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FXUS06 KWBC 021902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED OCTOBER 02 2024
6-10 DAY OUTLOOK FOR OCT 08 - 12 2024
DURING EARLY TO MID-OCTOBER, THE GEFS, ECENS, AND CMCE ARE IN GOOD AGREEMENT
THAT AN EXPANSIVE AND ANOMALOUS 500-HPA RIDGE IS THE MAJOR INFLUENCE ON
TEMPERATURES FOR THE WESTERN TWO-THIRDS OF THE CONTIGUOUS U.S. (CONUS). THESE
ENSEMBLE MEAN SOLUTIONS ARE CONSISTENT THAT THE MID-LEVEL RIDGE STRENGTHENS
DURING THE 6-10 DAY PERIOD. THE ANOMALOUS 500-HPA RIDGE SUPPORTS INCREASED
ABOVE-NORMAL TEMPERATURE PROBABILITIES FROM THE WEST COAST EASTWARD TO THE
GREAT PLAINS AND UPPER MISSISSIPPI VALLEY. THE LARGEST PROBABILITIES (MORE THAN
80 PERCENT) ARE FORECAST ACROSS THE NORTHERN AND CENTRAL ROCKIES ALONG WITH THE
NORTHERN AND CENTRAL GREAT PLAINS WHERE 5-DAY TEMPERATURES ARE LIKELY TO
AVERAGE NEAR OR MORE THAN 15 DEGREES F ABOVE-NORMAL. AN AMPLIFIED 500-HPA
TROUGH FAVORS BELOW-NORMAL TEMPERATURES ACROSS MOST OF THE EASTERN CONUS AND
TOOLS HAVE TRENDED MUCH COOLER FOR THE EAST COAST. THE REFORECAST TOOLS SUPPORT
ELEVATED ABOVE-NORMAL TEMPERATURE PROBABILITIES ACROSS THE FLORIDA PENINSULA.
THE ANOMALOUS 500-HPA RIDGE IS LIKELY TO RESULT IN A DRY PATTERN FOR A MAJORITY
OF THE CONUS. ALONG AND TO THE EAST OF THE PREDICTED RIDGE AXIS, BELOW-NORMAL
PRECIPITATION IS FAVORED ACROSS MOST OF THE CENTRAL AND EASTERN CONUS ALONG
WITH THE NORTHERN ROCKIES. ALTHOUGH MODELS HAVE TRENDED TOWARDS DISSIPATING A
POTENTIAL TROPICAL CYCLONE (TC) WHEN IT TRACKS NORTHWESTWARD TOWARDS THE BAJA
PENINSULA, ENHANCED LOW TO MID-LEVEL MOISTURE IS FORECAST TO OVERSPREAD THE
SOUTHWEST AND GREAT BASIN. THE ENSEMBLE MEANS, ESPECIALLY THE GEFS, DEPICT A
SHORTWAVE TROUGH UNDERCUTTING THE DOMINANT MID-LEVEL RIDGE, CENTERED OVER THE
HIGHER LATITUDES OF WEST-CENTRAL NORTH AMERICA. THIS SHORTWAVE TROUGH MAY
EVENTUALLY BE A TRIGGER FOR PRECIPITATION, ALBEIT LIGHT, TO DEVELOP FOR THE
SOUTHWEST AND NEAR NORMAL PRECIPITATION IS FAVORED FOR THIS REGION. A DEEP
TROUGH OVER THE GULF OF ALASKA AND ENHANCED ONSHORE FLOW ELEVATES CHANCES OF
ABOVE-NORMAL PRECIPITATION ALONG MUCH OF THE WEST COAST.
