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6-10 Day outlooks are issued daily between 3pm & 4pm Eastern Time. All forecasts issued on weekends are completely automated while all weekday outlooks are modified by the forecaster.
 
Please refer to the U.S. Prognostic Discussion for an explanation of terms and symbols used on these maps.


 
 
HOME> Outlook Maps> Prognostic Map Discussion
 
Prognostic Discussions
Valid: Oct 29 - Nov 02, 2020 (6-10 Day Outlook)
Valid: Oct 31 - Nov 06, 2020 (8-14 Day Outlook)
Issued: Oct 23, 2020

Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks 
NWS Climate Prediction Center College Park, MD 
300 PM EDT Fri October 23 2020 
 
6-10 DAY OUTLOOK FOR OCT 29 - NOV 02, 2020 
 
Today's dynamical model forecasts agree on a moderately amplified 500-hPa  
geopotential height pattern over North America during the 6-10 day period.  
Today's model solutions have a more amplified mid-level trough over Alaska and  
into western Canada, compared to yesterday's solutions. Troughing is also  
favored over the eastern CONUS. There is some uncertainty regarding the  
strength of the trough over Alaska, and the speed at which the trough over the  
eastern CONUS exits off the Northeast coast. However, there is decent agreement  
with respect to the locations of the 500-hPa features over North America.  
Today's manual height blend indicates positive 500-hPa height anomalies across  
extreme southwestern Alaska, with negative height anomalies elsewhere in the  
state, associated with a predicted amplified mid-level trough. Positive 500-hPa  
height anomalies are prevalent across the western two-thirds of the CONUS  
underneath an deamplified ridge, with respect to yesterday's forecast. Positive  
500-hPa height anomalies are also favored across parts of the Southeast and  
Gulf Coast, associated with broad subtropical ridging over the Atlantic Ocean.  
Below normal 500-hPa heights are favored over the Great Lakes and Northeast,  
associated with a predicted mean trough that is expected to exit early in the  
period. 
 
Enhanced probabilities for above-normal temperatures are favored across extreme  
western and northwestern Mainland Alaska and the western Aleutians, underneath  
positive 500-hPa height anomalies. Below-normal temperatures are favored in  
southeastern areas of the Mainland, extending into the Panhandle, due to an  
amplified mid-level mean trough. Probabilities of above-normal temperatures are  
indicated along the West Coast, underneath above-normal 500-hPa heights,  
although probabilities have decreased since yesterday as the amplified trough  
over Alaska looks to be weakening the mean ridge over the western CONUS. In the  
Southeast, influence from an Atlantic subtropical ridge favors enhanced  
probabilities of above-normal temperatures. Below-normal temperatures are  
favored early in the period for parts of the Great Plains, Midwest, and  
Northeast, as a trough of low pressure is predicted to exit early in the  
forecast period. 
 
The storm track is predicted to remain just south of Alaska, favoring  
above-normal precipitation in the Aleutians, southeastern portions of the  
Alaska Mainland, and the Panhandle. Surface high pressure and predominantly  
easterly surface flow favor below-normal precipitation in much of the central  
Alaska Mainland. Odds are tilted toward above-normal precipitation in northern  
Mainland Alaska, in association with short-wave activity and a drier  
climatology compared to southern parts of the state. Below-normal precipitation  
is favored across much of the central CONUS, extending into the Rockies,  
underneath positive 500-hPa height anomalies. Above-normal precipitation is  
favored for the Pacific Northwest due to the amplified mean trough and  
associated onshore flow. Above-normal precipitation in the eastern CONUS is  
associated with a trough of low pressure exiting the East Coast early in the  
period. 
 
The official 6-10 day 500-hPa height blend consists of 40% of Today's 6z GFS  
Ensemble Mean centered on Day 8, and 60% of Today's 0z European Ensemble Mean  
centered on Day 8  
  
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Average, 3 out of 5, due to good  
model agreement in the overall location of the 500-hPa height features across  
North America, offset by some uncertainty in the amplitude and propagation of  
the pattern, particularly the trough features. 
 
8-14 DAY OUTLOOK FOR OCT 31 - NOV 06, 2020  
 
Today's model solutions show stark contrasts between some of the major 500-hPa  
features upstream and downstream of the forecast domain. The GEFS (ECMWF  
ensemble) shows an weak (amplified) ridge upstream of the amplified trough over  
Alaska and western Canada. In addition, the strong negative 500-hPa height  
anomalies over central and eastern Canada in yesterday's forecast have  
decreased significantly (i.e. less negative) in the ECMWF ensemble. This has a  
large impact on the predicted 500-hPa height fields, particularly over Canada,  
which have led to differences in the surface fields over portions of the  
northern CONUS. Today's manual 500-hPa height blend consists of positive  
500-hPa height anomalies across the far western Aleutians, with below-normal  
500-hPa heights elsewhere over Alaska. The CONUS is dominated by above-normal  
500-hPa heights underneath mean ridging, except for parts of the Northeast,  
where near-normal heights are favored, associated with a trough forecast to  
exit the East Coast early in the Week-2 period. 
 
Above-normal temperature probabilities are increased over extreme western  
portions of the Alaska Mainland and the western Aleutians, underneath weak  
mid-level ridging over the Bering Sea. Elevated probabilities of below-normal  
temperatures are indicated in southeastern Mainland Alaska, extending into the  
Panhandle, associated with increased troughing and below-normal 500-hPa  
heights. Above-normal temperatures are favored for the western half of the  
CONUS, associated with a broad mean ridge. Probabilities of below-normal  
temperatures remain today for the Northeast, as a trough over the eastern CONUS  
is predicted to exit the East Coast early in the Week-2 period. The southward  
extent of the trailing frontal boundary associated with the departing trough is  
forecast to be limited, tilting odds toward above-normal temperatures in the  
southeastern CONUS. 
 
