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FXUS06 KWBC 211902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE MAY 21 2024
6-10 DAY OUTLOOK FOR MAY 27 - 31 2024
DYNAMICAL MODELS ARE IN GOOD AGREEMENT REGARDING THE 500-HPA HEIGHT PATTERN
ACROSS NORTH AMERICA DURING THE 6-10 DAY PERIOD. A POTENT TROUGH IS FORECAST TO
MOVE ACROSS THE EASTERN U.S. OVER THE COURSE OF THE PERIOD, WITH MODELS MORE
AMPLIFIED WITH THIS FEATURE COMPARED TO YESTERDAY. UPSTREAM, ANOMALOUS RIDGING
IS PREDICTED TO BUILD OVER THE WESTERN AND CENTRAL CONUS. AN AREA OF TROUGHING
MAY SHIFT FROM THE GULF OF ALASKA TOWARD THE WEST COAST, BUT MODELS DIFFER IN
ITS AMPLITUDE. THE 0Z ECMWF ENSEMBLE WEAKENS THE TROUGH, WHILE THE 0Z GEFS AND
CANADIAN ENSEMBLES MAINTAIN WEAK NEGATIVE HEIGHT ANOMALIES AS THE TROUGH
APPROACHES THE WEST COAST LATER IN THE PERIOD. INITIALLY, RIDGING IS FORECAST
OVER THE CENTRAL PACIFIC, EXTENDING THROUGH THE ALEUTIANS AND BERING SEA, BUT
THIS FEATURE IS FORECAST TO WEAKEN BY THE MIDDLE OF THE PERIOD WITH MORE
TROUGHING DEVELOPING OVER THE BERING SEA. TODAY’S MANUAL 500-HPA HEIGHT BLEND
DEPICTS NEAR- TO BELOW-NORMAL HEIGHTS FOR MOST OF THE EASTERN CONUS, EXCLUDING
PARTS OF FLORIDA AND MAINE WHERE ABOVE-NORMAL HEIGHTS ARE PREDICTED DOWNSTREAM
OF THE INCOMING TROUGH. ABOVE-NORMAL HEIGHTS ARE FAVORED FOR MUCH OF THE
WESTERN HALF OF THE CONUS, ALONG WITH SOUTHWESTERN AND NORTHWESTERN ALASKA.
NEAR- TO BELOW-NORMAL HEIGHTS ARE FORECAST ACROSS THE HAWAIIAN ISLANDS.
GIVEN THE STRONGER TROUGHING BEING MODELED ACROSS THE EAST, REFORECAST AND
UNCALIBRATED TOOLS HAVE INCREASED BELOW-NORMAL TEMPERATURE PROBABILITIES
COMPARED TO YESTERDAY ACROSS THE MIDWEST AND THIS IS REFLECTED IN TODAY’S
OUTLOOK. NEAR-NORMAL TEMPERATURES ARE HIGHLIGHTED FURTHER EAST DUE IN PART TO
THE HIGHER PROBABILITIES OF ABOVE-NORMAL TEMPERATURES IN YESTERDAY’S OUTLOOK.
ENHANCED PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES ARE FAVORED ACROSS
NORTHERN NEW ENGLAND AND CLOSER TO THE GULF COAST AND SOUTHEAST, FURTHER
DISPLACED FROM THE TROUGH AND CONSISTENT WITH THE GEFS AND ECMWF REFORECAST
TOOLS. INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE FAVORED OVER MUCH OF
THE WEST DUE TO PREDICTED RIDGING, WITH NEAR-TO BELOW-NORMAL TEMPERATURES
FAVORED ALONG THE WEST COAST DUE TO THE INFLUENCE FROM POTENTIAL TROUGHING
UPSTREAM. ABOVE-NORMAL TEMPERATURE CHANCES ARE INCREASED OVER PARTS OF
NORTHWESTERN MAINLAND ALASKA, WHILE BELOW-NORMAL TEMPERATURE PROBABILITIES ARE
INCREASED OVER MUCH OF SOUTHERN ALASKA, INCLUDING PARTS OF THE ALEUITANS AND
SOUTHEAST ALASKA. NEAR- TO BELOW-NORMAL TEMPERATURE PROBABILITIES ARE FAVORED
ACROSS HAWAII UNDERNEATH WEAK TROUGHING.
