407
FXUS06 KWBC 221902
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 22 2026

6-10 DAY OUTLOOK FOR SEP 28 - OCT 02, 2026

The 0Z ECMWF, GEFS, and Canadian ensemble model forecasts predict a ridge and
positive 500-hPa height anomalies over the western and central Aleutian
Islands. All models predict a trough downstream over southern Mainland Alaska
and the northeastern Pacific, with negative 500-hPa height anomalies extending
into western Canada. Negative 500-hPa height anomalies extend into the Pacific
Northwest in the GEFS and ECMWF ensemble means. This trough is predicted to
amplify southward during the middle of the 6-10 day period before contracting
later in the period. Although models agree on the prediction of this trough
over the northeastern Pacific, model height forecast differences are
significant over the contiguous United States (CONUS). The manual height blend
is based on the 0Z ECMWF, GEFS, and Canadian model 500-hPa height forecasts,
weighting the ECMWF ensemble mean greater due to recent model skill. The manual
blend predicts negative 500-hPa height anomalies over most of the Pacific
Northwest during the 6-10 day period, ahead of the trough. The ECMWF ensemble
mean forecast predicts anomalous mid-level ridging and positive 500-hPa height
anomalies extending from the central Rockies to the northern central and
northeastern CONUS, with a positive anomaly center over northern Quebec, while
the GEFS and Canadian ensemble mean forecasts predict less extensive coverage
of the CONUS with positive 500-hPa height anomalies. A trough and negative
500-hPa height anomalies are predicted over the Eastern Seaboard early in the
6-10 day period by all ensemble means. A shortwave trough develops over the
northern central CONUS in all models around day 8. This trough amplifies
significantly and progresses eastward in the Canadian ensemble mean, while the
ECMWF model predicts increasing positive 500-hPa height anomalies over the
northern central CONUS and the Midwest later in the period. A tropical system
is predicted to pass near Southeastern islands of Hawaii by dynamical model
forecasts.

Above normal temperatures are favored for most of the Aleutian Islands, under
predicted positive 500-hPa height anomalies. Below normal temperatures are
slightly favored for the far northwestern and central west coast of Mainland
Alaska, consistent with the consolidation of calibrated ECMWF and GEFS
forecasts. Above normal temperatures are favored for eastern Mainland Alaska,
under predicted anomalous southerly flow. Under the predicted ridge and
slightly positive 500-hPa height anomalies, above normal temperatures are
favored across most of the CONUS, consistent with the temperature
consolidation. Near normal temperatures are favored for a large area of the
northwestern CONUS, while below normal temperatures are slightly favored for
parts of Washington and Oregon, consistent with the consolidation and ahead of
the predicted trough over the northeastern Pacific. Above normal temperatures
are favored for Hawaii with higher probabilities for the Big Island, consistent
with the calibrated ECMWF temperature forecast.

Above normal precipitation is favored for most of the Aleutians, consistent
with the automated blend of forecast tools and the consolidation of calibrated
ECMWF and GEFS forecasts. Precipitation signals are weak or inconsistent across
much of Mainland Alaska, leading to a forecast of near normal. Above normal
precipitation is slightly favored for southeastern Mainland Alaska and there is
enhanced probability of above normal precipitation for Southeast Alaska, ahead
of the predicted trough. Above normal precipitation is also favored for the
Pacific Northwest and slightly favored for the northern Rockies, ahead of the
trough over the northeastern Pacific. Probabilities of above normal
precipitation for the Southwest are enhanced, exceeding 50 percent in some
areas, as models predict enhanced moisture flow from the Eastern Pacific into
the region. Above normal precipitation is favored for the central and southern
Rockies, the Great Plains, the Mississippi Valley, and the Southeast, while
near normal precipitation is favored for much of the northeastern CONUS,
consistent with the precipitation consolidation. Above normal precipitation is
favored for Hawaii, with the prediction of a potential low pressure system near
the island chain.

The official 6-10 day 500-hPa height blend consists of 30% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 50% 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: About average, 3 out of 5, due to
good agreement between model forecasts of the mean large-scale mid-level height
pattern, offset by differences among model ensemble mean height forecasts for
the CONUS.

