Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
428 AM EDT Fri Jun 30 2023

Valid 12Z Fri Jun 30 2023 - 12Z Sun Jul 02 2023

...More severe thunderstorms and areas of heavy rain to track eastward
from the central Plains to the Ohio Valley for the next couple of days...

...Excessive Heat Warnings and Advisories across much of California into
the Desert Southwest as well as through the lower and mid-Mississippi
Valley...

...Air Quality alerts over parts of the Midwest, Great Lakes, central
Appalachians, Northeast, and Mid-Atlantic...

A wavy front will continue to be the focus for severe thunderstorms and
areas of heavy rain to track eastward from the central Plains to the Ohio
Valley for the next couple of days.  The heaviest and strongest storms are
expected to gradually shift farther east each day as a better-defined low
pressure wave reaches into the lower Great Lakes by Sunday morning. 
Thunderstorm complexes that develop along the front will likely contain
heavy downpours, hail, along with damaging wind gusts, with the best
chance of these to occur over the mid-Mississippi and Ohio Valleys later
on Saturday per the Storm Prediction Center.  The gradual eastward shift
of the severe weather is in response to upper-level impulses ejecting from
the western U.S. upper trough.  The impulses will begin to erode the upper
ridge responsible for the ongoing heat wave across the South and help
bringing cooler air ever so slowly east across the central Plains.  The
hottest temperatures into the triple-digits are forecast to reach the
northern-most locations in Missouri today while more oppressive humidity
will continue farther south closer to the Gulf Coast. 

As the cooler air reaches into the central Plains through the next couple
of days, heat will begin to build further up along the West Coast and then
reach into the northern Plains by Sunday.  The interior valleys of central
and northern California will see afternoon temperatures climbing well up
into the 100s to near 110 degrees at the hottest locations on Saturday,
while the Desert Southwest will see high temperatures reaching well up
into the 110s.  These temperatures will increase the risk of heat-related
illnesses in these areas by this weekend.  Meanwhile in the opposite
corner of the country, after a day of drier weather across the Northeast
today, showers and thunderstorms from the Midwest are forecast to reach
into the central and southern Appalachians before slowly edging into
interior New England by Sunday morning ahead of a cold front.

In addition to the heat and the severe storms, Canadian wildfire smoke is
expected to continue impacting portions of the northeastern quadrant of
the U.S. over the next few days.  However, air quality is expected to
slowly improve due to a combination of thunderstorm activity and
dispersion of the smoke as we head into the weekend.

Kong


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