074
FXUS06 KWBC 271902
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 27 2023
6-10 DAY OUTLOOK FOR MAY 03 - 07 2023
THE SYNOPTIC PATTERN AS DEPICTED BY THE ENSEMBLE MEANS FROM THE GFS, ECMWF, AND
CANADIAN MODELS SHOW THE 500-HPA HEIGHTS AND ANOMALIES FOR THE 6-10 DAY PERIOD
WITH A PERSISTENT AMPLIFIED PATTERN OVER NORTH AMERICA. THERE IS LIKELY TO BE
TROUGHING OVER THE WEST COAST AND THE NORTHEAST U.S. AND RIDGING OVER THE
ROCKIES AND THE NORTH PACIFIC. AS THE FORECAST PERIOD PROGRESSES THE RIDGE AXIS
OVER CENTRAL NORTH AMERICA BECOMES MORE MERIDIONALLY ORIENTED AND THE SYNOPTIC
PATTERN SETTLES INTO AN OMEGA BLOCK PATTERN. MODEL SOLUTIONS HAVE BEEN
CONVERGING OVER THE LAST FEW DAYS, RESULTING IN HIGHER FORECAST CONFIDENCE.
WITH DEEP TROUGHING OVER THE NORTHEAST U.S., BELOW-NORMAL TEMPERATURES ARE
FAVORED FOR MUCH OF THE EASTERN CONTIGUOUS U.S. (CONUS), PARTICULARLY PORTIONS
OF THE UPPER OHIO VALLEY WHERE PROBABILITIES EXCEED 70%. TROUGHING OFF THE WEST
COAST FAVORS BELOW-NORMAL TEMPERATURES FOR MUCH OF CALIFORNIA AND PORTIONS OF
ADJACENT STATES AS WELL. ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE
ROCKIES AND GREAT BASIN UNDER ANOMALOUS RIDGING. TROUGHING OVER THE BERING SEA
RESULTS IN MOIST SOUTHWESTERLY FLOW FOR ALASKA LEADING TO THE POTENTIAL FOR
INCREASED CLOUDINESS, FAVORING BELOW-NORMAL TEMPERATURES FOR SOUTHWESTERN
MAINLAND ALASKA, WHILE NEAR-NORMAL TEMPERATURES ARE MOST LIKELY FOR THE NORTH
SLOPE AND SOUTHEAST ALASKA.
RIDGING OVER THE ROCKIES RESULTS IN A TILT TOWARDS BELOW-NORMAL PRECIPITATION
FOR A BROAD SWATH OF THE CENTRAL AND EASTERN CONUS, WITH THE HIGHEST
PROBABILITIES (>50%) OVER THE UPPER MIDWEST AND ENHANCED PROBABILITIES OF
BELOW-NORMAL PRECIPITATION EXTENDING SOUTHEASTWARD OVER THE MIDDLE MISSISSIPPI
VALLEY, THE OHIO AND TENNESSEE VALLEYS, AND THE MID-ATLANTIC. ABOVE-NORMAL
PRECIPITATION IS FAVORED FOR MUCH OF THE WESTERN CONUS AND PORTIONS OF THE
SOUTHERN PLAINS WITH A MID-LEVEL TROUGH IN PLACE OVER THE WEST COAST THROUGHOUT
THE FORECAST PERIOD, WITH PROBABILITIES EXCEEDING 60% FOR MUCH OF CALIFORNIA.
ONSHORE FLOW OFF THE NORTH PACIFIC RESULTS IN A TILT TOWARDS ABOVE-NORMAL
PRECIPITATION FOR MUCH OF MAINLAND ALASKA, WHILE NEAR-NORMAL PRECIPITATION IS
MOST LIKELY FOR SOUTHEAST 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: VERY HIGH, 5 OUT OF 5, WITH STRONG
AGREEMENT AMONG ENSEMBLE MODELS ON A PERSISTENT OMEGA-TYPE SYNOPTIC PATTERN.
8-14 DAY OUTLOOK FOR MAY 05 - 11 2023
THE SYNOPTIC PATTERN FOR THE 8-14 DAY PERIOD AS DEPICTED IN MODEL ENSEMBLE
SOLUTIONS MAINTAIN 500-HPA HEIGHT ANOMALIES VERY SIMILAR TO WHAT IS SHOWN FOR
THE 6-10 PERIOD, WITH CONTINUED TROUGHING OVER THE WEST COAST AND RIDGING OVER
THE ROCKIES. THE TROUGH DEPICTED OVER THE NORTHEAST U.S. IN THE EARLIER PERIOD
IS SLIGHTLY SHIFTED EASTWARD OVER THE NORTH ATLANTIC AND HEIGHT ANOMALIES
OVERALL HAVE A LOWER MAGNITUDE AS THE HIGH AMPLITUDE PATTERN EASES SOMEWHAT BUT
THE OVERALL OMEGA PATTERN REMAINS IN PLACE. THIS RESULTS IN TEMPERATURE AND
PRECIPITATION FORECASTS FOR THE 8-14 DAY PERIOD THAT ARE VERY SIMILAR TO THE
6-10 DAY PERIOD, ALTHOUGH WITH SLIGHTLY LOWER PROBABILITIES GIVEN A LESS
AMPLIFIED FLOW PATTERN.
