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 High Plains to the Mid-Atlantic.
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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 today and Friday, with multiple areas under the risk of excessive rainfall and severe thunderstorms each day.
Today, there are Slight Risks of excessive rainfall (level 2/4) for the coastal Carolinas, the Middle-Mississippi/Ohio Valleys, and the Northern 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 today.
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 today.
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 today 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.
Excessive heat is especially dangerous for vulnerable populations.
Be sure to check in on friends and loved ones frequently.
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.
Elevated fire weather concerns continue over the Great Basin through Friday. ■