SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0647 AM CST Wed Feb 10 2021 Valid 101300Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis... An elongated, binary and very cold mid/upper cyclone will pivot over central Canada through this period. A Fujiwhara-style interaction on day 1 is progged to lead to consolidation of the vortex over MB late day 2. To its south, a broad belt of intense mid/upper westerlies -- with gently cyclonic curvature -- will cover much of the central and northern CONUS. A southern-stream split-flow pattern will exist over the Southwest and northern/western MX, related to a trough now extending near an axis from LAS-SAN and south-southwestward across the Pacific west of Baja. By 12Z tomorrow, the trough should maintain similarly positive tilt with some amplification, from near SAF-DMN and across northwestern mainland MX and southern Baja. At the surface, 11Z analysis depicted a quasistationary front across central FL and the extreme northern Gulf, to deep south TX. Very slow northward drift of this boundary as a warm front should occur in most sections, with western portions merging into the more- intense Arctic baroclinic zone slowly sagging equatorward across south TX. The latter front should reach the lower Rio Grande Valley late in the period. ...South-central/southeastern CONUS... Multiple rounds of isolated to scattered convection, with sporadic thunderstorms, are possible through the period across the lengthy outlook area, mainly north of the Gulf frontal zone. Any surface- based storms over coastal areas generally should occur amidst weak CINH, but also, weak low-level shear and a lack of substantial mid/upper support. Very late in the period (likely around 09-12Z), convection may develop over parts of the TX Rio Grande Valley and vicinity, upriver from LRD and northward toward the southern Hill Country. A combination of frontal lift above the surface and increasing inflow- layer moisture/theta-e will erode EML-related MUCINH, ahead of the northwest Mexico perturbation. MLCAPE locally exceeding 1000 J/kg may develop, and with forecast soundings exhibiting 40-50-kt effective-shear vectors, isolated hail approaching severe limits cannot be ruled out. Accordingly, the thunder area has been expanded westward across south TX. The other change of note is minor eastward extension in more of the Tennessee Valley region, also to account for late-overnight thunder potential shortly before 12Z. There, the fringe of favorable, elevated low-level warm advection and moistening should support development of 300-500 J/kg MLCAPE extending into suitable icing layers for isolated lightning. ..Edwards.. 02/10/2021
There’s more click here.