462
FXUS06 KWBC 071934
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 07 2023
6-10 DAY OUTLOOK FOR AUG 13 - 17 2023
THE GFS, ECMWF, AND CANADIAN ENSEMBLE MEANS AND THE 0Z DETERMINISTIC ECMWF
MODELS ARE IN VERY GOOD AGREEMENT ON THE PREDICTED LONGWAVE PATTERN DURING THE
6-10 DAY PERIOD. THE MANUAL 500-HPA HEIGHT BLEND FEATURES A DEEP, ANOMALOUS
TROUGH CENTERED OVER THE ALEUTIANS, AN AMPLIFIED RIDGE OVER WESTERN NORTH
AMERICA, A BROAD AREA OF ANOMALOUSLY HIGH 500-HPA HEIGHTS ALONG THE SOUTHERN
CONUS, AND A MODERATE MID-LEVEL TROUGH CENTERED NEAR THE GREAT LAKES. THIS IS
THE GENERAL PATTERN AGREED UPON BY MOST GUIDANCE FOR THE PAST SEVERAL DAYS WITH
GREAT CONSISTENCY BETWEEN THE MODELS, AND FROM RUN-TO-RUN.
DESPITE THIS BROAD PATTERN AGREEMENT, THERE IS CONSIDERABLY LESS CONSISTENCY IN
THE VARIOUS TEMPERATURE AND PRECIPITATION TOOLS, SUCH AS THE CALIBRATED,
RE-FORECAST, AND CONSOLIDATED TOOLS. THE FORECAST LEANS TOWARD THE CONSOLIDATED
TOOLS AND THE OTHER GUIDANCE THAT HAS BEEN MOST CONSISTENT OF LATE, AND MOST
ACCURATE OVER THE PAST FEW WEEKS. IN SOME CASES, OBSERVATIONS OVER THE PAST FEW
WEEKS WITH SIMILAR PATTERNS WERE CONSIDERED, WHICH DIDN’T AGREE PARTICULARLY
WELL WITH ANY OF THE TOOLS AT THE TIME.
THE AMPLIFIED TROUGH FAVORS BELOW NORMAL TEMPERATURES FOR THE ALEUTIANS AND THE
SOUTHERN TIER OF ALASKA WHILE SOUTHERLY SURFACE FLOW SUPPORTS INCREASED
ABOVE-NORMAL TEMPERATURE PROBABILITIES FOR THE REMAINDER OF ALASKA, ESPECIALLY
SOUTHEASTERN AREAS. ANOMALOUS RIDGING SUPPORTS INCREASED ABOVE-NORMAL
TEMPERATURE PROBABILITIES THROUGHOUT THE WESTERN AND SOUTHERN CONUS. LATE LAST
WEEK, IT APPEARED AS THOUGH THE 500-HPA HEIGHTS IN THE SOUTHERN AND WESTERN
CONUS WOULD BEGIN TO DROP TOWARD NEXT WEEKEND, WHICH WOULD HAVE ALLOWED EXTREME
HEAT IN THESE REGIONS TO EASE. TODAY’S GUIDANCE, HOWEVER, KEEPS ABOVE-NORMAL
HEIGHTS IN THESE AREAS, KEEPING SIGNIFICANTLY-ENHANCED CHANCES FOR WARMER THAN
NORMAL TEMPERATURES IN THE SOUTHERN AND WESTERN CONUS. SOUTHERLY FLOW AHEAD OF
THE GREAT LAKES MID-LEVEL TROUGH INCREASES THE ODDS FOR ABOVE-NORMAL
TEMPERATURES ALONG THE EASTERN SEABOARD AS WELL. MEANWHILE, SUBNORMAL
TEMPERATURES ARE FAVORED FROM THE NORTHERN HIGH PLAINS EASTWARD THROUGH THE
GREAT LAKES IN CONJUNCTION WITH THE MEAN MID-LEVEL TROUGH AND ANTICYCLONIC FLOW
TO ITS WEST. THIS IS CONSISTENT WITH THE CONSOLIDATED FORECAST AND THE ECMWF
AND CANADIAN RE-FORECAST TOOLS.
