908
FXUS06 KWBC 251902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI AUGUST 25 2023
6-10 DAY OUTLOOK FOR AUG 31 - SEP 04, 2023
THE 6-10 DAY MEAN 500-HPA HEIGHT FORECASTS FROM THE LATEST ECMWF, GFS, AND
CANADIAN ENSEMBLE MEANS ARE IN VERY GOOD AGREEMENT TODAY OVER THE FORECAST
DOMAIN. THE MANUAL 500-HPA HEIGHT BLEND, WHICH NEARLY EQUALLY WEIGHTS THE 0Z
RUNS OF THE THREE ENSEMBLE MEANS DEPICTS MID-LEVEL TROUGHS OVER THE BERING
SEA/ALEUTIANS, ALONG THE WEST COAST OF THE CONTIGUOUS UNITED STATES (CONUS),
AND NEAR THE EAST COAST. THE ECMWF ENSEMBLE MEAN DEPICTS THE MEAN TROUGH AXIS
JUST OFF THE EAST COAST, WHILE THE GFS AND CANADIAN ENSEMBLE MEANS FORECAST THE
AXIS EITHER ON THE COAST OR JUST INLAND. THE TROUGH EXPECTED OVER THE BERING
SEA AND ALEUTIANS IS FORECAST TO WEAKEN RAPIDLY, AS ANOTHER TROUGH DEVELOPS
JUST UPSTREAM OVER EASTERN SIBERIA, ACCOMPANIED BY SIGNIFICANT 500-HPA HEIGHT
FALLS (>-90 METERS). MID-LEVEL RIDGES ARE FORECAST FROM THE FAR EASTERN PACIFIC
NORTHEASTWARD ACROSS EASTERN ALASKA AND WESTERN CANADA, AND OVER THE
WEST-CENTRAL CONUS. MAXIMUM HEIGHT DEPARTURES EXCEED +120 METERS OVER THE GULF
OF ALASKA.
ABOVE NORMAL TEMPERATURES ARE FAVORED OVER MOST OF ALASKA (EXCEPT FOR
SOUTHWESTERN ALASKA WHERE NEAR NORMAL TEMPERATURES ARE FAVORED), CONSISTENT
WITH CALIBRATED REFORECAST TEMPERATURES FROM THE GFS AND ECMWF ENSEMBLE MEANS.
ABOVE NORMAL TEMPERATURE CHANCES ARE ALSO ENHANCED OVER THE WESTERN, CENTRAL,
AND SOUTHEASTERN CONUS, SUPPORTED BY THESE SAME TOOLS. A SWATH OF 70% OR
GREATER PROBABILITIES FAVORING ABOVE NORMAL TEMPERATURES IS INDICATED OVER THE
GREAT PLAINS. BELOW NORMAL TEMPERATURE CHANCES ARE INCREASED ACROSS THE
MID-ATLANTIC REGION, MOST OF THE NORTHEAST AND APPALACHIANS, AND UPPER OHIO
VALLEY. BIASED-CORRECTED TEMPERATURES FROM THE GFS AND ECMWF ENSEMBLE MEANS
DEPICT GREATER SPATIAL COVERAGE OF FAVORED BELOW NORMAL TEMPERATURES COMPARED
TO THEIR REFORECAST COUNTERPARTS. THE SHORT-TERM BIAS-CORRECTED NAEFS
TEMPERATURE FORECAST DEPICTS BELOW NORMAL TEMPERATURES FOR MOST AREAS EAST OF
THE MISSISSIPPI RIVER. PREDICTING THE EXTENT OF FAVORED BELOW NORMAL
TEMPERATURES IS THE MOST CHALLENGING ASPECT OF TODAY’S 6-10 DAY TEMPERATURE
OUTLOOK.
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. DOWNSTREAM OF THE
RIDGE AXIS CENTERED OVER THE HIGH PLAINS A BROAD AREA OF BELOW NORMAL
PRECIPITATION IS FAVORED, WHICH INCLUDES MUCH OF THE LOWER 48 STATES EAST OF
THE ROCKIES. THIS IS CONSISTENT WITH THE CONSOLIDATED PRECIPITATION TOOL.
MAXIMUM PROBABILITIES FAVORING BELOW NORMAL PRECIPITATION ARE IN EXCESS OF 50%
FROM TEXAS AND OKLAHOMA NORTHEASTWARD TO THE LOWER OHIO VALLEY. NEAR THE
SOUTHERN PERIPHERY OF THE EAST COAST MID-LEVEL TROUGH INCREASED TROPICAL
ACTIVITY IN THE GULF OF MEXICO AND A LINGERING BAROCLINIC ZONE ELEVATE THE ODDS
OF ABOVE NORMAL PRECIPITATION IN FLORIDA. TROUGHING OVER THE BERING SEA FAVORS
WIDESPREAD ONSHORE FLOW AND ABOVE NORMAL PRECIPITATION FOR MOST OF ALASKA. THE
EXCEPTION INCLUDES PORTIONS 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 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 30% 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
VERY GOOD AGREEMENT IN THE PREDICTED 500-HPA HEIGHT FIELDS, AND GOOD AGREEMENT
IN THE SURFACE TEMPERATURE AND PRECIPITATION PATTERNS.
