NWS Climate Prediction Center



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Latest 6 to 10 Day Temperature Outlook

Prognostic Discussions


Valid: Sep 27 - Oct 01, 2018 (6-10 Day Outlook)
Valid: Sep 29 - Oct 05, 2018 (8-14 Day Outlook)
Issued: Sep 21, 2018


PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS 
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD 
300 PM EDT FRI SEPTEMBER 21 2018 
 
6-10 DAY OUTLOOK FOR SEP 27 - OCT 01, 2018 
 
TODAY'S MODELS ARE IN GENERALLY GOOD AGREEMENT ON THE OVERALL 500-HPA  
GEOPOTENTIAL HEIGHT PATTERN FORECAST DURING THE 6-10 DAY PERIOD. A DEEP TROUGH  
IS FORECAST OVER THE BERING SEA, WHILE A STRONG, VERY ANOMALOUS RIDGE IS  
FORECAST OVER MAINLAND ALASKA AND ALONG THE WEST COAST OF THE CONUS. DOWNSTREAM  
A DEEP LONG-WAVE TROUGH IS CENTERED OVER PARTS OF THE UPPER MIDWEST AND WESTERN  
GREAT LAKES REGION, AND SOME RIDGING IS FORECAST TO PERSIST OVER PARTS OF THE  
SOUTHEAST. TODAY'S 0Z ECMWF DETERMINISTIC MODEL IS PREDICTING A SIGNIFICANTLY  
DIFFERENT PATTERN THAN THE REST OF THE MODELS OVER THE CONUS, WITH ANOMALOUS  
TROUGHING OVER MUCH OF WESTERN CONUS AND ANOMALOUS RIDGING FOR THE EASTERN HALF  
OF THE CONUS. SINCE THIS MODEL IS CURRENTLY AN OUTLIER IT WASN'T CONSIDERED IN  
THE MANUAL 500-HPA BLEND. HOWEVER THIS PATTERN DOES AGREE WITH TELECONNECTIONS  
BASED ON THE ANOMALOUS RIDGE OVER ALASKA, SO IT MAY BE HINTING AT AN UPCOMING  
PATTERN SHIFT OVER THE NEXT FEW DAYS OF MODEL RUNS. 
 
