079
FXUS06 KWBC 171902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE OCTOBER 17 2023
6-10 DAY OUTLOOK FOR OCT 23 - 27 2023
THE 500-HPA HEIGHT PATTERN REMAINS AMPLIFIED AND PROGRESSIVE ACROSS THE
FORECAST DOMAIN TODAY. NEGATIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST OFF THE
NORTHEASTERN CONTIGUOUS U.S. (CONUS) COAST, OVER THE WEST, AND NORTHWEST OF
HAWAII. POSITIVE 500-HPA HEIGHT ANOMALIES ARE FAVORED ACROSS TWO REGIONS,
CENTERED ACROSS THE OHIO VALLEY AND ACROSS ALASKA RESPECTIVELY. THE WAVELENGTHS
OF THIS PATTERN ARE QUITE PROGRESSIVE AND SHORT DURING THE PERIOD. THE OVERALL
HEIGHT ANOMALIES HAVE BECOME MORE AMPLIFIED RELATIVE TO YESTERDAY.
WITH MID-LEVEL TROUGHING ACROSS MUCH OF THE WESTERN CONUS AND A MORE AMPLIFIED
PATTERN, BELOW-NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE WEST. FURTHER
EAST, ABOVE-NORMAL TEMPERATURES ARE FAVORED FROM THE PLAINS TO THE APPALACHIANS
BENEATH STRONG RIDGING. ASSOCIATED WITH THE RIDGING IS SURFACE HIGH PRESSURE
OVER THE SOUTHEAST ENHANCING RETURN FLOW OFF THE ANOMALOUSLY WARM GULF OF
MEXICO INTO THE CENTRAL CONUS FURTHER STRENGTHENING THE CHANCES FOR
ABOVE-NORMAL TEMPERATURES. ALONG THE IMMEDIATE EASTERN SEABOARD, NEAR-NORMAL
TEMPERATURES ARE FAVORED AS A DEPARTING TROUGH MAY BRING LINGERING BELOW-NORMAL
TEMPERATURES EARLY IN THE PERIOD BEFORE TEMPERATURES WARM BY THE START OF
WEEK-2. IN ALASKA, THE WARMING TREND CONTINUES TODAY ACROSS MUCH OF THE STATE
WITH MUCH OF THE ALEUTIANS AND MAINLAND FAVORED TO HAVE ABOVE-NORMAL
TEMPERATURES. LINGERING CHANCES FOR BELOW-NORMAL TEMPERATURES ARE FORECAST
ACROSS PARTS OF SOUTHEAST ALASKA. IN HAWAII, ABOVE-NORMAL TEMPERATURES ARE
GENERALLY FAVORED WITH ABOVE-NORMAL SEA SURFACE TEMPERATURES NORTH OF THE
STATE.
MID-LEVEL TROUGHING ACROSS THE WEST BRINGS GENERALLY UNSETTLED WEATHER TO MUCH
OF THE REGION WITH INCREASED CHANCES FOR ABOVE-NORMAL PRECIPITATION TO MUCH OF
THE WEST. THE ECMWF REFORECAST IS PARTICULARLY BULLISH ON ABOVE-NORMAL
PRECIPITATION DURING THE PERIOD WITH CHANCES EXCEEDING 70% IN CLIMATOLOGICALLY
DRIER REGIONS. ONE EXCEPTION IS ACROSS THE PACIFIC NORTHWEST WHERE NEAR-NORMAL
IS FAVORED DUE TO CLIMATOLOGICALLY WETTER CONDITIONS AND BEING BEHIND THE
TROUGH AXIS. FURTHER EAST, ACROSS THE PLAINS AND MISSISSIPPI VALLEY, STRONG
RETURN FLOW FROM THE GULF OF MEXICO IS FAVORED TO BRING ABOVE-NORMAL
PRECIPITATION TO THE REGION. A FURTHER SOURCE OF MOISTURE IS THE POTENTIAL FOR
A TROPICAL SYSTEM TO FORM IN THE EAST PACIFIC AND BRING INCREASED MID-LEVEL
MOISTURE TO PARTS OF THE CENTRAL CONUS DURING THE 6 TO 10 DAY PERIOD. WHILE
ACROSS THE SOUTHEAST, MID-ATLANTIC, AND NEW ENGLAND BELOW-NORMAL PRECIPITATION
IS FAVORED DUE TO STRONG SURFACE HIGH PRESSURE AND MID-LEVEL RIDGING FORECAST.
