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FXUS06 KWBC 171903
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED JULY 17 2024
6-10 DAY OUTLOOK FOR JUL 23 - 27 2024
THE MID-LEVEL HEIGHT PATTERN ACROSS NORTH AMERICA AND THE SURROUNDING REGIONS
REMAINS FAIRLY AMPLIFIED FOR THE MIDDLE OF SUMMER, PARTICULARLY EARLY IN THE
PERIOD. A WEAKENING RIDGING IS FORECAST OVER MUCH OF THE WESTERN CONTIGUOUS
U.S. (CONUS) WITH A POSITIVELY TILTED TROUGH ACROSS THE CENTRAL CONUS. ALONG
THE COAST OF SOUTHEAST ALASKA AND BRITISH COLUMBIA, A SHORTWAVE TROUGH IS
FORECAST AND WILL INCREASE ONSHORE FLOW INTO THE PACIFIC NORTHWEST. IN THE
WESTERN ATLANTIC OCEAN, WEAK POSITIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST.
OVER ALASKA, POSITIVE MID-LEVEL HEIGHT ANOMALIES ARE FORECAST WITH WEAK RIDGING
ACROSS MUCH OF THE STATE; HOWEVER, GUIDANCE IS SUGGESTING A PATTERN CHANGE MAY
OCCUR AT THE END OF THE PERIOD. NEAR-NORMAL 500-HPA HEIGHTS ARE FORECAST FOR
HAWAII.
THE 6-10 DAY TEMPERATURE PATTERN HAS A LARGE DIPOLE ACROSS A FAIRLY SHORT
DISTANCE WITH STRONGLY ABOVE-NORMAL TEMPERATURES FAVORED ACROSS THE INTERIOR
WEST AND STRONGLY BELOW NORMAL TEMPERATURES LIKELY IN THE SOUTH-CENTRAL CONUS.
THE ABOVE-NORMAL TEMPERATURES ARE ASSOCIATED WITH MID-LEVEL RIDGING OVER THE
WEST. BELOW-NORMAL TEMPERATURES ARE LIKELY ACROSS THE SOUTH-CENTRAL CONUS AND
ARE ASSOCIATED WITH A POSITIVELY TILTED TROUGH ACROSS THE CENTRAL CONUS. ALONG
THE ATLANTIC SEABOARD, GREAT LAKES, AND NORTHEAST A TILT TOWARDS ABOVE-NORMAL
TEMPERATURES IS FAVORED WITH GUIDANCE COMING INTO BETTER AGREEMENT FOR WARMER
TEMPERATURES TO BECOME BETTER ESTABLISHED BY THE END OF THE PERIOD. THERE
REMAINS SOME DISAGREEMENT IN THE EVOLUTION OF THE MID-LEVEL HEIGHT PATTERN THAT
MAY REDUCE TEMPERATURES, THUS ONLY A SLIGHT TILT TOWARDS ABOVE-NORMAL
TEMPERATURES IS FORECAST. OVER THE FLORIDA PENINSULA, ABOVE-NORMAL TEMPERATURES
ARE MORE STRONGLY FAVORED BENEATH SUBTROPICAL RIDGING AND EAST OF A MEAN
FRONTAL BOUNDARY. A WEAK SHORTWAVE TROUGH IN THE GULF OF ALASKA AND BRITISH
COLUMBIA MAY BRING NEAR TO BELOW-NORMAL TEMPERATURES TO PORTIONS OF THE PACIFIC
NORTHWEST. IN ALASKA, ABOVE-NORMAL TEMPERATURES ARE GENERALLY FAVORED ACROSS
MUCH OF THE MAINLAND. HOWEVER, PROBABILITIES ARE QUITE REDUCED RELATIVE TO
YESTERDAY WITH BETTER AGREEMENT AMONG THE TOOLS FOR A PATTERN CHANGE TO OCCUR
AT THE END OF THE PERIOD. NEAR TO BELOW-NORMAL TEMPERATURES ARE FAVORED IN
SOUTHEAST ALASKA AND THE ALEUTIAN ISLANDS. IN HAWAII, ABOVE-NORMAL TEMPERATURES
ARE FAVORED FOR THE WESTERN PORTIONS OF THE STATE WHILE NEAR-NORMAL
TEMPERATURES ARE FAVORED FURTHER EAST CONSISTENT WITH THE DYNAMICAL TOOLS.
