018  
FXUS06 KWBC 181903  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EDT THU MAY 18 2023  
 
6-10 DAY OUTLOOK FOR MAY 24 - 28 2023  
 
TODAY'S MODEL SOLUTIONS ARE IN FAIRLY GOOD AGREEMENT ON THE PREDICTED AMPLIFIED  
500-HPA CIRCULATION PATTERN ACROSS NORTH AMERICA AND SURROUNDING REGIONS DURING  
THE 6-10 DAY PERIOD. THE MANUAL 500-HPA HEIGHT BLEND IS BASED PRIMARILY ON THE  
ENSEMBLE MEANS FROM THE GFS, ECMWF, AND CANADIAN MODEL ENSEMBLES DUE TO RECENT  
MODEL SKILL. THE RESULTANT MANUAL BLEND FEATURES MID-LEVEL TROUGHING OVER  
SOUTHWESTERN ALASKA, AND THE WEST COAST OF THE CONTIGUOUS U.S. (CONUS),  
ANOMALOUS RIDGING OVER THE NORTH-CENTRAL AND NORTHEASTERN CONUS, AND A WEAK  
TROUGH OVER SOUTHEASTERN CONUS. ABOVE-AVERAGE HEIGHTS ARE FORECAST FOR ALASKA  
AND MOST OF THE CONUS DURING THE 6-10 DAY PERIOD, WITH WEAK BELOW-NORMAL  
HEIGHTS INDICATED FOR THE GULF COAST REGION AND MUCH OF THE SOUTHEAST AS WELL  
AS PARTS OF SOUTHWESTERN CALIFORNIA.  
 
ENHANCED CHANCES FOR 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 PARTS OF THE NORTHERN AND CENTRAL PLAINS, AND PORTIONS OF  
THE UPPER AND MIDDLE MISSISSIPPI VALLEY. ELEVATED PROBABILITIES OF  
BELOW-NORMAL TEMPERATURES ARE FORECAST FOR PORTIONS OF SOUTHERN TEXAS 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. BELOW-NORMAL PRECIPITATION IS MOST LIKELY OVER SOUTHERN TEXAS.  
THIS IS CONSISTENT WITH 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. RAW PRECIPITATION PROBABILITIES AND  
CALIBRATED REFORECAST PRECIPITATION INCREASE THE ODDS OF ABOVE-NORMAL  
PRECIPITATION FOR APPROXIMATELY THE SOUTHWESTERN QUARTER OF THE CONUS. THIS IS  
ASSOCIATED WITH INCREASED MOISTURE OUT AHEAD OF THE WEST COAST TROUGH. A MODEST  
TILT TOWARDS ABOVE-NORMAL PRECIPITATION IS INDICATED NORTH-NORTHEASTWARD TO THE  
CANADIAN BORDER, FROM MONTANA TO THE UPPER MISSISSIPPI VALLEY. NEAR TO  
BELOW-NORMAL PRECIPITATION IS FAVORED OVER WESTERN ALASKA, WHILE ABOVE-NORMAL  
PRECIPITATION IS LIKELY OVER THE REMAINDER OF THE STATE OF ALASKA, SUPPORTED BY  
THE TEMPERATURE CONSOLIDATION AND AUTO-TEMPERATURE FORECAST TOOLS.  
 
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 40% OF TODAY'S GFS  
SUPERENSEMBLE MEAN CENTERED ON DAY 8, 30% 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: 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 26 - JUN 01, 2023  
 