With mean surface low pressure predicted in the Gulf of Alaska, onshore flow to  
the east of the low favors above-normal precipitation in southeastern Mainland  
Alaska and the Panhandle. Below-normal precipitation is favored on the backside  
of the mean surface low in central and southwestern portions of the Alaska  
Mainland, extending into the Aleutians. Weak probabilities of above-normal  
precipitation along the North Slope in Alaska are associated with potential  
short-wave activity propagating along the mean long-wave pattern early in the  
Week-2 period. With an amplified trough over Alaska and western Canada in  
today's model solutions, increased odds of above-normal precipitation are  
favored in the Pacific Northwest. Weak odds of above-normal precipitation in  
the Florida Peninsula are associated with a lingering frontal boundary,  
associated with an exiting trough early in the Week-2 period. Mean ridging  
favors increased chances for below-normal precipitation over most of the  
remainder of the CONUS. However, there is some disagreement in the model  
precipitation fields, particularly in the Northern Tier states, due to the  
aforementioned differences in the 500-hPa height features over central and  
eastern Canada. 
 
The official 8-14 day 500-hPa height blend consists of: 35% of Today's 6z GFS  
Ensemble Mean centered on Day 11, and 65% of Today's 0z European Ensemble Mean  
centered on Day 11  
 
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Average, 3 out of 5, due to decent  
agreement in model solutions in the overall pattern over the U.S., offset by  
disagreement in some of the major features along the peripheries of the  
forecast domain. 
 
FORECASTER: Adam Hartman 
 
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 1981-2010 base period means for  
temperature...precipitation...and 500-hpa heights as reference in the climate  
outlooks. 
 
The next set of long-lead monthly and seasonal outlooks will be released on  
November 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:  
20031030 - 19861106 - 19841025 - 20031104 - 19911019 
 
 
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:  
20031030 - 19841026 - 19861105 - 19591002 - 19911023 
 
 
6-10 DAY OUTLOOK TABLE 
Outlook for Oct 29 - Nov 02, 2020 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  N    A     OREGON      A    A     NRN CALIF   A    N      
SRN CALIF   A    N     IDAHO       N    B     NEVADA      A    B      
W MONTANA   N    B     E MONTANA   B    B     WYOMING     N    B      
UTAH        A    B     ARIZONA     N    B     COLORADO    N    B      
NEW MEXICO  N    B     N DAKOTA    B    N     S DAKOTA    B    B      
NEBRASKA    N    B     KANSAS      N    B     OKLAHOMA    B    B      
N TEXAS     B    B     S TEXAS     N    B     W TEXAS     N    B      
MINNESOTA   B    N     IOWA        B    B     MISSOURI    B    B      
ARKANSAS    N    B     LOUISIANA   A    B     WISCONSIN   B    B      
ILLINOIS    B    B     MISSISSIPPI A    A     MICHIGAN    B    B      
INDIANA     B    B     OHIO        B    A     KENTUCKY    N    A      
TENNESSEE   A    A     ALABAMA     A    A     NEW YORK    B    A      
VERMONT     B    N     NEW HAMP    B    A     MAINE       B    N      
MASS        B    A     CONN        B    A     RHODE IS    B    A      
PENN        B    A     NEW JERSEY  B    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  N    A      
AK ALEUTIAN A    A     AK WESTERN  N    B     AK INT BSN  B    B      
AK S INT    B    B     AK SO COAST B    A     AK PNHDL    B    A      
  
                            
 
8-14 DAY OUTLOOK TABLE 
Outlook for Oct 31 - Nov 06, 2020 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  A    A     OREGON      A    N     NRN CALIF   A    B      
SRN CALIF   A    N     IDAHO       A    B     NEVADA      A    B      
W MONTANA   A    B     E MONTANA   A    B     WYOMING     A    B      
UTAH        A    B     ARIZONA     A    B     COLORADO    A    B      
NEW MEXICO  A    B     N DAKOTA    A    B     S DAKOTA    A    B      
NEBRASKA    A    B     KANSAS      A    B     OKLAHOMA    A    B      
N TEXAS     N    B     S TEXAS     N    B     W TEXAS     A    B      
MINNESOTA   N    B     IOWA        N    B     MISSOURI    N    B      
ARKANSAS    N    B     LOUISIANA   N    B     WISCONSIN   N    B      
ILLINOIS    N    B     MISSISSIPPI N    B     MICHIGAN    N    B      
INDIANA     N    B     OHIO        N    B     KENTUCKY    N    B      
TENNESSEE   N    B     ALABAMA     A    B     NEW YORK    B    B      
VERMONT     B    N     NEW HAMP    B    N     MAINE       B    N      
MASS        B    N     CONN        B    N     RHODE IS    B    N      
PENN        B    B     NEW JERSEY  N    B     W VIRGINIA  N    B      
MARYLAND    N    B     DELAWARE    N    B     VIRGINIA    N    B      
N CAROLINA  N    B     S CAROLINA  A    B     GEORGIA     A    B      
FL PNHDL    A    B     FL PENIN    A    A     AK N SLOPE  N    N      
AK ALEUTIAN A    N     AK WESTERN  N    B     AK INT BSN  B    B      
AK S INT    B    B     AK SO COAST B    N     AK PNHDL    B    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. 
 
$$ 
 

                   
 
Related Topics:
Prognostic Discussion, Surface Forecasts, 500mb Heights and Anomalies, Time Series of Surface Forecast Skill, Model Guidance Used Our Mission, Who We Are, CPC Information, CPC Web Team
 

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