057
FXUS06 KWBC 211903
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT MON AUGUST 21 2023
6-10 DAY OUTLOOK FOR AUG 27 - 31 2023
THE 6-10 DAY 500-HPA HEIGHT ANOMALIES AS DEPICTED BY TODAY’S WEIGHTED BLEND OF
THE ECMWF, GEFS, AND CANADIAN ENSEMBLE MEANS FEATURE POSITIVE HEIGHT ANOMALIES
FOR MUCH OF WESTERN NORTH AMERICA, WITH THE LARGEST DEPARTURES OVER SOUTHEAST
ALASKA, AS WELL AS ANOMALOUS RIDGING OVER THE NORTH ATLANTIC. BROAD WEAK
TROUGHING IS FAVORED OVER THE EASTERN CONTIGUOUS U.S. (CONUS), WITH SHORTWAVE
TROUGH SITUATED OFF THE COAST OF THE PACIFIC NORTHWEST. THIS PATTERN RESULTS IN
ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE WESTERN AND SOUTHERN CONUS AND
BELOW-NORMAL TEMPERATURES FOR THE NORTHEAST U.S. TROUGHING OFF THE WEST COAST
TILTS THE ODDS TOWARDS ABOVE-NORMAL PRECIPITATION FOR MUCH OF THE WESTERN
CONUS, WHILE THE GREAT PLAINS, MISSISSIPPI AND OHIO VALLEYS ARE FAVORED FOR
BELOW-NORMAL PRECIPITATION DOWNSTREAM OF THE RIDGE AXIS OVER WESTERN NORTH
AMERICA.
ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE WESTERN AND SOUTHERN
CONUS WITH CONTINUED RIDGING OVER THE WEST. PROBABILITIES ARE GREATEST FOR
PORTIONS OF TEXAS AND LOUISIANA, AS WELL AS MUCH OF THE INTERMOUNTAIN WEST (AT
LEAST 60%, OVER 70% FOR WESTERN AND CENTRAL MONTANA AND NORTHERN IDAHO).
MEANWHILE, NEGATIVE HEIGHT ANOMALIES OVER MUCH OF THE EASTERN U.S. RESULTS IN
ENHANCED CHANCES FOR BELOW-NORMAL TEMPERATURES, WITH HIGHEST PROBABILITIES
CENTERED OVER PENNSYLVANIA (OVER 60% CHANCE). FOR ALASKA, STRONG POSITIVE
HEIGHT ANOMALIES FAVOR ABOVE-NORMAL TEMPERATURES FOR SOUTHEASTERN ALASKA AND
MUCH OF THE CENTRAL AND EASTERN MAINLAND, WHILE TROUGHING OVER THE BERING SEA
RESULT IN A TILT TOWARDS BELOW-NORMAL TEMPERATURES ALONG THE WESTERN COAST OF
ALASKA.
THE DEPICTED SHORTWAVE TROUGH OFF THE PACIFIC NORTHWEST COAST AND CONTINUED
AVAILABLE TROPICAL MOISTURE FROM THE GULF OF CALIFORNIA TILTS ODDS TOWARDS
ABOVE-NORMAL PRECIPITATION FOR MUCH OF THE WESTERN CONUS, ESPECIALLY FOR
WASHINGTON STATE AND NORTHERN OREGON, EXCEPT FOR CENTRAL AND NORTHERN
CALIFORNIA AND ADJACENT NEVADA WHERE NEAR-NORMAL PRECIPITATION IS FAVORED.
DOWNSTREAM OF THE RIDGE AXIS, A BROAD AREA OF BELOW-NORMAL PRECIPITATION IS
MOST LIKELY FOR A SWATH FROM THE TEXAS COAST NORTH THROUGH MUCH OF THE GREAT
PLAINS, AS WELL AS THE MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, WITH HIGHEST
PROBABILITIES OVER ILLINOIS AND INDIANA (>50%). A STALLED FRONTAL BOUNDARY AND
AVAILABLE TROPICAL MOISTURE RESULTS IN A TILT TOWARDS ABOVE-NORMAL
PRECIPITATION FOR MUCH OF THE EAST COAST EAST OF THE APPALACHIANS FROM CENTRAL
FLORIDA ALL THE WAY UP TO MAINE. TROUGHING OVER THE BERING SEA FAVORS
ABOVE-NORMAL PRECIPITATION FOR THE ALASKAN MAINLAND, WHILE RIDGING OVER WESTERN
CANADA RESULTS IN A TILT TOWARDS BELOW-NORMAL PRECIPITATION FOR SOUTHEASTERN
ALASKA.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 34% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 33% 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: ABOUT AVERAGE, 3 OUT OF 5, WITH
GOOD AGREEMENT AMONG FORECAST TOOLS, OFFSET BY NOTABLE DIFFERENCES IN 500-HPA
ANOMALY SOLUTIONS AMONG MODEL ENSEMBLES.
