761
FXUS06 KWBC 021903
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 02 2025

6-10 DAY OUTLOOK FOR SEP 08 - 12 2025

The GEFS, ECENS, and CMCE are in good agreement that the highly amplified and
stable longwave pattern becomes more zonal during the second week of September.
This pattern transition is likely to bring a warming trend to the eastern and
central contiguous U.S. (CONUS) after a prolonged stretch of below-normal
temperatures. However, multi-model ensemble mean solutions depict below-normal
temperatures persisting through day 7 or 8 for those areas and the 6-10 day
temperature outlook leans on the cooler side for the Midwest, Northeast, and
Mid-Atlantic. Positive 500-hPa height anomalies support an increased chance of
above-normal temperatures across the Rockies and High Plains. Model solutions
depict a shortwave trough reaching the West Coast by day 8, which would enhance
the onshore flow and bring a cooling trend (especially to California and the
Pacific Northwest).

The highest forecast confidence in the 6-10 day precipitation outlook is across
the Pacific Northwest, northern California, and Northern Intermountain West
where the shortwave trough along with enhanced onshore flow support relatively
large above-normal precipitation probabilities (greater than 60 percent). These
large probabilities are also related to a drier climatology at this time of
year. Downstream of this shortwave trough, above-normal precipitation is
favored for the Northern to Central Rockies, Great Plains, and parts of the
Mississippi Valley. As of 8am MST on September 2, the National Hurricane Center
forecasts Tropical Storm Elena in the East Pacific to turn north-northeast
towards the Baja Peninsula later this week. Enhanced low to mid-level moisture,
associated with the remnants of this tropical cyclone, may overspread the
south-central CONUS and interact with a stationary front located across
Oklahoma and Texas. Along a nearly stationary front and consistent with the
uncalibrated and reforecast tools, elevated above-normal precipitation
probabilities are forecast for the Southeast and Mid-Atlantic. Farther to the
north across parts of the Great Lakes along with northern New York and Maine,
below-normal precipitation is more likely.

The GEFS, ECENS, and CMCE depict positive 500-hPa height anomalies throughout
Alaska with near to above-normal temperatures favored statewide. Downstream of
a broad trough centered over the Bering Sea, elevated above-normal
precipitation probabilities are forecast for a majority of Alaska.

The official 6-10 day 500-hPa height blend consists of 30% of Today`s 6z GFS
Ensemble Mean centered on Day 8, 35% of Today`s 0z European Ensemble Mean
centered on Day 8, and 35% 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 a
transition to more zonal flow.

8-14 DAY OUTLOOK FOR SEP 10 - 16 2025

Multi-model ensemble means (GEFS, ECENS, and CMCE) are in good agreement with a
pair of 500-hPa troughs along the East Coast and just inland from the West
Coast. Due to the less amplified longwave pattern, 500-hPa height anomalies are
forecast to be small (within 30 meters averaged out during a 7-day period). The
manual 500-hPa height blend depicts the largest anomaly (+90 meters or more)
over Hudson Bay and north-central Canada, which typically corresponds to
warmer-than-normal temperatures for the central CONUS. The week-2 temperature
outlook calls for an increased chance of above-normal temperatures from the
Rockies to the Mississippi Valley and along the Gulf Coast. This is consistent
with the auto and consolidation tools along with the analog tool derived from
the manual 500-hPa height blend. A predicted cool start to week-2 tilts the
outlook towards below-normal temperatures across the Mid-Atlantic and
Northeast, but ensemble means agree that temperatures moderate by day 10 or 11.
Due to the trough just inland from the West Coast, near to below-normal
temperatures are favored for much of the western CONUS. However, many of the
temperature tools depict a tilt towards above-normal temperatures closer to
coastal areas of northern California and the Pacific Northwest, which could be
somewhat related to nearby sea surface temperature anomalies.

Similar to the 6-10 day period, the highest forecast confidence in the 8-14 day
precipitation outlook is across the northwest quarter of the CONUS. This region
is expected to be affected by the shortwave trough entering the West and
climatology remains low in mid-September. Elsewhere throughout the CONUS,
forecast confidence in the precipitation outlook is low due to the transition
to the more zonal flow pattern and also given the time of year. By day 8
(September 10), any enhanced precipitation associated with the remnants of the
East Pacific tropical cyclone should begin to time off. The consolidation tool
(skill-weighted GEFS and ECMWF reforecasts) generally favors near to
below-normal precipitation for the Northeast, Great Lakes, Ohio Valley, and
southern Great Plains. Westerly flow, associated with the trough entering the
West, would tend to suppress any late season monsoon precipitation across the
Desert Southwest.

As of 2pm EDT on September 2, the NHC is monitoring a tropical wave currently
over the eastern Atlantic and state that there is a 70 percent chance of
tropical cyclone (TC) development across the Main Development Region of the
Atlantic during the next week. The model consensus is for this potential TC to
remain offshore of the East Coast with a predicted break in the subtropical
ridge. However, this will have to be closely monitored in the days ahead.

Consistent with 500-hPa height anomalies and the reforecast tools, above-normal
temperatures are favored throughout Alaska. Precipitation tools depict only
weak signals, but the broad trough upstream over the Bering Sea tilts the
outlook towards the wetter side across southern Alaska.

Based on the GEFS and ECENS, above-normal temperatures and above-normal
precipitation are favored for Hawaii. Positive sea surface temperature
anomalies also support above-normal temperatures, especially across the
northwestern islands.

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
zonal flow and low confidence in the precipitation outlook for most of the
CONUS.

FORECASTER: Brad 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 (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:
19610819 - 19790821 - 19630828 - 19860904 - 19540831


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:
19610818 - 19790821 - 19860903 - 19630827 - 19510822


6-10 DAY OUTLOOK TABLE
Outlook for Sep 08 - 12 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       A    A     NEVADA      N    A
W MONTANA   A    A     E MONTANA   A    A     WYOMING     A    A
UTAH        A    A     ARIZONA     A    B     COLORADO    A    A
NEW MEXICO  A    N     N DAKOTA    A    A     S DAKOTA    A    A
NEBRASKA    A    A     KANSAS      B    A     OKLAHOMA    B    A
N TEXAS     B    A     S TEXAS     A    A     W TEXAS     A    A
MINNESOTA   B    A     IOWA        B    A     MISSOURI    B    N
ARKANSAS    B    N     LOUISIANA   A    A     WISCONSIN   B    N
ILLINOIS    B    N     MISSISSIPPI N    A     MICHIGAN    B    N
INDIANA     B    N     OHIO        B    N     KENTUCKY    B    N
TENNESSEE   B    A     ALABAMA     N    A     NEW YORK    B    N
VERMONT     B    N     NEW HAMP    B    N     MAINE       B    N
MASS        B    A     CONN        B    A     RHODE IS    B    A
PENN        B    N     NEW JERSEY  B    A     W VIRGINIA  B    A
MARYLAND    B    A     DELAWARE    B    A     VIRGINIA    B    A
N CAROLINA  B    A     S CAROLINA  B    A     GEORGIA     N    A
FL PNHDL    A    A     FL PENIN    A    A     AK N SLOPE  N    A
AK ALEUTIAN A    A     AK WESTERN  N    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 10 - 16 2025

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

$$