527
ACUS01 KWNS 261954
SWODY1
SPC AC 261952

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 PM CDT Wed Jun 26 2024

Valid 262000Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE OHIO
VALLEY TO THE NORTHERN MID-ATLANTIC...FROM THE ARKLATEX TO THE LOWER
MISSISSIPPI VALLEY...AND ACROSS THE CENTRAL HIGH PLAINS...

...SUMMARY...
Clusters of thunderstorms accompanied by potentially damaging wind
gusts are possible into tonight from the Ohio Valley into the
northern Mid Atlantic, parts of the Ozark Plateau into the lower
Mississippi Valley, and to the lee of the Front Range and Sangre de
Cristo Mountains.

...20z Update...

Severe probabilities have been trimmed behind ongoing convection
from the Ozarks into northern IN/OH and parts of PA/NY. Meanwhile,
the Marginal (level 1 of 5) and Slight (level 2 of 5) has been
expanded across southeast TX, southwest LA, and parts of MS/AL ahead
of a south and eastward advancing band of storms. A very moist, hot
and unstable, but weakly sheared airmass may allow sporadic damaging
gusts to persist into early evening to the south and east of WW 465.


Severe thunderstorm potential will continue across WW 464 over parts
of PA/southern NY, with some increase in severe potential developing
over the next couple hours to the south and east of this watch.
Reference forthcoming MCD 1429 for info on short term severe
concerns across the Mid-Atlantic vicinity.

The only other change to severe probabilities with the 20z update
was to add 5 percent hail probabilities across ID/MT/far northwest
WY. Vertical shear is sufficient for organized cells. Cool
temperatures aloft and modest instability amid straight/elongated
hodographs will support isolated hail potential in addition to
sporadic strong gusts. See MCD 1428 for more information.

No changes were made to the central High Plains Slight (level 2 of
5) risk area. Convection is expected to increase in
coverage/intensity over the next few hours. Isolated severe gusts
and hail remain possible through evening.

..Leitman.. 06/26/2024

.PREV DISCUSSION... /ISSUED 1119 AM CDT Wed Jun 26 2024/

...NY/PA into Mid Atlantic and southern New England...
Morning water vapor imagery shows a fast-moving trough over WI.
This feature will track across the Great Lakes region today and into
the northeast states tonight.  Ahead of the system, strong heating
is occurring from parts of NY/PA eastward into the Mid Atlantic
region and southern New England.  A diffuse surface boundary extends
from northern PA to coastal New England, with temperatures likely to
rise into the 80s/90s to the south.  This will result in an
environment of steep low-level lapse rates and sufficient CAPE for
scattered afternoon thunderstorms.  Current indications are that
storms will form over OH/western PA by early afternoon and spread
eastward through the day.  Damaging winds appear to be the main
concern.  Storms may track across southern New England and to the
NJ/DE/MD coast during the evening with a continued severe threat.

...High Plains...
A plume of considerable mid-level moisture is present today over the
central Rockies.  This will lead to scattered thunderstorms over the
higher terrain by mid afternoon, spreading eastward into the
adjacent plains.  Easterly low-level winds over the plains will
maintain 40s/50s dewpoints and pose a risk of a few severe storms
capable of hail and gusty/damaging winds this evening.

...ArklaTex into TN...
A weakening linear MCS currently extends from northeast TX into
northeast AR.  The air mass ahead of this activity is very
moist/unstable, with dewpoints in the mid 70s and afternoon MLCAPE
values likely 2000-2500 J/kg.  Winds aloft are rather weak, but will
maintain ongoing SLGT area in case these storms rejuvenate.

$$