…Debby is forecast to spread excessive rainfall, strong winds and
thunderstorms up through much of the Mid-Atlantic/Central Appalachians and
Northeast through Saturday morning…
…Excessive Heat concerns continue across the Deep South while cooler air
settles over the Central U.S. through the end of the week…
…Monsoonal storms persist over parts of the Southwest, Four Corners and
High Plains…
Tropical Storm Debby is likely to weaken as it moves from the South
Carolina coast and into the Carolina Piedmont tonight before weakening
into a Tropical Depression sometime on Friday while it moves up into the
Central Appalachians of Virginia, Maryland and Pennsylvania. Debby is
expected to produce an additional 4 to 8 inches of rainfall with locally
higher amounts, across portions of southeastern North Carolina leading to
maximum storm total amounts as high as 15 inches. There’s a High Risk (at
least 70%) of Excessive Rainfall leading to Flash Flooding from coastal
North Carolina, into the Piedmont and up through the Blue
Ridge/Appalachians of Virginia. Considerable flooding is expected across
portions of eastern South Carolina and southeast North Carolina through
Friday.
From central North Carolina northward across portions of Virginia, 3 to 7
inches with local amounts to 10 inches, are expected through Friday. This
rainfall will likely result in areas of considerable flash and urban
flooding, with river flooding possible. From portions of Maryland north
through Upstate New York and Vermont, 2 to 4 inches, with local amounts to
6 inches, are expected through Friday night. This will likely result in
areas of considerable flash and urban flooding as well as river flooding.
There’s a Moderate Risk (at least 40%) of Excessive Rainfall over portions
of north-central Virginia up through central Pennsylvania/New York for
Friday as Debby moves up the spine of the Appalachians. Rain, wind and
thunderstorms should come to an end on Saturday when Debby gets swept up
into a powerful upper low propagating across southern Canada.
Elsewhere, a strong cold front associated with the potent upper low in
Canada will drag an anomalously cool airmass down into the mid-section of
the country. High temperatures in the 60s and 70s across the
Northern/Central Plains and Upper/Middle Mississippi Valley will represent
a 15-25 degree negative anomaly for those areas, where some records may be
tied or broken. Strong southerly flow beneath a building mid-level ridge
will support the continuation of a heat wave from Texas into the central
Gulf Coast. Heat Advisories and isolated Excessive Heat Warnings are in
effect for those areas. Conditions should improve a bit this weekend
following the arrival of the cold front.
Monsoonal storms will continue across much of the Southwest, Four Corners
and High Plains over the next few days. Diurnal convection along a stalled
surface front will promote intense afternoon/evening storms capable of
producing heavy rainfall. A Slight Risk (at least 15%) of Excessive
Rainfall today and another on Friday are in effect across portions of the
Front Range of the Rockies and the Sangre De Cristo/San Juan Mountains.
Slot Canyons and burn scars will be most susceptible to flash flooding
from any excessive rainfall that occurs. Wildfires in the Northwest will
contribute to poor air quality over much of Oregon and western Washington
State. Heat Advisories are in effect for western Washington.
Kebede
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
