940
ACUS01 KWNS 170537
SWODY1
SPC AC 170535

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1235 AM CDT Wed Jul 17 2024

Valid 171200Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE MID-ATLANTIC AND NORTHEAST STATES...

...SUMMARY...
Isolated strong to severe thunderstorms are possible from the
Carolinas into New England on Wednesday, with a corridor of greater
coverage from northeast Virginia into the Hudson Valley and adjacent
southern Vermont/New Hampshire, and western Massachusetts. Isolated
strong to severe thunderstorms are possible across the central High
Plains, and northeast Texas into southwest Arkansas as well.

...Mid-Atlantic and Northeast...

An upper trough over the upper Great Lakes will pivot east toward
the Appalachians today and tonight. A lead shortwave impulse is
forecast to move across the northern Mid-Atlantic and New England
ahead of the main wave during the afternoon/evening. A belt of
enhanced southwesterly mid/upper flow will accompany this feature,
though shear will decrease with southward extent across the
Mid-Atlantic.

At the surface, a cold front develop east/southeast across the
Midwest and northern/central Appalachians during the afternoon and
evening, and reaching the Mid-Atlantic coast Thursday morning. A
very moist airmass will be in place ahead of the front, especially
east of the Blue Ridge toward southern New England. Strong heating
of this moist airmass will aid in moderate to strong destabilization
despite poor midlevel lapse rates. Around 25-30 kt effective shear
magnitudes should support organized bands of storms capable of
damaging gusts. Should sufficient cold-pool development or linear
organized along consolidating outflow occur, a bowing MCS is
possible. However, more favorable shear is expected to be somewhat
displaced from stronger instability, and confidence is too low to
introduce higher wind probabilities at this time.

...Central High Plains...

Modest boundary-layer moisture will spread west into southeast
WY/eastern CO/northeast NM in a post-frontal upslope flow regime
late this afternoon and evening. Meanwhile, the upper ridge will
intensify over the West, and northwest flow aloft will be rather
weak. Nevertheless, steep low-level lapse rates and modest effective
shear magnitudes, given vertically veering wind profiles, will
support widely scattered strong to severe thunderstorms capable of
strong outflow wind gusts. Any longer-lived cells may also produce
marginally severe hail.

...Northeast TX/Southeast OK into southwest AR...

Forecast guidance suggests outflow from prior convection, along with
a southward-sagging surface cold front will support a corridor of
strong differential heating across the region. A very moist airmass
will be in place, aiding in moderate to strong destabilization, and
robust thunderstorm updrafts during the afternoon/evening. However,
vertical shear will be weak, limiting a better organized severe
risk. Nevertheless, isolated strong to severe thunderstorms appear
possible.

...Mid-South into the Southeast...

A seasonally moist and strongly unstable airmass will be in place
across the region ahead of the southward-sagging cold front.
Thunderstorm activity is likely to be numerous, though poor lapse
rates and very weak shear will limit organized severe potential.
However, sporadic strong gusts will be possible given strong
instability and a high PW environment.

..Leitman/Moore.. 07/17/2024

$$