524
FXUS06 KWBC 111924
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT MON SEPTEMBER 11 2023
6-10 DAY OUTLOOK FOR SEP 17 - 21 2023
TODAY’S MODEL SOLUTIONS ARE IN GOOD AGREEMENT REGARDING AN AMPLIFIED 500-HPA
GEOPOTENTIAL HEIGHT PATTERN ACROSS NORTH AMERICA DURING DAYS 6 THROUGH 10.
MID-LEVEL TROUGHING IS FORECAST ACROSS MUCH OF ALASKA (EXCEPT FOR FLAT RIDGING
OVER THE WESTERN ALEUTIANS) AND NEAR THE WEST COAST OF THE CONTIGUOUS U.S.
(CONUS). A MID-LEVEL RIDGE AND ASSOCIATED POSITIVE HEIGHT ANOMALIES ARE
PREDICTED ACROSS THE NORTHWESTERN AND NORTH-CENTRAL CONUS. A MID-LEVEL TROUGH
AND ASSOCIATED NEGATIVE HEIGHT ANOMALIES ARE DEPICTED OVER THE EASTERN CONUS,
CENTERED NEAR THE APPALACHIANS. THE LATEST TRACK PROJECTIONS FROM THE NATIONAL
HURRICANE CENTER HAVE HURRICANE LEE NEARING THE SOUTHERN CANADIAN MARITIMES
REGION BY THE BEGINNING OF THE 6-10 DAY FORECAST PERIOD, NOT FAR EAST OF NEW
ENGLAND. EVEN IF LEE’S EYE PASSES EAST OF MAINE, HEAVY RAINFALL AND GUSTY WINDS
ARE STILL POSSIBLE ACROSS EASTERN NEW ENGLAND. GIVEN THE CONTINUED UNCERTAINTY
OF THE HURRICANE’S TRACK AND INTENSITY, NEW ENGLAND IS BY NO MEANS OUT OF THE
WOODS YET, AND RESIDENTS AND MARINERS SHOULD REMAIN VIGILANT.
00Z REFORECAST-CALIBRATED GEFS, ECMWF, AND CANADIAN ENSEMBLES AGREE ON
INCREASED CHANCES FOR ABOVE NORMAL TEMPERATURES OVER THE NORTHWESTERN AND
NORTH-CENTRAL CONUS, CONSISTENT WITH THE MID-LEVEL RIDGING AND ABOVE-NORMAL
500-HPA HEIGHTS EXPECTED OVER THAT AREA. THEY ALSO AGREE ON INCREASED CHANCES
FOR ABOVE NORMAL TEMPERATURES OVER SOUTHERN TEXAS. THE ECMWF AND GEFS AGREE ON
ELEVATED ODDS FOR ABOVE NORMAL TEMPERATURE CHANCES ACROSS THE NORTHEAST, AHEAD
OF A 500-HPA TROUGH AXIS. HOWEVER, BEYOND THIS, REFORECAST-CALIBRATED
TEMPERATURES FROM THE THREE ENSEMBLES DIVERGE DRAMATICALLY. THE GEFS
ANTICIPATES A PREDOMINANTLY WARM SOLUTION (RELATIVE TO NORMAL) ACROSS THE
REMAINDER OF THE CONUS, WHILE THE CANADIAN REFORECAST-CALIBRATED TEMPERATURES
DEPICT A PREDOMINANTLY COOL SOLUTION ACROSS THE REMAINDER OF THE CONUS. THE
ECMWF REFORECAST-CALIBRATED TEMPERATURES SPLIT THE DIFFERENCE, WITH EXPECTED
WIDESPREAD COVERAGE OF FAVORED NEAR NORMAL TEMPERATURES, AND EMBEDDED
SMALLER-SCALE AREAS OF BELOW NORMAL TEMPERATURES FAVORED OVER THE SOUTH-CENTRAL
HIGH PLAINS AND THE GREAT LAKES/MIDWEST REGION. TEMPERATURES FROM THE AUTOBLEND
AND ERF CONSOLIDATION TOOL FAVOR MOSTLY NEAR NORMAL TEMPERATURES OVER THE EAST,
WITH RELATIVELY SMALL AREAS OF BELOW NORMAL TEMPERATURES FAVORED. THE TROUGH
PREDICTED OVER CALIFORNIA INCREASES THE ODDS OF BELOW NORMAL TEMPERATURES FOR
SOUTHERN PORTIONS OF THE STATE AND NEARBY SOUTHWESTERN ARIZONA. IN ALASKA,
BELOW NORMAL TEMPERATURE CHANCES ARE SLIGHTLY INCREASED OVER SOUTHWESTERN AND
SOUTHEASTERN PORTIONS OF THE STATE, AND ABOVE NORMAL TEMPERATURE CHANCES ARE
SLIGHTLY INCREASED OVER NORTHEASTERN ALASKA.