AS THE EASTERN TROUGH SHIFTS FROM THE GREAT LAKES TO OVER THE NORTH ATLANTIC,
TEMPERATURES WILL MODERATE BUT BELOW-NORMAL TEMPERATURES REMAIN FAVORED FOR
MUCH OF THE EASTERN CONUS, WITH PROBABILITIES EXCEEDING 50% FOR PORTIONS OF THE
APPALACHIANS AND OHIO VALLEY. BELOW-NORMAL TEMPERATURES CONTINUE TO BE MOST
LIKELY FOR CALIFORNIA, MUCH OF NEVADA AND ARIZONA, AND ADJACENT AREAS AS
TROUGHING CONTINUES OVER THE WEST COAST. THE PERSISTENT ANOMALOUS RIDGE OVER
THE ROCKIES RESULTS IN A TILT TOWARDS ABOVE-NORMAL TEMPERATURES FOR THE
NORTHERN AND CENTRAL ROCKIES AS WELL AS MUCH OF THE GREAT PLAINS. ONGOING
SOUTHWESTERLY FLOW OFF THE BERING SEA FAVORS CONTINUED CLOUDINESS AND
PRECIPITATION RESULTING IN BELOW-NORMAL TEMPERATURES FOR SOUTHWESTERN MAINLAND
ALASKA.
THE PERSISTENT MID-LEVEL TROUGH OVER THE WEST COAST FAVORS ABOVE-NORMAL
PRECIPITATION FOR MUCH OF THE WESTERN CONUS, ESPECIALLY FOR CENTRAL CALIFORNIA,
WHERE PROBABILITIES EXCEED 60%. BUILDING HIGH PRESSURE OVER THE GREAT PLAINS
AND TROUGHING OVER THE NORTH ATLANTIC SETS UP MOIST SOUTHEASTERLY FLOW OFF THE
GULF OF MEXICO AND A TILT TOWARDS ABOVE-NORMAL PRECIPITATION FOR PORTIONS OF
THE SOUTHERN AND CENTRAL PLAINS. THE STRENGTHENING RIDGE OVER THE GREAT PLAINS
RESULTS IN INCREASING PROBABILITIES FOR BELOW-NORMAL PRECIPITATION OVER
PORTIONS OF THE NORTHERN PLAINS, THE OHIO, TENNESSEE, AND UPPER AND MIDDLE
MISSISSIPPI VALLEYS, THE MID-ATLANTIC, THE NORTHEAST AND SOUTHEAST U.S.
CONTINUED SOUTHWESTERLY FLOW ALOFT OVER MAINLAND ALASKA FAVORS A CONTINUED TILT
TOWARDS ABOVE-NORMAL PRECIPITATION FOR MUCH OF THE STATE, EXCEPT FOR SOUTHEAST
ALASKA, WHERE BELOW-NORMAL PRECIPITATION IS FAVORED.
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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG MODEL ENSEMBLES ON THE PERSISTENT SYNOPTIC PATTERN, OFFSET
BY WEAKER ANOMALIES REDUCING FORECAST CONFIDENCE.
FORECASTER: DANIEL BARANDIARAN
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:
19730426 - 20080503 - 19510411 - 19540505 - 20060510
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:
19540504 - 20080503 - 19730427 - 19510411 - 19990413
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 03 - 07 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF B A
SRN CALIF B A IDAHO A A NEVADA B A
W MONTANA A N E MONTANA A B WYOMING A N
UTAH A A ARIZONA B A COLORADO A A
NEW MEXICO A A N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS N A W TEXAS A A
MINNESOTA N B IOWA N B MISSOURI B B
ARKANSAS B B LOUISIANA B N WISCONSIN B B
ILLINOIS B B MISSISSIPPI B N MICHIGAN B B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE B B ALABAMA B N NEW YORK B N
VERMONT B N NEW HAMP B N MAINE B N
MASS B N CONN B N RHODE IS B N
PENN B N NEW JERSEY B N W VIRGINIA B B
MARYLAND B B DELAWARE B N VIRGINIA B B
N CAROLINA B B S CAROLINA B B GEORGIA B N
FL PNHDL B N FL PENIN B N AK N SLOPE N A
AK ALEUTIAN N A AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST B A AK PNHDL B N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 05 - 11 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON B A NRN CALIF B A
SRN CALIF B A IDAHO A A NEVADA B A
W MONTANA A A E MONTANA A N WYOMING A A
UTAH A A ARIZONA B N COLORADO A A
NEW MEXICO N A N DAKOTA A B S DAKOTA A B
NEBRASKA A N KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS N A W TEXAS A N
MINNESOTA A B IOWA N B MISSOURI N B
ARKANSAS B B LOUISIANA B N WISCONSIN N B
ILLINOIS B B MISSISSIPPI B N MICHIGAN B B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE B B ALABAMA B N NEW YORK B B
VERMONT B N NEW HAMP B N MAINE B N
MASS B N CONN B N RHODE IS B N
PENN B B NEW JERSEY B B W VIRGINIA B B
MARYLAND B B DELAWARE B B VIRGINIA B B
N CAROLINA B B S CAROLINA B B GEORGIA B N
FL PNHDL B N FL PENIN N N 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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