498
FXUS06 KWBC 111917
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU MAY 11 2023
6-10 DAY OUTLOOK FOR MAY 17 - 21 2023
DYNAMICAL MODELS ARE IN FAIRLY 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 NORTH AMERICA. 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 SOUTHWESTERN CONUS. CONSIDERABLE UNCERTAINTY REMAINS OVER
THE ALASKA DOMAIN WITH SOME SOLUTIONS (0Z CANADIAN ENSEMBLE MEAN AND THE 0Z
DETERMINISTIC GFS RUN) PREDICT RIDGING, WHEREAS MOST OTHER SOLUTIONS FAVOR
TROUGHING. 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
EASTERN 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 AT LEAST A 90 PERCENT CHANCE FOR ABOVE-NORMAL TEMPERATURES
INDICATED ACROSS EASTERN OREGON. PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES
REMAIN ELEVATED THROUGHOUT MUCH OF THE WEST, THE NORTHERN HALF OF THE PLAINS,
AND PORTIONS OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY. THE HIGHEST
PROBABILITIES FOR BELOW-NORMAL TEMPERATURES (GREATER THAN 50 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 MUCH OF THE GREAT LAKES REGION, PARTS OF THE EASTERN
CORN BELT, OHIO VALLEY, NORTHERN AND CENTRAL APPALACHIANS, AND MOST OF THE
ATLANTIC COASTAL PLAIN FROM NORTHERN VIRGINIA TO MAINE. 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 ANALOG GUIDANCE. PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE
ELEVATED FROM PARTS OF THE LOWER MISSISSIPPI VALLEY EASTWARD ACROSS THE
SOUTHERN ATLANTIC STATES, EXPECTED AHEAD OF THE LARGE EASTERN NORTH AMERICAN
TROUGH. POSITIVE HEIGHT ANOMALIES GENERALLY SUPPORT ENHANCED PROBABILITIES FOR
NEAR- TO ABOVE-NORMAL TEMPERATURES ACROSS SOUTHEAST ALASKA AND PARTS OF 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,
MIDWEST, SOUTHERN GREAT LAKES REGION, AND OHIO VALLEY. 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 EASTERN ARIZONA
AND WESTERN NEW MEXICO). CONTINUING EASTWARD, THOUGH NOW WITH THE INCREASING
INFLUENCE OF THE EASTERN CONUS TROUGH AND INFLOWING GULF MOISTURE,
PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION REMAIN ELEVATED ACROSS THE CENTRAL
AND SOUTHERN PLAINS, THE LOWER MISSISSIPPI VALLEY, AND THE SOUTHERN ATLANTIC
COAST FROM NORTH CAROLINA TO FLORIDA. WEAK TROUGHING CENTERED NEAR THE WEST
COAST OF ALASKA AND A BROAD AREA OF ONSHORE FLOW FAVORS ELEVATED PROBABILITIES
FOR ABOVE-NORMAL PRECIPITATION FOR MOST OF ALASKA.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 33% 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
FAIRLY GOOD MODEL AGREEMENT REGARDING AN AMPLIFIED PATTERN ACROSS NORTH
AMERICA, OFFSET BY DIFFERENCES AMONG THE SURFACE TEMPERATURE AND PRECIPITATION
TOOLS.
8-14 DAY OUTLOOK FOR MAY 19 - 25 2023
THE 500-HPA HEIGHT PATTERN DURING WEEK-2 IS SIMILAR TO THAT OF THE 6-10 DAY
PERIOD, WITH DE-AMPLIFICATION OF THE MID-LEVEL FEATURES. THIS RESULTS IN A
LARGELY PERSISTENT AND SIMILAR FORECAST. RIDGING REMAINS FAVORED ACROSS MUCH OF
WESTERN NORTH AMERICA, WITH TROUGHING PREDICTED OVER EASTERN CANADA AND
PORTIONS OF THE EASTERN CONUS. THE WEEK-2 MANUAL HEIGHT BLEND DEPICTS
ABOVE-NORMAL HEIGHTS ACROSS THE WEST AND EXTENDING THROUGH ALASKA, AND NEAR-
NORMAL HEIGHTS ACROSS MUCH OF THE EAST. THE LARGEST NEGATIVE HEIGHT ANOMALIES
ARE PREDICTED ACROSS EASTERN CANADA, WITH SLIGHTLY BELOW-NORMAL HEIGHTS
EXTENDING SOUTHWARD INTO NORTHERN NEW ENGLAND.
