ACUS01 KWNS 181959

SWODY1

SPC AC 181958



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0258 PM CDT Thu Jun 18 2026



Valid 182000Z - 191200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF

WESTERN NORTH TEXAS...THE SOUTHEAST AND CAROLINAS...INTO NEW

ENGLAND...



...SUMMARY...

Isolated to scattered severe thunderstorms remain likely from

Kentucky and the central Appalachians to the Mid-Atlantic, with

primarily damaging wind gusts or marginal hail. Scattered severe

storms are possible from upstate New York into New England, with

damaging wind gusts and tornado potential. A few tornadoes may also

occur over parts of the middle Gulf Coast and southeast states, and

scattered storms may produce damaging winds or marginal hail from

Oklahoma into western North Texas.



...20z Update TX/OK...

Forecast confidence has increased late this afternoon into tonight

that one or more semi-organized clusters of thunderstorms will

develop and spread southeastward across parts of western North TX

with a risk for damaging gusts. Strong convergence near an

anomalously deep surface low and sagging cold front will support

numerous thunderstorms tonight. Despite marginal deep-layer shear

for organization, a hot and very unstable air

mass in vicinity of the surface low will allow for strong cold pool

development, potentially supporting severe outflow gusts. More

isolated damaging gusts and/or marginally severe hail remain

possible farther north into OK. Have upgraded wind probabilities to

15% and a categorical Level 2 Slight Risk for portions of western

North TX.



...Southeast...

Convection associated with the remnants of Arthur will persist

through tonight along a stalled frontal zone in the Southeast. While

clustering has resulted in more linear structures, enhanced flow

aloft and pockets of stronger low-level shear near the front may

still support occasional rotating updrafts, with the risk for a

couple of tornadoes or damaging gusts from eastern AL, into GA and

the western Carolinas through tonight. Have reduced maximum tornado

probabilities, but will maintain a broad 5% for occasional supercell

structures along/near the front.



...New England...

The broken band of storms ahead of the cold front should continue

eastward and gradually weaken into this evening. Southern portions

of the line over MA, CT and RI may remain stronger given better

buoyancy, but storm coverage here should become more isolated with

time. Damaging gusts and perhaps a tornado or two remain possible.

Have trimmed probabilities behind the cold front where the risk has

decreased. No other changes were made, see the previous discussion

for more information.



..Lyons.. 06/18/2026



.PREV DISCUSSION... /ISSUED 1116 AM CDT Thu Jun 18 2026/



...NY/New England...

A fast-moving low-topped squall line is tracking eastward across NY.

Low and mid level wind fields in this region are very strong,

contributing to occasional bowing structures and QLCS mesocyclones. 

This activity will spread into VT/NH through the afternoon with a

continued risk of damaging winds and isolated tornadoes.  Confidence

in severe storms farther south into southern New England is lower,

but at least isolated strong/damaging wind gusts are possible.



...KY into Mid Atlantic...

A remnant outflow boundary from overnight storms extends across KY

into southern VA.  Strong heating along and south of the boundary

will likely result in renewed convection this afternoon, in a zone

of moderate westerly flow aloft and CAPE values around 2000 J/kg.  A

few severe storms are expected in this corridor, with activity

moving into northern NC later today.  Damaging winds are the main

risk.



...Gulf Coast into Carolinas...

The remnant circulation of Arthur is becoming more progressive with

time, and is accelerating eastward.  As this occurs, the zone of

relatively strong southerly low-level winds will also shift across

AL into GA and eventually SC/NC tonight.  Ample low-level moisture

and high theta-e values will coincide with the region of strong

shear, and CAM solutions suggest clusters of thunderstorms in this

area as well.  This suggests at least some risk of damaging wind

gusts and tornadoes through the afternoon and night as the system

moves northeastward.



...TX/OK...

Scattered thunderstorms will occasional hail risk will slowly

diminish across northern OK this afternoon.  Later today, new

thunderstorms are expected to develop in a hot and very unstable air

mass in vicinity of the surface low near ABI/SJT.  These slow-moving

storms will have some damaging wind and hail risk through the

evening.



$$