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FXUS06 KWBC 091902
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 09 2023
6-10 DAY OUTLOOK FOR MAY 15 - 19 2023
DYNAMICAL MODELS ARE IN GOOD AGREEMENT REGARDING AN AMPLIFIED 500-HPA
GEOPOTENTIAL HEIGHT PATTERN ACROSS THE FORECAST DOMAIN DURING THE 6-10 DAY
PERIOD. AT THE OUTSET OF THE PERIOD, EXPANSIVE RIDGING AND ASSOCIATED POSITIVE
HEIGHT ANOMALIES ARE FORECAST ACROSS MUCH OF WESTERN AND CENTRAL NORTH AMERICA,
INCLUDING ALASKA. HOWEVER, THE PREDICTED PROPAGATION OF THE MADDEN JULIAN
OSCILLATION (MJO) INTO PHASES 7 AND 8 SUPPORT A RETROGRESSION OF THE TROUGHING
OVER EASTERN CANADA AND CLOSER TO NORMAL MID-LEVEL HEIGHTS EAST OF THE ROCKIES
LATER IN THE PERIOD, WITH THE RIDGE BECOMING MORE FOCUSED NEAR THE WEST COAST.
A REX BLOCK IS LIKELY TO FORM WITH TROUGHING DEVELOPING UNDERNEATH THE RIDGE
AXIS FAVORING ENHANCED CYCLONIC FLOW ACROSS PARTS OF THE SOUTH-CENTRAL AND
SOUTHWESTERN CONUS. TODAY’S MANUAL 500-HPA HEIGHT BLEND FOR THE PERIOD AS A
WHOLE DEPICTS ABOVE NORMAL HEIGHTS ACROSS MUCH OF THE WESTERN HALF OF THE
CONUS, ALONG WITH ALASKA. NEAR NORMAL HEIGHTS ARE DEPICTED ACROSS MUCH OF THE
EASTERN AND SOUTHERN TIER OF THE CONUS, WITH BELOW NORMAL HEIGHTS FAVORED
ACROSS THE GREAT LAKES AND NORTHEAST.
EARLY IN THE PERIOD, DAILY RECORD HIGH TEMPERATURES ARE POSSIBLE ACROSS THE
PACIFIC NORTHWEST UNDERNEATH AMPLIFIED RIDGING, WITH THE NATIONAL BLEND OF
MODELS INDICATING TEMPERATURES OVER SOME LOW ELEVATION AREAS EXCEEDING 90 DEG F
ON MAY 15. WHILE SOME MODERATION IS FORECAST LATER IN THE PERIOD, THE OVERALL
PATTERN SUPPORTS HIGH PROBABILITIES (GREATER THAN 80 PERCENT) FOR ABOVE-NORMAL
TEMPERATURES ACROSS PARTS OF THE PACIFIC NORTHWEST AND GREAT BASIN, WITH
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES REMAINING ELEVATED THROUGHOUT MUCH
OF THE WEST AND NORTHERN PLAINS, AS WELL AS PARTS OF THE UPPER MISSISSIPPI
VALLEY. THE PATTERN IN THE EAST IS FORECAST TO BE MORE TRANSITIONAL, AS
TROUGHING INCREASES THROUGHOUT THE PERIOD. THE HIGHEST PROBABILITIES FOR
BELOW-NORMAL TEMPERATURES ARE FORECAST ACROSS THE SOUTHERN PLAINS DUE TO
ENHANCED RAINFALL FORECAST BEFORE AND DURING THE FORECAST PERIOD. ENHANCED
CHANCES FOR BELOW-NORMAL TEMPERATURES ARE ALSO DEPICTED ACROSS PARTS OF THE
MIDDLE AND LOWER MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, GREAT LAKES, AND
INTERIOR NORTHEAST. PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE ELEVATED
ACROSS PARTS OF THE SOUTHERN MID-ATLANTIC AND SOUTHEAST TIED TO RELATIVELY
WARMER TEMPERATURES FORECAST EARLY IN THE PERIOD. RIDGING ACROSS ALASKA
GENERALLY SUPPORTS ENHANCED PROBABILITIES FOR NEAR- TO ABOVE-NORMAL
TEMPERATURES ACROSS THE STATE, WITH THE EXCEPTION OF PARTS OF THE SOUTHWESTERN
AND SOUTH-CENTRAL MAINLAND WHERE BELOW-NORMAL TEMPERATURES ARE FAVORED DUE TO
INCREASED CLOUD COVER AND PRECIPITATION CHANCES, ALONG WITH REMAINING SNOW
COVER OVER SOME AREAS.
