005
FXUS06 KWBC 171901
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Thu April 17 2025

6-10 DAY OUTLOOK FOR APR 23 - 27 2025

Multi-model ensemble means (GEFS, ECENS, and CMCE) depict a persistent longwave
trough-ridge pattern from west-to-east over the Contiguous U.S. (CONUS) through
late April. Positive 500-hPa height anomalies along with southerly surface flow
favor above-normal temperatures from the Great Plains to the East Coast. Large
probabilities (exceeding 70 percent) are forecast for the Southeast where 5-day
temperatures are forecast to average near 10 degrees F above normal.
Above-normal temperature probabilities are slightly lower across the Northeast
due to close proximity of negative sea surface temperature anomalies offshore
and an increased chance of at least brief periods of easterly flow during this
5-day period. Despite the predicted 500-hPa trough over the western CONUS,
temperature tools are in good agreement with elevated above-normal temperature
chances for most of this region. Based on the automated and skill-weighted
consolidation, near to below-normal temperatures are most likely for California
and portions of the Desert Southwest.

On day 6 and 7 (April 23 and 24), model solutions remain consistent and in good
agreement that a front becomes stationary across the Southern to Central Great
Plains, Lower to Middle Mississippi Valley, and Tennessee Valley. This
stationary front is likely to be a focus for heavier precipitation and
above-normal probabilities are maximized within this corridor. The GEFS and
ECENS depict 5-day precipitation amounts exceeding 1.5 inches for Arkansas,
eastern Oklahoma, and northeastern Texas. Later in this period, the GEFS,
ECENS, and CMCE depict a shortwave trough progressing east over the western
CONUS which would lead to surface low development somewhere to the lee of the
Rockies. This evolving pattern aloft and at the surface favors above-normal
precipitation for a majority of the western and central CONUS. A cold frontal
passage is predicted during this 5-day period for the Great Lakes and
Mid-Atlantic where a slight lean towards above-normal precipitation is
forecast.

Model solutions, especially the ECENS, feature the development of anomalous
500-hPa troughing over the Bering Sea and Aleutians. This upstream trough and
associated southwesterly flow favor near to above-normal temperatures and
above-normal precipitation across the southern half of Alaska. Nearby surface
high pressure and northeasterly flow support increased below-normal temperature
probabilities for much of northern and eastern Alaska.

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 20% of Today`s 6z GFS
Ensemble Mean centered on Day 8, 50% 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 model agreement and a persistent longwave pattern.

8-14 DAY OUTLOOK FOR APR 25 - MAY 01, 2025

The GEFS, ECENS, and CMCE maintain a 500-hPa trough (ridge) over the western
(eastern) CONUS through at least the end of April. By the end of week-2, the
ECENS is the most amplified with the mid-level trough extending from the Gulf
of Alaska southeastward to the West Coast. The GEFS appears to be an outlier
today with its solution of lower 500-hPa heights over the mid to high latitudes
of eastern North America. A broad area of positive 500-hPa height anomalies
coupled with a lack of any cold air advection, consistent among all the
ensemble means, support increased above-normal temperature probabilities for
nearly all of the lower 48 states. Due to more anomalous 500-hPa troughing,
above-normal temperature probabilities were smaller west of the Rockies with
near normal temperatures forecast for much of Arizona and California.
Below-normal temperatures are favored for southern California as onshore flow
and widespread cloudiness tilt the week-2 outlook towards the
cooler-than-normal side.

At the beginning of week-2, a stationary front is expected to be located from
the Central to Southern Great Plains eastward to the Ohio and Tennessee Valleys
and Mid-Atlantic. By day 10 (April 27), another shortwave trough is forecast to
enter the western CONUS with leeside cyclogenesis likely somewhere across the
Great Plains. Overall, the week-2 outlook leans on the wetter side for much of
the central and western CONUS with the largest probabilities centered across
the Great Plains. Compared to the 6-10 day period, the 8-14 day outlook is
drier across the Southeast as a front lifts north of this region. Based on the
uncalibrated ECENS, below-normal precipitation is slightly favored for parts of
the Southeast. Since the ECENS with its more amplified trough upstream and
enhanced onshore flow was preferred today, the week-2 precipitation outlook
leans wet for the Pacific Northwest along with much of California and Nevada.

A broad trough is forecast over the Bering Sea and Aleutians. Downstream of
this broad trough, above-normal precipitation is favored for the southern-two
thirds of Alaska. The enhanced onshore flow leads to increased chances of
above-normal temperatures for southern Alaska, while nearby surface high
pressure and easterly flow favor below-normal temperatures across northern
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 throughout Hawaii.

The official 8-14 day 500-hPa height blend consists of: 20% of Today`s 6z GFS
Ensemble Mean centered on Day 11, 50% 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: Above average, 4 out of 5, due to
good model agreement on a fairly stable longwave pattern for this time of year.

FORECASTER: Brad Pugh

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 May
15.


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:
20000330 - 19610405 - 19900404 - 19990421 - 19750328


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:
19990420 - 20000330 - 20020330 - 19700327 - 19610404


6-10 DAY OUTLOOK TABLE
Outlook for Apr 23 - 27 2025

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



8-14 DAY OUTLOOK TABLE
Outlook for Apr 25 - May 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      A    A
W MONTANA   A    A     E MONTANA   A    A     WYOMING     A    A
UTAH        A    N     ARIZONA     N    N     COLORADO    A    A
NEW MEXICO  A    A     N DAKOTA    A    A     S DAKOTA    A    A
NEBRASKA    A    A     KANSAS      A    A     OKLAHOMA    A    A
N TEXAS     A    A     S TEXAS     A    A     W TEXAS     A    A
MINNESOTA   A    A     IOWA        A    A     MISSOURI    A    A
ARKANSAS    A    A     LOUISIANA   A    N     WISCONSIN   A    A
ILLINOIS    A    N     MISSISSIPPI A    N     MICHIGAN    A    A
INDIANA     A    N     OHIO        A    A     KENTUCKY    A    N
TENNESSEE   A    N     ALABAMA     A    N     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    A
MARYLAND    A    N     DELAWARE    A    N     VIRGINIA    A    N
N CAROLINA  A    N     S CAROLINA  A    N     GEORGIA     A    N
FL PNHDL    A    B     FL PENIN    A    B     AK N SLOPE  B    N
AK ALEUTIAN A    A     AK WESTERN  N    A     AK INT BSN  B    A
AK S INT    A    A     AK SO COAST A    A     AK PNHDL    A    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.

$$