798
FXUS06 KWBC 202003
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST TUE FEBRUARY 20 2024
6-10 DAY OUTLOOK FOR FEB 26 - MAR 01, 2024
MODELS ARE IN GOOD AGREEMENT ON THE MEAN PLACEMENT OF THE LARGE-SCALE MID-LEVEL
FEATURES, BUT THE DETAILS ON THE EVOLUTION OF THE PATTERN AND ON THE STRENGTH
AND PLACEMENT OF INDIVIDUAL SYSTEMS ARE LESS CLEAR. MOST TOOLS CENTER A MEAN
NEGATIVE 500-HPA HEIGHT ANOMALY OVER FAR WESTERN CANADA, WITH NEGATIVE HEIGHT
ANOMALIES COVERING A LARGE AREA FROM ALASKA TO MOST OF THE WESTERN AND CENTRAL
CONTIGUOUS UNITED STATES (CONUS). DOWNSTREAM, MODELS GENERALLY AGREE THAT
POSITIVE 500-HPA HEIGHT ANOMALIES WILL EXTEND FROM THE FAR SOUTHERN TIER OF THE
CONUS THROUGH MUCH OF EASTERN NORTH AMERICA.
THE CONSISTENCY IN THE MEAN 500-HPA FIELDS, HOWEVER, IS NOT MATCHED IN THE
DAILY EVOLUTION OF INDIVIDUAL FEATURES. THE PERIOD BEGINS WITH A MID-LEVEL
TROUGH POSITIONED INLAND OVER THE WESTERN CONUS IN BOTH THE EUROPEAN ENSEMBLE
MEAN AND THE GEFS, BUT FROM THERE, THE GEFS TAKES A COHERENT MID-LEVEL SYSTEM
EASTWARD INTO THE NORTH-CENTRAL CONUS BEFORE RE-LOADING THE MID-LEVEL TROUGH
CONSIDERABLY WEST OF THE CONUS PACIFIC COAST. IN CONTRAST, THE EUROPEAN
ENSEMBLE MEAN WASHES OUT THE INITIAL TROUGH QUICKLY AND KEEPS A STRONGER TROUGH
AXIS ANCHORED SLIGHTLY WEST OF THE CONUS. THE EUROPEAN ENSEMBLE MEAN KEEPS MUCH
OF THE WEST COAST - ESPECIALLY THE NORTHWEST - IN A FAVORABLE POSITION FOR
CONSISTENT MODERATE TO HEAVY PRECIPITATION FOR MOST OF THE PERIOD, WHILE THE
GEFS SCENARIO FAVORS DECREASED PRECIPITATION AROUND THE MIDDLE OF THE PERIOD
WITH MODERATE PRECIPITATION RE-DEVELOPING TOWARD DAY 10. THIS SHOWS UP SHARPLY
IN THE DIFFERENCES BETWEEN THE PRECIPITATION REFORECASTS FROM THESE TWO
ENSEMBLE SUITES. THIS IS SIMILAR TO THE INCONSISTENCIES SEEN YESTERDAY, BUT THE
GEFS HAS SHIFTED SLIGHTLY TOWARD THE EUROPEAN ENSEMBLE MEAN BY KEEPING A MORE
AMPLIFIED PATTERN LATER IN THE PERIOD. THE SCENARIO SHOWN BY THE EUROPEAN
ENSEMBLE MEAN IS FAVORED DUE TO THE SHIFT IN ITS DIRECTION BY THE GEFS, BUT THE
GEFS SCENARIO REMAINS REASONABLE AND IS NOT COMPLETELY DISCOUNTED. THE CANADIAN
ENSEMBLE MEANS ARE NOT PARTICULARLY CONSISTENT WITH EITHER ITS EARLIER RUNS,
NOR THE SOLUTIONS FROM THE GEFS AND EUROPEAN ENSEMBLES, AND SO IS NOT FAVORED
AT THIS TIME. THUS THE FORECAST REFLECTS A BLEND OF SOLUTIONS LEANING TOWARD
THE EUROPEAN ENSEMBLES AND ITS DERIVED TOOLS, WITH SURPLUS PRECIPITATION
FAVORED FROM THE ROCKIES WESTWARD. ODDS FOR WETNESS EXCEED 50 PERCENT IN PARTS
OF THE SOUTHWEST AND ACROSS THE NORTHWESTERN CONUS.
