11PM Day 1 Convective Outlook for Friday, January 9. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST TEXAS TO THE CENTRAL GULF STATES
SUMMARY
Severe thunderstorms are expected across southeast Texas into the central Gulf states.
Southeast Texas to Central Gulf States
Midlevel speed max is forecast to translate through the base of the Four Corners trough into southeast NM at the start of the period before advancing into central OK by early evening. Subsequently, this feature will eject into southeast MO by 10/12z in response to a northern stream trough digging into the upper MS Valley overnight.
Late this evening, surface front had progressed to a position from western IL-northern AR-southern OK. This boundary should continue sagging south, and 00z model guidance suggests a weak surface wave will develop along the trailing boundary over south-central TX by early afternoon. Some deepening should occur as a weak surface low advances across northern LA into MS late in the period. Early in the day the primary focus for convection will be along the cold front across the lower OH/TN Valley region into the lower MS Valley, primarily driven by low-level warm advection beneath a modest LLJ. While this early-day convection may pose some risk for damaging gusts and perhaps a tornado, the primary concern will occur later in the day as the secondary speed max ejects across the southern Plains toward southern MO.
Current thinking is elevated thunderstorms should develop ahead of the ejecting speed max/short wave by 18z across south central TX. This initial activity will likely be elevated, but as storms advance downstream surface-based parcels will have negligible inhibition near the lower Sabine River Valley. Hail/wind will be the primary concern early with supercells. During the evening a marked increase in the LLJ is expected across the lower MS Valley into northern AL overnight. As convection advances east, stronger low-level shear will favor some risk for tornadoes. While supercells are expected, a considerable amount of convection is expected along the synoptic warm front, and this should limit northward extent of higher instability air mass.
At this time it does not appear necessary to increase severe probabilities across the lower MS Valley into the central Gulf states, primarily due to the short wave ejecting well north of the higher-instability air mass.