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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 Tue May 21 2019

6-10 DAY OUTLOOK FOR MAY 27 - 31 2019

Today's model solutions remain in very good agreement in terms of an amplified 
500-hPa height pattern in the 6-10 day period. A trough is forecast over the 
Bering Sea and the north central Pacific, while a ridge is predicted over 
northwestern Canada, extending to mainland Alaska. In the southern stream, a 
persistent trough associated with negative height anomalies is favored for the 
West, while ridging and above normal heights are forecast for much of the East. 

Troughing in the western CONUS favors high confidence for below normal 
temperatures, particularly over parts of the Rockies and the Great Basin. The  
exception being parts of the Northwest, above normal temperatures are favored 
due to avove normal heighs. Conversely, to the east, high probabilities exist 
for above normal temperatures underneath forecast ridging. Very warm 
temperatures (above 100 for day 6-7) are also possible for the southeastern 
CONUS during this period. Above normal heights forecast over much of Alaska 
enhances the likelihood of above normal temperatures for most of the state, 
except for parts of the south coast of mainland Alaska, where below normal 
temperature probabilities are favored.

Above normal precipitation probabilities remain elevated for most of the West 
due to persistent troughing. Ridging over the East Pacific favors increased 
below normal precipitation probabilities for some parts of the Pacific 
Northwest and parts of the Alaska Panhandle. Ridging in the East, combined with 
surface high pressure off the Southeast coast, favors increased below normal 
precipitation probabilities over the Southeast and the Mid-Atlantic. Over the 
Central CONUS, anomalous southerly low-level flow increases the likelihood of 
above normal precipitation for much of the Plains and the Great Lakes region, 
extending to the Northeast. A series of shortwave troughs over the Bering Sea 
favors increased probabilities of above normal precipitation over mainland 
Alaska and the Aleutians.

The official 6-10 day 500-hPa height blend consists of 20% of Today's 0z GFS 
Ensemble Mean centered on Day 8, 20% of Today's 6z GFS Ensemble Mean centered 
on Day 8, 20% of Today's GFS Superensemble Mean centered on Day 8, 20% of 
Today's 0z European Ensemble Mean centered on Day 8, and 20% of Yesterday's 12z 
European Ensemble Mean centered on Day 7 
 

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Above average, 4 out of 5, due to 
an amplified pattern for late-May, and good agreement between models and tools.

8-14 DAY OUTLOOK FOR MAY 29 - JUN 04, 2019 

During the week-2 period, the forecast 500-hPa height pattern is positioned 
similarly to the 6-10 day period, except a bit less amplified, due to increased 
uncertainty with lead time. 

The resulting temperature probability forecast during the week 2 period is very 
similar to the 6-10 day period, with increased below normal probabilities in 
the West, except for the Pacific coast and parts of the Northwest and increased 
above normal probabilities in the East. Due to the forecast above normal 
heights over mainland Alaska, increased above normal temperature probabilities 
are highlighted for northwestern mainland Alaska and the Aleutians, while below 
normal temperature probabilities are favored for the south coast of Alaska. 

The precipitation probability forecast during the week-2 period is also very 
similar to the 6-10 day period, though probabilities are generally lower. 
Forecast troughing favors above normal precipitation for much of the western 
CONUS. Continued southerly low-level flow into parts of the Southern Plains, 
the Great Lakes region and the Northeast favors elevated chances of above 
normal precipitation in those areas. Below normal precipitation probabilities 
are favored for parts of the Southeastern CONUS, the northern Plain and the 
Northwest consistent with the consolidation forecast tool. Increased above 
normal precipitation probabilities remain favored for mainland Alaska, the 
Aleutians, and parts of the Alaska panhandle.

The official 8-14 day 500-hPa height blend consists of: 20% of Today's 0z GFS 
Ensemble Mean centered on Day 11, 20% of Today's 6z GFS Ensemble Mean centered 
on Day 11, 20% of Today's GFS Superensemble Mean centered on Day 11, 20% of 
Today's 0z Canadian Ensemble Mean centered on Day 11, and 20% of Yesterday's 
12z Canadian Ensemble Mean centered on Day 10 


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Average, 3 out of 5, due to good 
agreement among the ensemble mean 500-hPa height fields and temperature and 
precipitation tools, with some uncertainty regarding the potential for the 
amplified pattern to weaken later in the period.

FORECASTER: Qin Z

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 
June 20.


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: 
19570518 - 19530511 - 19900529 - 19950510 - 19790508


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: 
19570518 - 19530511 - 19530516 - 19540602 - 19900528


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

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

8-14 DAY OUTLOOK TABLE
Outlook for May 29 - Jun 04, 2019

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

$$