542
FXUS06 KWBC 041902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI OCTOBER 04 2024
6-10 DAY OUTLOOK FOR OCT 10 - 14 2024
A BROAD AND ANOMALOUS 500-HPA RIDGE OVER THE NORTH-CENTRAL CONTIGUOUS U.S.
(CONUS) IS FORECAST TO BE THE MAJOR INFLUENCE ON THE 6-10 DAY TEMPERATURE AND
PRECIPITATION OUTLOOK. THE GEFS, ECENS, AND CMCE ARE IN GOOD AGREEMENT AND
CONSISTENT THAT THIS MID-LEVEL RIDGE STRENGTHENS DURING THE 6-10 DAY PERIOD AND
REACHES ITS PEAK MAGNITUDE (500-HPA HEIGHT DEPARTURES OF MORE THAN 180 METERS)
ON OCTOBER 13. THE ANOMALOUS 500-HPA RIDGE SUPPORTS INCREASED ABOVE-NORMAL
TEMPERATURE PROBABILITIES FROM THE WEST COAST EASTWARD TO THE GREAT PLAINS AND
MIDWEST. THE LARGEST PROBABILITIES (MORE THAN 80 PERCENT) ARE FORECAST ACROSS
THE UPPER MISSISSIPPI VALLEY, NORTHERN TO CENTRAL GREAT PLAINS, AND INTERIOR
WEST WHERE 5-DAY TEMPERATURES ARE LIKELY TO AVERAGE NEAR OR MORE THAN 15
DEGREES F ABOVE-NORMAL. AN AMPLIFIED 500-HPA TROUGH NEARBY OVER THE
NORTHWESTERN ATLANTIC FAVORS BELOW-NORMAL TEMPERATURES ALONG MUCH OF THE EAST
COAST.
ALONG AND TO THE EAST OF THE PREDICTED RIDGE AXIS, INCREASED BELOW-NORMAL
PRECIPITATION PROBABILITIES ARE FORECAST ACROSS MOST OF THE CENTRAL AND EASTERN
CONUS ALONG WITH THE NORTHERN ROCKIES. ACCORDING TO THE NATIONAL HURRICANE
CENTER AT 2PM EDT ON OCTOBER 4, THERE IS A 50 PERCENT CHANCE OF TROPICAL
CYCLONE (TC) DEVELOPMENT OVER THE GULF OF MEXICO DURING THE NEXT 7 DAYS. BY
DAY 7 (OCTOBER 11), MODEL CONSENSUS DEPICTS EITHER A TC, SUBTROPICAL LOW, OR
LOW PRESSURE SYSTEM ALONG A FRONT OVER SOUTH FLORIDA OR THE BAHAMAS. THEREFORE,
ABOVE-NORMAL PRECIPITATION REMAINS PROBABLE FOR THE FLORIDA PENINSULA. A
SHORTWAVE TROUGH, UNDERCUTTING THE DOMINANT MID-LEVEL RIDGE CENTERED OVER THE
HIGHER LATITUDES OF CENTRAL NORTH AMERICA, MAY INTERACT WITH ENHANCED LOW TO
MID-LEVEL MOISTURE AND RESULT IN LIGHT PRECIPITATION ACROSS THE FOUR CORNERS
REGION. NEAR TO ABOVE-NORMAL PRECIPITATION IS FAVORED FOR THE FOUR CORNERS
REGION ALONG WITH THE WEST COAST, WHICH IS SUPPORTED BY THE CONSOLIDATION TOOL
(SKILL-WEIGHTED GEFS AND ECMWF REFORECASTS).
THE GEFS, ECENS, AND CMCE AGREE WITH AN AMPLIFIED TROUGH OVER THE GULF OF
ALASKA WITH ENHANCED ONSHORE FLOW AFFECTING SOUTHEASTERN ALASKA. BASED ON THIS
FLOW PATTERN AND SUPPORT FROM MODEL GUIDANCE, ABOVE-NORMAL PRECIPITATION
PROBABILITIES EXCEED 50 PERCENT FOR SOUTHEASTERN ALASKA. OFFSHORE SURFACE FLOW
FAVORS BELOW-NORMAL PRECIPITATION THROUGHOUT MUCH OF WESTERN MAINLAND ALASKA.
