261
FXUS06 KWBC 261941
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU OCTOBER 26 2023
6-10 DAY OUTLOOK FOR NOV 01 - 05 2023
THE 6-10 DAY MEAN 500-HPA HEIGHT FORECASTS FROM THE LATEST ECMWF, GFS, AND
CANADIAN ENSEMBLE MEANS ARE IN FAIRLY GOOD AGREEMENT WITH REGARD TO THE
SYNOPTIC PATTERN WITH MODERATE TROUGHING OVER THE NORTH PACIFIC, CONTINUED
ANOMALOUS RIDGING ACROSS ALASKA EXTENDING WEAKLY SOUTHEASTWARD INTO THE WESTERN
CONUS, AND A TROUGH OVER THE EASTERN CONTIGUOUS U.S. (CONUS) EXTENDING
NORTHWARD INTO NORTHEASTERN CANADA. THE MOST NOTABLE MODEL DISCREPANCIES REGARD
THE EASTWARD EXTENT OF SUBNORMAL 500-HPA HEIGHTS FROM THE CENTRAL NORTH
PACIFIC. THE OPERATIONAL GFS AND GEFS BRING LOWER HEIGHTS INTO THE PACIFIC
NORTHWEST WHILE MOST OTHER GUIDANCE KEEPS 500-HPA SLIGHTLY ABOVE NORMAL IN THE
NORTHWEST. TELECONNECTIONS FAVOR KEEPING ANOMALOUSLY LOW HEIGHTS OFFSHORE WEST
OF THE CONUS.
THE SYNOPTIC PATTERN IS FAVORABLE FOR AN ARCTIC AIR SURGE MOVING SOUTHWARD OUT
OF CANADA, RESULTING IN BELOW-NORMAL TEMPERATURES BEING FAVORED FOR MUCH OF THE
CENTRAL AND EASTERN CONUS. TEMPERATURES WITH THIS FEATURE WILL BE UNSEASONABLY
COLD, BUT THE COLD SPELL IS EXPECTED TO BE SHORT-LIVED. 500-HPA HEIGHTS ARE
FORECAST TO REBOUND LATER IN THE PERIOD, ALLOWING SURFACE HIGH PRESSURE TO
SLIDE EASTWARD INTO THE ATLANTIC, PULLING WARMER AIR INTO THE CENTRAL AND
EASTERN CONUS FROM THE SOUTH. STILL, PROBABILITIES OF BELOW-NORMAL TEMPERATURES
FOR THE 5-DAY PERIOD AS A WHOLE EXCEED 70 PERCENT OVER PORTIONS OF SOUTH TEXAS,
WITH ODDS TOPPING 60 PERCENT ACROSS A BROAD AREA FROM THE SOUTHERN GREAT PLAINS
NORTHEASTWARD INTO THE MID-ATLANTIC AND NORTHEASTERN CONUS. FROM THE HIGH
PLAINS EASTWARD, ONLY SOUTHERN FLORIDA IS EXPECTED TO LARGELY MISS THE COLD AIR
OUTBREAK, WITH NEAR TO ABOVE-NORMAL TEMPERATURES FORECAST ACROSS MOST OF THE
PENINSULA. FARTHER WEST, ABOVE-NORMAL 500-HPA HEIGHTS ARE EXPECTED TO KEEP
TEMPERATURES ABOVE-NORMAL OVER THE CONUS WEST OF THE ROCKIES.
AMPLIFIED RIDGING OVER WESTERN NORTH AMERICA RESULTS IN SOUTHERLY FLOW ALOFT
AND ENHANCED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES THROUGHOUT ALASKA.
MEANWHILE, WEAKLY ABOVE-NORMAL SEA SURFACE TEMPERATURES IN THE HAWAII REGION
RESULT IN A SLIGHT TILT TOWARDS ABOVE-NORMAL TEMPERATURES FOR THE ISLANDS.
