SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0630 AM CST Sun Jan 10 2021 Valid 101300Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Sporadic non-severe thunderstorms are possible over south Texas and southern Louisiana. ...Synopsis... In mid/upper levels, the large-scale pattern will be characterized by a broad cyclone over the Gulf of Alaska, mean ridging from CA across the northern Rockies and northwestern Canada, and a complex, split-flow regime of mean troughing over the central CONUS. The principal southern-stream perturbation, around which the flow splits, is evident in moisture-channel imagery over eastern NM and far west TX, with a nearly closed cyclone around a 500-mb low located over southeastern NM. The low should close fully through the remainder of this morning and move eastward across west TX, reaching the area between CDS-ABI by 00Z. By 12Z, the low should be near TXK, along a deamplifying shortwave trough, then becoming an open wave again and weakening across the Mid-South on day 2. At the surface, a distinct low should develop off Padre Island by around 18Z, from a trough analyzed at 11Z near a BRO-CRP-SAT axis. The low should move east-northeastward from there across the northwestern Gulf, and remaining south of the mainland through the rest of the period. By 12Z, the low should be located south of southeastern LA, with warm front arching to just south of the moth of the Mississippi River, then southeastward over the east-central Gulf. A cold front will trail south-southwestward from the low across the northwestern Gulf. ...South TX... Isolated to widely scattered thunderstorms are possible today across much of south TX, within a broad plume of elevated, low-level warm advection and moisture transport wrapping toward the mid/upper low. This activity will be supported by elevated MUCAPE in the 200-500 J/kg range, rooted around 750-850 mb in southern areas and 650-750 mb from the Edwards Plateau across south-central TX. A main convective swath -- perhaps a southward extension of the zone of elevated frontogenetic lift now passing the AQO/SAT/COT corridor -- should evolve through the day just inland from the lower TX Coast and shift eastward. This activity should remain elevated and non- severe over land, behind the developing surface cyclone. The convection should increase in coverage and intensify after reaching the Gulf surface low and encountering a higher-theta-e, more surface-rooted inflow layer of the warm sector. Forecast soundings suggest that deep shear and CAPE may become favorable for a severe threat affecting offshore interests well south of the upper TX and LA Coasts, but should not extend inland/north of the warm front, due to lack of boundary-layer buoyancy. ..Edwards/Mosier.. 01/10/2021
There’s more click here.