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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 FRI APRIL 21 2023
6-10 DAY OUTLOOK FOR APR 27 - MAY 01, 2023
MODEL SOLUTIONS ARE IN EXCELLENT AGREEMENT AND REMAIN CONSISTENT THAT A
WEST-BASED NEGATIVE NORTH ATLANTIC OSCILLATION (NAO) PERSISTS FROM LATE APRIL
INTO THE BEGINNING OF MAY. THIS -NAO ALONG WITH ANOMALOUS RIDGING UPSTREAM
SUPPORTS INCREASED PROBABILITIES FOR BELOW-NORMAL TEMPERATURES ACROSS MUCH OF
THE EASTERN TWO-THIRDS OF THE CONUS. HOWEVER, ABOVE-NORMAL TEMPERATURES ARE
FAVORED FOR THE FLORIDA PENINSULA WHERE ANOMALOUS WARMTH IS FORECAST THROUGH AT
LEAST DAY 7. NEW ENGLAND IS EXPECTED TO BE NORTHEAST OF THE STRONGEST COLD AIR
ADVECTION WITH NEAR NORMAL TEMPERATURES MORE LIKELY FOR THIS REGION. FARTHER TO
THE WEST, THE ANOMALOUS RIDGING FAVORS ABOVE-NORMAL TEMPERATURES FOR THE
WESTERN THIRD OF THE CONUS.
THE MADDEN-JULIAN OSCILLATION (MJO) IS CURRENTLY CENTERED ACROSS THE EAST
PACIFIC AND IS FORECAST TO CONTINUE PROPAGATING EASTWARD FROM THE AMERICAS TO
AFRICA. THIS MJO EVOLUTION TYPICALLY ENHANCES SUBTROPICAL MOISTURE ACROSS THE
SOUTHERN TIER OF THE CONUS. FROM DAYS 6 TO 8 (APRIL 27-29), THE ENSEMBLE MEANS
AND THEIR DETERMINISTIC MODEL RUNS DEPICT A LOW PRESSURE SYSTEM AND TRAILING
COLD FRONT SLOWLY PROGRESSING EASTWARD FROM THE MISSISSIPPI VALLEY TO THE EAST
COAST. ABOVE-NORMAL PRECIPITATION IS FAVORED FOR THE EASTERN CONUS WITH THE
LARGEST PROBABILITIES LOCATED ALONG COASTAL AREAS OF THE SOUTHEAST AND
MID-ATLANTIC, CONSISTENT WITH MJO COMPOSITES AND THE DYNAMICAL MODELS. ELEVATED
PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION EXTEND WESTWARD TO THE RIO GRANDE
VALLEY AND SOUTHERN HIGH PLAINS, ASSOCIATED WITH A STATIONARY FRONT. AN
AMPLIFIED RIDGE SUPPORTS INCREASED BELOW-NORMAL PRECIPITATION PROBABILITIES FOR
THE PACIFIC NORTHWEST, NORTHERN AND CENTRAL CALIFORNIA, NORTHERN ROCKIES, AND
GREAT BASIN. COMPARED TO YESTERDAY, THE 6-10 DAY OUTLOOK IS DRIER ACROSS THE
SOUTHERN GREAT PLAINS AND OZARKS SINCE A LOW PRESSURE SYSTEM IS FORECAST TO
MOVE AWAY FROM THESE AREAS BY DAY 6 AND PREDICTED HEAVIER PRECIPITATION TIMES
OFF.
A HIGH AMPLITUDE TROUGH WITH NEGATIVE 500-HPA HEIGHT ANOMALIES FAVORS
BELOW-NORMAL TEMPERATURES ACROSS THE ALEUTIANS AND THE WESTERN TWO-THIRDS OF
MAINLAND ALASKA. AN INCREASE IN 500-HPA HEIGHTS LATER IN THIS PERIOD FAVOR NEAR
TO ABOVE-NORMAL TEMPERATURES FOR THE EASTERN THIRD OF MAINLAND ALASKA AND
SOUTHEASTERN ALASKA. THE PATTERN ALOFT AND AT THE SURFACE SUPPORT INCREASED
CHANCES FOR ABOVE-NORMAL PRECIPITATION THROUGHOUT A MAJORITY OF ALASKA.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 35% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 35% 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 MODEL AGREEMENT AND CONTINUITY.
