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FXUS06 KWBC 051902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI MAY 05 2023
6-10 DAY OUTLOOK FOR MAY 11 - 15 2023
THE GFS, ECMWF, AND CANADIAN ENSEMBLE MEAN SOLUTIONS ARE IN FAIRLY GOOD
AGREEMENT ON THE 6-10 DAY MEAN 500-HPA HEIGHT FORECASTS ACROSS NORTH AMERICA
AND OCEANIC ENVIRONS. A DEEP TROUGH IS ANTICIPATED FROM THE WEST COAST OF
ALASKA SOUTHWARD ACROSS THE ALASKA PENINSULA AND GULF OF ALASKA. A MID-LEVEL
RIDGE IS DEPICTED ACROSS THE WESTERN HALF OF CANADA AND MUCH OF EASTERN ALASKA.
A TROUGH AND ACCOMPANYING NEGATIVE 500-HPA HEIGHT DEPARTURES ARE FORECAST OVER
THE ARCTIC OCEAN, WHICH MAY HAVE A MINOR INFLUENCE ON THE NORTH SLOPE OF
ALASKA. THE ENSEMBLE MEAN SOLUTIONS INDICATE THE BROAD CYCLONIC FLOW ON THE
SOUTHERN SIDE OF THE GULF OF ALASKA TROUGH ENDS UP SPLITTING INTO A NORTHERN
STREAM AND A SOUTHERN STREAM NEAR THE WEST COAST OF THE CONTIGUOUS U.S.
(CONUS). THE NORTHERN STREAM IS DIVERTED TOWARDS THE RIDGE OVER WESTERN CANADA
AND MUCH OF ALASKA, WHILE THE SOUTHERN STREAM IS DIVERTED INTO A TROUGH
ANTICIPATED OVER THE WESTERN CONUS. ONE SMALLER-SCALE FEATURE PREDICTED BY THE
ENSEMBLE MEANS IS A LOW-AMPLITUDE RIDGE OFF THE IMMEDIATE WEST COAST, NESTLED
IN-BETWEEN THE GULF OF ALASKA TROUGH AND THE WESTERN CONUS TROUGH. THE 0Z
DETERMINISTIC ECMWF AND 6Z DETERMINISTIC GFS RUNS PREDICT A MORE SIGNIFICANT
RIDGE EXTENDING INTO THE PACIFIC NORTHWEST. FARTHER DOWNSTREAM, A MID-LEVEL
RIDGE IS PREDICTED OVER THE EASTERN CONUS, AND WHERE THE NORTHERN AND SOUTHERN
STREAMS RECOMBINE, ANOTHER DEEP TROUGH IS FORECAST ACROSS THE CANADIAN
MARITIMES AND WESTERN ATLANTIC.
THERE ARE INCREASED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES FOR THE PACIFIC
NORTHWEST, MOST OF CALIFORNIA, NORTHERN AND CENTRAL PORTIONS OF THE
INTERMOUNTAIN REGION, AND FOR MOST AREAS EAST OF THE CONTINENTAL DIVIDE.
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES EXCEED 70% IN THE UPPER MISSISSIPPI
VALLEY AND PACIFIC NORTHWEST. THE EXPANSIVE AREA OF FAVORED ABOVE-NORMAL
TEMPERATURES IS WELL SUPPORTED BY THE TEMPERATURE CONSOLIDATION FORECAST, THE
CALIBRATED REFORECAST TEMPERATURES FROM THE GFS, ECMWF, AND CANADIAN ENSEMBLE
MEANS, AND THE AUTO-TEMPERATURE FORECAST. THIS IS CONSISTENT WITH THE
EXPECTATION OF MID-LEVEL RIDGING AND ABOVE-NORMAL 500-HPA HEIGHTS ACROSS THIS
BROAD REGION. ABOVE-NORMAL TEMPERATURES ARE ALSO INDICATED OVER NORTHEASTERN
PORTIONS OF ALASKA, PRIMARILY SUPPORTED BY THE CONSOLIDATION TOOL AND
REFORECAST TEMPERATURES FROM THE ENSEMBLE MEANS. NEAR-NORMAL 500-HPA HEIGHTS
AND THE PRESENCE OF A MID-LEVEL TROUGH FAVOR BELOW-NORMAL TEMPERATURES FOR
SOUTHEASTERN ARIZONA, NEW MEXICO, AND SOUTHWESTERN PORTIONS OF TEXAS. THERE ARE
ELEVATED CHANCES FOR BELOW-NORMAL TEMPERATURES FOR SOUTHWESTERN PARTS OF THE
ALASKA COAST, FROM THE SEWARD PENINSULA SOUTHWARD ACROSS THE ALASKA PENINSULA,
AND CONTINUING EASTWARD TO THE KENAI PENINSULA, NEAR A MID-LEVEL TROUGH.
