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FXUS06 KWBC 301902
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 30 2023
6-10 DAY OUTLOOK FOR SEP 05 - 09 2023
THERE IS GOOD AGREEMENT AMONG THE MODELS WITH RESPECT TO THE PREDICTED MEAN
500-HPA HEIGHT PATTERN ACROSS NORTH AMERICA DURING THE NEXT 6 TO 10 DAYS.
STRONG MID-LEVEL HIGH PRESSURE IS FORECAST OVER THE NORTH PACIFIC, FAVORING
ABOVE NORMAL MEAN 500-HPA GEOPOTENTIAL HEIGHTS ACROSS SOUTHERN MAINLAND ALASKA
AND THE ALEUTIANS. HOWEVER, A MEAN MID-LEVEL TROUGH OVER SIBERIA HAS SHIFTED
EASTWARD IN TODAY’S OUTLOOK, HELPING TO SUPPRESS THE NORTH PACIFIC RIDGE,
LEADING TO INCREASED NEGATIVE HEIGHT ANOMALIES ACROSS NORTHERN ALASKA.
PREDICTED MID-LEVEL TROUGHING OVER WESTERN NORTH AMERICA AND THE NORTHEAST
PACIFIC CONTINUES TO DEAMPLIFY, COMPARED TO YESTERDAY’S 6-10 DAY OUTLOOK,
FAVORING NEAR NORMAL 500-HPA HEIGHTS ACROSS THE PACIFIC NORTHWEST. ELSEWHERE
OVER THE CONTIGUOUS UNITED STATES (CONUS), STRONG MID-LEVEL HIGH PRESSURE
FAVORS NEAR TO ABOVE NORMAL 500-HPA HEIGHTS. DESPITE THE STRONG MEAN MID-LEVEL
RIDGE OVER EASTERN NORTH AMERICA, THE FLOW PATTERN ACROSS THE EASTERN
TWO-THIRDS OF THE CONUS HAS BECOME MORE ZONAL (WEST-EAST ORIENTED), COMPARED TO
YESTERDAY’S 6-10 DAY OUTLOOK.
UNDERNEATH A PREDICTED MEAN MID-LEVEL TROUGH OVER THE NORTHEAST PACIFIC, BELOW
NORMAL TEMPERATURES ARE FAVORED ACROSS PARTS OF THE PACIFIC NORTHWEST.
CONVERSELY, STRONG MID-LEVEL HIGH PRESSURE IS FAVORED ACROSS THE CENTRAL AND
EASTERN CONUS, LEADING TO ENHANCED CHANCES OF ABOVE NORMAL TEMPERATURES FROM
THE EASTERN ROCKIES TO THE EAST COAST, WITH ABOVE NORMAL TEMPERATURE
PROBABILITIES ALSO EXTENDING INTO THE FOUR CORNERS REGION, AS THE PREDICTED
MID-LEVEL RIDGE HAS CONTINUED TO BUILD WESTWARD IN RECENT DAYS. NEAR TO BELOW
NORMAL TEMPERATURES ARE FAVORED ACROSS MUCH OF THE ALASKA MAINLAND AND
PANHANDLE, UNDERNEATH MID-LEVEL LOW PRESSURE. BELOW NORMAL TEMPERATURE
PROBABILITIES CONTINUE TO DECREASE, COMPARED TO YESTERDAY’S 6-10 DAY OUTLOOK,
DUE TO MODEL UNCERTAINTY ACROSS THE NORTH PACIFIC. ABOVE NORMAL MEAN MID-LEVEL
HEIGHTS ASSOCIATED WITH THE NORTH PACIFIC RIDGE FAVOR ABOVE NORMAL TEMPERATURES
ACROSS THE ALASKA PENINSULA AND THE ALEUTIANS. MEAN SURFACE LOW PRESSURE NEAR
THE BERING STRAIT COULD PROMOTE SOUTHERLY DOWNSLOPE FLOW ALONG THE NORTH SLOPE,
LEADING TO A TILT IN THE ODDS TOWARD ABOVE NORMAL TEMPERATURES NORTH OF THE
BROOKS RANGE.
ALONG AND AHEAD OF A MEAN MID-LEVEL TROUGH OVER WESTERN NORTH AMERICA AND THE
NORTHWEST PACIFIC, ODDS TILT TOWARD ABOVE NORMAL PRECIPITATION ACROSS PARTS OF
THE NORTHERN TIER FROM THE PACIFIC NORTHWEST TO THE UPPER MIDWEST. ELSEWHERE
ACROSS THE LOWER 48, NEAR TO BELOW NORMAL PRECIPITATION IS PREDICTED UNDERNEATH
STRONG MID-LEVEL HIGH PRESSURE. HOWEVER, THERE IS SOME UNCERTAINTY WITH RESPECT
TO THE PRECIPITATION OUTLOOK ACROSS THE CENTRAL AND EASTERN CONUS, AS THE ECMWF
ENSEMBLE REFORECAST GUIDANCE FAVORS A TILT IN THE ODDS TOWARD ABOVE NORMAL
PRECIPITATION ACROSS PARTS OF THE MISSISSIPPI VALLEY, CONTRARY TO MOST OTHER
FORECAST TOOLS. IN ADDITION, THE MID-LEVEL RIDGE IS MORE SUPPRESSED ACROSS THE
CONUS, COMPARED TO YESTERDAY’S 6-10 DAY OUTLOOK, RESULTING IN MORE ZONAL FLOW
AND A MORE PROGRESSIVE PATTERN ACROSS THE NORTHERN TIER OF THE LOWER 48. 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: AVERAGE, 3 OUT OF 5, DUE TO GOOD
AGREEMENT AMONG DYNAMICAL MODEL SOLUTIONS IN THE PREDICTED MEAN MID-LEVEL
HEIGHT PATTERN ACROSS NORTH AMERICA, OFFSET BY MODEL UNCERTAINTY IN THE
PREDICTED TEMPERATURE FIELDS ACROSS ALASKA AND PRECIPITATION FIELDS ACROSS THE
CENTRAL CONUS.