ENSEMBLE MEAN SOLUTIONS FOR THE 8-14 DAY PERIOD PREDICT A FAIRLY PERSISTENT  
500-HPA CIRCULATION PATTERN ACROSS NORTH AMERICA AND SURROUNDING REGIONS.  
ANOMALOUS MID-LEVEL RIDGING WITH ABOVE-NORMAL 500-HPA HEIGHTS IS PREDICTED OVER  
THE NORTH-CENTRAL AND NORTHEASTERN CONUS, AND A TROUGH IS EXPECTED TO PERSIST  
NEAR THE WEST COAST. A WEAK TROUGH WITH SLIGHTLY BELOW-NORMAL 500-HPA HEIGHTS  
IS SITUATED OVER THE SOUTHEAST. MOST ENSEMBLE MEANS AND DETERMINISTIC SOLUTIONS  
PREDICT WEAK RIDGING FROM WESTERN CANADA INTO 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. CONVERSELY, PROBABILITIES FOR BELOW-NORMAL TEMPERATURES ARE ELEVATED  
ACROSS SOUTHERN TEXAS AND THE SOUTHEAST (EXCEPT FOR SOUTHERN FLORIDA, WHERE  
ABOVE-NORMAL TEMPERATURES ARE INDICATED), ASSOCIATED WITH INCREASED  
PRECIPITATION AND CLOUD COVER. CHANCES FOR BELOW-NORMAL TEMPERATURES ARE  
INCREASED OVER SOUTHWESTERN ALASKA, SUPPORTED BY MOST DYNAMICAL TEMPERATURE  
FORECAST TOOLS. 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. 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, WHILE NEAR-NORMAL PRECIPITATION  
IS SLIGHTLY FAVORED OVER WESTERN ALASKA.  
 
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 30% OF TODAY'S GFS  
SUPERENSEMBLE 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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO  
GOOD MODEL AGREEMENT ON A 500-HPA PATTERN ACROSS MUCH OF THE FORECAST DOMAIN.  
 
FORECASTER: LUKE H  
 
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  
JUNE 15.  
 
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 - 19760428 - 19890428 - 19510507 - 19520516  
 
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:  
19890429 - 19640528 - 19510507 - 19570504 - 19760427  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR MAY 24 - 28 2023  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A B OREGON A B NRN CALIF A A  
SRN CALIF N A IDAHO A A NEVADA A A  
W MONTANA A N E MONTANA A A WYOMING A A  
UTAH A A ARIZONA A N COLORADO A A  
NEW MEXICO A A N DAKOTA A A S DAKOTA A A  
NEBRASKA A A KANSAS A A OKLAHOMA A A  
N TEXAS N N S TEXAS N N W TEXAS N A  
MINNESOTA A A IOWA A A MISSOURI A N  
ARKANSAS A N LOUISIANA N N WISCONSIN A A  
ILLINOIS A B MISSISSIPPI N N MICHIGAN A B  
INDIANA A B OHIO A B KENTUCKY A B  
TENNESSEE N B ALABAMA B N NEW YORK A B  
VERMONT A B NEW HAMP A B MAINE A B  
MASS A B CONN A B RHODE IS A B  
PENN A B NEW JERSEY A B W VIRGINIA A B  
MARYLAND N B DELAWARE N B VIRGINIA B B  
N CAROLINA B A S CAROLINA B A GEORGIA B A  
FL PNHDL B A FL PENIN B A AK N SLOPE N N  
AK ALEUTIAN B N AK WESTERN N 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 26 - JUN 01, 2023  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A N OREGON A N NRN CALIF N A  
SRN CALIF N A IDAHO A A NEVADA A A  
W MONTANA A N E MONTANA A N WYOMING A A  
UTAH A A ARIZONA N N COLORADO A A  
NEW MEXICO N A N DAKOTA A N S DAKOTA A A  
NEBRASKA A A KANSAS A A OKLAHOMA A N  
N TEXAS N N S TEXAS N N W TEXAS N A  
MINNESOTA A A IOWA A N MISSOURI A N  
ARKANSAS A N LOUISIANA N N 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 A 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 A N  
N CAROLINA N A S CAROLINA B A GEORGIA B A  
FL PNHDL B A FL PENIN N A AK N SLOPE N N  
AK ALEUTIAN N N AK WESTERN N N AK INT BSN N N  
AK S INT N N AK SO COAST B N 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.  
 

 
 
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