Preview of NWS' New Version of Forecast
This preview is not operational and should not be used for support decisions.

Prognostic Meteorological Discussion (PMD)

Issued by National Weather Service (NWS)

                            
000
FXUS06 KWBC 231917
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Fri August 23 2019

6-10 DAY OUTLOOK FOR AUG 29 - SEP 02, 2019

Today's GFS, ECMWF, and Canadian ensemble means are in reasonably good 
agreement with their predictions of the 500-hPa flow pattern throughout most of 
the forecast domain during the 6-10 day period. The manual 500-hPa height blend 
is based on the ensemble means of the three models noted earlier, and features 
a mid-level trough over the Bering Sea and Aleutians, a closed trough northeast 
of Alaska, and a trough centered over the Central Great Lakes region and Ohio 
River Valley. Mid-level ridges are predicted near the West Coast and the 
Canadian Maritimes.

There are enhanced probabilities of above normal temperatures across most areas 
west of the Continental Divide, extending eastward across southern Texas. 
Upper-tercile temperatures are also favored near the Atlantic coast, and 
southern and western portions of Alaska. Maximum probabilities for 
upper-tercile temperatures top 80% in and near the Willamette Valley in western 
Oregon. These favored areas of warmer-than-normal temperatures are due to 
mid-level ridging, near to above-normal 500-hPa heights, and (in the case of 
Alaska) coastal sea surface temperatures. In contrast, lower-tercile 
temperatures are favored across most areas of the contiguous U.S. between the 
Rockies and the Appalachians, and over northeastern Alaska. Maximum chances for 
colder-than-normal temperatures exceed 70% over the north-central CONUS. These 
favored areas of anomalous cold are generally associated with mid-level troughs 
and near to below normal 500-hPa heights. The official temperature outlook is 
also based on the automated temperature forecast, the consolidated temperature 
forecast, and GEFS and ECMWF calibrated Reforecast temperatures.

There are elevated odds of above normal precipitation over the Aleutians, the 
Alaska Peninsula, and nearby parts of the Mainland, ahead of and accompanying a 
large mid-level trough. Above normal precipitation is also favored from 
southern portions of California east-northeastward across the southern 
Intermountain region, the southern Rockies, most of the Central and Southern 
Great Plains region, and the south-central Mississippi Valley. This is 
associated with monsoon activity in the Southwest, and frontal activity/upslope 
flow east of the Divide. A third area of favored above normal precipitation is 
depicted across the East Coast states, in advance of a mid-level trough and 
associated with frontal activity. In contrast, lower-tercile precipitation is 
favored over most of central and northern Alaska, the Alaska Panhandle, and 
from the northwestern CONUS to the Central Great Lakes region, in areas of 
northerly anomalous flow and/or ridging and above normal 500-hPa heights. The 
official precipitation outlook is also based on the automated precipitation 
forecast, the consolidated temperature forecast, and GEFS and ECMWF calibrated 
Reforecast precipitation.

The official 6-10 day 500-hPa height blend consists of 25% of Today's 0z GFS 
Ensemble Mean centered on Day 8, 25% of Today's 6z GFS Ensemble Mean centered 
on Day 8, 30% 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 
relatively good agreement between models on the predicted 500-hPa height 
pattern, and among the temperature and precipitation forecast tools.

8-14 DAY OUTLOOK FOR AUG 31 - SEP 06, 2019 

The predicted 500-hPa circulation pattern for Week-2 is expected to be fairly 
similar to the pattern predicted for the 6-10 day period, though with weakening 
of the primary longwave features. The Week-2 surface temperature pattern is 
very similar to the 6-10 day temperature pattern, though with diminished 
anomalies. The closed trough northeast of Alaska is forecast to move farther 
away from the 49th state. The official temperature outlook is based on the 
automated and consolidated temperature forecasts, and GEFS and ECMWF calibrated 
Reforecast temperatures. For the Week-2 precipitation outlook, the eastward 
shifting trough over the Bering Sea is predicted to spread considerable 
precipitation over much of southern and central Alaska, tilting the odds 
towards above normal precipitation there (the exception is the southern 
Panhandle region, where below normal precipitation is favored). Odds favor 
above normal precipitation from southern California and Nevada eastward across 
the Southwest to the Southern Rockies, based on continued monsoonal activity. 
The favored area of above normal precipitation then curves northward to include 
portions of the southern and central High Plains, and the Northern Plains as 
far east as Minnesota. Ahead of the mid-level trough predicted over the Great 
Lakes/Ohio Valley, above normal precipitation is favored east of a line that 
stretches from near the Mississippi Delta region to southern New England, and 
is associated with frontal activity. Today's deterministic GFS (initialized at 
12z) backed off on the possible formation of a tropical cyclone over the 
eastern Gulf of Mexico during the upcoming Labor Day weekend, but the model 
still predicts a westward moving inverted trough accompanied by some 
precipitation across the Gulf. There are increased odds of below normal 
precipitation from the central and south-central Plains northeastward to the 
Lower Great Lakes region, parts of the northwestern CONUS, and (as noted above) 
the southern Alaska Panhandle region. The official precipitation outlook is 
also based on the automated and consolidated precipitation forecasts and the 
GEFS/ECMWF calibrated Reforecast precipitation.