ABOVE-NORMAL PRECIPITATION PROBABILITIES ARE INCREASED OVER THE SOUTH-CENTRAL
AND EASTERN CONUS DUE TO AMPLIFYING TROUGHING RESULTING IN A SURFACE LOW AND
ASSOCIATED FRONTAL SYSTEM TRACKING THROUGH THE REGION EARLY IN THE PERIOD,
POSSIBLY LINGERING ACROSS THE NORTHEAST. IN CONTRAST, INCREASED RIDGING FAVORS
BELOW-NORMAL PRECIPITATION OVER MUCH OF THE WESTERN AND NORTH-CENTRAL CONUS,
EXCEPT FOR PORTIONS OF THE PACIFIC NORTHWEST WHERE ABOVE-NORMAL PRECIPITATION
IS INDICATED DUE TO A POTENTIAL TROUGH APPROACHING THE WEST COAST. ABOVE-NORMAL
PRECIPITATION CHANCES ARE ELEVATED OVER MOST OF ALASKA DUE TO THE TREND TOWARD
MORE TROUGHING OVER THE BERING SEA LATE IN THE PERIOD AND SUPPORTED BY MOST OF
THE DYNAMICAL PRECIPITATION FORECAST TOOLS. IN HAWAII, ABOVE-NORMAL
PRECIPITATION PROBABILITIES ARE INCREASED DUE TO TROUGHING.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF TODAY'S OPERATIONAL 6Z GFS CENTERED ON
DAY 8, 30% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF
TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8, AND 30% 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, DUE TO
GOOD AGREEMENT AMONG THE FORECAST TOOLS, OFFSET BY SOME CHANGES COMPARED TO
YESTERDAY RELATED TO MORE AMPLIFIED TROUGHING IN THE EAST.
8-14 DAY OUTLOOK FOR MAY 29 - JUN 04, 2024
DURING WEEK-2, THE TROUGHING PREDICTED ACROSS THE EAST IS FORECAST TO GRADUALLY
WEAKEN AND LIFT OUT. RIDGING IS INITIALLY FAVORED ACROSS THE WESTERN AND
CENTRAL CONUS, BUT THE AMPLITUDE IS FAVORED TO DECREASE LATER IN THE PERIOD. AS
THE AFOREMENTIONED TROUGH WEAKENS AND UPSTREAM RIDGING EXPANDS EASTWARD,
POSITIVE HEIGHT ANOMALIES MAY BUILD OVER PARTS OF THE EAST BY THE END OF THE
PERIOD, BUT THIS IS DEPENDENT ON THE AMPLITUDE OF THE RIDGE. THE CANADIAN
ENSEMBLE IS THE MOST ROBUST WITH THIS POTENTIAL, WITH THE 0Z ECMWF AND GEFS
MAINTAINING A MORE ZONAL FLOW PATTERN ACROSS THE EAST, WITH SOME HINTS OF
TROUGHING REMAINING. TROUGHING IS FORECAST TO BUILD ACROSS THE BERING SEA AND
SOUTHWESTERN ALASKA, WITH RIDGING UPSTREAM OVER EASTERN AND SOUTHEAST ALASKA.
THE WEEK-2 MANUAL 500-HPA HEIGHT BLEND DEPICTS NEAR- TO SLIGHTLY BELOW-NORMAL
HEIGHTS OVER PARTS OF THE EAST AND ABOVE-NORMAL 500-HPA HEIGHTS ACROSS THE
CENTRAL AND WESTERN CONUS ALONG WITH NORTHERN NEW ENGLAND. NEAR-NORMAL HEIGHTS
ARE FORECAST OVER MUCH OF ALASKA AND HAWAII.
TROUGHING IS FORECAST ACROSS THE EAST EARLY IN THE WEEK-2 PERIOD, FAVORING
ENHANCED CHANCES FOR BELOW-NORMAL TEMPERATURES TO CLOSE OUT MAY. WHILE
TEMPERATURES COULD BEGIN TO REBOUND TOWARD THE END OF WEEK-2, BELOW-NORMAL
TEMPERATURES ARE FAVORED FOR THE PERIOD AS A WHOLE ACROSS THE MIDDLE
MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS AND EXTENDING INTO THE MID-ATLANTIC
AND PARTS OF THE NORTHEAST AND SOUTHEAST. ABOVE-NORMAL TEMPERATURE CHANCES ARE
INCREASED OVER THE GULF COAST, FLORIDA, AND NORTHERN NEW ENGLAND, FURTHER
DISPLACED FROM THE TROUGHING AND UNDERNEATH WEAKER MID-LEVEL HEIGHT ANOMALIES.
RIDGING UPSTREAM FAVORS INCREASED CHANCES FOR ABOVE-NORMAL TEMPERATURES ACROSS
MUCH OF THE INTERIOR WEST, GREAT PLAINS, AND UPPER MISSISSIPPI VALLEY.
BELOW-NORMAL TEMPERATURE CHANCES ARE INCREASED OVER SOUTHERN PORTIONS OF
ALASKA, WITH ABOVE-NORMAL TEMPERATURE CHANCES ENHANCED OVER NORTHERN PARTS OF
THE STATE. OVER HAWAII, SLIGHT TILTS TOWARD ENHANCED ABOVE- (BELOW-) NORMAL
TEMPERATURE PROBABILITIES ARE INDICATED ACROSS THE BIG ISLAND (KAUAI) .
