017
FXUS06 KWBC 161909
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE MAY 16 2023
6-10 DAY OUTLOOK FOR MAY 22 - 26 2023
DYNAMICAL MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE 500-HPA GEOPOTENTIAL
HEIGHT PATTERN ACROSS THE FORECAST DOMAIN DURING THE 6-10 DAY PERIOD. THE
PRIMARY LONGWAVE FEATURES INCLUDE A TROUGH OVER SOUTHWESTERN ALASKA, A TROUGH
NEAR THE WEST COAST OF THE CONTIGUOUS U.S. (CONUS), A WEAK RIDGE OVER
NORTHWESTERN CANADA AND EASTERN ALASKA, A RIDGE OVER THE CENTRAL CONUS, AND A
FULL-LATITUDE TROUGH OVER EASTERN NORTH AMERICA. IN RECENT WEEKS, THE ENSEMBLE
MEAN 500-HPA HEIGHT FORECASTS OVER ALASKA FEATURED EITHER A MEAN TROUGH OVER
SOUTHWESTERN ALASKA AND RIDGE EXTENDING FROM WESTERN CANADA INTO EASTERN
ALASKA, OR A BROAD TROUGH ACROSS THE STATE. THE MANUAL 500-HPA HEIGHT BLEND
DEPICTS ABOVE-AVERAGE HEIGHTS FOR ALASKA AND MOST OF THE CONUS DURING THE 6-10
DAY PERIOD, WITH NEAR-AVERAGE HEIGHTS INDICATED FOR THE GULF COAST REGION AND
MUCH OF THE SOUTHEAST.
ABOVE-NORMAL TEMPERATURES ARE FAVORED FROM MOST OF THE WESTERN AND
NORTH-CENTRAL CONUS EASTWARD OVER THE GREAT LAKES AND NORTHEAST, ASSOCIATED
WITH MID-LEVEL RIDGING AND/OR ABOVE-AVERAGE 500-HPA HEIGHTS. THE HIGHEST
PROBABILITIES FOR ABOVE-NORMAL TEMPERATURES (IN EXCESS OF 70 PERCENT) ARE
INDICATED OVER A RELATIVELY SMALL AREA CENTERED ON THE BLACK HILLS OF SOUTH
DAKOTA. ABOVE-NORMAL TEMPERATURES ARE ALSO FAVORED FOR SOUTHERN FLORIDA,
SUPPORTED BY THE TEMPERATURE CONSOLIDATION AND AUTO-TEMPERATURE FORECASTS.
ELEVATED PROBABILITIES OF BELOW-NORMAL TEMPERATURES ARE FORECAST FOR PORTIONS
OF THE SOUTHERN PLAINS AND MUCH OF THE SOUTHERN ATLANTIC REGION. THIS IS
ASSOCIATED WITH INCREASED PRECIPITATION AND CLOUD COVER ANTICIPATED OVER THESE
AREAS, AND ARE SUPPORTED BY THE BIAS-CORRECTED TEMPERATURE FORECASTS. CHANCES
FOR BELOW-NORMAL TEMPERATURES ARE INCREASED OVER PARTS OF SOUTHWESTERN ALASKA,
LARGELY DUE TO THE PROXIMITY OF A MID-LEVEL TROUGH. PROBABILITIES FOR
ABOVE-NORMAL TEMPERATURES ARE SLIGHTLY ENHANCED OVER PORTIONS OF EASTERN
ALASKA, ASSOCIATED WITH A NEARBY MID-LEVEL RIDGE AND ABOVE-AVERAGE HEIGHTS.
