919
FXUS06 KWBC 091926
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Sat May 09 2026

6-10 DAY OUTLOOK FOR MAY 15 - 19 2026

Today`s numerical models depict a transitional 500-hPa flow pattern across much
of North America and surrounding regions. The period begins with an elongated
mid-level trough with an axis just below the southern Alaska coastline toward
southwestern Canada and the Pacific Northwest. Farther east, there is another
shortwave trough, with its axis through New England to off the Mid-Atlantic
Coast. Between these features, an anomalous mid-level ridge extends from the
Southwest through the central Contiguous United States (CONUS). With time,
rising heights from the central North Pacific erode the mid-level trough near
northwestern North America while a strong mid-level trough near Siberia moves
eastward toward Alaska, becoming centered near the Bering Sea by the end of the
period. Farther east, the mid-level pattern is progressive for the first half
of the period. The mid-level trough over the Northeast moves away from the
CONUS and weakens while, farther west, the broad 500-hPa ridge over the central
CONUS shifts eastward, with its axis extending approximately from the central
Gulf Coast northward through the Great Lakes by the middle of the period.
Thereafter, the 500-hPa height pattern becomes less progressive. The broad
500-hPa ridge over the central and eastern CONUS broadens during the last half
of the period, eventually covering a large part of the central and eastern
CONUS, but there is poor agreement among the models on the details of this
pattern evolution. It appears to be a complex situation in terms of day-to-day
fluctuations in this mid-level ridge, and the models are not in good agreement
on the specifics of the pattern evolution after mid-period, but all ensemble
means agree that the mid-level ridge will stall while over the central and
eastern CONUS. Thereafter, the ridge may build northward, or expand westward,
drifting around the central and eastern CONUS without its axis making any net
progress eastward toward the western North Atlantic. To the west, a relative
mid-level trough is expected to form along or near the western North America
Coast, the result of building heights in the central North Pacific and the
persistent 500-hPa ridge that stalls over the central and eastern CONUS. By the
end of the period, a broad 500-hPa ridge covers much of the interior and
eastern CONUS with weak mid-level troughing in marginally below-normal heights
near the western CONUS coastline. Meanwhile, near-normal 500-hPa heights cover
Alaska between a strong trough centered near the Bering sea and a mid-level
ridge likely building in the central North Pacific. The GEFS mean is a bit of
an outlier, being weaker with the trough near the Bering Sea and squelching any
ridge development in the central North Pacific. Most other guidance is more
amplified with both of these features, and for that reason the more amplified
solutions are preferred. Near normal 500-hPa heights are expected across Hawaii
south of the building central North Pacific mid-level ridge, with a minor
increase in mid-level heights possible by the end of the period.

Above normal temperatures are favored across most of the CONUS as expansive
ridging in the central CONUS expands eastward to cover most of the CONUS from
the interior West to the Atlantic Seaboard. Chances for unseasonable warmth
exceed 60 percent across a broad portion of the interior CONUS, from parts of
the eastern Rockies through a large part of the Plains and Mississippi Valley,
and across the Tennessee Valley. Lesser enhanced odds for above-normal
temperatures cover most of the rest of the CONUS, excepting only a portion of
the Pacific Northwest. Chances for warmth were reduced relative to the
autoblend in both the western and eastern CONUS due to colder solutions in
those regions in the raw ensemble outputs and the analogs. Across most of
Alaska, as the trough centered south of the state dissipates, temperatures are
likely to average close to normal, with enhanced odds for warmth restricted to
the northwestern  Mainland in southerly mid-level flow downstream from the
mid-level trough encroaching from the west. Above normal temperatures are
strongly favored for Hawaii, with the greatest odds (over 80 percent) across
the southern half of the Big Island, consistent with the consolidation tool and
with above normal sea surface temperatures (SSTs) in the adjacent Pacific.