INCREASED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES CONTINUE TO BE FORECAST
ACROSS MUCH OF THE WESTERN AND NORTH-CENTRAL CONUS UNDERNEATH ANOMALOUS
RIDGING. PROBABILITIES OF ABOVE-NORMAL TEMPERATURES EXCEED 80 PERCENT OVER
EASTERN OREGON, SOUTHEASTERN WASHINGTON, AND WESTERN IDAHO. CONVERSELY,
PROBABILITIES FOR BELOW-NORMAL TEMPERATURES ARE ELEVATED ACROSS THE SOUTHERN
PLAINS DUE TO INCREASED PRECIPITATION FORECAST. THE TROUGHING OVER EASTERN
NORTH AMERICA SUPPORTS ELEVATED CHANCES OF BELOW-NORMAL TEMPERATURES OVER
MICHIGAN, AND NEAR-NORMAL TEMPERATURES OVER MOST OF THE EASTERN CONUS, WHICH
REPRESENTS A COMPROMISE BETWEEN VARIOUS COMPETING TOOLS. ENHANCED CHANCES OF
ABOVE-NORMAL TEMPERATURES ARE FORECAST ACROSS FLORIDA, SOUTHEASTERN GEORGIA AND
ADJACENT PARTS OF SOUTH CAROLINA, GENERALLY SUPPORTED BY THE BIAS-CORRECTED AND
CALIBRATED REFORECAST TEMPERATURE TOOLS, THE CONSOLIDATION TOOL, AND THE
AUTOMATED TEMPERATURE FORECAST. PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE
INCREASED SLIGHTLY OVER THE NEW ENGLAND COAST AND LONG ISLAND, ANTICIPATED JUST
EAST OF A MEAN TROUGH AXIS. THE MEAN TROUGH PREDICTED OVER ALASKA FAVORS
BELOW-NORMAL TEMPERATURES SOUTH OF THE BROOKS RANGE.
INCREASED PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION REMAIN FAVORED FROM MOST
OF CALIFORNIA AND THE CENTRAL AND SOUTHERN INTERMOUNTAIN REGION EASTWARD ACROSS
THE CENTRAL AND SOUTHERN ROCKIES, THE CENTRAL HIGH PLAINS, THE ENTIRE SOUTHERN
PLAINS REGION, THE LOWER MISSISSIPPI VALLEY, SOUTHERN TENNESSEE, THE GULF COAST
STATES, AND THE ATLANTIC COAST STATES FROM FLORIDA TO SOUTHERN VIRGINIA. THIS
IS BASED ON EXPECTED SOUTHERLY FLOW AND INCREASING MOISTURE ADVECTION
ASSOCIATED WITH THE SOUTHWESTERN AND EASTERN CONUS MID-LEVEL TROUGHS.
PROBABILITIES OF ABOVE-NORMAL PRECIPITATION EXCEED 60 PERCENT OVER PORTIONS OF
THE FOUR CORNERS REGION. ANOMALOUS NORTHERLY MID-LEVEL FLOW AND/OR WELL
ABOVE-AVERAGE 500-HPA HEIGHTS FAVOR INCREASED CHANCES FOR BELOW-NORMAL
PRECIPITATION FROM THE PACIFIC NORTHWEST EASTWARD ACROSS MUCH OF MONTANA AND
THE NORTHERN PLAINS, EASTERN NEBRASKA, THE UPPER AND MIDDLE MISSISSIPPI VALLEY,
PORTIONS OF THE OHIO VALLEY, AND ALL BUT EASTERNMOST PORTIONS OF THE GREAT
LAKES REGION. ELEVATED NEAR- TO ABOVE-NORMAL PRECIPITATION PROBABILITIES REMAIN
FORECAST ACROSS MOST OF MAINLAND AND SOUTHEAST ALASKA, DUE TO THE PROXIMITY OF
A MID-LEVEL TROUGH AND INCREASED ONSHORE FLOW. A RELATIVELY SMALL AREA OF
FAVORED BELOW-NORMAL PRECIPITATION IS INDICATED OVER THE EXTREME SOUTHWEST PART
OF THE MAINLAND, KODIAK ISLAND, AND THE EASTERN ALASKA PENINSULA.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 33% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: NEAR-AVERAGE, 3 OUT OF 5, DUE TO A
GENERALLY PERSISTENT FORECAST FROM THE 6-10 DAY PERIOD, OFFSET BY A
DEAMPLIFYING FLOW PATTERN AND SOME DIFFERENCES IN THE FORECAST TOOLS.
FORECASTER: ANTHONY A
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:
19750508 - 19510502 - 19570502 - 19820517 - 19760426
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:
19750508 - 19940521 - 19510503 - 19570430 - 19760425
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 17 - 21 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B 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 A A
NEW MEXICO B A N DAKOTA A B S DAKOTA A N
NEBRASKA A N KANSAS A A OKLAHOMA B A
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA A N IOWA A N MISSOURI N N
ARKANSAS N A LOUISIANA N A WISCONSIN N N
ILLINOIS N N MISSISSIPPI N A MICHIGAN B N
INDIANA B N OHIO B N KENTUCKY B N
TENNESSEE N N ALABAMA A A NEW YORK B N
VERMONT B N NEW HAMP B N MAINE B N
MASS B N CONN B N RHODE IS N N
PENN B N NEW JERSEY B N W VIRGINIA B N
MARYLAND B N DELAWARE N N VIRGINIA B N
N CAROLINA N A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B N AK INT BSN N A
AK S INT B A AK SO COAST B A AK PNHDL A N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 19 - 25 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 A
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO N A N DAKOTA A B S DAKOTA A N
NEBRASKA A N KANSAS N A OKLAHOMA B A
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA N N IOWA A N MISSOURI N N
ARKANSAS N A LOUISIANA N A WISCONSIN N N
ILLINOIS N N MISSISSIPPI N A MICHIGAN B N
INDIANA N N OHIO N N KENTUCKY N N
TENNESSEE N N 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 N
N CAROLINA N A S CAROLINA N A GEORGIA N A
FL PNHDL A A FL PENIN A A AK N SLOPE N N
AK ALEUTIAN N N AK WESTERN B N AK INT BSN B N
AK S INT B N 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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