469
FXUS06 KWBC 101931
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Thu September 10 2026

6-10 DAY OUTLOOK FOR SEP 16 - 20 2026

Dynamical models are in good agreement regarding the 500-hPa pattern across
North America during the 6-10 day period. The 0z GEFS, ECMWF, and Canadian
ensembles all depict an anomalous mid-level ridge across the south-central and
eastern CONUS at the outset of the period. This feature is forecast to
retrograde as shortwave troughing digs into the Great Lakes and Northeast by
the second half of the period. Given this evolution, the manual height blend
indicates above-normal heights across nearly all of the CONUS, with a broad
area of +60 meter positive height anomalies from the Great Basin to the
Tennessee Valley. Across the north Pacific, anomalous ridging is forecast to
shift eastward from the Gulf of Alaska into western Canada, with a +150 meter
positive height anomaly center near Southeast Alaska in the manual blend. The
inland progression of the ridge axis combined with weakening troughing off the
coast of northern California favors additional mid-level height rises across
western North America, and broader mid-level troughing developing to the south
of Alaska. Above-normal heights are forecast across Hawaii.

A pattern transition is forecast to occur across the eastern U.S. throughout
the period. The early portion of the period is forecast to be on the warmer
side with temperatures generally 5-10 deg F above-average. However, as the
ridge shifts more west, and troughing amplifies over eastern Canada, a fairly
pronounced temperature drop is predicted to occur, and a period of fall-like
weather is becoming increasingly likely. The forecast continues to tilt toward
above-normal temperatures for much of the East given the warmth early on, with
near- to slightly below-normal temperatures more likely across the Upper
Midwest into the Northeast. While cooler trends are predicted in the East, the
West has trended warmer given both the CONUS ridge shifting westward and the
Gulf of Alaska ridge moving east, setting up a high amplitude ridge axis over
much of the western U.S. This is reflected in the GEFS and ECMWF reforecast and
uncalibrated tools, which depict high probabilities for above-normal
temperatures. While the forecast leans warmer, probabilities for above-normal
are scaled back somewhat compared to the guidance to account for some
continuity with yesterday. High probabilities for above-normal temperatures are
forecast across most of Alaska underneath the aforementioned ridge, with the
highest probabilities over Southeast Alaska, with areas of far western and
northern Mainland Alaska favoring a tilt toward near- to below-normal
temperatures. Above-normal temperatures are strongly favored across Hawaii tied
to above-normal sea surface temperatures (SSTs) and El Nino conditions.

Increased tropical moisture advection continues to result in high probabilities
for above-normal precipitation across much of the West. While the highest
probabilities (greater than 50 percent) are focused across the Four Corners,
due in part to low climatology. Some of this moisture is forecast to be
entrained into a frontal system moving across the Midwest and eventually the
Northeast supporting a broadly enhanced area with probabilities of above-normal
precipitation exceeding 40 percent. Enhanced probabilities for below-normal
precipitation are favored across the Pacific Northwest and Southeast Alaska
underneath ridging, and supported by the GEFS and ECMWF reforecast and
uncalibrated tools. Increasing troughing to the south of Alaska later in the
period favors increasing chances for above-normal precipitation across the
Mainland and Aleutians. Continued active tropical activity across the Eastern
and Central Pacific Basins favors elevated odds of above-normal precipitation
across Hawaii.

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 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: Average, 3 out of 5, due to good
model agreement regarding the evolution of the mid-level height pattern across
the forecast domain, offset by a transitioning temperature pattern over many
areas of the CONUS.