THE 6-10 DAY PRECIPITATION FAVORS ABOVE-NORMAL PRECIPITATION ACROSS MUCH OF THE
EASTERN CONUS AND SOUTHWEST. IN THE SOUTHWEST AND PARTS OF THE INTERIOR WEST,
THERE CONTINUES TO BE INCREASED CHANCES FOR ABOVE-NORMAL PRECIPITATION
ASSOCIATED WITH MONSOON ACTIVITY WITH SURFACE HIGH PRESSURE SITUATED OVER THE
FOUR CORNERS REGION PROMOTING MOISTURE ADVECTION INTO THE REGION. THE SURFACE
HIGH PRESSURE IS WEAKER TODAY RELATIVE TO PRIOR FORECASTS AND THEREFORE,
PROBABILITIES HAVE BEEN REDUCED ACROSS THE SOUTHWEST. FURTHER EAST, A TROUGH
AND ASSOCIATED STALLED FRONTAL SYSTEM INCREASE CHANCES FOR ABOVE-NORMAL
PRECIPITATION FROM TEXAS THROUGH MUCH OF THE EASTERN CONUS. ACROSS THE NORTHERN
PLAINS AND PARTS OF THE NORTHERN ROCKIES, BELOW-NORMAL PRECIPITATION IS FAVORED
BENEATH MID-LEVEL RIDGING. NEAR-NORMAL PRECIPITATION IS LARGELY FAVORED IN THE
WESTERN CONUS WITH WEAK PRECIPITATION SIGNALS IN AREAS THAT ARE GENERALLY
FAIRLY DRY. ONE EXCEPTION IS IN PARTS OF THE PACIFIC NORTHWEST WHERE INCREASED
ONSHORE FLOW MAY HELP TO BRING SOME PRECIPITATION INTO THE REGION. IN ALASKA,
ABOVE-NORMAL PRECIPITATION IS GENERALLY FAVORED ACROSS MUCH OF THE STATE WITH
CONTINUED CHANCES OF UNSETTLED WEATHER. IN HAWAII, NEAR-NORMAL PRECIPITATION IS
FAVORED CONSISTENT WITH WEAK SIGNALS AND MIXED GUIDANCE.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 30% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED
ON DAY 8, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN 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: ABOVE-AVERAGE, 4 OUT OF 5. GOOD
AGREEMENT AMONG THE DYNAMICAL TOOLS IS OFFSET BY DIFFERENCES IN TEMPERATURE AND
PRECIPITATION PATTERNS ACROSS THE EASTERN CONUS.
8-14 DAY OUTLOOK FOR JUL 25 - 31 2024
DURING WEEK-2, A MID-LEVEL RIDGE ACROSS THE WEST IS BREAKING DOWN AS A
SHORTWAVE TROUGH IMPACTS THE REGION. DURING THE PERIOD 500-HPA HEIGHTS RISE
OVER THE EAST AS A MID-LEVEL TROUGH CENTERED OVER THE SOUTH-CENTRAL CONUS FILLS
IN. NEAR-NORMAL 500-HPA HEIGHT ANOMALIES ARE FORECAST ACROSS THE SOUTHERN CONUS
WITH SLIGHTLY BELOW-NORMAL HEIGHTS CENTERED OVER THE SOUTHERN PLAINS. WEAK
TROUGHING IS FORECAST OVER BRITISH COLUMBIA SOUTHWARD TO THE PACIFIC NORTHWEST.
