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FXUS06 KWBC 221901
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Fri August 22 2025

6-10 DAY OUTLOOK FOR AUG 28 - SEP 01, 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 northwestern Canada and a pair of
broad anomalous troughs over the eastern Contiguous U.S (CONUS) and the Bering
Sea. A complex pattern is forecast over the eastern Pacific into the
southwestern CONUS 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 southeast,
along 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 over northwestern Canada favors above-normal
temperatures for southern and central Mainland Alaska, Southeast Alaska, and
southward to the northwestern CONUS. Near-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 60 percent for the Ohio Valley, Mid-Atlantic,
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 and South Texas 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
extend 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 Great Lakes, Mid-Atlantic and
into the Northeast associated with predicted surface high pressure and
associated stable Canadian airmass. Above-normal precipitation is slightly
favored along the Southeast Atlantic Coast associated with a frontal boundary.
Near to below-normal precipitation is favored for Southeast Alaska due to
predicted positive 500-hPa height anomalies over the region. An active pattern
is more likely for the remainder of Alaska ahead of a mean trough predicted
over the Bering Sea. Near-normal precipitation is more likely for most 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 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: Average, 3 out of 5, due to good
agreement among todays ensemble means, offset by increasing uncertainty among
the model guidance.

8-14 DAY OUTLOOK FOR AUG 30 - SEP 05, 2025

There is increasing uncertainty in the evolution of the 500-hPa height pattern
during week-2. The GEFS mean has diverged from the ECENS and CMCE means.
Whereas the GEFS has a low amplitude forecast across much of the domain, the
ECENS and CMCE forecast stronger mid-level ridging over northwestern North
America for longer into the week-2 period. Further, the GEFS favors a stronger
mid-level trough undercutting the ridge and progressing into the northwestern
CONUS. The trough forecast across the eastern CONUS in the 6-10 day period
weakens by the middle of week-2 in all three of the main ensemble means.
Therefore, zonal flow is favored across much of the CONUS during the period. In
Alaska, if stronger mid-level ridging remains in place over western North
America, as forecast by the ECENS and CMCE, there could be a fairly amplified
trough across the Bering Sea into western Alaska, otherwise, the GEFS favored a
broader low-amplitude trough centered over the North Pacific. Positive
mid-level height anomalies are forecast for Hawaii throughout the period.

Persistent ridging over western Canada favors above-normal temperatures across
much of Alaska during week-2. Across the CONUS, a slight tilt towards
below-normal temperatures is favored. There is a high degree of uncertainty in
how long the colder than normal conditions will last across the CONUS. The GEFS
based tools indicate that cooler than normal conditions are likely to persist
across the southeastern CONUS longer than across the Plains. The ECENS based
guidance, in contrast, would bring above-normal temperatures into the Ohio
Valley during the period and maintain cooler than normal conditions across the
Plains and Rocky Mountains during the period. Therefore, low chances of
below-normal temperatures are the preferred forecast today. Above-normal
temperatures are favored along the northern, western, and southern boundaries
of the CONUS with mid-level ridging near each of those regions. Above-normal
temperatures are favored for Hawaii due mostly to positive SST anomalies in the
adjacent Pacific Ocean.

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. Enhanced monsoon precipitation chances are forecast to be lower by
the week-2 period. As such near- to slightly above-normal precipitation is
favored across the southwestern CONUS. In the southeastern CONUS, zonal flow
may lead to a more summer-like convective pattern across the region. Near to
below-normal conditions are more likely for the Great Lakes and Northeast as
surface high pressure associated with a Canadian airmass remains in place. As
mid-level ridging progresses inland, an increase in moisture is possible across
parts of Southeast Alaska, with near-normal precipitation favored in this area
today. An active pattern is more likely for much of the remainder of the state
ahead of a trough forecast over the Bering Sea. Drier conditions are becoming
favored in some tools across northwestern Alaska but some guidance remains
wetter, supporting a forecast of near-normal precipitation across this region.
Above-normal precipitation is favored for much of Hawaii consistent with the
blend of model tools, excluding portions of the Big Island where near-normal is
favored.

The official 8-14 day 500-hPa height blend consists of: 10% of Today`s 0z GFS
Ensemble Mean centered on Day 11, 20% 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
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
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:
19950820 - 19530820 - 20010806 - 19970903 - 19980802


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:
19950820 - 19980802 - 19530819 - 20060831 - 20010805


6-10 DAY OUTLOOK TABLE
Outlook for Aug 28 - Sep 01, 2025

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    A     OREGON      A    A     NRN CALIF   A    N
SRN CALIF   N    N     IDAHO       A    A     NEVADA      N    A
W MONTANA   A    A     E MONTANA   A    A     WYOMING     N    A
UTAH        B    A     ARIZONA     N    A     COLORADO    B    A
NEW MEXICO  N    A     N DAKOTA    A    N     S DAKOTA    B    A
NEBRASKA    B    A     KANSAS      B    A     OKLAHOMA    B    A
N TEXAS     B    A     S TEXAS     N    A     W TEXAS     B    A
MINNESOTA   N    N     IOWA        B    N     MISSOURI    B    A
ARKANSAS    B    A     LOUISIANA   B    A     WISCONSIN   B    B
ILLINOIS    B    N     MISSISSIPPI B    A     MICHIGAN    B    B
INDIANA     B    B     OHIO        B    B     KENTUCKY    B    N
TENNESSEE   B    A     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    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    A     GEORGIA     B    A
FL PNHDL    N    A     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



8-14 DAY OUTLOOK TABLE
Outlook for Aug 30 - Sep 05, 2025

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

$$