RIDGING FAVORS INCREASED PROBABILITIES OF BELOW-NORMAL PRECIPITATION ACROSS
PARTS OF THE NORTHWEST CONUS AND EXTENDING THROUGH THE NORTH-CENTRAL CONUS AND
MIDWEST. AN ANOMALOUS CYCLONIC MID-LEVEL CIRCULATION IS FORECAST TO DEVELOP
UNDERNEATH THE RIDGE AXIS, ACROSS NORTHERN MEXICO OR THE EASTERN PACIFIC SOUTH
OF CALIFORNIA, WHICH FAVORS INCREASING CHANCES FOR PRECIPITATION ACROSS
CLIMATOLOGICALLY DRY AREAS OF THE SOUTHWESTERN CONUS. THIS IN TURN FAVORS HIGH
PROBABILITIES OF ABOVE-NORMAL PRECIPITATION OVER THESE AREAS (GREATER THAN 70
PERCENT OVER PARTS OF ARIZONA AND WESTERN NEW MEXICO), WITH ELEVATED
PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION EXTENDING THROUGH THE SOUTHERN
PLAINS, LOWER MISSISSIPPI VALLEY, SOUTHERN MID-ATLANTIC, AND SOUTHEAST AS
SOUTHERLY FLOW AND MOISTURE ADVECTION INCREASE AHEAD OF BUILDING TROUGHING IN
THE EAST. WEAK TROUGHING FORECAST OVER THE BERING SEA FAVORS ELEVATED
PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION ACROSS MOST OF MAINLAND ALASKA AND
THE ALEUTIANS, WITH THE EXCEPTION OF PARTS OF SOUTHEAST ALASKA WHERE
PROBABILITIES FOR BELOW-NORMAL PRECIPITATION ARE INCREASED.
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
GOOD MODEL AGREEMENT REGARDING AN AMPLIFIED PATTERN ACROSS NORTH AMERICA,
OFFSET BY SOME TRANSITION ACROSS THE EAST.
8-14 DAY OUTLOOK FOR MAY 17 - 23 2023
THE 500-HPA HEIGHT PATTERN DURING WEEK-2 IS SIMILAR TO THAT OF THE 6-10 DAY
PERIOD, WITH A SLIGHT RETROGRESSION OF THE MID-LEVEL FEATURES. THIS RESULTS IN
A LARGELY PERSISTENT AND SIMILAR FORECAST. RIDGING REMAINS FAVORED ACROSS
WESTERN NORTH AMERICA, WITH TROUGHING PREDICTED OVER EASTERN CANADA. THE WEEK-2
MANUAL HEIGHT BLEND DEPICTS ABOVE-NORMAL HEIGHTS ACROSS THE WEST AND EXTENDING
THROUGH ALASKA, AND NEAR- TO BELOW-NORMAL HEIGHTS ACROSS MUCH OF THE EAST. THE
LARGEST NEGATIVE HEIGHT ANOMALIES ARE PREDICTED ACROSS EASTERN CANADA, WITH
SLIGHTLY BELOW-NORMAL HEIGHTS EXTENDING INTO THE UPPER MISSISSIPPI VALLEY,
GREAT LAKES, AND NORTHEAST.
INCREASED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES CONTINUE TO BE FORECAST
ACROSS MUCH OF THE WESTERN CONUS UNDERNEATH ANOMALOUS RIDGING. CONVERSELY,
PROBABILITIES FOR BELOW-NORMAL TEMPERATURES ARE ELEVATED ACROSS THE SOUTHERN
PLAINS DUE TO INCREASED PRECIPITATION FORECAST. THE TROUGHING OVER EASTERN
CANADA SUPPORTS ELEVATED CHANCES OF BELOW-NORMAL TEMPERATURES ACROSS THE
EAST-CENTRAL CONUS WITH MULTIPLE SHORTWAVES AND FRONTAL SYSTEMS POSSIBLY MOVING
ACROSS THE REGION. ENHANCED CHANCES OF ABOVE-NORMAL TEMPERATURES ARE FORECAST
ACROSS THE EASTERN SEABOARD UNDERNEATH MORE SOUTHERLY MID-LEVEL FLOW AND DUE TO
THE UPSTREAM TROUGH SLIGHTLY RETROGRADING. PROBABILITIES FOR ABOVE-NORMAL
TEMPERATURES ARE INCREASED ACROSS SOUTHEAST ALASKA AND MUCH OF NORTHERN AND
EASTERN MAINLAND ALASKA, CONSISTENT WITH THE ECMWF AND GEFS REFORECAST TOOLS,
AND POSITIVE HEIGHT ANOMALIES. DESPITE HIGHER HEIGHTS, INCREASED ONSHORE FLOW
FAVORS ENHANCED CHANCES FOR NEAR- TO BELOW-NORMAL TEMPERATURES ACROSS
SOUTHWESTERN ALASKA.