DRIER NORTHERLY FLOW ANTICIPATED OVER WESTERN PORTIONS OF WASHINGTON AND OREGON
FAVORS BELOW-NORMAL PRECIPITATION FOR THE 6-10 DAY PERIOD. ODDS FOR
BELOW-NORMAL PRECIPITATION ARE ALSO FAVORED FROM MUCH OF THE MISSISSIPPI VALLEY
NORTHEASTWARD ACROSS THE CENTRAL AND EASTERN GREAT LAKES REGION, THE OHIO AND
TENNESSEE VALLEYS, AND THE ATLANTIC COAST STATES FROM MAINE SOUTHWESTWARD TO
WEST VIRGINIA. THIS IS CONSISTENT WITH THE BROAD AREA OF SUBSIDENCE EXPECTED
BETWEEN THE RIDGE AXIS OVER THE CENTRAL STATES AND THE DOWNSTREAM TROUGH AXIS
CENTERED NEAR THE APPALACHIANS, AND IS SUPPORTED BY THE PRECIPITATION
CONSOLIDATION TOOL AND CALIBRATED REFORECAST PRECIPITATION. SURFACE LOW
PRESSURE DEVELOPMENT OVER FLORIDA DURING THE FORECAST PERIOD AND ASSOCIATED
ONSHORE FLOW INCREASES THE PROBABILITIES OF ABOVE-NORMAL PRECIPITATION FOR THE
SOUTHERN ATLANTIC REGION AND EASTERN PORTIONS OF THE GULF COAST REGION. THOUGH
ITS FUTURE PATH IS UNCLEAR DUE TO A POSSIBLE COLLAPSE OF MID-LEVEL STEERING
CURRENTS, A PROLONGED PERIOD OF MOIST, EAST TO SOUTHEAST FLOW IS EXPECTED ALONG
THE SOUTHEAST COAST. RAW PRECIPITATION PROBABILITIES AND CALIBRATED REFORECAST
PRECIPITATION INCREASE THE ODDS OF ABOVE-NORMAL PRECIPITATION FOR APPROXIMATELY
THE SOUTHWESTERN QUARTER OF THE CONUS, WITH MAXIMUM PROBABILITIES EXCEEDING 50
PERCENT OVER MUCH OF THE FOUR CORNERS REGION. THIS IS ASSOCIATED WITH INCREASED
MOISTURE OUT AHEAD OF THE WEST COAST TROUGH, AND IS ANTICIPATED TO BRING
SIGNIFICANT AMOUNTS OF PRECIPITATION TO AT LEAST THE HIGHER ELEVATIONS OF THE
DESERT SOUTHWEST. THIS EVENT IS UNUSUAL FOR MAY, AND IS NOT ASSOCIATED WITH
TYPICAL SUMMER MONSOON PRECIPITATION WHICH NORMALLY BEGINS TOWARDS THE END OF
JUNE OR EARLY JULY. A MODEST TILT TOWARDS ABOVE-NORMAL PRECIPITATION IS
INDICATED NORTH-NORTHEASTWARD TO THE CANADIAN BORDER, FROM MONTANA TO THE UPPER
MISSISSIPPI VALLEY. ABOVE-NORMAL PRECIPITATION IS ALSO FAVORED OVER MUCH OF
ALASKA, AHEAD OF THE MID-LEVEL TROUGH PREDICTED OVER SOUTHWESTERN PORTIONS OF
THE STATE.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 33% 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
FAIRLY GOOD MODEL AGREEMENT REGARDING THE 500-HPA HEIGHT FORECASTS ACROSS NORTH
AMERICA, OFFSET BY DIFFERENCES AMONG THE SURFACE TEMPERATURE AND PRECIPITATION
TOOLS.
8-14 DAY OUTLOOK FOR MAY 24 - 30 2023
DURING WEEK-2 THE MEAN TROUGH OVER THE EASTERN CONUS IS FORECAST TO WEAKEN, AS
500-HPA HEIGHTS RISE ACROSS THE REGION, ESPECIALLY ACROSS THE GREAT LAKES AND
NORTHEAST. A MID-LEVEL RIDGE IS PREDICTED OVER THE CENTRAL CONUS, AND A TROUGH
IS EXPECTED TO PERSIST NEAR THE WEST COAST. A MID-LEVEL TROUGH IS INDICATED
ALONG THE BERING SEACOAST OF ALASKA, WITH MUCH OF ITS SHORTWAVE ENERGY
PROGRESSING EASTWARD ACROSS THE NORTHERN GULF OF ALASKA. MOST ENSEMBLE MEANS
AND DETERMINISTIC SOLUTIONS PREDICT WEAK RIDGING FROM WESTERN CANADA INTO
EASTERN AND CENTRAL ALASKA. THE 6Z GEFS IS ONE OF THE FEW MODEL SOLUTIONS WHICH
DEPICT A TROUGH OVER MOST OF ALASKA.
DURING WEEK-2, INCREASED PROBABILITIES OF ABOVE-NORMAL TEMPERATURES ARE
FORECAST FOR APPROXIMATELY THE NORTHERN TWO-THIRDS OF THE CONUS UNDERNEATH
ANOMALOUS RIDGING. THIS IS WELL SUPPORTED BY THE CALIBRATED REFORECAST
TEMPERATURES, THE TEMPERATURE CONSOLIDATION TOOL, AND THE AUTO-TEMPERATURE
FORECAST. PROBABILITIES OF ABOVE-NORMAL TEMPERATURES EXCEED 60 PERCENT FROM
SOUTH DAKOTA AND NEBRASKA EASTWARD ACROSS THE SOUTHERN GREAT LAKES REGION.
CONVERSELY, PROBABILITIES FOR BELOW-NORMAL TEMPERATURES ARE ELEVATED ACROSS
PARTS OF THE SOUTHEAST, THE SOUTHERN PLAINS, AND FAR SOUTHERN CALIFORNIA AND
ADJACENT PARTS OF ARIZONA, ASSOCIATED WITH INCREASED PRECIPITATION AND CLOUD
COVER. CHANCES FOR BELOW-NORMAL TEMPERATURES ARE INCREASED OVER SOUTHWESTERN
AND SOUTH-CENTRAL ALASKA, ASSOCIATED WITH A MID-LEVEL TROUGH. WITH SNOW COVER
DECREASING SUBSTANTIALLY ACROSS THE STATE, THE BIAS-CORRECTED TEMPERATURE TOOLS
MAY BE ARTIFICIALLY PROLONGING THE DURATION OF ANY PERIOD OF BELOW-NORMAL
TEMPERATURES.
