Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks 
NWS Climate Prediction Center College Park, MD 
300 PM EDT Wed April 08 2020 
 
6-10 DAY OUTLOOK FOR APR 14 - 18 2020 
 
Dynamical model guidance remains in good agreement in predicting an amplified  
mean 500-hPa geopotential height pattern over North America during the 6-10 day  
period. Model solutions depict a mean ridge over the northeastern Pacific, with  
positive 500-hPa height anomalies over much of Alaska and along the West Coast  
of the CONUS. Downstream, an amplified mean trough centered over the upper  
Midwest and Great Lakes favors negative 500-hPa height anomalies for much of  
the CONUS from the Rockies to the East Coast, extending southward to the Rio  
Grande and Lower Mississippi Valleys. A predicted  mean subtropical ridge over  
the Caribbean and Atlantic favors above-normal 500-hPa heights over Florida and  
extreme southern portions of Georgia. 
 
Mean troughing over the western Bering Sea and the amplified mean ridge over  
the northeastern Pacific favor mid-level southwesterly flow and above-normal  
temperatures over much of Alaska. Over the CONUS, above-normal temperatures are  
favored for the West Coast, with positive 500-hPa height anomalies along the  
east side of the mean Pacific ridge. Enhanced probabilities for below-normal  
temperatures are favored for much of the central and eastern CONUS, in  
association with an amplified mean trough. Large probabilities (80 to 90  
percent, or more) of below-normal temperatures across the Great Plains and  
Midwest are supported by good model consistency with the high amplitude pattern  
along with daily negative departures from normal of more than -15°F for several  
locations during the period. Above-normal temperatures are favored for much of  
Florida and extreme southern Georgia, in association with a predicted mean  
subtropical ridge. 
 
Mean mid-level southwesterly flow favors enhanced probabilities for  
above-normal precipitation over much of Alaska. Below-normal precipitation is  
favored over much of the West Coast of the CONUS, in association with the  
eastern extent of the mean Pacific ridge. Below-normal precipitation is also  
favored over the Northern and Southern Plains and Mississippi Valley, as  
surface high pressure is expected to remain dominant throughout the entire  
period. Above-normal precipitation is favored over the eastern Rockies and Four  
Corners region, in association with a short-wave trough moving southward out of  
Canada and potentially aiding lee cyclogenesis over the central High Plains in  
the mid-to-late part of the period. Elevated probabilities for above-normal  
precipitation over the East Coast are associated with the continued deep  
southward expanse of the mean trough, increasing potential for greater moisture  
advection from the Gulf of Mexico. 
 
The official 6-10 day 500-hPa height blend consists of 50% of Today's 6z GFS  
Ensemble Mean centered on Day 8, and 50% of Today's 0z European Ensemble Mean  
centered on Day 8  
  
 
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Above average, 4 out of 5, due to  
good model agreement over most of the CONUS, offset by some uncertainty among  
the forecast tools in the temperature forecast for Alaska. 
 
8-14 DAY OUTLOOK FOR APR 16 - 22 2020  
 
During the 8-14 day period, mean 500-hPa ridging is favored over the  
northeastern Pacific, leading to positive 500-hPa height anomalies over most of  
Alaska, the West Coast, Great Basin, and western Rockies. An amplified trough  
centered over the Great Lakes and Northeast favors negative 500-hPa height  
anomalies over much of the CONUS. Above-normal 500-hPa heights are favored over  
Florida, in association with weak mean ridging in the western Atlantic. 
 
Today's ECMWF ensemble depicts a deamplified ridge over the northeast Pacific,  
compared to yesterday, bringing the mid-level height pattern more in-line with  
the GEFS, which shows a more suppressed ridge along its northeastern extent.  
Also, with a mean trough over the western Bering Sea favoring overall mean  
mid-level southwesterly flow, and warm signals in both the GEFS and ECMWF  
reforecast tools, odds are tilted toward above-normal temperatures for much of  
Alaska, with weakly positive and near-normal probabilities over central and  
northeastern Mainland Alaska, respectively. Above-normal temperatures are  
favored for the West Coast and Great Basin along the eastern extent of the mean  
Pacific ridge. The amplified mean trough over the Great Lakes favors enhanced  
probabilities for below-normal temperatures over most of the CONUS, extending  
as far south as the Rio Grande Valley. Large probabilities (70 percent or more)  
of below-normal temperatures across much of the Midwest and Corn Belt continue  
to be supported by good model consistency in a high amplitude long-wave  
pattern. Above-normal temperatures are favored for the Florida Peninsula in  
association with positive 500-hPa height anomalies. 
 
