806
FXUS06 KWBC 201902
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Wed August 20 2025

6-10 DAY OUTLOOK FOR AUG 26 - 30 2025

Today`s ensemble mean solutions generally depict a high amplitude 500-hPa
pattern across much of North America and surrounding areas. The most dominant
features include a strong ridge centered over 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 over the eastern Pacific
as a pair of negative height anomaly centers are predicted. The first 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 Grande Valley to
the western Gulf Coast region.

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 northeastern 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, below-normal temperatures
are slightly favored across interior 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 with enhanced monsoon moisture
forecast in the region during the period. Stronger chances of below-normal
temperatures are likely from most of the Eastern Seaboard westward to much of
the Plains due to anomalous troughing centered over the 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 and the Rio Grande Valley due to predicted subtropical ridging.
Increased probabilities of above-normal temperatures are indicated for Hawaii
(with the greatest confidence over western and central portions of the state)
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 Central and 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. Near-normal
precipitation is favored for the Northeast as most frontal boundaries
associated with the mid-level trough will have progressed through the region.
Above-normal precipitation is slightly favored along the Southeast Atlantic
Coast associated with a frontal boundary. Below-normal precipitation is likely
for Southeast Alaska 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. Near-normal precipitation is more likely for most of
Hawaii, with the exception of the Big Island. A slight tilt toward below-normal
precipitation is forecast for most of the Big Island, associated with predicted
anomalous ridging centered to the east of the island chain.

The official 6-10 day 500-hPa height blend consists of 10% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 30% of Today`s 6z GFS Ensemble Mean centered
on Day 8, 40% of Today`s 0z European Ensemble Mean centered on Day 8, and 20%
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 28 - SEP 03, 2025

Similarly to yesterday, 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
further 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 southern and central Alaska and the northwestern CONUS. Above-normal
temperature probabilities exceed 50 percent for Washington State and adjacent
areas of northern Oregon and the Northern Rockies. Below-normal temperatures
are most likely for northern Mainland Alaska. 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 parts of the Central and Southern
Appalachians. Above-normal temperatures are more likely to the south of this
trough, for the Florida Peninsula, most of the Gulf Coast, the southern half of
Texas, and southeastern portions of the Southwest, 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 analog guidance based on the 500-hPa height pattern. Model guidance is
bringing enhanced chances of above-normal precipitation to much of the Pacific
Northwest coastal areas in addition to interior portions of the region.
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 Northeast as surface high
pressure associated with a Canadian airmass settles in. Above-normal
precipitation is favored along the southern half of the immediate East Coast
ahead of the mean trough predicted over the eastern Great Lakes. Ridging leads
to increased chances of below-normal precipitation across Southeast Alaska,
however these chances are reduced relative to yesterday as the ridge centers
shifts east. An active pattern is more likely for much of the remainder of the
state ahead of a trough forecast near the Chukchi Peninsula. Near-normal
precipitation is favored for Hawaii consistent with the blend of model tools.

The official 8-14 day 500-hPa height blend consists of: 35% of Today`s 6z 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 on the 500-hPa pattern early in the period, offset by increased
uncertainty and decreased pattern amplification later in week-2.


FORECASTER: Ryan Bolt

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 - 19830802 - 19600902 - 19950818


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:
19910829 - 20010804 - 19950820 - 19690821 - 19830801


6-10 DAY OUTLOOK TABLE
Outlook for Aug 26 - 30 2025

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    A     OREGON      A    A     NRN CALIF   A    A
SRN CALIF   N    A     IDAHO       A    A     NEVADA      N    A
W MONTANA   A    A     E MONTANA   A    B     WYOMING     B    A
UTAH        B    A     ARIZONA     B    A     COLORADO    B    A
NEW MEXICO  B    A     N DAKOTA    B    B     S DAKOTA    B    N
NEBRASKA    B    A     KANSAS      B    A     OKLAHOMA    B    A
N TEXAS     B    A     S TEXAS     A    A     W TEXAS     B    A
MINNESOTA   B    B     IOWA        B    B     MISSOURI    B    A
ARKANSAS    B    A     LOUISIANA   N    A     WISCONSIN   B    B
ILLINOIS    B    B     MISSISSIPPI B    A     MICHIGAN    B    B
INDIANA     B    B     OHIO        B    B     KENTUCKY    B    B
TENNESSEE   B    N     ALABAMA     B    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        B    B     NEW JERSEY  B    N     W VIRGINIA  B    B
MARYLAND    B    B     DELAWARE    B    N     VIRGINIA    B    B
N CAROLINA  B    N     S CAROLINA  B    N     GEORGIA     B    N
FL PNHDL    B    N     FL PENIN    A    N     AK N SLOPE  B    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 Aug 28 - Sep 03, 2025

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

$$