SPC AC 161259

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0759 AM CDT Thu Mar 16 2023

   Valid 161300Z - 171200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
   OKLAHOMA/NORTH TEXAS AND FAR SOUTHWEST ARKANSAS...

   ...SUMMARY...
   Scattered severe thunderstorms capable of producing large hail,
   damaging winds, and a few tornadoes are likely this afternoon and
   evening across parts of the southern Plains. Some of the hail could
   be very large over southern Oklahoma and north-central Texas.

   ...Southern/Eastern Oklahoma and Central/North Texas...
   Emerging from split flow over the West, a low-amplitude shortwave
   trough and mid/high-level speed max centered along the Arizona/New
   Mexico/International border vicinity early this morning will
   steadily influence the region into mid/late afternoon. Low-level
   moisture will stream north-northeastward today, with lower 60s F
   surface dewpoints quickly becoming established into southern/eastern
   Oklahoma and the ArkLaTex, and middle 60s F across central/east
   Texas. This will be to the east of a surface trough/dryline, and to
   the southeast of a cold front that will steadily progress
   southeastward and overtake the dryline from north to south through
   tonight.

   Within the warm sector, diurnal heating will promote moderate to
   locally strong destabilization with MLCAPE of 1500-2500 J/kg in the
   presence of relatively steep mid-level lapse rates. Effective shear
   will increase into the 40-60 kt range as strong mid-level flow
   overspreads the region.  

   With the relatively early arrival of strong forcing for ascent and
   cooling aloft reaching the cold frontal vicinity/nearby warm sector,
   strong to severe thunderstorms could develop near the advancing
   front by early afternoon across southwest into central/south-central
   Oklahoma. Subsequent additional development can be expected
   southward into North Texas into late afternoon in vicinity of the
   dry line, some of which could be semi-discrete in advance of the
   upstream cold front. 

   The initial frontal storms and any discrete development across the
   warm sector should quickly evolve into supercells across southern
   Oklahoma and north-central Texas, with a threat of very large hail
   and isolated severe wind gusts. Effective SRH of 200-400 m2/s2 will
   support a tornado threat (including a conditional risk for a strong
   tornado) with any sustained warm-sector supercells that can avoid
   being undercut by the front.

   ...Central/South-Central Texas...
   The potential for pre-frontal storm development is more uncertain
   with southwestward extent into south-central Texas, with this area
   being further removed from the ejecting shortwave trough. However,
   any discrete supercell development along the pre-frontal trough or
   the front itself would quickly pose a threat of large hail and
   isolated severe gusts. Storm coverage will increase with time along
   the front tonight. While there will be a tendency for storms to be
   undercut by the front in this area, the strongest updrafts may still
   be accompanied by hail and isolated strong/severe wind gusts.  

   ...ArkLaTex to Lower Mississippi Valley...
   Near the warm front or within the warm sector, there is some
   potential that a supercell or two could develop out of initially
   elevated convection across the ArkLaTex region late this
   afternoon/early evening. However, lingering cloud cover seems likely
   to temper insolation/low-level lapse rates to a degree, which would
   make discrete surface-based development less likely prior to the
   upstream near-cold frontal convective regime that will be regionally
   inbound from northwest to southeast this evening. Thus, while an
   isolated supercell/severe risk may exist late this afternoon, severe
   potential will become more probable toward/after 00z, although a
   weakening trend is expected overnight as storms move into a less
   unstable environment. Some threat for locally damaging winds and/or
   a brief tornado may extend as far east-southeast as the lower
   Mississippi Valley through 12Z Friday morning.

   ..Guyer/Broyles.. 03/16/2023

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