8-14 DAY OUTLOOK FOR SEP 02 - 08 2023
A NOTICEABLE FLATTENING OF THE NORTH AMERICAN MID-LEVEL FLOW PATTERN IS
EXPECTED DURING WEEK-2. THE MANUAL 500-HPA HEIGHT BLEND (WHICH AGAIN IS
COMPRISED OF NEARLY EQUAL WEIGHTS AMONG THE 0Z SOLUTIONS OF THE THREE ENSEMBLE
MEANS) DEPICTS A BROAD MEAN TROUGH OVER EASTERN SIBERIA, THE BERING SEA, AND
ALEUTIANS IN THE PROCESS OF CONSOLIDATING. A MODERATELY STRONG MID-LEVEL RIDGE
IS DEPICTED OVER THE GULF OF ALASKA, MUCH OF ALASKA, AND WESTERN CANADA, WITH
MAXIMUM HEIGHT DEPARTURES IN EXCESS OF +90 METERS OVER THE EASTERN GULF OF
ALASKA. A MID-LEVEL RIDGE IS ALSO ANTICIPATED OVER THE WEST-CENTRAL CONUS, WITH
WEAK MEAN TROUGHS NEAR BOTH COASTS OF THE LOWER 48 STATES. IN THE FULL HEIGHT
FIELDS AT 500-HPA, THE MAXIMUM PREDICTED HEIGHTS (ABOUT 594 DM) ARE DEPICTED
CLOSE TO THE INTERNATIONAL BORDER BETWEEN THE SOUTHWEST CONUS AND MEXICO. WITH
THE ASSOCIATED RIDGE AXIS THIS FAR SOUTH, CONDITIONS ARE NOT FAVORABLE FOR AN
ACTIVE MONSOON ACROSS THE SOUTHWEST.
ABOVE NORMAL TEMPERATURE CHANCES ARE ELEVATED FOR MOST OF THE CONUS IN WEEK-2,
CONSISTENT WITH CALIBRATED REFORECAST TEMPERATURES FROM THE GFS, CANADIAN, AND
ECMWF ENSEMBLE MEANS. THE HIGHEST PROBABILITIES ARE LOCATED OVER THE
SOUTH-CENTRAL CONUS (>70%). WITH TROUGHING EXPECTED TO WEAKEN NEAR THE EAST
COAST DURING THE FORECAST PERIOD, TEMPERATURES ARE EXPECTED TO MODERATE OVER
THAT REGION. BIAS-CORRECTED TEMPERATURE TOOLS CONTINUE TO MAINTAIN A
SIGNIFICANT AMOUNT OF FAVORED BELOW NORMAL TEMPERATURES OVER PORTIONS OF THE
EAST. 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, IN ADVANCE OF THE WEST
COAST TROUGH. ANY EAST PACIFIC TROPICAL SYSTEMS TRACKING CLOSE TO THE GULF OF
CALIFORNIA COULD BRING ADDITIONAL TROPICAL MOISTURE INTO THE SOUTHWEST. IN
CONTRAST, CALIBRATED REFORECAST PRECIPITATION GUIDANCE FROM THE ECMWF ENSEMBLE
DEPICTS FAVORED BELOW NORMAL PRECIPITATION ACROSS MOST OF NEW MEXICO AND
SOUTHERN ARIZONA. RAW PRECIPITATION PROBABILITIES FROM THE ENSEMBLE MEANS FAVOR
EXTENSIVE ANOMALOUS DRYNESS OVER THE SOUTHWEST. THERE IS A TILT IN THE ODDS
TOWARDS BELOW NORMAL PRECIPITATION FOR MOST AREAS EAST OF THE ROCKIES,
DOWNSTREAM OF A MID-LEVEL RIDGE AXIS OVER THE WEST-CENTRAL CONUS. 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
PORTIONS OF SOUTHEAST ALASKA.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 33% OF YESTERDAY'S 0Z
GFS ENSEMBLE MEAN CENTERED ON DAY 10, 34% OF YESTERDAY'S 0Z EUROPEAN ENSEMBLE
MEAN CENTERED ON DAY 10, AND 33% OF YESTERDAY'S 0Z CANADIAN ENSEMBLE MEAN
CENTERED ON DAY 10
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 DIFFERENCES AMONG THE VARIOUS
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:
19610817 - 19790820 - 19890905 - 19940809 - 19570825
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:
19790820 - 19570825 - 19890905 - 19610817 - 19540820
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 31 - SEP 04, 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 A A NEVADA A A
W MONTANA A A E MONTANA A N WYOMING A A
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A N N DAKOTA A N S DAKOTA A B
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA A N IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA A B WISCONSIN A B
ILLINOIS A B MISSISSIPPI A B MICHIGAN A B
INDIANA N B OHIO B B KENTUCKY N B
TENNESSEE N B ALABAMA A B NEW YORK B B
VERMONT B B NEW HAMP B B MAINE N N
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 N B
FL PNHDL A N FL PENIN A N AK N SLOPE A A
AK ALEUTIAN N N AK WESTERN N A AK INT BSN A A
AK S INT A A AK SO COAST A A AK PNHDL A B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 02 - 08 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF N N IDAHO A A NEVADA A A
W MONTANA A A E MONTANA A A WYOMING A N
UTAH A N ARIZONA A B COLORADO A N
NEW MEXICO A B N DAKOTA A N S DAKOTA A N
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA A N IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA A B WISCONSIN A N
ILLINOIS A B MISSISSIPPI A B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE A B ALABAMA A B NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS A N
PENN A B NEW JERSEY A N W VIRGINIA A B
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 N AK N SLOPE A A
AK ALEUTIAN N N AK WESTERN N A AK INT BSN A A
AK S INT N A AK SO COAST N N AK PNHDL A 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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