The official 8-14 day 500-hPa height blend consists of: 25% of Today's 0z GFS 
Ensemble Mean centered on Day 11, 25% of Today's 6z GFS Ensemble Mean centered 
on Day 11, 30% 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: Near average, 3 out of 5, due to 
generally good agreement between models on the predicted 500-hPa height 
pattern, but offset somewhat by differences among the temperature and 
precipitation forecast 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 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 
September 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: 
19660810 - 19800904 - 20030803 - 19680827 - 20020809


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: 
19660811 - 19800904 - 20020808 - 19910807 - 19680826


6-10 DAY OUTLOOK TABLE
Outlook for Aug 29 - Sep 02, 2019

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN   
WASHINGTON  A    B     OREGON      A    N     NRN CALIF   A    N     
SRN CALIF   A    A     IDAHO       A    B     NEVADA      A    N     
W MONTANA   N    B     E MONTANA   B    B     WYOMING     B    N     
UTAH        A    N     ARIZONA     A    A     COLORADO    B    A     
NEW MEXICO  A    A     N DAKOTA    B    B     S DAKOTA    B    B     
NEBRASKA    B    A     KANSAS      B    A     OKLAHOMA    B    A     
N TEXAS     B    A     S TEXAS     A    N     W TEXAS     A    A     
MINNESOTA   B    B     IOWA        B    B     MISSOURI    B    A     
ARKANSAS    B    A     LOUISIANA   B    N     WISCONSIN   B    B     
ILLINOIS    B    N     MISSISSIPPI B    N     MICHIGAN    B    B     
INDIANA     B    N     OHIO        B    N     KENTUCKY    B    N     
TENNESSEE   B    N     ALABAMA     B    N     NEW YORK    N    A     
VERMONT     A    A     NEW HAMP    A    A     MAINE       A    A     
MASS        A    A     CONN        A    A     RHODE IS    A    A     
PENN        N    A     NEW JERSEY  A    A     W VIRGINIA  B    N     
MARYLAND    N    A     DELAWARE    A    A     VIRGINIA    N    A     
N CAROLINA  A    A     S CAROLINA  N    A     GEORGIA     N    A     
FL PNHDL    A    A     FL PENIN    A    A     AK N SLOPE  N    B     
AK ALEUTIAN A    A     AK WESTERN  A    N     AK INT BSN  N    B     
AK S INT    A    N     AK SO COAST A    A     AK PNHDL    A    B     
 
                           

8-14 DAY OUTLOOK TABLE
Outlook for Aug 31 - Sep 06, 2019

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    N     NEVADA      A    A     
W MONTANA   A    N     E MONTANA   N    A     WYOMING     A    A     
UTAH        A    N     ARIZONA     A    A     COLORADO    N    A     
NEW MEXICO  N    A     N DAKOTA    B    A     S DAKOTA    B    A     
NEBRASKA    B    N     KANSAS      B    B     OKLAHOMA    B    B     
N TEXAS     B    N     S TEXAS     N    N     W TEXAS     N    N     
MINNESOTA   B    N     IOWA        B    B     MISSOURI    B    B     
ARKANSAS    B    B     LOUISIANA   B    N     WISCONSIN   B    N     
ILLINOIS    B    B     MISSISSIPPI B    A     MICHIGAN    B    B     
INDIANA     B    B     OHIO        B    B     KENTUCKY    B    B     
TENNESSEE   B    N     ALABAMA     B    A     NEW YORK    A    N     
VERMONT     A    N     NEW HAMP    A    N     MAINE       A    N     
MASS        A    A     CONN        A    A     RHODE IS    A    A     
PENN        N    N     NEW JERSEY  A    A     W VIRGINIA  B    N     
MARYLAND    A    A     DELAWARE    A    A     VIRGINIA    N    A     
N CAROLINA  A    A     S CAROLINA  N    A     GEORGIA     N    A     
FL PNHDL    N    A     FL PENIN    A    A     AK N SLOPE  A    N     
AK ALEUTIAN A    A     AK WESTERN  A    A     AK INT BSN  N    A     
AK S INT    A    A     AK SO COAST A    A     AK PNHDL    A    B     
 
                           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.

$$