11PM Day 1 Convective Outlook for Thursday, February 19. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN MISSOURI ACROSS MUCH OF ILLINOIS INDIANA KENTUCKY OHIO
SUMMARY
Severe thunderstorms, with potential for a couple tornadoes, large hail and damaging wind gusts are possible across parts of the middle Mississippi to lower Ohio Valleys today. Storms may produce strong gusts over parts of coastal central California this morning.
Mid MS Valley / Midwest / OH Valley
Strong southwest flow aloft will stretch from AZ/NM across OK/TX and into the mid MS Valley and OH Valleys. As a trough begins to amplify across the central Plains, significant warming aloft will occur in the midlevels, which may impact quality of instability over the Midwest. However, low-level moisture will already be in place with 50s F dewpoints common and perhaps lower 60s F toward the lower OH Valley, which will initially support favorable instability profiles between 12-18Z today, before the stronger warming aloft occurs.
Low pressure will deepen into MO during the day and move into lower MI by 12Z Friday. A 40 kt low-level jet beneath strong midlevel winds will result in long hodographs, and, 200-300 m2/s2 SRH over much of the warm sector including eastern MO, IL, IN, KY, and OH. Strong heating over MO will result in steep lapse rates and storms are likely to form there near 12-15Z. This activity should generally spread northeastward during the day across IL and IN, perhaps extending into western KY. A couple supercells appear likely, with tornado/hail/wind potential. Behind this initial/midday activity, the rapid warming aloft may reduce potential for additional storms. However, elevated instability should support storms producing hail farther northeast in the warm advection regime across the upper OH Valley and perhaps approaching Lake Erie.
Central CA Coast
A line of shallow convection is forecast to be ongoing close to Monterey County at 12Z this morning, and this activity will translate southward along the coast through 15-18Z. Forecast soundings indicate shallow SBCAPE of 100-200 J/kg, along with moderate mean boundary-layer winds just off the surface. As such, locally strong to damaging gusts cannot be ruled out as the front pushes south.