283
FXUS06 KWBC 031901
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Fri October 03 2025

6-10 DAY OUTLOOK FOR OCT 09 - 13 2025

The GEFS and ECENS remain in good agreement that an Omega block develops over
the North Pacific and western North America during the second week of October.
The highly amplified blocking pattern is forecast to consist of a: trough over
the Kamchatka Peninsula, an Alaskan ridge, and a trough along the West Coast.
The ECENS depicts a positive 500-hPa height anomaly of +300 meters near the
Alaska Peninsula for this 5-day period. The ECENS and GEFS are in better
agreement today over the central and eastern CONUS with a strong, persistent
500-hPa ridge, while the CMCE is an outlier with a trough near the East Coast.
Since the ECENS has the best daily continuity, the manual 500-hPa height blend
was weighted most heavily with this model solution.

Despite the expectation for an amplifying 500-hPa ridge upstream over Alaska
which can typically lead to an outbreak of colder-than-normal temperatures for
the lower 48 states, above-normal temperatures are favored for a majority of
the CONUS. This mild temperature pattern is due to the lack of any sustained
anomalous northerly flow at the mid to high latitudes of North America through
mid-October. The largest above-normal temperature probabilities (greater than
70 percent) are forecast for the central to southern Great Plains where 5-day
temperatures are likely to average more than 10 degrees F warmer-than-normal.
Since model guidance has trended towards a more amplified 500-hPa trough along
the West Coast, an increased chance of below-normal temperatures is forecast
across the Pacific Northwest, California, and western Nevada. Near-normal
temperatures are most likely for parts of the Northeast where temperatures are
predicted to transition from below to above from days 6 to 8.

The National Hurricane Center (NHC) is monitoring a broad area of low pressure
a few hundred miles offshore of southwestern Mexico and tropical cyclone (TC)
development is imminent. Model solutions indicate that a second TC could form
just offshore of southwestern Mexico later next week. Although model spread
remains large on the exact track of these potential TCs across the East
Pacific, anomalous low to mid-level moisture is likely to overspread the
western CONUS by day 6, October 9. This enhanced moisture coupled with the
amplified 500-hPa trough along the West Coast supports an increased chance of
above-normal precipitation throughout the western CONUS. The largest
above-normal precipitation probabilities (exceeding 60 percent) are forecast
for the Southwest and southern California. Above-normal precipitation is also
favored for the northern to central Great Plains and Upper Mississippi Valley
as a shortwave trough may eject from the longwave trough upstream along the
West Coast. Broad surface high pressure, predicted by all the ensemble mean
solutions, is expected to result in below-normal precipitation from the
Northeast southwestward to the Lower Mississippi Valley and southern Great
Plains. Easterly flow and a break in the subtropical ridge supports an
increased chance of above-normal precipitation across the coastal Southeast,
Florida Peninsula, and southern Texas.

Forecast confidence is high across Alaska with models remaining consistent that
a highly amplified trough centered over the Kamchatka Peninsula likely spawns
multiple surface low pressure systems tracking into the Bering Sea. These low
pressure systems and associated onshore flow favor above-normal temperatures
and above-normal precipitation for much of Alaska. The one exception to the wet
pattern is over southeastern Alaska, which would be downstream of the 500-hPa
ridge axis leading to an elevated chance of below-normal precipitation.

Based on the GEFS and ECENS, above-normal temperatures and above-normal
precipitation are favored for Hawaii.

The official 6-10 day 500-hPa height blend consists of 35% of Today`s 0z GFS
Ensemble Mean centered on Day 8, and 65% of Today`s 0z European 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 the precipitation and temperature tools throughout most of
the forecast domain.

8-14 DAY OUTLOOK FOR OCT 11 - 17 2025

The preferred ECENS and GEFS are in good agreement with a 500-hPa ridge
extending from the Gulf of Alaska northward to eastern Mainland Alaska, a
trough along the West Coast of the CONUS, and a broad mid-level ridge over the
central and eastern CONUS. The CMCE was an outlier today with its lower 500-hPa
heights across the East. Towards the end of week-2, the ECENS and GEFS depict
the amplified Alaskan ridge quickly weakening but forecast confidence on this
timing is low. The broad 500-hPa ridge with associated positive height
anomalies support an increased chance of above-normal temperatures for the
eastern two-thirds of the CONUS. Above-normal temperature probabilities exceed
60 percent across most of the Great Plains and Mississippi Valley which is
consistent with the largest 500-hPa height anomalies. Probabilities are reduced
to the east of the Appalachians since recent model runs have favored a
transient trough developing along the East Coast. Due to the amplified 500-hPa
trough along the West Coast, near to below-normal temperatures are favored
across the Pacific Northwest, Great Basin, Desert Southwest, and California.

By the beginning of week-2, anomalous low to mid-level moisture is likely to be
well-established throughout the western CONUS. The amplified 500-hPa trough
along the West Coast along with this enhanced moisture support an increased
chance of above-normal precipitation across that region. Above-normal
precipitation probabilities are maximized for Arizona where climatology is
lower but also based on a model consensus. The ECENS favors surface low
development across the northern high Plains on day 8 with a subsequent
northeastward track. Therefore, the outlook leans slightly on the wet side for
the northern to central Great Plains and Upper Mississippi Valley. Due to the
broad ridge aloft and a storm track likely displaced northward of its typical
location during mid-October, below-normal precipitation is favored for much of
the eastern and south-central CONUS. It was notable that the GEFS reforecast
trended much drier today across the southern Great Plains and Lower Mississippi
Valley and aligns better with its uncalibrated model output. A persistent
weakness in the subtropical ridge supports elevated above-normal precipitation
probabilities across the coastal Southeast and Florida Peninsula. A tropical
wave has just moved west from Africa and as of 2pm EDT on October 3, NHC states
that there is a 50 percent chance of TC development across the Main Development
Region of the Atlantic within the next seven days. In addition, there could be
an increasing chance of TC genesis across the Caribbean Sea later in week-2.
Therefore, the tropics will have to be closely monitored in subsequent
outlooks.

Similar to the 6-10 day period, southwesterly onshore flow strongly favors
above-normal temperatures throughout Alaska. The enhanced onshore flow also
supports an increased chance of above-normal precipitation for much of Alaska.
Downstream of the mid-level ridge axis, near to below-normal precipitation is
more likely for parts of southeastern Alaska.

Based on the GEFS and ECENS, above-normal temperatures and above-normal
precipitation are favored for Hawaii. Positive sea surface temperature
anomalies also support above-normal temperatures, especially across the
northwestern islands.

The official 8-14 day 500-hPa height blend consists of: 35% of Today`s 0z GFS
Ensemble Mean centered on Day 11, and 65% of Today`s 0z European Ensemble Mean
centered on Day 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Average, 3 out of 5, due to good
agreement among most of the temperature and precipitation tools offset by
uncertainty on how fast the Omega block over the North Pacific and western
North America breaks down later in week-2.

FORECASTER: Brad Pugh

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
October 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:
20071007 - 20040919 - 19621002 - 20080922 - 20010928


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:
20040920 - 20071007 - 19981013 - 19621003 - 19730928


6-10 DAY OUTLOOK TABLE
Outlook for Oct 09 - 13 2025

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



8-14 DAY OUTLOOK TABLE
Outlook for Oct 11 - 17 2025

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

$$