8-14 DAY OUTLOOK FOR SEP 18 - 24 2026

The GEFS, ECENS, and CMCE are in good agreement that an amplified 500-hPa ridge
over western North America leads to a deepening trough downstream across
eastern North America early in week-2. Compared to yesterday, these ensemble
mean solutions are more amplified with this trough and thus the coverage of
favored near normal temperatures or elevated below-normal probabilities have
increased across the Midwest, Mid-Atlantic, and Northeast. Following a forecast
period of cooler-than-normal temperatures across the Northern Great Plains
preceding week-2, the GEFS and ECENS both depict a transition to above-normal
temperatures by day 10 as the mid-level ridge/trough pattern shifts eastward
with time. Therefore, the week-2 outlook leans on the warmer side for the
Northern Great Plains. Although above-normal temperatures remain favored for
the Southern Great Plains, Lower Mississippi Valley, and Southeast into late
September, probabilities are lower today as the amplified eastern North America
trough is expected to result in a cold front progressing into these areas.
Elsewhere across the interior western CONUS, forecast confidence is high for
above-normal temperatures based on good model agreement and consistency.

Enhanced low to mid-level moisture from the eastern Pacific is forecast to
persist over the Southwest and Central to Southern Rockies. Dynamical model
output and the analog tool derived from the manual 500-hPa height blend support
elevated above-normal precipitation probabilities for those areas along with
southern California. The primary driver for any enhanced precipitation for the
central and eastern CONUS is likely to be a cold front shifting south and east
at the beginning of week-2. The outlook leans slightly towards the wetter side
for parts of the Southeast. Given the model trend towards a faster frontal
passage, near normal precipitation is favored for much of the remainder of the
central and eastern CONUS, while surface high pressure leads to a slight tilt
towards below-normal precipitation from the western and central Great Lakes
south to the Ohio River.

An amplified 500-hPa trough over the Aleutians with associated southwesterly
surface flow increases the chance for above-normal precipitation and
temperatures across much of Alaska. Closer to a nearby western North American
ridge, near to below-normal precipitation is more likely for far southern areas
of southeastern Alaska.

Tropical Storm Norbert is forecast to track westward across the East Pacific,
between 10-15N latitude. Although there is large ensemble spread on its
eventual track next week, the proximity of Norbert along with a disturbance,
currently southeast of the Hawaiian Islands, favors above-normal precipitation
throughout Hawaii. Please refer to the National Hurricane Center for the latest
updates. The GEFS and ECENS support large above-normal temperature
probabilities.

The official 8-14 day 500-hPa height blend consists of: 30% of Today`s 0z 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
uncertainty on the amplitude of a trough over eastern North America and its
influence on the temperature and precipitation outlooks.

FORECASTER: Collow/Pugh

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
September 17.


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:
20050909 - 20220919 - 20240821 - 20190918 - 20140825


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:
20050909 - 20220918 - 20240820 - 20020903 - 20140825


6-10 DAY OUTLOOK TABLE
Outlook for Sep 16 - 20 2026

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



8-14 DAY OUTLOOK TABLE
Outlook for Sep 18 - 24 2026

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    N     OREGON      A    N     NRN CALIF   A    N
SRN CALIF   A    A     IDAHO       A    N     NEVADA      A    A
W MONTANA   A    N     E MONTANA   A    N     WYOMING     A    A
UTAH        A    A     ARIZONA     A    A     COLORADO    A    A
NEW MEXICO  A    A     N DAKOTA    A    N     S DAKOTA    A    N
NEBRASKA    A    N     KANSAS      A    N     OKLAHOMA    A    N
N TEXAS     A    N     S TEXAS     A    N     W TEXAS     A    A
MINNESOTA   N    N     IOWA        N    N     MISSOURI    N    N
ARKANSAS    A    N     LOUISIANA   A    N     WISCONSIN   N    B
ILLINOIS    N    B     MISSISSIPPI A    N     MICHIGAN    B    B
INDIANA     N    B     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        N    N     NEW JERSEY  N    N     W VIRGINIA  N    N
MARYLAND    N    N     DELAWARE    N    N     VIRGINIA    N    N
N CAROLINA  N    N     S CAROLINA  A    N     GEORGIA     A    N
FL PNHDL    A    N     FL PENIN    A    N     AK N SLOPE  N    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    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.

$$