206
FXUS06 KWBC 291902
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 29 2025

6-10 DAY OUTLOOK FOR SEP 04 - 08 2025

Today`s numerical models depict an amplified 500-hPa flow pattern across North
America and surrounding areas early in the period followed by a rapid
de-amplification by day 10. The period begins with strong ridging over western
Canada and a deep anomalous trough over the eastern half of the CONUS. As time
progresses, the ridge over western Canada is forecast to retrograde toward the
Gulf of Alaska and reduce in magnitude. Meanwhile the trough in the East is
forecast to remain anomalously strong through days 7 and 8 and then rapidly
weaken and transition to a zonal pattern by day 10. The 5 day mean 500-hPa
blend features above normal heights across Alaska and the northwestern CONUS.
Below to much below normal heights are forecast across the Eastern Conus with
mean 500-hPa departures of -90 meters noted over the central Great Lakes,
mainly due to strong trough amplification early in the period. Ridging and near
to above normal 500-hPa heights are forecast for Hawaii.

The highly amplified trough forecast across the eastern CONUS, especially early
in the period, strongly favors below normal temperatures. Below normal
temperatures are favored for almost the entire eastern half of the country with
the exceptions of the Florida Peninsula, parts of the western Gulf Coast, and
eastern Maine. Probabilities of below normal temperatures exceed 80 percent
from the central Great Lakes southward to much of the Ohio and Middle
Mississippi valleys. Subtropical ridging to the south of a mean frontal
boundary favors above normal temperatures for most of the Florida Peninsula.
Above normal SSTs in the adjacent Atlantic and Gulf also enhance chances for
above normal temperatures across much of the Florida Peninsula. Broad anomalous
ridging over western Canada favors above normal temperatures across Alaska and
the Pacific Northwest. Modestly enhanced probabilities of above normal
temperatures extend southward across much of the remainder of the CONUS west of
the Rockies ahead of a weak trough forecast off the West Coast. Conversely,
below normal temperatures are more likely for the eastern portions of the
Southwest and most of the Rio Grande Valley, consistent with teleconnections
from the forecast positive height anomaly center associated with the ridge
forecast over western Canada. Increased cloudiness and moisture may also act to
keep maximum temperatures down for these areas. Above normal temperatures are
favored for Hawaii due to predicted ridging and above normal sea surface
temperatures in the adjacent Pacific, particularly across the western islands.

Above normal precipitation is favored for the Southwest, much of the Great
Basin, the southern and central Rockies, and the Southern Plains. Influxes of
monsoonal moisture across the Southwest combined with a stationary frontal
boundary across the southern High Plains are the main drivers for this
predicted active period. Probabilities of above normal precipitation exceed 50
percent across much of the Southwest. Above normal precipitation is also
favored for the Florida Peninsula due to a predicted frontal boundary at the
base of the anomalous trough forecast over the eastern CONUS. Precipitation
chances are also elevated across much of the northeastern quadrant of the CONUS
ahead of the predicted mean trough axis. Below normal precipitation is more
likely across the Northern Plains and adjacent areas of the Upper Mississippi
Valley due to predicted surface high pressure associated with a cool stable
Canadian airmass. Below normal precipitation is slightly favored for parts of
the interior Southeast and adjacent areas of the Lower Mississippi Valley as
stable high pressure pushes well to the south of what is typical this time of
year. Below normal precipitation is also favored for parts of southeast Alaska
and the Pacific Northwest, associated with anomalous ridging forecast over
western Canada. Above normal precipitation is more likely across most of the
remainder of Alaska ahead of a weak trough predicted over the Bering Sea. Near
normal precipitation is slightly favored for Hawaii, due to weak signals among
the forecast tools.

The official 6-10 day 500-hPa height blend consists of 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 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 SEP 06 - 12 2025

By week-2, a transitional 500-hPa pattern is well underway across much of the
country. The period starts off with residual ridging over the Gulf of Alaska
and anomalous troughing across much of the eastern CONUS.  As time progresses,
a much more zonal pattern takes hold across much of the CONUS. There is even
some evidence of a reversal of the pattern by the end of week-2 with strong
troughing over the East on day 8 being replaced by modest ridging by day 14.
Conversely, the predicted ridge over the Gulf of Alaska is expected to be a
more stable feature with above normal heights forecast across most of Alaska
throughout the period. In fact, the ECMWF and GEFS ensembles favor some ridge
amplification across Southeast Alaska toward the end of the period. A variable
pattern is forecast across the western CONUS as early ridging quickly
dissipates and is replaced by shallow cyclonic flow by the middle of the
period. Generally near normal heights are forecast for Hawaii throughout the
period.

Above normal temperatures are likely for most of Alaska due to persistent
ridging and above normal heights. Enhanced probabilities of above normal
temperatures extend southward across much of the western CONUS due to predicted
ridging early in the period. Conversely, below normal temperatures are favored
for most of the eastern CONUS and much of the southern Plains due to predicted
anomalous troughing early in the period. Above normal temperatures are more
likely for most of the Florida Peninsula to the south of a predicted frontal
boundary and consistent with above normal SSTs in the adjacent Atlantic and
Gulf. Above normal temperatures are likely for Hawaii, due largely to observed
above normal SSTs in the adjacent Pacific.

A wet pattern is favored for the interior West and adjacent Plains, due to a
combination of residual monsoonal moisture and a transition to a more zonal or
weakly cyclonic flow pattern toward the middle and end of the period. Above
normal precipitation chances are elevated along the Gulf and Southeast coasts
around the periphery of a predicted anomalous trough early in the period. A
slight tilt toward above normal precipitation is also indicated for most of
Maine and adjacent northern New Hampshire ahead of the predicted trough axis.
Modestly enhanced chances of below normal precipitation is forecast for much of
the Great Lakes and Ohio valley due to predicted surface high pressure early in
the period. These enhanced below normal precipitation chances were kept low due
to the potential transition to a wetter pattern toward the end of week-2. Above
normal precipitation is favored for most of Mainland Alaska and the Alaska
Peninsula ahead of weak troughing forecast over the Bering Sea. A dry pattern
is more likely across Southeast Alaska due to persistent ridging. Near normal
precipitation is favored across the Hawaiian islands, due to weak or
conflicting guidance.

The official 8-14 day 500-hPa height blend consists of: 30% 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
uncertainties surrounding a predicted transitional 500-hPa flow pattern across
much of North America.

FORECASTER: Scott H

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:
19630828 - 19660823 - 19510902 - 19810809 - 19880823


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:
19630827 - 19510903 - 19660822 - 19880822 - 19630822


6-10 DAY OUTLOOK TABLE
Outlook for Sep 04 - 08 2025

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



8-14 DAY OUTLOOK TABLE
Outlook for Sep 06 - 12 2025

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    N     OREGON      A    N     NRN CALIF   A    N
SRN CALIF   N    N     IDAHO       A    A     NEVADA      A    A
W MONTANA   A    A     E MONTANA   N    A     WYOMING     N    A
UTAH        N    A     ARIZONA     N    A     COLORADO    N    A
NEW MEXICO  N    A     N DAKOTA    N    N     S DAKOTA    N    A
NEBRASKA    N    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    N
ARKANSAS    B    N     LOUISIANA   N    A     WISCONSIN   B    B
ILLINOIS    B    B     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     N    N     NEW HAMP    N    N     MAINE       N    A
MASS        B    N     CONN        B    N     RHODE IS    B    N
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    A     GEORGIA     N    A
FL PNHDL    N    A     FL PENIN    A    A     AK N SLOPE  A    A
AK ALEUTIAN A    N     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.

$$