047
FXUS06 KWBC 231902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED AUGUST 23 2023
6-10 DAY OUTLOOK FOR AUG 29 - SEP 02, 2023
THE 6-10 DAY MEAN 500-HPA HEIGHT FORECASTS FROM THE LATEST ECMWF, GFS, AND
CANADIAN ENSEMBLE MEANS ARE IN EXCELLENT AGREEMENT TODAY OVER THE FORECAST
DOMAIN. MID-LEVEL TROUGHS ARE PREDICTED OVER THE BERING SEA/ALEUTIANS, ALONG
THE WEST COAST OF THE CONTIGUOUS UNITED STATES (CONUS), AND OVER THE EASTERN
CONUS. THE TROUGH EXPECTED OVER THE BERING SEA AND ALEUTIANS IS BY FAR THE MOST
ANOMALOUS OF THE THREE TROUGHS, WITH THE LARGEST 500-HPA HEIGHT DEPARTURES IN
EXCESS OF -120 METERS. MID-LEVEL RIDGES ARE FORECAST FROM THE FAR EASTERN
PACIFIC NORTHEASTWARD ACROSS EASTERN ALASKA, WESTERN AND CENTRAL CANADA, AND
OVER THE WEST-CENTRAL CONUS. MAXIMUM HEIGHT DEPARTURES EXCEED +90 METERS OVER
SOUTHEAST ALASKA AND MUCH OF WESTERN CANADA.
ABOVE NORMAL TEMPERATURES ARE FAVORED OVER THE EASTERN HALF OF MAINLAND ALASKA
AND ALL OF SOUTHEAST ALASKA, CONSISTENT WITH CALIBRATED REFORECAST TEMPERATURES
FROM THE VARIOUS ENSEMBLE MEANS. ABOVE NORMAL TEMPERATURE CHANCES ARE ALSO
ENHANCED OVER MOST OF THE WESTERN AND CENTRAL CONUS, AND NEAR THE GULF AND
SOUTHEAST COASTS,SUPPORTED BY THE CALIBRATED REFORECAST TEMPERATURES FROM THE
ECMWF AND GFS ENSEMBLE MEANS, AND 2-METER CALIBRATED TEMPERATURES FROM THE 0Z
ECMWF ENSEMBLE MEAN. THE SHORT-TERM BIAS-CORRECTED NAEFS TEMPERATURE FORECAST
ALSO DEPICTS ABOVE NORMAL TEMPERATURES OVER MUCH OF THE INTERIOR WEST, CENTRAL,
AND PORTIONS OF THE SOUTHERN CONUS. MAXIMUM PROBABILITIES FAVORING ABOVE NORMAL
TEMPERATURES EXCEED 60% IN EASTERN MONTANA, THE FOUR CORNERS REGION, AND NEAR
THE GULF COAST. BELOW NORMAL TEMPERATURE CHANCES ARE INCREASED OVER MUCH OF THE
NORTHEAST, MID-ATLANTIC, GREAT LAKES, AND OHIO VALLEY, CONSISTENT WITH
CALIBRATED REFORECAST TEMPERATURES FROM THE ECMWF ENSEMBLE MEAN. CALIBRATED
REFORECAST TEMPERATURES FROM THE GEFS DEPICT NEAR NORMAL TEMPERATURES OVER THE
NORTHEAST, WITH ONLY A HINT OF BELOW NORMAL TEMPERATURES FAVORED OVER CAPE COD;
WHILE THOSE FROM THE CANADIAN ENSEMBLE MEAN DEPICT MUCH GREATER SPATIAL
COVERAGE OF BELOW NORMAL TEMPERATURES, INCLUDING NEARLY ALL OF THE EASTERN HALF
OF THE CONUS. BIAS-CORRECTED TEMPERATURES FROM THE ENSEMBLE MEANS GENERALLY
PREDICT INCREASED SPATIAL COVERAGE OF BELOW NORMAL TEMPERATURES OVER THE EAST,
BUT GIVEN THE ANTICIPATED MID-LEVEL HEIGHT ANOMALY PATTERN, THESE SCENARIOS
SEEM LESS LIKELY. BELOW NORMAL TEMPERATURES ARE ALSO FAVORED OVER SOUTHWESTERN
ALASKA, IN PROXIMITY TO AN ANOMALOUSLY DEEP MID-LEVEL TROUGH.
