spc ac 181913
day 3 convective outlook
nws storm prediction center norman ok
0213 pm cdt mon may 18 2026
valid 201200z - 211200z
...there is a marginal risk of severe thunderstorms across southern
new england into the mid-atlantic and over the southern high plains
into southwest texas...
...summary...
scattered thunderstorm activity across the mid-atlantic region
wednesday may pose a risk for sporadic occurrences of damaging
wind. large hail is expected to be the predominant hazard with
isolated to widely scattered thunderstorms developing over the
southern high plains into southwest texas.
...synopsis...
a short-wave trough and attending mid/upper-level jet streaks will
progress from the great lakes through the st. lawrence valley, with
a modest enhancement to the westerly, mid-level flow as far south as
southern new england and the mid-atlantic region. elsewhere, a
short-wave trough initially near the four corners region will weaken
while moving into confluent, mid-level flow over the central and
southern high plains. at the surface, a cold front will advance
southeast through new england and the mid-atlantic wednesday, with
an upslope regime becoming established over the southern high
plains.
...southern new england into the mid-atlantic...
a moist and moderately unstable air mass is expected to develop
ahead of the front wednesday afternoon, along the immediate southern
fringe of the stronger mid-level flow and resultant deep-layer
shear. the generally weak warm-sector shear and poor mid-level lapse
rates are expected to limit the potential for a more robust
severe-weather threat. however, the presence of steep low-level
lapse rates will support locally strong up/downdrafts capable of
isolated occurrences of damaging winds during the afternoon and
early-evening hours.
...southern high plains into southwest texas...
surface ridging initially over the southern high plains wednesday
morning is forecast to weaken through the day with a narrow wedge of
50s to low 60s boundary-layer dewpoints from the edwards plateau
into southeast nm, to the south of a weakening surface front. the
moisture will combine with steep low/mid-level lapse rates to
support a corridor of moderate, surface-based instability by
afternoon. a broader envelope of moderate, elevated instability is
expected to develop over the southern high plains wednesday
afternoon into night, to the north of the front.
low-level upslope flow into the high terrain of nm and southwest tx
will be augmented by the glancing influence of the short-wave trough
to support isolated to widely scattered thunderstorms during the
afternoon amidst a kinematic environment featuring 30-40 kt of
deep-layer shear. the primary hazard will be sporadic large-hail
occurrences. additional, elevated thunderstorms are expected to
develop wednesday afternoon into evening across the tx south plains
into west-central tx, within a strengthening warm-advection regime.
while deep-layer shear is expected to be weaker than locations to
west/southwest, the presence of steep mid-level lapse rates will
support vigorous updrafts capable of isolated, large hail
occurrences.
..mead.. 05/18/2026
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note: the next day 3 outlook is scheduled by 0730z