801
FXUS06 KWBC 281902
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 28 2023
6-10 DAY OUTLOOK FOR SEP 03 - 07 2023
THERE IS GOOD AGREEMENT AMONG THE MODELS IN PREDICTING AN AMPLIFIED MEAN
500-HPA HEIGHT PATTERN ACROSS NORTH AMERICA DURING THE NEXT 6 TO 10 DAYS. A
STRONG MID-LEVEL HIGH PRESSURE IS FORECAST OVER THE NORTH PACIFIC, FAVORING
ABOVE NORMAL MEAN 500-HPA GEOPOTENTIAL HEIGHTS ACROSS SOUTHWESTERN MAINLAND
ALASKA AND THE ALEUTIANS. OVER THE ARCTIC OCEAN AND MUCH OF WESTERN NORTH
AMERICA, MID-LEVEL LOW PRESSURE FAVORS NEGATIVE MID-LEVEL HEIGHT ANOMALIES
ACROSS THE REMAINDER OF ALASKA AND EXTENDING SOUTHEASTWARD OVER MUCH OF THE
INTERMOUNTAIN WEST OF CONTIGUOUS UNITED STATES (CONUS). ELSEWHERE OVER THE
CONUS, STRONG 500-HPA HIGH PRESSURE FAVORS NEAR TO ABOVE NORMAL MID-LEVEL
HEIGHTS.
UNDERNEATH A PREDICTED MEAN MID-LEVEL TROUGH, BELOW NORMAL TEMPERATURES ARE
FAVORED ACROSS THE WEST COAST, GREAT BASIN, AND NORTHERN ROCKIES. CONVERSELY,
STRONG MID-LEVEL HIGH PRESSURE IS FAVORED ACROSS THE CENTRAL AND EASTERN CONUS,
LEADING TO ENHANCED CHANCES OF ABOVE NORMAL TEMPERATURES FROM THE GREAT PLAINS
TO THE EAST COAST, WITH ABOVE NORMAL TEMPERATURE PROBABILITIES EXTENDING INTO
THE FOUR CORNERS REGION. ENHANCED PROBABILITIES OF BELOW NORMAL TEMPERATURES
ARE FAVORED ACROSS THE ALASKA MAINLAND AND PANHANDLE, UNDERNEATH MID-LEVEL LOW
PRESSURE. ABOVE NORMAL MEAN MID-LEVEL HEIGHTS FAVOR ABOVE NORMAL TEMPERATURES
ACROSS THE ALEUTIANS.
ALONG AND AHEAD OF A STRONG MEAN MID-LEVEL TROUGH OVER WESTERN NORTH AMERICA,
ENHANCED CHANCES OF ABOVE NORMAL PRECIPITATION ARE FAVORED ACROSS THE
NORTHWESTERN CONUS. ELSEWHERE ACROSS THE LOWER 48, NEAR TO BELOW NORMAL
PRECIPITATION IS PREDICTED UNDERNEATH STRONG MID-LEVEL HIGH PRESSURE. IN
ALASKA, A STRONG PRESSURE GRADIENT BETWEEN MID-LEVEL HIGH PRESSURE OVER THE
NORTH PACIFIC AND LOW PRESSURE OVER THE ARCTIC PROMOTES AN ACTIVE STORM TRACK
ACROSS ALASKA, FAVORING ENHANCED PROBABILITIES OF ABOVE NORMAL PRECIPITATION
ACROSS MOST OF THE STATE.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 50% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, AND 50% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG DYNAMICAL MODEL SOLUTIONS IN THE PREDICTED MEAN MID-LEVEL
HEIGHT PATTERN ACROSS NORTH AMERICA, OFFSET BY RUN-TO-RUN MODEL INCONSISTENCY
WITH RESPECT TO THE MEAN MID-LEVEL HEIGHT PATTERN OVER THE NORTH PACIFIC IN THE
GEFS.
8-14 DAY OUTLOOK FOR SEP 05 - 11 2023
DURING THE NEXT 8 TO 14 DAYS (WEEK 2), THE MEAN MID-LEVEL TROUGH OF LOW
PRESSURE OVER WESTERN NORTH AMERICA AND EXTENDING INTO THE ARCTIC OCEAN IS
FORECAST TO DEAMPLIFY, WITH ABOVE NORMAL MEAN MID-LEVEL GEOPOTENTIAL HEIGHTS
OVERTAKING MOST OF THE CONUS AS A RESULT. THE EXCEPTION IS THE PACIFIC
NORTHWEST, WHERE WEAK NEGATIVE MID-LEVEL HEIGHTS ANOMALIES ARE STILL FAVORED.