8-14 DAY OUTLOOK FOR SEP 07 - 13 2023
DURING THE NEXT 8 TO 14 DAYS (WEEK 2), THE MEAN MID-LEVEL TROUGH OF LOW
PRESSURE OVER WESTERN NORTH AMERICA IS FORECAST TO DEAMPLIFY, WITH ABOVE NORMAL
MEAN MID-LEVEL GEOPOTENTIAL HEIGHTS OVERTAKING ALL OF THE CONUS AS A RESULT.
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 THE ALASKA PENINSULA. HOWEVER, NEAR TO BELOW NORMAL
MEAN MID-LEVEL HEIGHTS ARE FAVORED ACROSS THE REMAINDER OF ALASKA, UNDERNEATH
MID-LEVEL TROUGHING THAT HAS SHIFTED EASTWARD FROM SIBERIA, COMPARED TO
YESTERDAY’S WEEK 2 OUTLOOK. THERE IS SOME DISAGREEMENT BETWEEN TODAY’S GEFS AND
ECMWF ENSEMBLE MODEL SOLUTIONS WITH RESPECT TO THE STRENGTH OF THE NORTH
PACIFIC RIDGE, ADDING SOME UNCERTAINTY IN THE PREDICTED MEAN MID-LEVEL HEIGHT
FIELDS ACROSS ALASKA.
NEAR TO BELOW NORMAL TEMPERATURES ARE FAVORED ACROSS PARTS OF THE PACIFIC
NORTHWEST, UNDERNEATH A TROUGH 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 THAT
CONTINUES TO BUILD WESTWARD IN TODAY’S OUTLOOK. IN ALASKA, NEAR TO BELOW NORMAL
TEMPERATURES ARE FAVORED ACROSS THE MAINLAND AND THE PANHANDLE, UNDERNEATH
BELOW NORMAL 500-HPA HEIGHTS. ABOVE NORMAL TEMPERATURES ARE WEAKLY FAVORED
ACROSS THE ALEUTIANS, ON THE NORTHERN PERIPHERY OF A PREDICTED NORTH PACIFIC
RIDGE OF HIGH PRESSURE.
AHEAD OF A MEAN MID-LEVEL TROUGH OVER THE NORTHEAST PACIFIC, ABOVE NORMAL
PRECIPITATION IS FAVORED DURING WEEK 2 ACROSS PARTS OF THE PACIFIC NORTHWEST.
NEAR TO BELOW NORMAL PRECIPITATION IS FAVORED ACROSS MUCH OF THE REMAINDER OF
THE CONUS, UNDER THE INFLUENCE OF A PREDICTED BROAD REGION OF MEAN MID-LEVEL
HIGH PRESSURE. HOWEVER, THERE IS A SLIGHT BREAK-DOWN OF THE PREDICTED MEAN
MID-LEVEL RIDGE ACROSS EASTERN NORTH AMERICA IN TODAY’S MODEL SOLUTIONS,
INTRODUCING SLIGHT CYCLONIC FLOW OVER THE EASTERN CONUS, LEADING TO NEAR TO
ELEVATED ABOVE NORMAL PRECIPITATION CHANCES ACROSS THE EASTERN SEABOARD. IN
ALASKA, AN ACTIVE STORM TRACK IS PREDICTED, 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 OVERALL PATTERN.
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:
19610820 - 19600910 - 19910816 - 19670817 - 19630829
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:
19610819 - 19600910 - 19910815 - 19670817 - 19630829
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 05 - 09 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B N OREGON N N NRN CALIF N B
SRN CALIF N B IDAHO N N 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 N KANSAS A N OKLAHOMA A N
N TEXAS A B S TEXAS A N W TEXAS A B
MINNESOTA A N IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA A B WISCONSIN A N
ILLINOIS A N MISSISSIPPI A B MICHIGAN A N
INDIANA A N OHIO A N 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 N NEW JERSEY A N W VIRGINIA A N
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A B S CAROLINA A B GEORGIA A B
FL PNHDL A B FL PENIN A B AK N SLOPE N A
AK ALEUTIAN A A AK WESTERN B A AK INT BSN N A
AK S INT N A AK SO COAST N A AK PNHDL N N
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 07 - 13 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N N OREGON N N NRN CALIF N N
SRN CALIF A B IDAHO A N NEVADA A B
W MONTANA A N 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 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 A B OHIO A N KENTUCKY A B
TENNESSEE A B ALABAMA A B NEW YORK A N
VERMONT A N NEW HAMP A A MAINE A N
MASS A A CONN A A RHODE IS A A
PENN A N NEW JERSEY A A W VIRGINIA A N
MARYLAND A A DELAWARE A A VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A B FL PENIN A N AK N SLOPE N A
AK ALEUTIAN A N AK WESTERN B A AK INT BSN N 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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