Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks 
NWS Climate Prediction Center College Park, MD 
300 PM EDT Fri May 17 2024 
 
6-10 DAY OUTLOOK FOR MAY 23 - 27 2024 
 
Today's model solutions are in good agreement on the predicted amplified  
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 negative 500-hPa height anomalies  
over much of the western and north-central contiguous U.S. (CONUS). Positive  
height anomalies are forecast over the southern tier of the CONUS. These  
positive height anomalies are associated with a subtropical ridge. Over the  
Alaska domain, a weak trough is depicted over the Bering Sea and western  
Mainland, while mid-level ridging is forecast over the Aleutians.This mid-level  
ridging represents the northeastern extent of a broad, zonally elongated  
anomalous ridge that is predicted over much of the North Pacific. A weak  
mid-level trough is anticipated over the Hawaiian Islands. 
 
Negative 500-hPa height anomalies and mid-level troughing over the western  
CONUS favor below-normal temperatures over the western and north-central CONUS  
eastward into the Great Lakes region. Enhanced chances for above-normal  
temperatures are predicted over much of the south-central and eastern CONUS due  
to subtropical ridging and above-normal 500-hPa height anomalies, supported by  
most of the dynamical temperature forecast tools. Probabilities favoring above  
normal temperatures exceed 80% for portions of South Texas. In Alaska,  
below-normal temperature chances are increased over much of the central and  
western Mainland Alaska and the adjacent Alaska Peninsula associated with the  
forecast of a weak trough in that region, while above-normal temperatures are  
favored in portions of the North Slope, consistent with most temperature  
guidance. For the Panhandle, most of the raw and bias-corrected temperatures  
support below normal temperatures, whereas the various reforecast temperature  
fields favor above normal temperatures. In Hawaii, below-normal temperature  
probabilities are favored across Hawaii underneath weak troughing and negative  
height anomalies. 
 
The subtropical ridge favors below normal precipitation for eastern  Arizona,  
New Mexico, southern Colorado, western and far southern parts of Texas, and  
southern Florida. In contrast, near- to above-normal precipitation  
probabilities are increased over the remainder of the CONUS due to southerly  
return flow associated with mean surface high pressure over the Southeast and  
the mid-level trough expected to linger in the region through much of the  
period, and supported by most of the dynamical precipitation forecast tools.  
Above normal precipitation chances are elevated over most of Alaska in advance  
of a mid-level trough and widespread onshore flow. The exception is over the  
southern Panhandle, where near-normal precipitation is favored under a  
mid-level ridge and positive height anomalies. In Hawaii, anomalously wet  
conditions statewide are likely in advance of a 500-hPa trough. 
 
The official 6-10 day 500-hPa height blend consists of 40% of Today's GFS  
Superensemble Mean centered on Day 8, 30% 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 model solutions and forecast temperature and precipitation  
tools. 
 
 
8-14 DAY OUTLOOK FOR MAY 25 - 31 2024  
 
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. During week-2, positive 500-hPa height  
anomalies persist over the North Pacific and over much of the southern tier of  
the CONUS and Maine. Troughs are predicted along the West Coast and over the  
Great Lakes region. For Alaska, weak anomalous troughing is indicated over the  
Bering Sea and the western coast, with mid-level ridging and positive height  
anomalies dominating the remainder of the state. In Hawaii, a weak trough with  
below-normal 500-hPa heights continue to be forecast northwest of Hawaii. 
 
Above normal temperatures are favored for the south-central and southeastern  
CONUS as well as Maine due to subtropical ridging and above-normal 500-hPa  
heights predicted around the region, and aligns well with the overall synoptic  
pattern. A low-amplitude trough near the West Coast and the Great Lakes tilt  
the odds towards below normal temperatures for the West Coast, parts of the  
Northern and Central Plains, the Upper and Middle Mississippi Valley, and Upper  
Great Lakes region. In Alaska, below normal temperature chances are increased  
over much of the central and southern portions of the state, with above normal  
temperature chances enhanced over the North Slope. In Hawaii, below-normal  
temperatures are likely over the State due to the below-normal 500-hPa heights.  
 
