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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: Oct 01 - 05, 2023 (6-10 Day Outlook)
Valid: Oct 03 - 09, 2023 (8-14 Day Outlook)
Issued: Sep 25, 2023

Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks 
NWS Climate Prediction Center College Park, MD 
300 PM EDT Mon September 25 2023 
 
6-10 DAY OUTLOOK FOR OCT 01 - 05 2023 
 
The GEFS, Canadian, and ECMWF ensemble means are in good agreement predicting  
an amplified 500-hPa ridge over southwestern Alaska and the Bering Sea. A  
trough is predicted over the western contiguous U.S. (CONUS) in the GEFS, ECMWF  
and Canadian ensemble means that de-amplifies during the period. Ensemble mean  
solutions are in good agreement predicting a persistent amplified ridge over  
the eastern CONUS.  
 
Below normal temperatures are favored over most of Alaska, excluding western  
and northern Alaska, under anomalous northerly flow to the east of the  
predicted amplified ridge. Below normal temperatures are favored for most of  
the western CONUS, under a mean trough and weak negative 500-hPa height  
anomalies. Above normal temperatures are likely for the central and eastern CONUS under an amplified ridge. Prevailing southerly surface flow along with a ridge aloft results in large probabilities of more than 80 percent for above normal temperatures across the Upper Mississippi Valley. Above normal precipitation is favored for northern Mainland Alaska, while below normal precipitation is favored for southern Mainland Alaska, under anomalous northerly flow ahead of the predicted ridge. Above normal precipitation is favored for the northern half of the West, ahead of a predicted trough, and over much of the Great Plains region in the central CONUS, with predicted surface southerly flow. Below normal precipitation is likely for most of the eastern CONUS, under the predicted ridge. Above normal precipitation is slightly favored for the Florida Peninsula, with a storm system potentially passing just east of this region. The official 6-10 day 500-hPa height blend consists of 30% of Today's 0z GFS Ensemble Mean centered on Day 8, 40% 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 good agreement on an amplified mid-level height pattern over North America and fairly good agreement among the tools. 8-14 DAY OUTLOOK FOR OCT 03 - 09 2023 Model forecasts continue to predict a ridge over southwest Alaska in week-2. The GEFS and Canadian ensemble means show somewhat less amplified positive 500-hPa height anomalies over the region than the ECMWF ensemble mean. The ECMWF ensemble mean forecast was favored in today‚Äôs manual blend of 500-hPa height forecasts, due to recent greater anomaly correlation">anomaly correlation to observations than the GEFS and Canadian ensemble means. The GEFS, ECMWF, and Canadian ensemble means agree in predicting a more zonal flow pattern over the CONUS, at the start of the week-2 period, with the development of a trough along the western CONUS later in the period. The manual blend of model 500-hPa height forecasts predicts a trough axis slightly further west in the 8-14 day period than in the 6-10 day period. A ridge and positive 500-hPa height anomalies persist over the eastern CONUS during week-2. Below normal temperatures continue to be favored over interior and southeastern Alaska during week-2, under anomalous northerly flow, while above normal temperatures are favored for western Mainland Alaska and the Aleutians, under the positive 500-hPa height anomaly center. Below normal temperatures are favored over most of the western third of the CONUS under a predicted trough. Above normal temperatures continue to be likely for the eastern two-thirds of the CONUS under an amplified ridge. Above normal precipitation is favored for central and northern areas of Alaska, under anomalous northwesterly flow, while near to below normal precipitation is favored for southern areas of the state. Above normal precipitation is favored for most of the western CONUS, outside climatologically dry areas of the Southwest, ahead of a predicted trough. Below normal precipitation is favored from the Tennessee Valley to the Northeast, under the predicted ridge. There is greater uncertainty for the precipitation forecast for the Southeast, where near normal precipitation is favored. The official 8-14 day 500-hPa height blend consists of: 30% of Today's 0z 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 agreement on the 500-hPa height pattern in week-2, offset by increasing uncertainty in temperature and precipitation tools. FORECASTER: D Collins 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 October 19. 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: 20071009 - 20010927 - 19620930 - 20081006 - 19870918 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: 20010926 - 19620929 - 20071008 - 19621004 - 19870917 6-10 DAY OUTLOOK TABLE Outlook for Oct 01 - 05 2023 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B A OREGON B A NRN CALIF B N SRN CALIF B N IDAHO B A NEVADA B A W MONTANA B A E MONTANA N A WYOMING B A UTAH B A ARIZONA B 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 A B S TEXAS A N W TEXAS A A MINNESOTA A A IOWA A A MISSOURI A B ARKANSAS A B LOUISIANA A B WISCONSIN A N ILLINOIS A B MISSISSIPPI A B MICHIGAN A B INDIANA A B OHIO A B KENTUCKY A B TENNESSEE A B ALABAMA A B 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 A B DELAWARE A B VIRGINIA A B N CAROLINA A B S CAROLINA A B GEORGIA A B FL PNHDL A N FL PENIN N N AK N SLOPE N A AK ALEUTIAN N B AK WESTERN N N AK INT BSN B A AK S INT B B AK SO COAST B B AK PNHDL B N 8-14 DAY OUTLOOK TABLE Outlook for Oct 03 - 09 2023 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B A OREGON B A NRN CALIF B A SRN CALIF B N IDAHO B A NEVADA B N W MONTANA B A E MONTANA B A WYOMING B A UTAH B A ARIZONA B 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 A A S TEXAS A A W TEXAS A A MINNESOTA A A IOWA A A MISSOURI A A ARKANSAS A A LOUISIANA A A WISCONSIN A A ILLINOIS A A MISSISSIPPI A N MICHIGAN A N INDIANA A N OHIO A B KENTUCKY A B TENNESSEE A B ALABAMA A 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 A B DELAWARE A N VIRGINIA A B N CAROLINA A N S CAROLINA A N GEORGIA A N FL PNHDL A N FL PENIN A N AK N SLOPE N A AK ALEUTIAN A N AK WESTERN A A AK INT BSN B A AK S INT B N AK SO COAST B N AK PNHDL B 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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