Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 201739
SWOMCD
SPC MCD 201738
MEZ000-NHZ000-VTZ000-NYZ000-201945-

Mesoscale Discussion 1361
NWS Storm Prediction Center Norman OK
1238 PM CDT Thu Jul 20 2017

Areas affected...Much of Vermont...New Hampshire...Maine...and far
northeastern NY

Concerning...Severe potential...Watch unlikely

Valid 201738Z - 201945Z

Probability of Watch Issuance...20 percent

SUMMARY...Widely-scattered to scattered thunderstorms are expected
to increase in coverage the next few hours and will pose a threat
for brief severe wind gusts, but the isolated nature of the threat
is expected to preclude the need for a Watch.

DISCUSSION...Visible satellite imagery shows an expansive cumulus
field over the area with a few thunderstorms along the western edge
of this field over far northern Maine and far northwestern Vermont.
A 100-kt westerly upper level speed max currently overspreading NY
is contributing to forcing for ascent and is increasing the bulk 0-6
km vertical wind shear to 30-45 kt, supportive of some organized
convective structures.  However, weak wind shear in low-levels, and
substantial dryness in mid-upper levels, also characterized by poor
lapse rates, should limit the severe potential.  Nonetheless, steep
low-level lapse rates in regions that experience the strongest
heating could support brief severe wind gusts with the strongest
downdrafts.  This threat should remain isolated enough to preclude
the need for a Watch.

..Coniglio/Cohen/Hart.. 07/20/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CAR...GYX...BTV...

LAT...LON   47226941 47266847 47026806 46366794 45576812 44606885
            44076982 43807061 43547124 43407175 43407261 43687288
            44167320 44707342 45077339 45567272 45887197 46267119
            47226941




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