An active pattern is favored for central and southern Alaska as strong
mid-level troughing builds across the Bering Sea while the subnormal heights
south of the state dissipate. Confidence in surplus precipitation is highest
(greater than 40 percent) across the southern tier of the state. Across the
CONUS, the mid-level pattern is likely to induce surface low pressure somewhere
across the Plains. Circulation around this feature, along with southerly flow
from high pressure over the Southeast, is expected to establish a strong fetch
of moist air from the tropics into the central CONUS. These factors raise the
odds for surplus precipitation in a swath through the central tier of the
CONUS, particularly in the south-central States closest to the tropical air
influx and southeast of the most likely location of surface low pressure
development. The likelihood of above-normal precipitation exceeds 50 percent
over much of central and western Texas and some adjacent locales.
Marginally-enhanced chances for wetter than normal weather reach northward
through the Great Lakes, and also cover parts of the northwestern and
northeastern CONUS, consistent with the consolidation tool and (to a lesser
extent) some of the analogs. Meanwhile, surface high pressure southeast of the
mid-level ridge center would favor subnormal precipitation in much of the
Southeast, with odds exceeding 40 percent over much of the Carolinas, Georgia,
and northern Florida. Drier than normal conditions are also slightly favored
over parts of the western Rockies, Great Basin, and central West Coast. The
consolidation tool favors wetter than normal wetter across Hawaii, and this is
reflected in the official forecast, with the best chances for wet weather over
the southeastern half of the Big Island.

The official 6-10 day 500-hPa height blend consists of 18% of Today`s 6z GFS
Ensemble Mean centered on Day 8, 8% of Today`s operational 0z GFS centered on
Day 8, 40% of Today`s 0z European Ensemble Mean centered on Day 8, 9% of
Today`s operational 0z ECMWF centered on Day 8, and 25% of Today`s 0z Canadian
Ensemble Mean centered on Day 8


FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Below average, 2 out of 5, due to
fair model agreement at best on a complex pattern that transitions away from
being progressive, along with some significant inconsistencies between the raw
and statistically-adjusted ensemble outputs, with further uncertainty
introduced by analogs.

8-14 DAY OUTLOOK FOR MAY 17 - 23 2026

During the week-2 period, the expansive mid-level ridge looks to persist in
covering a large part of the CONUS. This feature doesn`t move significantly and
most of the guidance shows it continuing to affect a large part of the CONUS
through the end of week-2, but it waxes and wanes with time in ways not
consistently depicted in the tools, increasing uncertainty. All of the ensemble
means show this feature continuing to affect much of the CONUS through the end
of week-2, and the ECENS and CMCE means both hint at the potential for some
strengthening of this mid-level ridge late in the period, although they are not
in good agreement on where maximum positive 500-hPa height anomalies may end
up. The uncertainty is further increased by poor agreement on a mid-level
trough that may impact the Northeast toward the end of week-2, with the GEFS
showing this feature pushing farther south and at least temporarily suppressing
the ridge covering most of the central and eastern CONUS. The ECENS and CMCE
means are less amplified with this trough, restricting significant effects to
southeastern Canada and parts of the immediately adjacent CONUS. The
less-amplified solution is favored since it is depicted by a majority of the
guidance, but a more intrusive trough can`t be ruled out. Farther west, weak
troughing is expected to generally persist near the West Coast, although there
is significant model spread regarding the evolution of this feature, with the
guidance being inconsistent in how the strength and location of this feature
morphs with time. Meanwhile, a similar situation looks to set up over and near
Alaska, with guidance in agreement showing fairly strong mid-level troughing
west or southwest of Mainland Alaska, but in considerably less agreement on how
the position and strength of this and surrounding features change with time.
With a mid-level ridge expected to build in the central North Pacific, heights
to the south across Hawaii are expected to creep slightly above normal with
time, as depicted in the ECENS and CMCE means.

