Latest WV/RAP PV analysis shows a shortwave rotating around the base of a persistent deep closed low to the west of the area early this afternoon. Subtle forcing from this feature should aid in convective development throughout the afternoon. 12z observed sounding at Midland shows a more moist boundary layer than the observation 12 hours prior with nearly saturated profile up to about 5KFT AGL where the base of a weak residual EML is present transported by modest westerly flow at this level extending up through the mid/upper atmosphere. Surface flow was not particularly strong per latest surface obs but plentiful surface moisture was already present with upper 50 to lower 60 degree dew points across much of southwest Texas east of the Davis Mountains. Some convection has initiated already mainly along and near terrain north. More widespread convection and a higher chance of severe will come later as diabatic heating contributes to greater instability and aforementioned shortwave nears. ~40 knots of effecive bulk shear should support organized cells including potential for supercells in an increasingly/moderately unstable environment. Convective initiation is expected mostly around difficult to define surface boundaries and terrain features.

-dryadiabat

Mesoscale Discussion as of 1830z (J-Money):

On the large-scale, water vapor imagery shows an upstream short-wave over northern NM, rotating around the Rockies Front Range upper low.  As this feature continues to swing eastward into West TX this afternoon, convective coverage should grow.  This may especially be the case in the TX Big Bend area (MAF CWA), where the atmosphere is more unstable at this time (ML Capes of 750-1500 and 700-500 mb LR’s of 7+ C/km).  Although deep-layered shear is marginal as of 18z (0-3 km values of 15-20 kt), it should improve later this afternoon, as stronger mid-level winds rotate from Mexico and NM into West Texas.  This presumed unstable, deep-layer shear environment should support large hail with any supercell structures, and perhaps isolated downburst type winds.  1-minute visible imagery has been depicting increasingly rapid convective blowoff to the east with initial convective towers, perhaps attesting to the developing mid-level shear.  Once again today, the tornado threat looks low, with weaker 0-1 km shear and elevated LCL heights.

Regular CI products have been hinting at near-future storm formation in MAF’s CWA, just west of where a persistent low cloud mass is clearing out.  So far, Severe CI and Prob Severe values have been low.  We’ll monitor closely.

1930z Mesoscale Update

Diffuse surface front now stalled across the Permian Basin of west Texas.  South of this boundary, the 1-km GOES-14 data showing ample clearing of low clouds as daytime heating continues to heat the boundary layer this afternoon. As a result of surface dewpoints residing in the upper 50 to low 60s, moderate levels of instability have developed with latest SPC mesoanalysis showing 1500-2000 joules of MLCAPE. Deep-layered shear on the order 40 kts should allow for supercell structures as forcing for ascent increases ahead of pronounced shortwave trough appraching from south-central New Mexico. With -20C levels around 19.4 kft, supercells will be capable of large hail and strong damaging winds thanks for steep low and midlevel lapse rates.