THE DEPICTED MID-LEVEL TROUGH ALONG THE WEST COAST OF THE CONUS AND CONTINUED
AVAILABLE SUBTROPICAL MOISTURE FROM THE GULF OF CALIFORNIA TILTS ODDS TOWARDS
ABOVE NORMAL PRECIPITATION FOR MUCH OF THE WESTERN CONUS. MAXIMUM PROBABILITIES
FOR ABOVE NORMAL PRECIPITATION EXCEED 50% OVER WASHINGTON STATE AND NORTHERN
OREGON. DOWNSTREAM OF THE RIDGE AXIS CENTERED OVER THE GREAT PLAINS, A BROAD
AREA OF BELOW NORMAL PRECIPITATION IS FAVORED FOR MOST OF THE PLAINS AND
MISSISSIPPI VALLEY, WESTERN AND CENTRAL GREAT LAKES REGION, AND MUCH OF THE
OHIO AND TENNESSEE VALLEYS, WITH THE GREATEST PROBABILITIES FAVORING BELOW
NORMAL PRECIPITATION IN EXCESS OF 50% OVER CENTRAL PORTIONS OF THE MISSISSIPPI
VALLEY AND ADJACENT PLAINS. AHEAD OF THE MID-LEVEL TROUGH CENTERED NEAR THE
APPALACHIANS, ABOVE NORMAL PRECIPITATION CHANCES ARE INCREASED. IN THE
SOUTHEAST, A STALLED FRONT MAY INTERACT WITH SUBTROPICAL MOISTURE FROM THE GULF
OF MEXICO. TROUGHING OVER THE BERING SEA FAVORS WIDESPREAD ONSHORE FLOW AND
ABOVE NORMAL PRECIPITATION FOR MOST OF ALASKA. THE EXCEPTION IS CENTRAL AND
SOUTHERN PARTS OF SOUTHEAST ALASKA, WHERE NEAR TO BELOW NORMAL PRECIPITATION IS
MOST LIKELY BASED ON THE PROXIMITY OF A MODERATELY STRONG MID-LEVEL RIDGE.
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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
EXCELLENT AGREEMENT IN THE 500-HPA HEIGHT FIELDS, AND GOOD AGREEMENT IN THE
SURFACE TEMPERATURE AND PRECIPITATION PATTERNS.
8-14 DAY OUTLOOK FOR AUG 31 - SEP 06, 2023
AN OVERALL DE-AMPLIFICATION OF THE NORTH AMERICAN MID-LEVEL CIRCULATION PATTERN
IS EXPECTED DURING WEEK-2. A TROUGH OVER FAR EASTERN SIBERIA IS FORECAST TO
APPROACH THE BERING SEA TROUGH, CARVING OUT ONE BROAD MEAN TROUGH ACROSS THE
REGION, WITH MUCH SMALLER 500-HPA HEIGHT DEPARTURES ANTICIPATED COMPARED TO THE
EARLIER 6-10 DAY PERIOD. MID-LEVEL RIDGING IS PREDICTED FROM THE EASTERN
PACIFIC NORTHEASTWARD ACROSS SOUTHEAST ALASKA AND WESTERN CANADA, WITH MAXIMUM
HEIGHT ANOMALIES EXCEEDING +60 METERS OVER SOUTHEAST ALASKA. RELATIVELY WEAK
TROUGHS ARE DEPICTED NEAR THE WEST AND EAST COASTS OF THE CONUS, WITH A
FLATTENED RIDGE CENTERED OVER THE GREAT PLAINS.
ABOVE NORMAL TEMPERATURE CHANCES ARE ELEVATED FOR MUCH OF THE CONUS IN WEEK-2.
THE HIGHEST PROBABILITIES ARE LOCATED OVER THE SOUTH-CENTRAL CONUS (>60%). WITH
TROUGHING EXPECTED TO WEAKEN NEAR THE EAST COAST DURING THE FORECAST PERIOD,
TEMPERATURES ARE FAVORED TO MODERATE OVER MUCH OF THE EAST. THIS IS CONSISTENT
WITH CALIBRATED REFORECAST TEMPERATURE GUIDANCE FROM THE ENSEMBLE MEANS. THE
ONSHORE ADVECTION OF SHORTWAVE ENERGY ASSOCIATED WITH THE WEST COAST TROUGH
FAVORS NEAR NORMAL TEMPERATURES OVER THE INTERIOR WEST, DUE TO INCREASED CLOUD
COVER AND PRECIPITATION. TEMPERATURES ACROSS THE NORTHEAST ARE EXPECTED TO
MODERATE FROM BELOW NORMAL DURING THE 6-10 DAY PERIOD TO NEAR NORMAL DURING
WEEK-2. ABOVE NORMAL TEMPERATURES ARE FAVORED OVER MOST OF ALASKA, EAST OF A
500-HPA TROUGH AXIS.