IN ALASKA, ABOVE-NORMAL PRECIPITATION IS FAVORED ACROSS THE NORTHERN TWO-THIRDS
OF THE STATE. BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS THE ALEUTIANS AND
SOUTHEAST ALASKA WHERE MID-LEVEL RIDGING IS FORECAST TO REDUCE ONSHORE FLOW. IN
HAWAII, ABOVE-NORMAL PRECIPITATION IS FAVORED ACROSS THE WESTERN ISLANDS WITH
BELOW-NORMAL PRECIPITATION FAVORED CLOSER TO POSITIVE HEIGHT ANOMALIES FOR THE
BIG ISLAND.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 25% OF TODAY'S 6Z 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: AVERAGE, 3 OUT 5, A FAST MOVING
PATTERN ALONG WITH LARGE CHANGES FROM YESTERDAY REDUCE CONFIDENCE OFFSET BY
FAIR AGREEMENT BETWEEN MODEL GUIDANCE.
8-14 DAY OUTLOOK FOR OCT 25 - 31 2023
THE 8 TO 14 DAY MID-LEVEL HEIGHT PATTERN CONTINUES TO BE QUITE PROGRESSIVE. AT
THE ONSET OF THE PERIOD, NEGATIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST ACROSS
THE WEST WITH POSITIVE 500-HPA HEIGHT ANOMALIES FORECAST ACROSS THE EAST. THE
NEGATIVE 500-HPA HEIGHT ANOMALIES ACROSS THE WEST ARE EXPECTED TO PROGRESS AND
WEAKEN AS THE CENTER OF THE NEGATIVE ANOMALIES MOVES INTO THE PLAINS. AT THE
SAME TIME, THE POSITIVE 500-HPA HEIGHT ANOMALIES ACROSS THE EASTERN CONUS ARE
FORECAST TO WEAKEN AND SHIFT FURTHER EAST. BY THE END OF THE PERIOD, A MORE
ZONAL FLOW PATTERN IS FORECAST ACROSS THE MID-LEVELS. THIS IS EVIDENT IN THE
500-HPA MANUAL HEIGHT BLEND WITH LOWER ANOMALIES ACROSS THE CONUS. MEANWHILE IN
ALASKA, POSITIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST ACROSS MUCH OF THE
STATE. THE FORECAST IS SLIGHTLY LESS AMPLIFIED BUT IN A SIMILAR LOCATION AS
YESTERDAY. IN HAWAII, NEAR TO ABOVE-NORMAL MID-LEVEL HEIGHTS ARE FORECAST
ACROSS THE CENTRAL PACIFIC.
THE FORECAST FOR WEEK-2 TEMPERATURES IS FAIRLY CONSISTENT WITH YESTERDAY’S
ACROSS MUCH OF THE COUNTRY. ABOVE-NORMAL TEMPERATURES ARE FAVORED ACROSS MUCH
OF THE EASTERN HALF OF THE CONUS WITH THE STRONGEST PROBABILITIES ALONG IN THE
MISSISSIPPI VALLEY. THIS AREA IS LIKELY TO SEE THE STRONGEST RETURN FLOW
THROUGHOUT THE PERIOD AND ABOVE-NORMAL SEA SURFACE TEMPERATURES IN THE GULF OF
MEXICO CONTRIBUTE TO ABOVE-NORMAL TEMPERATURES BEING STRONGLY FAVORED. ACROSS
THE WEST, TROUGHING, PARTICULARLY EARLY IN THE PERIOD, CONTRIBUTES TO MUCH OF
THE REGION FAVORED TO SEE BELOW-NORMAL TEMPERATURES DURING THE PERIOD.
MEANWHILE, IN ALASKA, MUCH OF THE STATE IS FAVORED TO HAVE ABOVE-NORMAL
TEMPERATURES DURING WEEK-2 WITH STRONG POSITIVE 500-HPA HEIGHT ANOMALIES
FORECAST ACROSS THE STATE BRINGING RIDGING TO MUCH OF THE STATE. THE EXCEPTION
IS IN PARTS OF SOUTHEAST ALASKA WHERE NEAR TO BELOW-NORMAL TEMPERATURES REMAIN
FAVORED. IN HAWAII, ABOVE-NORMAL TEMPERATURES ARE FAVORED WITH NEAR TO
ABOVE-NORMAL SEA SURFACE TEMPERATURES AND SOUTHERLY MID-LEVEL FLOW AHEAD OF A
WEAK MID-LEVEL TROUGH TO THE NORTH.