ACCORDING TO THE NATIONAL HURRICANE CENTER AT 2PM EDT ON OCTOBER 2, THERE IS A
40 PERCENT CHANCE OF TROPICAL CYCLONE (TC) DEVELOPMENT OVER THE GULF OF MEXICO
DURING THE NEXT 7 DAYS. THE DETERMINISTIC GFS AND ECMWF MODELS ALONG WITH THEIR
ENSEMBLE MEMBERS HAVE TRENDED SOUTH WITH THE TRACK OF THIS POTENTIAL TC, DUE TO
SURFACE HIGH PRESSURE SHIFTING SOUTH ACROSS THE OHIO AND TENNESSEE VALLEYS.
COMPARED TO PREVIOUS DAYS, THE INCREASED ABOVE-NORMAL PRECIPITATION
PROBABILITIES ARE REDUCED IN COVERAGE ACROSS THE SOUTHEAST AND ARE NOW LIMITED
MOSTLY TO FLORIDA. THE MODEL SOLUTIONS HAVE A SHARP CUTOFF IN THE PRECIPITATION
AMOUNTS FARTHER TO THE NORTH WITH BELOW-NORMAL PRECIPITATION FAVORED FOR THE
SOUTHERN APPALACHIANS AND TENNESSEE VALLEY. ON DAYS 6 AND 7, THE GEFS AND ECENS
HAVE A LOW PRESSURE SYSTEM ACROSS NOVA SCOTIA WHICH ELEVATES CHANCES OF
ABOVE-NORMAL PRECIPITATION FOR MAINE.
THE GEFS, ECENS, AND CMCE AGREE WITH AN AMPLIFIED TROUGH OVER ALASKA WHICH
LEADS TO INCREASED ABOVE-NORMAL PRECIPITATION PROBABILITIES FOR SOUTHEASTERN
PARTS OF THE STATE. DOWNSLOPE SURFACE FLOW RESULTS IN ELEVATED BELOW-NORMAL
PRECIPITATION PROBABILITIES ACROSS NORTHERN MAINLAND ALASKA, WHILE AN OFFSHORE
SURFACE LOW FAVORS BELOW-NORMAL PRECIPITATION THROUGHOUT MUCH OF WESTERN
MAINLAND ALASKA. THE GEFS AND ECMWF REFORECAST TOOLS SUPPORT INCREASED CHANCES
OF ABOVE-NORMAL TEMPERATURES ACROSS NORTHEASTERN MAINLAND ALASKA. THE ELEVATED
BELOW-NORMAL TEMPERATURE PROBABILITIES FORECAST FOR COASTAL WESTERN ALASKA AND
THE ALEUTIANS ARE RELATED TO BELOW-NORMAL SEA SURFACE TEMPERATURES.
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: FORECAST CONFIDENCE: ABOVE
AVERAGE, 4 OUT OF 5, DUE TO GOOD MODEL AGREEMENT ON ANOMALOUS RIDGING AND ITS
EFFECTS ON TEMPERATURE AND PRECIPITATION FOR A MAJORITY OF THE CONUS.
8-14 DAY OUTLOOK FOR OCT 10 - 16 2024
THE GEFS, ECENS, AND CMCE MAINTAIN THE ANOMALOUS 500-HPA RIDGE OVER THE
WEST-CENTRAL CONUS THROUGH WEEK-2. THESE ENSEMBLE MEAN SOLUTIONS DEPICT THE
RIDGE PEAKING IN STRENGTH ON DAY 11 (OCTOBER 13) WHEN 500-HPA HEIGHT DEPARTURES
EXCEED 180 METERS ACROSS MONTANA AND NORTH DAKOTA. STRONGLY ENHANCED
ABOVE-NORMAL TEMPERATURE PROBABILITIES ARE FORECAST 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.
