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6-10 Day outlooks are issued daily between 3pm & 4pm Eastern Time. All forecasts issued on weekends are completely automated while all weekday outlooks are modified by the forecaster.
 
Please refer to the U.S. Prognostic Discussion for an explanation of terms and symbols used on these maps.


 
 
HOME> Outlook Maps> Prognostic Map Discussion
 
Prognostic Discussions
Valid: Aug 13 - 17, 2020 (6-10 Day Outlook)
Valid: Aug 15 - 21, 2020 (8-14 Day Outlook)
Issued: Aug 07, 2020

Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks 
NWS Climate Prediction Center College Park, MD 
300 PM EDT Fri August 07 2020 
 
6-10 DAY OUTLOOK FOR AUG 13 - 17 2020 
 
Today’s model guidance is in good overall agreement on the predicted   
mid-tropospheric circulation pattern over North America and adjacent oceanic    
areas during the 6-10 day forecast period. Troughs are forecast over the  
western Aleutians as well as over Western North America from western Canada to  
the West Coast of the CONUS. Broad subtropical riding is forecast over the  
Southwest and the Southern High Plains, extending through the southeastern  
CONUS. A weakness in the subtropical ridge is noted near the western Gulf Coast Region. Ridging is forecast farther to the north over eastern Canada, favoring above normal heights from the north-central to the northeastern CONUS. Today's manual 500-hPa height blend weights the ECMWF ensemble mean slightly greater than the NCEP GEFS and Canadian ensemble means, due to recent model skill. Anomalous ridging over eastern Canada leads to enhanced probabilities of above normal temperatures for the north-central and northeastern CONUS. The greatest likelihood of above normal temperatures (greater than 70 percent) is indicated for parts of the Great Lakes and Upper Mississippi Valley where positive height anomalies are forecast to be the most pronounced. Above normal temperatures are also favored across the Great Plains and parts of the Southwest, ahead of a trough forecast over western North America. Probabilities of above normal temperatures are relatively weaker across the southeastern CONUS, due to predicted weak height anomalies and the prospect of increased cloudiness and precipitation. Below normal temperatures are likely for the northwestern CONUS extending northward to the Alaska Panhandle near the predicted mean trough axis. Enhanced probabilities of above normal temperatures are indicated for parts of western Mainland Alaska, the Alaska Peninsula, and much of the Aleutians due in large part to above normal SSTs noted in adjacent waters. The forecast position of the mean subtropical ridge over the Southwest is generally not conducive to an enhanced Monsoon. Therefore, a continuation of a dry pattern is likely across the Southwest. Enhanced probabilities of below normal precipitation extend northward across much of the Great Basin and eastward across the Central and Southern Rockies to much of the Great Plains, consistent with both ECMWF and GEFS ensemble guidance. The combination of a forecast weakness in the subtropical ridge and the potential for shortwave troughs lead to enhanced probabilities of near to above normal precipitation from the Western Gulf Coast Region and Mississippi Valley eastward to much of the Southeast and Mid-Atlantic States. Below normal precipitation is favored farther to the north, across much of the Northeast, due to predicted mean surface high pressure. There are enhanced odds of above normal precipitation from the Pacific Northwest eastward along the CONUS/Canadian Border to the Northern Plains, near and ahead of a mid-level trough predicted over western North America. A predicted 500-hPa trough over the western Aleutians and areas of surface low pressure increase chances of near to above normal precipitation across southern Alaska. Below normal precipitation is favored for much of northern Mainland Alaska, farther away from the predicted mean storm track. The official 6-10 day 500-hPa height blend consists of 10% 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 6z GFS centered on Day 8, 45% of Today's 0z European Ensemble Mean centered on Day 8, 10% of Today's operational 0z ECMWF centered on Day 8, and 10% 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 good agreement among model circulation forecasts offset by some differences among the temperature and precipitation tools. 8-14 DAY OUTLOOK FOR AUG 15 - 21 2020 During the week-2 period, model solutions begin to diverge as the ECMWF ensemble mean generally forecasts a less amplified and more progressive pattern relative to the GEFS. The predicted circulation pattern features a persistent but weakening trough over western North America from southeastern Alaska to near the west coast of the CONUS. Slightly above normal 500-hPa heights are forecast ahead of this trough from the southwestern CONUS to the Plains. Anomalous ridging is expected to persist across eastern Canada, continuing to favor above normal 500-hPa heights across the north-central and northeastern
