Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 151903
SPC MCD 151903

Mesoscale Discussion 1719
NWS Storm Prediction Center Norman OK
0203 PM CDT Sun Oct 15 2017

Areas affected...From eastern Ohio across Pennsylvania and into
western/central New York

Concerning...Severe potential...Watch possible

Valid 151903Z - 152000Z

Probability of Watch Issuance...40 percent

SUMMARY...A narrow line of low-topped showers and thunderstorms will
develop eastward with a threat of strong to severe wind gusts this

DISCUSSION...Multiple segments of low-topped showers and storms are
developing from southwest Ontario into eastern Ohio along an
intensifying cold front. The strongest area of lift currently exists
over Canada, and this is where sporadic lightning activity is

Surface observations show gradually warming temperatures, with
dewpoints in the lower 60s. The deeper moist plume exists mainly
just ahead of the front, with drier air/lower PW values from the
Appalachians into New England. Temperatures aloft are not very cold
except for well behind the front into Michigan, leading to only weak
CAPE values. In addition, much of the instability exists mainly in
the parts of the atmosphere.

With mean winds in excess of 40 kt in the lowest few km, these
showers and storms along the cold front will likely transfer
momentum to the surface with 40-50 mph wind gusts possible, and
perhaps an isolated severe gust. The most likely area for severe
winds would appear to be over New York where mean wind speeds are
strongest, and in closest proximity to the shortwave trough. In
addition, veering winds with height and sufficient SRH may result in
embedded areas of rotation in QLCS fashion. This, however, will be
dependent on sufficient instability being present. Ample heating
over NY lends some confidence of this possibility.

..Jewell/Hart.. 10/15/2017

...Please see for graphic product...


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            40338016 40308120 40628143 41138132 41808085 42798018
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