681
FXUS06 KWBC 101902
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 10 2023
6-10 DAY OUTLOOK FOR OCT 16 - 20 2023
TODAY’S DYNAMICAL MODEL SOLUTIONS ARE IN GOOD AGREEMENT REGARDING AN AMPLIFIED
500-HPA GEOPOTENTIAL HEIGHT PATTERN ACROSS NORTH AMERICA DURING THE 6-10 DAY
PERIOD. MID-LEVEL TROUGHS ARE FORECAST ACROSS THE CENTRAL PACIFIC AND OVER THE
EASTERN CONUS WITH THE MANUAL HEIGHT BLEND DEPICTING ASSOCIATED AREAS OF
BELOW-NORMAL HEIGHTS ACROSS SOUTHWESTERN ALASKA AND MOST OF THE EASTERN CONUS
RESPECTIVELY. CONVERSELY, AMPLIFIED RIDGING IS PREDICTED OVER THE WESTERN CONUS
WITH A BROAD AREA OF POSITIVE 500-HPA HEIGHT ANOMALIES EXTENDING THROUGH MUCH
OF CANADA AND MAINLAND AND SOUTHEAST ALASKA. THERE IS SOME UNCERTAINTY
REGARDING SHORTWAVE TROUGHING THAT IS PREDICTED TO BREAK OFF THE MEAN TROUGH
OVER THE CENTRAL PACIFIC, WITH THE ECMWF ENSEMBLE DEPICTING A MORE ROBUST
FEATURE COMPARED TO THE GEFS AND CANADIAN ENSEMBLES. THIS WOULD FAVOR A
WEAKNESS IN THE HEIGHTS DEVELOPING ACROSS THE WEST-CENTRAL CONUS ALONG WITH
INCREASED BAROCLINIC FORCING ACROSS THE GREAT PLAINS. WEAKLY POSITIVE 500-HPA
HEIGHT ANOMALIES ARE PREDICTED ACROSS HAWAII.
MEAN TROUGHING IN THE EAST FAVORS INCREASED PROBABILITIES OF BELOW-NORMAL
TEMPERATURES ACROSS MUCH OF THE EASTERN CONUS, EXTENDING THROUGH EASTERN PARTS
OF THE CENTRAL AND SOUTHERN PLAINS. THE HIGHEST PROBABILITIES (GREATER THAN 80
PERCENT) ARE INDICATED ACROSS PARTS OF THE SOUTHEAST AND FLORIDA WHERE THE GEFS
AND ECMWF REFORECAST CONSOLIDATION AND THE UNCALIBRATED ENSEMBLES INDICATE MEAN
TEMPERATURES 5 TO 10 DEG F BELOW NORMAL FOR THE PERIOD AS A WHOLE. INCREASED
CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE FAVORED ACROSS MUCH OF THE WESTERN
AND NORTH-CENTRAL CONUS UNDERNEATH ENHANCED RIDGING AND POSITIVE MID-LEVEL
HEIGHT ANOMALIES. PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE INCREASED
ACROSS MUCH OF ALASKA DUE TO ENHANCED SOUTHERLY MID-LEVEL FLOW AND POSITIVE
HEIGHT ANOMALIES ACROSS MUCH OF THE MAINLAND, WITH A SLIGHT TILT TOWARD
INCREASED BELOW-NORMAL TEMPERATURE PROBABILITIES ACROSS THE FAR WESTERN
MAINLAND AND PARTS OF THE ALEUTIANS. CHANCES FOR NEAR- TO ABOVE-NORMAL
TEMPERATURES ARE INCREASED OVER HAWAII, CONSISTENT WITH THE GEFS AND ECMWF
REFORECAST CONSOLIDATION TOOLS.
