460
FXUS06 KWBC 041902
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 04 2025

6-10 DAY OUTLOOK FOR SEP 10 - 14 2025

The GEFS, ECENS, and CMCE are in good agreement that the mid-level pattern
becomes zonal with prevailing westerly flow by mid-September. This pattern
transition is likely to bring a warming trend to the central and then eastern
contiguous U.S. (CONUS) after a prolonged stretch of below-normal temperatures.
A flip from below to above-normal temperatures is forecast to begin as early as
day 6 (September 10) across the Northern to Central Great Plains. The
above-normal temperatures are then expected to expand east of the Mississippi
River to the Appalachians by day 10 (September 14). During this 5-day period,
above-normal temperature probabilities are largest (60 percent or more)
throughout the north-central CONUS where the pattern change occurs sooner.
Since multi-model ensemble mean solutions depict cooler-than-normal
temperatures persisting through day 8 or 9 to the east of the Appalachians,
below-normal temperatures are favored for much of the eastern CONUS.

An amplified shortwave trough with enhanced onshore flow supports an increased
chance of above-normal precipitation across the Pacific Northwest, northern
California, and the Northern Intermountain West. These large probabilities are
also related to a drier climatology at this time of year. This shortwave trough
leads to elevated below-normal temperature probabilities for interior portions
of the West. Downstream of this shortwave trough, above-normal precipitation is
favored for the Rockies along with the Northern to Central Great Plains. Model
guidance continues to trend towards a drier solution for most of the eastern
and south-central CONUS as surface high pressure, centered over southeastern
Canada, becomes more dominant and a surface trough is shifting away from the
East Coast. Below-normal precipitation probabilities now exceed 50 percent
throughout most of the Ohio and Tennessee Valleys, and adjacent areas of the
Lower and Middle Mississippi Valleys. A break in the subtropical ridge is
likely to promote enhanced convection and favors above-normal precipitation for
the coastal Southeast and Florida Peninsula.

The GEFS, ECENS, and CMCE depict a 500-hPa trough over western Alaska and tools
have trended colder across western and northern parts of the state. Based on
the consolidation (skill-weighted GEFS and ECENS reforecasts), an increased
chance of below-normal temperatures is forecast for northwestern Alaska. To the
west of the trough axis, below-normal precipitation is favored for western
Alaska. Southwesterly surface flow favors above-normal temperatures and
precipitation across southeastern Alaska. The increased chance of above-normal
precipitation extends north to include all of eastern Mainland Alaska.

As of 5am HST on September 4, Hurricane Kiko in the Central Pacific is forecast
to track closer to the Hawaiian Islands early next week. Either Kiko or its
remnant low increases the chance of above-normal precipitation throughout
Hawaii. Based on the GEFS and ECENS, above-normal temperatures are favored for
Hawaii.

The official 6-10 day 500-hPa height blend consists of 35% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 35% 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 model agreement and continuity on the upcoming pattern change and improved
agreement among the precipitation tools.

8-14 DAY OUTLOOK FOR SEP 12 - 18 2025

Multi-model ensemble means (GEFS, ECENS, and CMCE) are in good agreement that
the 500-hPa troughs over the West and coastal Southeast weaken beyond the early
part of week-2. These ensemble means continue to feature a large-scale ridge
over central Canada with a corresponding positive 500-hPa height anomaly center
at Hudson Bay. A teleconnection upon this prominent height anomaly was used as
guidance in the week-2 temperature and precipitation outlooks. Consistent with
the positive 500-hPa height anomalies across the northern tier of the CONUS and
westerly mid-level flow, above-normal temperatures are favored for a majority
of the lower 48 states. This predicted switch from below to above-normal
temperatures across the Midwest would be a significant pattern change following
the extended period of below-normal temperatures from late August through early
September. The anomalous warmth, initially over the north-central CONUS, is
expected to overspread the East later in week-2. Therefore, near to
above-normal temperatures are favored across most of the eastern third of the
CONUS. However, a relatively cool start to week-2 and persistent easterly
surface flow tilt the outlook towards below-normal temperature along the
coastal Mid-Atlantic.

Along and downstream of the 500-hPa trough predicted to be over the West early
in week-2, above-normal precipitation is favored from the Pacific Northwest and
northern California east to the Northern to Central Great Plains. A large-scale
surface high, with its axis oriented from the Northeast southwestward to the
Lower Mississippi Valley, favors a widespread area of below-normal
precipitation generally between the Mississippi River and Appalachians as well
as across much of the Southern Plains.

A mid-level trough and break in the subtropical ridge continues to elevate the
chance of above-normal precipitation across the Florida Peninsula. As of 2pm
EDT on September 4, the National Hurricane Center is monitoring a tropical wave
currently over the eastern Atlantic and state that there is a 90 percent chance
of tropical cyclone (TC) development across the Main Development Region of the
Atlantic during the next week. Its future modeled track will be closely
monitored in the days ahead.

The ensemble means all depict a broad trough centered over Mainland Alaska.
This trough tilts the outlook towards the colder side across much of
northwestern Alaska, while southwesterly flow early in week-2 favors
above-normal temperatures for southeastern Alaska. The GEFS and ECENS
reforecast tools are in good agreement with an elevated chance of below
(above)-normal precipitation across western (southeastern) 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: 35% of Today`s 0z GFS
Ensemble Mean centered on Day 11, 35% 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: Average, 3 out of 5, due to good
model agreement and continuity on the temperature outlook offset by a
transition to zonal flow and uncertainty with the future track of a potential
tropical cyclone emerging from the Main Development Region of the Atlantic.

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:
19790822 - 19610819 - 19860904 - 19940818 - 19710918


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:
19790822 - 19890910 - 19860904 - 19610819 - 19820917


6-10 DAY OUTLOOK TABLE
Outlook for Sep 10 - 14 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       N    A     NEVADA      B    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    A    A     S DAKOTA    A    A
NEBRASKA    A    A     KANSAS      A    A     OKLAHOMA    A    B
N TEXAS     A    B     S TEXAS     A    B     W TEXAS     A    B
MINNESOTA   A    A     IOWA        A    N     MISSOURI    A    B
ARKANSAS    A    B     LOUISIANA   A    B     WISCONSIN   A    N
ILLINOIS    A    B     MISSISSIPPI A    B     MICHIGAN    N    B
INDIANA     A    B     OHIO        N    B     KENTUCKY    N    B
TENNESSEE   N    B     ALABAMA     N    B     NEW YORK    B    B
VERMONT     B    B     NEW HAMP    B    B     MAINE       B    B
MASS        B    B     CONN        B    B     RHODE IS    B    B
PENN        B    B     NEW JERSEY  B    B     W VIRGINIA  B    B
MARYLAND    B    B     DELAWARE    B    B     VIRGINIA    B    B
N CAROLINA  B    B     S CAROLINA  B    B     GEORGIA     B    B
FL PNHDL    B    A     FL PENIN    B    A     AK N SLOPE  B    A
AK ALEUTIAN N    N     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 12 - 18 2025

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

$$