702
ACUS01 KWNS 190550
SWODY1
SPC AC 190548

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Wed Jun 19 2024

Valid 191200Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN HIGH PLAINS REGION...LOWER GREAT LAKES-NEW ENGLAND...AND
OVER SOUTH TEXAS...

...SUMMARY...
Locally strong gusts and marginal hail may occur with storms over
the southern High Plains, with a couple of strong gusts also
possible from the lower Great Lakes region into New England. A brief
tornado or two may occur over parts of southern Texas tonight in
association with Potential Tropical Cyclone 1.

...Discussion...

Dominant East Coast upper ridge is forecast to build west into the
mid MS Valley later today as the primary belt of westerlies retreats
north of the international border. This westward expansion will
encourage the tropical system over the western Gulf basin to move
into northeast Mexico, considerably south of the Rio Grande Valley.

Convection that developed in association with frontal zone Tuesday
afternoon/evening has weakened considerably, but continues along a
corridor from the upper Great Lakes, southwest across IA into the
Oklahoma Panhandle. Latest model guidance suggests this activity
will be ongoing at the beginning of the period, along with
widespread convective debris. While an embedded disturbance or two
may evolve from this activity, it`s not entirely clear how
substantial subsequent development will be given the weak
environmental shear and modest instability. The greatest risk for
robust updrafts will be across the southern High Plains into
southern NM where strong boundary-layer heating and orographic
influences will be favorable for a few strong to potentially severe
thunderstorms.

Another region where a few strong storms are possible is across the
lower Great Lakes into New England. While upper ridging will
dominate this region, scattered convection will once again develop
from portions of the Ohio Valley, northeast into New England as
surface temperatures warm through the mid 80s to near 90F.
Convective temperatures will be breached and thunderstorms should
develop within a seasonally moist environment with PW values in
excess of 1.75 inches. Gusty winds are the primary concern with this
weakly sheared convection.

Low-level shear will increase markedly during the latter half of the
period across south Texas along the northern fringe of the western
Gulf basin tropical system. This feature may evolve into a tropical
cyclone before it moves inland well south of the lower Rio Grande
Valley. While this system will remain at low latitudes, 850mb flow
is expected to increase across south TX such that sustained updrafts
will likely rotate. High PW and strong low-level shear favors some
low risk for a tornado or two, especially during the latter half of
the period.

..Darrow/Thornton.. 06/19/2024

$$