Severe Storm Outlook Narrative (AC)
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000
ACUS03 KWNS 220711
SWODY3
SPC AC 220710

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0210 AM CDT Sun Oct 22 2017

Valid 241200Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TUESDAY
AFTERNOON AND EVENING ACROSS PARTS OF THE NORTHERN MID ATLANTIC
COAST REGION INTO WESTERN PORTIONS OF NEW ENGLAND...

...SUMMARY...
Thunderstorms may impact parts of the Northeast on Tuesday,
accompanied by at least some risk for potentially damaging wind
gusts.

...Synopsis...
While another short wave trough progresses inland across the
Canadian Rockies, around the crest of broad upper ridging extending
across the eastern Pacific through much of western North America,
models indicate that large-scale troughing east of Mississippi
Valley may amplify further through this period.  Encompassing much
of the eastern U.S., this troughing may take on more of a negative
tilt as it approaches the Atlantic Seaboard Tuesday through Tuesday
night.  An associated surface cold front is still expected to
precede the upper trough, with one shallower portion surging across
much of the remainder of the Southeast, into the Florida Peninsula,
by early Tuesday afternoon.  Farther north, the front may not
advance into the northern Mid Atlantic coast and Hudson/Champlain
Valleys until late Tuesday afternoon or evening.  Of particular
concern to severe weather potential, is the possibility of rather
strong lower/mid tropospheric wind fields (up to 50-70+ kt in the
850-500 mb layer) within a corridor ahead of the northern portion of
the front.

...Northeast...
Prospects for more than very weak boundary layer destabilization
appear rather slim within the pre-frontal corridor with strongest
mean lower/mid tropospheric winds, from portions of the northern Mid
Atlantic Coast region into western New England, during the day
Tuesday into Tuesday evening.  And relatively warm mid/upper levels
may preclude, or at least limit, the potential for thermodynamic
profiles to support lightning.  However, given the potential
strength of the wind fields off the surface, the development of even
relatively weak/low-topped convection may aid the downward transfer
of higher momentum, contributing to the potential for at least
localized wind damage.

..Kerr.. 10/22/2017

$$



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