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FXUS06 KWBC 041902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI AUGUST 04 2023
6-10 DAY OUTLOOK FOR AUG 10 - 14 2023
THE GFS, ECMWF, AND CANADIAN ENSEMBLE MEANS ALONG WITH THEIR DETERMINISTIC 0Z
GFS AND 0Z ECMWF MODELS ARE IN EXCELLENT AGREEMENT ON THE PREDICTED LONGWAVE
PATTERN DURING THE 6-10 DAY PERIOD. THE MANUAL 500-HPA HEIGHT BLEND FEATURES A
DEEP, ANOMALOUS TROUGH CENTERED OVER THE ALEUTIANS ALONG WITH AN AMPLIFIED
RIDGE (TROUGH) OVER WESTERN (EASTERN) NORTH AMERICA. THE AMPLIFIED TROUGH
FAVORS BELOW NORMAL TEMPERATURES FOR THE ALEUTIANS, ALASKA PENINSULA, AND
SOUTHWESTERN MAINLAND ALASKA, WHILE SOUTHERLY SURFACE FLOW SUPPORTS INCREASED
ABOVE NORMAL TEMPERATURE PROBABILITIES FOR THE REMAINDER OF ALASKA. ANOMALOUS
RIDGING SUPPORTS INCREASED ABOVE NORMAL TEMPERATURE PROBABILITIES THROUGHOUT
THE WESTERN AND SOUTHERN CONUS. THE EAST COAST IS ALSO FAVORED TO BE ABOVE
NORMAL AS THIS REGION IS INFLUENCED BY SOUTHERLY SURFACE FLOW AND IS WELL
DISPLACED FROM 500-HPA HEIGHT FALLS. PROBABILITIES FOR ABOVE NORMAL
TEMPERATURES EXCEED 80 PERCENT ACROSS PARTS OF TEXAS, DUE TO GOOD MODEL SUPPORT
AND CONTINUITY.
THE AMPLIFIED TROUGH OVER EASTERN NORTH AMERICA LEADS TO INCREASED ABOVE NORMAL
PRECIPITATION PROBABILITIES ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS
FAVORED WETNESS EXTENDS AS FAR SOUTH AS NORTHERN TEXAS, THE LOWER MISSISSIPPI
VALLEY, AND THE SOUTHEAST BASED ON THE GEFS AND ECMWF REFORECAST TOOLS. ALSO,
THE ANALOG TOOL DERIVED FROM THE 500-HPA HEIGHT BLEND SUPPORTS THE WET AREA
ACROSS THE SOUTHERN GREAT PLAINS AND IS CONSISTENT WITH AN AMPLIFIED TROUGH
OVER THE CENTRAL CONUS. MODEL SOLUTIONS DEPICT A 500-HPA RIDGE AXIS OVER
NORTHERN MEXICO AND THE RIO GRANDE VALLEY WHICH IS LIKELY TO SUPPRESS THE
MONSOON, WHICH FAVORS BELOW NORMAL PRECIPITATION ACROSS THE SOUTHWEST. THE
DRIER ECMWF BASED TOOLS WERE PREFERRED FOR THE PACIFIC NORTHWEST AND
INTERMOUNTAIN WEST (GIVEN THE STRENGTHENING RIDGE ALOFT) WHERE THE FAVORED
WETNESS FROM YESTERDAY WAS CHANGED TO EITHER NEAR NORMAL OR SLIGHTLY ELEVATED
BELOW NORMAL PRECIPITATION PROBABILITIES.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 10% OF TODAY'S OPERATIONAL 0Z GFS CENTERED ON
DAY 8, 30% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 10% OF
TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8, AND 20% 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 ON AN AMPLIFIED LONGWAVE PATTERN.
8-14 DAY OUTLOOK FOR AUG 12 - 18 2023
ENSEMBLE MEANS ARE IN GOOD AGREEMENT THAT THE LONGWAVE PATTERN OVER THE NORTH
PACIFIC AND NORTH AMERICA BECOMES STABLE DURING MID-AUGUST WITH A PERSISTENT,
ANOMALOUS TROUGH OVER THE BERING SEA AND ALEUTIANS AND A HIGHLY AMPLIFIED RIDGE
ACROSS THE WESTERN CONUS. THIS HIGH AMPLITUDE RIDGE AND ASSOCIATED POSITIVE
500-HPA HEIGHT ANOMALIES SUPPORT INCREASED ABOVE NORMAL TEMPERATURE
PROBABILITIES THROUGHOUT THE WESTERN AND SOUTHERN CONUS. THE MANUAL 500-HPA
BLEND DEPICTS 7-DAY HEIGHT DEPARTURES OF MORE THAN 90 METERS ACROSS THE PACIFIC
NORTHWEST. BASED ON GOOD MODEL CONTINUITY AND AGREEMENT BETWEEN THE DYNAMICAL
MODEL OUTPUT AND ANALOG TOOL, PROBABILITIES FOR ABOVE NORMAL TEMPERATURES
EXCEED 80 PERCENT ACROSS PARTS OF WASHINGTON AND OREGON. THE 500-HPA TROUGH
OVER THE CENTRAL CONUS IS EXPECTED TO CONTINUE DOWNSTREAM OF THE AMPLIFIED
RIDGE NEAR THE WEST COAST. THIS TROUGH AND PERIODIC NORTHERLY SURFACE FLOW
FAVOR BELOW NORMAL TEMPERATURES ACROSS THE NORTHERN TO CENTRAL GREAT PLAINS AND
MIDDLE TO UPPER MISSISSIPPI VALLEY. TO THE EAST OF THE LONGWAVE TROUGH AXIS AND
DUE TO 7-DAY MEAN SOUTHERLY FLOW, ABOVE NORMAL TEMPERATURES ARE MOST LIKELY
FROM THE APPALACHIANS TO THE EAST COAST. GIVEN THE PERSISTENT LONGWAVE PATTERN
THE ALASKA TEMPERATURE OUTLOOK IS VERY SIMILAR TO THE 6-10 DAY PERIOD.
