…Major to locally extreme Heat Risk will expand across the northern High
Plains as heat gradually becomes less intense over the Central Valley of
California and the Great Basin…
…Scattered showers and thunderstorms will extend across the southern
tier states to the East Coast with heavy rain possible along the Texas
coast today…
…A low pressure wave will bring a round of showers and thunderstorms
across the Great Lakes today and across New England on Thursday…
…Monsoonal thunderstorms continue across the Great Basin and into the
Four Corners region with threats of localized flash flooding while fire
weather danger emerges over the interior Northwest…
A slow-to-evolve summertime weather pattern will continue across much of
the U.S. mainland while a more progressive Pacific cold front sweeps
across the northwestern part of the country through the next couple of
days. Under this weather pattern, unsettled weather and relatively cool
temperatures for July will continue across the eastern half of the country
as the ongoing heat wave over the western U.S. gradually becomes less
intense with the arrival of the Pacific cold front. The stronger forcing
associated with this front will push the heat dome east of the Great
Basin, resulting in the expansion of major to locally extreme Heat Risk
across the northern High Plains through the next couple of days. High
temperatures are forecast to reach well up into the 100s to near 110 at
the hottest location over the northern High Plains through Thursday with
little to no rainfall expected. Meanwhile, the heat will gradually become
less intense over the Central Valley of California and the Great Basin
with time. Please continue to practice heat safety as the heat spreads
into the northern High Plains.
By Thursday night into Friday morning, the cold front will make its way
through the northern Rockies into the High Plains will cooler air arriving
but with very little moisture to work with. Meanwhile, lightning
associated with dry thunderstorms triggered by the passage of the cold
front will result in critical fire danger over the interior northwestern
U.S. In addition, monsoonal thunderstorms will continue across the Great
Basin today and become more numerous over the Four Corners region Thursday
into Friday with the threat of localized flash flooding over the next
couple of days.
In contrast to the heat in the West, cooler than normal temperatures will
prevail across the mid-section of the country to portions of the eastern
U.S. where a stalled front will keep plenty of clouds along with scattered
thunderstorms. These thunderstorms are not expected to be severe but they
could result in localized flooding issues from time to time across the
southern tier states as well as up and down the East Coast. A coastal
front interacting with a broad upper-level southwesterly flow could set
off heavy rain and thunderstorms near the Texas coast into southwestern
Louisiana where flash flooding is possible. Therefore, a slight risk of
flash flooding is posted from southeast Texas into portions of the lower
Mississippi Valley while another is in effect from the interior portions
of the Southeast into the Mid-Atlantic farther up along the stationary
front through the next couple of days.
Farther north, a low pressure wave developing along a cold front dipping
into the northern tier states will bring additional thunderstorms across
the Great Lakes today. By Thursday, the Great Lakes should clear out from
the rain but northern New England will see an increasing chance of showers
and thunderstorms as the low pressure wave approaches from the west.
Kong
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php