000
ACUS01 KWNS 271609
SWODY1
SPC AC 271608

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1108 AM CDT Tue Jul 27 2021

Valid 271630Z - 281200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
OVER PARTS OF NEW YORK AND NEW ENGLAND...AND THIS EVENING OVER PARTS
OF MINNESOTA...WISCONSIN...AND IOWA....

...SUMMARY...
Severe thunderstorms are possible today from western New York across
parts of New England, and mainly tonight over portions of the upper
Mississippi Valley region.

...NY into New England...
A long-lived MCV that affected MN last evening is now over southeast
Ontario.  A line of thunderstorms associated with the MCV is moving
into western NY at over 45 knots.  The air mass ahead of the
activity is warming rapidly, with dewpoints in the low/mid 60s
leading to afternoon MLCAPE values of 1000-1500 J/kg.  This will
result in intensification of the storms this afternoon over NY with
an increasing risk of damaging winds.  Storms are likely persist
into central New England later this afternoon and evening before
weakening.

There is also some potential for re-development of storms over
western NY and northern PA later today, but confidence of this
scenario is lower.

...MN/WI/IA...
A surface baroclinic zone is forecast to strengthen this afternoon
over MN/WI, with hot/humid conditions over southern MN and northerly
winds developing over northern WI.  Increasing convergence along the
boundary will lead to at least isolated thunderstorm development
late this afternoon or evening.  Sufficient deep-layer shear will
promote supercell storm structures capable of large hail.  Storms
may congeal during the evening with an increasing risk of damaging
wind gusts over southern WI.

..Hart/Wendt.. 07/27/2021

$$