ELSEWHERE, THE PRECIPITATION FORECAST TOOLS ARE MORE SIMILAR, AND THE OFFICIAL
FORECAST IS A BLEND OF THESE SOLUTIONS, FAVORING ABOVE-NORMAL PRECIPITATION
ALONG THE NORTHERN TIER OF STATES, THE OHIO VALLEY, AND ADJACENT AREAS. THERE
ARE REDUCED CHANCES FOR HEAVY PRECIPITATION IN THE GREAT PLAINS - ESPECIALLY
THE SOUTHERN HALF - WHICH IS CONSISTENT WITH A POTENTIAL STORM TRACK FROM THE
ROCKIES TOWARD THE GREAT LAKES FOLLOWING THE INITIAL MID-LEVEL SHORTWAVE TROUGH.
THE AFOREMENTIONED UNCERTAINTIES IN THE MID-LEVEL PATTERN DO NOT IMPLY
SIGNIFICANTLY DIFFERENT TEMPERATURE PATTERNS ACROSS NORTH AMERICA. ABOVE-NORMAL
TEMPERATURES ARE FAVORED UPSTREAM FROM THE WESTERN CONUS TROUGH AXIS AND UNDER
THE ABOVE-NORMAL MID-LEVEL HEIGHTS COVERING THE EASTERN CONUS. THIS AREA IS
EXPECTED TO EXPERIENCE PRIMARILY SOUTHERLY OR SOUTHWESTERLY SURFACE FLOW, WHICH
ALSO FAVORS MILD WEATHER ACROSS THIS REGION. ODDS FOR WARMTH EXCEED 80 PERCENT
OVER A LARGE AREA FROM THE CENTRAL GREAT PLAINS EASTWARD THROUGH THE OHIO
VALLEY, SOUTHERN GREAT LAKES REGION, MID-ATLANTIC REGION, AND LOWER NORTHEAST.
IN THE WEST, MOST TOOLS FORECAST SUBNORMAL TEMPERATURES, BUT THE REFORECAST
TOOLS FOR THE ENSEMBLES ARE MILDER, SHOWING NEAR- TO ABOVE-NORMAL TEMPERATURES
THERE. THE FORECAST LEANS TOWARD THE PREPONDERANCE OF TOOLS, FAVORING
BELOW-NORMAL TEMPERATURES. THIS SOLUTION IS ALSO SUPPORTED BY THE ANOMALOUSLY
LOW 500-HPA HEIGHTS IN THE REGION.
WITH BELOW-NORMAL 500-HPA HEIGHTS DOMINATING ALASKA AND A MEAN SURFACE LOW
PRESSURE SYSTEM SOMEWHERE NEAR THE SOUTH-CENTRAL OR SOUTHEASTERN COASTLINE,
BELOW-NORMAL TEMPERATURES ARE OVERWHELMINGLY FAVORED ACROSS MOST OF THE STATE,
WITH THE BEST ODDS (OVER 80 PERCENT) ACROSS THE SOUTHEASTERN ONE-THIRD OF THE
MAINLAND. THERE IS MORE UNCERTAINTY IN SOUTHEASTERN ALASKA, WHERE MILD SURFACE
FLOW FROM THE SOUTH (NEAR THE MEAN SURFACE LOW POSITION) COULD BRING
TEMPERATURES CLOSER TO NORMAL, BUT SUBNORMAL TEMPERATURES OVERALL ARE STILL
SOMEWHAT FAVORED. MOST OF ALASKA - BEING NEAR OR UPSTREAM FROM THE MEAN
MID-LEVEL TROUGH POSITION - HAVE ELEVATED CHANCES OF BEING DRIER THAN NORMAL
EXCEPT NEAR THE PACIFIC COASTLINE CLOSER TO THE MEAN LOCATION OF SURFACE LOW
PRESSURE CENTER. THIS CIRCULATION WOULD BRING ONSHORE FLOW INTO SOUTHEASTERN
ALASKA AT TIMES, WHICH SUPPORTS A FORECAST LEANING TOWARD ABOVE-NORMAL
PRECIPITATION.
