963
FXUS06 KWBC 121902
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 12 2023
6-10 DAY OUTLOOK FOR MAY 18 - 22 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. THE PRIMARY LONGWAVE FEATURES INCLUDE A RIDGE AND WELL ABOVE-AVERAGE
500-HPA HEIGHTS FOR THE NORTHWESTERN CONUS AND WESTERN CANADA, UNDERCUT BY A
WEAK TROUGH CENTERED OVER NORTHERN BAJA AND FAR SOUTHERN CALIFORNIA, A TROUGH
OVER ALASKA AND MUCH OF THE EASTERN PACIFIC, AND ANOTHER TROUGH OVER EASTERN
NORTH AMERICA. THE EASTERN NORTH AMERICAN TROUGH IS FULL-LATITUDE AND EXTENDS
FROM THE ARCTIC OCEAN SOUTHWARD ACROSS EASTERN CANADA AND THE EASTERN CONUS;
HOWEVER, MID-LEVEL HEIGHTS OVER THE EASTERN CONUS ARE PREDICTED TO BE NEAR TO
ONLY SLIGHTLY-BELOW NORMAL WITH THE GREATEST NEGATIVE HEIGHT DEPARTURES
FORECAST NORTH OF THE U.S.-CANADIAN BORDER. THE 06Z DETERMINISTIC GFS SOLUTION
DIFFERS IN THAT IT EXTENDS THE WESTERN NORTH AMERICAN RIDGE NORTHWESTWARD OVER
ALL BUT SOUTHWESTERN PORTIONS OF ALASKA.
THE OVERALL PATTERN SUPPORTS ELEVATED PROBABILITIES FOR ABOVE-NORMAL
TEMPERATURES FROM MOST AREAS WEST OF THE CONTINENTAL DIVIDE EASTWARD ACROSS THE
NORTHERN HIGH PLAINS. THE HIGHEST PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES
(IN EXCESS OF 80 PERCENT) ARE INDICATED FROM THE PACIFIC NORTHWEST AND
NORTHEASTERN CALIFORNIA EASTWARD ACROSS NORTHERN AND CENTRAL PORTIONS OF THE
INTERMOUNTAIN REGION. ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED FROM FLORIDA
NORTHEASTWARD TO PARTS OF SOUTH CAROLINA, SUPPORTED BY THE TEMPERATURE
CONSOLIDATION FORECAST AND THE GFS AND ECMWF CALIBRATED REFORECAST
TEMPERATURES. THIS IS ALSO CONSISTENT WITH SOUTHERLY FLOW EXPECTED ALONG THE
WESTERN PERIPHERY OF THE AZORES-BERMUDA HIGH. PROBABILITIES FOR ABOVE-NORMAL
TEMPERATURES ARE ENHANCED ACROSS SOUTHEAST ALASKA, IN PROXIMITY TO THE
ANOMALOUS RIDGE FORECAST ACROSS THAT AREA. ELEVATED PROBABILITIES FOR
BELOW-NORMAL TEMPERATURES ARE FORECAST FOR THE VICINITY OF THE SOUTHERN ROCKIES
AND SOUTHERN PLAINS, ASSOCIATED WITH THE HEAVY PRECIPITATION EXPECTED BEFORE
AND DURING THE 6-10 DAY PERIOD. THE AREA OF ELEVATED ODDS FOR BELOW-NORMAL
TEMPERATURES CONTINUES EASTWARD AND NORTHEASTWARD ACROSS THE MISSISSIPPI
VALLEY, THE TENNESSEE AND OHIO VALLEYS, THE GREAT LAKES REGION, AND INTERIOR
PORTIONS OF THE MID-ATLANTIC STATES AND NORTHEAST, DUE TO THE INFLUENCES OF A
MID-LEVEL TROUGH AND ASSOCIATED COLD FRONT PASSAGE. CHANCES FOR BELOW-NORMAL
TEMPERATURES ARE INCREASED OVER WESTERN AND CENTRAL ALASKA, ASSOCIATED WITH A
MID-LEVEL TROUGH.
