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 May 15 2025 
 
6-10 DAY OUTLOOK FOR MAY 21 - 25 2025 
 
Today's model solutions are in good agreement on the predicted 500-hPa  
circulation pattern across North America and surrounding regions during the  
6-10 day period. The manual 500-hPa height blend is based primarily on the  
ensemble means from the GEFS, ECMWF and Canadian models due to recent model  
skill. The resultant manual blend features mid-level ridging and above-normal  
500-hPa heights over the western Contiguous United States (CONUS), while a  
mid-level trough and below-normal 500-hPa heights are forecast over most of the  
eastern CONUS. Weak troughing is also forecast across Mainland Alaska,  
extending into Southeast Alaska, while an amplified ridge and above-normal  
500-hPa heights are forecast upstream over the Bering Sea, the Aleutians and  
southwestern Mainland Alaska. Slightly below-normal  500-hPa heights are  
predicted across Hawaii. 
 
Near- to below-normal temperatures are favored over most of the central and  
eastern CONUS (except for Florida and parts of the Southern Plains, where  
above-normal temperatures are indicated) ahead of  a predicted trough and  
below-normal heights across the region. Probabilities of below-normal  
temperatures exceed 70% for portions of the Northeast. Near- to above-normal  
temperatures are favored over most of the western CONUS (except for Washington,  
where below-normal temperatures are indicated), under ridging and positive  
500-hPa height anomalies. Chances of above-normal temperatures exceeding 60% is  
likely over southwestern CONUS. Under predicted negative 500-hPa height  
anomalies, below-normal temperatures are likely over northern Alaska and  
Southeast Alaska, while slightly enhanced above-normal temperature  
probabilities are favored for parts of southern Mainland Alaska, consistent  
with the reforecast consolidation temperature tool. Above-normal temperatures  
are likely for Hawaii, with positive sea surface temperature anomalies  
surrounding the Islands. 
 
Above-normal precipitation is slightly favored for much of the northeastern  
CONUS, ahead of predicted troughing. Below-normal precipitation is favored  
across much of the western CONUS with amplified ridging predicted over the  
region. Slightly below-normal precipitation is also forecast over portions of  
the Southern Plains, Lower Mississippi Valley, and the Florida Peninsula,  
supported by most of the dynamical precipitation forecast tools. Above-normal  
precipitation is favored for most of Alaska in association with a predicted  
trough over the State. Precipitation consolidation tool forecasts favor  
above-normal precipitation for Hawaii. 
 
The official 6-10 day 500-hPa height blend consists of 30% of Today's 6z 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. Good  
agreement among the dynamical and statistical tools is offset by a progressive  
pattern. 
 
 
8-14 DAY OUTLOOK FOR MAY 23 - 29 2025  
 
Ensemble mean solutions for the 8-14 day period predict a fairly consistent  
500-hPa circulation pattern relative to the 6-10 day period across North  
America and the surrounding regions. Ensemble mean solutions for the 8-14 day  
period predict mid-level ridging and above-normal 500-hPa heights over the  
western and central CONUS, while a mid-level trough and below-normal 500-hPa  
heights are forecast over the eastern CONUS. Weak troughing continues over  
Mainland Alaska and Southeast Alaska, with an amplified anomalous ridge  
upstream over the Aleutians. Generally near- to slightly below-normal 500-hPa  
heights are forecast for Hawaii, well to the south of a mean ridge forecast  
across the eastern Pacific. 
 
Above-normal temperatures continue to be favored across most of the western  
CONUS, parts of the Southern Plains, and the Florida Peninsula in the week-2  
period, under ridging and positive 500-hPa height anomalies. Probabilities of  
above-normal temperatures exceed 50% for portions of the southwestern CONUS,  
where positive height anomalies are greatest. Below-normal temperatures are  
favored for most of the eastern CONUS under persistent troughing. Above-normal  
temperatures are favored for southern Alaska, while slightly below-normal  
temperature probabilities are indicated over parts of northern Alaska,  
consistent with most of the dynamical temperature forecast tools. Above-normal  
temperatures are favored to persist across Hawaii during week-2 by dynamical  
models. 
 
