11AM Day 2 Convective Outlook for Friday, January 23. NO SEVERE THUNDERSTORM AREAS FORECAST
SUMMARY
Scattered weak thunderstorm activity appears possible Friday into Friday night in a corridor across the Texas Big Bend into central Texas.
Discussion
A confluent mid-level regime will generally be maintained across and east of the Rockies through this period, downstream of amplified split flow across the central/eastern Pacific into far western North America. Although models continue to indicate that peak surface pressures within the center of initially prominent, cold surface ridging will begin to fall while it slowly shifts east of the Missouri Valley, appreciable modification of the Arctic air will be slow, and it is likely to continue surging southward across the remainder of the southern Great Plains, through much of south central and southwestern Texas by late Friday night.
The leading edge of this air mass is also forecast to advance further offshore of the southern Mid Atlantic coast, but slower southward through the eastern Gulf Coast states and lower Mississippi Valley. Models indicate that this will occur beneath a broad building mid-level ridge east of the Rio Grande Valley into the Southeast, downstream of digging mid-level troughing across the international border into the northern U.S. Rockies/Great Plains and a short wave trough emerging from the southern mid-latitude eastern Pacific.
There is notable continuing spread concerning the eastward acceleration of the southern perturbation, generally toward Baja, Friday through Friday night. However, an increasingly moist and strengthening downstream southerly return flow still appears probable across and north of the lower Rio Grande Valley and Texas coastal areas, particularly during the latter half of the period.
Southern Great Plains across/northeast of Red River Valley
Forecast soundings and other model output continue to indicate that lower/mid-tropospheric thermal and moisture advection may lead to thermodynamic profiles characterized by at least very weak to weak conditional instability in a sizable swath from the northern Mexican Plateau across the southern Great Plains, including north and northeast of the Red River Valley. However, particularly with north-northeastward extent, above the southward surging cold surface air, these same soundings generally exhibit little in the way of convective instability, with profiles tending to becoming saturated while also warming aloft. So the extent of potential for convective development capable of producing lightning remains unclear Friday through Friday night.
Modestly steeper mid-level lapse rates, and perhaps better potential for weak thunderstorm activity, may remain confined to a corridor across the Texas Big Bend into Edwards Plateau, and adjacent portions of central Texas, where mid/upper support for convective development may be aided by a short wave perturbation emanating from the subtropical eastern Pacific.