Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 PM EDT Wed Jul 06 2022

Valid 00Z Thu Jul 07 2022 - 00Z Sat Jul 09 2022

...Widespread showers and thunderstorms with excessive rainfall and severe
weather possible through Friday from the High Plains to the East Coast...

...Dangerous heat and humidity to continue from parts of the
Central/Southern Plains to the Mid-Atlantic and Southeast...

...Mild temperatures and generally dry conditions forecast for New England
and the West...

Weather highlights and hazards for the short-term forecast period will be
largely dominated by a persistent upper-level ridge over the central U.S.
and a quasi-stationary frontal boundary draped from the Mid-Atlantic to
the High Plains. Upper-level disturbances moving southeastward along the
ridge as well as high surface moisture (low to mid-70s dewpoints) along
the frontal boundary will help to trigger widespread showers and
thunderstorms both Thursday and Friday, with multiple areas under the risk
of excessive rainfall and severe thunderstorms each day. For Thursday,
there are Slight Risks of excessive rainfall (level 2/4) for the coastal
Carolinas, the Middle-Mississippi/Ohio Valleys, and the Northern High
Plains. Slight Risks are also again in effect for the
Middle-Mississippi/Ohio Valleys and the southern Appalachians as well as
the coastal Carolinas on Friday. The combination of greater areal coverage
of rainfall from organized convective complexes, high moisture content
leading to efficient rainfall rates, and proceeding days of heavy rainfall
leading to more saturated soils will lead to the risk for isolated to
scattered instances of flash flooding. The Storm Prediction Center has
also issued Slight Risk outlook areas for severe thunderstorms (level 2/5)
from the Tennessee Valley to the Carolinas as well as the Northern Rockies
and High Plains on Thursday. Some thunderstorms may produce damaging
winds, and large hail will also be a threat in the Northern Rockies and
High Plains. A Slight Risk is also in effect for the Northern Rockies and
High Plains on Friday for the continued risk of scattered instances of
damaging winds and large hail. Thunderstorms in this region may also have
the tendency to grow upscale into organized convective lines in the
evening hours, enhancing the threat for damaging winds.

Meanwhile, a dangerous heat wave continues south of the frontal boundary
over the Central/Southern Plains to the southern Mid-Atlantic and
Southeast. High temperatures are forecast to be in the low 100s for most
of the Central/Southern Plains and east into the Mid-South and Tennessee
Valley. Mid- to upper 90s are expected elsewhere from the Ohio Valley to
the Mid-Atlantic and Southeast. These already hot temperatures will be
made even more uncomfortable when combined with the high humidity in place
across the region. Excessive Heat Warnings are in effect Thursday for
areas from Kansas City east to St Louis and Louisville and south to
Memphis as heat indices will soar into the 110-115 degree range.
Widespread Heat Advisories are also in effect for the region through
Friday for still very uncomfortable heat indices in the 105-110 degree
range. Just as concerning, low temperatures will remain very warm
overnight providing little relief from the sweltering conditions during
the day. Near record-tying/breaking forecast lows from the mid-70s to
low-80s are expected. 

Elsewhere, to the northeast of the ridge, temperatures will remain cooler
than normal for New England, with highs in the 70s along the coast and the
low 80s inland. An upper-level trough over the Pacific Northwest will also
keep temperatures cooler than normal for early July, with mostly 70s and
low 80s expected. However, conditions should remain mostly dry. High
temperatures for California and the Great Basin will tend to be around or
a bit cooler than normal, with 60s-70s along the immediate coast, 80s to
90s in the interior valleys, and 100s for the Desert Southwest.

Putnam

Graphics are available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php