8-14 DAY OUTLOOK FOR SEP 30 - OCT 06, 2026

The overall predicted 500-hPa height pattern is relatively similar in the 8-14
day period ensemble model forecasts, with some evolution of the pattern and
deamplification relative to the 6-10 day period forecast. A ridge and positive
500-hPa height anomalies persist over parts of the western Aleutians while
deamplifying in the 8-14 day period in all model forecasts, with a trough and
negative 500-Pa height anomalies over parts of southern Mainland Alaska, the
northeastern Pacific, and western Canada. While all model week-2 500-hPa height
forecasts are similar to their respective 6-10 day forecasts, there are
significant differences in the ECMWF, GEFS and Canadian ensemble means. The
manual blend continues to weight the ECMWF model greater, predicting positive
500-hPa height anomalies that extend from the central Rockies to the northern
central CONUS and Great Lakes region. Weak negative 500-hPa heights are
predicted over parts of the Pacific Northwest in the 8-14 day period manual
blend, while weak 500-hPa height anomalies are predicted over the southeastern
CONUS.

Above normal temperatures continue to be favored across most of the Aleutians
in week 2, under positive 500-hPa height anomalies. Below normal temperatures
are favored for the western coastal Mainland, under troughing and consistent
with the temperature consolidation. Above normal temperatures are favored for
eastern Mainland Alaska and Southeast Alaska, under anomalous southerly flow.
Consistent with the temperature consolidation, above normal temperatures are
favored across nearly the entire CONUS in week 2, as a predicted ridge persists
with positive 500-hPa height anomalies from the central Rockies to the northern
central CONUS and parts of the northeastern CONUS. Near normal temperatures are
favored for the Pacific Northwest including northern California, ahead of a
predicted trough. Above normal temperatures are favored for Hawaii with greater
probabilities for the Big Island, consistent with the temperature
consolidation.

Above normal precipitation continues to be favored across most of the Aleutians
in week 2, consistent with the automated blend of forecast tools. Precipitation
signals are weak across most of Mainland Alaska, favoring near normal. Above
normal precipitation is favored for southeastern Mainland Alaska, Southeast
Alaska, and parts of the northwestern CONUS, ahead of the predicted trough over
the northeastern Pacific. Above normal precipitation is favored for the
Southwest, with continued moisture flow from the Eastern Pacific. Near normal
precipitation is forecast in climatologically arid and semi-arid regions of the
West where the precipitation consolidation anomalies are small. Consistent with
anomaly forecasts from the precipitation consolidation, above normal
precipitation is favored for the central and eastern CONUS, with probabilities
exceeding 50 percent for the western and central Gulf Coast region. Above
normal precipitation is favored for Hawaii, consistent with the calibrated
ECMWF precipitation forecast.

The official 8-14 day 500-hPa height blend consists of: 20% of Today`s 0z GFS
Ensemble Mean centered on Day 11, 60% 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: About average, 3 out of 5, due to
good agreement between model forecasts of the mean large-scale mid-level height
pattern, offset by continued differences among model ensemble mean height
forecasts for the CONUS.

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 (gray, "N") normal.
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 (gray, "N")
normal. 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
October 15.


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:
20200920 - 20250910 - 20240904 - 20250920 - 20220904


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:
20240901 - 20171004 - 20040926 - 20200919 - 20240906


6-10 DAY OUTLOOK TABLE
Outlook for Sep 28 - Oct 02, 2026

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



8-14 DAY OUTLOOK TABLE
Outlook for Sep 30 - Oct 06, 2026

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  N    A     OREGON      N    A     NRN CALIF   A    N
SRN CALIF   A    N     IDAHO       A    N     NEVADA      A    N
W MONTANA   A    N     E MONTANA   A    A     WYOMING     A    N
UTAH        A    N     ARIZONA     A    A     COLORADO    A    A
NEW MEXICO  A    A     N DAKOTA    A    A     S DAKOTA    A    A
NEBRASKA    A    A     KANSAS      A    A     OKLAHOMA    A    A
N TEXAS     A    A     S TEXAS     A    A     W TEXAS     A    A
MINNESOTA   A    A     IOWA        A    A     MISSOURI    A    A
ARKANSAS    A    A     LOUISIANA   A    A     WISCONSIN   A    A
ILLINOIS    A    A     MISSISSIPPI A    A     MICHIGAN    A    A
INDIANA     A    A     OHIO        A    A     KENTUCKY    A    A
TENNESSEE   A    A     ALABAMA     A    A     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    A     S CAROLINA  A    A     GEORGIA     A    A
FL PNHDL    A    A     FL PENIN    A    A     AK N SLOPE  N    N
AK ALEUTIAN N    N     AK WESTERN  N    N     AK INT BSN  A    N
AK S INT    N    A     AK SO COAST A    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.

$$