ZCZC SPCSWOMCD ALL ACUS11 KWNS 170632 SPC MCD 170632 MSZ000-ARZ000-LAZ000-TXZ000-OKZ000-170830- Mesoscale Discussion 0190 NWS Storm Prediction Center Norman OK 0132 AM CDT Wed Mar 17 2021 Areas affected...Portions of northeast TX...northern LA...southern/central AR...and southeastern OK Concerning...Severe potential...Watch possible Valid 170632Z - 170830Z Probability of Watch Issuance...40 percent SUMMARY...If surface-based storms can develop, then a threat for large hail, damaging wind gusts, and a couple tornadoes would exist. Watch issuance is possible. DISCUSSION...An elevated storm in southern AR recently produced near-severe caliber hail before weakening. Additional convection has recently developed along the OK/AR border and northeast TX in a southerly low-level warm advection regime. It remains unclear whether surface-based storms will develop over the next couple of hours across the ArkLaTex vicinity, as stronger forcing associated with an ejecting upper low remains to the west (over the southern Plains). Regardless, surface dewpoints have generally increased into the mid to upper 60s across this region, and RAP forecast soundings suggest that any storms that do develop could become surface based. Deep-layer shear remains very favorable for supercells (45-50+ kt), and recent VWPs from KSHV show nearly 40 kt of 0-1 km shear and 250+ m2/s2 0-1 km SRH. Steep mid-level lapse rates noted on the 00Z SHV sounding combined with the favorable storm mode would support large hail. Given the enhanced low-level flow/shear, a couple tornadoes and isolated damaging winds may also occur. At this point, watch issuance remains uncertain, mainly because it is not clear how many storms will develop over the next couple of hours in the open warm sector. ..Gleason/Thompson.. 03/17/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...JAN...LZK...SHV...TSA... LAT...LON 31839468 32439502 34059522 34769503 35179467 35379432 35269327 34779195 34169128 33599119 32519185 31889295 31719400 31839468 NNNN