Above normal temperatures are likely to dominate most of the CONUS under the
strong influence of the persistent mid-level ridge. Odds at least marginally
favor warmer than normal weather throughout the CONUS, except across northern
Maine. A preponderance of the tools show the greatest likelihood for
above-normal temperatures (over 60 percent) covering the Southeast.
Northwestern  Mainland Alaska also had enhanced chances for anomalous warmth,
but uncertainty elsewhere across the state favors near normal temperatures.
Across Hawaii, a strong likelihood of above normal temperatures continues.

An active pattern is more likely than not to impact Alaska, keeping enhanced
chances for wetter than normal conditions across central and southern sections
of the state, with the highest odds (over 40 percent) along the southern tier.
The pattern across the CONUS is similar to the 6-10 day precipitation forecast,
with enhanced moist southerly flow favoring wetter than normal conditions over
a broad swath across the central CONUS, with the best chances (over 50 percent)
closer to the moisture source across a large part of Texas and some adjacent
locations. Meanwhile, near or just downstream from the mid-level ridge axis,
the eastern fringes of the Mid-Atlantic and lower Northeast have
marginally-enhanced chances for subnormal precipitation. This is derived from a
combination of the ensemble reforecast precipitation tools and some of the
analogs, which are not in particularly good agreement on the placement of this
area. Above normal precipitation remains favored for Hawaii, consistent with
consolidated skill-weighted precipitation amounts from the ECMWF and GEFS
Ensembles.

The official 8-14 day 500-hPa height blend consists of: 21% of Today`s 6z GFS
Ensemble Mean centered on Day 11, 6% of Today`s operational 6z GFS centered on
Day 11, 48% of Today`s 0z European Ensemble Mean centered on Day 11, and 25% 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, brought
down by model inconsistencies in the detailed evolution of mid-level features
with time and among the various precipitation tools.

FORECASTER: Rich Tinker

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 May
21.


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:
20200422 - 20040430 - 20210421 - 20080518 - 19900503


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:
20200422 - 19950522 - 20080519 - 20210421 - 19900504


6-10 DAY OUTLOOK TABLE
Outlook for May 15 - 19 2026

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  N    A     OREGON      A    N     NRN CALIF   A    B
SRN CALIF   A    N     IDAHO       A    N     NEVADA      A    B
W MONTANA   A    N     E MONTANA   A    N     WYOMING     A    N
UTAH        A    N     ARIZONA     A    N     COLORADO    A    A
NEW MEXICO  A    A     N DAKOTA    A    N     S DAKOTA    A    N
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    N     MISSISSIPPI A    N     MICHIGAN    A    A
INDIANA     A    N     OHIO        A    N     KENTUCKY    A    N
TENNESSEE   A    N     ALABAMA     A    B     NEW YORK    A    N
VERMONT     A    A     NEW HAMP    A    N     MAINE       A    A
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    B
N CAROLINA  A    B     S CAROLINA  A    B     GEORGIA     A    B
FL PNHDL    A    B     FL PENIN    A    N     AK N SLOPE  N    N
AK ALEUTIAN N    A     AK WESTERN  N    A     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 May 17 - 23 2026

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    A     OREGON      A    N     NRN CALIF   A    N
SRN CALIF   A    A     IDAHO       A    N     NEVADA      A    N
W MONTANA   A    N     E MONTANA   A    N     WYOMING     A    N
UTAH        A    A     ARIZONA     A    A     COLORADO    A    A
NEW MEXICO  A    A     N DAKOTA    A    N     S DAKOTA    A    N
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       N    N
MASS        A    N     CONN        A    B     RHODE IS    A    B
PENN        A    N     NEW JERSEY  A    B     W VIRGINIA  A    N
MARYLAND    A    B     DELAWARE    A    B     VIRGINIA    A    N
N CAROLINA  A    N     S CAROLINA  A    N     GEORGIA     A    N
FL PNHDL    A    N     FL PENIN    A    N     AK N SLOPE  A    N
AK ALEUTIAN N    A     AK WESTERN  A    A     AK INT BSN  N    A
AK S INT    N    A     AK SO COAST N    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.

$$