SPC Apr 30, 2017 0600 UTC Day 2 Convective Outlook

SPC 0600Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1248 AM CDT Sun Apr 30 2017

Valid 011200Z - 021200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE LOWER GREAT LAKES REGION AND VICINITY...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
GREAT LAKES TO PARTS OF THE SOUTHEAST...

...SUMMARY...
A few strong to severe storms will be possible from parts of the
lower Great Lakes southward to the southeast states on Monday, with
the greatest likelihood across western Pennsylvania and New York.

...Synopsis...
A large mid/upper low will continue lifting northeast across the
Midwest through Monday night, with broad cyclonic flow enveloping
most, if not all, of the contiguous US by the end of the period.
Around the periphery of the closed low, one or more shortwave
troughs will advance northeast from the Ohio Valley/Appalachians
towards the Northeast.

...Lower Great Lakes and vicinity...
While a subtle/weak impulse may cross the region early in the day
(modulated by upstream overnight convection), most of the region is
expected to remain free of precipitation through the early
afternoon. Modest mid-level lapse rates are expected to combine with
weak surface heating and dew points in the lower 60s to produce a
corridor of MLCAPE values around 500-750 J/kg ahead of an
approaching trough/cold front by afternoon. In turn, as convection
along/near this trough approaches western NY/PA and vicinity, it
should intensify some with peak heating. Despite this somewhat
marginal thermodynamic environment, low/mid-level wind fields will
be quite vigorous and veering slightly with height. Therefore,
convection will likely organize into small bands/bowing structures,
with an attendant threat of damaging winds and perhaps a tornado.
Cells will rapidly progress northeast through the afternoon and
evening, before weakening as inhibition increases with eastward
extent.

...Central Appalachians and southward...
While mid-level flow and forcing for ascent will be weaker farther
south, richer low-level moisture (surface dew points in the
mid/upper 60s) will yield more substantive MLCAPE (upwards of 1000
J/kg) by afternoon/early evening. Convection will likely intensify
within pockets of heating amidst remnant cloud cover from overnight
convection to the west. As it does so, effective shear of 30-40 kt
will likely yield at least a few stronger storms, capable of
isolated severe hail and strong/damaging gusts during the afternoon
and evening hours.

..Picca.. 04/30/2017

Read more

from SPC Forecast Products http://ift.tt/GB0aDL