836
FXUS06 KWBC 091905
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Tue September 09 2025

6-10 DAY OUTLOOK FOR SEP 15 - 19 2025

The recent ECMWF, GEFS, and Canadian ensemble means agree on the 500-hPa height
pattern forecast over North America and surrounding regions during the 6-10 day
period, with only small variations in the pattern. Models predict a trough and
associated negative 500-hPa height anomalies over the North Pacific to the
south of the eastern Aleutian Islands and the Alaska Peninsula in the 6-10 day
period mean. Models predict westward retrogression of the trough and negative
500-hPa height anomalies from the Gulf of Alaska early in the period to south
of the eastern Aleutians by the middle of the period, followed by rapid
deamplification. An amplified ridge is predicted across Canada in the 6-10 day
period, extending into the northern central contiguous United States (CONUS).
In the manual blend of model forecasts, positive 500-hPa height anomalies are
predicted across most of the CONUS in the 6-10 day period, while weak troughing
and near zero mid-level height anomalies are predicted over the Southeast.

Below normal temperatures are favored for the west coast of Mainland Alaska
under anomalous northerly mid-level flow, while above normal temperatures are
more likely for southern and eastern Mainland Alaska and Southeast Alaska under
mean positive 500-hPa height anomalies and southerly flow.  In the 6-10 day
period, above normal temperatures are likely across most of the CONUS excluding
the Eastern Seaboard and parts of the West, influenced by the amplified ridge
and positive 500-hPa height anomalies. Near to below normal temperatures are
favored for the Eastern Seaboard in the 6-10 day period, related to the
predicted trough and weak 500-hPa height anomalies. Above normal temperatures
are likely for Hawaii, consistent with the consolidation of calibrated ECMWF
and GEFS forecasts and above average sea surface temperatures across much of
the region.

Below normal precipitation is favored for much of the west coast of Mainland
Alaska, under anomalous northerly flow. Above normal precipitation is favored
for southern and eastern Mainland Alaska as well as Southeast Alaska, ahead of
a predicted trough. As mid-level heights rise over the northwestern CONUS,
precipitation is predicted to decrease leading to enhanced probabilities of
below normal precipitation along the Pacific Northwest coast. Above normal
precipitation is favored in the 6-10 day period for much of the interior West,
including the Southwest, the Northern Rockies, and the Northern Plains,
consistent with most model forecast tools and the consolidation. Near normal
precipitation is favored in parts of California and Nevada, where there is a
dry climatology and model precipitation signals are small. Below normal
precipitation is favored for East Texas, the Lower Mississippi Valley, the Ohio
Valley, the Great Lakes region, and northern New England, under anomalous
northerly flow ahead of the predicted ridge and consistent with most model
precipitation forecasts. Probabilities for above normal precipitation are
slightly enhanced for South Florida in the 6-10 day period, consistent with the
precipitation consolidation. Above normal precipitation is favored for most of
Hawaii excluding the Big Island, consistent with the Auto Blend of forecast
tools and the precipitation consolidation.

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 between ensemble model forecasts of an amplified mid-level
height pattern, offset by some differences among temperature and precipitation
forecast tools for some areas.

8-14 DAY OUTLOOK FOR SEP 17 - 23 2025

Canadian, ECMWF, and GEFS ensemble mean forecasts for the 500-hPa height
pattern over North America remain in general agreement during the 8-14 day
period, while the pattern evolves and somewhat deamplifies. A weak trough
persists over the eastern Aleutian Islands but deamplifies during the 8-14 day
period in all ensemble mean forecasts. An amplified ridge and associated
positive 500-hPa height anomalies persist over Canada through the 8-14 day
period, with positive 500-hPa height anomalies extending southward across most
of the CONUS. A weak trough and slightly negative 500-hPa height anomalies
persist over the southeastern CONUS in the 8-14 day period manual blend with
some variations among the Canadian, ECMWF and GEFS ensemble means.

Above normal temperatures are likely over a larger area of Mainland and
Southeast Alaska in the 8-14 day period, excluding parts of northwestern
Mainland Alaska, as the predicted trough and negative 500-hPa height anomalies
to the south of the state deamplify and positive 500-hPa height anomalies
increase in magnitude and extent across Mainland Alaska. Above normal
temperatures are favored across almost the entire CONUS, excluding small areas
of the Central Rockies and the central East Coast, under positive 500-hPa
height anomalies. Areas of enhanced probabilities of near normal temperatures
for the East Coast are associated with a persistent trough over the Southeast.
Above normal temperatures are likely for Hawaii, consistent with the
temperature consolidation and above average sea surface temperatures around the
northwestern islands.

Near normal precipitation is slightly favored for northwestern Mainland Alaska
under primarily anomalous northerly flow in the evolving circulation pattern.
Above normal precipitation continues to be favored for southern and eastern
Mainland Alaska and northern areas of Southeast Alaska in the 8-14 day period,
consistent with most dynamical model forecasts. Below normal precipitation
continues to be slightly favored for parts of the Oregon and Washington coasts
in week 2, under positive 500-Pa height anomalies and also consistent with most
model forecast tools. Above normal precipitation is favored from the Southwest,
the Rocky Mountains, and the Northern and Central Plains, consistent with the
precipitation consolidation and most model tools. Near to below normal
precipitation is slightly favored for most of the eastern CONUS, under
anomalous northerly flow ahead of the predicted ridge. Above normal
precipitation is slightly favored for the Southeast Atlantic and the southern
Mid-Atlantic coasts, consistent with the consolidation. Above normal
precipitation is slightly favored for most islands of Hawaii, excluding the Big
Island, consistent with the Auto forecast blend.

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: Near average, 3 out of 5, due to
good overall agreement on the mid-level height forecast, offset by a
deamplifying pattern and weak signals in the precipitation tools for many areas.

FORECASTER: D Collins

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:
20070913 - 19860907 - 19730916 - 19650822 - 19940828


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:
20070913 - 19730916 - 19940828 - 19980919 - 19650821


6-10 DAY OUTLOOK TABLE
Outlook for Sep 15 - 19 2025

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



8-14 DAY OUTLOOK TABLE
Outlook for Sep 17 - 23 2025

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

$$