSISTS IN THE NORTHWESTERN ATLANTIC NEAR THE
CANADIAN MARITIME PROVINCES. POSITIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST
ACROSS MUCH OF NORTHERN NORTH AMERICA STRETCHING FROM THE NORTHERN TIER OF THE
CONUS INTO NORTHEAST ALASKA. ACROSS MUCH OF THE SOUTHERN CONUS NEAR TO SLIGHTLY
ABOVE-NORMAL 500-HPA HEIGHTS ARE FORECAST FOR WEEK-2. IN THE WESTERN CONUS,
NEGATIVE 500-HPA HEIGHT ANOMALIES AT THE ONSET OF THE PERIOD TRANSITION TO
ABOVE-NORMAL BY THE MIDDLE OF WEEK-2. WEAK NEGATIVE 500-HPA HEIGHT ANOMALIES
ARE FORECAST SOUTH OF ALASKA BRINGING SOUTHERLY FLOW TO ALASKA.
ACROSS MUCH OF THE UNITED STATES ABOVE-NORMAL TEMPERATURES ARE FAVORED DURING
THE WEEK-2 PERIOD. ABOVE-NORMAL TEMPERATURES ARE LIKELY ACROSS THE EASTERN
TWO-THIRDS OF THE CONUS DUE TO SLIGHTLY POSITIVE 500-HPA HEIGHT ANOMALIES
ACROSS THE REGION. ACROSS THE WESTERN THIRD OF THE CONUS, LINGERING NEGATIVE
500-HPA HEIGHT ANOMALIES WOULD BRING SLIGHTLY COOLER TEMPERATURES INCREASING
CHANCES FOR NEAR TO SLIGHTLY BELOW-NORMAL TEMPERATURES. IN ALASKA, ABOVE-NORMAL
TEMPERATURES ARE FAVORED ACROSS THE NORTHERN PORTIONS OF THE STATE. NEAR TO
SLIGHTLY BELOW-NORMAL TEMPERATURES ARE FAVORED IN THE SOUTHERN PORTIONS OF
ALASKA, WHERE THERE IS CONTINUED DISAGREEMENT BETWEEN THE REFORECAST TOOLS
WHICH SHOW NEAR-NORMAL TEMPERATURE CHANCES, AND THE UNCALIBRATED GUIDANCE WHICH
STRONGLY FAVOR BELOW-NORMAL TEMPERATURES.
THERE ARE WEAK CHANCES FOR ABOVE OR BELOW-NORMAL PRECIPITATION ACROSS MUCH OF
THE CONUS DURING THE WEEK-2 PERIOD. IN THE SOUTHERN PLAINS, GULF COAST, AND
FLORIDA THERE ARE HIGHER CHANCES FOR A SHORTWAVE TROUGH TO DEVELOP AND PROGRESS
THROUGH THE SOUTHERN CONUS, AND WITH ENHANCED MOISTURE FROM RETURN FLOW OFF THE
GULF OF MEXICO BRING INCREASED CHANCES FOR ABOVE-NORMAL PRECIPITATION. THE
LINGERING NEGATIVE 500-HPA HEIGHT ANOMALIES AT THE ONSET OF THE PERIOD OVER THE
WEST BRING REDUCED CHANCES FOR ABOVE-NORMAL PRECIPITATION RELATIVE TO THE 6-10
DAY PERIOD. IN THE NORTHEAST, NEAR-NORMAL PRECIPITATION CHANCES ARE FAVORED
BENEATH POSITIVE 500-HPA HEIGHT ANOMALIES AND SLIGHT NORTHERLY FLOW ALOFT. IN
ALASKA, BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS THE NORTH SLOPE UNDERNEATH
POSITIVE 500-HPA HEIGHT ANOMALIES. SLIGHTLY ABOVE-NORMAL PRECIPITATION IS
FAVORED IN SOUTHEAST AND SOUTH-CENTRAL ALASKA WHERE ONSHORE FLOW IS FORECAST.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 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 20%
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, DUE TO
FAIR AGREEMENT IN THE MID-LEVEL HEIGHT PATTERN AND TEMPERATURE TOOLS, OFFSET BY
LOW PROBABILITIES FOR PRECIPITATION CHANCES ACROSS THE UNITED STATES.
FORECASTER: RYAN BOLT
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 MAY
18.
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:
19710504 - 19560414 - 19730428 - 19540506 - 19510412
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:
19560413 - 19730430 - 19710503 - 19510411 - 19540506
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 08 - 12 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B A
SRN CALIF B N IDAHO B A NEVADA B A
W MONTANA N A E MONTANA N A WYOMING N A
UTAH B A ARIZONA B N COLORADO A N
NEW MEXICO A N 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 N
ILLINOIS A N MISSISSIPPI A A MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A A ALABAMA A A NEW YORK A N
VERMONT A B NEW HAMP A B MAINE A B
MASS A B CONN A B 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 B
AK ALEUTIAN B N AK WESTERN N N AK INT BSN N N
AK S INT B N AK SO COAST B A AK PNHDL N N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 10 - 16 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N N OREGON N A NRN CALIF B N
SRN CALIF B N IDAHO N A NEVADA B A
W MONTANA N A E MONTANA N A WYOMING N 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 N
ILLINOIS A N MISSISSIPPI A A MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS A N
PENN A N NEW JERSEY A N W VIRGINIA A N
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A N
AK ALEUTIAN B N AK WESTERN N N AK INT BSN N N
AK S INT B A AK SO COAST B A AK PNHDL N N
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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