685
FXUS06 KWBC 191951
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Tue August 19 2025

6-10 DAY OUTLOOK FOR AUG 25 - 29 2025

Today`s ensemble mean solutions generally depict a high amplitude pattern
across much of North America and surrounding areas. The most dominant features
include a strong ridge centered just off the coast of Southeast Alaska, a
strong mid-level low to its north over the Arctic Ocean, and a broad anomalous
trough over the eastern CONUS. A complex pattern is forecast upstream over the
Pacific as a trough is predicted well south of the Gulf of Alaska, undercutting
the ridge to its north. A second, weaker trough is predicted further to the
south, just off the West Coast of the CONUS. Downstream of North America,
anomalous ridging is predicted over the North Atlantic extending northward to
just off the coast of Atlantic Canada. Farther to the south, subtropical
ridging is forecast along much of the southern tier of the CONUS, centered from
the Rio Grand Valley to the western Gulf Coast region. The ECMWF ensemble mean
depicts a weakness in this subtropical ridge over the Southeast.

A strong ridge forecast near southeastern Alaska favors above-normal
temperatures for the southern and central Mainland, Southeast Alaska, and
southward to the northwestern CONUS. Probabilities of above-normal temperatures
exceed 80 percent for much of Washington State. Below-normal temperatures are
favored for the Alaska North Slope near a predicted anomalous mid-level low
over the adjacent Arctic Ocean. Farther to the south, near-normal temperatures
are more likely across much of southern California into the Southwest and Great
Basin associated with weak troughing forecast just off the coast and due to the
potential for increased cloudiness. Below-normal temperatures are likely from
most of the Eastern Seaboard westward to much of the Plains due to anomalous
troughing centered over the eastern Great Lakes. Chances of below-normal
temperatures exceed 80 percent for the Ohio Valley, southern Great Lakes,
Middle Mississippi Valley, and adjacent areas of the central Plains.
Above-normal temperatures are more likely farther to the south, for the Florida
Peninsula, southern portions of the Southern Plains, the Rio Grand Valley, and
southeastern parts of the Southwest due to predicted subtropical ridging.
Increased probabilities of above-normal temperatures are indicated for western
and central portions of Hawaii driven mostly by observed positive sea surface
temperatures anomalies in the adjacent Pacific.

Above-normal precipitation is favored for a broad area of the Interior West
ahead of a trough predicted off the West Coast and associated with potential
influxes of Monsoonal moisture. Increased chances of above-normal precipitation
extends eastward to much of the southern Plains, associated with a predicted
stationary frontal boundary. Below-normal precipitation is more likely across
the Upper Mississippi Valley, the western Great Lakes, much of the Ohio Valley,
and parts of the Northern Plains associated with a predicted surface high
pressure and associated stable Canadian airmass. Above-normal precipitation is
slightly favored along the East Coast, ahead of a predicted trough centered
over the eastern Great Lakes. Below-normal precipitation is likely from
southeastern Alaska to the Pacific Northwest due to predicted expansive
ridging. An active pattern is more likely for the remainder of Alaska ahead of
a mean trough predicted near the Chukchi Peninsula. Below-normal precipitation
is more likely for parts of the Big Island of Hawaii associated with predicted
anomalous ridging centered to the east of the island chain.

The official 6-10 day 500-hPa height blend consists of 20% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 50% 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 agreement among todays ensemble means.

8-14 DAY OUTLOOK FOR AUG 27 - SEP 02, 2025

The week-2 period features a marked reduction in amplitude of most of the main
features described in the 6-10 day discussion. However there is little change
in the location of these features between the two outlook periods. An anomalous
ridge is forecast to weaken and push slightly inland near Southeast Alaska and
extend southward to the Pacific Northwest and Northern Rockies. A mid-level low
to the north of Alaska is forecast to significantly weaken. Farther to the
south, persistent but shallow troughing is predicted off the West Coast of the
CONUS. A trough is forecast to persist over the eastern Great Lakes well into
week-2 but slowly weaken. Subtropical ridging of typical strength for this time
of year is forecast across much of the southern tier of the CONUS. Generally
near to above-normal 500-hPa heights are forecast for Hawaii due to predicted
anomalous ridging to the east of the state early in the period followed by the
potential development of another ridge northwest of the state later in week-2.

