308
FXUS06 KWBC 092010
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EST Thu January 09 2025

6-10 DAY OUTLOOK FOR JAN 15 - 19 2025

There is good overall agreement between the latest ECMWF, GEFS, and Canadian
ensemble mean 500-hPa height forecasts on the predicted mean circulation
pattern across North America for the 6-10 day period. However, dynamical models
predict changes in the pattern over time, and differences in the timing of
changes between models increases the uncertainty of the forecast. A ridge
pushes northward during the period from the North Pacific into the Aleutians,
with the ECMWF ensemble predicting a more rapid increase in 500-hPa heights
over the state. All models predict a shortwave trough over the southwestern
contiguous U.S. (CONUS) early in the 6-10 day period. Positive 500-hPa height
anomalies over the northwestern CONUS are predicted to deamplify, as a trough
develops over the western CONUS and progresses eastward later in the period.
The GEFS ensemble mean predicts a more rapid eastward progression of this
trough than the ECMWF ensemble mean. Concurrently, models predict a trough and
associated negative 500-hPa height anomalies over the eastern CONUS to move
eastward into the Atlantic.

With a changing height pattern near-normal temperatures are favored over much
of Alaska. Below-normal temperatures are favored over northwestern Mainland
Alaska, consistent with the GEFS forecasts and the temperature consolidation.
Under the predicted trough and negative 500-hPa height anomalies, below-normal
temperatures are likely over most of the eastern CONUS, excluding the western
Great Lakes region and northern Maine, where above-normal temperatures are
favored, consistent with the temperature consolidation. Below-normal
temperatures are favored over much of the west coast and the interior
Northwest, as a trough develops over the region. Near-normal temperatures are
favored over most of the central CONUS, where temperature tools are
inconsistent. Above-normal temperatures are favored for parts of the Northern
Plains, consistent with most dynamical model forecast tools.

Above-normal precipitation is favored across southern and interior Mainland
Alaska and Southeast Alaska, east of a predicted trough axis over the
Aleutians. Below-normal precipitation is likely across most of the western
CONUS, under a predicted ridge through most of the period. Above-normal
precipitation is favored for the Southwest, Southern Plains, and Lower
Mississippi Valley, consistent with most dynamical model precipitation tools
and the precipitation consolidation. Near-to-above-normal precipitation is
favored across much of the northern central CONUS, as a trough develops in the
West. Below-normal precipitation is slightly favored over parts of the
Northeast and the southern Florida Peninsula, under anomalous northerly flow
behind the center of negative 500-hPa height anomalies over the Atlantic.

Above-normal temperatures and above-normal precipitation are favored for the
Hawaiian Islands, largely due to the influence of positive sea surface
temperature anomalies around the islands.

The official 6-10 day 500-hPa height blend consists of 35% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 15% of Today`s 6z GFS Ensemble Mean centered
on Day 8, 40% of Today`s 0z European Ensemble Mean centered on Day 8, and 10%
of Today`s 0z Canadian Ensemble Mean centered on Day 8


FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: About average, 3 out of 5, due to
good agreement among the dynamical model height forecasts and an amplified
pattern, offset by differences in temperature and precipitation tools and a
changing pattern.

8-14 DAY OUTLOOK FOR JAN 17 - 23 2025

Variations in the timing and amplitude of a trough developing over the West and
progressing across the CONUS leads to differences in ECMWF, GEFS, and Canadian
ensemble mean forecasts for the week-2 period. The GEFS predicts more rapid
eastward progression across the CONUS of a predicted trough, while the ECMWF
predicts a more amplified and less progressive trough over the west-central
CONUS. The ECMWF model also predicts greater amplification of the ridge over
western Alaska, while the GEFS deamplifies the ridge over the state later in
the period.

Above-normal temperatures continue to be favored over the eastern Aleutians and
southwestern and south-central Mainland Alaska, under the predicted ridge.
Below-normal temperatures are favored along the northwestern and northern
coasts of Mainland Alaska under primarily northerly flow. Below-normal
temperatures continue to be favored across most of the CONUS east of the
Rockies in week-2, excluding only northern Maine and South Texas, under a
predicted mean trough. Below-normal temperatures are favored for a small area
of Southern California and southwestern Arizona under a predicted shortwave
trough.

Above-normal precipitation is favored over southern Mainland Alaska and
Southeast Alaska, consistent with most dynamical model forecasts and the
precipitation consolidation. Below-normal precipitation is favored for much of
the western CONUS from the Pacific coast to the Great Basin, under positive
500-hPa height anomalies through much of the period. Above-normal precipitation
is favored from the Southwest and the Rocky Mountains eastward across most of
the CONUS, as the trough progresses across the CONUS. Probabilities for
above-normal precipitation are greater over the southeastern CONUS, with a
precipitation event predicted for this region during week-2. Near-normal
precipitation is favored for the Upper Mississippi Valley and northern areas of
the Northeast, where there is greater uncertainty in model forecasts.

Above-normal temperatures and above-normal precipitation continue to be favored
for the Hawaiian Islands, due to the influence of positive sea surface
temperature anomalies around the islands.

The official 8-14 day 500-hPa height blend consists of: 35% of Today`s 0z GFS
Ensemble Mean centered on Day 11, 15% of Today`s 6z GFS Ensemble Mean centered
on Day 11, 40% of Today`s 0z European Ensemble Mean centered on Day 11, and 10%
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 agreement among the dynamical model height forecasts, offset by
differences in temperature and precipitation tools and a changing mid-level
height pattern forecast.

FORECASTER: D Collins

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
January 16.


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:
20001227 - 20040119 - 19850110 - 19800122 - 19850119


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:
20001229 - 19800121 - 19770120 - 20040118 - 19850118


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

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



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

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

                           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.

$$