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Prognostic Meteorological Discussion (PMD)

Issued by National Weather Service (NWS)

                            
000
FXUS06 KWBC 211902
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Thu March 21 2019

6-10 DAY OUTLOOK FOR MAR 27 - 31 2019

Today's model solutions depict a highly amplified 500-hPa pattern across 
northern North America, punctuated by strong ridging over Alaska and a 
downstream trough across east-central Canada. Farther to the south, enhanced 
Pacific flow is forecast across much of the western CONUS. Weak ridging is 
predicted downstream across parts of the Mississippi Valley Region and a trough 
is forecast farther to the east, well off the southeastern coast of the CONUS. 
Today's official 500-hPa height blend features well above normal heights across 
most of Alaska. Below normal heights are favored over much of the west coast of 
the CONUS while slightly above normal heights are indicated from the Southern 
Plains to the Northeast. Near normal heights are favored across the remainder 
of the forecast domain.

Strong ridging favors above normal temperatures across Alaska with 
probabilities exceeding 80 percent for parts of the western mainland. 
Probabilities of above normal temperatures are slightly elevated for parts of 
the Pacific Northwest due to weak ridging forecast over the northwestern CONUS. 
There are slightly enhanced probabilities of below normal temperatures for 
parts of Northern California due to the potential for frequent cloudiness and 
precipitation. Below normal temperatures are also favored for the Northern 
Rockies and Northern Plains in association with mean troughing forecast over 
east-central Canada.  There are slightly enhanced probabilities of above normal 
temperatures for parts of the interior southwestern CONUS and southern Plains 
northeastward to the Great Lakes due to predicted transient ridging. Below 
normal temperatures are slightly favored for parts of the southeast behind a 
trough predicted off the coast. 

The potential for enhanced Pacific flow leads to elevated probabilities of 
above normal precipitation across most of the western CONUS. The highest 
probabilities of above normal precipitation (grater than 60 percent) are 
indicated for parts of northern California as teleconnections from an upstream 
negative 500-hPa height anomaly center off the coast supports a wet pattern. 
Above normal precipitation is also favored for the east-central CONUS 
underneath predicted southerly mean low-level flow. Surface high pressure is 
forecast to build along the east coast, leading to enhanced probabilities of 
below normal precipitation across the Eastern Seaboard. Above normal 
precipitation is slightly favored for northwestern Alaska in association with a 
relatively weak trough forecast over the Bering Sea. Near to below normal 
precipitation is favored for the remainder of Alaska due to the strong ridge 
forecast over much of the mainland and the Panhandle.   

The official 6-10 day 500-hPa height blend consists of 30% of Today's 0z GFS 
Ensemble Mean centered on Day 8, 40% of Today's 6z GFS Ensemble Mean centered 
on Day 8, 5% of Today's operational 0z GFS centered on Day 8, 5% of Today's 
operational 6z GFS 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: Below average, 2 out of 5, due to 
some model and tool agreement, offset by large day to day variability, and weak 
500-hPa height anomalies across much of the CONUS.

8-14 DAY OUTLOOK FOR MAR 29 - APR 04, 2019 

For week-2, the highly amplified 500-hPa pattern across northern North America 
is forecast to continue, with persistent ridging across Alaska and a mean 
trough over east-central Canada. Broadly cyclonic flow is predicted farther to 
the south across much of the central and southern CONUS. 500-hPa anomalies are 
forecast to be positive across most of Alaska and the eastern third of the 
CONUS and negative across Northern California. Weak 500-hPa anomalies are 
indicated over the remainder of the CONUS. Model differences regarding details 
of individual features within a complex split-flow pattern forecast across 
North America lead to lower than normal confidence for much of the forecast 
domain during this 7 day period. 

Above normal temperatures are favored for Alaska underneath strong ridging. 
There are enhanced probabilities of below normal temperatures for the 
north-central CONUS in association with a mean trough over east-central Canada. 
Near to above normal temperatures are favored for much of the eastern third of 
the CONUS underneath predicted above normal heights. There are slightly 
enhanced probabilities of above normal temperatures for the southwestern CONUS 
and the Pacific Northwest due to predicted transient ridging.

Above normal precipitation is favored across much of the CONUS underneath 
broadly cyclonic flow. Conversely, there are enhanced odds of below normal 
precipitation for much of southern Alaska and the Pacific Northwest due to 
predicted ridging. Above normal precipitation is weakly favored for parts of 
northwestern mainland Alaska in association with a weak trough predicted over 
the Bering Sea 

The official 8-14 day 500-hPa height blend consists of: 40% of Today's 0z GFS 
Ensemble Mean centered on Day 11, 40% of Today's 6z GFS 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: Below average, 2 out of 5, due to 
generally weak 500-hPa anomalies across much of the CONUS and model differences 
regarding the evolution of individual features with a predicted split-flow 
pattern.

FORECASTER: Scott H

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 18.


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: 
19940328 - 19980318 - 19810311 - 19680301 - 19620401


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: 
19980317 - 19620331 - 19680228 - 19920311 - 19940330


6-10 DAY OUTLOOK TABLE
Outlook for Mar 27 - 31 2019

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

8-14 DAY OUTLOOK TABLE
Outlook for Mar 29 - Apr 04, 2019

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

$$