…Potentially catastrophic flooding associated with Tropical Storm Debby
to impact portions of South and North Carolina…
…Increased flash flood potential for portions of the Desert Southwest
and northern Mid-Atlantic this evening and Wednesday…
…Excessive heat for the Southern Plains to the central Gulf Coast
through Thursday while the Northern Plains…
Tropical Storm Debby is expected to track very slowly northward from its
Tuesday afternoon position near the southern South Carolina coast through
Thursday night, after briefly moving back out over the western Atlantic
ocean tonight. The slow movement will continue to support areas of heavy
rain which are going to fall over the central and eastern Carolinas over
the next 48 hours. Additional rainfall totals of 10-20 inches, with
maximum amounts of 25 inches, are expected which will likely result in
areas of catastrophic flooding. Urban and areal flooding along with major
flooding of area rivers and streams are expected due to the excessive
runoff of heavy rain. In addition, Debby will bring a threat for tornadoes
to coastal sections of the Carolinas through tomorrow, spreading northward
into southeastern Virginia for Thursday. For additional information on
Debby, please visit hurricanes.gov.
Farther north into the norther Mid-Atlantic region, deep moisture related
to Debby along with a slow moving cold front and favorable wind shear
aloft will support the generation of thunderstorms through tonight from
portions of eastern Ohio into the New York City metro region. These
thunderstorms will be capable of severe winds and a couple of tornadoes
along with areas of flash flooding. While the threat for severe
thunderstorms looks diminished on Wednesday for the northern Mid-Atlantic
region, an increased potential for flash flooding will remain from
southern New Jersey into eastern Maryland and the remaining Delmarva
Peninsula.
The aforementioned cold front and reinforcing shots of cooler air from the
north will separate hot and humid conditions over the South from below
average temperatures across the Northern Plains. Locations from the
Southern Plains to the central Gulf Coast will see heat index values
locally over 110 degrees where Heat Advisories are currently in effect.
Little relief in the form of thunderstorms is in the forecast for these
locations. Farther north however, from Montana and Wyoming to the Upper
Mississippi Valley, maximum temperatures are forecast to run 15 to 25
degrees below average on Thursday.
Across the Southwest, an continued active monsoon will favor diurnally
driven thunderstorms capable of short term high rainfall rates, capable of
flash flooding through Thursday. The activity is expected to stretch from
as far west as southeastern California to as far east as the central
Rockies. In the absence of thunderstorm generated cloud cover,
temperatures across the Southwest and much of the western U.S. will
continue to run up to 15 degrees above average beneath the influence of
upper level ridging centered near the Four Corners region.
Otto
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