THE GEFS AND ECMWF REFORECAST TOOLS SUPPORT INCREASED CHANCES OF ABOVE-NORMAL
TEMPERATURES ACROSS EASTERN MAINLAND ALASKA. THE ELEVATED BELOW-NORMAL
TEMPERATURE PROBABILITIES FORECAST FOR COASTAL WESTERN ALASKA AND THE ALEUTIANS
ARE RELATED TO BELOW-NORMAL SEA SURFACE TEMPERATURES AND NORTHEASTERLY SURFACE
FLOW.
BASED ON THE GEFS AND ECENS, ABOVE-NORMAL TEMPERATURES AND NEAR NORMAL
PRECIPITATION ARE FAVORED FOR HAWAII.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 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 30% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY
8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: MUCH ABOVE AVERAGE, 5 OUT OF 5,
DUE TO EXCELLENT MODEL AGREEMENT ON ANOMALOUS RIDGING AND ITS EFFECTS ON
TEMPERATURE AND PRECIPITATION FOR A MAJORITY OF THE CONUS.
8-14 DAY OUTLOOK FOR OCT 12 - 18 2024
THE GEFS, ECENS, AND CMCE ARE IN GOOD AGREEMENT ON AN AMPLIFIED 500-HPA PATTERN
THROUGH EARLY WEEK-2 AND THOSE MODEL SOLUTIONS FEATURE A TROUGH OVER THE NORTH
PACIFIC, A RIDGE CENTERED ACROSS THE NORTH-CENTRAL CONUS, AND A TROUGH OVER THE
NORTHWESTERN ATLANTIC. LATER IN WEEK-2, THE NORTHWESTERN ATLANTIC TROUGH IS
FORECAST TO SHIFT EASTWARD WITH RISING 500-HPA HEIGHTS ALONG THE EAST COAST.
ALSO, THE LONGWAVE PATTERN OVER NORTH AMERICA AND THE NORTH PACIFIC IS FORECAST
TO BECOME LESS AMPLIFIED BY THE END OF WEEK-2.
THE AMPLIFIED RIDGE AND LARGE POSITIVE 500-HPA HEIGHT DEPARTURES RESULT IN
STRONGLY ENHANCED ABOVE-NORMAL TEMPERATURE PROBABILITIES THROUGHOUT THE WESTERN
AND CENTRAL CONUS. PROBABILITIES EXCEED 80 PERCENT ACROSS THE NORTHERN GREAT
PLAINS GIVEN THE EXCELLENT MODEL AGREEMENT ON THE HIGHLY AMPLIFIED RIDGE
PEAKING IN STRENGTH EARLY IN WEEK-2. TEMPERATURES ARE EXPECTED TO BE VARIABLE
DURING THE 8-14 DAY PERIOD ALONG THE EAST COAST, STARTING OUT ON THE COOLER
SIDE AND THEN TRENDING TO NEAR OR EVEN SLIGHTLY ABOVE NORMAL. AVERAGED OVER A
7-DAY PERIOD, NEAR NORMAL TEMPERATURES ARE FAVORED FOR MOST AREAS FROM THE
APPALACHIANS TO THE EAST COAST. BASED ON THE CONSOLIDATION AND ANALOG TOOLS, A
SLIGHT TILT TOWARDS BELOW-NORMAL TEMPERATURE IS FORECAST FOR PORTIONS OF THE
COASTAL SOUTHEAST.
