254
FXUS02 KWNH 180758
PREEPD

Preliminary Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
357 AM EDT Sat Jul 18 2026

Valid 12Z Tue Jul 21 2026 - 12Z Sat Jul 25 2026


...Hazardous Heat to settle down across the South next week...


...Overview...

Very hot and moist conditions will focus over the South next week
as northern tier shortwaves and moderating surface fronts focus
rounds of locally heavy rains and strong to severe thunderstorms
from the Midwest/Great Lakes to the East. Lead activity over the
South/Southeast may be fueled by Gulf/tropical moisture. Elsewhere,
ample monsoonal moisture will continue to stream from the
Southwest and Intermountain West/Rockies and then the Plains to
fuel enhanced showers and thunderstorms as a closed upper high
shifts to the southern Plains. Meanwhile, current Tropical Storm
Elida is forecast by NHC to weaken into next week while lifting
northward well off the West Coast near 130W as a maritime threat.

...Guidance/Predictability Assessment...

Guidance is mainly agreeable on the large scale pattern, but
uncertainties are still evident with the smaller scale details
including local convective focus. A favored composite of best
clustered GFS/ECMWF/Canadian model/ensemble guidance and machine
learning guidance provides a solid forecast basis in line with the
National Blend of Models and WPC product continuity. Guidance still
shows uncertainty with energy and deep moisture pooling over the
northeast Gulf which could work slowly inland into next week. NHC
is monitoring this area currently with low probability of
formation, but regardless if it develops true tropical
characteristics, there is confidence for enhanced rainfall across
parts of the Florida and the Southeast into next week.

...Weather/Hazards Highlights...

Flow around a main upper ridge will continue to draw significant
monsoonal moisture into the Southwest and Intermountain
West/Rockies into next week. This moisture will lead to scattered
to numerous showers and thunderstorms with potential to produce
heavy rainfall and localized flash flooding. Sensitive places such
as burn scars, steep terrain, etc., would be the most vulnerable to
any flooding concerns that may develop. Broad Marginal and an
embedded Slight Risk of excessive rainfall have been introduced
from the Southwest into the Intermountain West for Tuesday into
Wednesday. Shower and thunderstorm coverage should gradually
increase eastward from the Rockies into the Plains next week as the
closed upper high shifts down to the southern Plains.

Upper ridge/closed high influence shift to the south will lead to
at least Major HeatRisks over much of the South next week as
temperatures 5-10F above already hot averages combine with high
humidity. Expect spotty record highs and more widespread record
overnight lows. Heat indices may rise to 105-110+F in some spots.

Elsewhere, heavy rains with strong to severe thunderstorms per SPC
are forecast to work through the Midwest/Great Lakes into early
next week given shortwaves aloft and wavy frontal push. As the
upper trough position amplifies and the fronts work southeast
through early-mid next week, heavy convective rain chances will
overspread much of the East, settling into the Southeast later next
week with slow wavy frontal progression. WPC Excessive Rainfall
Marginal Risk areas slowly shift eastward Tuesday and Wednesday
from the Ohio Valley to over the Mid-Atlantic and the Northeast.
An embedded Slight Risk area has also been introduced for Tuesday
over the central Appalachians.

Meanwhile to the South, energy is forecast to meander from the
northeastern Gulf in a moist and unstable environment into early
next week as monitored by NHC. Troughing and tropical moisture in
place (even if there is no true tropical low) may lead to heavy
rain and Marginal Risks are from northern Florida to the coastal
Southeast for isolated flash flooding for Tuesday into Wednesday.
There is some guidance signal to monitor that a combination of
system energies from the north and deeper Gulf/tropical moisture
may favor lingering heavy rain frontal focus extending into later
next week over the eastern Carolinas versus a shift just offshore.


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











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