694
FXUS06 KWBC 291902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE AUGUST 29 2023
6-10 DAY OUTLOOK FOR SEP 04 - 08 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. ALTHOUGH WEAKER, COMPARED TO YESTERDAY’S 6-10 DAY
OUTLOOK, MEAN MID-LEVEL LOW PRESSURE OVER THE ARCTIC OCEAN AND MUCH OF WESTERN
NORTH AMERICA FAVORS NEGATIVE MID-LEVEL HEIGHT ANOMALIES ACROSS THE REMAINDER
OF ALASKA AND EXTENDING SOUTHEASTWARD OVER NORTHERN PARTS OF THE INTERMOUNTAIN
WEST AND GREAT BASIN OF THE 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 MUCH OF THE INTERMOUNTAIN WEST. 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 ALSO EXTENDING INTO THE FOUR
CORNERS REGION. NEAR TO BELOW NORMAL TEMPERATURES ARE FAVORED ACROSS THE ALASKA
MAINLAND AND PANHANDLE, UNDERNEATH MID-LEVEL LOW PRESSURE. HOWEVER, BELOW
NORMAL TEMPERATURE PROBABILITIES ARE LOWER, COMPARED TO YESTERDAY’S 6-10 DAY
OUTLOOK, DUE TO WEAKER NEGATIVE HEIGHT ANOMALIES ACROSS NORTHERN ALASKA. ABOVE
NORMAL MEAN MID-LEVEL HEIGHTS ASSOCIATED WITH THE NORTH PACIFIC RIDGE FAVOR
ABOVE NORMAL TEMPERATURES ACROSS THE ALEUTIANS.
ALONG AND AHEAD OF A BROAD MEAN MID-LEVEL TROUGH OVER WESTERN NORTH AMERICA,
ENHANCED CHANCES OF ABOVE NORMAL PRECIPITATION ARE FAVORED ACROSS THE
NORTHWESTERN CONUS AND EXTENDING ACROSS THE NORTHERN TIER STATES 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 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 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 SOME DIFFERENCES IN THE
PREDICTED PRECIPITATION FIELDS ACROSS THE CENTRAL CONUS.
8-14 DAY OUTLOOK FOR SEP 06 - 12 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 THE ALASKA PENINSULA. HOWEVER, NEAR TO BELOW NORMAL
MEAN MID-LEVEL HEIGHTS ARE FAVORED ACROSS THE REMAINDER OF ALASKA, UNDERNEATH
WEAKENING MID-LEVEL TROUGHING.
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 MUCH OF THE MAINLAND AND
PARTS OF THE PANHANDLE, UNDERNEATH BELOW NORMAL 500-HPA HEIGHTS. HOWEVER,
NEGATIVE MID-LEVEL HEIGHT ANOMALIES ARE REDUCED, COMPARED TO YESTERDAY’S WEEK 2
OUTLOOK. ASSOCIATED WITH MEAN SURFACE LOW PRESSURE PREDICTED OVER THE BERING
SEA, SOUTHERLY DOWNSLOPE FLOW MAY LEAD TO ADIABATIC WARMING, FAVORING A TILT IN
THE ODDS TOWARD ABOVE NORMAL TEMPERATURES ALONG THE NORTH SLOPE. ABOVE NORMAL
TEMPERATURES ARE ALSO WEAKLY FAVORED ACROSS THE ALASKA PENINSULA AND PARTS OF
THE ALEUTIANS, ON THE NORTHERN PERIPHERY OF A PREDICTED NORTH PACIFIC RIDGE OF
HIGH PRESSURE.
AHEAD OF A MEAN MID-LEVEL TROUGH OVER WESTERN CANADA AND THE NORTHEAST PACIFIC,
ABOVE NORMAL PRECIPITATION IS FAVORED DURING WEEK 2 IN THE PACIFIC NORTHWEST.
NEAR TO BELOW NORMAL PRECIPITATION IS FAVORED ELSEWHERE ACROSS THE CONUS, UNDER
THE INFLUENCE OF A PREDICTED BROAD REGION OF MEAN MID-LEVEL HIGH PRESSURE. AN
ACTIVE STORM TRACK IS PREDICTED 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
PRECIPITATION OUTLOOK ACROSS THE EASTERN CONUS.
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:
19610819 - 19600910 - 19630829 - 20070910 - 19560910
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 - 19600910 - 19630828 - 19940808 - 19670816
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 04 - 08 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 B B
W MONTANA N A E MONTANA A A WYOMING A A
UTAH B 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 N W TEXAS A B
MINNESOTA A A IOWA A N MISSOURI A N
ARKANSAS A B LOUISIANA A N WISCONSIN A N
ILLINOIS A N MISSISSIPPI A B MICHIGAN A N
INDIANA A N 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 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 N 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 A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 06 - 12 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF N N
SRN CALIF N B IDAHO N A NEVADA N 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 N MISSOURI A B
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 B
TENNESSEE A B ALABAMA A N 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 N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE N A
AK ALEUTIAN A N AK WESTERN N A AK INT BSN N A
AK S INT N A AK SO COAST N A AK PNHDL B N
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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