1930z Update

As of about 1930z (J-Money):

Convection seems to be primarily terrain forced so far in MAF's CWA.  1-minute visible imagery is showing a more stable wave-like appearance to the cumulus field outside of the Davis Ridge area.  The more agitated cumulus elements seem to be isolated to ridge top regions.  Synoptic-scale forcing has been insufficient to generate much thunderstorm development otherwise so far, as the main short-wave is still off to the west over NM.

Meanwhile, up in LBB's area, 1-minute visible pictures and radar imagery show elevated storms tracking to the east, with some clearing coming in from the west behind this activity.  If enough air mass recovery and moisture advection can occur in the next 1-3 hours this area, the incoming short-wave could support more robust development later.  Time will tell.

CI Lighting up across northern Brewster County, TX

Agitated CU becoming more apparent over the higher terrain (Davis Mtns) of west Texas.  Convective initiation product beginning to show increased probabilities of development within the next 2 hours.   

Early Afternoon Mesoanalysis Update

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

Lap / CI first look

Initially the GOES-r lap 4-panel showing precip water above .80" and cape across  the area from 400 to just over 600j/j/kg.  One minute satellite data and water vapor image supports a westerly flow aloft. With elevated shear in place. it will be interesting to see how the CI probability picks up convection. At this point both CI prob and CI prob severe are showing low probability.

thunder

Mesoscale Discussion as of 1830z

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. 

Midland Texas

Today both groups are setting up in the Midland, Texas WFO.  Compared to yesterday the environment has more shear, generally 30-40 knots of effective bulk shear compared to 10-20 knots in southern Texas yesterday.  The instability is less however.

-Sieglaff

Daily Summary: Week 1, Day 1 (April 18, 2016)

Today's activities took place in the Corpus Christi and Brownsville CWA's.

LAP
- A participant created a new colortable that was preferred over the default

CI
- An indicator of why probabilities dropped out would be nice
- We had good indicators from regular CI, but severe CI was very low. Despite lack of reports, some storms appeared to be severe.

ProbSevere
- I would show this on TV
- It did not provide much lead time to the intesification of the storm
- Storms that ended up being the strongest had strong glaciation rates

1-min imagery
-  Boundary sagging south across texas yesterday, storm developed on boundary, then started to lag behind boundary on cool side, when it started to rotate. 1 min imagery was helpful in showing that storm would stay on the cold side, didn’t seem like it had a good shot at tor potential. The 1min imagery was been helpful in showing that.

Lightning Jump
- Biggest complaint was that the display covered up other data; recommended to make it transparent.

NUCAPS
- Corpus had an 18Z sounding, so we did a comparison. For the most part it matched up, just lacked the vertical detail, could not tell if CAP was still in place. NUCAPS confirmed drier air was moving in.

Glaciation Rates

As a followup to the previous post on the Hidalgo County storm, there may be some value in glaciation rates. It's a small sample size but two of the storms that clearly were severe based on radar and confirmed by prob severe also displayed "strong". It may be worth exploring further the value of glaciation rates for these low shear / high CAPE environments where prob severe seems to offer little or no lead time.

-dryadiabat

LAP Layer PW Suggestion

Layered precipitable water suggestion:  It seems that the "upper-level" panel is far too broad/deep (700-300 mb).  If we can only show 3 layers, how about something like surface-850 mb, 850-700 mb, and 700-500 mb.  The more narrow, specific ranges between 850 and 500 mb would likely afford a better opportunity to see EML/dry regions, whereas 700-300 mb could wash these features out.

                                    Upper-right panel is too broad/deep.