Climate Prediction Center - 6-10 and 8-14 Day Prognostic Discussions

Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks 
NWS Climate Prediction Center College Park, MD 
300 PM EDT Thu April 24 2025 
 
6-10 DAY OUTLOOK FOR APR 30 - MAY 04, 2025 
 
Model ensemble means (GEFS, ECMWF, and Canadian) are in good agreement with a  
progressive flow pattern over the Contiguous U.S. (CONUS) from the end of April  
through the beginning of May. A 500-hPa trough is forecast to shift eastward  
from the Great Plains to the eastern CONUS, while an amplified mid-level ridge  
progresses across the West and is centered across the Northern Great Plains by  
day 10. For this 5-day period, the manual 500-hPa height blend depicts positive  
500-hPa height anomalies for nearly all of the CONUS and an increased chance of  
above-normal temperatures for most areas. A trough continues to be forecast  
across western Alaska and extending into the Gulf of Alaska in the 6-10 day  
period, with associated negative 500-hPa height anomalies across the state.  
 
Above-normal temperature probabilities exceed 70 percent for the northern High  
Plains, under the center of a predicted ridge. Anomalous positive temperature  
anomalies are predicted over the southeastern CONUS for the first half of the  
6-10 day forecast period. Near to below-normal temperatures are forecast over  
northeastern areas of the CONUS, under the predicted trough that progresses  
over the East during the period. Near normal temperatures are favored for parts  
of the Southwest and Southern Great Plains due to lower 500-hPa heights and  
increasing probabilities of precipitation. Below-normal temperatures are likely  
for much of northern Alaska under predicted negative 500-hPa height anomalies.  
Near-normal temperatures are favored for southern Mainland Alaska and Southeast  
Alaska, under southerly mid-level flow. Above-normal temperatures are likely  
for Hawaii, with positive surrounding sea surface temperature anomalies.  
 
Above-normal precipitation is favored across southern and central Mainland  
Alaska with probabilities exceeding 50 percent for Southeast Alaska, ahead of a  
predicted trough and southerly flow. With the progressive mid-level circulation  
pattern forecast for the CONUS, above-normal precipitation is favored across  
most of the southern CONUS. Increasing chances of above-normal precipitation  
are forecast for the southwestern CONUS with a shortwave trough moving into the  
Southwest during the period. Probabilities for above-normal precipitation  
exceed 50 percent for parts of the Southern Plains. Above-normal precipitation  
is favored for the entire East Coast, with the passage of a front.  
Near-to-below normal precipitation is favored across much of the northern  
CONUS, under the developing ridge. Dynamical model forecasts favor above-normal  
precipitation for Hawaii.  
 
The official 6-10 day 500-hPa height blend consists of 25% of Today's 0z GFS  
Ensemble Mean centered on Day 8, 40% of Today's 0z European Ensemble Mean  
centered on Day 8, and 35% 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 model agreement on the progressive circulation pattern, offset by some  
areas of disagreement among forecast tools.  
 
8-14 DAY OUTLOOK FOR MAY 02 - 08 2025  
 
Ensemble means forecast a continued progressive pattern during the week-2  
period. A predicted ridge amplifies over the northern central CONUS during the  
period and positive 500-hPa height anomalies are forecast across the Northeast  
after the passage of a trough. A trough and associated negative 500-hPa height  
anomalies persist across Alaska and extend southward along the west coast of  
North America later in the period.  
 
Above-normal temperatures continue to be favored across most of the CONUS in  
the week-2 period. Probabilities exceed 70 percent for parts of the Northern  
Plains as the ridge amplifies over this region. Above-normal temperatures are  
slightly favored for much of the East under mean positive 500-hPa height  
anomalies. Near to below-normal temperatures are favored for parts of the  
Southwest, Southern Plains, and Lower Mississippi Valley, with predicted  
near-average mid-level heights and enhanced precipitation. Below-normal  
temperatures are favored for northwestern and northern Mainland Alaska under  
negative 500-hPa height anomalies. Above-normal temperatures are predicted to  
persist across Hawaii during week-2.  
 