LARGE POSITIVE HEIGHT ANOMALIES OVER ALASKA STRONGLY FAVOR ABOVE NORMAL  
TEMPERATURES FOR THE ENTIRE STATE. THESE POSITIVE HEIGHT ANOMALIES EXTEND SOUTH  
OVER MUCH OF THE WESTERN CONUS, FAVORING ABOVE NORMAL TEMPERATURES FOR PARTS OF  
THE WESTERN CONUS. COLD AIR ADVECTION BENEATH A PREDICTED ANOMALOUSLY DEEP  
TROUGH STRONGLY FAVORS BELOW NORMAL TEMPERATURES OVER THE CENTRAL U.S., MOST LIKELY IN THE NORTHERN PLAINS WHERE MODELS AND TOOLS HAVE THE BEST AGREEMENT, AND WHERE BELOW NORMAL TEMPERATURES ARE FORECAST TO BE THE MOST PERSISTENT. AHEAD OF THE TROUGH, ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE EASTERN SEABOARD. THE STRONG RIDGE PREDICTED OVER THE WESTERN U.S. INCREASES THE LIKELIHOOD OF NEAR TO BELOW NORMAL PRECIPITATION FOR THE WESTERN CONUS AND THE ALASKA PANHANDLE. SEVERAL STORM SYSTEMS ARE FORECAST TO TRACK INTO ALASKA AND OVER THIS RIDGE, ENHANCING THE LIKELIHOOD OF ABOVE NORMAL PRECIPITATION FOR MOST OF ALASKA. A COUPLE OF FRONTAL PASSAGES IN THE EASTERN CONUS INCREASE THE CHANCES OF ABOVE NORMAL PRECIPITATION FOR THE EASTERN HALF OF THE U.S., ESPECIALLY OVER PARTS OF TEXAS AND LOUISIANA WHERE PRECIPITATION IS EXPECTED TO PERSIST ALONG A STALLED FRONTAL BOUNDARY. THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 30% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 30% OF TODAY'S OPERATIONAL 0Z GFS CENTERED ON DAY 8, AND 40% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8 FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: WELL ABOVE AVERAGE, 5 OUT OF 5, DUE TO GOOD AGREEMENT AMONG THE MODELS AND TOOLS AND A WELL-DEFINED HIGHLY AMPLIFIED PATTERN. 8-14 DAY OUTLOOK FOR SEP 29 - OCT 05, 2018 DURING THE WEEK-2 PERIOD MODELS ARE PREDICTING A SIMILAR PATTERN TO THE 6-10 DAY PERIOD, WITH THE TROUGH OVER THE CONUS SHIFTED SLIGHTLY EASTWARD. 500-HPA
ANOMALIES ARE SMALLER OVER THE ENTIRE FORECAST DOMAIN, DUE TO INCREASED UNCERTAINTY. THIS IS ESPECIALLY TRUE OVER THE CONUS, WHERE SOME MODELS ARE HINTING AT A PATTERN CHANGE THAT WOULD INTRODUCE SOME TROUGHING INTO THE WESTERN CONUS AND RIDGING INTO THE EASTERN CONUS. TODAY'S WEEK-2 500-HPA BLEND DOES NOT INCLUDE ANY DETERMINISTIC MODELS, DUE TO THEIR POOR RUN-TO-RUN CONTINUITY. THE TEMPERATURE PROBABILITY FORECAST FOR WEEK-2 IS SIMILAR TO THE 6-10 DAY PERIOD, EXCEPT THE PROBABILITIES OF BELOW NORMAL TEMPERATURES ARE SHIFTED EASTWARD, LEAVING ONLY COASTAL AREAS OF THE SOUTHEASTERN CONUS AND FLORIDA WITH FAVORED ABOVE NORMAL TEMPERATURES IN WEEK-2. THE PRECIPITATION PROBABILITY FORECAST FOR WEEK-2 IS ALSO SIMILAR TO THE 6-10 DAY PERIOD, WITH A COUPLE OF EXCEPTIONS. THE PROBABILITIES OF ABOVE NORMAL PRECIPITATION OVER THE CONUS ARE SHIFTED SLIGHTLY EAST AS THE TROUGH SHIFTS EASTWARD, AND NEAR NORMAL PRECIPITATION IS FAVORED OVER PARTS OF THE FOUR CORNERS REGION DUE TO SOME TOOLS INTRODUCING SOME PRECIP INTO THE AREA TOWARDS THE END OF THE WEEK-2 PERIOD. THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 40% OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 11, AND 60% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11 FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO FAIRLY GOOD AGREEMENT AMONG THE MODELS AND TEMPERATURE TOOLS AND A WELL-DEFINED HIGHLY AMPLIFIED PATTERN, OFFSET SLIGHTLY BY SOME DIFFERENCES BETWEEN THE PRECIPITATION TOOLS. FORECASTER: MIKE C 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 OCTOBER 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: 19831005 - 19720918 - 19960929 - 20001001 - 19731004
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: 19720917 - 20001001 - 19731002 - 19831004 - 19800921 6-10 DAY OUTLOOK TABLE OUTLOOK FOR SEP 27 - OCT 01, 2018 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON A B OREGON A B NRN CALIF A N SRN CALIF A N IDAHO B B NEVADA A B W MONTANA B N E MONTANA B A WYOMING B N UTAH A B ARIZONA A N COLORADO B B NEW MEXICO A N N DAKOTA B A S DAKOTA B A NEBRASKA B A KANSAS B A OKLAHOMA B A N TEXAS B A S TEXAS N A W TEXAS B A MINNESOTA B A IOWA B A MISSOURI B A ARKANSAS B A LOUISIANA N A WISCONSIN B A ILLINOIS B A MISSISSIPPI A A MICHIGAN B A INDIANA B A OHIO B A KENTUCKY B A TENNESSEE N A ALABAMA A A NEW YORK N A VERMONT N A NEW HAMP A A MAINE A A MASS A A CONN A A RHODE IS A A PENN N A NEW JERSEY A A W VIRGINIA N 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 A A AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A AK S INT A A AK SO COAST A A AK PNHDL A B 8-14 DAY OUTLOOK TABLE OUTLOOK FOR SEP 29 - OCT 05, 2018 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON A B OREGON A B NRN CALIF A N SRN CALIF A N IDAHO N N NEVADA A N W MONTANA B N E MONTANA B N WYOMING B N UTAH A N ARIZONA A N COLORADO A N NEW MEXICO A N N DAKOTA B N S DAKOTA B N NEBRASKA B A KANSAS B A OKLAHOMA B A N TEXAS B A S TEXAS B A W TEXAS B A MINNESOTA B A IOWA B A MISSOURI B A ARKANSAS B A LOUISIANA B A WISCONSIN B A ILLINOIS B A MISSISSIPPI B A MICHIGAN B A INDIANA B A OHIO B A KENTUCKY B A TENNESSEE B A ALABAMA N A NEW YORK B 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 N A W VIRGINIA B A MARYLAND B A DELAWARE N A VIRGINIA B A N CAROLINA N A S CAROLINA A A GEORGIA A A FL PNHDL A A FL PENIN A A AK N SLOPE A A AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A AK S INT A A AK SO COAST A 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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