626
FXUS06 KWBC 181902
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 18 2023
6-10 DAY OUTLOOK FOR AUG 24 - 28 2023
MID-LEVEL TROUGHING IS FORECASTED ACROSS MUCH OF THE WEST COAST AND NORTHEAST
BENEATH NEGATIVE 500-HPA HEIGHT ANOMALIES. ACROSS THE CENTRAL CONTIGUOUS U.S.
(CONUS) RIDGING LOOKS LIKELY TO PERSIST ALTHOUGH IT MAY WEAKEN BY THE END OF
THE PERIOD. MEANWHILE, STRONGLY POSITIVE 500-HPA HEIGHT ANOMALIES ARE
FORECASTED TO BE CENTERED IN THE GULF OF ALASKA AND STRETCH INTO MUCH OF
ALASKA, EXCLUDING THE ALEUTIAN ISLANDS WHERE NEGATIVE 500-HPA HEIGHT ANOMALIES
ARE FORECAST.
BELOW-NORMAL TEMPERATURES ARE FORECASTED FOR THE NORTHEAST AND PARTS OF THE
MID-ATLANTIC DURING THE PERIOD BENEATH NEGATIVE 500-HPA HEIGHT ANOMALIES. A
SECOND AREA OF BELOW-NORMAL TEMPERATURES IS SLIGHTLY FAVORED IN PARTS OF THE
SOUTHWEST DUE TO GULF OF CALIFORNIA MOISTURE SURGES FROM HURRICANE HILARY AND A
SYSTEM THAT MAY POTENTIALLY DEVELOP BEHIND THIS STORM. HOWEVER, MUCH OF THE
COUNTRY REMAINS FAVORED TO SEE ABOVE-NORMAL TEMPERATURES. THE HIGHEST
PROBABILITIES (>80%) REMAIN ALONG PORTIONS OF THE GULF COAST AND SOUTHEAST
WHERE RIDGING REMAINS INTACT DURING THE FORECAST PERIOD. A SECOND AREA OF
ABOVE-NORMAL TEMPERATURES IS FAVORED IN PORTIONS OF THE PACIFIC NORTHWEST NEAR
THE STRONG POSITIVE 500-HPA HEIGHT ANOMALIES FOCUSED ACROSS THE GULF OF ALASKA.
AN AREA OF NEAR-NORMAL TEMPERATURES IS FAVORED ACROSS INTERIOR PORTIONS OF THE
WEST AND NORTHERN PLAINS WHERE PRECIPITATION MAY LIMIT MAXIMUM TEMPERATURES. IN
ALASKA, ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR NEARLY ALL OF THE STATE,
EXCLUDING PORTIONS OF THE NORTHWEST MAINLAND WHERE BELOW-NORMAL TEMPERATURES
ARE SLIGHTLY FAVORED, BENEATH STRONG POSITIVE 500-HPA HEIGHT ANOMALIES.
ABOVE-NORMAL PRECIPITATION REMAINS FAVORED IN MUCH OF THE WEST, SIMILAR TO
PREVIOUS FORECASTS. LARGE AMOUNTS OF TROPICAL MOISTURE ARE FORECAST TO BE
TRANSPORTED INTO THE REGION BY HURRICANE HILARY DURING THE WEEK-1 PERIOD. A
SECOND SYSTEM MAY ALSO DEVELOP AND MAY HELP TO REINFORCE SOME OF THE TROPICAL
MOISTURE IN THE REGION. THEREFORE, ABOVE-NORMAL PRECIPITATION IS FAVORED WITH
THE HIGHEST CHANCES IN PARTS OF IDAHO AND EASTERN OREGON. BELOW-NORMAL
PRECIPITATION IS FAVORED FOR PARTS OF THE SOUTHEAST, GULF COAST, AND
MISSISSIPPI VALLEY BENEATH 500-HPA RIDGING. ABOVE-NORMAL PRECIPITATION IS AGAIN
FAVORED IN THE NORTHEAST BENEATH 500-HPA TROUGHING. IN ALASKA, THE SOUTHEAST IS
FAVORED TO HAVE BELOW-NORMAL PRECIPITATION DURING THE PERIOD WHILE MUCH OF THE
MAINLAND IS SLIGHTLY FAVORED TO SEE ABOVE-NORMAL PRECIPITATION AS DEPICTED BY
THE REFORECAST AND RAW GUIDANCE.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 30% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED
ON DAY 8, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN 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, FAIR
AGREEMENT AMONG THE HEIGHT PATTERN AND TEMPERATURE GUIDANCE IS OFFSET BY LOWER
AGREEMENT IN PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR AUG 26 - SEP 01, 2023
THE WEEK-2 MID-LEVEL HEIGHT PATTERN AS DEPICTED BY A BLEND OF THE ECMWF, GEFS,
AND CANADIAN ENSEMBLES IS VERY SIMILAR TO THE 6 TO 10 DAY HEIGHT PATTERN. WEAK
TROUGHING PERSISTS ALONG AND JUST OFF BOTH THE WEST COAST AND EAST COAST.
MEANWHILE, WEAK RIDGING CONTINUES TO PERSIST ACROSS MUCH OF THE CENTRAL CONUS.
STRONGLY POSITIVE HEIGHT ANOMALIES REMAIN IN THE GULF OF ALASKA, ALTHOUGH
FURTHER EAST RELATIVE TO THE 6 TO 10 DAY PERIOD. NEGATIVE HEIGHT ANOMALIES AND
TROUGHING PERSISTS ACROSS THE ALEUTIAN ISLANDS AND WESTERN MAINLAND ALASKA.
THE WEEK-2 TEMPERATURE OUTLOOK IS VERY SIMILAR TO THE 6-10 DAY PERIOD.