FORECAST TOOLS AND MODEL GUIDANCE CONTINUE TO INDICATE A TILT TOWARDS ABOVE
NORMAL PRECIPITATION FOR MUCH OF THE WESTERN CONUS, WITH HIGHER ODDS (>40%)
CENTERED OVER THE VICINITY OF THE NORTHERN INTERMOUNTAIN REGION AND IN A STRIPE
FROM FAR SOUTHERN CALIFORNIA NORTHEASTWARD ACROSS UTAH AND PARTS OF ADJACENT
STATES. THERE IS A TILT IN THE ODDS TOWARDS BELOW NORMAL PRECIPITATION FOR A
LARGE FRACTION OF THE GREAT PLAINS, MOST OF THE MISSISSIPPI VALLEY, GREAT LAKES
REGION, OHIO AND TENNESSEE VALLEYS, APPALACHIANS, AND CONTINUING EASTWARD TO
THE MID-ATLANTIC AND NORTHEAST COASTS. THIS BROAD AREA OF FAVORED BELOW NORMAL
PRECIPITATION IS PRIMARILY DOWNSTREAM OF THE RIDGE OVER THE WEST-CENTRAL CONUS.
INCREASED TROPICAL ACTIVITY IN THE GULF OF MEXICO, COINCIDENT WITH A LINGERING
BAROCLINIC ZONE, ELEVATES THE ODDS OF ABOVE NORMAL PRECIPITATION FOR THE GULF
COAST REGION, ESPECIALLY FLORIDA. PERSISTENT TROUGHING OVER THE BERING SEA
FAVORS ABOVE NORMAL PRECIPITATION FOR MOST OF ALASKA, WITH A SLIGHT TILT IN THE
ODDS TOWARDS BELOW NORMAL PRECIPITATION OVER SOUTHERN PORTIONS OF SOUTHEAST
ALASKA.
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: NEAR AVERAGE, 3 OUT OF 5, DUE TO
GOOD OVERALL AGREEMENT AMONG THE ENSEMBLE MODEL HEIGHT FORECASTS AND THE
SURFACE TEMPERATURE TOOLS, BUT OFFSET BY SIGNIFICANT UNCERTAINTY REGARDING THE
EVOLUTION OF ANY TROPICAL SYSTEMS THAT COULD DEVELOP OVER THE GULF OF MEXICO IN
WEEK-2.
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:
19590822 - 19900903 - 19850906 - 19510829 - 19850831
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:
19900903 - 19590821 - 20000902 - 19850905 - 19830827
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 29 - SEP 02, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON N A NRN CALIF A A
SRN CALIF A A IDAHO A A NEVADA A A
W MONTANA A A E MONTANA A N WYOMING A A
UTAH A A ARIZONA A A COLORADO A N
NEW MEXICO A N N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A N W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI N B
ARKANSAS N B LOUISIANA A N WISCONSIN A B
ILLINOIS B B MISSISSIPPI A N MICHIGAN B B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE N B ALABAMA A A NEW YORK B A
VERMONT B A NEW HAMP B A MAINE N A
MASS B A CONN B A RHODE IS B A
PENN B A NEW JERSEY B A W VIRGINIA B N
MARYLAND B A DELAWARE B A VIRGINIA B A
N CAROLINA N A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE N A
AK ALEUTIAN N A AK WESTERN N A AK INT BSN A A
AK S INT A A AK SO COAST A A AK PNHDL A N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 31 - SEP 06, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF N A IDAHO N A NEVADA N A
W MONTANA N A E MONTANA A A WYOMING A A
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A N N DAKOTA A N S DAKOTA A N
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A N W TEXAS A B
MINNESOTA A N IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA A A WISCONSIN A B
ILLINOIS A B MISSISSIPPI A B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A N NEW YORK N B
VERMONT N N NEW HAMP N N MAINE N N
MASS N N CONN N N RHODE IS N N
PENN A B NEW JERSEY N B W VIRGINIA A B
MARYLAND A B DELAWARE A B VIRGINIA A B
N CAROLINA A B S CAROLINA A N GEORGIA A N
FL PNHDL A A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN N A AK WESTERN N A AK INT BSN A A
AK S INT A A AK SO COAST A A 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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