902
FXUS06 KWBC 011907
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Mon September 01 2025

6-10 DAY OUTLOOK FOR SEP 07 - 11 2025

The ECMWF, GEFS and Canadian ensemble models broadly agree on the 500-hPa
height pattern over North America and surrounding regions during the 6-10 day
period, with only minor variations among the models in terms of amplitude and
phase of predicted wave features. The manual height blend is based on ensemble
means, weighing the ECMWF model greater due to recent model anomaly correlation
skill. The manual blend shows a ridge and above normal 500-hPa heights over
Alaska, western and central Canada, and the western and central Contiguous U.S.
(CONUS), while a trough with below normal 500-hPa heights are predicted over
the eastern CONUS. Another trough is forecast along the West Coast. Near to
slightly above normal 500-hPa heights are predicted across Hawaii.

Above normal temperatures are favored for the Aleutians, the Alaska Panhandle,
most of Mainland Alaska, and most of the western CONUS (except for parts of
California and Nevada, where below normal temperatures are favored, due to a
trough predicted along the West Coast)  in association with predicted broad
anomalous ridging and above normal 500-hPa heights over these areas.
Conversely, the trough forecast across the eastern CONUS, especially early in
the period, favors below normal temperatures over most of the eastern and
central CONUS, except for the Gulf Coast states where above normal temperatures
are favored due to subtropical ridging to the south of a mean frontal boundary,
consistent with most of the dynamic temperature forecast tools. Above normal
temperatures are favored for Hawaii due to slightly above normal 500-hPa
heights and above normal sea surface temperatures in the adjacent Pacific.

Above normal precipitation is forecast over most of the western and central
CONUS, consistent with the autoblend and consolidated precipitation forecast
tools. Influxes of monsoonal moisture across the Southwest combined with a
stationary frontal boundary across the southern High Plains are the main
drivers for this predicted active period. Conversely, near to below normal
precipitation is favored across most of the eastern CONUS (except for the
southern Atlantic Coast and the Gulf Coast states where above normal
precipitation chances are elevated ahead of the predicted mean trough axis) due
to predicted surface high pressure associated with a cool stable Canadian
airmass. Below normal precipitation is also favored for Southeast Alaska,
associated with anomalous ridging forecast over western Canada. Above normal
precipitation is more likely across most of the remainder of Alaska ahead of a
trough predicted over the Bering Sea. Above  normal precipitation is favored
for Hawaii, supported by the consolidation precipitation forecast tool.

The official 6-10 day 500-hPa height blend consists of 30% of Today`s 6z GFS
Ensemble Mean centered on Day 8, 40% of Today`s 0z European Ensemble Mean
centered on Day 8, and 30% 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
good agreement among todays ensemble means.

8-14 DAY OUTLOOK FOR SEP 09 - 15 2025

Ensemble mean forecasts for the 500-hPa circulation pattern over North America
remain in general agreement and a transition in the 500-hPa pattern is well
underway across much of the country during the 8-14 day period. As time
progresses, a much more zonal regime takes hold across much of the CONUS.  In
the manual blend of model forecasts, a weak anomalous trough is predicted over
the Aleutians, while a ridge and above normal 500-hPa heights are forecast over
Alaska, Canada and north-central and northeastern CONUS throughout the period.
An anomalous trough is forecast over the West Coast. Generally near normal
heights are forecast for Hawaii throughout the period.

Near to above normal temperatures are likely for most of Alaska due to
persistent ridging and above normal heights. Enhanced probabilities of above
normal temperatures are also forecast across much of the central CONUS, due to
predicted ridging and above normal 500-hPa heights. Conversely, below normal
temperatures are favored for the northeastern CONUS due to predicted anomalous
troughing early in the period. Below normal temperatures are also favored over
portions of California, Nevada, Oregon, and Idaho, under a predicted trough
over the West Coast, supported by most of the temperature forecast tools. Above
normal temperatures are more likely for the southeastern CONUS, to the south of
a predicted frontal boundary and consistent with above normal SSTs in the
adjacent Atlantic and Gulf waters. Above normal temperatures are likely for
Hawaii, due largely to observed above normal SSTs in the adjacent Pacific.

A wet pattern is favored for most of the northwestern and north-central CONUS,
due to a trough trough predicted over the West Coast. Above normal
precipitation chances are elevated along the Gulf and Southeast coasts around
the periphery of a predicted anomalous trough early in the period. Modestly
enhanced chances of below normal precipitation is forecast for parts of the
northeastern CONUS due to predicted surface high pressure early in the period.
These enhanced below normal precipitation chances were kept low due to the
potential transition to a wetter pattern toward the end of week-2. Above normal
precipitation is favored for most of Mainland Alaska and the Alaska Peninsula
ahead of troughing forecast over the Aleutians. Above normal precipitation is
favored across the Hawaiian islands, consistent with the consolidation
precipitation forecast tool.

The official 8-14 day 500-hPa height blend consists of: 30% of Today`s 6z GFS
Ensemble Mean centered on Day 11, 40% of Today`s 0z European Ensemble Mean
centered on Day 11, and 30% 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
uncertainties surrounding a predicted transitional 500-hPa flow pattern across
much of North America.

FORECASTER: Luke H

Notes:


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
September 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:
19630827 - 19790821 - 19610819 - 19810825 - 19870903


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:
19630827 - 19610818 - 19870903 - 19790820 - 19510822


6-10 DAY OUTLOOK TABLE
Outlook for Sep 07 - 11 2025

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    A     OREGON      A    A     NRN CALIF   N    A
SRN CALIF   B    N     IDAHO       A    A     NEVADA      B    A
W MONTANA   A    A     E MONTANA   A    A     WYOMING     A    A
UTAH        A    A     ARIZONA     A    A     COLORADO    A    A
NEW MEXICO  A    A     N DAKOTA    A    A     S DAKOTA    A    A
NEBRASKA    B    A     KANSAS      B    A     OKLAHOMA    B    A
N TEXAS     B    A     S TEXAS     A    A     W TEXAS     B    A
MINNESOTA   B    N     IOWA        B    N     MISSOURI    B    N
ARKANSAS    B    N     LOUISIANA   A    N     WISCONSIN   B    B
ILLINOIS    B    B     MISSISSIPPI B    N     MICHIGAN    B    B
INDIANA     B    B     OHIO        B    B     KENTUCKY    B    B
TENNESSEE   B    B     ALABAMA     B    N     NEW YORK    B    B
VERMONT     B    B     NEW HAMP    B    B     MAINE       B    B
MASS        B    B     CONN        B    B     RHODE IS    B    N
PENN        B    B     NEW JERSEY  B    B     W VIRGINIA  B    B
MARYLAND    B    B     DELAWARE    B    N     VIRGINIA    B    N
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    N     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 Sep 09 - 15 2025

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

$$