…Widespread showers and storms to end the work week across much of the
eastern and southern U.S….
…Threat for scattered flash flooding Thursday for portions of the
Mid-Atlantic and south Texas with a severe weather threat across the
Tennessee Valley/southern Appalachians…
…Conditions remain below average across much of the eastern and southern
U.S. while much above average conditions expand across the north-central
and western U.S….
A broad area of showers and thunderstorms is expected today (Thursday)
ahead of consolidating upper-level waves and an accompanying surface cold
front from the Northeast southwest through the Ohio Valley/Southeast and
westward along the Gulf Coast into southern and western Texas. Moist Gulf
return flow following the dissipation of a broad area of convection
overnight will provide the fuel for moderate to locally heavy rainfall and
isolated flash flooding. A locally higher threat for flash flooding exists
across eastern PA, northwestern NJ, and southern NY, including portions of
the Poconos and Catskills. Storms will have a tendency to move parallel to
the front leading to higher rain totals over already saturated soils, and
a Slight Risk of Excessive Rainfall (level 2/4) in effect. Higher moisture
in an airmass undisturbed by the previous days convection over south Texas
will also lead to widespread storms with a locally higher threat for
heavier downpours and scattered flash flooding, with a Slight Risk in
effect here as well. In addition, a couple areas of severe weather are
expected. First, locally stronger winds associated with one of the
upper-level waves and sufficient instability with warming temperatures
ahead of the cold front will lead to a cluster of strong to severe storms
from the Tennessee Valley east through the southern Appalachians. The
Storm Prediction Center has introduced a Slight Risk of severe weather
(level 2/5) mainly for the threat of very large hail along with damaging
wind gusts. Second, an upper-level shortwave passing over the Rio Grande
Valley/south Texas will bring the threat for some strong to severe storms
here as well, with another Slight Risk in place for additional instances
of large hail and damaging winds. The front will continue eastward into
Friday, with precipitation progressively ending from west to east across
the Ohio Valley/southern Mid-Atlantic southwest through Texas, while
storms continue ahead of the front across the northern Mid-Atlantic/New
England and the Southeast. Moderate to locally heavy rainfall is again
expected with some isolated flash flooding possible, particularly across
central/southern New England and along the central Gulf Coast.
Elsewhere, lingering moisture along the central/southern Rockies and High
Plains will lead to some scattered storms Thursday and Friday. An
upper-level shortwave and accompanying surface frontal system passing from
the northern Rockies/High Plains Thursday to the Upper Midwest Friday will
bring a chance for some isolated showers. Otherwise, much of the Midwest,
Plains, and Great Basin/West Coast will be dry. The consolidating
upper-trough across much of the eastern/southern U.S. while a ridge builds
over the western/northern U.S. will lead to some significant variations in
temperatures the next couple of days. Much of the Great Lakes/Northeast
southwest through the Ohio/Middle Mississippi Valley and central/southern
Plains will see below average highs under the upper-troughing. Highs in
the 50s and 60s will be common for more northern locations with 60s and
70s from the Ohio Valley southwards. Conditions along the East Coast will
be a bit closer to average ahead of the approaching cold front, with highs
in the 60s and 70s for the Mid-Atlantic and 70s and 80s into the
Southeast. In contrast, well above average temperatures will expand in
coverage across the northern Plains/Upper Midwest and Interior West/West
Coast. Forecast highs are generally in the 70s and 80s with 90s in the
central California Valleys and low 100s into the Desert Southwest.
Putnam
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
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