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000
ACUS01 KWNS 091221
SWODY1
SPC AC 091220

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0720 AM CDT Tue Apr 09 2024

Valid 091300Z - 101200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR CENTRAL
INTO EAST TEXAS AND WESTERN LOUISIANA...

...SUMMARY...
Scattered severe thunderstorms are likely today across much of Texas
into the lower Mississippi River Valley.  Several tornadoes, a
couple of which may be strong, large to very large hail, and severe
gusts are forecast.

...Synopsis...
A mid- to upper-level low evident in water-vapor imagery near the
NM/AZ/Mexico border this morning, will move east into northwest TX
by daybreak Wednesday.  Early morning analysis indicates an
outflow-reinforced effective frontal zone is draped east to west
from western LA into central TX, with the western portion of the
boundary intersecting a surface low over the Permian Basin this
morning.  This surface low will gradually develop eastward into the
TX Hill Country by early evening as the mid- to upper-level
trough/low encroaches on the southern Great Plains.  Little overall
northward advancement is forecast in the outflow/effective frontal
zone across central TX eastward into north-central LA during the
period.

...TX to Lower MS Valley...
A multi-scenario severe thunderstorm outlook is lending considerable
uncertainty to this forecast.  Strong to locally severe
thunderstorms may continue to develop and increase in coverage over
northwest/west TX this morning as the leading edge of stronger upper
forcing for ascent overspreads a capped but moist/unstable airmass
near/north of the frontal zone (reference 12z Midland raob).  As an
80-kt 500mb speed max translates through the base of the upper
trough, additional storm development will likely occur in a
moist/warm conveyor across portions of central TX eastward into
western LA.  Models maintain the LLJ across east TX into southern AR
most of the period.  As a result, episodic bouts of deep convection
should be noted across this region.  Strong boundary-layer heating
on the southwestern periphery of active convective clusters (most
likely to occur over east-central TX and locales farther east) will
yield a very unstable airmass by mid afternoon.  The presence of
surface dewpoints near 70 deg F beneath steep 700-500 mb lapse rates
will yield large buoyancy, and the risk for large to very large hail
with the stronger updrafts.  Large low-level hodographs (200-300
m2/s2 0-1 km SRH) in the warm frontal zone will act to enhance both
supercell development and a tornado risk with any supercells that
can develop and move into this moist/strong low-level shear
corridor.  During the evening, large-scale height falls will spread
east and it seems increasingly probable a squall line will develop.
A few tornadoes and 60-80 mph gusts are possible with this potential
linear MCS.

...Lower Great Lakes...
Southern influence of a strong short-wave trough will glance
northern OH into western NY. Boundary-layer heating is expected to
contribute to modest instability by mid afternoon as surface
temperatures warm through the mid 60s to near 70F. Ample deep-layer
shear will exist for a few robust storms capable of generating gusty
winds and perhaps isolated severe hail. Greatest risk will be with
convection that develops along the front as it eases southeast into
this region.

..Smith/Mosier.. 04/09/2024

$$