842  
FXUS06 KWBC 271940  
PMDMRD  
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD  
300 PM EDT THU JULY 27 2017  
 
6-10 DAY OUTLOOK FOR AUG 02 - 06 2017  
 
TODAY'S DYNAMICAL MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE PREDICTED  
MID-TROPOSPHERIC CIRCULATION PATTERN ACROSS THE FORECAST DOMAIN, THOUGH NOT  
QUITE AS GOOD AS YESTERDAY. THE OFFICIAL BLENDED 500-HPA HEIGHT FIELD DEPICTS  
MEAN TROUGHS OVER THE GULF OF ALASKA/EASTERN PACIFIC, AND THE EASTERN CONUS,  
WITH MEAN RIDGES OVER EASTERN ALASKA, THE WESTERN INTERIOR CONUS, AND THE  
ALEUTIANS. THERE ARE RELATIVELY MINOR DIFFERENCES BETWEEN THE DYNAMICAL MODELS  
IN PREDICTED AMPLITUDE AND PHASE OF THESE KEY LONG-WAVE FEATURES. ONE OF THE  
MORE UNCERTAIN ASPECTS OF THIS FORECAST INVOLVES THE LONG-WAVE TROUGH  
ANTICIPATED OVER THE EASTERN CONUS. INSPECTION OF MODEL GUIDANCE INDICATES  
SEVERAL SHORTWAVES EMBEDDED WITHIN THE LONGWAVE TROUGH ARE LIKELY TO MOVE  
ACROSS THE GREAT LAKES REGION AND NORTHEAST, RESULTING IN VARIABLE TEMPERATURE  
AND PRECIPITATION PATTERNS DURING THE 6-10 DAY PERIOD. THIS IS WHY A  
SUBSTANTIAL AREA OF NEAR-NORMAL TEMPERATURES, AND NEAR-NORMAL PRECIPITATION, IS  
FAVORED ACROSS THESE REGIONS. ANOTHER FORECAST ISSUE IS THE EXPECTED AMPLITUDE  
OF THE WESTERN CONUS RIDGE, WITH ECMWF-BASED GUIDANCE DEPICTING MUCH LOWER  
AMPLITUDE WITH THIS FEATURE. AT THE 5820 METER LEVEL, THE VARIOUS SPAGHETTI  
DIAGRAMS SHOW LOW (GFS AND CANADIAN-BASED ENSEMBLES) TO MODERATE (ECMWF-BASED)  
SPREAD AMONG THE INDIVIDUAL ENSEMBLE MEMBERS OVER THE CONUS.  
 
ODDS FOR ABOVE NORMAL TEMPERATURES ARE ELEVATED ACROSS MOST OF ALASKA, MOST  
AREAS WEST OF THE CONTINENTAL DIVIDE, THE NORTHERN GREAT PLAINS AND WESTERN  
NEBRASKA, NORTHWEST MINNESOTA, THE NORTHEAST, THE FLORIDA PENINSULA, AND  
SOUTHERN PORTIONS OF TEXAS. THIS IS GENERALLY DUE TO THE PREDICTED PRESENCE OF  
500-HPA RIDGES AND ASSOCIATED ABOVE NORMAL HEIGHTS. THE FAVORED AREA OF ABOVE  
NORMAL TEMPERATURES ACROSS THE NORTHEAST IS RELATED TO AN APPROACHING 500-HPA  
TROUGH. BELOW NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE CENTRAL AND  
SOUTHERN GREAT PLAINS, APPROXIMATELY THE LOWER HALF OF THE MISSISSIPPI VALLEY,  
THE TENNESSEE VALLEY, THE SOUTHERN APPALACHIANS, AND MOST OF THE SOUTHEAST  
(EXCLUDING FLORIDA). THIS IS DUE TO THE PREDICTED PRESENCE OF A NEARBY 500-HPA  
TROUGH AND LIKELIHOOD FOR ENHANCED RAINFALL, AND IS CONSISTENT WITH VARIOUS  
DYNAMICAL MODEL TEMPERATURE FORECASTS, AND THE CPC CONSOLIDATION TEMPERATURE  
FORECAST.  
 
