SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0741 AM CDT Wed Oct 27 2021 Valid 271300Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF LOUISIANA AND FAR SOUTHEAST TEXAS... ...SUMMARY... Isolated to scattered severe thunderstorms capable of producing damaging winds and tornadoes are expected today and tonight from far east/southeast Texas into Louisiana and other parts of the Gulf Coast region. ...Southeast Texas/Louisiana and Middle Gulf Coast... The region will be influenced today by an increasingly moist air mass preceding an eastward-moving full-latitude trough that is centered over the Plains early this morning. Linearly continuous outflow from last night's storms extends from far eastern Oklahoma southward into east-central/southern Texas where a stronger convective line exists early this morning. Other convective-line preceding showers/thunderstorms have increased near the upper Texas coast and coastal southwest Louisiana, some of which have exhibited supercellular characteristics. For additional short-term details, see Mesoscale Discussion 1911. The convective line will continue generally eastward across far east Texas into Louisiana today while re-intensifying into late morning/afternoon as the boundary layer further moistens and destabilizes. Other line-leading more-discrete development including supercells are also anticipated within the very moist/minimally inhibited boundary layer by afternoon (even with relatively warm mid-level temperatures). Damaging winds are viable with the strongest storms, but a tornado risk will exist as well, both with semi-discrete supercells and QLCS-related mesovortices. Furthermore, a couple of strong tornadoes could occur, particularly as southwesterly winds within the lowest 1-3 km AGL are expected to dramatically strengthen this afternoon, with a corresponding increase in SRH within the warm sector northward to near the warm front/triple point vicinity located across Louisiana. The tornado and damaging wind threat will shift eastward into southern portions of Mississippi/Alabama this evening and the Florida Panhandle vicinity tonight and early Thursday morning. Sufficient boundary layer instability could support some surface-based storms tonight, particularly in near-coastal portions of the region. ...ArkLaTex vicinity... In the wake of lingering early day convection, a low-topped convective line may develop this afternoon across parts of eastern Oklahoma/northeast Texas into western/southern Arkansas near the surface low and narrow/minimally unstable warm sector. Even though low-level moisture will be more limited across this area, cold mid-level temperatures associated with the upper trough may still support weak destabilization. Strong low/deep-layer shear suggests some threat for isolated damaging winds and perhaps even a brief tornado. Any such risk will lessen this evening across Arkansas/northern Louisiana owing to waning instability with the loss of daytime heating. ..Guyer/Kerr.. 10/27/2021 Read more LIVE: spc.noaa.gov
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