THE ORIENTATION OF THE TROUGH OVER THE EAST FAVORS PREDOMINATELY NORTHWESTERLY
MID-LEVEL FLOW ACROSS MUCH OF THE EASTERN HALF OF THE CONUS AND INCREASED
CHANCES FOR NEAR- TO BELOW-NORMAL PRECIPITATION. THE ONLY EXCEPTION IS NEAR THE
IMMEDIATE MID-ATLANTIC AND NORTHEAST COASTS, WHERE A LINGERING SURFACE LOW
PRESSURE SYSTEM EARLY IN THE PERIOD TILTS THE ODDS SLIGHTLY TOWARD ABOVE-NORMAL
PRECIPITATION. THE MAIN SOURCE OF UNCERTAINTY LIES IN THE AMPLITUDE OF
SHORTWAVE TROUGHING FORECAST TO DIG THROUGH THE WESTERN CONUS AROUND THE MIDDLE
OF THE PERIOD. THE ECMWF ENSEMBLE IS MORE ROBUST WITH THIS FEATURE, LEADING TO
A MORE EXPANSIVE REGION OF ABOVE-NORMAL PRECIPITATION PROBABILITIES ACROSS THE
WESTERN AND CENTRAL CONUS IN THE CORRESPONDING REFORECAST TOOL. THE GEFS
REFORECAST TOOL IS MORE TONED DOWN, WITH LARGER PROBABILITIES OF BELOW-NORMAL
PRECIPITATION PERSISTING ACROSS THE SOUTHWEST, AND WEAK ABOVE-NORMAL
PRECIPITATION PROBABILITIES EXTENDING FROM THE PACIFIC NORTHWEST THROUGH THE
GREAT PLAINS. TODAY’S FORECAST LEANS TOWARD INCREASED CHANCES FOR ABOVE-NORMAL
PRECIPITATION ACROSS THE GREAT PLAINS, ALTHOUGH PROBABILITIES ARE NOT AS HIGH
AS DEPICTED IN THE ECMWF. LARGER PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION
ARE INDICATED IN THE FORECAST ALONG THE WEST COAST, WITH ENHANCED NEAR-TO
BELOW-NORMAL PRECIPITATION CHANCES ACROSS THE SOUTHWEST. STRONG ONSHORE FLOW
AND SURFACE LOW PRESSURE FAVOR INCREASED CHANCES OF ABOVE-NORMAL PRECIPITATION
ACROSS EASTERN ALASKA, WITH BELOW-NORMAL PRECIPITATION CHANCES INCREASED CLOSER
TO THE BACKSIDE OF THE TROUGH AXIS ACROSS THE WESTERN MAINLAND AND THE
ALEUTIANS. NEAR- TO BELOW-NORMAL PRECIPITATION PROBABILITIES ARE FORECAST
ACROSS HAWAII GIVEN THE PREDICTED RIDGING.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON
DAY 8, 30% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF
TODAY'S OPERATIONAL 0Z ECMWF 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 OF 5, DUE TO GOOD
MODEL AGREEMENT ON THE 500-HPA FLOW PATTERN ACROSS NORTH AMERICA, OFFSET BY
UNCERTAINTY RELATING TO THE MAGNITUDE OF A SHORTWAVE TROUGH FORECAST TO MOVE
ACROSS THE WESTERN CONUS.
8-14 DAY OUTLOOK FOR OCT 18 - 24 2023
A GENERALLY PERSISTENT 500-HPA GEOPOTENTIAL HEIGHT PATTERN IS FORECAST DURING
WEEK-2 RELATIVE TO THE 6-10 DAY PERIOD. EARLY IN THE PERIOD THERE IS SOME
UNCERTAINTY RELATED TO SHORTWAVE TOUCHING ACROSS THE CENTRAL CONUS. A MORE
AMPLIFIED FEATURE, AS IN THE ECMWF, MAY RESULT IN A BRIEF PERIOD OF UPSTREAM
TRANSIENT RIDGING ACROSS PARTS OF THE EASTERN CONUS, ALTHOUGH BOTH THE ECMWF
AND GEFS TREND TO MORE LONGWAVE TROUGHING OVER THE EASTERN CONUS BY THE END OF
WEEK-2. RIDGING REMAINS FORECAST ACROSS MUCH OF THE WESTERN CONUS, WITH
TROUGHING OVER THE CENTRAL PACIFIC, TO THE SOUTH OF ALASKA. TODAY’S MANUAL
500-HPA HEIGHT BLEND OF THE WEEK-2 PERIOD DEPICTS NEAR- TO BELOW-NORMAL HEIGHTS
ACROSS THE EASTERN CONUS AND ABOVE-NORMAL HEIGHTS OVER THE WESTERN AND
NORTH-CENTRAL CONUS, AND EXTENDING NORTHWARD THROUGH WESTERN CANADA AND ALASKA.