8-14 DAY OUTLOOK FOR APR 29 - MAY 05, 2023
THE CANADIAN, GFS, AND ECMWF ENSEMBLE MEANS DEPICT A BLOCKING RIDGE CENTERED
OVER BAFFIN ISLAND WITH A HIGHLY AMPLIFIED TROUGH ACROSS THE EAST. THEREFORE, A
LARGE COVERAGE OF BELOW-NORMAL TEMPERATURES ARE FAVORED FOR A MAJORITY OF THE
EASTERN TWO-THIRDS OF THE CONUS. AN AMPLIFIED RIDGE CONTINUES TO FAVOR
ABOVE-NORMAL TEMPERATURES FOR THE PACIFIC NORTHWEST, GREAT BASIN, AND NORTHERN
ROCKIES. AS A TROUGH STRENGTHENS AND SHIFTS EAST TO THE WEST COAST, A COOLING
TREND IS LIKELY ACROSS CALIFORNIA AND THE SOUTHWEST LATER IN WEEK-2. A
PREDICTED VARIABLE TEMPERATURE PATTERN RESULTS IN A FORECAST OF NEAR NORMAL
TEMPERATURES ACROSS THE DESERT SOUTHWEST, WHILE BELOW-NORMAL TEMPERATURES ARE
MORE LIKELY ALONG COASTAL CALIFORNIA AND SOUTHERN CALIFORNIA. A TWO-CATEGORY
CHANGE IN THE TEMPERATURE OUTLOOK FROM THE 6-10 TO 8-14 DAY OUTLOOKS IS
WARRANTED FOR PARTS OF CALIFORNIA AS ANOMALOUS WARMTH ON DAYS 6 AND 7 IS
PREDICTED TO CHANGE TO COOLER-THAN-NORMAL AROUND DAY 11.
DOWNSTREAM OF AN AMPLIFIED LONGWAVE TROUGH AXIS, INCREASED ABOVE-NORMAL
PRECIPITATION PROBABILITIES ARE FORECAST ALONG THE EAST COAST. SLIGHTLY
ELEVATED PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION ARE FORECAST ACROSS THE
LOWER RIO GRANDE VALLEY WHICH IS EXPECTED TO BE CLOSE TO A STATIONARY FRONT
EARLY IN WEEK-2. AS A COLD FRONT SHIFTS SOUTH AND EAST BY DAY 8, A DRIER
OUTLOOK (RELATIVE TO YESTERDAY) IS FORECAST FOR THE CENTRAL TO SOUTHERN
APPALACHIANS, LOWER MISSISSIPPI VALLEY, AND SOUTHERN GREAT PLAINS. THE COVERAGE
OF ENHANCED ABOVE-NORMAL PRECIPITATION PROBABILITIES ARE EXPANDED TO INCLUDE
MORE OF THE WEST TODAY SINCE THERE IS AN INCREASING CHANCE THAT AN AMPLIFIED
TROUGH SHIFTS EAST TO THE WEST COAST LATER IN WEEK-2. ALONG AND TO THE EAST OF
A 500-HPA RIDGE AXIS, ELEVATED PROBABILITIES FOR BELOW-NORMAL PRECIPITATION ARE
FORECAST ACROSS THE NORTHERN TIER OF THE WESTERN AND CENTRAL CONUS ALONG WITH
THE CENTRAL GREAT PLAINS, UPPER TO MIDDLE MISSISSIPPI VALLEY, AND OHIO VALLEY.
