469
FXUS06 KWBC 201902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU APRIL 20 2023
6-10 DAY OUTLOOK FOR APR 26 - 30 2023
MODEL SOLUTIONS ARE IN EXCELLENT AGREEMENT AND REMAIN CONSISTENT THAT A
WEST-BASED NEGATIVE NORTH ATLANTIC OSCILLATION (NAO) BECOMES PREVALENT DURING
LATE APRIL. THIS -NAO ALONG WITH ANOMALOUS RIDGING UPSTREAM SUPPORTS INCREASED
PROBABILITIES FOR BELOW-NORMAL TEMPERATURES ACROSS THE EASTERN TWO-THIRDS OF
THE CONUS. THE ONE EXCEPTION TO THIS COOLER-THAN-NORMAL TEMPERATURE PATTERN
OVER THE EAST IS ACROSS THE FLORIDA PENINSULA WHICH IS FORECAST TO BE REMOVED
FROM THE STRONGER COLD AIR ADVECTION AT THE THE BEGINNING OF THE 6-10 DAY
PERIOD. FARTHER TO THE WEST, ANOMALOUS RIDGING FAVORS ABOVE-NORMAL TEMPERATURES
FOR THE WESTERN THIRD OF THE CONUS.
THE MADDEN-JULIAN OSCILLATION (MJO) IS CURRENTLY CENTERED ACROSS THE EAST
PACIFIC AND IS FORECAST TO CONTINUE PROPAGATING EASTWARD FROM THE AMERICAS TO
AFRICA. THIS MJO EVOLUTION TYPICALLY ENHANCES SUBTROPICAL MOISTURE ACROSS THE
SOUTHERN TIER OF THE CONUS. FROM DAYS 6 TO 8 (APRIL 26-28), THE ENSEMBLE MEANS
AND THEIR DETERMINISTIC MODEL RUNS FEATURE A SHORTWAVE TROUGH AND ASSOCIATED
LOW PRESSURE SYSTEM TRACKING FROM THE SOUTHERN GREAT PLAINS TO THE EAST COAST.
ALONG ITS PREDICTED TRACK, ABOVE-NORMAL PRECIPITATION IS FAVORED WITH THE
LARGEST PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION LOCATED ACROSS THE
SOUTHEAST, CONSISTENT WITH MJO COMPOSITES AND THE DYNAMICAL MODELS. THE
AMPLIFIED RIDGE SUPPORTS INCREASED BELOW-NORMAL PRECIPITATION PROBABILITIES FOR
THE PACIFIC NORTHWEST, NORTHERN AND CENTRAL CALIFORNIA, NORTHERN ROCKIES, AND
GREAT BASIN. THE LARGEST UNCERTAINTY IN THE 6-10 DAY PRECIPITATION OUTLOOK
EXISTS ACROSS THE GREAT PLAINS DUE TO TIMING DIFFERENCES ON HOW FAST A
SHORTWAVE TROUGH TRACKS EASTWARD. THE SLOWER ECMWF AND CANADIAN MODEL SOLUTIONS
ARE PREFERRED DUE TO THE BLOCKING REGIME DOWNSTREAM, WHICH LEADS TO SLIGHTLY
ELEVATED PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION FROM THE CENTRAL TO
SOUTHERN GREAT PLAINS WEST TO THE ROCKIES.
A HIGH AMPLITUDE TROUGH WITH NEGATIVE 500-HPA HEIGHT ANOMALIES FAVORS
BELOW-NORMAL TEMPERATURES ACROSS MUCH OF MAINLAND ALASKA. HOWEVER, MEAN
SOUTHERLY FLOW ASSOCIATED WITH A SURFACE LOW CENTERED OVER THE ALEUTIANS FAVORS
NEAR-NORMAL TEMPERATURES FOR SOUTHEASTERN ALASKA. THE PATTERN ALOFT AND AT THE
SURFACE SUPPORT INCREASED CHANCES FOR ABOVE-NORMAL PRECIPITATION THROUGHOUT A
MAJORITY OF ALASKA.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 35% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 35% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
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
EXCELLENT AGREEMENT AMONG THE ENSEMBLE MEANS OFFSET SLIGHTLY BY UNCERTAINTY IN
THE PRECIPITATION OUTLOOK FOR THE GREAT PLAINS.
8-14 DAY OUTLOOK FOR APR 28 - MAY 04, 2023
THE CANADIAN, GFS, AND ECMWF ENSEMBLE MEANS MAINTAIN A STABLE LONGWAVE PATTERN
OVER EASTERN NORTH AMERICA INTO THE BEGINNING OF MAY WITH A BLOCKING RIDGE
CENTERED OVER THE DAVIS STRAIT AND A HIGHLY AMPLIFIED TROUGH ACROSS THE EAST.
