983
FXUS06 KWBC 311935
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 31 2023
6-10 DAY OUTLOOK FOR SEP 06 - 10 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, ASSOCIATED
WITH ABOVE NORMAL MEAN 500-HPA GEOPOTENTIAL HEIGHTS ACROSS THE ALEUTIANS AND
SOUTHWESTERN MAINLAND ALASKA. SLIGHTLY NEGATIVE HEIGHT ANOMALIES ARE FORECAST
ACROSS NORTHERN ALASKA. A WEAK MID-LEVEL TROUGH OVER THE NORTHEAST PACIFIC AND
WESTERN NORTH AMERICA IS SIMILARLY LOCATED IN THE MANUAL BLEND OF MODEL 500-HPA
HEIGHT FORECASTS COMPARED TO YESTERDAY’S 6-10 DAY OUTLOOK, WITH NEAR NORMAL
500-HPA HEIGHTS ACROSS THE PACIFIC NORTHWEST. ALL ENSEMBLE MODELS FAVOR STRONG
MID-LEVEL HIGH PRESSURE AND AN INCREASE IN POSITIVE 500-HPA HEIGHT ANOMALIES
OVER MUCH OF THE CONTIGUOUS UNITED STATES (CONUS) COMPARED TO YESTERDAY’S
FORECASTS, WITH THE EXCEPTION OF THE AFOREMENTIONED PACIFIC COAST, AND THE
SOUTHEAST, WHERE A TROUGH IS FORECAST NEAR THE ATLANTIC COAST.
BELOW NORMAL TEMPERATURES ARE FAVORED ACROSS CENTRAL AND SOUTHERN MAINLAND
ALASKA, UNDERNEATH MID-LEVEL LOW PRESSURE IN THE NORTH AND ANOMALOUS NORTHERLY
FLOW IN THE SOUTH. UNDERNEATH A PREDICTED MEAN MID-LEVEL TROUGH OVER THE
NORTHEAST PACIFIC, BELOW NORMAL TEMPERATURES ARE FAVORED FOR SOUTHEAST ALASKA
AND PARTS OF THE PACIFIC NORTHWEST. ABOVE NORMAL MEAN MID-LEVEL HEIGHTS
ASSOCIATED WITH THE NORTH PACIFIC RIDGE FAVOR ABOVE NORMAL TEMPERATURES ACROSS
THE WESTERN ALEUTIANS. STRONG MID-LEVEL HIGH PRESSURE ACROSS THE CENTRAL AND
EASTERN CONUS LEADS TO ENHANCED CHANCES OF ABOVE-NORMAL TEMPERATURES FROM
SOUTHERN CALIFORNIA, THE GREAT BASIN, AND THE NORTHERN ROCKIES, IN THE WEST, TO
THE ATLANTIC COAST.
AHEAD OF A MEAN MID-LEVEL TROUGH OVER THE NORTHEAST PACIFIC, NEAR TO ABOVE
NORMAL PRECIPITATION IS FAVORED FOR MUCH OF THE NORTHERN TIER WITH GREATER
CHANCES FOR ABOVE NORMAL PRECIPITATION IN PARTS OF THE PACIFIC NORTHWEST
WESTERN AREAS OF THE MIDWEST. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FOR
MUCH OF THE NORTHEAST, SUPPORTED BY MOST DYNAMICAL MODEL FORECAST TOOLS.
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, 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 0Z 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 AND PRECIPITATION.
8-14 DAY OUTLOOK FOR SEP 08 - 14 2023
DURING THE 8 TO 14 DAY PERIOD (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 ALMOST 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. HOWEVER, NEAR TO BELOW NORMAL MEAN MID-LEVEL HEIGHTS ARE
FAVORED ACROSS THE REMAINDER OF ALASKA. 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. IN
ALASKA, NEAR TO BELOW NORMAL TEMPERATURES ARE FAVORED ACROSS THE MAINLAND AND
SOUTHEAST ALASKA, UNDERNEATH BELOW NORMAL 500-HPA HEIGHTS. NEAR NORMAL
TEMPERATURES ARE FAVORED OVER THE WESTERN ALEUTIANS.
AHEAD OF A MEAN MID-LEVEL TROUGH OVER THE NORTHEAST PACIFIC, ABOVE NORMAL
PRECIPITATION IS FAVORED DURING WEEK 2 ACROSS THE PACIFIC NORTHWEST, AND
SLIGHTLY FAVORED FOR PARTS OF THE NORTHERN PLAINS. NEAR TO BELOW NORMAL
PRECIPITATION IS FAVORED ACROSS MUCH OF THE REMAINDER OF THE WESTERN AND
CENTRAL CONUS, UNDER THE INFLUENCE OF MEAN MID-LEVEL HIGH PRESSURE. HOWEVER,
POTENTIAL TROUGHING OVER THE EASTERN CONUS LEADS TO INCREASED CHANCES OF NEAR
NORMAL PRECIPITATION OVER MUCH OF THE EAST AND ELEVATED PROBABILITIES OF ABOVE
NORMAL PRECIPITATION OVER THE NORTHEAST. 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 0Z 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 MODELS IN THE PREDICTED MID-LEVEL HEIGHT PATTERN ACROSS
NORTH AMERICA, BUT WITH SOME INCREASED UNCERTAINTY WITH RESPECT TO THE
EVOLUTION OF THE OVERALL PATTERN, AND DIFFERENCES AMONG THE MODEL TEMPERATURE
AND PRECIPITATION TOOLS.
FORECASTER: D COLLINS
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:
19910816 - 19900914 - 19610820 - 19600911 - 19860830
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:
19910815 - 19600911 - 19610818 - 19570824 - 19900913
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 06 - 10 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON N N NRN CALIF N N
SRN CALIF A B IDAHO A B 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 A S DAKOTA A A
NEBRASKA A N KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA A A IOWA A A 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 N
TENNESSEE A N ALABAMA A B NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A A 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 B AK N SLOPE N A
AK ALEUTIAN N A AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST B A AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 08 - 14 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N A OREGON N A NRN CALIF N N
SRN CALIF A B IDAHO A N NEVADA A B
W MONTANA A N E MONTANA A N WYOMING A N
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 B OKLAHOMA A B
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA A N IOWA A N MISSOURI A N
ARKANSAS A B LOUISIANA A B WISCONSIN A N
ILLINOIS A N MISSISSIPPI A B MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA A N NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A A NEW JERSEY A A W VIRGINIA A N
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE N A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST B 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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