THE 500-HPA TROUGH, CENTERED OVER THE MISSISSIPPI VALLEY, CONTINUES TO FAVOR
ABOVE NORMAL PRECIPITATION THROUGHOUT A MAJORITY OF THE CENTRAL AND EASTERN
CONUS. BASED ON THE GEFS AND ECMWF REFORECAST TOOLS, THE UNCALIBRATED GEFS, AND
THE ANALOG TOOL DERIVED FROM THE MANUAL 500-HPA HEIGHT BLEND, THE WEEK-2
OUTLOOK LEANS WET FOR FLORIDA ALONG WITH MUCH OF THE GULF COAST AND TEXAS.
THERE ALSO CONTINUES TO BE AN INCREASED POTENTIAL FOR EASTERLY WAVES TO TRACK
FROM THE CARIBBEAN NORTHWESTWARD TO THE GULF OF MEXICO. THE 500-HPA RIDGE AXIS
IS FORECAST TO SLIGHTLY SHIFT NORTHWARD LATER IN WEEK-2 WHICH MAY EVENTUALLY
LEAD TO ENHANCED MONSOON FLOW INTO THE SOUTHWEST. THEREFORE, PROBABILITIES FOR
BELOW NORMAL PRECIPITATION ACROSS THIS REGION ARE REDUCED COMPARED TO
YESTERDAY. THE STRONG RIDGE ALOFT SUPPORTS INCREASED BELOW NORMAL PRECIPITATION
PROBABILITIES FOR THE PACIFIC NORTHWEST AND INTERMOUNTAIN WEST. THE
STRENGTHENING RIDGE OVER WESTERN NORTH AMERICA LED TO A SLIGHT LEAN TOWARDS
DRYNESS FOR PARTS OF SOUTHEASTERN ALASKA, BUT THE ENHANCED ONSHORE FLOW
CONTINUES TO FAVOR 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: AVERAGE, 4 OUT OF 5, DUE TO GOOD
MODEL AGREEMENT AND CONTINUITY ON A HIGHLY AMPLIFIED LONGWAVE PATTERN FOR
MID-AUGUST.
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
AUGUST 17.
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:
19540808 - 19630813 - 19970727 - 19560715 - 19980731
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:
19540808 - 20040806 - 19980731 - 19970726 - 19960720
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 10 - 14 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A N NRN CALIF A N
SRN CALIF A N IDAHO N B NEVADA A B
W MONTANA B N E MONTANA B A WYOMING B A
UTAH A B ARIZONA A B COLORADO A A
NEW MEXICO A B N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS N A OKLAHOMA A A
N TEXAS A N S TEXAS A N W TEXAS A B
MINNESOTA B A IOWA B A MISSOURI B A
ARKANSAS A A LOUISIANA A N WISCONSIN B A
ILLINOIS B A MISSISSIPPI A A MICHIGAN B A
INDIANA N A OHIO N A KENTUCKY N A
TENNESSEE A A ALABAMA A A NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A A NEW JERSEY A A W VIRGINIA A A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A A GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE A A
AK ALEUTIAN B A AK WESTERN A A AK INT BSN A A
AK S INT A A AK SO COAST B A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 12 - 18 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 N E MONTANA B A WYOMING B A
UTAH A N ARIZONA A N COLORADO B A
NEW MEXICO A N N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS B A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA B A IOWA B A MISSOURI B A
ARKANSAS A A LOUISIANA A A WISCONSIN B A
ILLINOIS B A MISSISSIPPI A A MICHIGAN B A
INDIANA N A OHIO N A KENTUCKY N A
TENNESSEE A A ALABAMA A A NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A A NEW JERSEY A A W VIRGINIA A A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B A AK WESTERN A A AK INT BSN A A
AK S INT B A AK SO COAST B A AK PNHDL A B
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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