THE MID-LEVEL TROUGH PREDICTED TO BE ALONG THE WEST COAST IN THE 6-10 DAY
PERIOD ENHANCES THE ODDS FOR ABOVE NORMAL PRECIPITATION OVER MUCH OF
CALIFORNIA, NEVADA, AND PARTS OF ADJACENT STATES. SOUTHEASTERLY RETURN FLOW
FROM THE GULF OF MEXICO TILTS THE ODDS TOWARDS ABOVE NORMAL PRECIPITATION
ACROSS MUCH OF THE CENTRAL AND SOUTHERN HIGH PLAINS REGION. MID-LEVEL RIDGING
AND NEAR TO ABOVE NORMAL 500-HPA HEIGHTS FAVOR BELOW NORMAL PRECIPITATION
ACROSS THE NORTHERN TIER OF STATES FROM WASHINGTON TO THE DAKOTAS, AND FROM THE
MISSISSIPPI VALLEY AND EASTERN TEXAS EASTWARD TO THE APPALACHIANS. THIS IS
CONSISTENT WITH TODAY’S CONSOLIDATED AND AUTOBLEND PRECIPITATION FORECASTS.
ABOVE NORMAL PRECIPITATION IS FAVORED ACROSS NEW ENGLAND AND SOUTHERN FLORIDA
IN ADVANCE OF THE EASTERN TROUGH AXIS. PROBABILITIES FOR ABOVE NORMAL
PRECIPITATION EXCEED 50% IN MAINE, CLOSER TO THE BEST-GUESS TRACK OF HURRICANE
LEE NEARLY A WEEK IN ADVANCE. IN ALASKA, WIDESPREAD ONSHORE FLOW ASSOCIATED
WITH BROAD CYCLONIC CURVATURE, MID-LEVEL TROUGHING AND BELOW NORMAL 500-HPA
HEIGHTS FAVORS ABOVE NORMAL PRECIPITATION ACROSS MOST OF THE STATE.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 34% 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: NEAR AVERAGE, 3 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG THE 500-HPA HEIGHT FORECASTS, BUT SIGNIFICANT
DISAGREEMENTS AMONG THE TEMPERATURE AND PRECIPITATION TOOLS, AND CONTINUED
UNCERTAINTY REGARDING THE FUTURE TRACK OF HURRICANE LEE.
8-14 DAY OUTLOOK FOR SEP 19 - 25 2023
ENSEMBLE MEAN SOLUTIONS FOR THE 8-14 DAY PERIOD PREDICT A FAIRLY PERSISTENT
500-HPA GEOPOTENTIAL HEIGHT PATTERN ACROSS NORTH AMERICA. THE WEEK-2 MANUAL
HEIGHT BLEND DEPICTS ANOMALOUS RIDGING OVER THE WESTERN ALEUTIANS, AND
TROUGHING ACROSS MUCH OF DOWNSTREAM ALASKA. OVER THE LOWER 48 STATES, A SLIGHT
EASTWARD DISPLACEMENT OF THE MEAN TROUGH-RIDGE-TROUGH PATTERN IS FORECAST,
ALONG WITH A WEAKENING OF THE CIRCULATION ANOMALIES. THE 00Z CANADIAN ENSEMBLE
MEAN IS THE MOST PROGRESSIVE WITH THE CENTRAL CONUS RIDGE, PREDICTING IT AS FAR
EAST AS THE MISSISSIPPI VALLEY.
THE TEMPERATURE PATTERN FORECAST FOR THE WEEK 2 PERIOD IS GENERALLY SIMILAR TO
THE 6-10 DAY TEMPERATURE OUTLOOK, BUT WITH SOME MODERATION EXPECTED OVER THE
EASTERN HALF OF THE CONUS. WEST OF THE CONTINENTAL DIVIDE, THERE ARE ENHANCED
ODDS OF ABOVE NORMAL TEMPERATURES ACROSS APPROXIMATELY THE NORTHERN HALF OF
THIS REGION, AND NEAR TO BELOW NORMAL TEMPERATURES OVER APPROXIMATELY THE
SOUTHERN HALF OF THIS REGION, CONSISTENT WITH THE AUTOBLEND TEMPERATURE
FORECAST. FROM THE CONTINENTAL DIVIDE EASTWARD TO THE ATLANTIC COAST, MOSTLY
ABOVE NORMAL TEMPERATURE PROBABILITIES ARE FAVORED, SUPPORTED BY GFS AND ECMWF
ENSEMBLE MEAN CALIBRATED-REFORECAST TEMPERATURES. A RELATIVELY SMALL REGION OF
FAVORED NEAR NORMAL TEMPERATURES IS DEPICTED FOR PARTS OF THE SOUTHERN
APPALACHIANS AND SOUTHEAST. IN ALASKA, BELOW NORMAL TEMPERATURE CHANCES ARE
ELEVATED OVER SOUTHEAST ALASKA, AND ABOVE NORMAL TEMPERATURE CHANCES ARE
ENHANCED OVER THE NORTHEASTERN MAINLAND.