CONUS. Slightly below normal heights are favored for the Gulf Coast Region due to a predicted weakness in the subtropical ridge. Weakly cyclonic flow and near normal heights are forecast across the Bering Sea. Slightly above normal heights are favored ahead of this trough across much of western Mainland Alaska. The ECMWF ensemble mean was weighted most in the manual blend of 500-hPa height forecasts, due to recent model skill. The 8-14 day temperature outlook is very similar to the temperature pattern forecast for the 6-10 day period. Below normal temperatures continue to be likely for parts of the northwestern CONUS, under a predicted trough and negative 500-hPa height anomalies. Above normal temperatures continue to be favored from much of the southwestern CONUS northeastward to the Northern Plains, Great Lakes and Northeast, under continued positive 500-hPs height anomalies and ridging. The region of enhanced above normal temperature probabilities is expanded west relative to the 6 to 10 day period to include most of California, as the trough over western North America is generally forecast to weaken. Below normal temperatures are likely for the Alaska Panhandle, under predicted below normal 500-hPa heights, while above normal temperatures are favored for the Aleutians and coastal southwestern Mainland Alaska in association with above normal SSTs. Above normal precipitation is likely from the Alaska Panhandle to parts of the Pacific Northwest, under a predicted mid-level trough. Near to below normal precipitation continues to be favored across most of the western and central CONUS, associated with mean ridging and consistent with ECMWF ensemble guidance. However, confidence is low across parts of the Southwest Monsoon Region as the potential for tropical activity over the Eastern Pacific may promote moisture transport into the area. Positive 500-hPa height anomalies and mean surface high pressure increase probabilities of below normal precipitation over the northeastern CONUS. Above normal precipitation probabilities are increased from the Mid-Atlantic States and Southeast westward to the Central and Western Gulf Coast Region due to a predicted weakness in the mean subtropical ridge. Above normal precipitation probabilities are also enhanced for parts of the Upper Mississippi Valley and Great Lakes underneath mean southerly low-level flow. Below normal precipitation is likely for much of northern Mainland Alaska, consistent with guidance from the GEFS and ECMWF ensembles. The official 8-14 day 500-hPa height blend consists of: 15% of Today's 0z GFS Ensemble Mean centered on Day 11, 15% of Today's 6z GFS Ensemble 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: Average, 3 out of 5, due to good overall forecast consistency with the preceding 6 to 10 day period offset by increasing model differences between the ECMWF and GEFS ensemble solutions. FORECASTER: Scott 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 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 20. 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: 19700720 - 19920805 - 19800814 - 20030815 - 19920815 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: 19700720 - 19970718 - 19820809 - 19920804 - 19930815 6-10 DAY OUTLOOK TABLE Outlook for Aug 13 - 17 2020 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B A OREGON B A NRN CALIF N N SRN CALIF N N IDAHO B A NEVADA B B W MONTANA B A E MONTANA B N WYOMING B B UTAH B B ARIZONA A B COLORADO A B NEW MEXICO A B N DAKOTA A A S DAKOTA A N NEBRASKA A B KANSAS A B OKLAHOMA A B N TEXAS A B S TEXAS A N W TEXAS A B MINNESOTA A A IOWA A A MISSOURI A A ARKANSAS N A LOUISIANA N A WISCONSIN A A ILLINOIS A A MISSISSIPPI N A MICHIGAN A A INDIANA A A OHIO A A KENTUCKY A A TENNESSEE A A ALABAMA A A 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 A NEW JERSEY A N W VIRGINIA A A MARYLAND A A DELAWARE A A VIRGINIA A A N CAROLINA N A S CAROLINA N A GEORGIA A A FL PNHDL A N FL PENIN A N AK N SLOPE N B AK ALEUTIAN A N AK WESTERN A B AK INT BSN N B AK S INT N N AK SO COAST N N AK PNHDL B A 8-14 DAY OUTLOOK TABLE Outlook for Aug 15 - 21 2020 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B A OREGON N N NRN CALIF A N SRN CALIF A B IDAHO B B NEVADA N B W MONTANA B N E MONTANA B B WYOMING B B UTAH A B ARIZONA A B COLORADO A B NEW MEXICO A B N DAKOTA A N S DAKOTA A B NEBRASKA A B KANSAS A B OKLAHOMA N B N TEXAS N B S TEXAS A A W TEXAS A B MINNESOTA A A IOWA A N MISSOURI A N ARKANSAS N A LOUISIANA N A WISCONSIN A A ILLINOIS A A MISSISSIPPI N A MICHIGAN A A INDIANA A A OHIO A A KENTUCKY A A TENNESSEE N A ALABAMA N A 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 A NEW JERSEY A N W VIRGINIA A A MARYLAND A N DELAWARE A N VIRGINIA A A N CAROLINA N A S CAROLINA N A GEORGIA A A FL PNHDL A N FL PENIN A N AK N SLOPE N B AK ALEUTIAN A N AK WESTERN A B AK INT BSN N B AK S INT N N AK SO COAST A 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. $$
 
Related Topics:
Prognostic Discussion, Surface Forecasts, 500mb Heights and Anomalies, Time Series of Surface Forecast Skill, Model Guidance Used Our Mission, Who We Are, CPC Information, CPC Web Team
 

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