ABOVE-NORMAL PRECIPITATION IS GENERALLY FAVORED ACROSS MUCH OF THE COUNTRY
DURING THE WEEK-2 PERIOD. MID-LEVEL TROUGHING ACROSS THE WEST CONTINUES TO
BRING CHANCES FOR GENERALLY UNSETTLED WEATHER TO MUCH OF THE REGION INCREASING
CHANCES FOR ABOVE-NORMAL PRECIPITATION. AHEAD OF THE TROUGH ACROSS THE PLAINS
AND MISSISSIPPI VALLEY ABOVE-NORMAL PRECIPITATION IS AGAIN FAVORED DUE TO
ENHANCED RETURN FLOW OFF THE GULF OF MEXICO. BELOW-NORMAL PRECIPITATION IS
FAVORED ALONG THE EAST COAST, BENEATH POSITIVE 500-HPA HEIGHT ANOMALIES AND
ASSOCIATED RIDGING. IN ALASKA, ABOVE-NORMAL PRECIPITATION REMAINS FORECAST
ACROSS MUCH OF THE MAINLAND WITH SLIGHTLY ONSHORE FLOW INTO PORTIONS OF THE
WESTERN MAINLAND. LINGERING CHANCES FOR BELOW-NORMAL REMAIN FAVORED IN PARTS OF
SOUTHEAST ALASKA AHEAD OF THE RIDGE AXIS. IN HAWAII, BELOW-NORMAL PRECIPITATION
IS FAVORED ACROSS MUCH OF THE STATE WITH STRONGER POSITIVE 500-HPA HEIGHTS
BUILDING ACROSS THE ISLANDS.
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: BELOW-AVERAGE, 3 OUT OF 5, QUICK
CHANGES IN MODEL GUIDANCE AND SHORT WAVELENGTHS IN THE 500-HPA HEIGHT PATTERN
REDUCE CONFIDENCE OFFSET BY FAIR AGREEMENT AMONG THE TOOLS FOR THE PERIOD.
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
OCTOBER 19.
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:
19581027 - 20081003 - 19791026 - 19541019 - 19881005
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:
19581028 - 20081003 - 19541019 - 20031006 - 19921029
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 23 - 27 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B N OREGON B A NRN CALIF B N
SRN CALIF B A IDAHO B A NEVADA B A
W MONTANA B A E MONTANA B A WYOMING B A
UTAH B A ARIZONA B A COLORADO N A
NEW MEXICO N A N DAKOTA N A S DAKOTA N A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN A A
ILLINOIS A A MISSISSIPPI A A MICHIGAN A A
INDIANA A A OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA A N NEW YORK A B
VERMONT A B NEW HAMP A B MAINE A B
MASS N B CONN N B RHODE IS N B
PENN A B NEW JERSEY N B W VIRGINIA A B
MARYLAND A B DELAWARE N B VIRGINIA A B
N CAROLINA N B S CAROLINA A B GEORGIA A B
FL PNHDL A B FL PENIN A B AK N SLOPE A A
AK ALEUTIAN A N AK WESTERN A A AK INT BSN A A
AK S INT A N AK SO COAST A N AK PNHDL B B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 25 - 31 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B B OREGON B N NRN CALIF B N
SRN CALIF B N IDAHO B A NEVADA B N
W MONTANA B A E MONTANA B A WYOMING B A
UTAH B A ARIZONA B A COLORADO B A
NEW MEXICO N A N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS B A OKLAHOMA N A
N TEXAS A A S TEXAS A A W TEXAS N A
MINNESOTA B A IOWA N A MISSOURI N A
ARKANSAS A A LOUISIANA A A WISCONSIN N A
ILLINOIS N A MISSISSIPPI A A MICHIGAN A A
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A N NEW YORK A N
VERMONT A N NEW HAMP A B MAINE A B
MASS A B CONN A B RHODE IS A B
PENN A N NEW JERSEY A B W VIRGINIA A N
MARYLAND A B DELAWARE A B 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 A N
AK ALEUTIAN A N AK WESTERN A A AK INT BSN A N
AK S INT A N AK SO COAST A N AK PNHDL N 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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