919
FXUS21 KWNC 111852
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT May 11 2026

SYNOPSIS: Forecast mid-level high pressure across the eastern contiguous U.S.
(CONUS) favors a more favorable pattern for unseasonably warm springtime
temperatures east of the Rockies, with possible extreme heat conditions from
the Middle Mississippi Valley eastward to the Mid-Atlantic. Surface low
development in the lee of the Rockies supports an increased risk of heavy
precipitation along with episodes of high winds across portions of the Great
Plains and Mississippi Valley. Meanwhile, decreasing mid-level high pressure
over the western CONUS may also bring episodes of high winds across coastal
California and Oregon early in week-2.

HAZARDS

Slight risk of extreme heat for portions of the Lower Mississippi, Tennessee
and Ohio Valleys, Southern Appalachians, Southeastern U.S., and Mid-Atlantic,
Tue-Thu, May 19-21.

Moderate risk of heavy precipitation for portions of the Southern Plains and
Lower Mississippi Valley, Tue-Wed, May 19-20.

Slight risk of heavy precipitation for portions of the Southern Plains, Middle
and Lower Mississippi, Ohio, and Tennessee Valleys, and Southeastern U.S.,
Tue-Thu, May 19-21.

Slight risk of high winds for much of coastal California and Oregon, Tue-Wed,
May 19-20.

Slight risk of high winds for portions of the Rockies and the Northern and
Central Plains,  Tue-Wed, May 19-20.

DETAILED SUMMARY

FOR THURSDAY MAY 14 - MONDAY MAY 18:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR TUESDAY MAY 19 - MONDAY MAY 25: Dynamical models continue to indicate a
potentially significant pattern change by the weekend into week-2. Following
the current and recent period characterized by persistent 500-hPa ridging
(troughing) over much of the western (eastern) CONUS, a transition is
anticipated by this weekend through week-2 to ridging (troughing) across the
East (West). This pattern favors unseasonably warm spring temperatures across
the East, with increased potential for enhanced precipitation across the
south-central into east-central CONUS ahead of the western mid-level trough.



There is better consensus among models, compared to yesterday, indicating more
amplified ridging across the East and troughing across the West peaking at the
end of week-1, lingering until the beginning of week-2. This translates to
increased signals for anomalous heat across parts of the East. Due to
temperatures in the dynamical model guidance being below 100 deg F, a moderate
risk of extreme heat was not designated. A slight risk is designated for
portions of the Lower Mississippi, Tennessee and Ohio Valleys, Southern
Appalachians, Southeastern U.S., and Mid-Atlantic May 19-21 where there is at
least a 20% chance of maximum temperatures exceeding the 85th percentile
climatologically and 90 deg F. The GEFS (ECENS) Probabilistic Extremes Tool
(PET) shows the greatest likelihood of at least a 40% (60%) chance of maximum
temperatures exceeding these thresholds across Virginia and the Carolinas.
Uncalibrated guidance from the GEFS and ECENS shows at least a 20% chance of
temperatures exceeding 95 deg F in some areas across the East Coast. The
National Blend of Models (NBM) indicates possible near or record breaking
temperatures in the Mid-Atlantic and some lower elevation adjacent areas just
west of the Southern Appalachians.



Surface low formation is predicted across the Southern Plains and Mississippi
Valley  ahead of the mid-level trough across the West. With anticipated surface
high pressure remains favored over the southeastern U.S. and into the western
Atlantic, low-level southerly enhanced moist flow also increases the risk of
heavy precipitation across portions of the south-central and east-central
CONUS, with conditions possibly being conducive to thunderstorms across some
areas. A moderate risk of heavy precipitation is posted for portions of the
Southern Plains and Lower Mississippi Valley May 19-20, where PETs indicate at
least a 30-40% chance of exceeding one inch in a 3-day period, with the first
two days of week-2 being the focus of the heaviest precipitation, further
supported by uncalibrated ensemble totals. A broader area is highlighted with a
slight risk across parts of the Southern Plains, Middle and Lower Mississippi,
Ohio, and Tennessee Valleys, and Southeastern U.S. through May 21, where PETs
indicate at least a 20% chance of 3-day accumulated totals exceeding  the 85th
percentile and one inch. Flash flooding is possible in some areas with
anticipated rainfall during week-1 and the beginning of week-2, especially in
some areas in the Deep South that are currently experiencing river flooding.



The mean troughing over the western CONUS, along with potential for shortwave
activity, supports the continuation of the slight risks of high winds across
portions of the West Coast as well as over the Interior West and High Plains,
tied to surface low development (both valid through May 20). Both the GEFS and
ECENS PETs continue to show at least 20% chances for wind speeds exceeding the
85th percentile from Oregon southward to southern California, and Northern
Plains. A broader area is highlighted across the Central and Northern Plains
where uncalibrated wind tools show increased chances for gusts exceeding 34kts
(~40mph). Gusty conditions combined with anticipated anomalous warmth, and
antecedent dry conditions may increase the risk for wildfires. The National
Interagency Fire Center (NIFC) shows moderate risk of significant fire
potential across parts of the Rockies and Great Plains, with localized areas
currently experiencing active wildfires.



In Alaska, the typical peak of the river ice breakup season is approaching, and
ice jam flooding can occur this time of year with little or no notice as
conditions on frozen rivers can change quickly. Please check with the Alaska
Pacific River Forecast Center for the latest conditions and advisories.

FORECASTER: Melissa Ou

$$