RIDGING FAVORS INCREASED PROBABILITIES OF BELOW-NORMAL PRECIPITATION ACROSS
PARTS OF THE NORTHWEST CONUS AND EXTENDING THROUGH THE NORTH-CENTRAL CONUS,
MIDWEST, AND INDIANA. AN ANOMALOUS CYCLONIC MID-LEVEL CIRCULATION IS FORECAST
TO DEVELOP UNDERNEATH THE RIDGE AXIS, ACROSS NORTHERN BAJA AND FAR SOUTHERN
CALIFORNIA, WHICH FAVORS INCREASING CHANCES FOR PRECIPITATION OVER THE
CLIMATOLOGICALLY DRY AREAS OF THE SOUTHWESTERN CONUS, ESPECIALLY THE HIGHER
TERRAIN. THIS IN TURN FAVORS HIGH PROBABILITIES OF ABOVE-NORMAL PRECIPITATION
OVER THESE AREAS (GREATER THAN 70 PERCENT OVER PARTS OF THE FOUR CORNERS
REGION). CONTINUING EASTWARD, THOUGH NOW WITH THE INCREASING INFLUENCE OF THE
EASTERN CONUS TROUGH AND LOW-LEVEL GULF MOISTURE, PROBABILITIES FOR
ABOVE-NORMAL PRECIPITATION REMAIN ELEVATED ACROSS THE CENTRAL AND SOUTHERN
PLAINS, THE LOWER MISSISSIPPI VALLEY, ALABAMA, EASTERN TENNESSEE, AND FOR ALL
AREAS EAST AND SOUTHEAST OF THE APPALACHIANS INCLUDING FLORIDA. A TROUGH
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
GOOD MODEL AGREEMENT REGARDING AN AMPLIFIED 500-HPA CIRCULATION PATTERN ACROSS
NORTH AMERICA, OFFSET BY DIFFERENCES AMONG THE SURFACE TEMPERATURE AND
PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR MAY 20 - 26 2023
THE 500-HPA HEIGHT PATTERN DURING WEEK-2 IS GENERALLY SIMILAR TO THAT OF THE
6-10 DAY PERIOD, WITH DE-AMPLIFICATION OF THE MID-LEVEL FEATURES. THE LARGEST
MID-LEVEL HEIGHT RISES ASSOCIATED WITH THE WESTERN NORTH AMERICAN RIDGE DURING
WEEK-2 ARE PREDICTED TO BE OFFSHORE OVER THE EASTERN GULF OF ALASKA. THIS
SUGGESTS RETROGRESSION OF THE RIDGE THAT HAS BEEN FORECAST OVER THE WESTERN
PORTION OF NORTH AMERICA FOR AT LEAST THE PAST WEEK. MID-LEVEL TROUGHS ARE
ANTICIPATED OVER EASTERN NORTH AMERICA AND WESTERN ALASKA, AND A WEAK TROUGH IS
INDICATED NEAR THE COAST OF FAR SOUTHERN CALIFORNIA.
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 70 PERCENT OVER THE
NORTHERN INTERMOUNTAIN REGION. ABOVE-NORMAL TEMPERATURES ARE FAVORED OVER THE
FLORIDA PENINSULA AND MUCH OF NEW ENGLAND, EAST OF THE ANTICIPATED TROUGH AXIS
ACROSS THE EAST-CENTRAL CONUS. CONVERSELY, PROBABILITIES FOR BELOW-NORMAL
TEMPERATURES ARE ELEVATED ACROSS THE SOUTHERN ROCKIES AND SOUTHERN PLAINS DUE
TO THE EXPECTATION OF HEAVY PRECIPITATION BEFORE AND DURING PORTIONS OF THE
WEEK-2 PERIOD. THE AREA OF ELEVATED ODDS FOR BELOW-NORMAL TEMPERATURES
CONTINUES EASTWARD AND NORTHEASTWARD ACROSS THE LOWER AND MIDDLE MISSISSIPPI
VALLEY, ALABAMA, GEORGIA, THE SOUTHERN APPALACHIANS, THE TENNESSEE AND LOWER
OHIO VALLEYS, AND MICHIGAN, DUE TO THE INFLUENCE OF THE EASTERN CONUS MID-LEVEL
TROUGH. THIS IS WELL SUPPORTED BY THE GFS AND ECMWF ENSEMBLE MEAN CALIBRATED
REFORECAST TEMPERATURES. CHANCES FOR BELOW-NORMAL TEMPERATURES ARE INCREASED
OVER MOST OF ALASKA SOUTH OF THE BROOKS RANGE, ASSOCIATED WITH A MID-LEVEL
TROUGH.
