…Slow-moving thunderstorms will lead to additional heavy downpours and
the threat for flash flooding over saturated grounds in central Texas…
…Tropical Storm Chantal is forecast to make landfall in the Carolinas
early Sunday bringing heavy rain and flash flooding to the coastal plain…
…Scattered showers and thunderstorms will move across the northern
Plains, upper Midwest/Great Lakes followed by strong to severe
thunderstorms across the northern and central High Plains…
…Heat and humidity will shift from the Great Lakes region Saturday to
the South and East Coast the next couple of days, with notable population
centers entering the Major Heat Risk category…
Thunderstorms associated with a remnant small-scale mid-level vortex
responsible for the devastating flooding in central Texas over the past
couple of days continue into this afternoon with multiple ongoing Flash
Flood Warnings. A Slight Risk of Excessive Rainfall (level 2/4) remains in
effect as very anomalously high levels of Gulf moisture contribute to
torrential downpours (multiple inches of rain per hour), which can lead to
scattered, rapidly developing and dangerous instances of flash flooding.
While storms are expected to decrease in coverage into the
evening/overnight hours, some storms may redevelop by as early as Sunday
morning and last into the day Sunday, with a continued risk for flash
flooding mainly for areas that have already been hard hit from the prior
days rainfall. Fortunately, drier weather is expected heading into Monday.
Tropical Storm Chantal, located off the southeast Atlantic coast, is
currently forecast by the National Hurricane Center to make landfall
between Charleston, SC and Cape Fear, NC, early Sunday morning. However,
tropical storm conditions can be expected throughout this vicinity
beginning early this evening and continuing through Sunday morning. Bands
of thunderstorms producing heavy rainfall totals of 2-4 inches, locally
upwards of 6″, may lead to scattered instances of flash flooding, with a
Slight Risk of Excessive Rainfall (level 2/4) covering coastal areas
through Sunday morning and further inland across the coastal plain through
Monday morning. Showers will decrease into Monday but some isolated heavy
downpours and instances of flash flooding are expected from the Carolina
coastal plain northward into the southern Mid-Atlantic. In addition to
flash flooding, life-threatening surf and rip currents are expected along
the Atlantic coast from Florida northward to the Mid-Atlantic states over
the next couple of days.
Scattered showers and thunderstorms are expected broadly across portions
of the eastern and central U.S. ahead of a slow moving cold front the next
couple of days. The focus through Saturday evening will be across portions
of the Upper Midwest southwest to the Missouri Valley with some isolated
heavy downpours and instances of flash flooding possible. The front will
continue southeastward on Sunday, bringing storm chances to the Lower
Great Lakes southwest through the Middle Mississippi Valley, and then into
the interior Northeast southwest through the Ohio Valley Monday, with some
additional heavy downpours and isolated flash flooding expected. Further
west, storms are also expected in moist upslope flow along the High
Plains. For Saturday evening, storms are expected across the central and
especially northern High Plains with some severe weather. There is an
Enhanced Risk from the Storm Prediction Center (level 3/5) for the threat
of very large hail and significant damaging winds. The storm focus shifts
southward into the central High Plains and adjacent central Plains Sunday
and Monday, with Slight Risks both days for a continued threat of very
large hail and significant damaging winds. Isolated flash flooding is
possible as well. Additional storms are possible through the southern High
Plains Sunday/Monday, with isolated flash flooding possible. Elsewhere,
daily scattered thunderstorms are forecast along the Florida and central
Gulf Coasts. The West should be mostly dry.
Hot, muggy weather continues today across much of the Great Lakes ahead of
the cold front, with highs into the mid-90s. These conditions are expected
to spread and expand eastward to the East Coast and across the South the
next couple of days, as highs climb into the low to mid-90s with high
humidity levels. Most of the region is under Moderate to Major Heat Risk,
including many of the major population centers, indicating a level of heat
that can impact anyone without adequate access to air conditioning or
hydration, especially those groups more sensitive to heat. Temperatures
are also expected to climb across much the West, particularly for the
interior Pacific Northwest/northern Great Basin and in the Desert
Southwest, after more comfortable, below average conditions to start the
holiday weekend. Temperatures will remain cooler and below average Sunday
across much of the northern tier of the country from the northern Rockies
to the Upper Midwest following a cold front passage, with highs in the
upper 60s to low 80s. Temperatures will be generally seasonable southward
through the Plains with some lingering below average conditions into the
southern Plains given precipitation and cloudiness in the region.
Putnam
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
