956
FXUS06 KWBC 101902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED MAY 10 2023
6-10 DAY OUTLOOK FOR MAY 16 - 20 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 SUPPORTS 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 OVER THE WEST. 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.
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, NORTHERN HALF OF THE PLAINS, AND PARTS OF THE
UPPER MISSISSIPPI VALLEY. THE HIGHEST PROBABILITIES FOR BELOW-NORMAL
TEMPERATURES (GREATER THAN 60 PERCENT) 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 NORTHEAST. WHILE THE ECMWF REFORECAST TOOL IS SUBSTANTIALLY WARMER COMPARED
TO THE GEFS REFORECAST TOOL, ESPECIALLY ACROSS THE MIDDLE MISSISSIPPI AND
TENNESSEE VALLEYS, A TILT TOWARD A COOLER SOLUTION WAS PREFERRED DUE TO THE
WELL-DEFINED TROUGH AXIS AND SUPPORT FROM THE ANALOGUE GUIDANCE. 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. POSITIVE HEIGHT ANOMALIES GENERALLY SUPPORT ENHANCED
PROBABILITIES FOR NEAR- TO ABOVE-NORMAL TEMPERATURES ACROSS SOUTHEAST ALASKA
AND THE EASTERN AND NORTHERN MAINLAND. CHANCES FOR BELOW-NORMAL TEMPERATURES
ARE INCREASED OVER THE SOUTHWESTERN AND SOUTH-CENTRAL MAINLAND 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 TROUGHING IN THE EAST.
WEAK TROUGHING FORECAST OVER THE BERING SEA EARLY IN THE PERIOD FAVORS ELEVATED
PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION ACROSS MOST OF MAINLAND ALASKA,
WITH PROBABILITIES FOR BELOW-NORMAL PRECIPITATION INCREASED OVER SOUTHEAST
ALASKA.
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 DIFFERENCES IN THE TEMPERATURE REFORECAST TOOLS IN THE EAST.
8-14 DAY OUTLOOK FOR MAY 18 - 24 2023
THE 500-HPA HEIGHT PATTERN DURING WEEK-2 IS SIMILAR TO THAT OF THE 6-10 DAY
PERIOD, WITH SOME DE-AMPLIFICATION 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
500-HPA HEIGHT BLEND DEPICTS ABOVE-NORMAL HEIGHTS ACROSS THE WEST AND EXTENDING
THROUGH ALASKA, AND NEAR- TO BELOW-NORMAL HEIGHTS ACROSS MUCH OF THE EAST (WITH
THE EXCEPTION OF FAR EASTERN NEW ENGLAND WHERE SLIGHTLY ABOVE-NORMAL HEIGHTS
ARE INDICATED). THE LARGEST NEGATIVE HEIGHT ANOMALIES ARE PREDICTED ACROSS
EASTERN CANADA, WITH SLIGHTLY BELOW-NORMAL HEIGHTS EXTENDING INTO THE UPPER
MISSISSIPPI VALLEY, GREAT LAKES, AND INTERIOR 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 NEAR- TO ABOVE-NORMAL TEMPERATURES ARE
FORECAST ACROSS THE EASTERN SEABOARD UNDERNEATH MORE SOUTHERLY MID-LEVEL FLOW
AND DUE TO THE UPSTREAM TROUGH. PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE
INCREASED ACROSS PARTS OF SOUTHEAST ALASKA AND NORTHERN MAINLAND ALASKA,
CONSISTENT WITH THE REFORECAST CONSOLIDATION TOOL AND POSITIVE MID-LEVEL HEIGHT
ANOMALIES. WEAK TROUGHING MAY SHIFT FROM THE BERING SEA TO WESTERN ALASKA
FAVORING RELATIVELY WEAKER POSITIVE HEIGHT ANOMALIES COMPARED TO THE REST OF
THE STATE, AND ENHANCED CHANCES FOR NEAR- TO BELOW-NORMAL TEMPERATURES ACROSS
SOUTHWESTERN AND SOUTH-CENTRAL 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, WITH THE GEFS AND
CANADIAN ENSEMBLES INDICATING A FURTHER NORTHWARD EXTENSION OF THE HEAVY
PRECIPITATION POTENTIAL INTO THE GREAT BASIN. 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 PARTS OF SOUTHEAST ALASKA,
CLOSER TO THE MEAN RIDGE AXIS.
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: 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.
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 - 19760426 - 19750508 - 19820516 - 19890425
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 - 19750507 - 19940520 - 19890426 - 19760425
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 16 - 20 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 N E MONTANA A B WYOMING A A
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO B A N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS N N OKLAHOMA B A
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA N B IOWA A B MISSOURI B B
ARKANSAS B A LOUISIANA B A WISCONSIN B B
ILLINOIS B B MISSISSIPPI N A MICHIGAN B B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE B N ALABAMA N A NEW YORK B N
VERMONT B N NEW HAMP B N MAINE B 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 B A AK INT BSN A A
AK S INT B A AK SO COAST B N AK PNHDL A B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 18 - 24 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 N E MONTANA A N WYOMING A A
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO B A N DAKOTA A B S DAKOTA A B
NEBRASKA A N KANSAS N A OKLAHOMA B A
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA N B IOWA N B MISSOURI B N
ARKANSAS B A LOUISIANA B A WISCONSIN B B
ILLINOIS B B MISSISSIPPI B A MICHIGAN B B
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 N N CONN N N RHODE IS N N
PENN N N NEW JERSEY N N W VIRGINIA N N
MARYLAND N N DELAWARE N N VIRGINIA N A
N CAROLINA N A S CAROLINA A A GEORGIA N 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 N A
AK S INT B A AK SO COAST B N 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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