####018003605####
ACUS02 KWNS 131734

SWODY2

SPC AC 131732



Day 2 Convective Outlook  

NWS Storm Prediction Center Norman OK

1232 PM CDT Sat Apr 13 2024



Valid 141200Z - 151200Z



...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS CENTERED OVER

PARTS OF PENNSYLVANIA...



...SUMMARY...

Scattered severe thunderstorms are possible from late afternoon into

the evening on Sunday, from southwestern Ohio east-northeastward to

southwestern New England. Damaging winds should be the primary

hazard, but a tornado or two and large hail are also possible.



...Synopsis...

A mid-level closed low initially centered over California will move

eastward across the Great Basin Sunday, with downstream ridging to

remain over the Plains/central U.S. through the period.  Farther

east, west-northwesterly flow aloft will prevail, with a belt of

enhanced/70 to 80 kt speeds across the Great Lakes and Northeast

states.  A subtle short-wave trough/vort max associated with the

mid-level jet is forecast to shift across the Upper Ohio

Valley/central Appalachians through the late afternoon/evening

hours.  



At the surface, a weak frontal low initially over the Lower Michigan

vicinity should move quickly eastward to western New England by the

evening.  Meanwhile a trailing, east-west cold front will advance

southward across the southern Great Lakes region and into the

central Appalachians and Midwest States through the afternoon and

evening, and reaching the Mid-Atlantic region and Ohio Valley

overnight.



In the West, a cold front associated with the advancing upper low

will cross the Great Basin and Desert Southwest with time, reaching

the High Plains by Monday morning.



...Upper Ohio Valley area to far southwestern New England...

Steep mid-level lapse rates aloft are forecast to overspread the

northeastern quarter of the country Sunday, as a cold front drops

southward across the Northeast states.  Beneath this

eastward-advecting mid-level lapse rate plume, modest

east-northeastward advection of low-level moisture will occur, with

50s dewpoints expected ahead of the front, from southwestern New

England westward, by late afternoon in a narrow east-to-west

corridor.  This -- combined with diurnal heating across the warm

sector, should yield mixed-layer CAPE values to reach 500 J/kg over

southern New York/eastern Pennsylvania, to 1500 J/kg into western

Pennsylvania and Ohio.  



As the front sags southward and destabilization maximizes through

the afternoon, storm initiation along and just ahead of the front is

expected.  Storms may initially include cellular mode, especially

from central Pennsylvania westward, but flow roughly parallel to the

front should favor quick upscale/linear evolution.  Still, weak

veering and rapid strengthening of the flow with height will support

organized storms -- including rotating updrafts within the line, and

particularly with any storms which can remain at least transiently

cellular.  While the expected linear storm mode should help to limit

tornado potential, a couple of tornadoes are anticipated,

particularly across western and central Pennsylvania, where large

hail may also occur.  Otherwise, the primary severe risk across the

region should be damaging wind gusts, aided by 40 to 50 kt

westerlies extending as low as 900mb per model point-forecast

soundings.



Storms will spread southward into the evening, but should eventually

weaken diurnally as the boundary layer begins to stabilize.



..Goss.. 04/13/2024



$$