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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



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