751
FXUS06 KWBC 181911
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Mon August 18 2025

6-10 DAY OUTLOOK FOR AUG 24 - 28 2025

The ECMWF, GEFS and Canadian ensemble models broadly agree on the 500-hPa
height pattern over North America and surrounding regions during the 6-10 day
period, with only minor variations among the models in terms of amplitude and
phase of predicted wave features. The manual height blend is based on 0Z
ensemble means, weighing the ECMWF model greater due to recent model anomaly
correlation skill. The manual blend shows a strong ridge and above normal
500-hPa heights from the Aleutians to southern and central Mainland Alaska and
below normal 500-hPa heights over northern Mainland Alaska. A trough is
forecast over northeast Pacific. A mid-level ridge and above normal 500-hPa
heights are forecast over the northwestern Contiguous U.S. (CONUS), while a
deep trough with below normal 500-hPa heights are predicted over the eastern
CONUS. Slightly above normal 500-hPa heights are predicted across Hawaii.

Below normal temperatures are favored for parts of northern Mainland Alaska due
to predicted below normal 500-hPa heights over the area, while above normal
temperatures are favored over central and southern Mainland Alaska, the
Aleutians, and the Alaska Panhandle, under a predicted ridge and above normal
500-hPa heights. Above normal temperature chances are elevated over the most of
the western CONUS and portions of the southern CONUS, which is attributed to
mid-level ridging and/or low-level southerly flow. Below normal temperatures
are favored over all but southernmost portions of the Central and Eastern
CONUS, associated with a predicted deep mid-level trough and below normal
500-hPa height. Above normal temperatures are likely for Hawaii associated with
above normal SSTs and 500-hPa heights, consistent with the automated and
consolidated temperature forecast tools.

Above normal precipitation is anticipated across much of Alaska due to enhanced
onshore flow and good model agreement. Strong ridging favors below normal
precipitation across the Aleutians, far southern Mainland Alaska, and Southeast
Alaska. Near to above normal precipitation is forecast over most of the western
CONUS (except for northwestern Washington, where below normal precipitation is
likely under 500-hPa ridging) and central CONUS, consistent with the automated
and consolidated precipitation forecast tools. Above normal precipitation is
forecast over the Atlantic Coast, ahead of a predicted trough, while below
normal precipitation is favored across parts of the Great Lakes, the Ohio and
Tennessee Valley, supported by Auto precipitation forecast tool. Below normal
precipitation is favored for Hawaii, associated with predicted above normal
500-hPa heights across the state, supported by the consolidation precipitation
forecast tool.

The official 6-10 day 500-hPa height blend consists of 30% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 40% 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 between ensemble models on the mid-level height pattern forecast.

8-14 DAY OUTLOOK FOR AUG 26 - SEP 01, 2025

Ensemble mean forecasts for the 500-hPa circulation pattern over North America
remain in general agreement during the 8-14 day period. In the manual blend of
model forecasts,a ridge and above normal 500-hPa heights are forecast to
persist across most of central and southern Alaska extending southeastward to
the northwestern CONUS, while below normal 500-hPa heights are forecast over
far northern Mainland Alaska. The deep anomalous trough is forecast over the
eastern CONUS  in the week-2 period, but expected to weaken compared with the
6-10 day period. Slightly above normal 500-hPa heights are predicted across
Hawaii.

Near to below normal temperature chances are elevated for northern Mainland
Alaska, due to  below normal 500-hPa heights, while above normal temperatures
are likely over southern Alaska, under a predicted ridge and above normal
500-hPa heights. Above normal temperatures are favored over much of the
south-central and southeastern CONUS during week-2, based on mid-level ridging,
positive 500-hPa height departures, and southerly flow from the Gulf, while
below normal temperatures are favored over parts of southern California,
southern Nevada, and western Arizona, supported by most of the dynamical
temperature forecast tools. Below normal temperatures are favored over all but
southern portions of the Central and Eastern  CONUS associated with a predicted
trough and below normal 500-hPa heights over the region. Based on the GEFS and
ECENS, above-normal temperatures are favored for Hawaii.

Below normal precipitation is forecast over Southeast Alaska and near to above
normal precipitation is likely over the remainder of Mainland Alaska and the
Aleutians, supported by most of the dynamical precipitation forecast tools.
Above normal precipitation is predicted over western and central CONUS, while
below normal precipitation is forecast over parts of southeastern Texas and
southern Louisiana, consistent with the consolidated and automated
precipitation forecast tools. Above normal is also forecast over the Atlantic
Coast ahead of a predicted trough. Below normal precipitation remains favored
for most of Hawaii, warranted by the  GEFS and ECENS consolidation
precipitation tool.

The official 8-14 day 500-hPa height blend consists of: 30% of Today`s 0z 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: Near average, 3 out of 5, due to
good overall agreement on the mid-level height forecast, offset by a
deamplifying pattern and weak signals in the precipitation tools.


FORECASTER: Luke 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:
19990815 - 19910828 - 20010822 - 19620808 - 20060807


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 - 19990815 - 19620808 - 19950817 - 20010821


6-10 DAY OUTLOOK TABLE
Outlook for Aug 24 - 28 2025

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    N     OREGON      A    A     NRN CALIF   A    A
SRN CALIF   A    A     IDAHO       A    A     NEVADA      A    A
W MONTANA   A    A     E MONTANA   A    A     WYOMING     A    A
UTAH        A    A     ARIZONA     A    A     COLORADO    B    A
NEW MEXICO  A    A     N DAKOTA    B    N     S DAKOTA    B    A
NEBRASKA    B    A     KANSAS      B    A     OKLAHOMA    B    A
N TEXAS     A    N     S TEXAS     A    N     W TEXAS     A    A
MINNESOTA   B    N     IOWA        B    N     MISSOURI    B    A
ARKANSAS    B    N     LOUISIANA   A    N     WISCONSIN   B    N
ILLINOIS    B    B     MISSISSIPPI B    N     MICHIGAN    B    N
INDIANA     B    B     OHIO        B    B     KENTUCKY    B    B
TENNESSEE   B    B     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    A     DELAWARE    B    A     VIRGINIA    B    A
N CAROLINA  B    A     S CAROLINA  B    A     GEORGIA     B    N
FL PNHDL    A    A     FL PENIN    A    A     AK N SLOPE  B    A
AK ALEUTIAN A    N     AK WESTERN  A    A     AK INT BSN  A    A
AK S INT    A    A     AK SO COAST A    B     AK PNHDL    A    B



8-14 DAY OUTLOOK TABLE
Outlook for Aug 26 - Sep 01, 2025

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

                           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.

$$