INCREASED PROBABILITIES FOR ABOVE-NORMAL PRECIPITATION ARE FAVORED OVER MOST OF
THE WESTERN HALF OF THE CONUS EXTENDING EASTWARD INTO THE UPPER MISSISSIPPI
VALLEY. THIS WIDESPREAD AREA LIES ALONG AND EAST OF A MID-LEVEL TROUGH, WITH
ACCESS TO MOISTURE FROM THE EASTERN PACIFIC OCEAN AND GULF OF MEXICO.
ABOVE-NORMAL PRECIPITATION IS ALSO FAVORED FROM THE CENTRAL GULF COAST REGION
EAST-NORTHEASTWARD TO THE SOUTHERN ATLANTIC COAST, AND IS ASSOCIATED WITH A
SLOW-MOVING LOW PRESSURE SYSTEM. PROBABILITIES OF ABOVE-NORMAL PRECIPITATION
EXCEED 50 PERCENT OVER MOST OF FLORIDA AND ADJACENT PARTS OF GEORGIA. WITH THE
PREDICTED WEAKENING OF THE EASTERN CONUS TROUGH, MID-LEVEL STEERING CURRENTS
COULD COLLAPSE. AT THIS TIME, IT IS UNCLEAR AS TO WHETHER THE LOW PRESSURE
SYSTEM IN THIS REGION WILL SHIFT NORTHEASTWARD OFF THE SOUTHEAST COAST, OR
WESTWARD ALONG THE GULF COAST, AND TO WHAT DEGREE IT MAY STRENGTHEN.
ABOVE-AVERAGE 500-HPA HEIGHTS AND SUFFICIENT DISTANCE FROM STORM TRACKS FAVOR
MODESTLY INCREASED CHANCES FOR BELOW-NORMAL PRECIPITATION FOR ILLINOIS, THE
OHIO VALLEY, AND THE CENTRAL AND EASTERN GREAT LAKES REGION INTO THE NORTHEAST.
ELEVATED CHANCES FOR ABOVE-NORMAL PRECIPITATION ARE FAVORED OVER EASTERN ALASKA
IN ADVANCE OF A MID-LEVEL TROUGH. BELOW-NORMAL PRECIPITATION IS SLIGHTLY
FAVORED OVER THE VICINITY OF THE ALASKA PENINSULA.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 33% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: NEAR-AVERAGE, 3 OUT OF 5, DUE TO
UNCERTAINTIES IN THE EXPECTED EVOLUTION OF THE MID-LEVEL HEIGHT PATTERN, AND
THE UNCERTAINTY ASSOCIATED WITH POTENTIAL STORM DEVELOPMENT IN THE VICINITY OF
FLORIDA DURING WEEK-2.
FORECASTER: ANTHONY A
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:
19570505 - 19890428 - 19860528 - 19720527 - 19760428
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:
19890428 - 19570504 - 19860528 - 19720527 - 19760427
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 22 - 26 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A N NRN CALIF A A
SRN CALIF A A IDAHO A A NEVADA A A
W MONTANA A A E MONTANA A A WYOMING A A
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO N A N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA N A
N TEXAS B N S TEXAS B N W TEXAS B A
MINNESOTA A A IOWA A N MISSOURI A B
ARKANSAS N B LOUISIANA N N WISCONSIN A N
ILLINOIS A B MISSISSIPPI N N MICHIGAN A B
INDIANA A B OHIO N B KENTUCKY N B
TENNESSEE N B ALABAMA N A NEW YORK A B
VERMONT A B NEW HAMP N B MAINE A B
MASS N B CONN N B RHODE IS N N
PENN N B NEW JERSEY N N W VIRGINIA N B
MARYLAND N N DELAWARE N N VIRGINIA N N
N CAROLINA B A S CAROLINA B A GEORGIA B A
FL PNHDL B A FL PENIN A A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B N AK INT BSN N A
AK S INT N A AK SO COAST N A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 24 - 30 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A N OREGON A A NRN CALIF N A
SRN CALIF B A IDAHO A A NEVADA A A
W MONTANA A A E MONTANA A A WYOMING A A
UTAH A A ARIZONA N A COLORADO A A
NEW MEXICO N A N DAKOTA A A S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS N A S TEXAS B N W TEXAS B A
MINNESOTA A A IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA N A WISCONSIN A N
ILLINOIS A N MISSISSIPPI N N MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA N N NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS A N
PENN A N NEW JERSEY A N W VIRGINIA A N
MARYLAND A N DELAWARE A N VIRGINIA N N
N CAROLINA N A S CAROLINA B A GEORGIA B A
FL PNHDL B A FL PENIN N A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B N AK INT BSN N A
AK S INT N A AK SO COAST B A AK PNHDL N N
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.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page