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 Fri July 26 2024 
 
6-10 DAY OUTLOOK FOR AUG 01 - 05 2024 
 
There is good agreement on the 500-hPa height forecast across North America  
between the 0Z ensemble mean solutions of the ECMWF, GEFS and Canadian models.  
Model solutions predict cyclonic flow over most of Alaska ahead of a trough  
centered to the west of the state. Negative 500-hPa height anomalies are  
forecast over Mainland Alaska and positive anomalies are predicted over the  
Aleutians. A shortwave trough and negative 500-hPa height anomalies are  
predicted to extend southward into the North Pacific to the west of North  
America. A ridge and associated positive 500-hPa height anomalies cover most of  
the CONUS, with a weakness in positive 500-hPa height anomalies over the  
Southeast. Weak positive 500-hPa height anomalies are predicted over Hawaii by  
the ECMWF ensemble mean, while near average 500-hPa heights are predicted over  
Hawaii by the GEFS.  
 
Below-normal temperatures are likely over most of Alaska, including the eastern  
Aleutians, Mainland Alaska, and Southeast Alaska, under mostly northwesterly  
flow or negative 500-hPa height anomalies. Near-to-below-normal temperatures  
are favored for southern Texas along with weaker probabilities favoring  
above-normal temperatures into parts of the Southeast, consistent with  
short-term bias-corrected temperature forecasts of the GEFS and ECMWF ensemble  
models. Above-normal temperatures are likely across the remainder of the CONUS,  
as positive 500-hPa height anomalies are predicted over the entire CONUS during  
most of the period. Above-normal temperatures are favored for Hawaii, under  
weak positive 500-hPa height anomalies.  
 
Above-normal precipitation is favored across most of Alaska, under enhanced  
onshore flow or cyclonic flow ahead of a trough. Near-to-below-normal  
precipitation is favored for the southern Alaska Panhandle, consistent with  
reforecast-calibrated precipitation forecasts from the GEFS and ECMWF  
ensembles. Below-normal precipitation is slightly favored over a large area of  
the northwestern CONUS and favored for most of the central CONUS, consistent  
with most dynamical model forecasts. Above-normal precipitation is favored over  
much of the eastern CONUS, consistent with most dynamical model precipitation  
tools with enhanced moisture flow from the tropics. Below-normal precipitation  
is favored for Hawaii, as predicted by the Auto precipitation forecast tool and  
consistent with the consolidation. 
 
The official 6-10 day 500-hPa height blend consists of 35% of Today's 0z GFS  
Ensemble Mean centered on Day 8, 45% of Today's 0z European Ensemble Mean  
centered on Day 8, and 20% 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 general agreement among the dynamical model height forecasts and tools and  
day-to-day run consistency, offset by differences in temperature and  
precipitation tools for some areas, such as the west coast of the CONUS and the  
Southeast. 
 
8-14 DAY OUTLOOK FOR AUG 03 - 09 2024  
 
The week-2 manual blend and the ECMWF, GEFS and Canadian ensemble mean  
forecasts predict positive 500-hPa height anomalies over the western Aleutian  
Islands and across most of the CONUS. Negative 500-hPa height anomalies are  
predicted over Mainland and Southeast Alaska, and near-average 500-hPa heights  
are predicted over the southeastern CONUS. Troughs continue to be predicted to  
the west and south of Alaska. Ensemble means from the GEFS, ECMWF and Canadian  
models predict a ridge over the western and central CONUS with troughing and  
relatively weaker positive 500-hPa height anomalies predicted over the eastern  
CONUS.  
 
Above-normal temperatures are predicted across most of the CONUS, under a ridge  
and consistent with most dynamical model temperature tools. Near-normal  
temperatures are favored for parts of South Texas, consistent with the  
automated temperature forecast blend of tools. Below-normal temperatures are  
favored for the eastern Aleutians, most of Mainland Alaska, and Southeast  
Alaska, under predicted negative 500-hPa height anomalies or anomalous  
northwesterly flow in the manual blend and most dynamical model forecasts.  
Near-normal temperatures are favored for parts of the North Slope, consistent  
with the temperature consolidation. Above-normal temperatures are favored for  
Hawaii, under weak positive 500-hPa height anomalies.  
 
