969
FXUS06 KWBC 092018
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EST Tue December 09 2025

6-10 DAY OUTLOOK FOR DEC 15 - 19 2025

The 0Z ECMWF, GEFS, and Canadian ensemble means predict an amplified
circulation pattern over North America for the 6-10 day period. All models
predict an amplified ridge and a strong positive 500-hPa height anomaly
centered to the west of Mainland Alaska. Downstream, models predict a
positively tilted trough and negative 500-hPa height anomalies over eastern
Mainland Alaska, Southeast Alaska and the Gulf of Alaska. Ensemble means
predict a ridge and associated positive 500-hPa height anomalies over the
western and central contiguous U.S. (CONUS) at the start of the 6-10 day period
that expands eastward over time. A trough and associated negative 500-hPa
height anomalies over the northeastern CONUS at the start of the period are
predicted to rapidly progress northeastward, as mid-level height heights rise.
A second trough is predicted to amplify and progress over the eastern CONUS
later in the period. The GEFS ensemble mean predicts greater negative 500-hPa
height anomalies related to the second trough than the ECMWF ensemble mean.

Above normal temperatures are favored for the western Aleutian Islands under
predicted positive 500-hPa height anomalies. Below normal temperatures are
likely for Mainland Alaska, under anomalous northerly mid-level flow. Below
normal temperatures are likely for Southeast Alaska, under a predicted trough.
Above normal temperatures are very likely for the western and south-central
CONUS, under a persistent ridge. Probabilities exceed 90 percent over parts of
the Great Basin and Central Rockies, supported by the consolidation of
calibrated GEFS and ECMWF temperature probability forecasts. Below normal
temperatures are likely over the northeastern CONUS stretching from the Midwest
to most of the Atlantic coast from Georgia to Maine, under northerly flow and
predicted troughing during the period. There is greater uncertainty over the
Southeast, where the GEFS forecast probabilities favor more extensive below
normal temperatures, while the ECMWF model favors above normal temperatures.
Above normal temperatures are favored for the southern Florida Peninsula,
consistent with the temperature consolidation. Above normal temperatures are
very likely across Hawaii in the 6-10 day period, consistent with the
temperature consolidation.

Below normal precipitation is likely for the Aleutian Islands and southwestern
Mainland Alaska, under and ahead of the positive 500-hPa anomaly center. Above
normal precipitation is slightly favored for a small area of the northeastern
coast of Mainland Alaska, consistent with all ensemble model precipitation
forecasts. Above normal precipitation is very likely for the Pacific Northwest
across the Northern Rockies, ahead of the trough over the North Pacific and
consistent with all ensemble model precipitation tools. Enhanced probabilities
for above normal precipitation extend as far south as the San Francisco Bay
Area, consistent with teleconnections to the strong positive 500-hPa height
anomaly center to the west of Alaska. Above normal precipitation is favored
across the northern tier into parts of the Northern Plains and much of the
Great Lakes region, under strong westerly mid-level flow. Below normal
precipitation is favored over the southwestern CONUS and the Central Plains,
under the predicted ridge and positive 500-hPa height anomalies. Below normal
precipitation is slightly favored over the Ohio and Tennessee Valleys and parts
of the central Appalachians, consistent with most model precipitation tools,
despite uncertainty in a changing pattern. Probabilities for above normal
precipitation are enhanced over southeastern areas of Texas, Louisiana, and the
Florida Peninsula, where model forecasts are in agreement. Above normal
precipitation is favored for most of the Hawaiian Islands, excluding the Big
Island, consistent with model forecasts.

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
overall agreement among ensemble means on the amplified 500-hPa height pattern,
offset by differences among temperature and precipitation tools for some areas
related to a changing pattern.

8-14 DAY OUTLOOK FOR DEC 17 - 23 2025

The 500-hPa height pattern persists somewhat into the 8-14 day period in 0Z
ECMWF, GEFS and Canadian ensemble mean forecasts. A very amplified ridge and
positive 500-hPa height anomaly persists to the west of Mainland Alaska. A
trough and associated negative 500-hPa height anomalies are predicted
downstream over eastern Mainland Alaska and Southeast Alaska. Positive 500-hPa
height anomalies expand across the entire CONUS in the manual blend and the 0Z
ECMWF and Canadian ensemble means, while a trough persists over the Northeast
and Atlantic Coast in the 0Z GEFS ensemble mean forecast.

Above normal temperatures continue to be favored for the western Aleutian
Islands in the 8-14 day period, under strong positive 500-hPa height anomalies.
Below normal temperatures are likely across the Alaska Mainland in the week-2
period, under anomalous northerly mid-level flow. Model tools for the CONUS
predict likely above normal temperatures across the western CONUS, under a
persistent ridge and positive 500-hPa height anomalies. Enhanced probabilities
for above normal temperatures expand eastward across the Middle and Lower
Mississippi Valley and most of the Southeast in the 8-14 day period, as
mid-level heights are predicted to rise. However, continued disagreement in the
GEFS and ECMWF temperature forecast tools leads to only moderate forecast
probabilities in the Southeast and favored near normal temperatures for the
Ohio Valley and central Atlantic Coast. Below normal temperatures are favored
for the northern Great Lakes and Northeast regions, under predicted anomalous
northerly flow through most of the 8-14 day period. The consolidation continues
to support high probabilities for above normal temperatures for Hawaii.

Below normal precipitation is favored for southwestern Mainland Alaska in the
week-2 period, under anomalous northerly flow ahead of the amplified ridge.
Ahead of the trough over the North Pacific, above normal precipitation
continues to be likely for the Pacific Northwest, with probabilities exceeding
50 percent for most of the region. Enhanced probabilities for above normal
precipitation extend from the San Francisco Bay Area across Northern California
and northern Nevada, consistent with teleconnections to the positive 500-hPa
height anomaly center to the west of Alaska. Enhanced probabilities for above
normal precipitation extend across parts of the Northern Plains into northern
areas of the Great Lakes and Northeast regions, consistent with the
precipitation consolidation. Below normal precipitation is favored for the
Southwest, the Central Plains, the Central Mississippi Valley, and the central
Appalachians, under the predicted ridge. Above normal precipitation continues
to be favored for South Texas and the southern Florida Peninsula, consistent
with most tools. The precipitation consolidation supports slightly enhanced
probabilities of above normal precipitation for the northwestern Hawaiian
Islands, while below normal precipitation is favored for the Big Island.

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: About average, 3 out of 5, due to
overall agreement on the evolving mid-level circulation pattern, with
differences in temperature and precipitation forecast tools for some areas.

FORECASTER: D Collins

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 (gray, "N") normal.
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 (gray, "N")
normal. 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
December 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:
20131213 - 19951129 - 20081208 - 19911204 - 19891122


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:
20131213 - 20081207 - 19911204 - 19951128 - 20131218


6-10 DAY OUTLOOK TABLE
Outlook for Dec 15 - 19 2025

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



8-14 DAY OUTLOOK TABLE
Outlook for Dec 17 - 23 2025

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

$$