ABOVE NORMAL PRECIPITATION IS FAVORED IN PORTIONS OF ALASKA, CENTRAL AND  
SOUTHERN PORTIONS OF THE INTERMOUNTAIN REGION, THE EXTREME SOUTHERN ROCKIES,  
THE SOUTHERN PLAINS, THE GULF COAST STATES, AND MUCH OF GEORGIA. THIS IS  
ATTRIBUTED TO THE EXPECTATION OF APPROACHING 500-HPA TROUGHS AND ASSOCIATED  
WIDESPREAD ASCENT OF AIR, AND IN THE SOUTHWESTERN CONUS, A COMBINATION OF A  
BACKDOOR COLD FRONT AND THE SOUTHWEST SUMMER MONSOON. BELOW NORMAL  
PRECIPITATION IS FAVORED OVER THE NORTHERN INTERMOUNTAIN REGION, THE NORTHERN  
ROCKIES, NORTHERN AND CENTRAL PLAINS, THE UPPER AND MIDDLE MISSISSIPPI VALLEY,  
THE SOUTHERN OHIO VALLEY, THE CENTRAL APPALACHIANS, MUCH OF THE MID-ATLANTIC,  
LONG ISLAND, AND SOUTHERN NEW ENGLAND. THIS FAVORED AREA OF BELOW NORMAL  
PRECIPITATION IS ASSOCIATED WITH AN ANTICIPATED 500-HPA RIDGE AND THE  
SUBSIDENCE AREA ASSOCIATED WITH THE EASTERN CONUS TROUGH. THE RESIDUAL AREA OF  
FAVORED BELOW NORMAL PRECIPITATION ACROSS THE GENERAL AREA CENTERED ON THE  
MID-ATLANTIC IS THOUGHT TO BE WELL AHEAD OF AN APPROACHING COLD FRONT.  
 
TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 15% OF TODAY'S 0Z GFS ENSEMBLE MEAN  
CENTERED ON DAY 8, 15% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 10%  
OF TODAY'S OPERATIONAL 0Z GFS CENTERED ON DAY 8, 10% OF TODAY'S OPERATIONAL 6Z  
GFS CENTERED ON DAY 8, 25% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY  
8, 10% OF TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8, AND 15% OF TODAY'S 0Z  
CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8  
 
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: SLIGHTLY ABOVE AVERAGE, 4 OUT OF  
5, DUE TO FAIRLY GOOD MODEL AGREEMENT, AND REASONABLE AGREEMENT AMONG THE  
VARIOUS TEMPERATURE AND PRECIPITATION TOOLS.  
 
8-14 DAY OUTLOOK FOR AUG 04 - 10 2017  
 
TODAY'S MODELS ARE IN FAIR AGREEMENT ON THE PREDICTED WEEK-2 500-HPA  
CIRCULATION PATTERN ACROSS THE FORECAST DOMAIN. TO A FIRST APPROXIMATION, THE  
EXPECTED PATTERN IS SIMILAR TO THAT FOR DAYS 6-10, BUT THERE ARE VARIOUS  
DIFFERENCES IN THE PREDICTED AMPLITUDES AND PHASES OF THE MAJOR LONG-WAVES. FOR  
EXAMPLE, MOST SOLUTIONS DEPICT A FLATTENING OF THE WESTERN CONUS RIDGE, AND  
THERE IS ALSO CONSIDERABLE UNCERTAINTY IN THE TIMING OF SHORTWAVE IMPULSES THAT  
ARE FORECAST TO CYCLE THOUGH THE LONGWAVE TROUGH ANTICIPATED OVER THE EASTERN  
BERING SEA AND THE GULF OF ALASKA. THE 0Z DETERMINISTIC GFS RUN PREDICTS A MORE  
PROGRESSIVE AND MUCH SHALLOWER TROUGH OVER THE EASTERN CONUS. THE 6Z  
DETERMINISTIC GFS RUN IS MORE PROGRESSIVE OVERALL, BRINGING TROUGH ENERGY INTO  
THE PACIFIC NORTHWEST, RIDGING INTO THE GREAT PLAINS, AND THE EASTERN CONUS  
TROUGH AXIS TO JUST OFF THE ATLANTIC SEABOARD. ENSEMBLE SPREAD IS MODERATE OVER  
MUCH OF THE FORECAST DOMAIN.  
 
THE PREDICTED WEEK-2 TEMPERATURE PATTERN IS SIMILAR TO THAT ANTICIPATED DURING  
THE 6-10 DAY PERIOD, THOUGH THERE ARE SEVERAL ADJUSTMENTS. AN INCREASE IN  
COVERAGE OF NEAR NORMAL TEMPERATURES IS INDICATED ACROSS FAR SOUTHERN ALASKA,  
INCLUDING THE PANHANDLE, DUE TO SUCH TOOLS AS THE WEEK-2 CPC TEMPERATURE  
CONSOLIDATION FORECAST, THE AUTO-BLEND TEMPERATURE TOOL, AND TO SOME EXTENT,  
THE GEFS AND ECMWF REFORECAST TEMPERATURE TOOLS. ANOTHER ADJUSTMENT MADE TO THE  
6-10 DAY TEMPERATURE OUTLOOK IS THE EXPANSION OF FAVORED ABOVE NORMAL  
TEMPERATURES ACROSS THE GREAT LAKES REGION. THIS IS DUE TO THE ANTICIPATED  
WARMING TREND IN THIS AREA. THE PRIMARY MODIFICATION MADE WITH THE  
PRECIPITATION OUTLOOK IS THE EXPANSION OF FAVORED ABOVE NORMAL PRECIPITATION  
ACROSS MOST OF THE EASTERN CONUS, THOUGH WITH MODEST PROBABILITIES. THIS IS  
BASED ON ANTICIPATED GULF MOISTURE INFLOW ACROSS THIS REGION, AND THE  
EXPECTATION OF SEVERAL COLD FRONT PASSAGES.  
 
