522
ACUS03 KWNS 290727
SWODY3
SPC AC 290726

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0226 AM CDT Wed May 29 2024

Valid 311200Z - 011200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FRIDAY INTO FRIDAY
EVENING ACROSS PARTS OF SOUTHERN OKLAHOMA AND MUCH OF NORTH TEXAS
THROUGH THE UPPER TEXAS COASTAL PLAIN...WESTERN LOUISIANA AND
SOUTHWESTERN ARKANSAS...

...SUMMARY...
One or two organized clusters of storms may evolve by Friday morning
into afternoon and pose a risk for severe wind and hail continuing
across parts of the southern Great Plains into lower Mississippi
Valley and Texas Gulf coast by Friday evening.

...Synopsis...
Downstream of a lower/mid-tropospheric cyclone forecast to elongate
eastward from the northern Canadian Prairies toward western Hudson
Bay, it appears that initially prominent mid-level ridging will
become suppressed southeastward across Quebec and the lower Great
Lakes region.  Farther east, amplified mid-level troughing may
slowly shift east of the Atlantic Seaboard, but models indicate that
a seasonably dry/stable air mass will be maintained across most
areas east of the Mississippi Valley through this period.  Another
surge of cooler and drier air may continue to slowly spread through
the upper Mississippi Valley, mid Missouri Valley and central Great
Plains.

In the southern mid-latitudes, generally weak zonal flow will
prevail to the north of suppressed mid/upper ridging across the
subtropics.  This regime will include at least a couple of
low-amplitude waves and perhaps one or two convectively generated
perturbations.

...South Central U.S...
The 29/00Z NAM, in particular, is suggestive of the development of a
significant convective perturbation across and north of the Red
River Valley vicinity by 12Z Friday.  This may include the evolution
of a prominent mesoscale convective vortex, which may be preceded by
weakening convection, but trailed by strengthening warm advection
driven thunderstorm activity near/northwest of the Wichita Falls
vicinity.  The NAM then suggests the renewed convective development
will undergo significant ensuing intensification and organization,
with another developing mesoscale convective vortex and intensifying
rear inflow (including to in excess of 60-70+ kt in the 850-700 mb
layer) through Friday afternoon across much of North Texas.

Other model output is considerably more vague, or displaced, with
this potential (e.g., a less dramatic convective signal is evident
in the 29/00Z ECMWF, farther to the south across central Texas
toward middle Texas coastal areas).  While there is considerable
uncertainty due to these differences, it appears that the
environment will be potentially conducive to this type evolution, as
a seasonably moist boundary-layer becomes characterized by large
CAPE (2000-4000 J/kg), beneath steep lapse rates associated with an
eastward advecting plume of elevated mixed-layer air.

If/when it becomes clearer that sub-synoptic developments will
evolve anywhere close to what the NAM suggests, severe probabilities
may need to be increased in later outlooks for this period.

..Kerr.. 05/29/2024

$$