ENHANCED CHANCES FOR ABOVE-NORMAL PRECIPITATION ARE FAVORED FOR THE NORTHEAST
AS TROUGHING AND ASSOCIATED SURFACE LOW PRESSURE LINGER ACROSS THE REGION EARLY
IN THE PERIOD. UPSTREAM OF THE TROUGH, NORTHERLY MID-LEVEL FLOW FAVORS
INCREASING CHANCES FOR BELOW-NORMAL PRECIPITATION ACROSS MUCH OF THE MIDWEST,
EXTENDING INTO PARTS OF THE TENNESSEE VALLEY AND SOUTHEAST, SUPPORTED BY THE
UNCALIBRATED 0Z ECMWF AND CANADIAN ENSEMBLES AND ANALOG GUIDANCE. ENHANCED
CHANCES FOR ABOVE-NORMAL PRECIPITATION ARE FORECAST ACROSS THE SOUTHERN HIGH
PLAINS TIED TO INCREASING CHANCES FOR CONVECTION AND A LOWER PRECIPITATION
CLIMATOLOGY. POSITIVE MID-LEVEL HEIGHT ANOMALIES FAVOR A SLIGHT TILT TOWARD
ELEVATED BELOW-NORMAL PRECIPITATION PROBABILITIES ACROSS THE INTERIOR WEST,
WITH INCREASING ONSHORE FLOW LEADING TO SLIGHTLY ABOVE-NORMAL PRECIPITATION
CHANCES ALONG THE WEST COAST. TROUGHING FAVORED ACROSS THE BERING SEA FAVORS
ENHANCED CHANCES FOR ABOVE-NORMAL PRECIPITATION ACROSS MOST OF ALASKA.
NEAR-NORMAL PRECIPITATION IS PREDICTED ACROSS HAWAII.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 40% 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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
CONTINUED GOOD AGREEMENT AMONG THE FORECAST TOOLS, OFFSET BY A LESS AMPLIFIED
PATTERN TOWARD THE END OF THE PERIOD AND SOME DIFFERENCES EMERGING IN THE TOOLS.
FORECASTER: THOMAS COLLOW
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
JUNE 20.
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:
19620602 - 19990601 - 19890518 - 19860511 - 20030506
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:
19990603 - 19890517 - 19620602 - 20030506 - 19640504
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 27 - 31 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A B NRN CALIF A B
SRN CALIF A B IDAHO A B NEVADA A B
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A B ARIZONA A B COLORADO A N
NEW MEXICO A A N DAKOTA A B S DAKOTA B N
NEBRASKA B N KANSAS B A OKLAHOMA N A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA N B IOWA B B MISSOURI B N
ARKANSAS N N LOUISIANA A A WISCONSIN B N
ILLINOIS B N MISSISSIPPI A A MICHIGAN N N
INDIANA B N OHIO N A KENTUCKY N N
TENNESSEE N A ALABAMA N A NEW YORK N A
VERMONT N A NEW HAMP N A MAINE A A
MASS N A CONN N A RHODE IS N A
PENN N A NEW JERSEY N A W VIRGINIA N A
MARYLAND N A DELAWARE N A VIRGINIA N A
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A N AK N SLOPE A N
AK ALEUTIAN B A AK WESTERN N A AK INT BSN N A
AK S INT B A AK SO COAST B A AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 29 - JUN 04, 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A N NRN CALIF N N
SRN CALIF N N IDAHO A N NEVADA A B
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A N ARIZONA A N COLORADO A N
NEW MEXICO A A N DAKOTA A N S DAKOTA A N
NEBRASKA A N KANSAS N A OKLAHOMA N A
N TEXAS A N S TEXAS A N W TEXAS A A
MINNESOTA A B IOWA N B MISSOURI B B
ARKANSAS B N LOUISIANA A N WISCONSIN A B
ILLINOIS B B MISSISSIPPI B N MICHIGAN N B
INDIANA B B OHIO B B KENTUCKY B B
TENNESSEE B B ALABAMA B B NEW YORK N A
VERMONT N A NEW HAMP N A MAINE A A
MASS N A CONN N A RHODE IS N A
PENN B N NEW JERSEY B A W VIRGINIA B N
MARYLAND B N DELAWARE B A VIRGINIA B N
N CAROLINA B N S CAROLINA B N GEORGIA B N
FL PNHDL A N FL PENIN A N AK N SLOPE A N
AK ALEUTIAN B A AK WESTERN N A AK INT BSN A 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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