313
ACUS01 KWNS 192001
SWODY1
SPC AC 192000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sun May 19 2024

Valid 192000Z - 201200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
OK...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE PLAINS
AND SOUTHEAST FLORIDA...

...SUMMARY...
Numerous severe thunderstorms capable of widespread damaging winds
and giant hail are expected this afternoon and evening across
portions of Kansas and northern Oklahoma.  Gusts of 75-100 mph are
possible, along with very large hail and a few tornadoes.

...20z Update...
No consequential changes to forecast reasoning and current Day 1
Outlook. Main severe risk as depicted by MDT/ENH risks appears to be
steadily unfolding generally as expected, including intense storm
development along the boundary in north-central Kansas, with
higher-based storms also steadily increasing across southeast
Colorado and the Oklahoma/Texas Panhandles. Semi-discrete supercells
are still expected before cell mergers/aggregating cold pools lead
to potentially significant severe wind potential across
southwest/central Kansas and nearby northern Oklahoma, which is
consistent with latest WoFS forecasts.

..Guyer.. 05/19/2024

.PREV DISCUSSION... /ISSUED 1120 AM CDT Sun May 19 2024/

...KS/OK...
Morning water vapor imagery shows a shortwave trough over northern
AZ.  This feature is expected to accelerate eastward this afternoon,
with an associated mid/upper level jet max nosing into the central
High Plains.  This will lead to scattered high-based thunderstorms
over southeast CO by mid-afternoon, capable of locally gusty winds
and hail.  As this activity builds eastward across the dryline,
rapid intensification of supercell storms is expected.  Forecast
soundings show a relatively deep boundary-layer, but large CAPE
values and dry-adiabatic mid-level lapse rates.  Deep-layer shear
profiles will promote rotating storms capable of very large hail,
damaging winds, and a tornado or two across southwest KS and any
more isolated cells that form southward along the dryline into
western Oklahoma.

As this activity moves eastward, congealing outflows will likely
result in a fast-moving QLCS capable of widespread significant wind
damage for a few hours.  It remains unclear how far east this threat
will persist, but given current model guidance, will not change the
ongoing bounds of the ENH/MDT risk areas in eastern KS.

...Eastern FL...
A surface cold front is sagging southward across the central FL
peninsula today.  Along and ahead of the front, very warm/moist
low-level conditions persist with dewpoints in the low-mid 70s and
strong daytime heating occurring.  It appears likely that at least
scattered thunderstorms will form near/along the east-coast sea
breeze later this afternoon.  Any storm that can intensify before it
moves offshore would potentially acquire supercell characteristics
and pose a risk of large hail and damaging wind gusts.  See
mesoscale discussion #829 for further details.

...SD/NE/Northeast CO...
Strong heating is occurring across much of western SD/NE, where
southerly low-level winds are helping to transport 50s dewpoints in
the region.  A weak shortwave trough currently over WY will approach
the region by mid-afternoon, helping to initiate scattered
thunderstorms from the Black Hills region southward into western NE
and northeast CO.  These storms will be relatively high-based, but
in an environment of sufficient vertical shear to promote organized
multicell or supercell structures capable of damaging winds and
hail.  Storms will persist through much of the evening and spread
into central SD/NE before weakening.

$$