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 Wed May 07 2025 
 
6-10 DAY OUTLOOK FOR MAY 13 - 17 2025 
 
Today's ensemble mean solutions are in good agreement in depicting a high  
amplitude 500-hPa pattern across much of North America. The period begins with  
anomalous troughing over the Davis Strait extending southward to offshore of  
Atlantic Canada. A strong anomalous ridge is forecast across the Great Lakes  
and a trough or closed low is predicted to undercut this ridge over the  
Southeast. Across western North America and the Eastern Pacific, three main  
features are forecast to dominate, the first two features being a pair of  
troughs located over the eastern Bering Sea and near or just inland of the west  
coast of the Contiguous United States (CONUS). Ridging is forecast in between  
these two troughs well offshore of the Pacific Northwest. The pattern for  
Alaska is forecast to be slow-moving such that by the end of the period, the  
trough over the Bering Sea is predicted to essentially remain in place. The  
downstream trough near the West Coast is forecast to move across the Interior  
West and eventually to the Northern Plains by day 10. The anomalous ridge over  
the Great Lakes is forecast to drift eastward and slowly weaken. Finally, the  
trough or closed low over the Southeast is predicted to slowly lift  
northeastward to the Mid-Atlantic then move offshore by the middle or end of  
the period. 
 
Above normal temperatures are likely for most of the CONUS east of the Rockies  
due to a combination of anomalous ridging over the Great Lakes and southerly  
flow across the Plains and Mississippi Valley. The highest likelihood of  
unseasonable warmth is across the central and eastern Great Lakes, near the  
center of the predicted mean ridge. However, near normal temperatures are more  
likely for the coastal Southeast and southern Mid-Atlantic as a predicted storm  
system significantly reduces chances of anomalous warmth. Below normal  
temperatures are likely for the western CONUS as a strong trough is forecast to  
progress eastward across the region during the period. A slight tilt toward  
above normal temperatures is indicated for southwestern Alaska ahead of the  
Bering Sea trough. Above normal sea surface temperatures (SSTs) in nearby  
waters may also contribute to increasing chances of above normal temperatures  
for this region. Below normal temperatures are slightly favored for parts of  
eastern Mainland Alaska consistent with predicted below normal heights and for  
Southeast Alaska underneath anomalous northerly mid-level flow. Near normal  
temperatures are favored for the remainder of the state due to weak or  
conflicting guidance. Above normal temperatures are likely across Hawaii  
consistent with anticipated above normal sea surface temperatures (SSTs) in  
adjacent waters.  
 
An active period is anticipated across much of the western CONUS as an  
anomalous trough pushes inland from the Pacific during the period. As the  
trough progresses eastward, enhanced above normal precipitation probabilities  
are forecast across much of the West and eventually farther to the east across  
the Northern and Central Plains and Upper and Middle Mississippi Valley as  
southerly flow increases. Above normal precipitation is also likely for the  
coastal Southeast and Mid-Atlantic as a slow moving low pressure system is  
expected to promote ample moisture advection into this region from the Gulf and  
Atlantic. In between these two active regions, near to below normal  
precipitation is more likely across parts of the Southern Plains, the Lower  
Mississippi Valley, the Ohio Valley, the central and eastern Great Lakes, and  
much of the Northeast. Conversely, above normal precipitation is favored across  
most of southern and central Alaska due to persistent anomalous troughing  
predicted over the Bering Sea. Above normal precipitation is also favored for  
Hawaii, consistent with skill weighted calibrated precipitation amounts  
calculated from the GEFS and ECMWF ensembles. 
 
The official 6-10 day 500-hPa height blend consists of 20% of Today's 6z GFS  
Ensemble Mean centered on Day 8, 50% 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 among today’s ensemble means. 
 
 
8-14 DAY OUTLOOK FOR MAY 15 - 21 2025  
 
The week-2 period begins with a highly amplified pattern featuring anomalous  
ridging over the Great Lakes and troughs near the East Coast, the interior  
West, the Northern Plains, and eastern Bering Sea. The trough over the Bering  
Sea is forecast to gradually reduce in intensity. The trough over the Northern  
Plains is forecast to progress eastward and weaken with time. The trough over  
the Interior West is also forecast to weaken significantly with models  
indicating a potential retrogression back toward the West Coast near the end of  
the period. The ridge over the Great Lakes is generally forecast to lift  
northeastward with heights returning to near normal in its wake across much of  
the East during the latter half of the period. Farther to the west, increased  
ridging is predicted across the Southern High Plains by the end of the period.  
Generally near normal 500-hPa heights are forecast for Hawaii, well to the  
south of a mean ridge forecast across the eastern Pacific.  
 