8-14 DAY OUTLOOK FOR AUG 29 - SEP 04, 2023
MODEL SOLUTIONS FOR 500-HPA HEIGHT ANOMALIES AT THE 8-14 DAY TIME PERIOD ARE
SIMILAR TO THE EARLIER FORECAST PERIOD, ALTHOUGH THE TROUGHING FEATURES OFF
BOTH COASTS OF THE CONUS ARE SUBSTANTIALLY WEAKENED IN THE LATER PERIOD. WITH
LITTLE CHANGE IN THE SYNOPTIC PATTERN, THE TEMPERATURE AND PRECIPITATION
OUTLOOKS BEAR A CLOSE RESEMBLANCE TO THE 6-10 DAY PERIOD.
ABOVE-NORMAL TEMPERATURES CONTINUE TO BE FAVORED FOR MOST OF THE WESTERN AND
SOUTHERN CONUS. THE HIGHEST PROBABILITIES ARE CENTERED OVER TEXAS AND LOUISIANA
(>60%), AND THE CONSENSUS AMONG THE FORECAST TOOLS ONCE AGAIN FAVORS
NEAR-NORMAL TEMPERATURES ALONG THE CALIFORNIA COAST. THE NORTHEAST CONUS STILL
TILTS TOWARDS BELOW-NORMAL TEMPERATURES, ALTHOUGH WITH A MUCH-WEAKENED TROUGH
THE PROBABILITIES ARE SUBSTANTIALLY REDUCED, ONLY EXCEEDING 40% OVER SOUTHERN
NEW ENGLAND. CONTINUED RIDGING OVER WESTERN CANADA RESULTS IN ENHANCED
PROBABILITIES OF ABOVE-NORMAL TEMPERATURES FOR MOST OF ALASKA, WITH THE
EXCEPTION OF THE WESTERNMOST COAST WHERE NEAR-NORMAL TEMPERATURES ARE MOST
LIKELY.
FORECAST TOOLS AND MODEL GUIDANCE CONTINUE TO INDICATE A TILT TOWARDS
ABOVE-NORMAL PRECIPITATION FOR MUCH OF THE WESTERN CONUS WITH THE HIGHEST ODDS
(>50%) ONCE AGAIN CENTERED OVER WASHINGTON. BELOW-NORMAL PRECIPITATION IS
WEAKLY FAVORED FOR MOST OF THE CENTRAL AND EASTERN CONUS, WITH THE EXCEPTIONS
OF NEAR THE EAST AND GULF COASTS, WHERE CONTINUED TROPICAL MOISTURE RESULTS IN
NEAR-NORMAL PRECIPITATION. CONTINUED TROUGHING OVER THE BERING SEA FAVORS
ABOVE-NORMAL PRECIPITATION FOR THE ALASKAN MAINLAND, WHILE RIDGING OVER WESTERN
CANADA RESULTS IN A TILT TOWARDS BELOW-NORMAL PRECIPITATION FOR SOUTHEASTERN
ALASKA.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 34% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 33% 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: ABOUT AVERAGE, 3 OUT OF 5, DUE TO
FAIR AGREEMENT AMONG MODEL ENSEMBLES ON THE PERSISTENT SYNOPTIC PATTERN, OFFSET
BY WEAKER ANOMALIES REDUCING FORECAST CONFIDENCE.
FORECASTER: DANIEL BARANDIARAN
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:
19850902 - 19800825 - 20000828 - 19930811 - 20070804
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:
19850831 - 20000827 - 19870811 - 19930810 - 19800826
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 27 - 31 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF N N
SRN CALIF A N 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 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 N
MINNESOTA A B IOWA B B MISSOURI B B
ARKANSAS A B LOUISIANA A B WISCONSIN B B
ILLINOIS B B MISSISSIPPI A B MICHIGAN B B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE B B ALABAMA A N NEW YORK B N
VERMONT B N NEW HAMP B N MAINE B N
MASS B N CONN B N RHODE IS B N
PENN B B NEW JERSEY B N W VIRGINIA B B
MARYLAND B N DELAWARE B N VIRGINIA B N
N CAROLINA B A S CAROLINA B A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN N A AK WESTERN B 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 AUG 29 - SEP 04, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF N A
SRN CALIF A 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 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 A B
ARKANSAS A B LOUISIANA A B WISCONSIN A B
ILLINOIS A B MISSISSIPPI A B MICHIGAN N B
INDIANA N B OHIO B B KENTUCKY N B
TENNESSEE N B ALABAMA A B NEW YORK B B
VERMONT B N NEW HAMP B N MAINE B N
MASS B N CONN B N RHODE IS B N
PENN B B NEW JERSEY B N W VIRGINIA B B
MARYLAND B N DELAWARE B N VIRGINIA B B
N CAROLINA N N S CAROLINA N N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE A A
AK ALEUTIAN N A 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.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page