EAST OF THE CENTRAL NORTH PACIFIC MID-LEVEL TROUGH, CYCLONICALLY-CURVED AND
DIFFLUENT MID-LEVEL FLOW INTO THE PACIFIC NORTHWEST FAVORS SURPLUS
PRECIPITATION OVER THE NORTHWEST QUARTER OF THE CONUS, WITH ODDS FOR
ABOVE-NORMAL AMOUNTS EXCEEDING 50 PERCENT FROM NORTHERN CALIFORNIA NORTHWARD TO
THE CANADIAN BORDER. FARTHER SOUTH AND EAST, DRIER THAN NORMAL CONDITIONS ARE
FAVORED FOR MOST OF THE CONUS IN THE WAKE OF THE COLD AIR SURGE UNDER
ANTI-CYCLONIC MID-LEVEL FLOW. THE FLORIDA PENINSULA AND COASTAL SECTIONS OF
GEORGIA AND SOUTH CAROLINA ARE EXCEPTIONS, WHERE TROPICAL OR SUB-TROPICAL
MOISTURE MAY ENHANCE RAINFALL LATER IN THE PERIOD, LEADING TO SLIGHTLY
ABOVE-NORMAL PRECIPITATION FAVORED.
WHILE ABOVE-NORMAL 500-HPA HEIGHTS COVER ALASKA, A WEAK RELATIVE MID-LEVEL
TROUGH SHOULD BE ESTABLISHED OVER WESTERN PARTS OF THE MAINLAND AND INTO THE
ALEUTIANS., THIS INCREASES THE ODDS FOR SURPLUS PRECIPITATION IN EASTERN
MAINLAND ALASKA, BUT NEAR AND WEST OF THE MID-LEVEL TROUGH, SUBNORMAL
PRECIPITATION IS MORE LIKELY FROM THE WESTERN HALF OF THE MAINLAND WESTWARD.
SOME STORMINESS IS POSSIBLE ACROSS SOUTHEASTERN AND COASTAL SOUTH-CENTRAL
ALASKA JUST EAST OF THE MID-LEVEL TROUGH, BUT OCTOBER IS VERY WET
CLIMATOLOGICALLY IN THIS AREA, WITH NORMAL PRECIPITATION TOTALS EXCEEDING 20
INCHES IN SOME LOCATIONS. AS A RESULT, NO TILT OF THE ODDS TOWARD WETTER- OR
DRIER-THAN-NORMAL CONDITIONS HAS BEEN DETERMINED. BELOW-NORMAL PRECIPITATION IS
FAVORED FOR THE HAWAIIAN ISLANDS WITH A CONTINUED DRYING INFLUENCE FROM EL NINO
CONDITIONS.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 15% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED
ON DAY 8, 30% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, AND 50%
OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: SLIGHTLY BELOW AVERAGE, 2 OUT OF
5, DUE TO FAIR AGREEMENT AMONG MODELS ON SYNOPTIC PATTERN, OFFSET BY DIVERGING
TEMPERATURE AND PRECIPITATION GUIDANCE FROM REFORECAST AND CALIBRATED MODEL
ENSEMBLE TOOLS.
8-14 DAY OUTLOOK FOR NOV 03 - 09 2023
ACROSS THE CONUS, DYNAMICAL MODELS DEPICT A DEAMPLIFICATION OF THE 6-10 DAY
MEAN MID-LEVEL HEIGHT PATTERN FOR WEEK-2, RESULTING IN SLIGHTLY BELOW-NORMAL
500-HPA HEIGHTS ACROSS NEW ENGLAND, SOMEWHAT ABOVE-NORMAL HEIGHTS IN THE
WEST-CENTRAL AND SOUTHWESTERN CONUS, AND NEAR-NORMAL HEIGHTS ELSEWHERE. OVER
THE NORTH PACIFIC, MODEL SOLUTIONS DO NOT PULL TROUGHING AS FAR EAST AS THEY
DID YESTERDAY, KEEPING CYCLONICALLY-CURVED, DIFFLUENT MID-LEVEL FLOW OVER THE
WESTERN CONUS. ABOVE-NORMAL HEIGHTS PERSIST OVER ALASKA, WITH THE WEAK TROUGH
AXIS REMAINING ROUGHLY IN PLACE ACROSS THE WESTERN PART OF THE MAINLAND. THE 6Z
OPERATIONAL GFS PLACES A SUBSTANTIAL MID-LEVEL TROUGH OVER THE WESTERN CONUS
AND ABNORMALLY HIGH 500-HPA HEIGHTS FARTHER EAST, BUT THIS SOLUTION IS MUCH
DIFFERENT THAN THE CONSENSUS OF OTHER GUIDANCE, AND IS NOT FAVORED AT THIS TIME.
