909
FXUS06 KWBC 061902
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Sun September 06 2026

6-10 DAY OUTLOOK FOR SEP 12 - 16 2026

The 500-hPa height forecast across North America is primarily driven by
mid-level amplification across the North Pacific, with the most dominant
feature being a +150 meter positive height anomaly center just to the south of
Alaska in the 6-10 day manual 500-hPa height blend, and above-normal heights
extending throughout much of Alaska. Troughs are depicted on either sides of
this feature, to the north across the Arctic, and to the south across the
eastern Pacific, but centered farther offshore the West Coast of the CONUS
compared to yesterday. However, model ensemble variability is high regarding
exact placement and amplitude of these features resulting in higher uncertainty
in how the pattern evolves downstream across the CONUS. The 0z ECMWF ensemble
along with its corresponding deterministic run are more robust regarding
ridging developing across the eastern CONUS by the middle of the period and
retrograding into the central CONUS by day-10. While the 0z GEFS and Canadian
depict a similar evolution, the positive mid-level height anomalies are weaker
across the East compared to the ECMWF ensemble. Uncertainty is tied to a
transient shortwave trough forecast to move across the Northern Tier of the
CONUS and into eastern Canada throughout the period. The GEFS and Canadian
ensembles are more amplified with this feature compared to the ECMWF ensemble,
which would limit the northward extent of the initial ridging. For the period
as a whole, the manual height blend depicts +30 meter above-normal heights
across much of the CONUS, with near-normal heights across the Northwest and
along the Canadian Border. Near-normal heights are forecast for Hawaii.

Despite the increased uncertainty in the evolving 500-hPa pattern, reforecast
and uncalibrated tools support high probabilities of above-normal temperatures
across most of the CONUS tied to increasing ridging. There is a notable
increase in probabilities across the eastern CONUS compared to yesterday as a
result of a lean toward the warmer ECMWF guidance and the analogs, with many
areas potentially having unseasonably warm temperatures into mid-September.
Conversely, shortwave troughing supports a period of relatively cooler
temperatures across portions of the Northwest into the Northern Plains where
near- to below-normal temperature chances are increased, supported by a
pronounced cool signal in the ECMWF reforecast tool. Ridging over Alaska favors
increased chances of above-normal temperatures over parts of the state
supported by the GEFS and ECMWF reforecast tools, although increased
precipitation may have a cooling effect across western and northern areas of
the Mainland, resulting in a higher likelihood of near-normal temperatures.
Above-normal temperatures are forecast across Hawaii tied to El Nino, with
chances increasing farther southeast.

There are high chances for above-normal precipitation across the interior
western CONUS due in part to low climatology, and enhanced troughing. Compared
to yesterday, dry signals have increased across the Pacific Northwest as the
troughing shifts farther eastward with time. However, to keep consistency with
yesterday`s forecast, near-normal precipitation is favored in the outlook.
Near- to below-normal precipitation is more likely across the eastern half of
the CONUS, with teleconnection analysis from the Gulf of Alaska ridge favoring
greater chances for below-normal. The uncalibrated ECMWF 6-10 day precipitation
totals are generally low (under a half inch) also supporting the tilt toward
below-normal over some areas, particularly from the Tennessee Valley to the
Mid-Atlantic. An enhanced mid-level pressure gradient and resultant onshore
flow favors elevated probabilities of above-normal precipitation across
Mainland Alaska. Below-normal precipitation is favored over Southeast Alaska,
underneath greater influence from ridging over the Gulf of Alaska. Above-normal
precipitation is favored across Hawaii tied to a continued active pattern
across the eastern and central Pacific, although any impacts from Hurricane
Lowell or the remnant of Hurricane Karina are likely to occur prior to the
start of the forecast period.

The official 6-10 day 500-hPa height blend consists of 35% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 40% of Today`s 0z European Ensemble Mean
centered on Day 8, and 25% 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
generally good model agreement on various synoptic features driving the
temperature and precipitation outlooks, offset by increasing ensemble
variability and some differences regarding timing.