Above-normal precipitation is slightly favored for much of the northeastern  
CONUS, ahead of a predicted trough over the region. Near- to below-normal  
precipitation is slightly favored over most of the western CONUS, under mean  
positive 500-hPa height anomalies. Slightly below-normal precipitation is  
forecast over parts of the Upper Great Lakes and southeastern CONUS, while  
above-normal precipitation is predicted over portions of New Mexico, Texas,  
Colorado, Kansas, and Oklahoma, supported by most dynamical model precipitation  
forecast tools. Above-normal precipitation is favored for most of Alaska under  
persistent troughing. Above-normal precipitation is favored for Hawaii during  
the week-2 period, consistent with skill weighted calibrated precipitation  
amounts calculated from the GEFS and ECMWF ensembles. 
 
The official 8-14 day 500-hPa height blend consists of: 30% 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: Above average, 4 out of 5. Good  
agreement among the temperature and precipitation dynamical and statistical  
tools is offset by differences in ensemble mean 500-hPa height anomalies. 
 
 
FORECASTER: Luke 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 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  
June 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:  
19570425 - 19910526 - 19620516 - 19510517 - 19550522 
 
 
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:  
19570424 - 19620515 - 19590506 - 19910525 - 19720520 
 
 
6-10 DAY OUTLOOK TABLE 
Outlook for May 21 - 25 2025 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  B    N     OREGON      N    B     NRN CALIF   A    B      
SRN CALIF   A    B     IDAHO       A    B     NEVADA      A    B      
W MONTANA   N    B     E MONTANA   N    B     WYOMING     A    B      
UTAH        A    B     ARIZONA     A    B     COLORADO    A    B      
NEW MEXICO  A    N     N DAKOTA    B    N     S DAKOTA    B    B      
NEBRASKA    B    B     KANSAS      N    N     OKLAHOMA    N    N      
N TEXAS     A    B     S TEXAS     A    N     W TEXAS     A    N      
MINNESOTA   B    N     IOWA        B    N     MISSOURI    B    N      
ARKANSAS    N    N     LOUISIANA   N    B     WISCONSIN   B    N      
ILLINOIS    B    N     MISSISSIPPI N    N     MICHIGAN    B    A      
INDIANA     B    N     OHIO        B    A     KENTUCKY    B    A      
TENNESSEE   B    N     ALABAMA     N    N     NEW YORK    B    A      
VERMONT     B    A     NEW HAMP    B    A     MAINE       B    A      
MASS        B    A     CONN        B    A     RHODE IS    B    A      
PENN        B    A     NEW JERSEY  B    A     W VIRGINIA  B    A      
MARYLAND    B    A     DELAWARE    B    A     VIRGINIA    B    A      
N CAROLINA  B    A     S CAROLINA  N    A     GEORGIA     N    N      
FL PNHDL    N    N     FL PENIN    A    N     AK N SLOPE  B    A      
AK ALEUTIAN N    A     AK WESTERN  N    A     AK INT BSN  N    A      
AK S INT    N    A     AK SO COAST N    A     AK PNHDL    N    A      
  
                            
 
8-14 DAY OUTLOOK TABLE 
Outlook for May 23 - 29 2025 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  A    N     OREGON      A    B     NRN CALIF   A    B      
SRN CALIF   A    B     IDAHO       A    B     NEVADA      A    B      
W MONTANA   A    B     E MONTANA   A    N     WYOMING     A    B      
UTAH        A    B     ARIZONA     A    N     COLORADO    A    N      
NEW MEXICO  A    A     N DAKOTA    A    N     S DAKOTA    A    N      
NEBRASKA    A    N     KANSAS      A    N     OKLAHOMA    N    N      
N TEXAS     A    N     S TEXAS     A    N     W TEXAS     A    A      
MINNESOTA   N    N     IOWA        B    N     MISSOURI    B    N      
ARKANSAS    B    N     LOUISIANA   B    B     WISCONSIN   B    N      
ILLINOIS    B    N     MISSISSIPPI B    N     MICHIGAN    B    N      
INDIANA     B    N     OHIO        B    N     KENTUCKY    B    N      
TENNESSEE   B    N     ALABAMA     B    B     NEW YORK    B    A      
VERMONT     B    A     NEW HAMP    B    A     MAINE       B    A      
MASS        B    A     CONN        B    A     RHODE IS    B    A      
PENN        B    A     NEW JERSEY  B    A     W VIRGINIA  B    N      
MARYLAND    B    A     DELAWARE    B    A     VIRGINIA    B    A      
N CAROLINA  B    N     S CAROLINA  B    N     GEORGIA     B    N      
FL PNHDL    B    B     FL PENIN    A    B     AK N SLOPE  N    A      
AK ALEUTIAN A    A     AK WESTERN  A    A     AK INT BSN  N    A      
AK S INT    A    A     AK SO COAST A    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. 
 
$$