…Severe thunderstorms and flash flooding are expected for portions of
the Mid-Atlantic into the Northeast Through Monday…
…Some relief expected for the central Gulf Coast early this week but
dangerous heat and humidity to continue across the Southern Plains…
…Increased risk for spreading of wildfires from central Nevada into
southeastern Oregon through Tuesday…
A slow moving cold front, extending from western New York/Pennsylvania
into the Gulf Coast states, will gradually translate east over the next
one to two days, clearing a majority of the East Coast by Tuesday morning.
Along and ahead of the cold front, anomalous moisture and thunderstorms
repeating over the same locations will pose a threat for flash flooding
with the greatest flash flood concern from the northern Mid-Atlantic into
southern New England this evening and tonight. Severe thunderstorms will
also be possible ahead of the cold front with the greatest risk being
straight line winds, extending from the northern Mid-Atlantic into the
Southeast, Gulf Coast states and portions of the central Plains through
Monday morning. Conditions will improve in the wake of the cold front with
a significant cooling trend for the Midwest and Northeast through Tuesday
with high temperatures forecast to be 10 to 20 degrees below mid-August
averages.
High heat and surface dewpoints will persist across the southern U.S.
beneath the influence of an upper level ridge centered over the southern
High Plains through at least mid-week. Excessive Heat Warnings and Heat
Advisories are already in place from southern Kansas into Oklahoma and
Texas, eastward to the central Gulf Coast. Daytime temperatures combined
with high humidity will result in heat index values ranging from 105 to
locally over 115 degrees for portions of the region. A southward sagging
cold front will bring cooler temperatures into the lower Mississippi
Valley beginning tomorrow and continuing into Tuesday, but the heat will
remain through at least mid-week for Texas, eventually spreading into New
Mexico.
Out West, another slow moving cold front, located over the interior of the
Northwest, will remain nearly stationary until Tuesday. Temperatures from
northern California into Oregon and Washington (west of the boundary) will
experience high temperatures roughly 5 to 15 degrees below average along
with some rain for western Washington. East of the boundary however, hot
temperatures will not be the big concern but rather dry and windy
conditions favoring increased risks for wildfires from central Nevada into
southeastern Oregon and adjacent locations. Due to the slow movement of
the upper pattern, these conditions will remain in place for multiple
days.
The southwestern U.S. will see monsoonal moisture continuing to favor a
risk for short term heavy rain capable of localized to scattered areas of
flash flooding. The flash flood risk will overlap with a risk of severe
thunderstorms from Utah and portions of eastern Idaho and western Wyoming
this evening, with the overlapping risk extending east into east-central
Colorado for Monday. On Tuesday, the threats for severe thunderstorms and
flash flooding appear lower but a localized threat will remain for the
Desert Southwest into portions of Montana ahead of the aforementioned cold
front.
Otto
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
