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FXUS06 KWBC 131907
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED SEPTEMBER 13 2023
6-10 DAY OUTLOOK FOR SEP 19 - 23 2023
TODAY’S MODEL SOLUTIONS ARE IN GOOD AGREEMENT REGARDING AN AMPLIFIED AND
ENERGETIC 500-HPA GEOPOTENTIAL HEIGHT PATTERN ACROSS NORTH AMERICA DURING DAYS
6 THROUGH 10. THE 0Z GFS, ECMWF, AND CANADIAN ENSEMBLE MEANS AGREE ON AN
UPSTREAM TROUGH OVER EASTERN SIBERIA THAT HELPS TO DISPLACE THE PERSISTENT
TROUGH NEAR THE WEST COAST OF ALASKA EASTWARD INTO THE INTERIOR. A STRONG
EAST-WEST ORIENTED ANOMALOUS RIDGE IS FORECAST ACROSS THE NORTH-CENTRAL PACIFIC
OCEAN. BETWEEN THE TWO MEAN TROUGHS TO THE NORTH AND THE STRONG ANOMALOUS FLAT
RIDGE TO THE SOUTH, AN ANOMALOUS WESTERLY JET IS EXPECTED TO SET UP AND EXTEND
EASTWARD ACROSS SOUTHERN ALASKA AND THE NEARBY GULF OF ALASKA. DOWNSTREAM, THE
MANUAL 500-HPA HEIGHT BLEND, A NEARLY EQUAL BLEND OF THE THREE ENSEMBLE MEAN
HEIGHT FORECASTS NOTED EARLIER, PREDICTS A TROUGH ACROSS THE INTERIOR OF
WESTERN NORTH AMERICA, ACCOMPANIED BY NEAR TO BELOW NORMAL MID-LEVEL HEIGHTS.
ANOTHER STRONG ANOMALOUS RIDGE, THOUGH THIS ONE IS ORIENTED MERIDIONALLY, IS
DEPICTED OVER EASTERN CANADA, AND MUCH OF THE NORTHEASTERN QUARTER OF THE
CONTIGUOUS U.S. (CONUS). THE MANUAL HEIGHT BLEND ALSO FORECASTS A WEAK,
LINGERING TROUGH OVER THE SOUTHEAST AND ADJACENT EASTERN GULF OF MEXICO. OUT
OVER THE SUBTROPICAL WESTERN ATLANTIC, HURRICANE LEE CONTINUES TO CHURN AS IT
TRACKS SLOWLY NORTHWESTWARD. THE LATEST TRACK PROJECTIONS (AS OF 11AM AST) FROM
THE NATIONAL HURRICANE CENTER CONTINUE TO SHOW SIGNIFICANT UNCERTAINTY, WITH
POTENTIAL LANDFALL LOCATIONS AS FAR WEST AS CAPE COD AND AS FAR EAST AS CENTRAL
NOVA SCOTIA, WITH THE BEST GUESS TRACK TAKING LEE THROUGH THE GULF OF MAINE/BAY
OF FUNDY REGION. BY THE START OF THE 6-10 DAY PERIOD, HOWEVER, LEE IS EXPECTED
TO BE NORTH OF NEWFOUNDLAND, AND THEREFORE WELL REMOVED FROM THE NORTHEAST
CONUS.
THE 6-10 DAY ERF TEMPERATURE CONSOLIDATION, WHICH IS A SKILL-WEIGHTED AVERAGE
OF GEFS AND ECMWF REFORECAST TEMPERATURES, FAVORS BELOW NORMAL TEMPERATURE
CHANCES FOR NEARLY ALL AREAS WEST OF THE CONTINENTAL DIVIDE, AND FOR
APPROXIMATELY THE SOUTHWESTERN QUARTER OF ALASKA. THIS IS GENERALLY CONSISTENT
WITH THE PROXIMITY OF MID-LEVEL TROUGHS, AND IN THE CASE OF SOUTHWESTERN
ALASKA, ANOMALOUSLY COOL SEA SURFACE TEMPERATURES. BIAS-CORRECTED TEMPERATURES
FROM THE VARIOUS ENSEMBLE MEANS SUPPORTED THE NOTION OF EXPANDING FAVORED BELOW
NORMAL TEMPERATURES ACROSS ALL OF SOUTHERN ALASKA. THE STATISTICAL ANALOG
TEMPERATURE PROBABILITIES FROM THE MANUAL HEIGHT BLEND ARE ALSO SUPPORTIVE OF
INCREASED CHANCES OF BELOW NORMAL TEMPERATURES ACROSS THE WESTERN CONUS. THE
CONSOLIDATED AND STATISTICAL ANALOG TEMPERATURE TOOLS DEPICT ABOVE NORMAL
TEMPERATURE CHANCES FOR MUCH OF THE CONUS BETWEEN THE CONTINENTAL DIVIDE AND
APPALACHIANS, THOUGH THE LATTER TOOL FAVORS NEAR NORMAL TEMPERATURES ACROSS
APPROXIMATELY THE SOUTHERN THIRD OF THIS REGION. THIS IS WHERE THE INFLUENCE OF
THE STRONG ANOMALOUS BLOCKING RIDGE TO THE NORTH TAPERS OFF, AND THE
BIAS-CORRECTED TEMPERATURE TOOLS FROM THE ENSEMBLE MEANS UNDERSCORE THIS
UNCERTAINTY WITH PREDICTIONS RANGING FROM BELOW TO NEAR TO ABOVE NORMAL
TEMPERATURES BEING FAVORED. THE TEMPERATURE CONSOLIDATION TOOL FAVORS ABOVE
NORMAL TEMPERATURES OVER NORTHEASTERN PARTS OF ALASKA, MUCH OF THE NORTHEAST
CONUS, AND FLORIDA. NEAR NORMAL TEMPERATURES WERE DEPICTED OVER A LARGE PORTION
OF THE SOUTHEAST, MID-ATLANTIC, AND SOUTHERN NEW ENGLAND, SUPPORTED BY THE
AUTO-TEMPERATURE TOOL. TODAY’S 6-10 DAY MANUAL SURFACE TEMPERATURE OUTLOOK IS
LARGELY BASED ON THE TEMPERATURE CONSOLIDATION AND AUTO-TEMPERATURE FORECASTS.