WETTER THAN NORMAL CONDITIONS ARE MARGINALLY FAVORED ACROSS HAWAII UPSTREAM
FROM A MID-LEVEL TROUGH. THE FAR WESTERN ISLANDS (INCLUDING KAUAI) HAVE
SLIGHTLY ELEVATED CHANCES FOR ABOVE-NORMAL TEMPERATURES, BUT SOME OF THE TOOLS
ELSEWHERE ARE COOLER THAN YESTERDAY, SO THERE ARE EQUAL TEMPERATURE CHANCES
OVER THE REST OF THE STATE.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 35% OF TODAY'S GFS
SUPERENSEMBLE MEAN CENTERED ON DAY 8, 50% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 15% OF YESTERDAY'S 12Z CANADIAN ENSEMBLE MEAN CENTERED
ON DAY 7
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOUT NORMAL, 3 OUT OF 5, WITH
UNCERTAINTIES IN THE EVOLUTION OF FEATURES OFFSET BY BETTER AGREEMENT ON THE
MEAN PATTERN AND THE DERIVED TEMPERATURE AND PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR FEB 28 - MAR 05, 2024
THE DIFFERENCES IN THE MODELS DURING THE 6- TO 10-DAY PERIOD EXTRAPOLATE INTO
WEEK-2, WITH DECENT AGREEMENT ON THE LARGE-SCALE MEAN PATTERN BUT MODEL
DIFFERENCES IN THE EVOLUTION OF INDIVIDUAL FEATURES. A FAIRLY STRONG MID-LEVEL
RIDGE IS FORECAST SOUTH OR SOUTHWEST OF THE ALEUTIANS WHILE A MID-LEVEL TROUGH
WITH SUBNORMAL 500-HPA HEIGHTS HAS AN AXIS NEAR EASTERN MAINLAND ALASKA AND
NEAR THE WESTERN NORTH AMERICAN COAST. THE 500-HPA HEIGHT PATTERN IS SIMILAR TO
THE 6- TO 10-DAY MEAN HEIGHT PATTERN FARTHER EAST. THE CONUS IS DIVIDED
APPROXIMATELY IN HALF, WITH BELOW-NORMAL MID-LEVEL HEIGHTS OVER MOST OF THE
WESTERN HALF, AND MID-LEVEL RIDGING COVERING THE EASTERN HALF WITH THE MAXIMUM
ANOMALIES CENTERED OVER ATLANTIC CANADA. THE ONLY EXCEPTION IS ALONG THE
SOUTHERN TIER OF THE WESTERN CONUS, WHERE MID-LEVEL HEIGHTS ARE EXPECTED TO BE
NEAR NORMAL.
THE EVOLUTION OF INDIVIDUAL FEATURES FROM THE NORTH PACIFIC INTO THE WESTERN
CONUS REMAINS VERY UNCERTAIN DURING THIS PERIOD, WITH THE EUROPEAN ENSEMBLES
AND ITS DERIVED TOOLS REMAINING CONSIDERABLY WETTER THAN THE GEFS TOOLS.
HOWEVER, ALL MODELS SHOW BELOW-NORMAL MID-LEVEL HEIGHTS OVER THE WEST NORTH OF
THE DESERTS, WITH MEAN SURFACE LOW PRESSURE NEAR SOUTHEASTERN ALASKA RESULTING
IN FREQUENT ONSHORE FLOW, ESPECIALLY IN THE PACIFIC NORTHWEST. THUS, ALTHOUGH
THE TIMING AND INTENSITY OF PRECIPITATION EPISODES DIFFER AMONG THE TOOLS, MOST
SIGNS POINT TOWARD MORE PRECIPITATION THAN NORMAL FOR THE WEST, AND THIS IS
REFLECTED IN THE FORECAST. THE EXCEPTION IS IN THE SOUTHERN ROCKIES AND PARTS
OF THE DESERT SOUTHWEST, SINCE MID-LEVEL SHORTWAVES AND STORMINESS PRIMARILY
AFFECT AREAS FARTHER NORTH, RESULTING IN NO TILT OF THE ODDS TOWARD EITHER
PRECIPITATION EXTREME THERE.
FARTHER EAST, WITH A LOT OF UNCERTAINTY IN THE DAY-TO-DAY EVOLUTION OF
INDIVIDUAL FEATURES, THE FORECAST LEANS TOWARD IMPLICATIONS OF THE MEAN
MID-LEVEL PATTERN AND THE DERIVED TOOLS. AREAS FROM THE ROCKIES EASTWARD SHOULD
BE EXPERIENCING A PREVAILING SURFACE FLOW FROM THE SOUTHWEST OR SOUTH AND
CYCLONICALLY-CURVED MID-LEVEL FLOW EXTENDING FROM THE WESTERN TROUGH TO THE
RIDGE AXIS JUST EAST OF THE CONUS - A PATTERN THAT LEANS TOWARD ABOVE-NORMAL
PRECIPITATION ACROSS MOST OF THE CONUS. ONE EXCEPTION IS ACROSS PARTS OF THE
CENTRAL AND SOUTHERN PLAINS, WHERE SOUTHWESTERLY SURFACE FLOW WOULD BRING IN
RELATIVELY DRY AIR, TEMPERING THE PRECIPITATION FORECAST WHICH FAVORS NEITHER
PRECIPITATION EXTREME.