GENERALLY, ABOVE-NORMAL MID-LEVEL HEIGHTS ARE PREDICTED ACROSS HAWAII, ALTHOUGH
DECREASING HEIGHTS ARE POSSIBLE LATER IN THE PERIOD ACROSS THE NORTHERN ISLANDS
AS THE CENTRAL PACIFIC TROUGHING BEGINS TO DIP SOUTHWARD.
THERE ARE ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES ACROSS MUCH OF
THE WESTERN AND NORTH-CENTRAL CONUS. ALTHOUGH RELATIVELY WARMER TEMPERATURES
MAY BUILD INTO PARTS OF THE EAST EARLY IN WEEK-2 DEPENDING ON THE DEGREE OF
SOUTHWESTERLY MID-LEVEL FLOW, A GENERAL TREND TOWARD A COLDER PATTERN IS MORE
LIKELY BY THE END OF THE PERIOD GIVEN THE FORECAST LONGWAVE TROUGH AXIS
PREDICTED TO DEVELOP OVER EASTERN NORTH AMERICA. THIS IS SUPPORTED BY MOST OF
THE UNCALIBRATED TEMPERATURE TOOLS AND THE ANALOG GUIDANCE. THEREFORE,
PROBABILITIES FOR BELOW-NORMAL TEMPERATURES ARE INCREASED ACROSS MUCH OF THE
EAST, WITH THE HIGHEST PROBABILITIES (GREATER THAN 50 PERCENT) INDICATED OVER
THE SOUTHERN MID-ATLANTIC, SOUTHEAST, AND FLORIDA. NEAR TO ABOVE-NORMAL
TEMPERATURE PROBABILITIES ARE ELEVATED ACROSS THE NORTHERN OHIO VALLEY AND
NORTHEAST CONSISTENT WITH THE GEFS AND ECMWF REFORECAST TOOLS. IN ALASKA,
CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE INCREASED ACROSS MOST OF THE STATE
DUE TO INCREASED SOUTHERLY MID-LEVEL FLOW. NEAR- TO ABOVE-NORMAL TEMPERATURES
ARE FAVORED ACROSS MOST OF HAWAII, WITH A SLIGHT TILT TOWARD INCREASED
BELOW-NORMAL TEMPERATURE PROBABILITIES ACROSS THE SOUTHWESTERN PORTION OF THE
BIG ISLAND DUE IN PART TO BELOW-NORMAL SEA SURFACE TEMPERATURES.
THE WEEK-2 PRECIPITATION FORECAST REMAINS UNCERTAIN GIVEN THE DIFFERENCES IN
THE MODELS REGARDING SHORTWAVE TROUGHING ACROSS THE WESTERN AND CENTRAL CONUS
EARLY IN THE PERIOD. AS IN THE 6-10 DAY OUTLOOK, THE ECMWF REFORECAST TOOL HAS
MUCH HIGHER PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION ACROSS THE CENTRAL
CONUS, MISSISSIPPI VALLEY, AND SOUTHEAST COMPARED TO THE GEFS WHICH HAS A
SLIGHT TILT TOWARD INCREASED BELOW-NORMAL PRECIPITATION PROBABILITIES OVER SOME
OF THESE AREAS. A SLIGHT TILT TOWARD WEAK ABOVE-NORMAL PRECIPITATION
PROBABILITIES IS HIGHLIGHTED ACROSS THE GREAT PLAINS, AND EXTENDING INTO PARTS
OF THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST IN TODAY’S OUTLOOK. RELATIVELY
DRIER CONDITIONS ARE FORECAST ACROSS THE WEST AS THE POTENTIAL SHORTWAVE TROUGH
MOVES FURTHER INLAND FAVORING INCREASED BELOW-NORMAL PRECIPITATION
PROBABILITIES FOR MUCH OF THE REGION. THE EXCEPTION IS OVER PARTS OF THE
NORTHWEST, WHERE NEAR- TO ABOVE-NORMAL PRECIPITATION CHANCES REMAIN ELEVATED.