THE MID-LEVEL TROUGH AND CYCLONIC CURVATURE PREDICTED OVER ALASKA ENHANCES THE
ODDS FOR ABOVE NORMAL PRECIPITATION OVER MOST OF THE STATE. THIS IS CONSISTENT
WITH CALIBRATED -REFORECAST PRECIPITATION FROM THE 0Z GFS, ECMWF, AND CANADIAN
ENSEMBLE MEANS. THE TROUGH PREDICTED OVER THE INTERIOR OF WESTERN NORTH AMERICA
INCREASES THE CHANCES FOR ABOVE NORMAL PRECIPITATION FOR MOST OF THE INTERIOR
WESTERN AND CENTRAL CONUS, AND IS ALSO SUPPORTED BY THE CALIBRATED-REFORECAST
PRECIPITATION FORECASTS. THE EXCEPTION INCLUDES PARTS OF WASHINGTON, OREGON,
NORTHERN CALIFORNIA, AND NEVADA, WHERE NEAR TO BELOW NORMAL PRECIPITATION
CHANCES ARE FAVORED IN THE DRIER AIR BEHIND THE MID-LEVEL TROUGH. BELOW NORMAL
PRECIPITATION IS FAVORED FROM THE GREAT LAKES AND NORTHEAST SOUTHWARD AND
SOUTHWESTWARD ACROSS THE MID-ATLANTIC REGION, OHIO, TENNESSEE, AND LOWER
MISSISSIPPI VALLEYS, AND PORTIONS OF THE DEEP SOUTH, IN THE DRIER AIR
ASSOCIATED WITH A MID-LEVEL RIDGE, ANTICYCLONIC CURVATURE, AND NEAR TO ABOVE
NORMAL 500-HPA HEIGHTS. NEAR THE SOUTHEAST COAST, NEAR TO ABOVE NORMAL
PRECIPITATION CHANCES ARE FAVORED, IN PROXIMITY TO A WEAK MID-LEVEL TROUGH.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 33% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY
8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: NEAR AVERAGE, 3 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG THE 500-HPA HEIGHT FORECASTS, BUT DISAGREEMENTS AMONG THE
VARIOUS TEMPERATURE AND PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR SEP 21 - 27 2023
DURING WEEK-2, THE MANUAL 500-HPA HEIGHT BLEND (WHICH NEARLY EQUALLY WEIGHTS
THE THREE 0Z ENSEMBLE MEANS) CARVES OUT A BROAD MEAN TROUGH OVER MOST OF
WESTERN NORTH AMERICA, WITH AN ASSOCIATED NEGATIVE HEIGHT ANOMALY CENTER ALONG
THE BRITISH COLUMBIA COAST. THE STRONG, ZONAL ANOMALOUS RIDGE PREDICTED OVER
THE NORTH-CENTRAL PACIFIC DURING THE EARLIER 6-10 DAY PERIOD IS EXPECTED TO
PERSIST THROUGHOUT WEEK-2. MOST OF EASTERN NORTH AMERICA IS PREDICTED TO BE
DOMINATED BY A HIGHLY ANOMALOUS, MERIDIONAL RIDGE, WITH THE EXCEPTION OF THE
SOUTHEAST CONUS WHERE A WEAK TROUGH IS ANTICIPATED.
THE TEMPERATURE PATTERN FORECAST FOR THE WEEK 2 PERIOD IS GENERALLY SIMILAR TO
THE 6-10 DAY TEMPERATURE OUTLOOK. THERE ARE ENHANCED ODDS OF BELOW NORMAL
TEMPERATURES OVER PRACTICALLY ALL AREAS WEST OF THE CONTINENTAL DIVIDE,
CONSISTENT WITH THE WEEK-2 STATISTICAL ANALOG TEMPERATURE PROBABILITIES AND THE
TEMPERATURE CONSOLIDATION. THE LATTER TOOL ALSO DEPICTS BELOW NORMAL
TEMPERATURES OVER APPROXIMATELY THE SOUTHERN HALF OF ALASKA, LARGELY DUE TO
ANOMALOUS NORTHERLY FLOW. FOR NEARLY ALL AREAS EAST OF THE CONTINENTAL DIVIDE,
THERE ARE INCREASED CHANCES FOR ABOVE NORMAL TEMPERATURES, PRIMARILY ASSOCIATED
WITH A MID-LEVEL RIDGE AND NEAR TO ABOVE NORMAL 500-HPA HEIGHTS. THERE ARE
SLIGHTLY TILTED ODDS FOR WARMER-THAN-NORMAL MEAN TEMPERATURES OVER PARTS OF
NORTHEASTERN ALASKA.