OVERALL, THIS LEAVES NEAR ZONAL FLOW ACROSS THE CONUS FOR THE WEEK-2 MEAN. IN
ALASKA, A BIG PATTERN SHIFT IS OCCURRING FROM THE 6-10 DAY PERIOD INTO THE
WEEK-2. POSITIVE MID-LEVEL HEIGHT ANOMALIES IN THE 6-10 DAY PERIOD, GIVE WAY TO
BELOW-NORMAL HEIGHTS ACROSS MUCH OF ALASKA FOR WEEK-2. THERE IS BETTER
AGREEMENT AMONG THE DYNAMICAL TOOLS FOR THIS PATTERN CHANGE TO TAKE HOLD EARLY
IN THE WEEK-2 PERIOD. THEREFORE, THE WEEK-2 MEAN 500-HPA HEIGHTS FOR MOST OF
ALASKA SHOW NEGATIVE 500-HPA HEIGHT ANOMALIES AND A WEAK TROUGH. OVER THE
ALEUTIAN ISLANDS POSITIVE 500-HPA HEIGHTS ARE FAVORED. IN HAWAII, NEAR-NORMAL
HEIGHTS REMAIN FORECAST FOR THE STATE.
THE WEEK-2 TEMPERATURE OUTLOOK MAINTAINS ELEVATED CHANCES FOR ABOVE-NORMAL
TEMPERATURES ACROSS THE NORTHERN PLAINS STRETCHING BACK THROUGH THE INTERIOR
WEST AND INTO THE FOUR CORNERS BENEATH A MID-LEVEL RIDGE. AS THE PERIOD
PROGRESSES, ABOVE-NORMAL 500-HPA HEIGHTS ARE FORECAST TO DEVELOP IN THE GREAT
LAKES AND MID-ATLANTIC LEADING TO ABOVE-NORMAL TEMPERATURE CHANCES BEING
FAVORED FOR THE WEEK-2 PERIOD ACROSS THESE REGIONS. A TROUGH FORECAST ACROSS
THE CENTRAL CONUS IN THE 6-10 DAY PERIOD, BEGINS TO WASH OUT BY THE MIDDLE TO
END OF WEEK-2. THEREFORE, ELEVATED BELOW-NORMAL TEMPERATURE CHANCES REMAIN BUT
ARE REDUCED RELATIVE TO THE 6-10 DAY PERIOD. STRONGLY ABOVE-NORMAL TEMPERATURE
CHANCES REMAIN FORECAST ACROSS FLORIDA SOUTH OF ANY INTERACTION WITH THE
TROUGH. FOR MAINLAND ALASKA, GUIDANCE IS IN BETTER AGREEMENT FOR A PATTERN
TRANSITION TO OCCUR EARLY IN THE WEEK-2 PERIOD. THEREFORE, THERE IS A
SIGNIFICANT COOLING TREND SEEN RELATIVE TO THE 6-10 DAY PERIOD AND PRIOR
FORECASTS ACROSS THE STATE. HOWEVER, THESE CHANGES ARE JUSTIFIED DUE TO THE
RAPID TRANSITION TO BELOW-NORMAL HEIGHTS AND GOOD AGREEMENT AMONG THE DYNAMICAL
TOOLS FOR BELOW-NORMAL TEMPERATURES TO BECOME ESTABLISHED ACROSS ALASKA DURING
WEEK-2. IN HAWAII, NEAR-NORMAL TEMPERATURES ARE FAVORED WITH WEAK SIGNALS AMONG
THE VARIOUS DYNAMICAL TOOLS.
ABOVE-NORMAL PRECIPITATION REMAINS FAVORED FOR MUCH OF THE AREAS EAST OF THE
MISSISSIPPI RIVER EXTENDING INTO THE SOUTHERN PLAINS. THESE ENHANCED CHANCES
FOR ABOVE-NORMAL PRECIPITATION ARE ASSOCIATED WITH A MID-LEVEL TROUGH AND
ASSOCIATED STALLED FRONTAL BOUNDARY EARLY IN THE WEEK-2 PERIOD. BELOW-NORMAL
PRECIPITATION IS FAVORED IN PORTIONS OF THE NORTHERN AND CENTRAL PLAINS BENEATH
POSITIVE 500-HPA HEIGHT ANOMALIES AND A MID-LEVEL RIDGE. IN THE WESTERN CONUS,
NEAR-NORMAL IS GENERALLY FAVORED. IN THE SOUTHWEST, WEAK SURFACE HIGH PRESSURE
IS FORECAST LEADING TO REDUCED CHANCES FOR MONSOON MOISTURE ADVECTION INTO THE
REGION. THEREFORE, NEAR-NORMAL PRECIPITATION IS FAVORED IN THESE AREAS TODAY.