THE MID-LEVEL TROUGH PREDICTED JUST INLAND OF THE WEST COAST FAVORS INCREASED
ODDS FOR ABOVE NORMAL PRECIPITATION ACROSS MUCH OF THE WESTERN HALF OF THE
CONUS. BELOW NORMAL PRECIPITATION CHANCES ARE ENHANCED FOR EASTERN TEXAS, AND
FROM MOST OF THE MISSISSIPPI VALLEY EASTWARD TO NEAR THE APPALACHIANS IN THE
DRIER AIR ON THE BACKSIDE OF THE TROUGH CENTERED NEAR THE ATLANTIC COAST. NEAR
NORMAL PRECIPITATION IS FAVORED ALONG THE ATLANTIC COASTAL PLAIN, WITH ABOVE
NORMAL PRECIPITATION STILL POSSIBLE IN MAINE EARLY IN WEEK-2 DEPENDING ON THE
SPEED AND TRACK OF HURRICANE LEE. TROUGHING CONTINUES TO FAVOR ELEVATED
PROBABILITIES FOR ABOVE NORMAL PRECIPITATION ACROSS MOST OF ALASKA, WITH ODDS
EXCEEDING 40% ACROSS THE COPPER RIVER BASIN OF SOUTHEAST ALASKA AND THE
PANHANDLE REGION.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 34% 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: AVERAGE, 3 OUT OF 5, DUE TO GOOD
AGREEMENT AMONG MODEL ENSEMBLES ON THE PERSISTENT SYNOPTIC PATTERN, OFFSET BY
SOME DIFFERENCES AMONG THE TEMPERATURE AND PRECIPITATION TOOLS.
FORECASTER: ANTHONY A
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:
20010924 - 20060902 - 19620925 - 20090912 - 19870921
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:
20010922 - 20060902 - 20090913 - 20090827 - 19530907
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 17 - 21 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A N NRN CALIF A A
SRN CALIF B N IDAHO A N NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A N
UTAH A N ARIZONA A N COLORADO A A
NEW MEXICO A A N DAKOTA A B S DAKOTA A B
NEBRASKA A N KANSAS A A OKLAHOMA N A
N TEXAS A N S TEXAS A N W TEXAS A A
MINNESOTA A B IOWA A B MISSOURI N B
ARKANSAS N B LOUISIANA A B WISCONSIN A B
ILLINOIS N B MISSISSIPPI A B MICHIGAN N B
INDIANA N B OHIO N B KENTUCKY B B
TENNESSEE N B ALABAMA N B NEW YORK N N
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN N N NEW JERSEY N N W VIRGINIA N B
MARYLAND N N DELAWARE N N VIRGINIA N B
N CAROLINA N N S CAROLINA N N GEORGIA N N
FL PNHDL N N FL PENIN A N AK N SLOPE N A
AK ALEUTIAN N A AK WESTERN N A AK INT BSN N A
AK S INT N A AK SO COAST N A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 19 - 25 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF N A
SRN CALIF B A IDAHO A A NEVADA N A
W MONTANA A N E MONTANA A N WYOMING A A
UTAH A A ARIZONA B N COLORADO A A
NEW MEXICO A N N DAKOTA A N S DAKOTA A N
NEBRASKA A A KANSAS A A OKLAHOMA A N
N TEXAS A N S TEXAS A B W TEXAS A N
MINNESOTA A N IOWA A N MISSOURI A N
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 N
VERMONT A N NEW HAMP A N MAINE A A
MASS A N CONN A N RHODE IS A N
PENN A B NEW JERSEY A N W VIRGINIA A B
MARYLAND A N DELAWARE A N VIRGINIA A N
N CAROLINA A N S CAROLINA N N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE N A
AK ALEUTIAN N N AK WESTERN N A AK INT BSN N A
AK S INT N 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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