8-14 DAY OUTLOOK FOR SEP 14 - 20 2026

During week-2, dynamical models are in good agreement regarding broad ridging
building across the eastern and central CONUS. While the initial ridging is
forecast to develop over the East, slight retrogression into the central CONUS
is predicted by the middle of the period. The 0z ECMWF ensemble is most robust
indicating +60 meter positive height anomalies across portions of the eastern
CONUS at the outset of the period, but is also the quickest to retrograde west.
The 0z GEFS and Canadian ensembles have a weaker initial ridge over the East
and  depict greater amplitude by the middle of the period when the ridge is
more centered over the Plains. As mentioned in the 6-10 day discussion, the
GEFS, and more so the Canadian ensemble, depict a more amplified trough moving
across eastern Canada which results in a lowering of the mid-level heights
across the East. Ridging and associated above-normal heights are forecast to
persist over most of Alaska, with troughs well offshore the West Coast of the
CONUS and over the Arctic. The 0z ECMWF ensemble depicts above-normal 500-hPa
heights spreading into the West, with the GEFS and Canadian ensembles
persisting weak troughing near the coast. For the week-2 period as a whole, +30
meter positive height anomalies are depicted across much of the CONUS, with
closer to normal heights near the West Coast and across the Northeast. Near- to
slightly above-normal heights are forecast across Hawaii.

Probabilities for above-normal temperatures are increased across much of the
CONUS underneath expanding mid-level ridging, with support from most forecast
tools. There continues to be higher uncertainty over the Northern Plains, Upper
Midwest, and Northeast where the expanding ridge is forecast to compete with
troughing over eastern Canada resulting in a forecast of near-normal
temperatures, with the GEFS and Canadian ensembles indicating a cooler forecast
compared to the warmer ECMWF ensemble. Also tied to the more westward
progression of the ridge is a trend toward warmer temperatures across the West
in week-2, with both the reforecast and uncalibrated ECMWF and GEFS ensembles
supporting increased probabilities of above-normal temperatures. Above-normal
temperatures chances remain elevated across Alaska and Hawaii for the same
reasoning discussed in the 6-10 day outlook.

The precipitation forecast for week-2 is largely similar to that of the 6-10
day period. Enhanced tropical moisture is forecast to continue to advect into
the West where, combined with low precipitation climatology, above-normal
precipitation odds are increased over most areas. Precipitation signals break
down across much of the eastern half of the CONUS where mid-level ridging
combined with low amounts in the uncalibrated model ensembles support enhanced
chances for near- to below-normal precipitation over most areas, with
additional support for below-normal in the analogs. Above-normal precipitation
is weakly favored across portions of the Southeast, along the Gulf Coast, and
the Northeast. A tilt toward enhanced probabilities for above-normal
precipitation continues over Mainland Alaska, although odds are decreased
relative to the 6-10 day period. Slightly enhanced odds of below-normal
precipitation remain favored for Southeast Alaska underneath the mid-level
ridge over the Gulf of Alaska. Above-normal precipitation remains forecast for
Hawaii due to a continued active storm track and potential for additional
tropical activity over the Eastern and Central Pacific basins.

The official 8-14 day 500-hPa height blend consists of: 35% of Today`s 0z GFS
Ensemble Mean centered on Day 11, 40% of Today`s 0z European Ensemble Mean
centered on Day 11, and 25% of Today`s 0z Canadian Ensemble Mean centered on
Day 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Average, 3 out of 5, due to good
model agreement regarding expanding ridging over the central CONUS and
increased confidence for above-normal temperatures, offset by greater
uncertainty across the West and Northeast, as well as low precipitation signals
across the CONUS.

FORECASTER: Thomas Collow

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:
20190917 - 20220918 - 20050909 - 20240821 - 20240920


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:
20240822 - 20190917 - 20240912 - 20050907 - 20220918


6-10 DAY OUTLOOK TABLE
Outlook for Sep 12 - 16 2026

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



8-14 DAY OUTLOOK TABLE
Outlook for Sep 14 - 20 2026

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

                           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.

$$