THEREFORE, A LARGE COVERAGE OF BELOW-NORMAL TEMPERATURES ARE FAVORED FOR A
MAJORITY OF THE EASTERN TWO-THIRDS OF THE CONUS. GIVEN THE LIKELIHOOD OF A
PERSISTENT -NAO, COOLER TEMPERATURES ARE EXPECTED TO EXPAND SOUTHWARD ACROSS
THE FLORIDA PENINSULA BY THE END OF APRIL. AN AMPLIFIED RIDGE FAVORS
ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE WESTERN CONUS. HOWEVER, THE ENSEMBLE
MEANS DEPICT A TROUGH UNDERCUTTING THIS RIDGE AND APPROACHING THE WEST COAST
LATER IN WEEK-2. A COOLING TREND IS EXPECTED ACROSS CALIFORNIA WITH NEAR TO
BELOW-NORMAL TEMPERATURES FAVORED FOR PARTS OF CALIFORNIA AND THE DESERT
SOUTHWEST.
AN AMPLIFYING LONGWAVE TROUGH SUPPORTS INCREASED ABOVE-NORMAL PRECIPITATION
PROBABILITIES FROM THE APPALACHIANS TO THE EAST COAST ALONG WITH THE GULF
COAST. THIS FAVORED AREA OF ABOVE-NORMAL PRECIPITATION EXTENDS WEST TO THE RIO
GRANDE VALLEY AND SOUTHERN HIGH PLAINS, DUE TO A PREDICTED STATIONARY FRONT.
ABOVE-NORMAL PRECIPITATION IS ALSO FAVORED ACROSS CALIFORNIA AND THE GREAT
BASIN, DUE TO THE TROUGH APPROACHING THE WEST COAST. ALONG AND TO THE EAST OF A
500-HPA RIDGE AXIS, ELEVATED PROBABILITIES FOR BELOW-NORMAL PRECIPITATION ARE
FORECAST ACROSS THE NORTHERN TIER OF THE CONUS AS WELL AS THE MIDWEST.
THE 500-HPA TROUGH AXIS, INITIALLY OVER WESTERN MAINLAND ALASKA, IS FORECAST TO
RETROGRADE WESTWARD TO THE BERING SEA. THIS PATTERN CHANGE RESULTS IN A DRYING
AND WARMING TREND ACROSS SOUTHEASTERN ALASKA FROM THE 6-10 DAY PERIOD.
OTHERWISE, THE NEARBY AMPLIFIED TROUGH CONTINUES TO FAVOR BELOW-NORMAL
TEMPERATURES AND ABOVE-NORMAL PRECIPITATION FOR THE REMAINDER OF ALASKA.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 35% OF TODAY'S 0Z 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
GOOD MODEL AGREEMENT AND CONTINUITY.
FORECASTER: BRAD PUGH
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:
19790413 - 19520401 - 19780415 - 19660411 - 19530407
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:
19790412 - 19780415 - 19530407 - 19520331 - 19960330
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR APR 26 - 30 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A B
SRN CALIF A N IDAHO A B NEVADA A B
W MONTANA B B E MONTANA B B WYOMING B N
UTAH A B ARIZONA A N COLORADO B A
NEW MEXICO B A N DAKOTA B N S DAKOTA B N
NEBRASKA B A KANSAS B A OKLAHOMA B A
N TEXAS B A S TEXAS B N W TEXAS B N
MINNESOTA B N IOWA B N MISSOURI B A
ARKANSAS B A LOUISIANA B A WISCONSIN B N
ILLINOIS B A MISSISSIPPI B A MICHIGAN B N
INDIANA B A OHIO B A KENTUCKY B A
TENNESSEE B A ALABAMA B A NEW YORK B A
VERMONT N A NEW HAMP N A MAINE N N
MASS B A CONN B A RHODE IS B A
PENN B A NEW JERSEY B A W VIRGINIA B A
MARYLAND B A DELAWARE B A VIRGINIA B A
N CAROLINA B A S CAROLINA B A GEORGIA B A
FL PNHDL B A FL PENIN A A AK N SLOPE B A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST B A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR APR 28 - MAY 04, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A N NRN CALIF A A
SRN CALIF B A IDAHO A N NEVADA A A
W MONTANA A B E MONTANA B B WYOMING B N
UTAH A N ARIZONA N N COLORADO B N
NEW MEXICO N N N DAKOTA B B S DAKOTA B B
NEBRASKA B B KANSAS B N OKLAHOMA B N
N TEXAS B N S TEXAS B A W TEXAS B N
MINNESOTA B B IOWA B B MISSOURI B B
ARKANSAS B B LOUISIANA B N WISCONSIN B B
ILLINOIS B B MISSISSIPPI B N MICHIGAN B N
INDIANA B B OHIO B N KENTUCKY B N
TENNESSEE B N ALABAMA B A NEW YORK B A
VERMONT B A NEW HAMP B A MAINE N A
MASS B A CONN B A RHODE IS B A
PENN B A NEW JERSEY B A W VIRGINIA B A
MARYLAND B A DELAWARE B A VIRGINIA B A
N CAROLINA B A S CAROLINA B A GEORGIA B A
FL PNHDL B A FL PENIN N A AK N SLOPE B A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN N A
AK S INT N A AK SO COAST B A 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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