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ACUS01 KWNS 121627

SWODY1

SPC AC 121626



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

1126 AM CDT Fri Apr 12 2024



Valid 121630Z - 131200Z



...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS

OF EASTERN NEW YORK/WESTERN NEW ENGLAND...AND FROM NORTHERN NEVADA

TO WESTERN MONTANA...



...SUMMARY...

Isolated severe wind gusts and hail may occur with thunderstorms

over northern Nevada, eastern Oregon, Idaho, and far western Montana

late this afternoon and early evening.



...Champlain/Hudson Valleys of New York into western New England...

Showers appear to be increasing at this time across the

Hudson/Champlain Valleys, ahead of an occluded front moving eastward

across eastern portions of Upstate New York early this afternoon.  A

lobe of vorticity will continue rotating northeastward across the

region this afternoon, on the eastern fringe of the upper low

crossing the Great Lakes.  Cold air aloft combined with weak

insolation through breaks in the cloud cover evident in visible

satellite imagery will permit additional/modest destabilization.  As

a result, low-topped thunderstorms are expected to develop across

this area.



With deep-layer flow somewhat unidirectional/meridional, but

strengthening with height, shear will support organized storms and

potentially a few rotating updrafts.  As a result, a brief/weak

tornado or two will be possible, along with gusty winds that may

approach severe levels locally, with a few stronger cells and/or

line segments.  As such, a MRGL risk is being introduced across a

portion of eastern New York and into parts of western New England. 

For additional short-term information, please refer to SWOMCD #429.



...Parts of northern Nevada to western Montana...

Ahead of the advancing upper low, daytime heating beneath steep

mid-level lapse rates will result in modest destabilization, with

degree of CAPE hindered due to scant moisture availability across

this region.  Still, with a few hundred J/kg mixed-layer CAPE likely

by late afternoon, widely scattered thunderstorms are expected to

develop.



With favorably strong flow aloft across this area, a few

stronger/sustained updrafts appear likely.  With a very deep

well-mixed boundary layer expected across the region, gusty

downdraft winds -- enhanced due to evaporative cooling in the

sub-cloud layer -- may reach severe levels in a few instances.  This

warrants continuation of the MRGL risk across into early evening.



...Ohio Valley to the Mid-Atlantic region...

Scattered showers should diurnally increase from parts of the OH

Valley across the central Appalachians to the Virginia/North

Carolina area, with eventual/embedded low-topped thunderstorms

expected to develop within the broader area of precipitation this

afternoon.



The convection will be associated with cold mid-level temperatures

accompanying a shortwave trough, that is embedded within the broader

cyclonic circulation across the eastern CONUS. With generally

west-northwesterly flow behind the cold front, instability should

remain very weak.  Still, enhanced low-level winds may reach the

surface given the anticipated well-mixed boundary layer, resulting

in occasional strong/gusty winds with a few of the stronger

convective elements.



..Goss/Bentley.. 04/12/2024



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