Enhanced chances for above-normal precipitation are favored over northern  
California and the Pacific Northwest in association with a weak trough  
predicted over the West Coast. Above-normal precipitation is also forecast over  
much of the central and eastern CONUS, consistent with the consolidation and  
auto precipitation tools. Below normal precipitation is favored across parts of  
Arizona, New Mexico, and far southwestern Texas, also supported by the  
Consolidation and auto precipitation tools. For Hawaii and Alaska,  
predominantly wet conditions are favored relative to normal with the same  
general synoptic features in place as was the case with the 6-10 day outlook. 
 
The official 8-14 day 500-hPa height blend consists of: 35% of Today's 6z GFS  
Ensemble Mean centered on Day 11, 45% of Today's 0z European Ensemble Mean  
centered on Day 11, and 20% 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, with  
good run-to-run continuity among forecast models, offset by differences between  
models regarding strength and position of various synoptic features. 
 
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 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:  
19660519 - 19990529 - 19920509 - 19890516 - 19990430 
 
 
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:  
19660518 - 19990528 - 19920509 - 19620529 - 19640426 
 
 
6-10 DAY OUTLOOK TABLE 
Outlook for May 23 - 27 2024 
 
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   B    A     WYOMING     B    A      
UTAH        B    A     ARIZONA     B    N     COLORADO    B    N      
NEW MEXICO  A    B     N DAKOTA    B    A     S DAKOTA    B    A      
NEBRASKA    B    A     KANSAS      N    A     OKLAHOMA    A    A      
N TEXAS     A    A     S TEXAS     A    N     W TEXAS     A    B      
MINNESOTA   B    A     IOWA        B    A     MISSOURI    N    A      
ARKANSAS    A    A     LOUISIANA   A    A     WISCONSIN   B    A      
ILLINOIS    N    A     MISSISSIPPI A    A     MICHIGAN    N    A      
INDIANA     N    A     OHIO        N    A     KENTUCKY    A    A      
TENNESSEE   A    A     ALABAMA     A    A     NEW YORK    A    A      
VERMONT     A    A     NEW HAMP    A    A     MAINE       A    A      
MASS        A    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    N     AK N SLOPE  N    A      
AK ALEUTIAN B    A     AK WESTERN  B    A     AK INT BSN  B    A      
AK S INT    B    A     AK SO COAST B    A     AK PNHDL    N    N      
  
                            
 
8-14 DAY OUTLOOK TABLE 
Outlook for May 25 - 31 2024 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  B    A     OREGON      B    A     NRN CALIF   B    A      
SRN CALIF   B    N     IDAHO       N    N     NEVADA      N    N      
W MONTANA   N    N     E MONTANA   N    N     WYOMING     N    N      
UTAH        N    N     ARIZONA     N    N     COLORADO    N    A      
NEW MEXICO  N    N     N DAKOTA    B    A     S DAKOTA    B    A      
NEBRASKA    B    A     KANSAS      N    A     OKLAHOMA    A    A      
N TEXAS     A    A     S TEXAS     A    N     W TEXAS     A    A      
MINNESOTA   B    A     IOWA        B    A     MISSOURI    N    A      
ARKANSAS    A    A     LOUISIANA   A    N     WISCONSIN   B    A      
ILLINOIS    N    A     MISSISSIPPI A    A     MICHIGAN    N    A      
INDIANA     N    A     OHIO        N    A     KENTUCKY    N    A      
TENNESSEE   N    A     ALABAMA     A    A     NEW YORK    N    A      
VERMONT     N    A     NEW HAMP    N    A     MAINE       A    A      
MASS        N    A     CONN        N    A     RHODE IS    N    A      
PENN        N    A     NEW JERSEY  N    A     W VIRGINIA  N    A      
MARYLAND    N    A     DELAWARE    N    A     VIRGINIA    N    A      
N CAROLINA  A    A     S CAROLINA  A    A     GEORGIA     A    A      
FL PNHDL    A    A     FL PENIN    A    A     AK N SLOPE  A    A      
AK ALEUTIAN B    A     AK WESTERN  B    A     AK INT BSN  B    A      
AK S INT    B    A     AK SO COAST B    A     AK PNHDL    N    N      
  
                           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. 
 
$$