THERE ARE ELEVATED CHANCES FOR ABOVE-NORMAL PRECIPITATION FOR PARTS OF SOUTHERN
CALIFORNIA, SOUTHERN AND EASTERN NEVADA, THE FOUR CORNER STATES, WYOMING, THE
GREAT PLAINS REGION, MUCH OF THE MISSISSIPPI VALLEY, THE LOWER OHIO VALLEY,
LOWER TENNESSEE VALLEY, ALABAMA, GEORGIA, AND FLORIDA. PROBABILITIES FOR
ABOVE-NORMAL PRECIPITATION EXCEED 60% IN NEW MEXICO AND PARTS OF WEST TEXAS.
THIS IS SUPPORTED BY THE AUTO AND CONSOLIDATION PRECIPITATION FORECASTS, AND
REFORECAST PRECIPITATION FROM THE ENSEMBLE MEANS. NEAR THE MID-LEVEL TROUGH
OVER THE GULF OF ALASKA, ABOVE-NORMAL PRECIPITATION IS PREDICTED FOR
SOUTH-CENTRAL AND PORTIONS OF SOUTHEAST ALASKA. ODDS FAVOR BELOW-NORMAL
PRECIPITATION FOR THE PACIFIC NORTHWEST AND PORTIONS OF NORTHERN CALIFORNIA
EASTWARD AND NORTHEASTWARD ACROSS WESTERN MONTANA, ASSOCIATED WITH THE
MID-LEVEL RIDGE AND WELL ABOVE-NORMAL 500-HPA HEIGHTS ANTICIPATED OVER THAT
REGION. ODDS MODESTLY FAVOR BELOW-NORMAL PRECIPITATION OVER PARTS OF THE
NORTHEAST AND MID-ATLANTIC REGION.
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 ON A SCALE OF
1-5. THIS IS DUE TO FAIRLY GOOD AGREEMENT AMONG THE VARIOUS MODELS AND TOOLS.
8-14 DAY OUTLOOK FOR MAY 13 - 19 2023
THE 500-HPA MEAN CIRCULATION PATTERN DURING WEEK-2 IS EXPECTED TO BE FAIRLY
SIMILAR TO THAT PREDICTED DURING THE 6-10 DAY FORECAST PERIOD, THOUGH WITH
ADJUSTMENTS NEEDED. THE RIDGE FORECAST OVER THE EASTERN CONUS DURING DAYS 6-10
IS EXPECTED TO QUICKLY DEAMPLIFY. A FLAT RIDGE ANTICIPATED ACROSS THE
SOUTH-CENTRAL AND SOUTHEASTERN CONUS REPRESENTS THE NORTHERN FLANK OF THE
SUBTROPICAL RIDGE. THE WEEK-2 MANUAL BLEND PREDICTS POSITIVE 500-HPA HEIGHT
ANOMALIES OF 30-50 METERS EAST OF THE MISSISSIPPI RIVER, AND A WESTWARD SHIFT
IN THE MARITIMES TROUGH, FOLLOWED BY DECREASING 500-HPA HEIGHTS EXPECTED OVER
THE NORTHEAST CONUS. IN CONTRAST, WEST OF THE MISSISSIPPI RIVER
MID-TROPOSPHERIC HEIGHTS ARE FORECAST TO RANGE FROM NEAR 30 METERS ABOVE
AVERAGE ACROSS THE SOUTHWEST TO 120-140 METERS ABOVE AVERAGE OVER THE PACIFIC
NORTHWEST, ASSOCIATED WITH THE RIDGE INDICATED OVER THE NORTHWESTERN CONUS. THE
NORTHERN PORTION OF THE MID-LEVEL RIDGE EXTENDS ACROSS MOST OF ALASKA,
ACCOMPANIED BY ABOVE-AVERAGE 500-HPA HEIGHTS.
ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE CONUS DURING WEEK-2, DUE
TO PREDICTED ABOVE-AVERAGE MID-TROPOSPHERIC HEIGHTS ASSOCIATED WITH MID-LEVEL
RIDGING, AND DEAMPLIFIED FLOW. THE REFORECAST CALIBRATED TEMPERATURE TOOLS,
CONSOLIDATED TEMPERATURE TOOL, BIAS-CORRECTED CANADIAN ENSEMBLE MEAN
TEMPERATURES, AND THE AUTO-TEMPERATURE FORECAST ARE IN GOOD AGREEMENT WITH THIS
PATTERN. THE BIAS-CORRECTED GEFS TEMPERATURES DIFFER SIGNIFICANTLY IN
FORECASTING NEAR TO BELOW-NORMAL TEMPERATURES ACROSS MUCH OF THE SOUTHERN AND
INTERIOR EASTERN CONUS, AND ARE THOUGHT TO BE TOO COOL. MOST OF THE DYNAMICAL
GUIDANCE SUPPORTS BELOW-NORMAL TEMPERATURES FOR MUCH OF THE SOUTHERN ROCKIES
AND SOUTHERN PLAINS, AND FROM ALASKA’S SEWARD PENINSULA SOUTHWARD ACROSS THE
ALASKA PENINSULA, AND CONTINUING EASTWARD OVER SOUTH-CENTRAL ALASKA.
DURING WEEK-2, THERE ARE ELEVATED CHANCES FOR ABOVE-NORMAL PRECIPITATION FOR
MUCH OF CALIFORNIA, NEVADA, THE FOUR-CORNERS STATES, SOUTHERN PORTIONS OF IDAHO
AND WYOMING, THE CENTRAL HIGH PLAINS, THE SOUTHERN GREAT PLAINS, THE LOWER
MISSISSIPPI VALLEY, THE UPPER OHIO VALLEY AND MOST OF THE TENNESSEE VALLEY, THE
CENTRAL AND SOUTHERN APPALACHIANS, AND FROM THE SOUTHERN MID-ATLANTIC REGION TO
FLORIDA. WESTERN PORTIONS OF THE AREA OF FAVORED ABOVE-NORMAL PRECIPITATION IS
ATTRIBUTED TO THE PROXIMITY OF A MID-LEVEL TROUGH. FOR CENTRAL AND EASTERN
PORTIONS OF THE CONUS, AMPLE GULF AND ATLANTIC MOISTURE IS EXPECTED TO STREAM
NORTHWARD AHEAD OF A COLD FRONT AS IT TRAVERSES THE REGION, RESULTING IN
WIDESPREAD PRECIPITATION. ABOVE-NORMAL PRECIPITATION IS ALSO FAVORED OVER
PARTS OF THE SOUTHERN ALASKA COAST, ASSOCIATED WITH A MID-LEVEL TROUGH AND
CYCLONIC ACTIVITY. ODDS ARE TILTED TOWARDS BELOW-NORMAL PRECIPITATION FROM THE
PACIFIC NORTHWEST AND NORTHERN INTERMOUNTAIN REGION EASTWARD ACROSS THE
NORTHERN ROCKIES, NORTHERN PLAINS, AND UPPER MISSISSIPPI VALLEY. THIS IS BASED
ON THE PRECIPITATION CONSOLIDATION TOOL, SOME OF THE REFORECAST AND
BIAS-CORRECTED PRECIPITATION TOOLS, AND IS CONSISTENT WITH THE PREDICTED
PRESENCE OF A MID-LEVEL RIDGE AND ABOVE-AVERAGE 500-HPA HEIGHTS.
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 ON A
SCALE OF 1-5, DUE TO FAIR AGREEMENT AMONG THE VARIOUS 500-HPA HEIGHT MODELS AND
TEMPERATURE AND PRECIPITATION 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:
19830421 - 19770509 - 19710502 - 19800508 - 19980510
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:
19770508 - 19710422 - 19830421 - 19980508 - 19710501
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 11 - 15 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A N
SRN CALIF A N IDAHO A B NEVADA A N
W MONTANA A B E MONTANA A A WYOMING A A
UTAH N A ARIZONA N A COLORADO N A
NEW MEXICO B A N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS N A S TEXAS N A W TEXAS B 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 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 N DELAWARE A B VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A N
AK ALEUTIAN B N AK WESTERN B N AK INT BSN N N
AK S INT N A AK SO COAST B A AK PNHDL N N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 13 - 19 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A A
SRN CALIF A N IDAHO A N NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A N
UTAH A A ARIZONA N A COLORADO N A
NEW MEXICO B A N DAKOTA A B S DAKOTA A N
NEBRASKA A N KANSAS A N OKLAHOMA N A
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA A B IOWA A N MISSOURI A N
ARKANSAS A A LOUISIANA N 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 A
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 N
AK ALEUTIAN N N AK WESTERN B N AK INT BSN N N
AK S INT B N AK SO COAST B N AK PNHDL A 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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