The Nation’s Weather

…Moderate to heavy rain will be moving across the Southwest and Four
Corners today with flash flooding possible…

…Heavy rain, severe weather, and flooding threat develop today over the
north-central Plains, shifting to the south-central Plains and toward the
upper Midwest on Tuesday…

…Tropical moisture is expected to become more focused across South
Florida and then spread northward through the next couple of days…

As an expanding high pressure system settles into the eastern half of the
U.S., unsettled weather will be expanding across the western U.S. toward
the central U.S. through the next couple of days. There are two pieces of
ingredient associated with the unsettled weather in the West. A strong
cold front originating from the Pacific continues to shove the recent
spell of heat in the western U.S. into the mid-section of the country.
Meanwhile, a batch of moderate to heavy rain ahead of an upper-level low
across the Desert Southwest early this Monday morning and is forecast to
overspread the Four Corner and the central/southern Rockies for the
remainder of today. Locally terrain-enhanced rainfall could pose a risk
for flash flooding for these areas. The strong front arriving from the
north will then collide and interact with the moisture arriving from the
central/southern Rockies to produce a around of heavy rain and severe
thunderstorms over the mid-section of the country later today into much of
Tuesday. The heaviest rainfall for today is expected across the
north-central Plains where a low pressure wave is forecast to develop and
track quickly across the region, reaching into the upper Midwest by
Tuesday morning. High temperatures in the lower 90s this afternoon will
be drastically cooler behind the strong cold front under blustery
northerly winds as a high pressure system builds southward from western
Canada. Meanwhile, scattered thunderstorms will also be active farther
south ahead of a dry line where severe thunderstorms are also possible
across the southern High Plains this evening/tonight.

Tuesday will find the strong cold front pushing farther eastward, leading
to the heavy rain, severe weather, and flooding threat shifting into the
south-central Plains and toward the upper Midwest. The trailing portion
of the front will then dip into Texas by Tuesday evening. Thunderstorms
forming ahead of the cold front and the dry line could once again become
strong to severe as the storms march eastward across the Southern Plains
Tuesday night. The dynamics associated with the front are expected to
weaken Tuesday night. This will lead to a gradual lessening threat
of severe weather as the showers and thunderstorms move into the
Great Lakes, Midwest and into eastern Texas by Wednesday morning. The
heavy rains will bring some drought relief to portions of the central U.S.
while additional heavy rains will move across locations in the Southern
Plains and Mid-Mississippi Valley where much above average precipitation
has occurred over the past month. The heavy rain threat across the
Central to Southern Plains will also be accompanied by severe weather
threat, with high winds and large hail the greatest threat but with a
lesser threat for tornadoes.

Across the Sunshine State, tropical moisture in the vicinity of a stalled
front is forecast to linger and gradually become more focused across South
Florida where heavy rain becomes possible by later today. A piece of
upper-level trough diving into the Gulf Coast this morning will begin to
interact with the tropical moisture over Florida. This interaction will
tend to lift the core of the moisture northward, leading to the threat of
heavy rain nudging up the Florida Peninsula on Tuesday into Wednesday
morning, and especially along the east coast of Florida.

Kong/Oravec

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