WITH A MORE ZONAL PATTERN OVER NORTH AMERICA DURING WEEK-2, THE WARMING TREND
BEGINNING LATE IN THE 6-10 DAY PERIOD SHOULD CONTINUE ACROSS MOST OF THE CONUS.
A MAJORITY OF THE CONUS IS EXPECTED TO SEE ABOVE-NORMAL TEMPERATURES, WITH THE
HIGHEST ODDS (OVER 60%) IN THE SOUTHERN HALF OF THE HIGH PLAINS, CENTRAL AND
NORTHERN CALIFORNIA, AND THE PACIFIC NORTHWEST. ENHANCED CHANCES FOR SUBNORMAL
TEMPERATURES ARE RESTRICTED TO NEW ENGLAND (UNDER BELOW-NORMAL 500-HPA HEIGHTS)
AND THE NORTHERN PLAINS (DUE TO SNOW COVER AND A FAVORABLE SET-UP FOR
RADIATIONAL COOLING). ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED FOR MUCH OF
ALASKA, BUT WEAKENING SOUTHEASTERLY FLOW AND THE POTENTIAL FOR SOME NORTHERLY
WINDS LATER WEEK-2 LEAVES NEITHER ABOVE- NOR BELOW-NORMAL TEMPERATURES FAVORED
FOR MUCH OF THE ALASKAN INTERIOR. WEAKLY ABOVE-NORMAL SEA SURFACE TEMPERATURES
IN THE HAWAII REGION RESULT IN A SLIGHT TILT TOWARDS ABOVE-NORMAL TEMPERATURES
FOR THE ISLANDS.
THE SET-UP FAVORING ABOVE-NORMAL PRECIPITATION IS FORECAST TO REMAIN IN PLACE
ACROSS THE NORTHWESTERN CONUS FOR MOST OR ALL OF WEEK-2, KEEPING ENHANCED ODDS
FOR ABOVE-NORMAL PRECIPITATION IN PLACE THERE. FARTHER EAST, WEAK MID-LEVEL
HEIGHT ANOMALIES GENERALLY PRECLUDE EXCESSIVE PRECIPITATION, BUT WEAK FEATURES
ALSO INTRODUCE A LOT OF UNCERTAINTY. MOST GUIDANCE SLIGHTLY FAVORS BELOW-NORMAL
PRECIPITATION FROM THE SOUTHWEST THROUGH THE LOWER MISSISSIPPI VALLEY, WHILE A
CONTINUED INFLUX OF ATLANTIC MOISTURE FROM THE TROPICS AND LOWER MID-LATITUDES
TILTS THE FORECAST TOWARD ABOVE-NORMAL PRECIPITATION FROM SOUTHERN NEW ENGLAND
SOUTHWARD ALONG THE EAST COAST, ESPECIALLY FROM THE EASTERN CAROLINAS SOUTHWARD
ACROSS THE FLORIDA PENINSULA. HOWEVER, THERE IS SIGNIFICANT UNCERTAINTY
INTRODUCED BY THE POTENTIAL FOR TROPICAL CYCLONE DEVELOPMENT IN THE CARIBBEAN
OR WESTERN NORTH ATLANTIC. AS SOUTHERLY FLOW OFF THE GULF OF ALASKA SUBSIDES, A
SLIGHT TILT TOWARD BELOW-NORMAL PRECIPITATION BECOMES FAVORED FOR MOST OF THE
STATE OUTSIDE SOUTHEASTERN PARTS OF THE STATE (NO TILT OF THE ODDS) AND THE
NORTHERN COASTLINE (SURPLUS PRECIPITATION WEAKLY FAVORED). BELOW-NORMAL
PRECIPITATION REMAINS FAVORED FOR CENTRAL AND SOUTHERN PARTS OF THE HAWAIIAN
ISLANDS UNDER THE CONTINUING INFLUENCE OF EL NINO CONDITIONS, BUT UNCERTAINTY
REGARDING MID-LEVEL HEIGHTS LEAVE NO TILT OF THE ODDS TOWARD DRIER OR WETTER
THAN NORMAL WEATHER ACROSS OAHU, KAUAI, AND NI’IHAU.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 10% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 20% OF TODAY'S GFS SUPERENSEMBLE MEAN