THE MID-LEVEL TROUGH PREDICTED NEAR THE WEST COAST FAVORS SLIGHTLY INCREASED
ODDS FOR ABOVE NORMAL PRECIPITATION ACROSS MUCH OF THE WESTERN AND CENTRAL
CONUS. CHANCES FOR ABOVE NORMAL PRECIPITATION EXCEED 40% FOR WESTERN PARTS OF
WASHINGTON, OREGON, AND FAR NORTHERN CALIFORNIA, WHERE THE PREVAILING WIND
DIRECTION IS EXPECTED TO BE PERPENDICULAR TO THE CASCADE MOUNTAIN RANGE. ODDS
FAVORING ABOVE NORMAL PRECIPITATION ALSO EXCEED 40% FOR A LARGE FRACTION OF THE
GREAT PLAINS AND MISSISSIPPI VALLEY, WHERE AN INCREASE IN LOW-LEVEL GULF
MOISTURE HAS A BETTER CHANCE OF INTERACTING WITH ANY FRONTAL SYSTEMS. EASTERLY
FLOW ANTICIPATED ACROSS NORTHERN FLORIDA ALSO SUPPORTS INCREASED ODDS OF ABOVE
NORMAL PRECIPITATION. BELOW NORMAL PRECIPITATION CHANCES ARE ELEVATED OVER
PORTIONS OF THE LOWER GREAT LAKES REGION AND NORTHEAST, ATTRIBUTED TO THE
PROXIMITY OF THE STRONG MID-LEVEL RIDGE AND POSITIVE 500-HPA HEIGHT ANOMALIES.
IN ALASKA, ABOVE NORMAL PRECIPITATION PROBABILITIES ARE INCREASED DUE TO THE
PROXIMITY OF MID-LEVEL TROUGHS, THOUGH NOT AS MUCH PRECIPITATION IS EXPECTED
ACROSS SOUTHEAST ALASKA AS DURING THE EARLIER 6-10 DAY PERIOD. THIS IS
ASSOCIATED WITH ANOMALOUS EASTERLY (OFFSHORE) FLOW DEVELOPING ON THE NORTH SIDE
OF THE NEGATIVE 500-HPA HEIGHT ANOMALY ALONG THE BRITISH COLUMBIA COAST AND
ACCOMPANYING MID-LEVEL TROUGH.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 33% 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
REASONABLY GOOD AGREEMENT AMONG MODEL ENSEMBLES ON THE PERSISTENT SYNOPTIC
PATTERN, OFFSET BY SOME DIFFERENCES AMONG THE TEMPERATURE AND PRECIPITATION
TOOLS.
FORECASTER: ANTHONY A
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:
20010923 - 20090911 - 20060908 - 19620925 - 19870921
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:
20010923 - 20090823 - 19620924 - 20060906 - 20090914
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 19 - 23 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B N OREGON B N NRN CALIF B N
SRN CALIF B N IDAHO B A NEVADA B A
W MONTANA B A E MONTANA N A WYOMING B A
UTAH B A ARIZONA B N COLORADO N 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 N W TEXAS A A
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A N LOUISIANA A N WISCONSIN A A
ILLINOIS A N MISSISSIPPI A B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE N B ALABAMA A B 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 N B NEW JERSEY N B W VIRGINIA N B
MARYLAND N B DELAWARE N B VIRGINIA N B
N CAROLINA N N S CAROLINA N N GEORGIA N N
FL PNHDL N N FL PENIN A N AK N SLOPE N A
AK ALEUTIAN N N AK WESTERN B A AK INT BSN N A
AK S INT B A AK SO COAST B A AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 21 - 27 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B A
SRN CALIF B N IDAHO B A NEVADA B A
W MONTANA B A E MONTANA A A WYOMING N A
UTAH B N ARIZONA B N COLORADO N N
NEW MEXICO A N 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 A LOUISIANA A A WISCONSIN A A
ILLINOIS A N MISSISSIPPI A N MICHIGAN A N
INDIANA A N OHIO A B KENTUCKY A N
TENNESSEE A N ALABAMA A N NEW YORK A B
VERMONT A B NEW HAMP A B MAINE A B
MASS A N CONN A N RHODE IS A N
PENN A B NEW JERSEY A N W VIRGINIA A B
MARYLAND A N DELAWARE A N 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 N
AK ALEUTIAN B N AK WESTERN B A AK INT BSN N A
AK S INT B N AK SO COAST B N AK PNHDL B 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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