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FXUS06 KWBC 241902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU AUGUST 24 2023
6-10 DAY OUTLOOK FOR AUG 30 - SEP 03, 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. 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 ALL BUT FAR WESTERN PORTIONS OF
ALASKA, CONSISTENT WITH CALIBRATED REFORECAST TEMPERATURES FROM THE GFS AND
ECMWF ENSEMBLE MEANS. ABOVE NORMAL TEMPERATURE CHANCES ARE ALSO ENHANCED OVER
THE SOUTHWESTERN QUADRANT OF THE LOWER 48 STATES, THE CENTRAL CONUS, AND THE
GULF COAST, SUPPORTED BY THESE SAME TOOLS. THE GEFS PREDICTS A GREATER EXTENT
OF FAVORED ABOVE NORMAL TEMPERATURES ACROSS THE WEST THAN DOES THE ECMWF
ENSEMBLE MEAN. BELOW NORMAL TEMPERATURE CHANCES ARE INCREASED ACROSS
SIGNIFICANT PORTIONS OF THE EAST, BUT THE CALIBRATED REFORECAST TEMPERATURE
TOOLS DIFFER ON THE SPATIAL EXTENT. THE GEFS DEPICTS BELOW NORMAL TEMPERATURES
OVER THE GREAT LAKES, NORTHEAST, AND THE MID-ATLANTIC REGION, WHILE THE ECMWF
EXPANDS THIS ANTICIPATED COVERAGE EVEN FARTHER TO INCLUDE PORTIONS OF THE UPPER
AND MIDDLE MISSISSIPPI VALLEY, THE OHIO AND TENNESSEE VALLEYS, MOST OF THE
APPALACHIANS, AND THE CAROLINAS. 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. 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 THE VICINITY OF WASHINGTON
STATE. 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 NORTH-CENTRAL TEXAS NORTHEASTWARD ACROSS THE MIDDLE
MISSISSIPPI VALLEY. NEAR THE EASTERN AND SOUTHERN PERIPHERY OF THE 500-HPA
TROUGH CENTERED NEAR THE EAST COAST, ABOVE NORMAL PRECIPITATION CHANCES ARE
INCREASED FOR MAINE AND PARTS OF THE SOUTHEAST. INCREASED TROPICAL ACTIVITY IN
THE GULF OF MEXICO, COINCIDENT WITH A LINGERING BAROCLINIC ZONE, ELEVATES THE
ODDS OF ABOVE NORMAL PRECIPITATION IN THE EASTERN GULF COAST REGION, ESPECIALLY
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 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
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 01 - 07 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 +90 METERS NEAR SOUTHEAST ALASKA. RELATIVELY WEAK
TROUGHS ARE DEPICTED NEAR THE WEST AND EAST COASTS OF THE CONUS, WITH A WEAK
RIDGE CENTERED OVER THE HIGH PLAINS.
ABOVE NORMAL TEMPERATURE CHANCES ARE ELEVATED FOR MUCH OF THE CONUS IN WEEK-2,
CONSISTENT WITH CALIBRATED REFORECAST TEMPERATURES FROM THE GFS AND ECMWF
ENSEMBLE MEANS. THE HIGHEST PROBABILITIES ARE LOCATED OVER TEXAS (>70%). WITH
TROUGHING EXPECTED TO WEAKEN NEAR THE EAST COAST DURING THE FORECAST PERIOD,
TEMPERATURES ARE EXPECTED TO MODERATE OVER MUCH OF THE EAST. LINGERING NEAR TO
BELOW NORMAL TEMPERATURES ARE FAVORED ACROSS THE NORTHEAST AND MID-ATLANTIC
REGION DURING WEEK-2. THE ONSHORE ADVECTION OF SHORTWAVE ENERGY ASSOCIATED WITH
THE WEST COAST TROUGH FAVORS ABOVE NORMAL TEMPERATURES OVER THE INTERIOR WEST,
DUE TO INCREASED CLOUD COVER AND PRECIPITATION. ABOVE NORMAL TEMPERATURES ARE
FAVORED OVER MOST OF ALASKA, EAST OF A 500-HPA TROUGH AXIS. AS WAS THE CASE
WITH THE EARLIER 6-10 DAY FORECAST PERIOD, BIAS-CORRECTED TEMPERATURE TOOLS
INDICATE GREATER SPATIAL COVERAGE OF BELOW NORMAL TEMPERATURE CHANCES OVER THE
EAST.
FORECAST TOOLS AND MODEL GUIDANCE CONTINUE TO INDICATE A TILT TOWARDS ABOVE
NORMAL PRECIPITATION FOR MUCH OF THE WESTERN CONUS. ANY EAST PACIFIC TROPICAL
SYSTEMS TRACKING CLOSE TO THE GULF OF CALIFORNIA COULD BRING ADDITIONAL
TROPICAL MOISTURE INTO THE SOUTHWEST. THERE IS A TILT IN THE ODDS TOWARDS BELOW
NORMAL PRECIPITATION FROM THE SOUTHERN PLAINS AND EASTERN SECTIONS OF THE
CENTRAL PLAINS EASTWARD TO INCLUDE MOST OF THE REMAINDER OF THE CONUS. HOWEVER,
THERE ARE SIGNIFICANT DIFFERENCES IN THE PRECIPITATION FORECASTS BETWEEN THE
GFS AND ECMWF ENSEMBLE MEAN CALIBRATED REFORECAST TOOLS OVER APPROXIMATELY THE
NORTHERN HALVES OF THE GREAT PLAINS AND MISSISSIPPI VALLEY. THE GEFS FAVORS
PRIMARILY BELOW NORMAL PRECIPITATION ACROSS THIS SPECIFIC REGION, WHILE THE
ECMWF FAVORS ANOMALOUS WETNESS IN THE NORTHWEST TO ANOMALOUS DRYNESS IN THE
SOUTH (OF THIS SPECIFIC REGION). THIS BROAD AREA OF FAVORED BELOW NORMAL
PRECIPITATION IS PRIMARILY DOWNSTREAM OF THE RIDGE OVER THE WEST-CENTRAL CONUS.
FOR THE SOUTHEAST, HEAVY PRECIPITATION RESULTING FROM THE INTERACTION BETWEEN
ANY TROPICAL ACTIVITY AND A WEAK BAROCLINIC ZONE IS EXPECTED TO OCCUR OVER
FLORIDA, WITH THE BULK OF THE PRECIPITATION PREDICTED TO FALL PRIOR TO THE
START OF WEEK-2. 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 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 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:
19510829 - 19790820 - 19890905 - 19610817 - 19940810
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 - 19900905 - 19890904 - 19590821 - 19720815
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 30 - SEP 03, 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 N A NEVADA A 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 B
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI N B
ARKANSAS N B LOUISIANA A B WISCONSIN N B
ILLINOIS B B MISSISSIPPI A B MICHIGAN B B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE N B ALABAMA N B NEW YORK B N
VERMONT B N NEW HAMP B N MAINE B A
MASS B N CONN B N RHODE IS B N
PENN B B NEW JERSEY B N W VIRGINIA B B
MARYLAND B B DELAWARE B B VIRGINIA B B
N CAROLINA B N S CAROLINA N N GEORGIA N A
FL PNHDL A A FL PENIN A A 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 N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 01 - 07 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 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 N 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 N B
VERMONT N B NEW HAMP N B MAINE N N
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 B S CAROLINA N B GEORGIA A B
FL PNHDL A N FL PENIN A N AK N SLOPE A A
AK ALEUTIAN N N AK WESTERN A A AK INT BSN A A
AK S INT A A AK SO COAST A A 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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