CENTERED ON DAY 11, 30% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY
11, AND 40% 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, WITH
FAIR AGREEMENT ON SYNOPTIC PATTERN AMONG DYNAMICAL MODELS, OFFSET BY WEAKER
ANOMALIES AND CONTRADICTORY GUIDANCE FROM FORECAST TOOLS.
FORECASTER: RICH TINKER
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
NOVEMBER 16.
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:
19861029 - 20031030 - 19861106 - 19591006 - 19651109
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:
20031101 - 19591005 - 19861028 - 19721025 - 19651108
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR NOV 01 - 05 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A B IDAHO A A NEVADA A A
W MONTANA A A E MONTANA B N WYOMING N B
UTAH A B ARIZONA N B COLORADO N B
NEW MEXICO B B N DAKOTA B B S DAKOTA B B
NEBRASKA N B KANSAS B B OKLAHOMA B B
N TEXAS B B S TEXAS B B W TEXAS B B
MINNESOTA B B IOWA B B MISSOURI B B
ARKANSAS B B LOUISIANA B B WISCONSIN B B
ILLINOIS B B MISSISSIPPI B B MICHIGAN B B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE B B ALABAMA B B NEW YORK B B
VERMONT B B NEW HAMP B B MAINE B B
MASS B B CONN B B RHODE IS B B
PENN B B NEW JERSEY B B W VIRGINIA B B
MARYLAND B B DELAWARE B B VIRGINIA B B
N CAROLINA B B S CAROLINA B B GEORGIA B B
FL PNHDL B N FL PENIN N A AK N SLOPE A B
AK ALEUTIAN A B AK WESTERN A B AK INT BSN A N
AK S INT A N AK SO COAST A N AK PNHDL A N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR NOV 03 - 09 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 A
W MONTANA A A E MONTANA N A WYOMING A A
UTAH A N ARIZONA A B COLORADO A N
NEW MEXICO A B N DAKOTA B A S DAKOTA A N
NEBRASKA A N KANSAS A N OKLAHOMA A B
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA N N IOWA A N MISSOURI A N
ARKANSAS A B LOUISIANA A B WISCONSIN N N
ILLINOIS A N MISSISSIPPI A B MICHIGAN N N
INDIANA N N OHIO N N KENTUCKY N N
TENNESSEE A N ALABAMA A N NEW YORK N N
VERMONT B N NEW HAMP B N MAINE B N
MASS B A CONN B A RHODE IS B A
PENN N N NEW JERSEY N A W VIRGINIA N N
MARYLAND N A DELAWARE N A VIRGINIA N A
N CAROLINA N A S CAROLINA N A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A N
AK ALEUTIAN A N AK WESTERN N N AK INT BSN N N
AK S INT A N AK SO COAST A N AK PNHDL A N
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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