Valid 231630Z – 241200Z
…THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
WESTERN ARIZONA…
…SUMMARY…
Thunderstorms with very large hail and damaging winds will be
possible today across parts of southwest and central Arizona. Storms
with a few strong wind gusts will be possible in parts of the
Northeast.
…AZ…
Morning water vapor loop shows an intense upper trough digging into
CA/NV. Midlevel height falls, cooling temperatures aloft, and large
scale forcing are overspreading AZ in advance of this system. This
should lead to multiple rounds of thunderstorms today and tonight
over the region. Morning convection and clouds are reinforcing a
baroclinic zone that extends across central AZ. This boundary
should be the focus of thunderstorms though the day, with ample CAPE
and weak CIN over southern AZ. Vertical shear profiles are
sufficient for a few supercell storms capable of very large hail and
damaging wind gusts. An isolated tornado cannot be ruled out.
…Northeast…
A low-amplitude and progressive shortwave trough is moving across
the Great Lakes region today, with an associated cold front
approaching western NY/PA. Widespread clouds are present today
across much of NY into VT, which should limit daytime
heating/destabilization in the area of strongest forcing and
convective potential. This is expected to keep the overall severe
risk in this area MRGL. Have extended the MRGL risk area farther
south in parts of central PA where stronger heating is occurring and
at least isolated afternoon thunderstorms are possible. Despite the
weak instability throughout the risk area, strong winds aloft and
large-scale forcing suggest a risk of gusty/damaging wind gusts in
the strongest storms.
..Hart/Bentley.. 09/23/2019
$$