THE MID-LEVEL TROUGH OVER EASTERN NORTH AMERICA FAVORS INCREASED ABOVE NORMAL
PRECIPITATION PROBABILITIES ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS
FAVORED WETNESS EXTENDS AS FAR SOUTH AS THE SOUTHERN REACHES OF THE MIDDLE
MISSISSIPPI VALLEY, THE INTERIOR DEEP SOUTH, AND THE SOUTHERN MID-ATLANTIC
REGION. SEVERAL TOOLS FAVOR ABOVE-NORMAL PRECIPITATION FARTHER SOUTH AS WELL,
FROM CENTRAL TEXAS EASTWARD ACROSS THE GULF COAST STATES. HOWEVER, OBSERVED
RAINFALL AMOUNTS IN THIS REGION HAVE BEEN CONSIDERABLY LOWER THAN INDICATED BY
GUIDANCE RECENTLY, AND THE CURRENT FORECAST IS CONSISTENT WITH OBSERVED
PRECIPITATION AMOUNTS DURING THE PAST FEW WEEKS UNDER A SIMILAR 500-HPA HEIGHT
PATTERN. FARTHER WEST, THE ANOMALOUS 500-HPA RIDGE FAVORS BELOW-NORMAL
PRECIPITATION ACROSS THE SOUTHWEST, CONSISTENT WITH A PATTERN THAT WOULD
INHIBIT THE MONSOON CIRCULATION. THE DRIER TOOLS WERE PREFERRED FOR THE PACIFIC
NORTHWEST AND INTERMOUNTAIN WEST GIVEN THE STRENGTH OF THE RIDGE ALOFT.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 20% OF TODAY'S GFS
SUPERENSEMBLE MEAN CENTERED ON DAY 8, 35% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, 25% OF TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8, AND
20% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO
EXCELLENT AGREEMENT ON THE LONGWAVE PATTERN, REDUCED BY INCONSISTENCY IN
TEMPERATURE AND PRECIPITATION GUIDANCE ALONG WITH OBSERVATIONS OVER THE PAST
FEW WEEKS.
8-14 DAY OUTLOOK FOR AUG 15 - 21 2023
ENSEMBLE MEANS ARE IN GOOD AGREEMENT THAT THE LONGWAVE PATTERN OVER THE NORTH
PACIFIC AND NORTH AMERICA BECOMES STABLE DURING MID-AUGUST WITH A PERSISTENT
ANOMALOUS TROUGH OF MODERATE STRENGTH OVER THE BERING SEA AND ALEUTIANS, AND AN
AMPLIFIED RIDGE ACROSS THE NORTHEAST PACIFIC AND WESTERN CONUS. SOMEWHAT
ABOVE-NORMAL 500-HPA HEIGHTS PERSIST ALONG THE SOUTHERN TIER OF THE CONUS, AND
THE MID-LEVEL TROUGH CENTERED NEAR THE GREAT LAKES IS EXPECTED TO WEAKEN
SLIGHTLY WHILE REMAINING NEARLY STATIONARY OR DRIFTING SLIGHTLY TO THE NORTH OR
NORTHWEST. THIS PATTERN CONTINUES TO SUPPORT INCREASED ABOVE NORMAL TEMPERATURE
PROBABILITIES THROUGHOUT THE WESTERN AND SOUTHERN CONUS. BASED ON GOOD MODEL
CONTINUITY AND AGREEMENT BETWEEN THE DYNAMICAL MODEL OUTPUT, THE CALIBRATED AND
RE-FORECAST TOOLS, AND THE ANALOG GUIDANCE, PROBABILITIES FOR ABOVE NORMAL
TEMPERATURES EXCEED 70 PERCENT ACROSS PARTS OF SOUTHWEST OREGON AND NORTHERN
CALIFORNIA. MEANWHILE, THE TROUGH FARTHER EAST AND PERIODIC NORTHERLY SURFACE
FLOW FAVORS BELOW NORMAL TEMPERATURES ACROSS THE NORTHERN HALVES OF THE EASTERN
ROCKIES AND PLAINS, AS WELL AS THE UPPER MIDWEST. SOUTHERLY FLOW FARTHER EAST
CONTINUES TO FAVOR ABOVE-NORMAL TEMPERATURES FROM THE MISSISSIPPI VALLEY TO THE
ATLANTIC COAST.