TELECONNECTIONS UPON THE LARGE POSITIVE 500-HPA HEIGHT ANOMALY CENTERED OVER
MANITOBA FAVORS BELOW-NORMAL TEMPERATURES ACROSS THE EASTERN CONUS. ANOTHER
FACTOR THAT SUPPORTS LEANING TOWARDS BELOW-NORMAL TEMPERATURES FOR THIS REGION
IS THE PERSISTENCE OF A NEGATIVE PHASE OF THE NORTH ATLANTIC OSCILLATION
THROUGH AT LEAST EARLY WEEK-2. THEREFORE, THE WEEK-2 OUTLOOK LEANS TOWARDS
BELOW-NORMAL TEMPERATURES FROM THE APPALACHIANS TO THE EAST COAST.
DUE TO THE BROAD AND AMPLIFIED 500-HPA RIDGE, A DRY PATTERN IS LIKELY TO
PERSIST FOR A MAJORITY OF THE CONUS THROUGH MID-OCTOBER. ANY TC THAT FORMS IN
THE GULF OF MEXICO BY EARLY NEXT WEEK IS EXPECTED TO MOVE SLOWLY EAST WHICH
ELEVATES ABOVE-NORMAL PRECIPITATION PROBABILITIES FOR THE FLORIDA PENINSULA.
ENHANCED LOW TO MID-LEVEL MOISTURE FROM THE EAST PACIFIC COUPLED WITH A
SHORTWAVE TROUGH LEADS TO SLIGHTLY ELEVATED ABOVE-NORMAL PRECIPITATION
PROBABILITIES ACROSS THE FOUR CORNERS REGION. EARLY IN WEEK-2, THE ENSEMBLE
MEAN SOLUTIONS DEPICT A RETROGRESSION OF THE AMPLIFIED TROUGH OVER THE GULF OF
ALASKA AND THE ANOMALOUS MID-LEVEL RIDGE OVER THE CENTRAL CONUS EXPANDING
WESTWARD. BASED ON THIS EVOLVING LONGWAVE PATTERN, THE 8-14 DAY OUTLOOK IS
DRIER THAN THE 6-10 DAY OUTLOOK ALONG THE WEST COAST.
AN AMPLIFIED 500-HPA TROUGH AND ENHANCED ONSHORE FLOW FAVOR ABOVE-NORMAL
PRECIPITATION ACROSS SOUTHEASTERN 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 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: FORECAST CONFIDENCE: ABOVE
AVERAGE, 4 OUT OF 5, DUE TO EXCELLENT AGREEMENT AMONG THE TEMPERATURE TOOLS
WITH THE HIGHEST UNCERTAINTY IN THE PRECIPITATION OUTLOOK FOR THE SOUTHWEST.
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:
20051014 - 19600923 - 19640921 - 20080925 - 20030921
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:
20051014 - 19600923 - 20030920 - 20030913 - 19640920
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 08 - 12 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A N IDAHO A B 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 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 N B WISCONSIN A B
ILLINOIS A B MISSISSIPPI N B MICHIGAN A B
INDIANA N B OHIO B B KENTUCKY B B
TENNESSEE B B ALABAMA N B NEW YORK B B
VERMONT B B NEW HAMP B B MAINE B A
MASS B B CONN B B RHODE IS B B
PENN B B NEW JERSEY B B W VIRGINIA B B
MARYLAND B B DELAWARE B B VIRGINIA B B
N CAROLINA B B S CAROLINA B B GEORGIA B N
FL PNHDL N A FL PENIN A A AK N SLOPE A B
AK ALEUTIAN B N AK WESTERN N B AK INT BSN A B
AK S INT N A AK SO COAST N A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 10 - 16 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 N
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A N 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 N B KENTUCKY N B
TENNESSEE N B ALABAMA N B NEW YORK B B
VERMONT B B NEW HAMP B B MAINE B N
MASS B B CONN B B RHODE IS B B
PENN B B NEW JERSEY B B W VIRGINIA B B
MARYLAND B B DELAWARE B B VIRGINIA B B
N CAROLINA B B S CAROLINA B B GEORGIA B B
FL PNHDL B A FL PENIN B A AK N SLOPE A N
AK ALEUTIAN B N AK WESTERN N N AK INT BSN A N
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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