THE LONGWAVE TROUGHING FORECAST TO DEVELOP OVER EASTERN NORTH AMERICA FAVORS
INCREASED CHANCES FOR BELOW-NORMAL PRECIPITATION ACROSS PORTIONS OF THE GREAT
LAKES AND NORTHEAST CONSISTENT WITH THE ANALOG GUIDANCE AND THE UNCALIBRATED
GEFS AND CANADIAN ENSEMBLES. FURTHER SOUTH, SIGNALS ARE MORE MIXED, LEADING TO
A NEAR-NORMAL PRECIPITATION FORECAST TO ADDRESS THE UNCERTAINTY. ABOVE-NORMAL
PRECIPITATION PROBABILITIES ARE FORECAST TO REMAIN ELEVATED ACROSS MOST OF
ALASKA DUE TO THE AFOREMENTIONED TROUGHING AND ENHANCED SOUTHERLY FLOW, WITH
AREAS OF NEAR- TO BELOW-NORMAL PRECIPITATION FORECAST ON THE BACKSIDE OF THE
TROUGH ACROSS THE SOUTHWESTERN MAINLAND AND THE ALEUTIANS. THIS SAME TROUGH
FAVORS AN INCREASE IN ABOVE-NORMAL PRECIPITATION CHANCES ACROSS NORTHERN HAWAII
DURING WEEK-2, WITH BELOW-NORMAL PRECIPITATION REMAINING FAVORED ACROSS THE
SOUTHERN HAWAII ISLANDS.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 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 30% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO GOOD
MODEL AGREEMENT ON A PERSISTENT 500-HPA FLOW PATTERN ACROSS NORTH AMERICA,
OFFSET BY CONSIDERABLE TOOL DISAGREEMENT REGARDING THE TEMPERATURE AND
PRECIPITATION FORECAST, PARTICULARLY ACROSS THE CENTRAL AND EASTERN CONUS.
FORECASTER: THOMAS COLLOW
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:
20081001 - 20051024 - 20001008 - 19870920 - 19551015
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:
20081002 - 20051023 - 19870919 - 20010924 - 20071012
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 16 - 20 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A N IDAHO A A NEVADA A N
W MONTANA A A E MONTANA A A WYOMING A A
UTAH A B ARIZONA A B COLORADO A N
NEW MEXICO A N N DAKOTA A N S DAKOTA N A
NEBRASKA N A KANSAS B A OKLAHOMA B A
N TEXAS B A S TEXAS B A W TEXAS A A
MINNESOTA A B IOWA B N MISSOURI B N
ARKANSAS B N LOUISIANA B N WISCONSIN N B
ILLINOIS B N MISSISSIPPI B N MICHIGAN N B
INDIANA B N OHIO B N KENTUCKY B N
TENNESSEE B B ALABAMA B B NEW YORK B N
VERMONT B B NEW HAMP B N MAINE N B
MASS B N CONN B N RHODE IS B A
PENN B N NEW JERSEY B N W VIRGINIA B N
MARYLAND B N DELAWARE B N VIRGINIA B N
N CAROLINA B N S CAROLINA B B GEORGIA B B
FL PNHDL B B FL PENIN B B AK N SLOPE A A
AK ALEUTIAN N B AK WESTERN A B AK INT BSN A A
AK S INT A A AK SO COAST A A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 18 - 24 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A B NRN CALIF A B
SRN CALIF A B IDAHO A B NEVADA A B
W MONTANA A N E MONTANA A N WYOMING A N
UTAH A B ARIZONA A B COLORADO A A
NEW MEXICO A N N DAKOTA A N S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA N A
N TEXAS N A S TEXAS A A W TEXAS A A
MINNESOTA A N IOWA A N MISSOURI N N
ARKANSAS N A LOUISIANA N A WISCONSIN A B
ILLINOIS N N MISSISSIPPI B N MICHIGAN A B
INDIANA N B OHIO N N KENTUCKY B N
TENNESSEE B N ALABAMA B N NEW YORK N N
VERMONT N N NEW HAMP N N MAINE A N
MASS N N CONN N N RHODE IS N N
PENN N N NEW JERSEY B N W VIRGINIA B N
MARYLAND B N DELAWARE B N VIRGINIA B N
N CAROLINA B N S CAROLINA B N GEORGIA B N
FL PNHDL B A FL PENIN B A AK N SLOPE A A
AK ALEUTIAN N B AK WESTERN A N AK INT BSN A A
AK S INT A A AK SO COAST A A AK PNHDL A A
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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