497
FXUS06 KWBC 031902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU OCTOBER 03 2024
6-10 DAY OUTLOOK FOR OCT 09 - 13 2024
DURING THE NEXT TWO WEEKS, A BROAD AND ANOMALOUS 500-HPA RIDGE IS FORECAST TO
PERSIST OVER THE NORTH-CENTRAL CONTIGUOUS U.S. (CONUS). 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 UPPER MISSISSIPPI VALLEY. THE LARGEST
PROBABILITIES (MORE THAN 80 PERCENT) ARE FORECAST ACROSS THE NORTHERN AND
CENTRAL GREAT PLAINS ALONG WITH THE ROCKIES WHERE 5-DAY TEMPERATURES ARE LIKELY
TO AVERAGE MORE THAN 15 DEGREES F ABOVE-NORMAL. AN AMPLIFIED 500-HPA TROUGH
FAVORS BELOW-NORMAL TEMPERATURES ACROSS MOST OF THE EASTERN CONUS. THE
REFORECAST TOOLS SUPPORT ELEVATED ABOVE-NORMAL TEMPERATURE PROBABILITIES ACROSS
SOUTH FLORIDA.
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. ACCORDING TO THE NATIONAL HURRICANE CENTER AT 2PM EDT ON OCTOBER 3,
THERE IS A 30 PERCENT CHANCE OF TROPICAL CYCLONE (TC) DEVELOPMENT DURING THE
NEXT 7 DAYS. RECENT MODEL RUNS HAVE TRENDED TOWARDS A FRONTAL WAVE OF LOW
PRESSURE TRACKING SLOWLY EAST FROM THE GULF OF MEXICO TO THE FLORIDA PENINSULA
NEXT WEEK. ABOVE-NORMAL PRECIPITATION REMAINS PROBABLE FOR THE FLORIDA
PENINSULA DUE TO THIS POTENTIAL TC OR WAVE OF LOW PRESSURE. SIMILAR TO PREVIOUS
DAYS, THERE IS LIKELY TO BE A SHARP CUTOFF FROM HEAVY RAINFALL ACROSS THE
FLORIDA PENINSULA TO NO RAINFALL FARTHER TO THE NORTH ACROSS THE SOUTHERN
APPALACHIANS AND TENNESSEE VALLEY. 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. GIVEN THE RELATIVELY DRY
CLIMATOLOGY AT THIS TIME OF YEAR, ELEVATED ABOVE-NORMAL PRECIPITATION
PROBABILITIES ARE FORECAST. A DEEP TROUGH OVER THE GULF OF ALASKA AND ENHANCED
ONSHORE FLOW FAVOR NEAR OR ABOVE-NORMAL PRECIPITATION ALONG THE WEST COAST.
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 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 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 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 11 - 17 2024
THE GEFS, ECENS, AND CMCE ARE IN GOOD AGREEMENT ON AN AMPLIFIED 500-HPA PATTERN
FEATURING A TROUGH OVER THE NORTH PACIFIC, A RIDGE CENTERED ACROSS THE
NORTH-CENTRAL CONUS, AND A TROUGH OVER THE NORTHWESTERN ATLANTIC. 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
ON DAY 10. AN AMPLIFIED 500-HPA NEAR THE EAST COAST COUPLED WITH SURFACE HIGH
PRESSURE SHIFTING SOUTH FROM EASTERN CANADA EARLY IN WEEK-2 FAVOR BELOW-NORMAL
TEMPERATURES FROM THE APPALACHIANS TO THE EAST COAST. BELOW-NORMAL TEMPERATURE
PROBABILITIES ARE LOWER COMPARED TO YESTERDAY AS TEMPERATURES ARE EXPECTED TO
MODERATE LATER IN WEEK-2.
DUE TO THE BROAD AND AMPLIFIED 500-HPA RIDGE ALONG WITH THE ABSENCE OF ANY
MOIST INFLOW FROM THE GULF OF MEXICO, A DRY PATTERN IS LIKELY FOR MUCH 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.
BELOW-NORMAL PRECIPITATION PROBABILITIES EXCEED 60 PERCENT ACROSS THE OZARKS
REGION, MIDDLE MISSISSIPPI VALLEY, AND OHIO VALLEY BASED ON EXCELLENT MODEL
AGREEMENT AND CONSISTENCY AMONG THE REFORECAST TOOLS, UNCALIBRATED MODEL
GUIDANCE, AND ANALOG TOOL DERIVED FROM THE MANUAL 500-HPA HEIGHT BLEND. ONE OR
TWO SHORTWAVE TROUGHS ARE EXPECTED TO UNDERCUT THE DOMINANT MID-LEVEL RIDGE
OVER NORTH AMERICA. THESE SHORTWAVE TROUGHS SUPPORT NEAR NORMAL OR SLIGHTLY
INCREASED ABOVE-NORMAL PRECIPITATION PROBABILITIES FOR MUCH OF THE WESTERN
CONUS. IT SHOULD BE NOTED THAT PRECIPITATION AMOUNTS ARE LIKELY TO BE ON THE
LIGHTER SIDE.
AN AMPLIFIED 500-HPA TROUGH AND ENHANCED ONSHORE FLOW FAVOR ABOVE-NORMAL
PRECIPITATION ACROSS 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 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 WEST.
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:
19600924 - 20030921 - 20071001 - 20080926 - 19980913
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:
19600923 - 19880920 - 20030920 - 20020918 - 20050918
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 09 - 13 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A N NRN CALIF A A
SRN CALIF A N IDAHO A B NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A N ARIZONA A N COLORADO A N
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 B B KENTUCKY B B
TENNESSEE B B ALABAMA B 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 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 A A AK N SLOPE A B
AK ALEUTIAN B N AK WESTERN N B AK INT BSN A N
AK S INT N A AK SO COAST N A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 11 - 17 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A N NRN CALIF A A
SRN CALIF A N IDAHO A B NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A N ARIZONA A N COLORADO A N
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 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 N B FL PENIN N 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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