Above-normal precipitation is favored for Mainland Alaska, in association with  
mean southwesterly flow and an active storm track throughout the 8-14 day  
period. Near- and below-normal precipitation is favored for the Alaska  
Panhandle, the Pacific Northwest, and northern California, along the eastern  
extent of the mean Pacific ridge. Similar to the 6-10 day period, the storm  
track is favored to remain farther south over the CONUS, leading to  
probabilities for below-normal precipitation across the Northern Plains and  
Upper Mississippi Valley. Weak probabilities for above-normal precipitation are  
indicated across the Rockies, Great Basin, and central High Plains, in  
association with a potential low-pressure system propagating southeastward out  
of Canada along the mean trough midway through the period. The mean trough over  
the eastern CONUS increases odds for increased moisture advection from the Gulf  
of Mexico and above-normal precipitation along the East Coast. 
 
The official 8-14 day 500-hPa height blend consists of: 50% of Today's 6z GFS  
Ensemble Mean centered on Day 11, and 50% 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 good  
agreement among guidance in the overall amplified 500-hPa geopotential height  
pattern, offset by some uncertainty in the eastward propagation of the overall  
mid-level pattern between the GEFS and ECMWF ensemble. 
 
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  
April 16. 
 
 
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:  
19610421 - 19590416 - 20020419 - 20010403 - 19790416 
 
 
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:  
19650331 - 19610421 - 20010402 - 20020420 - 19770328 
 
 
6-10 DAY OUTLOOK TABLE 
Outlook for Apr 14 - 18 2020 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  N    B     OREGON      A    B     NRN CALIF   A    B      
SRN CALIF   A    N     IDAHO       B    B     NEVADA      B    N      
W MONTANA   B    N     E MONTANA   B    B     WYOMING     B    A      
UTAH        B    A     ARIZONA     B    N     COLORADO    B    A      
NEW MEXICO  B    N     N DAKOTA    B    B     S DAKOTA    B    B      
NEBRASKA    B    B     KANSAS      B    A     OKLAHOMA    B    B      
N TEXAS     B    B     S TEXAS     B    B     W TEXAS     B    N      
MINNESOTA   B    B     IOWA        B    B     MISSOURI    B    B      
ARKANSAS    B    B     LOUISIANA   B    B     WISCONSIN   B    B      
ILLINOIS    B    B     MISSISSIPPI B    B     MICHIGAN    B    N      
INDIANA     B    N     OHIO        B    A     KENTUCKY    B    A      
TENNESSEE   B    A     ALABAMA     B    A     NEW YORK    B    A      
VERMONT     B    A     NEW HAMP    B    A     MAINE       B    A      
MASS        B    A     CONN        B    A     RHODE IS    B    A      
PENN        B    A     NEW JERSEY  B    A     W VIRGINIA  B    A      
MARYLAND    B    A     DELAWARE    B    A     VIRGINIA    B    A      
N CAROLINA  B    A     S CAROLINA  B    A     GEORGIA     B    A      
FL PNHDL    A    A     FL PENIN    A    A     AK N SLOPE  A    A      
AK ALEUTIAN A    A     AK WESTERN  A    A     AK INT BSN  A    A      
AK S INT    A    A     AK SO COAST A    A     AK PNHDL    A    B      
  
                            
 
8-14 DAY OUTLOOK TABLE 
Outlook for Apr 16 - 22 2020 
 
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN    
WASHINGTON  A    B     OREGON      A    B     NRN CALIF   A    B      
SRN CALIF   A    N     IDAHO       N    N     NEVADA      A    N      
W MONTANA   B    N     E MONTANA   B    N     WYOMING     B    N      
UTAH        N    A     ARIZONA     N    N     COLORADO    B    A      
NEW MEXICO  B    A     N DAKOTA    B    B     S DAKOTA    B    B      
NEBRASKA    B    B     KANSAS      B    N     OKLAHOMA    B    N      
N TEXAS     B    N     S TEXAS     B    A     W TEXAS     B    N      
MINNESOTA   B    B     IOWA        B    B     MISSOURI    B    N      
ARKANSAS    B    N     LOUISIANA   B    A     WISCONSIN   B    B      
ILLINOIS    B    N     MISSISSIPPI B    A     MICHIGAN    B    N      
INDIANA     B    N     OHIO        B    A     KENTUCKY    B    A      
TENNESSEE   B    A     ALABAMA     B    A     NEW YORK    B    A      
VERMONT     B    A     NEW HAMP    B    A     MAINE       B    A      
MASS        B    A     CONN        B    A     RHODE IS    B    A      
PENN        B    A     NEW JERSEY  B    A     W VIRGINIA  B    A      
MARYLAND    B    A     DELAWARE    B    A     VIRGINIA    B    A      
N CAROLINA  B    A     S CAROLINA  B    A     GEORGIA     B    A      
FL PNHDL    N    A     FL PENIN    A    A     AK N SLOPE  N    A      
AK ALEUTIAN A    N     AK WESTERN  A    A     AK INT BSN  A    A      
AK S INT    A    A     AK SO COAST A    A     AK PNHDL    A    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. 
 
$$