Similar to the 6-10 day period, above-normal precipitation is favored for most  
of Mainland Alaska, excluding the west and north coasts, and favored for  
Southeast Alaska, ahead of predicted troughs. Above-normal precipitation  
continues to be favored for much of the southwestern CONUS into the Southern  
Plains, with a predicted trough developing over the region. Above-normal  
precipitation is also favored for the Gulf and southern Atlantic coasts,  
supported by most dynamical model forecast tools. Dynamical models continue to  
predict favored above-normal precipitation for Hawaii during the week-2 period.  
 
The official 8-14 day 500-hPa height blend consists of: 25% of Today's 0z GFS  
Ensemble Mean centered on Day 11, 40% of Today's 0z European Ensemble Mean  
centered on Day 11, and 35% of Today's 0z Canadian Ensemble Mean centered on  
Day 11  
 
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: About average, 3 out of 5, due to  
good agreement among the mean dynamical model height forecasts and surface  
tools for most areas, offset by uncertainty due to an evolving pattern. 
 
FORECASTER: Dan 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 May  
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:  
19540422 - 19810407 - 20020420 - 20080416 - 19640420 
 
 
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:  
20020421 - 19540419 - 19810407 - 20080415 - 20020416 
 
 
6-10 DAY OUTLOOK TABLE 
Outlook for Apr 30 - May 04, 2025 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  A    N     OREGON      A    N     NRN CALIF   A    N      
SRN CALIF   A    A     IDAHO       A    N     NEVADA      A    A      
W MONTANA   A    N     E MONTANA   A    N     WYOMING     A    N      
UTAH        A    A     ARIZONA     A    A     COLORADO    A    A      
NEW MEXICO  A    A     N DAKOTA    A    N     S DAKOTA    A    N      
NEBRASKA    A    N     KANSAS      A    A     OKLAHOMA    N    A      
N TEXAS     A    A     S TEXAS     A    A     W TEXAS     N    A      
MINNESOTA   A    N     IOWA        A    N     MISSOURI    A    A      
ARKANSAS    A    A     LOUISIANA   A    A     WISCONSIN   N    N      
ILLINOIS    N    N     MISSISSIPPI A    A     MICHIGAN    B    N      
INDIANA     N    N     OHIO        N    A     KENTUCKY    A    A      
TENNESSEE   A    A     ALABAMA     A    A     NEW YORK    N    N      
VERMONT     N    N     NEW HAMP    N    N     MAINE       N    A      
MASS        N    A     CONN        A    A     RHODE IS    A    A      
PENN        A    A     NEW JERSEY  A    A     W VIRGINIA  A    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  B    N      
AK ALEUTIAN B    A     AK WESTERN  B    A     AK INT BSN  B    A      
AK S INT    N    A     AK SO COAST N    A     AK PNHDL    N    A      
  
                            
 
8-14 DAY OUTLOOK TABLE 
Outlook for May 02 - 08 2025 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  A    N     OREGON      A    N     NRN CALIF   A    N      
SRN CALIF   A    A     IDAHO       A    N     NEVADA      A    A      
W MONTANA   A    N     E MONTANA   A    N     WYOMING     A    N      
UTAH        A    A     ARIZONA     A    A     COLORADO    A    A      
NEW MEXICO  A    A     N DAKOTA    A    N     S DAKOTA    A    N      
NEBRASKA    A    N     KANSAS      A    A     OKLAHOMA    N    A      
N TEXAS     N    A     S TEXAS     N    A     W TEXAS     B    A      
MINNESOTA   A    N     IOWA        A    N     MISSOURI    A    N      
ARKANSAS    N    N     LOUISIANA   A    A     WISCONSIN   A    N      
ILLINOIS    A    N     MISSISSIPPI N    A     MICHIGAN    A    N      
INDIANA     A    N     OHIO        A    N     KENTUCKY    A    N      
TENNESSEE   N    N     ALABAMA     N    N     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    A     VIRGINIA    A    N      
N CAROLINA  A    A     S CAROLINA  A    A     GEORGIA     A    A      
FL PNHDL    A    A     FL PENIN    N    A     AK N SLOPE  B    N      
AK ALEUTIAN B    N     AK WESTERN  B    N     AK INT BSN  B    A      
AK S INT    N    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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