Severe Storm Outlook Narrative (AC)
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180
ACUS11 KWNS 231803
SWOMCD
SPC MCD 231802
MEZ000-MAZ000-NHZ000-VTZ000-NYZ000-232030-

Mesoscale Discussion 1134
NWS Storm Prediction Center Norman OK
0102 PM CDT Fri Jun 23 2017

Areas affected...Portions of NY...VT...NH...ME...and MA

Concerning...Severe potential...Watch unlikely

Valid 231802Z - 232030Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated strong to damaging winds and perhaps some hail
may occur with strong to severe thunderstorms through the early
evening. The overall severe weather threat will probably remain too
marginal to warrant watch issuance, although radar trends will
continue to be monitored.

DISCUSSION...Around 40-55 kt of mid-level southwesterly flow is
present this afternoon across much of New England and vicinity as
large-scale upper troughing approaches this region from the west.
Breaks in the cloud cover have allowed surface temperatures to
generally warm into the upper 70s to mid 80s away from the coast,
and a moist low-level airmass is present, with surface dewpoints in
the mid 60s to around 70. A warm front at the surface is located
from southern Quebec across NH and western ME as of 18Z, and this
front should make some northward progress into central/eastern ME
through the remainder of the afternoon. Although mid-level lapse
rates remain generally poor across this region per 12Z soundings
from GYX/ALB, 250-1000 J/kg of MLCAPE is present as of 18Z owing to
the previously mentioned diurnal heating and moist low-level
airmass.

A veering/strengthening wind profile with height will support 35-45
kt of effective bulk shear, which should encourage some updraft
organization. Steep low-level lapse rates and a well mixed boundary
layer will encourage efficient momentum transfer of stronger
thunderstorm downdraft winds to the surface, and locally damaging
surface winds appear to be the main threat with this activity. Some
hail may also occur, but poor mid-level lapse rates will likely
limit a more substantial severe hail threat. Present indications are
for the overall severe threat to remain isolated through peak
heating, which suggests watch issuance will probably not be needed.

..Gleason/Guyer.. 06/23/2017

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

ATTN...WFO...GYX...BOX...BTV...ALY...BGM...BUF...

LAT...LON   43447825 43717792 43647681 44177637 44567588 45107490
            45107168 45347154 45477102 45607066 45577013 45196977
            44037053 43347073 42647053 42277081 42147137 42077283
            42087419 42567612 42647844 43447825




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