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FXUS06 KWBC 161902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT MON OCTOBER 16 2023
6-10 DAY OUTLOOK FOR OCT 22 - 26 2023
THE 500-HPA HEIGHT PATTERN REMAINS AMPLIFIED AND PROGRESSIVE ACROSS THE
FORECAST DOMAIN TODAY. SINCE FRIDAY, THE 500-HPA HEIGHT ANOMALY GUIDANCE HAS
COMPLETED AN ENTIRE PHASE SHIFT. NEGATIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST
OFF THE CONTIGUOUS U.S. (CONUS) EAST COAST, OVER THE WEST, AND NORTHWEST OF
HAWAII. POSITIVE 500-HPA HEIGHT ANOMALIES ARE FAVORED ACROSS TWO REGIONS, THE
MISSISSIPPI VALLEY AND ACROSS ALASKA RESPECTIVELY. THE WAVELENGTHS OF THIS
PATTERN ARE QUITE PROGRESSIVE AND SHORT DURING THE PERIOD.
WITH MID-LEVEL TROUGHING ALONG BOTH COASTS OF THE CONUS AT THE START OF THE
PERIOD, NEAR- TO BELOW-NORMAL TEMPERATURES ARE FAVORED ALONG MUCH OF THE
EASTERN SEABOARD AND IN THE WEST COAST STATES AND NORTH INTO SOUTHEAST ALASKA.
SURFACE HIGH PRESSURE IN THE EASTERN CONUS IS LIKELY TO HELP PROMOTE NORTHERLY
FLOW INTO PORTIONS OF THE EASTERN CONUS. CONVERSELY, IN THE MISSISSIPPI VALLEY
AND PLAINS, ABOVE-NORMAL TEMPERATURES ARE FAVORED WITH SOUTHERLY FLOW INTO THE
REGION. IN PARTS OF WESTERN ALASKA, ABOVE-NORMAL TEMPERATURES ARE FAVORED TODAY
WITH STRONGER MID-LEVEL RIDGING PUSHING BELOW-NORMAL TEMPERATURES FURTHER EAST
RELATIVE TO YESTERDAY. 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 LATE IN THE 6 TO 10 DAY PERIOD. WHILE
ACROSS THE SOUTHEAST, MID-ATLANTIC, AND OHIO VALLEY, 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,
SOUTHERN MAINLAND, AND SOUTHEAST ALASKA WHERE MID-LEVEL RIDGING IS FORECAST TO
REDUCE ONSHORE FLOW INTO THE STATE.
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: BELOW-AVERAGE, 2 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 24 - 30 2023
AS WITH THE 6 TO 10 DAY, THE WEEK-2 500-HPA HEIGHT FORECAST CONTINUES TO BE
AMPLIFIED. AT THE ONSET OF THE PERIOD, POSITIVE 500-HPA HEIGHT ANOMALIES ARE
FAVORED ACROSS THE EASTERN CONUS, AND ACROSS NORTHWEST NORTH AMERICA. NEGATIVE
500-HPA HEIGHT ANOMALIES ARE FAVORED ACROSS THE WESTERN CONUS AND NORTHWEST OF
HAWAII. DURING THE PERIOD, THE TROUGH ACROSS THE WESTERN CONUS IS FORECAST TO
PROGRESS NORTHEAST INTO CANADA. MEANWHILE, THE RIDGE OVER THE EASTERN CONUS IS
FORECAST TO REMAIN. OVERALL, THE MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT OF
THE PATTERN DURING WEEK-2 BUT IT REMAINS A CHALLENGING ENVIRONMENT TO PREDICT
DUE TO THE RAPID CHANGES SEEN IN MODEL GUIDANCE OVER THE WEEKEND.
THE FORECAST FOR WEEK-2 TEMPERATURES CONTINUES TO EVOLVE QUICKLY ACROSS NORTH
AMERICA RELATIVE TO THE 6 TO 10 DAY AND PREVIOUS FORECASTS. ABOVE-NORMAL
TEMPERATURES ARE FAVORED ACROSS MUCH OF THE EASTERN TWO-THIRDS OF THE CONUS
WITH THE STRONGEST PROBABILITIES ALONG THE WESTERN GULF OF MEXICO COAST. 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. THE TROUGH IS FORECAST TO
ORIGINATE IN CANADA AND BRING BELOW-NORMAL TEMPERATURES. MEANWHILE, IN ALASKA,
AS WITH THE 6 TO 10 DAY TOOLS ARE BRINGING MUCH WARMER CONDITIONS TO MUCH OF
THE STATE BY WEEK-2. 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.
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. THE HIGHEST CHANCES (>50%) STRETCH FROM
UTAH INTO PARTS OF THE NORTHERN PLAINS. A SECOND AREA OF HIGHEST CHANCES IS IN
PARTS OF THE SOUTHERN PLAINS WITH LOWER CHANCES EXTENDING INTO THE MISSISSIPPI
AND OHIO VALLEYS. A TROPICAL SYSTEM IN THE EAST PACIFIC MAY ENHANCE MOISTURE
INTO PARTS OF THE PLAINS BRINGING INCREASED CHANCES FOR ABOVE-NORMAL
PRECIPITATION TO THIS REGION. FURTHER EAST, 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 THE NORTHERN TWO-THIRDS OF THE MAINLAND AND NOW EXTENDING FURTHER SOUTH
TO THE GULF OF ALASKA. A QUICK PROGRESSION OF THE MID-LEVEL RIDGE BRINGS
INCREASED CHANCES FOR ONSHORE FLOW TO DEVELOP INTO PARTS OF THE SOUTHERN
MAINLAND COAST. LINGERING CHANCES FOR BELOW-NORMAL REMAIN FAVORED IN PARTS OF
SOUTHEAST ALASKA. IN HAWAII, ABOVE-NORMAL PRECIPITATION IS FAVORED ON THE
WESTERN ISLANDS CLOSER TO A MID-LEVEL TROUGH. BELOW-NORMAL IS FAVORED ACROSS
THE BIG ISLAND NEARER POSITIVE 500-HPA HEIGHT ANOMALIES.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 35% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 25% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: BELOW-AVERAGE, 2 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:
20081002 - 19581026 - 19791026 - 19881005 - 20051025
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:
20081003 - 19581027 - 19791026 - 19921029 - 19881004
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 22 - 26 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B A
SRN CALIF B A IDAHO N A NEVADA N A
W MONTANA N A E MONTANA N A WYOMING N A
UTAH N A ARIZONA N A COLORADO A A
NEW MEXICO A A N DAKOTA A A S DAKOTA A 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 N LOUISIANA A N WISCONSIN A A
ILLINOIS A A MISSISSIPPI A N MICHIGAN A N
INDIANA A N OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A B NEW YORK N B
VERMONT N N NEW HAMP N B MAINE N N
MASS N B CONN B B RHODE IS B B
PENN N B NEW JERSEY B B W VIRGINIA N B
MARYLAND B B DELAWARE B B VIRGINIA B B
N CAROLINA B B S CAROLINA B B GEORGIA N B
FL PNHDL N B FL PENIN N B AK N SLOPE A A
AK ALEUTIAN A B AK WESTERN A A AK INT BSN N A
AK S INT N N AK SO COAST N N AK PNHDL B B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 24 - 30 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B N OREGON B N NRN CALIF B A
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 B A S DAKOTA N A
NEBRASKA N A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA N 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 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 B
N CAROLINA A 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 A AK SO COAST A A 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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