Persistent ridging over western Canada favors above-normal temperatures across
much of nearby Alaska and the northwestern CONUS. Above-normal temperature
probabilities exceed 60 percent for Washington State and adjacent areas of
northern Oregon. Below-normal temperatures are more likely across much of the
central and eastern CONUS due to a predicted anomalous trough centered near the
Great Lakes. Probabilities of below-normal temperatures exceed 60 percent for
much of the Ohio and Middle Mississippi valleys and adjacent central Plains.
Above-normal temperatures are more likely to the south of this trough, for the
Florida Peninsula and southern Texas, associated with subtropical ridging.
Above-normal temperatures are favored for Hawaii due mostly to positive SST
anomalies in the adjacent Pacific Ocean.

A wet pattern continues to be likely for much of the interior West, consistent
with teleconnections from an upstream ridge centered over western Canada.
Precipitation amounts across the parts of the Southwest and Great Basin may be
enhanced due to the advection of monsoonal moisture into the region. The area
of increased above-normal precipitation chances extends to parts of the
southern and central Plains due to the potential of a mean frontal boundary in
the vicinity. Drier than normal conditions are more likely well to the north
and west of this boundary, across the Great Lakes and Ohio Valley as surface
high pressure associated with a Canadian airmass settles in. Above-normal
precipitation is favored along the immediate East Coast ahead of the mean
trough predicted over the eastern Great Lakes. Strong ridging leads to
increased chances of below-normal precipitation across Southeast Alaska. An
active pattern is more likely for most of the remainder of the state ahead of a
trough forecast near the Chukchi Peninsula. A slight tilt toward below-normal
precipitation is forecast for the Big Island of Hawaii due to predicted
anomalous ridging to the east of the state early in the period. Near-normal
precipitation is favored for the remainder of the island chain farther away
from the ridge center.

The official 8-14 day 500-hPa height blend consists of: 25% of Today`s 6z GFS
Ensemble Mean centered on Day 11, 50% 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 on the 500-hPa pattern early in the period, offset by increased
uncertainty and decreased pattern amplification later in week-2.


FORECASTER: Scott H

Notes:


Automated forecasts are issued on Saturday and Sunday. Occasionally manual
intervention is necessary to address quality control and consistency issues. In
these cases, forecasts are manually drawn but a full discussion is not issued.


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
August 21.


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:
19910828 - 20010804 - 20010822 - 19600902 - 19950816


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:
19910828 - 19600901 - 19950818 - 19690821 - 19990815


6-10 DAY OUTLOOK TABLE
Outlook for Aug 25 - 29 2025

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    B     OREGON      A    A     NRN CALIF   A    N
SRN CALIF   N    A     IDAHO       A    A     NEVADA      A    A
W MONTANA   A    N     E MONTANA   N    N     WYOMING     N    A
UTAH        N    A     ARIZONA     N    A     COLORADO    B    A
NEW MEXICO  N    A     N DAKOTA    B    B     S DAKOTA    B    N
NEBRASKA    B    N     KANSAS      B    N     OKLAHOMA    B    A
N TEXAS     B    A     S TEXAS     A    A     W TEXAS     A    A
MINNESOTA   B    B     IOWA        B    B     MISSOURI    B    N
ARKANSAS    B    N     LOUISIANA   N    N     WISCONSIN   B    B
ILLINOIS    B    B     MISSISSIPPI B    N     MICHIGAN    B    B
INDIANA     B    B     OHIO        B    B     KENTUCKY    B    N
TENNESSEE   B    N     ALABAMA     B    N     NEW YORK    B    A
VERMONT     B    A     NEW HAMP    B    A     MAINE       B    A
MASS        B    A     CONN        B    A     RHODE IS    B    A
PENN        B    N     NEW JERSEY  B    A     W VIRGINIA  B    N
MARYLAND    B    N     DELAWARE    B    A     VIRGINIA    B    N
N CAROLINA  B    A     S CAROLINA  B    A     GEORGIA     B    N
FL PNHDL    N    N     FL PENIN    A    A     AK N SLOPE  B    A
AK ALEUTIAN A    A     AK WESTERN  A    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 Aug 27 - Sep 02, 2025

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

                           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.

$$