227
ACUS01 KWNS 301630
SWODY1
SPC AC 301629

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Tue Apr 30 2024

Valid 301630Z - 011200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING ACROSS PARTS OF WESTERN IOWA...SOUTHEAST
NEBRASKA...NORTHEAST KANSAS...AND NORTHWEST MISSOURI...

...SUMMARY...
The greatest threat for severe weather (large hail, severe gusts,
and a few tornadoes) is from western and central Iowa to
northeastern Kansas.

...Eastern NE/Western IA/Northwest MO/Northeast KS...
Water vapor loops show a fast-moving shortwave trough and associated
mid/upper level speed max moving across the central Rockies into the
Plains.  Ahead of this trough, southerly low-level winds are
transporting moisture northward with dewpoints in the 60s now as far
north as southeast NE.  Continued daytime heating and moisture
advection will lead to a narrow corridor of moderate CAPE over
eastern NE by mid-afternoon.  A consensus of morning model guidance
indicated that thunderstorms will form in this regime, with other
intense storms developing southward along the surface cold front
into northeast KS by late afternoon.  Forecast soundings show shear
profiles favorable for supercell structures capable of very large
hail and a few tornadoes.  After dark, these storms are expected to
congeal into one or more bowing structures that will track eastward
into central IA/northern MO with a greater risk of damaging wind
gusts along with hail and perhaps tornadoes.

...Eastern KS/Western OK/Northwest TX...
The surface dryline will extend southward from northeast KS into
northwest OK and northwest TX.  Isolated intense storms are expected
from roughly Wichita northward, with decreasing confidence from
there southward.  Weak large scale forcing, rising mid level
heights, and generally warming temperatures at 700mb suggest any
storms that form along the dryline will be widely scattered.
However, large CAPE values, steep mid level lapse rates, and
sufficient vertical shear will support supercell structures capable
of all severe hazards in any storm that can form/sustain.  Will
maintain the ongoing SLGT/MRGL areas at this time, but will
reevaluate at 20z.

...NY/PA...
Strong daytime heating is occurring over areas from central NY into
central PA, where dewpoints are in the upper 50s.  Forecast
soundings suggest afternoon MLCAPE values of 500-1000 J/kg, leading
to scattered afternoon thunderstorms.  Low-level winds are
relatively weak/veered, but sufficient winds aloft and steep
low-level lapse rates could contribute to a risk of gusty/damaging
wind gusts and hail in the strongest cells this afternoon.

..Hart/Lyons.. 04/30/2024

$$