INCREASED PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION REMAIN FAVORED ACROSS
MUCH OF THE SOUTHWEST AND SOUTHERN PLAINS TIED TO THE AFOREMENTIONED CYCLONIC
CIRCULATION PREDICTED UNDERNEATH THE RIDGING TO THE NORTH. OCCASIONAL FRONTAL
SYSTEMS ROTATING THROUGH THE TROUGHING IN THE EAST FAVOR ELEVATED CHANCES OF
ABOVE-NORMAL PRECIPITATION ACROSS THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS,
THE SOUTHERN MID-ATLANTIC, AND SOUTHEAST. ANOMALOUS NORTHERLY MID-LEVEL FLOW
FAVORS INCREASED CHANCES FOR BELOW-NORMAL PRECIPITATION ACROSS MUCH OF THE
NORTHERN TIER OF THE CONUS, WITH THE HIGHEST PROBABILITIES ACROSS THE PACIFIC
NORTHWEST, COINCIDING WITH THE LARGEST POSITIVE MID-LEVEL HEIGHT ANOMALIES, AND
THE UPPER MIDWEST, SUPPORTED BY TELECONNECTION ANALYSIS WITH THE NEGATIVE
HEIGHT ANOMALY CENTER OVER EASTERN CANADA. ELEVATED NEAR- TO ABOVE-NORMAL
PRECIPITATION PROBABILITIES REMAIN FORECAST ACROSS MUCH OF MAINLAND ALASKA AND
THE ALEUTIANS DUE TO CONTINUED ENHANCED SOUTHERLY FLOW. INCREASED CHANCES FOR
BELOW NORMAL PRECIPITATION ARE FORECAST ACROSS SOUTHEAST ALASKA, CLOSER TO THE
MEAN RIDGE AXIS.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 30% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 5% OF TODAY'S OPERATIONAL 6Z GFS 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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
A GENERALLY PERSISTENT FORECAST FROM THE 6-10 DAY PERIOD, OFFSET BY DECREASING
AMPLIFICATION AND SOME SMALL DIFFERENCES IN THE FORECAST TOOLS, PARTICULARLY
OVER THE EASTERN U.S.
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 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:
19510502 - 19750502 - 19750507 - 19890425 - 19770510
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:
19510502 - 19750506 - 19890425 - 19940518 - 19980518
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 15 - 19 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A N NRN CALIF A A
SRN CALIF A A IDAHO A N NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A N
UTAH A A ARIZONA A A COLORADO B A
NEW MEXICO B A N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS B B OKLAHOMA B N
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA A B IOWA N B MISSOURI N B
ARKANSAS B N LOUISIANA B A WISCONSIN N B
ILLINOIS B B MISSISSIPPI N A MICHIGAN B N
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE N B ALABAMA N A NEW YORK B N
VERMONT B N NEW HAMP N N MAINE N N
MASS N N CONN N N RHODE IS N N
PENN B B NEW JERSEY N N W VIRGINIA B B
MARYLAND N N DELAWARE N N VIRGINIA N N
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN N N AK WESTERN N A AK INT BSN A A
AK S INT N N AK SO COAST N N AK PNHDL A B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 17 - 23 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A N NRN CALIF A A
SRN CALIF A A IDAHO A A NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A A
UTAH A A ARIZONA A A COLORADO B A
NEW MEXICO B A N DAKOTA N B S DAKOTA N B
NEBRASKA N B KANSAS B N OKLAHOMA B A
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA B B IOWA N B MISSOURI B N
ARKANSAS B A LOUISIANA B A WISCONSIN B B
ILLINOIS B B MISSISSIPPI B A MICHIGAN B N
INDIANA B N OHIO B N KENTUCKY B N
TENNESSEE B A ALABAMA N A NEW YORK N N
VERMONT N N NEW HAMP N N MAINE N N
MASS A N CONN A N RHODE IS A N
PENN N N NEW JERSEY A N W VIRGINIA N N
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE N A
AK ALEUTIAN N N AK WESTERN B N AK INT BSN A A
AK S INT N N AK SO COAST N N AK PNHDL A B
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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