Above normal temperatures are favored for most of the CONUS east of the  
Mississippi and for much of the Southern Plains. This is especially true for  
the eastern Gulf Coast Region northeastward to the eastern Great Lakes due to a  
combination of anomalous ridging and southerly flow. However, relatively  
modestly enhanced probabilities of above normal temperatures are indicated for  
the Northeast and Mid-Atlantic coast as confidence is tempered in the wake of a  
departing low pressure system early in the period. Cooler than normal  
temperatures are favored for most of the western third of the CONUS due to  
strong troughing, particularly early in the period. However, near normal  
temperatures are more likely for much of northern and central California and  
adjacent southwestern Oregon as 500-hPa heights are forecast to moderate by the  
middle of the period. Near normal temperatures are also favored for most of  
Alaska due to weak or conflicting guidance. However a slight tilt toward below  
normal temperatures are indicated for a small portion of northeastern Alaska  
associated with nearby Arctic surface high pressure to the north. Above normal  
temperatures remain likely across Hawaii associated with anticipated above  
normal SSTs in adjacent waters. 
 
An active pattern is anticipated to continue into week-2 for much of the  
Interior West (with the exception of climatologically dry areas of the  
Southwest) due to a predicted trough early in the period. Farther to the east,  
an active pattern is favored for much of the north-central CONUS as surface low  
pressure is forecast to be well established by the beginning of the period. As  
this surface low progresses northeast, increased southerly flow promotes  
increased chances of above normal precipitation southward to the central Plains  
and northern portions of the southern Plains and eastward to the northern  
two-thirds of the Mississippi Valley. Below normal precipitation is more likely  
across the Southeast as surface high pressure develops behind a departing low  
off the coast. An active pattern and increased above normal precipitation  
chances remain forecast for much of southern and central Alaska due to  
persistent troughing over the Bering Sea. Above normal precipitation is also  
favored for Hawaii, 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: 20% of Today's 6z GFS  
Ensemble Mean centered on Day 11, 50% 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 a  
predicted amplified pattern early in period offset by a potential moderation of  
the pattern and increased uncertainty later in week-2. 
 
 
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 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:  
19880521 - 19570428 - 19870421 - 19780516 - 19700503 
 
 
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:  
19780516 - 19870421 - 19700502 - 20060426 - 19570427 
 
 
6-10 DAY OUTLOOK TABLE 
Outlook for May 13 - 17 2025 
 
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    A      
W MONTANA   B    A     E MONTANA   N    A     WYOMING     B    A      
UTAH        B    A     ARIZONA     B    N     COLORADO    B    A      
NEW MEXICO  B    N     N DAKOTA    A    A     S DAKOTA    A    A      
NEBRASKA    A    A     KANSAS      A    A     OKLAHOMA    A    A      
N TEXAS     A    N     S TEXAS     A    B     W TEXAS     A    N      
MINNESOTA   A    A     IOWA        A    A     MISSOURI    A    A      
ARKANSAS    A    N     LOUISIANA   A    B     WISCONSIN   A    A      
ILLINOIS    A    N     MISSISSIPPI A    B     MICHIGAN    A    N      
INDIANA     A    N     OHIO        A    N     KENTUCKY    A    N      
TENNESSEE   A    N     ALABAMA     A    B     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    A     NEW JERSEY  A    A     W VIRGINIA  A    A      
MARYLAND    A    A     DELAWARE    A    A     VIRGINIA    A    A      
N CAROLINA  A    A     S CAROLINA  N    A     GEORGIA     N    A      
FL PNHDL    N    N     FL PENIN    N    A     AK N SLOPE  N    N      
AK ALEUTIAN A    A     AK WESTERN  N    A     AK INT BSN  N    A      
AK S INT    N    A     AK SO COAST N    A     AK PNHDL    B    A      
  
                            
 
8-14 DAY OUTLOOK TABLE 
Outlook for May 15 - 21 2025 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  B    N     OREGON      B    N     NRN CALIF   N    N      
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    B    A      
NEW MEXICO  B    N     N DAKOTA    N    A     S DAKOTA    N    A      
NEBRASKA    N    A     KANSAS      A    A     OKLAHOMA    A    A      
N TEXAS     A    N     S TEXAS     A    N     W TEXAS     A    N      
MINNESOTA   N    A     IOWA        A    A     MISSOURI    A    A      
ARKANSAS    A    A     LOUISIANA   A    N     WISCONSIN   A    A      
ILLINOIS    A    A     MISSISSIPPI A    N     MICHIGAN    A    A      
INDIANA     A    A     OHIO        A    N     KENTUCKY    A    N      
TENNESSEE   A    N     ALABAMA     A    B     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    N     VIRGINIA    A    N      
N CAROLINA  A    B     S CAROLINA  A    B     GEORGIA     A    B      
FL PNHDL    A    B     FL PENIN    A    B     AK N SLOPE  N    N      
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      
  
                           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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