Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks 
NWS Climate Prediction Center College Park, MD 
300 PM EST Tue December 05 2023 
 
6-10 DAY OUTLOOK FOR DEC 11 - 15 2023 
 
Today’s ensemble mean model solutions are in fairly good agreement on the  
500-hPa mean flow pattern across North America and adjacent oceanic areas  
during the 6-10 day forecast period. Anomaly correlation scores for the past 60  
days do not significantly favor one model over another, hence the manual height  
blend is composed of nearly equal weights of the 00z runs of the GFS, ECMWF,  
and Canadian ensemble means. The manual height blend depicts mid-level ridging  
and above normal 500-hPa heights over far eastern Siberia, and mid-level  
troughing and modestly below normal 500-hPa heights over most of Alaska. A  
broad ridge and above normal 500-hPa heights are predicted near the west coast  
of North America. This ridge is forecast to be significantly more amplified  
than it was yesterday on the manual height blend. Downstream, over much of the  
Central and Eastern contiguous U.S. (CONUS), the manual height blend depicts an  
anomalous mid-level trough over the Great Lakes region, Ohio Valley, and  
Northeast. 
 
The 6-10 day temperature outlook favors above normal temperatures over  
California, southwestern portions of Oregon and Utah, and most of Nevada and  
Arizona. Probabilities favoring above normal temperatures exceed 60% over parts  
of coastal southern California. Odds also favor above normal temperatures over  
the vicinity of the Dakotas, the Northeast, and southern Florida. All of these  
favored areas of relative warmth are supported by the consolidation and  
automated temperature tools. Odds favor below normal temperatures from central  
New Mexico eastward across the southern Plains, Lower Mississippi Valley, and  
parts of the Southeast. This is also supported by the consolidation and  
automated temperature tools. Near normal temperatures are favored for remaining  
areas of the CONUS, which encompass a large fraction of the Lower 48 states.  
This includes portions of the northern Intermountain region and central  
Rockies, where pre-existing snow cover favors radiational cooling and the  
overall reduction of temperatures. Below normal temperature chances are  
increased over western Alaska, due to a mid-level trough and widespread  
northerly flow predicted over the area. With the more amplified mid-level ridge  
now predicted over the west coast of North America in today’s model runs, there  
is a tilt in the odds towards above normal temperatures across southeastern  
Alaska. For Hawaii, relatively warm sea-surface temperatures and a very weak  
mid-level height anomaly pattern favor above normal temperatures for the  
islands, supported by the ERF-CON temperature tool. 
 
The 6-10 day precipitation outlook favors below normal precipitation for most  
of the Lower 48 states, associated with widespread northwesterly and westerly  
mid-level flow. This is consistent with reforecast-calibrated precipitation  
from the three ensemble means. Relatively small-scale areas of favored above  
normal precipitation are depicted over Maine, Florida, and much of Texas. For  
most of Alaska, above normal precipitation chances are enhanced, due to the  
proximity of a mid-level trough over the western part of the state, and an  
amplifying ridge over the southeastern part of the state. This overall pattern  
is conducive to widespread onshore flow across Alaska.  Well to the south, near  
normal precipitation is favored for most of the Hawaiian islands, with the  
exception of the southern portion of the Big Island where there is a slight  
tilt towards below normal precipitation. This is consistent with the  
auto-precipitation and ERF-CON precipitation tools. 
 
The official 6-10 day 500-hPa height blend consists of 33% of Today's 0z GFS  
Ensemble Mean centered on Day 8, 34% of Today's 0z European Ensemble Mean  
centered on Day 8, and 33% of Today's 0z Canadian Ensemble Mean centered on Day  
8  
  
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Above average, 4 on a scale of  
1-5, based on fairly good agreement among the various 500-hPa height models,  
and the surface temperature and precipitation tools. 
 
8-14 DAY OUTLOOK FOR DEC 13 - 19 2023  
 
Today’s 00z ensemble mean solutions from the GFS, ECMWF, and Canadian dynamical  
models are in good agreement on the predicted large-scale 500-hPa height  
pattern across the forecast domain. These solutions depict a broad anomalous  
ridge over most of the CONUS, and a smaller-scale anomalous ridge in the  
general vicinity of 35N-40N/160W-165W (north-northwest of the Hawaiian  
islands). Negative 500-hPa height anomalies are indicated over Alaska, the Gulf  
of Alaska, and the northern half of Canada. Southern stream energy is predicted  
to move into California and the Southwest during week-2, increasing the  
likelihood for cloud cover and precipitation. 
 
The 8-14 day temperature outlook favors above normal temperatures across  
approximately the northern half to two-thirds of the CONUS, associated with  
mid-level anomalous ridging. This is generally consistent with the  
reforecast-calibrated temperature tools from the various ensemble means.  
However, there is hardly any statistical support for favored above normal  
temperatures across the far southern portions of the West, which is why the  
outlook for that region was left as favoring near normal. Above normal  
temperature chances are elevated over most of Florida. In Southeast Alaska,  
above normal temperatures are favored, in proximity to a mid-level ridge. For  
approximately the western half of Alaska, odds tilt towards below normal  
temperatures due to the proximity of a mid-level trough and below normal  
500-hPa heights. As was the case yesterday, the mid-level trough predicted over  
much of Alaska is forecast to be deeper during week-2 than during the earlier  
6-10 day period. Above normal temperatures are favored across the Hawaiian  
islands, consistent with ERF-CON and automated temperature guidance. 
 