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 20% OF TODAY'S 0Z GFS ENSEMBLE  
MEAN CENTERED ON DAY 11, 20% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY  
11, 5% OF TODAY'S OPERATIONAL 0Z GFS CENTERED ON DAY 11, 5% OF TODAY'S  
OPERATIONAL 6Z GFS CENTERED ON DAY 11, 30% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN  
CENTERED ON DAY 11, AND 20% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON  
DAY 11  
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE  
TO FAIR MODEL AGREEMENT, OFFSET BY THE PREDICTION OF VERY MODEST 500-HPA HEIGHT  
ANOMALIES AND SURFACE PRECIPITATION ANOMALIES.  
 
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 1981-2010 BASE PERIOD MEANS FOR  
TEMPERATURE...PRECIPITATION...AND 500-HPA HEIGHTS AS REFERENCE IN  
THE CLIMATE OUTLOOKS.  
 
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON  
AUGUST 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:  
19560809 - 20000810 - 19960808 - 20010809 - 19930730  
 
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:  
19960807 - 20010807 - 19560808 - 19930729 - 19860720  
 
6-10 DAY OUTLOOK TABLE  
OUTLOOK FOR AUG 02 - 06 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A B OREGON A N NRN CALIF A N  
SRN CALIF A N IDAHO A B NEVADA A N  
W MONTANA A B E MONTANA A B WYOMING A B  
UTAH A N ARIZONA A A COLORADO N N  
NEW MEXICO B N N DAKOTA A B S DAKOTA A B  
NEBRASKA N B KANSAS B B OKLAHOMA B N  
N TEXAS B A S TEXAS B A W TEXAS B A  
MINNESOTA N B IOWA N B MISSOURI B B  
ARKANSAS B N LOUISIANA B A WISCONSIN N B  
ILLINOIS N B MISSISSIPPI B A MICHIGAN N N  
INDIANA N B OHIO N N KENTUCKY N B  
TENNESSEE B N ALABAMA B A NEW YORK A N  
VERMONT A N NEW HAMP A N MAINE A N  
MASS A N CONN A B RHODE IS A B  
PENN N N NEW JERSEY A B W VIRGINIA N B  
MARYLAND N B DELAWARE A B VIRGINIA N B  
N CAROLINA N B S CAROLINA B N GEORGIA B A  
FL PNHDL N A FL PENIN A A AK N SLOPE A A  
AK ALEUTIAN A N AK WESTERN A N AK INT BSN A N  
AK S INT A N AK SO COAST A A AK PNHDL A A  
 
 
 
8-14 DAY OUTLOOK TABLE  
OUTLOOK FOR AUG 04 - 10 2017  
 
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN  
WASHINGTON A B OREGON A N NRN CALIF A N  
SRN CALIF A N IDAHO A N NEVADA A N  
W MONTANA A B E MONTANA A B WYOMING A N  
UTAH A N ARIZONA A A COLORADO B N  
NEW MEXICO B N N DAKOTA A B S DAKOTA A B  
NEBRASKA N B KANSAS B N OKLAHOMA B N  
N TEXAS B A S TEXAS N A W TEXAS B N  
MINNESOTA A B IOWA N N MISSOURI N N  
ARKANSAS B A LOUISIANA B A WISCONSIN A N  
ILLINOIS N N MISSISSIPPI B A MICHIGAN A N  
INDIANA N A OHIO N A KENTUCKY N A  
TENNESSEE N A ALABAMA B A NEW YORK A A  
VERMONT A A NEW HAMP A A MAINE A A  
MASS A A CONN A N RHODE IS A N  
PENN A A NEW JERSEY A N W VIRGINIA N A  
MARYLAND A N DELAWARE A N VIRGINIA A A  
N CAROLINA A N S CAROLINA N A GEORGIA N A  
FL PNHDL N A FL PENIN A N AK N SLOPE A A  
AK ALEUTIAN A N AK WESTERN A N AK INT BSN A N  
AK S INT A A AK SO COAST N 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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