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, MUCH OF THE SOUTHERN
PLAINS REGION, PORTIONS OF THE LOWER MISSISSIPPI VALLEY, ALABAMA, AND THE
ATLANTIC COAST STATES FROM FLORIDA TO DELAWARE. THIS IS BASED ON INCREASED
MOISTURE ADVECTION ASSOCIATED WITH THE SOUTHWESTERN AND EASTERN CONUS MID-LEVEL
TROUGHS ALREADY DISCUSSED IN THE 6-10 DAY PERIOD. PROBABILITIES OF ABOVE-NORMAL
PRECIPITATION EXCEED 60 PERCENT OVER THE HIGHER TERRAIN OF NORTHERN ARIZONA AND
ADJACENT SOUTHERN UTAH. 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 MONTANA, THE NORTHERN
PLAINS, EASTERN NEBRASKA, THE UPPER AND MIDDLE MISSISSIPPI VALLEY, MUCH OF
MICHIGAN, INDIANA, AND THE LOWER OHIO VALLEY. ELEVATED NEAR- TO ABOVE-NORMAL
PRECIPITATION PROBABILITIES REMAIN FORECAST ACROSS ALASKA, DUE TO THE PROXIMITY
OF A MID-LEVEL TROUGH AND INCREASED ONSHORE FLOW.
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
AN EXPECTED DEAMPLIFICATION OF THE OVERALL 500-HPA HEIGHT PATTERN, A POTENTIAL
WESTWARD SHIFT IN THE MEAN RIDGE OVER WESTERN NORTH AMERICA, 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:
19750509 - 19570501 - 19870503 - 19860525 - 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:
19570430 - 19750509 - 19870503 - 19860524 - 19760425
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 18 - 22 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 B NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A N
UTAH A A ARIZONA A A COLORADO N A
NEW MEXICO B A N DAKOTA N B S DAKOTA N B
NEBRASKA N B KANSAS B A OKLAHOMA B A
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA B B IOWA B B MISSOURI B B
ARKANSAS B A LOUISIANA B A WISCONSIN B B
ILLINOIS B B MISSISSIPPI B A MICHIGAN B N
INDIANA B B OHIO B N KENTUCKY B N
TENNESSEE B N ALABAMA N A NEW YORK B A
VERMONT B A NEW HAMP N A MAINE N A
MASS N A CONN N A RHODE IS N A
PENN B A NEW JERSEY N A W VIRGINIA B N
MARYLAND N A DELAWARE N A VIRGINIA N A
N CAROLINA N A S CAROLINA N A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B A 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 20 - 26 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 N N OKLAHOMA B N
N TEXAS B N S TEXAS B A W TEXAS B A
MINNESOTA N N IOWA N N MISSOURI B N
ARKANSAS B N LOUISIANA B N WISCONSIN N N
ILLINOIS N N MISSISSIPPI B N MICHIGAN B N
INDIANA B N OHIO N N KENTUCKY B N
TENNESSEE B N ALABAMA B 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 A VIRGINIA N A
N CAROLINA N A S CAROLINA N A GEORGIA B A
FL PNHDL N 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 B 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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