ABOVE-NORMAL TEMPERATURES REMAIN FAVORED IN MUCH OF THE CONUS WITH THE
STRONGEST CHANCES ACROSS THE LOWER MISSISSIPPI VALLEY AND SOUTHERN PLAINS, AS
IT HAS BEEN MUCH OF THE SUMMER. CHANCES FOR ABOVE-NORMAL TEMPERATURES IN THE
NORTHERN AND CENTRAL PLAINS ARE SLIGHTLY REDUCED RELATIVE TO YESTERDAY AS THE
RIDGING DAMPENS THROUGHOUT THE PERIOD. ABOVE-NORMAL TEMPERATURES REMAIN FAVORED
IN PARTS OF THE PACIFIC NORTHWEST, THE RESULT OF STRONG POSITIVE 500-HPA HEIGHT
ANOMALIES IN THE GULF OF ALASKA. ELSEWHERE, NEAR- TO BELOW-NORMAL TEMPERATURES
ARE FAVORED FROM PARTS OF SOUTHERN CALIFORNIA NORTH THROUGH THE GREAT BASIN AND
INTO THE NORTHERN PLAINS WHERE LINGERING TROPICAL MOISTURE MAY LIMIT MAXIMUM
TEMPERATURES. IN THE NORTHEAST, BENEATH MID-LEVEL TROUGHING, BELOW-NORMAL
TEMPERATURES ARE FAVORED. IN ALASKA, NEARLY THE ENTIRE STATE IS FAVORED TO HAVE
ABOVE-NORMAL TEMPERATURES DURING THE WEEK-2 PERIOD BENEATH STRONG POSITIVE
500-HPA HEIGHT ANOMALIES.
ABOVE-NORMAL PRECIPITATION REMAINS FAVORED, AS WITH THE 6 TO 10 DAY FORECAST,
ACROSS MUCH OF THE WEST. HOWEVER, MODEL GUIDANCE HAS THE TROPICAL MOISTURE
PROGRESSING FURTHER NORTH BY THE WEEK-2 PERIOD, THEREFORE NEAR-NORMAL
PRECIPITATION IS FAVORED ACROSS PARTS OF THE SOUTHWEST. BELOW-NORMAL
PRECIPITATION REMAINS FAVORED ACROSS MUCH OF THE MISSISSIPPI VALLEY NORTH TO
PORTIONS OF THE CORN BELT. ABOVE-NORMAL PRECIPITATION REMAINS SLIGHTLY FAVORED
IN PORTIONS OF THE NORTHEAST. IN ALASKA, ABOVE-NORMAL PRECIPITATION IS
GENERALLY FAVORED FOR MUCH OF THE MAINLAND, WHILE BELOW-NORMAL PRECIPITATION
CONTINUES TO BE WEAKLY FAVORED IN SOUTHEAST ALASKA AS NORMAL PRECIPITATION FOR
THIS TIME OF YEAR INCREASES, BUT FORECASTED AMOUNTS FAIL TO KEEP UP.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 30% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED
ON DAY 11, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 20%
OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: AVERAGE, 3 OUT 5, ALTHOUGH THE
FLOW PATTERN IS RELATIVELY ZONAL WHICH REDUCES CONFIDENCE, GOOD AGREEMENT AMONG
THE TEMPERATURE AND PRECIPITATION GUIDANCE INCREASES CONFIDENCE.
FORECASTER: RYAN BOLT
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
SEPTEMBER 21.
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:
19910819 - 19970812 - 20020812 - 19870808 - 20020819
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:
20020816 - 19910819 - 19970811 - 19520831 - 19870809
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 24 - 28 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF N A
SRN CALIF B A IDAHO N A NEVADA B A
W MONTANA N A E MONTANA N A WYOMING N A
UTAH N A ARIZONA A A COLORADO A A
NEW MEXICO A A N DAKOTA N A S DAKOTA A A
NEBRASKA A A KANSAS A N OKLAHOMA A N
N TEXAS A B S TEXAS A B W TEXAS A N
MINNESOTA N N IOWA A N MISSOURI A B
ARKANSAS A B LOUISIANA A B WISCONSIN A B
ILLINOIS A B MISSISSIPPI A B MICHIGAN N N
INDIANA A B OHIO A N KENTUCKY A B
TENNESSEE A B ALABAMA A B NEW YORK B A
VERMONT B A NEW HAMP B A MAINE B A
MASS B A CONN B A RHODE IS B A
PENN B A NEW JERSEY B A W VIRGINIA A N
MARYLAND N A DELAWARE N A VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE N A
AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A
AK S INT A A AK SO COAST A A AK PNHDL A B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 26 - SEP 01, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF N A
SRN CALIF B N IDAHO N A NEVADA N A
W MONTANA N A E MONTANA N A WYOMING N A
UTAH A A ARIZONA A N COLORADO A A
NEW MEXICO A N N DAKOTA N A S DAKOTA N A
NEBRASKA A A KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS A N W TEXAS A N
MINNESOTA N A IOWA A N MISSOURI A N
ARKANSAS A B LOUISIANA A B WISCONSIN N N
ILLINOIS A B MISSISSIPPI A B MICHIGAN B N
INDIANA N B OHIO N N KENTUCKY A B
TENNESSEE A B ALABAMA A B NEW YORK B N
VERMONT B N NEW HAMP B A MAINE B A
MASS B A CONN B A RHODE IS B A
PENN B N NEW JERSEY B N W VIRGINIA N N
MARYLAND B N DELAWARE B N VIRGINIA N N
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE A A
AK ALEUTIAN N A AK WESTERN A A AK INT BSN A A
AK S INT A A AK SO COAST A 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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