THE 500-HPA TROUGH, CENTERED OVER THE MISSISSIPPI VALLEY, CONTINUES TO FAVOR
ABOVE NORMAL PRECIPITATION THROUGHOUT A MAJORITY OF THE CENTRAL AND EASTERN
CONUS. BASED ON THE GEFS AND ECMWF REFORECAST TOOLS, THE UNCALIBRATED GEFS, AND
THE ANALOG TOOL DERIVED FROM THE MANUAL 500-HPA HEIGHT BLEND, THE WEEK-2
OUTLOOK LEANS ELEVATED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FOR FLORIDA
AS WELL. MOST GUIDANCE POINTS TOWARD A SIMILAR SMALL INCREASE IN THE ODDS FOR
ABOVE NORMAL RAINFALL IN THE LOWER MISSISSIPPI VALLEY AND MUCH OF TEXAS, BUT
MOST GUIDANCE HAS OVERESTIMATED PRECIPITATION IN THIS REGION RECENTLY, AND NO
TILT OF THE ODDS TOWARD WETTER OR DRIER THAN NORMAL CONDITIONS IS INDICATED IN
THESE REGIONS. THERE ALSO CONTINUES TO BE AN INCREASED POTENTIAL FOR EASTERLY
WAVES TO TRACK FROM THE CARIBBEAN OR WESTERN ATLANTIC NORTHWESTWARD TO THE EAST
COAST OR GULF OF MEXICO, ALTHOUGH NO SPECIFIC TROPICAL DISTURBANCE HAS BEEN
IDENTIFIED AT THIS TIME. THE 500-HPA RIDGE AXIS IN THE WEST IS FORECAST TO
SLIGHTLY SHIFT NORTHWARD LATER IN WEEK-2 WHICH MAY EVENTUALLY LEAD TO ENHANCED
MONSOON FLOW INTO THE SOUTHWEST. THEREFORE, PROBABILITIES FOR BELOW NORMAL
PRECIPITATION ACROSS THIS REGION ARE REDUCED COMPARED TO THE 6-10 DAY PERIOD,
BUT THE STRONG RIDGE ALOFT SUPPORTS INCREASED BELOW-NORMAL PRECIPITATION
PROBABILITIES FOR THE PACIFIC NORTHWEST AND INTERMOUNTAIN WEST.
WITH THE MID-LEVEL RIDGE EXPANDING NORTHWARD FROM THE PACIFIC NORTHWEST TOWARD
NORTHWESTERN NORTH AMERICA, AND THE MID-LEVEL TROUGH WEAKENING SLIGHTLY FARTHER
WEST NEAR THE ALEUTIANS, THE PREVAILING WEATHER ACROSS ALASKA IS UNCERTAIN
GIVEN THE CHANGING PATTERN AND THE MEAN SURFACE FLOW WHICH SHOULD START COMING
FROM A MORE WESTERLY DIRECTION, RATHER THAN FROM THE SOUTH. THIS LEADS TO ODDS
ONLY SLIGHTLY ENHANCED RELATIVE TO CLIMATOLOGY, BUT COULD PORTEND WARMING AND
EVENTUAL DRYING ACROSS SOUTHEASTERN ALASKA.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 30% OF TODAY'S GFS
SUPERENSEMBLE MEAN CENTERED ON DAY 11, 30% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 40% 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
MODEL AGREEMENT AND CONTINUITY ON THE LONGWAVE PATTERN, BUT CONTINUED
INCONSISTENCY AMONG THE TOOLS FORECASTING SENSIBLE WEATHER.
FORECASTER: RICH TINKER
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
AUGUST 17.
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:
19540808 - 20090718 - 19740730 - 19980803 - 19960722
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:
20090717 - 19540807 - 19740729 - 19960726 - 19540802
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 13 - 17 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A N
SRN CALIF A N IDAHO A B NEVADA A B
W MONTANA A B E MONTANA B N WYOMING N N
UTAH A B ARIZONA A B COLORADO N N
NEW MEXICO A N N DAKOTA B N S DAKOTA B N
NEBRASKA B A KANSAS N A OKLAHOMA A A
N TEXAS A N S TEXAS A N W TEXAS A N
MINNESOTA B A IOWA B A MISSOURI N A
ARKANSAS A A LOUISIANA A N WISCONSIN B A
ILLINOIS N A MISSISSIPPI A N MICHIGAN B A
INDIANA N A OHIO N A KENTUCKY N A
TENNESSEE A A 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 A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A A GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE A N
AK ALEUTIAN B N AK WESTERN B A AK INT BSN A A
AK S INT B A AK SO COAST B A AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 15 - 21 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A N NRN CALIF A N
SRN CALIF A N IDAHO A N NEVADA A N
W MONTANA N N E MONTANA B N WYOMING B N
UTAH A N ARIZONA A N COLORADO A N
NEW MEXICO A N N DAKOTA B N S DAKOTA B N
NEBRASKA N N KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS A N W TEXAS A N
MINNESOTA B N IOWA N N MISSOURI A N
ARKANSAS A N LOUISIANA A N WISCONSIN A A
ILLINOIS A N MISSISSIPPI A N MICHIGAN A N
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A N ALABAMA A N NEW YORK A A
VERMONT A A 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 A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE N A
AK ALEUTIAN N N AK WESTERN N N AK INT BSN N A
AK S INT N A AK SO COAST N A AK PNHDL N B
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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