The 8-14 day precipitation outlook favors above normal precipitation over  
California and adjacent parts of Nevada. Predicted surface high pressure over  
the Southeast leads to moist, easterly flow and increased chances of above  
normal precipitation for Florida and neighboring parts of the Southern Atlantic  
coast. Return flow around this surface anticyclone tilts the odds towards above  
normal precipitation for much of the southern and central Plains, associated  
with an expected increase in low-level Gulf moisture. Below normal  
precipitation is favored from the northern Intermountain region and northern  
half of the Rockies eastward across the northern Plains, Upper Mississippi  
Valley, Great Lakes region, Ohio and Tennessee Valleys, most of the  
Appalachians, and the Atlantic coastal plain from Maine to the Delmarva  
Peninsula. This is supported by the auto-precipitation and consolidated  
precipitation tools. This is also consistent with predicted widespread  
anomalous mid-level ridging and positive 500-hPa height anomalies. The week-2  
precipitation outlook for Alaska favors near normal precipitation chances  
across far western portions of Alaska, and above normal precipitation chances  
elsewhere, associated with a significant mid-level trough, below normal 500-hPa  
heights, and cyclonic curvature. Near normal precipitation chances are favored  
across most of Hawaii, based on a compromise between the ERF-CON precipitation  
guidance and the auto-precipitation tool. 
 
The official 8-14 day 500-hPa height blend consists of: 33% of Today's 0z GFS  
Ensemble Mean centered on Day 11, 34% of Today's 0z European Ensemble Mean  
centered on Day 11, and 33% of Today's 0z Canadian Ensemble Mean centered on  
Day 11  
 
 
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Above average, 4 on a scale of  
1-5, based on fairly good agreement between the ensemble mean 500-hPa height  
forecasts, offset by some disagreements in the surface tools. 
 
FORECASTER: Anthony A 
 
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  
December 21. 
 
 
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:  
20031214 - 19601118 - 19811202 - 19881128 - 19591121 
 
 
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:  
19531125 - 19681119 - 20031215 - 19811202 - 19591120 
 
 
6-10 DAY OUTLOOK TABLE 
Outlook for Dec 11 - 15 2023 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  N    B     OREGON      N    B     NRN CALIF   A    B      
SRN CALIF   A    B     IDAHO       N    B     NEVADA      A    B      
W MONTANA   N    B     E MONTANA   N    B     WYOMING     N    B      
UTAH        N    B     ARIZONA     A    B     COLORADO    N    B      
NEW MEXICO  N    B     N DAKOTA    A    B     S DAKOTA    A    B      
NEBRASKA    N    B     KANSAS      N    N     OKLAHOMA    N    N      
N TEXAS     B    B     S TEXAS     B    A     W TEXAS     B    N      
MINNESOTA   N    B     IOWA        N    B     MISSOURI    N    B      
ARKANSAS    N    B     LOUISIANA   B    B     WISCONSIN   N    B      
ILLINOIS    N    B     MISSISSIPPI B    B     MICHIGAN    N    B      
INDIANA     N    B     OHIO        N    B     KENTUCKY    N    B      
TENNESSEE   N    B     ALABAMA     B    B     NEW YORK    A    N      
VERMONT     A    N     NEW HAMP    A    N     MAINE       A    A      
MASS        A    N     CONN        A    N     RHODE IS    A    N      
PENN        N    B     NEW JERSEY  A    N     W VIRGINIA  N    B      
MARYLAND    N    N     DELAWARE    N    N     VIRGINIA    N    B      
N CAROLINA  N    N     S CAROLINA  N    B     GEORGIA     N    B      
FL PNHDL    B    N     FL PENIN    A    A     AK N SLOPE  N    A      
AK ALEUTIAN B    N     AK WESTERN  B    A     AK INT BSN  N    A      
AK S INT    N    A     AK SO COAST A    A     AK PNHDL    A    A      
  
                            
 
8-14 DAY OUTLOOK TABLE 
Outlook for Dec 13 - 19 2023 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  A    N     OREGON      A    N     NRN CALIF   A    A      
SRN CALIF   N    A     IDAHO       A    B     NEVADA      A    N      
W MONTANA   A    B     E MONTANA   A    B     WYOMING     A    B      
UTAH        A    N     ARIZONA     N    N     COLORADO    A    N      
NEW MEXICO  N    A     N DAKOTA    A    B     S DAKOTA    A    B      
NEBRASKA    A    N     KANSAS      A    A     OKLAHOMA    A    A      
N TEXAS     N    A     S TEXAS     N    A     W TEXAS     N    A      
MINNESOTA   A    B     IOWA        A    N     MISSOURI    A    A      
ARKANSAS    A    N     LOUISIANA   N    N     WISCONSIN   A    B      
ILLINOIS    A    N     MISSISSIPPI N    N     MICHIGAN    A    B      
INDIANA     A    B     OHIO        A    B     KENTUCKY    A    B      
TENNESSEE   N    B     ALABAMA     N    N     NEW YORK    A    B      
VERMONT     A    B     NEW HAMP    A    B     MAINE       A    B      
MASS        A    B     CONN        A    B     RHODE IS    A    B      
PENN        A    B     NEW JERSEY  A    B     W VIRGINIA  A    B      
MARYLAND    A    B     DELAWARE    A    B     VIRGINIA    N    B      
N CAROLINA  N    N     S CAROLINA  N    A     GEORGIA     N    A      
FL PNHDL    N    A     FL PENIN    A    A     AK N SLOPE  B    A      
AK ALEUTIAN B    N     AK WESTERN  B    N     AK INT BSN  N    A      
AK S INT    N    A     AK SO COAST B    A     AK PNHDL    A    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. 
 
$$