Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
356 PM EDT Sat Jul 01 2023

Valid 00Z Sun Jul 02 2023 - 00Z Tue Jul 04 2023

...Heavy rain with the risk of localized flash flooding and severe weather
stretching from the Northeast to the Mid-South Sunday...

...Excessive heat continues for portions of the South as well as
California and the Desert Southwest...

...Much above normal temperatures for portions of the Northern Plains and
Upper-Midwest ahead of rain/storm chances Monday...

An eastward moving upper-level wave/surface frontal system over the
Midwest Saturday will slowly push eastward Sunday, providing the focusing
mechanisms and upper-level lift to fuel widespread showers and storms from
the Northeast southwest through the Mid-Atlantic, Ohio Valley, and into
the Mid-South.  Southerly flow ahead of the system will keep plenty of
moisture in place to fuel these storms and lead to the potential for heavy
downpours and locally heavy rainfall totals. A Slight Risk of Excessive
Rainfall (level 2/4) is in place from interior New England southwest
through the northern Appalachians and Upper Ohio Valley where the best
combination of forcing/CAPE will reside and wet antecedent conditions due
to recent rainfall may lead to a few instances of flash flooding.
Additionally, there is a Slight Risk of severe weather (level 3/5)
stretching from the Mid-Atlantic southwestward through the
central/southern Appalachians, Tennessee Valley, and into the Mid-South.
Moderately strong flow aloft as the upper-wave moves overhead should
provide enough deep-layer shear to lead to some organized storms/storm
clusters with the risk of large hail and damaging winds. Shower and storm
chances will continue Monday as the frontal system slowly pushes eastward
towards the East Coast, although with a more limited risk of heavy
rainfall and severe weather. Generally average summer highs in the upper
80s to low 90s are forecast for most of the region. Highs will be below
normal Sunday in New England and portions of the Interior Northeast north
of a warm front, with 70s forecast. As the warm front lifts northward
Monday, highs will warm up into the 80s for most locations.

Meanwhile, the heat continues for portions of the South as well as
California and the Desert Southwest. Although conditions will be a little
better Sunday than Saturday in the South, highs will once again be in the
mid- to upper 90s for most locations as an upper-level ridge remains
overhead. When combined high humidity, heat indices will soar as high as
110 degrees, particularly for the Lower Mississippi Valley. A weak frontal
boundary moving into the region and the upper-level ridge shifting
eastward will bring a little relief on Monday, with highs a few degrees
cooler. However, conditions will stay hot further east in the Southeast
and into the Carolinas as the ridge pushes eastward, with highs into the
upper 90s. Also notable is a continued stretch of forecast near-record and
record-tying/breaking highs for Florida in the mid- to upper 90s which
looks to continue beyond the current forecast period. Excessive heat will
also remain in place Sunday over portions of interior California and the
Desert Southwest Sunday under another upper-level ridge. Forecast highs
will range from 110-115 for the deserts, 105-110 degrees for the central
California valleys, and upper 90s to low 100s for other lower-elevations
of California outside of the immediate coast. A few record-tying/breaking
highs will be possible. An upper-level trough moving in on Monday will
bring temperatures down a bit over northern and central California while
the heat continues for the Desert Southwest. Highs will also be above
average in the Great Basin, with mid-90s to low 100s forecast, as well as
into the Pacific Northwest, with 80s for most locations other the coast
and Puget sound, where highs will be in the 70s.

Showers and storms will linger for much of the Midwest and Great Lakes
region as the frontal system pushes eastward while a warm up is in store
for the Upper Midwest. Highs in the 80s to low 90s on Sunday will jump as
high as the mid-90s on Monday. Some areas may still see some poor air
quality due to smoke from Canadian wildfires, but conditions should
continue to improve as the smoke tends to disperse over the next couple of
days. Another frontal system over south-central Canada will push southward
into the Northern Rockies/Northern Plains through the day Sunday and into
Monday, with increasing precipitation chances across the region and the
potential of some locally heavy rainfall. Highs on Sunday in the 80s to
low 90s will drop into the 70s behind the cold front.

Putnam

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