198
FXUS02 KWBC 220636
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
236 AM EDT Sat Aug 22 2026

Valid 12Z Tue Aug 25 2026 - 12Z Sat Aug 29 2026


...Hazardous heat to continue from the Lower Mississippi Valley
across the Southern Plains to the Desert Southwest...


...Overview and Guidance/Predictability Assessment...

The latest suite of guidance still has a well clustered consensus
for a stagnant upper pattern next week as highlighted by a strong
upper-high anchored over the Southwest and east-central U.S. mean
troughing. This ridge will continue to support multi-day hazardous
heat for much of the southern tier, particularly for the Southern
Plains and Lower Mississippi Valley. Along the ridge`s periphery
monsoonal moisture will promote scattered convection across the
Intermountain West and Rockies and strong convection with local
downpours spill across parts of the central states. Shortwaves will
maintain upper troughing over the east-central U.S. to favor wavy
and moderating frontal surges. Wrapping rains lingering over the
Northeast early next week as a lead low pulls away will be followed
by broad periods with organized rain/thunderstorms for portions of
the East/Southeast the rest of the week with wavy frontal systems.

...Weather/Hazards Highlights...

It remains the case that hot temperatures, some into the 100s with
oppressive heat indices, are forecast from the south-central U.S.
all next week under the strong upper high. Record- breaking warm
overnight temperatures across the southern tier will further limit
recovery from the heat, especially given heatwave longevity.
Widespread Major to Extreme HeatRisk will persist in the Southern
Plains and Lower Mississippi Valley. Several consecutive days of
high heat stress can lead to heat related illnesses. Farther west,
highs near and above 110 in the Desert Southwest could also cause
heat concerns next week. Areas of the Southeast may reach a few
degrees above normal at times with moist dewpoints and high heat
indicies. Please see WPC`s Key Messages for more details on the
extreme heat. Elsewhere, most areas will see near average
temperatures, with the Ohio Valley and vicinity below average.

A slowly exiting low will keep wrapping rain chances for the
interior Northeast early next week. Through much of this period,
monsoonal moisture is also forecast to bring scattered, diurnally
driven showers and thunderstorms to the Intermountain West/Rockies.
Isolated flash flooding is possible especially across sensitive
areas like burn scars, favored terrain like slot canyons and urban
areas. WPC Excessive Rainfall Outlook (ERO) Marginal Risk areas are
depicted into Tuesday and Wednesday. Areas of rain and strong to
severe storms are also possible into/out from the central U.S. as
shortwaves round the northeast side of the ridge and shift
southeast. Placement of these shortwaves and thus the rainfall
positions and amounts offer uncertainty over the central/east U.S.,
but frontal proximity and a pooling moisture/instability focus
over the central Plains prompted ERO Marginal Risk areas to further
monitor given training threat. Organized rain/thunderstorm chances
from the Midwest/Great Lakes early-mid next week will with wavy
frontal pushes increasingly spread over a hot/moist/unstable
East/Southeast next week. WPC ERO Marginal Risk areas have been
introduced for Tuesday/Wednesday given repeat multi-day potential.


Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast, excessive rainfall outlook,
winter weather outlook probabilities, heat indices and Key Messages
are at:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw










$$