DUE TO THE BROAD AND AMPLIFIED 500-HPA RIDGE ALONG WITH THE ABSENCE OF ANY
MOIST INFLOW FROM THE GULF OF MEXICO THROUGH MUCH OF WEEK-2, A DRY PATTERN IS
LIKELY FOR NEARLY ALL OF THE CENTRAL AND EASTERN CONUS. THE ONE EXCEPTION IS
THE FLORIDA PENINSULA WHERE A POTENTIAL TC AND/OR STATIONARY FRONT FAVORS
ABOVE-NORMAL PRECIPITATION. ALTHOUGH BELOW-NORMAL PRECIPITATION PROBABILITIES
REMAIN RELATIVELY LARGE (ABOVE 50 PERCENT) ACROSS THE EASTERN GREAT PLAINS AND
MIDDLE MISSISSIPPI VALLEY, UNCERTAINTY MAY INCREASE IN SUBSEQUENT OUTLOOKS AS
THE FLOW BECOMES LESS AMPLIFIED WITH TIME. SINCE MODEL GUIDANCE HAS TRENDED
TOWARDS HIGHER 500-HPA HEIGHTS ACROSS THE SOUTHWEST AND THERE ARE CONFLICTING
SIGNALS AMONG THE PRECIPITATION TOOLS, NEAR NORMAL PRECIPITATION IS FAVORED FOR
THE SOUTHWEST. THE CONSOLIDATION AND UNCALIBRATED MODEL TOOLS SUPPORT ELEVATED
BELOW-NORMAL PRECIPITATION PROBABILITIES ACROSS THE PACIFIC NORTHWEST.
AN AMPLIFIED 500-HPA TROUGH AND ENHANCED ONSHORE FLOW FAVOR ABOVE-NORMAL
PRECIPITATION ACROSS EASTERN MAINLAND ALASKA AND SOUTHEASTERN ALASKA, WHILE
OFFSHORE SURFACE FLOW TILTS THE OUTLOOK TOWARDS BELOW-NORMAL PRECIPITATION FOR
WESTERN MAINLAND ALASKA. MODEL GUIDANCE REMAINS CONSISTENT AND IN GOOD
AGREEMENT WITH INCREASED ABOVE (BELOW)-NORMAL TEMPERATURE PROBABILITIES FOR
EASTERN AND CENTRAL MAINLAND ALASKA (COASTAL WESTERN ALASKA AND THE ALEUTIANS).
BASED ON THE GEFS AND ECENS, INCREASED CHANCES OF ABOVE-NORMAL TEMPERATURES ARE
FORECAST FOR HAWAII. NEAR TO ABOVE-NORMAL PRECIPITATION IS FAVORED FOR MUCH OF
THE STATE.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 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 30% 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
GOOD AGREEMENT AMONG THE TEMPERATURE AND PRECIPITATION TOOLS BUT SIGNS OF
INCREASING FORECAST UNCERTAINTY BY THE END OF WEEK-2.
FORECASTER: BRAD PUGH
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
OCTOBER 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:
19550929 - 19600924 - 20050918 - 20071001 - 19901010
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:
19550929 - 20050918 - 19600924 - 20070930 - 20041005
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 10 - 14 2024
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 A B WYOMING A B
UTAH A B ARIZONA A N COLORADO A B
NEW MEXICO A B N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA A B WISCONSIN A B
ILLINOIS A B MISSISSIPPI N B MICHIGAN A B
INDIANA A B OHIO A B KENTUCKY A B
TENNESSEE N B ALABAMA N B NEW YORK B B
VERMONT B B NEW HAMP B B MAINE B B
MASS B B CONN B B RHODE IS B B
PENN N B NEW JERSEY B B W VIRGINIA N B
MARYLAND B B DELAWARE B B VIRGINIA B B
N CAROLINA B B S CAROLINA B B GEORGIA B B
FL PNHDL B N FL PENIN N A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B B AK INT BSN A N
AK S INT A A AK SO COAST A A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 12 - 18 2024
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 A B WYOMING A B
UTAH A N ARIZONA A N COLORADO A B
NEW MEXICO A B N DAKOTA A B S DAKOTA A B
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA A B IOWA A B MISSOURI A B
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 N B NEW YORK N B
VERMONT N B NEW HAMP N B MAINE N N
MASS N B CONN N B RHODE IS N B
PENN N B NEW JERSEY N B W VIRGINIA N B
MARYLAND N B DELAWARE N B VIRGINIA N B
N CAROLINA N B S CAROLINA N B GEORGIA N B
FL PNHDL N N FL PENIN N A AK N SLOPE A A
AK ALEUTIAN B N AK WESTERN N N AK INT BSN A A
AK S INT A A AK SO COAST A 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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