THERE REMAINS A STRONG TILT TOWARD ABOVE-NORMAL TEMPERATURES EAST OF THE
ROCKIES, WITH ODDS EXCEEDING 70 PERCENT FROM THE MIDDLE MISSISSIPPI VALLEY
EASTWARD INTO THE NORTHEASTERN CONUS AND THE MID-ATLANTIC REGION. ONCE AGAIN,
RAW AND BIAS-CORRECTED OUTPUT FROM THE ENSEMBLE MEANS FAVOR COLDER THAN NORMAL
CONDITIONS FROM THE ROCKIES WESTWARD WHILE THE REFORECAST PRODUCTS SHOW MILDER
CONDITIONS. AS IN THE 6- TO 10-DAY FORECAST, THE PREPONDERANCE OF THE GUIDANCE
IMPLIES COOLER THAN NORMAL CONDITIONS IN THE WEST, AND THAT IS REFLECTED IN THE
OFFICIAL FORECAST.
THE STRONG MID-LEVEL TROUGH NEAR ALASKA AND BELOW-NORMAL 500-HPA HEIGHTS
STATEWIDE CONTINUE TO HEAVILY FAVOR COLDER THAN NORMAL WEATHER THROUGHOUT
WEEK-2, WITH ODDS EXCEEDING 80 PERCENT ACROSS THE SOUTHERN HALF OF THE
MAINLAND. CHANCES FOR COOLER THAN NORMAL CONDITIONS ARE LESS ROBUST OVER
SOUTHEASTERN ALASKA, WHERE SOUTHERLY SURFACE FLOW TO THE EAST OF MEAN SURFACE
LOW PRESSURE MAY AT LEAST OCCASIONALLY DISPLACE ARCTIC AIR FROM THE NORTH. THIS
LATTER REGION IS ALSO EXPECTED TO BE WETTER THAN NORMAL, BEING EAST OF THE MEAN
SURFACE LOW PRESSURE AND MID-LEVEL TROUGH LOCATIONS. BOTH OF THESE SIGNALS IN
SOUTHEASTERN ALASKA, HOWEVER, ARE SLIGHTLY LESS ROBUST THAN YESTERDAY.
MEANWHILE, MOST OTHER PARTS OF THE STATE ARE EXPECTED TO BE DRIER THAN NORMAL
NEAR AND WEST OF THE TROUGH AXIS.
HAWAII MAY BE IN A BIT OF A TRANSITIONAL PATTERN, SO THE ENHANCED CHANCES FOR
ABOVE-NORMAL TEMPERATURES SEEN YESTERDAY HAS BEEN REMOVED TODAY IN FAVOR OF
NEAR-NORMAL TEMPERATURES. THE BLEND OF TOOLS SHOWS A SLIGHTLY ENHANCED CHANCE
FOR WETTER-THAN-NORMAL CONDITIONS STATEWIDE, AND THIS IS REFLECTED IN THE
OFFICIAL WEEK-2 FORECAST.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 50% OF TODAY'S GFS
SUPERENSEMBLE MEAN CENTERED ON DAY 11, 25% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 25% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: NEAR NORMAL, 3 OUT OF 5, WITH
LARGE UNCERTAINTIES IN THE EVOLUTION OF INDIVIDUAL FEATURES TEMPERED BY BETTER
AGREEMENT IN THE MEAN POSITION OF 500-HPA ANOMALIES AND MODEL-DERIVED
TEMPERATURE AND PRECIPITATION OUTPUTS.
FORECASTER: RICH TINKER
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
MARCH 21.
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:
19590218 - 19700224 - 20010219 - 19800302 - 19730224
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:
19590218 - 19800302 - 20010218 - 19750304 - 19700224
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR FEB 26 - MAR 01, 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B A
SRN CALIF B A IDAHO B A NEVADA B A
W MONTANA B A E MONTANA N A WYOMING N A
UTAH B A ARIZONA B A COLORADO A A
NEW MEXICO A A N DAKOTA A A S DAKOTA A A
NEBRASKA A N KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS A N W TEXAS A N
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A N LOUISIANA A N WISCONSIN A A
ILLINOIS A A MISSISSIPPI A N MICHIGAN A A
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A A NEW JERSEY A A W VIRGINIA A A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A B AK N SLOPE B B
AK ALEUTIAN B N AK WESTERN B B AK INT BSN B B
AK S INT B N AK SO COAST B N AK PNHDL B A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR FEB 28 - MAR 05, 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B A
SRN CALIF B A IDAHO B A NEVADA B A
W MONTANA B A E MONTANA N A WYOMING N A
UTAH B A ARIZONA B N COLORADO N N
NEW MEXICO N N N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A N OKLAHOMA A N
N TEXAS A N S TEXAS A A W TEXAS A N
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN A A
ILLINOIS A A MISSISSIPPI A A MICHIGAN A A
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A A NEW JERSEY A A W VIRGINIA A A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE B B
AK ALEUTIAN B N AK WESTERN B N AK INT BSN B B
AK S INT B N AK SO COAST B N 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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