Mesoscale Discussion 0418
NWS Storm Prediction Center Norman OK
1150 AM CDT Tue Apr 14 2026
Areas affected...Parts of the Northeast
Concerning...Severe potential...Watch possible
Valid 141650Z - 141915Z
Probability of Watch Issuance...60 percent
SUMMARY...The severe risk will gradually increase across the
Northeast through the afternoon. The primary concern will be
damaging wind gusts, though isolated severe hail and some tornado
threat is also possible. While timing is uncertain, a watch may
eventually be needed for parts of the area.
DISCUSSION...Water-vapor and mosaic radar imagery depict a
convectively augmented low-amplitude impulse advancing eastward
across parts of Ontario into Quebec. As this feature continues
eastward, an accompanying weak surface cyclone/frontal wave will
evolve eastward along an east/west-oriented quasi-stationary front
extending across northern NY/VT/NH this afternoon. Preceding the
midlevel impulse and frontal wave, widely scattered thunderstorms
should continue spreading/developing eastward across western/central
NY, as well as along the quasi-stationary boundary farther north.
Continued diurnal heating amid upper 50s to near 60 dewpoints and
increasing low-level warm advection will destabilize the downstream
air mass, yielding a gradual increase in thunderstorm coverage and
intensity with eastward extent this afternoon. Despite only weak to
locally moderate surface-based buoyancy, ample deep-layer shear
(around 40 kt of effective shear) will promote a mix of organized
clusters/line segments and a couple supercell structures (especially
initially). The primary risk will be damaging wind gusts, though
isolated severe hail and perhaps some tornado risk will also be
possible (especially with any supercells that evolve). Given fairly
nebulous large-scale forcing for ascent (especially with southward
extent), overall storm coverage (and to some extent intensity) is a
bit uncertain. While substantial cloud coverage farther north along
the quasi-stationary boundary will limit destabilization compared to
areas farther south, enhanced low-level SRH along the boundary will
conditionally support a risk of organized clusters/supercells. Any
storms that can become surface-based here will be capable of
damaging wind gusts and potentially a locally greater tornado risk,
though this is uncertain.
Despite some uncertainty on timing and overall convective evolution,
the overall severe risk will gradually increase from west to east
into this afternoon, and a watch may eventually be needed for parts
of the area.
..Weinman/Gleason.. 04/14/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GYX...BOX...BTV...OKX...ALY...BGM...BUF...
LAT...LON 41577388 41397517 41457582 41767633 42317640 42827628
43317598 43867548 44327462 44567415 44687353 44657255
44447186 44097157 43617159 43227175 42677215 42237271
41577388
MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
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