FURTHER NORTH, NORMAL PRECIPITATION REMAINS LOW FOR THIS TIME OF YEAR AND
FURTHER, THE GUIDANCE IS RELATIVELY MIXED REGARDING PRECIPITATION CHANCES. ONE
EXCEPTION IS IN THE PACIFIC NORTHWEST WHERE A MID-LEVEL SHORTWAVE TROUGH MAY
ENHANCE ONSHORE FLOW AND BRING ABOVE-NORMAL PRECIPITATION CHANCES INTO THE
REGION. IN ALASKA, ABOVE-NORMAL PRECIPITATION REMAINS THE FAVORED OUTCOME
ACROSS THE STATE WITH CONTINUED CHANCES FOR UNSETTLED WEATHER AS FORECAST BY
NEARLY ALL OF THE DYNAMICAL MODEL TOOLS. IN HAWAII, NEAR-NORMAL PRECIPITATION
IS FAVORED CONSISTENT WITH THE TOOLS.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 10% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 30% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED
ON DAY 11, 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 20%
OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: AVERAGE, 3 OUT OF 5, GOOD
AGREEMENT AMONG THE TOOLS OFFSET BY A LESS AMPLIFIED AND TRANSITORY HEIGHT
PATTERN.
FORECASTER: RYAN BOLT
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
JULY 18.
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:
19940721 - 19980706 - 20080630 - 19910731 - 19940707
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:
19940721 - 19980707 - 20080630 - 19910730 - 19590712
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR JUL 23 - 27 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B N OREGON A N NRN CALIF A N
SRN CALIF A N IDAHO A N NEVADA A N
W MONTANA A N E MONTANA A B WYOMING A B
UTAH A N ARIZONA A A COLORADO A N
NEW MEXICO B A N DAKOTA A B S DAKOTA A B
NEBRASKA N N KANSAS B A OKLAHOMA B A
N TEXAS B A S TEXAS B A W TEXAS B A
MINNESOTA A N IOWA N A MISSOURI B A
ARKANSAS B A LOUISIANA B A WISCONSIN A A
ILLINOIS B A MISSISSIPPI B A MICHIGAN A A
INDIANA N A OHIO N A KENTUCKY B A
TENNESSEE B A ALABAMA B A 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 A NEW JERSEY A A W VIRGINIA N A
MARYLAND A A DELAWARE A A VIRGINIA N A
N CAROLINA N A S CAROLINA N A GEORGIA N A
FL PNHDL A A FL PENIN A A AK N SLOPE N A
AK ALEUTIAN B A AK WESTERN N A AK INT BSN A A
AK S INT A A AK SO COAST N N AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR JUL 25 - 31 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON N N NRN CALIF A N
SRN CALIF A N IDAHO A N NEVADA A N
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A N ARIZONA A N COLORADO A N
NEW MEXICO A N N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A N OKLAHOMA B A
N TEXAS B A S TEXAS B A W TEXAS N A
MINNESOTA A N IOWA A A MISSOURI N A
ARKANSAS B A LOUISIANA B A WISCONSIN A A
ILLINOIS N A MISSISSIPPI B A MICHIGAN A A
INDIANA N A OHIO A A KENTUCKY N A
TENNESSEE N A ALABAMA N A NEW YORK A A
VERMONT A N NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS A N
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 A
FL PNHDL A A FL PENIN A N AK N SLOPE B 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 B 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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