2019 0600 UTC Day 1 Convective Outlook

 ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE LOWER

   OH VALLEY INTO WESTERN TN AND NORTHEAST MS...

   ...SUMMARY...
   Severe thunderstorms capable of tornadoes, large hail, and damaging
   gusts are possible across portions of the Mid South today through
   the early evening.  A strong tornado is possible from the confluence
   of the Ohio and Mississippi Rivers southward into parts of northern
   Mississippi and northwest Alabama.

   ...Synopsis...
   A vigorous, negatively tilted mid-level shortwave trough will move
   from the central/southern Great Plains to the lower MO Valley by mid
   afternoon and subsequently into the Great Lakes after dark.  An
   intense 90kt 500mb speed max will translate east-northeast from OK
   into the lower OH Valley by early evening.  In the low levels, a
   surface low will develop northeast from central KS to the IA/IL/MO
   border by 6pm and into the central Great Lakes overnight.  A warm
   front over the Mid South will advance northward into the lower OH
   Valley by peak heating and a composite dryline/Pacific front will
   arc south-southeast from the low into eastern AR and southwestward
   into east TX by mid afternoon before sweeping east across the OH
   Valley late.

   ...Eastern OK/TX into the mid-MS/lower OH Valleys...
   A complex forecast scenario with associated uncertainty
   appropriately describes the risk for severe thunderstorms and
   possible tornadoes across portions of the Mid South into the lower
   OH Valley today.  At the start of the period, a couple of clusters
   of strong to severe thunderstorms are forecast across western
   portions of the larger-risk area in parts of northeast TX into
   eastern OK/western AR.  Varying possible solutions are evident in
   model data whether all or parts of this activity moves downstream
   with intermittent intensification into the MS Valley during the day
   or whether some of this activity weakens on the southern portion
   near the Ark-La-Tex during the late morning.  Hail, wind, and
   perhaps a tornado or two are possible with the early-day storms over
   the Ark-La-Tex vicinity.

   Farther east, an adequately moist/destabilizing warm sector will
   spread north and northeast in wake of the warm front with surface
   dewpoints ranging from near 60 degrees F in the lower OH Valley to
   the middle 60s farther south into TN/AR/MS/AL.  Model guidance
   correspondingly indicates weaker buoyancy will exist farther north
   (MLCAPEs at or below 500 J/kg north of the OH river to 750-1250 J/kg
   farther south) but extreme low-level shear.  Hodographs become very
   large by early-mid afternoon with flow increasing from 70-90kt in
   the 850-500mb layer over the northern half of the Enhanced Risk
   area.  It seems plausible some attempts at storm development will
   occur during the afternoon near the leading edge of the mid-level
   dry slot.  If the stronger updrafts become sustained, they will
   likely evolve into supercells with tornado potential.  A corridor of
   possibility for supercell tornadoes (perhaps strong) appears
   greatest from the OH/MS confluence southward into northern portions
   of MS on the trailing portion of large-scale ascent moving away from
   the area.  As storms encounter weaker buoyancy farther east and
   northeast during the evening, a transition to linear structures
   capable primarily of damaging winds may occur.

   ..Smith/Squitieri.. 03/09/2019