Above-normal precipitation continues to be favored for the eastern Aleutians,  
Mainland Alaska, and northern area of Southeast Alaska, under enhanced onshore  
and cyclonic flow. Near-to-below-normal precipitation is favored for the  
southern Alaska Panhandle, under rising positive 500-hPa height anomalies.  
Below -normal precipitation is slightly favored for parts of the Pacific  
Northwest, consistent with most dynamical model tools and rising mid-level  
heights. Above-normal precipitation is slightly favored for southern and  
central California, much of Nevada, Utah, and western Arizona, with a possible  
surge of moisture from development of a tropical system in the Eastern Pacific.  
Below-normal precipitation is favored for most of the central and northern  
Great Plains, as well as the upper Mississippi Valley in week-2, under the  
predicted persistent ridge. Above-normal precipitation is slightly favored over  
the Gulf coast region and the eastern CONUS, consistent with most precipitation  
tools and the consolidation. Near-normal precipitation is favored across  
Hawaii, where precipitation tools are inconsistent. 
 
The official 8-14 day 500-hPa height blend consists of: 35% of Today's 0z 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: About-average, 3 out of 5, due to  
good general agreement among the dynamical model height forecasts, offset by  
differences in temperature and precipitation tools for some areas. 
 
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  
August 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:  
19510706 - 19520706 - 19530706 - 19540706 - 19550706 
 
 
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:  
19510705 - 19520705 - 19530705 - 19540705 - 19550705 
 
 
6-10 DAY OUTLOOK TABLE 
Outlook for Aug 01 - 05 2024 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  A    B     OREGON      A    B     NRN CALIF   A    N      
SRN CALIF   A    A     IDAHO       A    B     NEVADA      A    B      
W MONTANA   A    B     E MONTANA   A    B     WYOMING     A    B      
UTAH        A    N     ARIZONA     A    N     COLORADO    A    B      
NEW MEXICO  A    B     N DAKOTA    A    B     S DAKOTA    A    B      
NEBRASKA    A    B     KANSAS      A    B     OKLAHOMA    A    N      
N TEXAS     A    N     S TEXAS     N    A     W TEXAS     A    N      
MINNESOTA   A    B     IOWA        A    B     MISSOURI    A    N      
ARKANSAS    A    A     LOUISIANA   A    A     WISCONSIN   A    N      
ILLINOIS    A    N     MISSISSIPPI A    A     MICHIGAN    A    N      
INDIANA     A    A     OHIO        A    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    A     AK N SLOPE  B    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    B    N      
  
                            
 
8-14 DAY OUTLOOK TABLE 
Outlook for Aug 03 - 09 2024 
 
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    B     WYOMING     A    N      
UTAH        A    A     ARIZONA     A    A     COLORADO    A    N      
NEW MEXICO  A    N     N DAKOTA    A    B     S DAKOTA    A    B      
NEBRASKA    A    B     KANSAS      A    B     OKLAHOMA    A    N      
N TEXAS     A    A     S TEXAS     A    A     W TEXAS     A    N      
MINNESOTA   A    B     IOWA        A    B     MISSOURI    A    N      
ARKANSAS    A    A     LOUISIANA   A    A     WISCONSIN   A    B      
ILLINOIS    A    N     MISSISSIPPI A    A     MICHIGAN    A    N      
INDIANA     A    N     OHIO        A    A     KENTUCKY    A    A      
TENNESSEE   A    A     ALABAMA     A    A     NEW YORK    A    A      
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    N     W VIRGINIA  A    A      
MARYLAND    A    N     DELAWARE    A    N     VIRGINIA    A    N      
N CAROLINA  A    N     S CAROLINA  A    N     GEORGIA     A    A      
FL PNHDL    A    A     FL PENIN    A    A     AK N SLOPE  B    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    B    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. 
 
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