SIMILAR TO THE 6-10 DAY PERIOD, A STRONG 500-HPA RIDGE OF HIGH PRESSURE IS
FORECAST OVER THE NORTH PACIFIC, LEADING TO ABOVE NORMAL MID-LEVEL HEIGHTS
ACROSS THE ALEUTIANS AND SOUTHWESTERN MAINLAND ALASKA. HOWEVER, NEAR TO BELOW
NORMAL MEAN MID-LEVEL HEIGHTS ARE FAVORED ACROSS THE REMAINDER OF ALASKA,
UNDERNEATH WEAKENING MID-LEVEL TROUGHING. RECENT GEFS MODEL RUNS INDICATE A
POTENTIAL BREAKDOWN OF THE NORTH PACIFIC RIDGE DURING WEEK 2, POTENTIALLY
RELATED TO THE EXTRATROPICAL TRANSITION OF TROPICAL CYCLONES IN THE WEST
PACIFIC, THAT WILL NEED TO BE MONITORED IN THE COMING DAYS.
BELOW NORMAL TEMPERATURES ARE FAVORED ACROSS THE WEST COAST, WESTERN GREAT
BASIN, AND PARTS OF THE NORTHERN ROCKIES, UNDERNEATH A RIDGE THAT IS FORECAST
TO DEAMPLIFY DURING WEEK 2. ELSEWHERE ACROSS THE CONUS, ENHANCED CHANCES OF
ABOVE NORMAL TEMPERATURES ARE FAVORED, ASSOCIATED WITH A BROAD REGION OF STRONG
MID-LEVEL HIGH PRESSURE. IN ALASKA, BELOW NORMAL TEMPERATURES ARE FAVORED
ACROSS MUCH OF THE MAINLAND AND PARTS OF THE PANHANDLE, UNDERNEATH BELOW NORMAL
500-HPA HEIGHTS. ABOVE NORMAL TEMPERATURES ARE WEAKLY FAVORED ACROSS PARTS OF
THE ALEUTIANS, ON THE NORTHERN PERIPHERY OF THE NORTH PACIFIC RIDGE OF HIGH
PRESSURE.
ALONG AND AHEAD OF A MEAN MID-LEVEL TROUGH OVER WESTERN CANADA AND THE PACIFIC
NORTHWEST, ABOVE NORMAL PRECIPITATION IS FAVORED DURING WEEK 2. NEAR TO BELOW
NORMAL PRECIPITATION IS FAVORED ELSEWHERE ACROSS THE CONUS, UNDER THE INFLUENCE
OF A PREDICTED BROAD REGION MEAN MID-LEVEL HIGH PRESSURE. AN ACTIVE STORM TRACK
IS FAVORED ACROSS ALASKA, FAVORING INCREASED CHANCES OF ABOVE NORMAL
PRECIPITATION FOR MOST OF THE STATE.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 45% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, AND 55% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO GOOD
AGREEMENT AMONG THE TOOLS IN THE PREDICTED MID-LEVEL HEIGHT PATTERN ACROSS MUCH
OF NORTH AMERICA, BUT WITH SOME INCREASED UNCERTAINTY WITH RESPECT TO THE
EVOLUTION OF THE PATTERN OVER THE NORTH PACIFIC.
FORECASTER: ADAM HARTMAN
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:
19610818 - 19790820 - 19560911 - 19630829 - 20070910
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:
19610818 - 19630828 - 19790821 - 19560910 - 20070909
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 03 - 07 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 A A
UTAH B A ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A A 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 B 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 B NEW YORK A B
VERMONT A B NEW HAMP A B MAINE A B
MASS A B CONN A B RHODE IS A B
PENN A B NEW JERSEY A B 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 B AK N SLOPE B A
AK ALEUTIAN A N AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST N N AK PNHDL B N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 05 - 11 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B N
SRN CALIF B B IDAHO B A NEVADA N B
W MONTANA N A E MONTANA A N WYOMING A B
UTAH A B ARIZONA A B COLORADO A B
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 N 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 B
VERMONT A B NEW HAMP A N MAINE A N
MASS A B CONN A B RHODE IS A N
PENN A B NEW JERSEY A B 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 N A
AK ALEUTIAN A A AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST N A AK PNHDL N A
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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