ALTHOUGH PROBABILITIES IN THE WEEK-2 PRECIPITATION OUTLOOK ARE LIMITED BASED ON
WEAK SIGNALS AMONG THE REFORECAST TOOLS, THE DYNAMCIAL MODEL OUTPUT IS QUITE
SIMILAR TO THE ANALOG TOOL DERIVED FROM THE MANUAL 500-HPA HEIGHT BLEND.
THE 500-HPA TROUGH AXIS, INITIALLY OVER WESTERN MAINLAND ALASKA, IS FORECAST TO
RETROGRADE WESTWARD TO THE BERING SEA. THIS PATTERN CHANGE RESULTS IN A DRYING
AND WARMING TREND ACROSS SOUTHEASTERN ALASKA FROM THE 6-10 DAY PERIOD.
OTHERWISE, THE NEARBY AMPLIFIED TROUGH CONTINUES TO FAVOR BELOW-NORMAL
TEMPERATURES AND ABOVE-NORMAL PRECIPITATION FOR THE REMAINDER OF ALASKA.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 30% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 35% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 35% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO GOOD
MODEL AGREEMENT AND CONTINUITY ON THE 500-HPA HEIGHT PATTERN OFFSET BY WEAK
SIGNALS AMONG THE PRECIPITATION TOOLS.
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 MAY
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:
20050430 - 19790412 - 19530408 - 20090416 - 19900426
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:
20090415 - 19530407 - 19790412 - 20050429 - 20020401
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR APR 27 - MAY 01, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A B
SRN CALIF A N IDAHO A B NEVADA A B
W MONTANA B B E MONTANA B B WYOMING B B
UTAH A N ARIZONA A N COLORADO B N
NEW MEXICO B N N DAKOTA B N S DAKOTA B N
NEBRASKA B N KANSAS B N OKLAHOMA B N
N TEXAS B N S TEXAS B A W TEXAS B A
MINNESOTA B A IOWA B N MISSOURI B N
ARKANSAS B N LOUISIANA B N WISCONSIN B A
ILLINOIS B N MISSISSIPPI B A MICHIGAN B A
INDIANA B A OHIO B A KENTUCKY B A
TENNESSEE B A ALABAMA B A NEW YORK N A
VERMONT N A NEW HAMP N A MAINE N A
MASS N A CONN N A RHODE IS N A
PENN B A NEW JERSEY B A W VIRGINIA B A
MARYLAND B A DELAWARE B A VIRGINIA B A
N CAROLINA B A S CAROLINA B A GEORGIA B A
FL PNHDL B A FL PENIN A A AK N SLOPE B A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN N A
AK S INT B A AK SO COAST B A AK PNHDL A B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR APR 29 - MAY 05, 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A A NRN CALIF B A
SRN CALIF B A IDAHO A N NEVADA A A
W MONTANA A B E MONTANA B B WYOMING N B
UTAH A A ARIZONA A A COLORADO N N
NEW MEXICO N N N DAKOTA B B S DAKOTA B B
NEBRASKA B B KANSAS B B OKLAHOMA B N
N TEXAS B N S TEXAS B N W TEXAS B N
MINNESOTA B B IOWA B B MISSOURI B B
ARKANSAS B B LOUISIANA B N WISCONSIN B B
ILLINOIS B B MISSISSIPPI B N MICHIGAN B N
INDIANA B B OHIO B N KENTUCKY B B
TENNESSEE B B ALABAMA B N NEW YORK B A
VERMONT B A NEW HAMP B A MAINE B A
MASS B A CONN B A RHODE IS B A
PENN B N NEW JERSEY B A W VIRGINIA B N
MARYLAND B A DELAWARE B A VIRGINIA B N
N CAROLINA B N S CAROLINA B N GEORGIA B N
FL PNHDL B A FL PENIN A A AK N SLOPE B A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN N A
AK S INT N A AK SO COAST N A AK PNHDL A B
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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